update sources to v12.2.3

[ceph.git] / ceph / src / civetweb / src / civetweb.c

/* Copyright (c) 2013-2016 the Civetweb developers
 * Copyright (c) 2004-2013 Sergey Lyubka
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */


#if defined(_WIN32)
#if !defined(_CRT_SECURE_NO_WARNINGS)
#define _CRT_SECURE_NO_WARNINGS /* Disable deprecation warning in VS2005 */
#endif
#ifndef _WIN32_WINNT /* defined for tdm-gcc so we can use getnameinfo */
#define _WIN32_WINNT 0x0501
#endif
#else
#if defined(__GNUC__) && !defined(_GNU_SOURCE)
#define _GNU_SOURCE /* for setgroups() */
#endif
#if defined(__linux__) && !defined(_XOPEN_SOURCE)
#define _XOPEN_SOURCE 600 /* For flockfile() on Linux */
#endif
#ifndef _LARGEFILE_SOURCE
#define _LARGEFILE_SOURCE /* For fseeko(), ftello() */
#endif
#ifndef _FILE_OFFSET_BITS
#define _FILE_OFFSET_BITS 64 /* Use 64-bit file offsets by default */
#endif
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS /* <inttypes.h> wants this for C++ */
#endif
#ifndef __STDC_LIMIT_MACROS
#define __STDC_LIMIT_MACROS /* C++ wants that for INT64_MAX */
#endif
#ifdef __sun
#define __EXTENSIONS__  /* to expose flockfile and friends in stdio.h */
#define __inline inline /* not recognized on older compiler versions */
#endif
#endif

#if defined(USE_LUA) && defined(USE_WEBSOCKET)
#define USE_TIMERS
#endif

#if defined(_MSC_VER)
/* 'type cast' : conversion from 'int' to 'HANDLE' of greater size */
#pragma warning(disable : 4306)
/* conditional expression is constant: introduced by FD_SET(..) */
#pragma warning(disable : 4127)
/* non-constant aggregate initializer: issued due to missing C99 support */
#pragma warning(disable : 4204)
/* padding added after data member */
#pragma warning(disable : 4820)
/* not defined as a preprocessor macro, replacing with '0' for '#if/#elif' */
#pragma warning(disable : 4668)
/* no function prototype given: converting '()' to '(void)' */
#pragma warning(disable : 4255)
/* function has been selected for automatic inline expansion */
#pragma warning(disable : 4711)
#endif


/* This code uses static_assert to check some conditions.
 * Unfortunately some compilers still do not support it, so we have a
 * replacement function here. */
#if defined(_MSC_VER) && (_MSC_VER >= 1600)
#define mg_static_assert static_assert
#elif defined(__cplusplus) && (__cplusplus >= 201103L)
#define mg_static_assert static_assert
#elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L)
#define mg_static_assert _Static_assert
#else
char static_assert_replacement[1];
#define mg_static_assert(cond, txt)                                            \
        extern char static_assert_replacement[(cond) ? 1 : -1]
#endif

mg_static_assert(sizeof(int) == 4 || sizeof(int) == 8,
                 "int data type size check");
mg_static_assert(sizeof(void *) == 4 || sizeof(void *) == 8,
                 "pointer data type size check");
mg_static_assert(sizeof(void *) >= sizeof(int), "data type size check");
/* mg_static_assert(sizeof(size_t) == 4 || sizeof(size_t) == 8, "size_t data
 * type size check"); */

/* DTL -- including winsock2.h works better if lean and mean */
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif

#if defined(__SYMBIAN32__)
#define NO_SSL /* SSL is not supported */
#define NO_CGI /* CGI is not supported */
#define PATH_MAX FILENAME_MAX
#endif /* __SYMBIAN32__ */


/* Include the header file here, so the CivetWeb interface is defined for the
 * entire implementation, including the following forward definitions. */
#include "civetweb.h"


#ifndef IGNORE_UNUSED_RESULT
#define IGNORE_UNUSED_RESULT(a) ((void)((a) && 1))
#endif

#ifndef _WIN32_WCE /* Some ANSI #includes are not available on Windows CE */
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#endif /* !_WIN32_WCE */

#ifdef __MACH__

#define CLOCK_MONOTONIC (1)
#define CLOCK_REALTIME (2)

#include <sys/time.h>
#include <mach/clock.h>
#include <mach/mach.h>
#include <mach/mach_time.h>
#include <assert.h>


/* clock_gettime is not implemented on OSX */
int clock_gettime(int clk_id, struct timespec *t);

int
clock_gettime(int clk_id, struct timespec *t)
{
        memset(t, 0, sizeof(*t));
        if (clk_id == CLOCK_REALTIME) {
                struct timeval now;
                int rv = gettimeofday(&now, NULL);
                if (rv) {
                        return rv;
                }
                t->tv_sec = now.tv_sec;
                t->tv_nsec = now.tv_usec * 1000;
                return 0;

        } else if (clk_id == CLOCK_MONOTONIC) {
                static uint64_t clock_start_time = 0;
                static mach_timebase_info_data_t timebase_ifo = {0, 0};

                uint64_t now = mach_absolute_time();

                if (clock_start_time == 0) {
                        kern_return_t mach_status = mach_timebase_info(&timebase_ifo);
#if defined(DEBUG)
                        assert(mach_status == KERN_SUCCESS);
#else
                        /* appease "unused variable" warning for release builds */
                        (void)mach_status;
#endif
                        clock_start_time = now;
                }

                now = (uint64_t)((double)(now - clock_start_time)
                                 * (double)timebase_ifo.numer
                                 / (double)timebase_ifo.denom);

                t->tv_sec = now / 1000000000;
                t->tv_nsec = now % 1000000000;
                return 0;
        }
        return -1; /* EINVAL - Clock ID is unknown */
}
#endif


#include <time.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>


#ifndef MAX_WORKER_THREADS
#define MAX_WORKER_THREADS (1024 * 64)
#endif
#ifndef SOCKET_TIMEOUT_QUANTUM
#define SOCKET_TIMEOUT_QUANTUM (10000)
#endif

mg_static_assert(MAX_WORKER_THREADS >= 1,
                 "worker threads must be a positive number");

#if defined(_WIN32)                                                            \
    && !defined(__SYMBIAN32__) /* WINDOWS / UNIX include block */
#include <windows.h>
#include <winsock2.h> /* DTL add for SO_EXCLUSIVE */
#include <ws2tcpip.h>

typedef const char *SOCK_OPT_TYPE;

#if !defined(PATH_MAX)
#define PATH_MAX (MAX_PATH)
#endif

#if !defined(PATH_MAX)
#define PATH_MAX (4096)
#endif

mg_static_assert(PATH_MAX >= 1, "path length must be a positive number");

#ifndef _IN_PORT_T
#ifndef in_port_t
#define in_port_t u_short
#endif
#endif

#ifndef _WIN32_WCE
#include <process.h>
#include <direct.h>
#include <io.h>
#else          /* _WIN32_WCE */
#define NO_CGI /* WinCE has no pipes */

typedef long off_t;

#define errno ((int)(GetLastError()))
#define strerror(x) (_ultoa(x, (char *)_alloca(sizeof(x) * 3), 10))
#endif /* _WIN32_WCE */

#define MAKEUQUAD(lo, hi)                                                      \
        ((uint64_t)(((uint32_t)(lo)) | ((uint64_t)((uint32_t)(hi))) << 32))
#define RATE_DIFF (10000000) /* 100 nsecs */
#define EPOCH_DIFF (MAKEUQUAD(0xd53e8000, 0x019db1de))
#define SYS2UNIX_TIME(lo, hi)                                                  \
        ((time_t)((MAKEUQUAD((lo), (hi)) - EPOCH_DIFF) / RATE_DIFF))

/* Visual Studio 6 does not know __func__ or __FUNCTION__
 * The rest of MS compilers use __FUNCTION__, not C99 __func__
 * Also use _strtoui64 on modern M$ compilers */
#if defined(_MSC_VER)
#if (_MSC_VER < 1300)
#define STRX(x) #x
#define STR(x) STRX(x)
#define __func__ __FILE__ ":" STR(__LINE__)
#define strtoull(x, y, z) ((unsigned __int64)_atoi64(x))
#define strtoll(x, y, z) (_atoi64(x))
#else
#define __func__ __FUNCTION__
#define strtoull(x, y, z) (_strtoui64(x, y, z))
#define strtoll(x, y, z) (_strtoi64(x, y, z))
#endif
#endif /* _MSC_VER */

#define ERRNO ((int)(GetLastError()))
#define NO_SOCKLEN_T

#if defined(_WIN64) || defined(__MINGW64__)
#define SSL_LIB "ssleay64.dll"
#define CRYPTO_LIB "libeay64.dll"
#else
#define SSL_LIB "ssleay32.dll"
#define CRYPTO_LIB "libeay32.dll"
#endif

#define O_NONBLOCK (0)
#ifndef W_OK
#define W_OK (2) /* http://msdn.microsoft.com/en-us/library/1w06ktdy.aspx */
#endif
#if !defined(EWOULDBLOCK)
#define EWOULDBLOCK WSAEWOULDBLOCK
#endif /* !EWOULDBLOCK */
#define _POSIX_
#define INT64_FMT "I64d"
#define UINT64_FMT "I64u"

#define WINCDECL __cdecl
#define SHUT_RD (0)
#define SHUT_WR (1)
#define SHUT_BOTH (2)
#define vsnprintf_impl _vsnprintf
#define access _access
#define mg_sleep(x) (Sleep(x))

#define pipe(x) _pipe(x, MG_BUF_LEN, _O_BINARY)
#ifndef popen
#define popen(x, y) (_popen(x, y))
#endif
#ifndef pclose
#define pclose(x) (_pclose(x))
#endif
#define close(x) (_close(x))
#define dlsym(x, y) (GetProcAddress((HINSTANCE)(x), (y)))
#define RTLD_LAZY (0)
#define fseeko(x, y, z) (_lseeki64(_fileno(x), (y), (z)) == -1 ? -1 : 0)
#define fdopen(x, y) (_fdopen((x), (y)))
#define write(x, y, z) (_write((x), (y), (unsigned)z))
#define read(x, y, z) (_read((x), (y), (unsigned)z))
#define flockfile(x) (EnterCriticalSection(&global_log_file_lock))
#define funlockfile(x) (LeaveCriticalSection(&global_log_file_lock))
#define sleep(x) (Sleep((x)*1000))
#define rmdir(x) (_rmdir(x))
#define timegm(x) (_mkgmtime(x))

#if !defined(fileno)
#define fileno(x) (_fileno(x))
#endif /* !fileno MINGW #defines fileno */

typedef HANDLE pthread_mutex_t;
typedef DWORD pthread_key_t;
typedef HANDLE pthread_t;
typedef struct {
        CRITICAL_SECTION threadIdSec;
        int waitingthreadcount;       /* The number of threads queued. */
        pthread_t *waitingthreadhdls; /* The thread handles. */
} pthread_cond_t;

#ifndef __clockid_t_defined
typedef DWORD clockid_t;
#endif
#ifndef CLOCK_MONOTONIC
#define CLOCK_MONOTONIC (1)
#endif
#ifndef CLOCK_REALTIME
#define CLOCK_REALTIME (2)
#endif

#if defined(_MSC_VER) && (_MSC_VER >= 1900)
#define _TIMESPEC_DEFINED
#endif
#ifndef _TIMESPEC_DEFINED
struct timespec {
        time_t tv_sec; /* seconds */
        long tv_nsec;  /* nanoseconds */
};
#endif

#define pid_t HANDLE /* MINGW typedefs pid_t to int. Using #define here. */

static int pthread_mutex_lock(pthread_mutex_t *);
static int pthread_mutex_unlock(pthread_mutex_t *);
static void path_to_unicode(const struct mg_connection *conn,
                            const char *path,
                            wchar_t *wbuf,
                            size_t wbuf_len);
struct file;
static const char *
mg_fgets(char *buf, size_t size, struct file *filep, char **p);


#if defined(HAVE_STDINT)
#include <stdint.h>
#else
typedef unsigned char uint8_t;
typedef unsigned short uint16_t;
typedef unsigned int uint32_t;
typedef unsigned __int64 uint64_t;
typedef __int64 int64_t;
#define INT64_MAX (9223372036854775807)
#endif /* HAVE_STDINT */

/* POSIX dirent interface */
struct dirent {
        char d_name[PATH_MAX];
};

typedef struct DIR {
        HANDLE handle;
        WIN32_FIND_DATAW info;
        struct dirent result;
} DIR;

#if defined(_WIN32) && !defined(POLLIN)
#ifndef HAVE_POLL
struct pollfd {
        SOCKET fd;
        short events;
        short revents;
};
#define POLLIN (0x0300)
#endif
#endif

/* Mark required libraries */
#if defined(_MSC_VER)
#pragma comment(lib, "Ws2_32.lib")
#endif

#else /* defined(_WIN32) && !defined(__SYMBIAN32__) - WINDOWS / UNIX include   \
         block */

#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <sys/utsname.h>
#include <stdint.h>
#include <inttypes.h>
#include <netdb.h>
#include <netinet/tcp.h>
typedef const void *SOCK_OPT_TYPE;

#if defined(ANDROID)
typedef unsigned short int in_port_t;
#endif

#include <pwd.h>
#include <unistd.h>
#include <grp.h>
#include <dirent.h>
#define vsnprintf_impl vsnprintf

#if !defined(NO_SSL_DL) && !defined(NO_SSL)
#include <dlfcn.h>
#endif
#include <pthread.h>
#if defined(__MACH__)
#define SSL_LIB "libssl.dylib"
#define CRYPTO_LIB "libcrypto.dylib"
#else
#if !defined(SSL_LIB)
#define SSL_LIB "libssl.so"
#endif
#if !defined(CRYPTO_LIB)
#define CRYPTO_LIB "libcrypto.so"
#endif
#endif
#ifndef O_BINARY
#define O_BINARY (0)
#endif /* O_BINARY */
#define closesocket(a) (close(a))
#define mg_mkdir(conn, path, mode) (mkdir(path, mode))
#define mg_remove(conn, x) (remove(x))
#define mg_sleep(x) (usleep((x)*1000))
#define mg_opendir(conn, x) (opendir(x))
#define mg_closedir(x) (closedir(x))
#define mg_readdir(x) (readdir(x))
#define ERRNO (errno)
#define INVALID_SOCKET (-1)
#define INT64_FMT PRId64
#define UINT64_FMT PRIu64
typedef int SOCKET;
#define WINCDECL

#if defined(__hpux)
/* HPUX 11 does not have monotonic, fall back to realtime */
#ifndef CLOCK_MONOTONIC
#define CLOCK_MONOTONIC CLOCK_REALTIME
#endif

/* HPUX defines socklen_t incorrectly as size_t which is 64bit on
 * Itanium.  Without defining _XOPEN_SOURCE or _XOPEN_SOURCE_EXTENDED
 * the prototypes use int* rather than socklen_t* which matches the
 * actual library expectation.  When called with the wrong size arg
 * accept() returns a zero client inet addr and check_acl() always
 * fails.  Since socklen_t is widely used below, just force replace
 * their typedef with int. - DTL
 */
#define socklen_t int
#endif /* hpux */

#endif /* defined(_WIN32) && !defined(__SYMBIAN32__) - WINDOWS / UNIX include  \
          block */

/* va_copy should always be a macro, C99 and C++11 - DTL */
#ifndef va_copy
#define va_copy(x, y) ((x) = (y))
#endif

#ifdef _WIN32
/* Create substitutes for POSIX functions in Win32. */

#if defined(__MINGW32__)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif


static CRITICAL_SECTION global_log_file_lock;
static DWORD
pthread_self(void)
{
        return GetCurrentThreadId();
}


static int
pthread_key_create(
    pthread_key_t *key,
    void (*_ignored)(void *) /* destructor not supported for Windows */
    )
{
        (void)_ignored;

        if ((key != 0)) {
                *key = TlsAlloc();
                return (*key != TLS_OUT_OF_INDEXES) ? 0 : -1;
        }
        return -2;
}


static int
pthread_key_delete(pthread_key_t key)
{
        return TlsFree(key) ? 0 : 1;
}


static int
pthread_setspecific(pthread_key_t key, void *value)
{
        return TlsSetValue(key, value) ? 0 : 1;
}


static void *
pthread_getspecific(pthread_key_t key)
{
        return TlsGetValue(key);
}

#if defined(__MINGW32__)
/* Enable unused function warning again */
#pragma GCC diagnostic pop
#endif

static struct pthread_mutex_undefined_struct *pthread_mutex_attr = NULL;
#else
static pthread_mutexattr_t pthread_mutex_attr;
#endif /* _WIN32 */


#define PASSWORDS_FILE_NAME ".htpasswd"
#define CGI_ENVIRONMENT_SIZE (4096)
#define MAX_CGI_ENVIR_VARS (256)
#define MG_BUF_LEN (8192)

#ifndef MAX_REQUEST_SIZE
#define MAX_REQUEST_SIZE (16384)
#endif

mg_static_assert(MAX_REQUEST_SIZE >= 256,
                 "request size length must be a positive number");

#define ARRAY_SIZE(array) (sizeof(array) / sizeof(array[0]))

#if !defined(DEBUG_TRACE)
#if defined(DEBUG)


static void DEBUG_TRACE_FUNC(const char *func,
                             unsigned line,
                             PRINTF_FORMAT_STRING(const char *fmt),
                             ...) PRINTF_ARGS(3, 4);

static void
DEBUG_TRACE_FUNC(const char *func, unsigned line, const char *fmt, ...)
{
        va_list args;
        flockfile(stdout);
        printf("*** %lu.%p.%s.%u: ",
               (unsigned long)time(NULL),
               (void *)pthread_self(),
               func,
               line);
        va_start(args, fmt);
        vprintf(fmt, args);
        va_end(args);
        putchar('\n');
        fflush(stdout);
        funlockfile(stdout);
}

#define DEBUG_TRACE(fmt, ...)                                                  \
        DEBUG_TRACE_FUNC(__func__, __LINE__, fmt, __VA_ARGS__)

#else
#define DEBUG_TRACE(fmt, ...)                                                  \
        do {                                                                       \
        } while (0)
#endif /* DEBUG */
#endif /* DEBUG_TRACE */

#if defined(MEMORY_DEBUGGING)
unsigned long mg_memory_debug_blockCount = 0;
unsigned long mg_memory_debug_totalMemUsed = 0;


static void *
mg_malloc_ex(size_t size, const char *file, unsigned line)
{
        void *data = malloc(size + sizeof(size_t));
        void *memory = 0;
        char mallocStr[256];

        if (data) {
                *(size_t *)data = size;
                mg_memory_debug_totalMemUsed += size;
                mg_memory_debug_blockCount++;
                memory = (void *)(((char *)data) + sizeof(size_t));
        }

        sprintf(mallocStr,
                "MEM: %p %5lu alloc   %7lu %4lu --- %s:%u\n",
                memory,
                (unsigned long)size,
                mg_memory_debug_totalMemUsed,
                mg_memory_debug_blockCount,
                file,
                line);
#if defined(_WIN32)
        OutputDebugStringA(mallocStr);
#else
        DEBUG_TRACE("%s", mallocStr);
#endif

        return memory;
}


static void *
mg_calloc_ex(size_t count, size_t size, const char *file, unsigned line)
{
        void *data = mg_malloc_ex(size * count, file, line);
        if (data) {
                memset(data, 0, size);
        }
        return data;
}


static void
mg_free_ex(void *memory, const char *file, unsigned line)
{
        char mallocStr[256];
        void *data = (void *)(((char *)memory) - sizeof(size_t));
        size_t size;

        if (memory) {
                size = *(size_t *)data;
                mg_memory_debug_totalMemUsed -= size;
                mg_memory_debug_blockCount--;
                sprintf(mallocStr,
                        "MEM: %p %5lu free    %7lu %4lu --- %s:%u\n",
                        memory,
                        (unsigned long)size,
                        mg_memory_debug_totalMemUsed,
                        mg_memory_debug_blockCount,
                        file,
                        line);
#if defined(_WIN32)
                OutputDebugStringA(mallocStr);
#else
                DEBUG_TRACE("%s", mallocStr);
#endif

                free(data);
        }
}


static void *
mg_realloc_ex(void *memory, size_t newsize, const char *file, unsigned line)
{
        char mallocStr[256];
        void *data;
        void *_realloc;
        size_t oldsize;

        if (newsize) {
                if (memory) {
                        data = (void *)(((char *)memory) - sizeof(size_t));
                        oldsize = *(size_t *)data;
                        _realloc = realloc(data, newsize + sizeof(size_t));
                        if (_realloc) {
                                data = _realloc;
                                mg_memory_debug_totalMemUsed -= oldsize;
                                sprintf(mallocStr,
                                        "MEM: %p %5lu r-free  %7lu %4lu --- %s:%u\n",
                                        memory,
                                        (unsigned long)oldsize,
                                        mg_memory_debug_totalMemUsed,
                                        mg_memory_debug_blockCount,
                                        file,
                                        line);
#if defined(_WIN32)
                                OutputDebugStringA(mallocStr);
#else
                                DEBUG_TRACE("%s", mallocStr);
#endif
                                mg_memory_debug_totalMemUsed += newsize;
                                sprintf(mallocStr,
                                        "MEM: %p %5lu r-alloc %7lu %4lu --- %s:%u\n",
                                        memory,
                                        (unsigned long)newsize,
                                        mg_memory_debug_totalMemUsed,
                                        mg_memory_debug_blockCount,
                                        file,
                                        line);
#if defined(_WIN32)
                                OutputDebugStringA(mallocStr);
#else
                                DEBUG_TRACE("%s", mallocStr);
#endif
                                *(size_t *)data = newsize;
                                data = (void *)(((char *)data) + sizeof(size_t));
                        } else {
#if defined(_WIN32)
                                OutputDebugStringA("MEM: realloc failed\n");
#else
                                DEBUG_TRACE("%s", "MEM: realloc failed\n");
#endif
                                return _realloc;
                        }
                } else {
                        data = mg_malloc_ex(newsize, file, line);
                }
        } else {
                data = 0;
                mg_free_ex(memory, file, line);
        }

        return data;
}

#define mg_malloc(a) mg_malloc_ex(a, __FILE__, __LINE__)
#define mg_calloc(a, b) mg_calloc_ex(a, b, __FILE__, __LINE__)
#define mg_realloc(a, b) mg_realloc_ex(a, b, __FILE__, __LINE__)
#define mg_free(a) mg_free_ex(a, __FILE__, __LINE__)

#else

static __inline void *
mg_malloc(size_t a)
{
        return malloc(a);
}

static __inline void *
mg_calloc(size_t a, size_t b)
{
        return calloc(a, b);
}

static __inline void *
mg_realloc(void *a, size_t b)
{
        return realloc(a, b);
}

static __inline void
mg_free(void *a)
{
        free(a);
}

#endif


static void mg_vsnprintf(const struct mg_connection *conn,
                         int *truncated,
                         char *buf,
                         size_t buflen,
                         const char *fmt,
                         va_list ap);

static void mg_snprintf(const struct mg_connection *conn,
                        int *truncated,
                        char *buf,
                        size_t buflen,
                        PRINTF_FORMAT_STRING(const char *fmt),
                        ...) PRINTF_ARGS(5, 6);

/* This following lines are just meant as a reminder to use the mg-functions
 * for memory management */
#ifdef malloc
#undef malloc
#endif
#ifdef calloc
#undef calloc
#endif
#ifdef realloc
#undef realloc
#endif
#ifdef free
#undef free
#endif
#ifdef snprintf
#undef snprintf
#endif
#ifdef vsnprintf
#undef vsnprintf
#endif
#define malloc DO_NOT_USE_THIS_FUNCTION__USE_mg_malloc
#define calloc DO_NOT_USE_THIS_FUNCTION__USE_mg_calloc
#define realloc DO_NOT_USE_THIS_FUNCTION__USE_mg_realloc
#define free DO_NOT_USE_THIS_FUNCTION__USE_mg_free
#define snprintf DO_NOT_USE_THIS_FUNCTION__USE_mg_snprintf
#ifdef _WIN32 /* vsnprintf must not be used in any system, *                   \
               * but this define only works well for Windows. */
#define vsnprintf DO_NOT_USE_THIS_FUNCTION__USE_mg_vsnprintf
#endif

#define MD5_STATIC static
#include "md5.inl"

/* Darwin prior to 7.0 and Win32 do not have socklen_t */
#ifdef NO_SOCKLEN_T
typedef int socklen_t;
#endif /* NO_SOCKLEN_T */
#define _DARWIN_UNLIMITED_SELECT

#define IP_ADDR_STR_LEN (50) /* IPv6 hex string is 46 chars */

#if !defined(MSG_NOSIGNAL)
#define MSG_NOSIGNAL (0)
#endif

#if !defined(SOMAXCONN)
#define SOMAXCONN (100)
#endif

/* Size of the accepted socket queue */
#if !defined(MGSQLEN)
#define MGSQLEN (20)
#endif

#if defined(NO_SSL_DL)
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/crypto.h>
#include <openssl/x509.h>
#include <openssl/pem.h>
#else
/* SSL loaded dynamically from DLL.
 * I put the prototypes here to be independent from OpenSSL source
 * installation. */

typedef struct ssl_st SSL;
typedef struct ssl_method_st SSL_METHOD;
typedef struct ssl_ctx_st SSL_CTX;
typedef struct x509_store_ctx_st X509_STORE_CTX;

#define SSL_CTRL_OPTIONS (32)
#define SSL_CTRL_CLEAR_OPTIONS (77)
#define SSL_CTRL_SET_ECDH_AUTO (94)

#define SSL_VERIFY_NONE (0)
#define SSL_VERIFY_PEER (1)
#define SSL_VERIFY_FAIL_IF_NO_PEER_CERT (2)
#define SSL_VERIFY_CLIENT_ONCE (4)
#define SSL_OP_ALL ((long)(0x80000BFFUL))
#define SSL_OP_NO_SSLv2 (0x01000000L)
#define SSL_OP_NO_SSLv3 (0x02000000L)
#define SSL_OP_NO_TLSv1 (0x04000000L)
#define SSL_OP_NO_TLSv1_2 (0x08000000L)
#define SSL_OP_NO_TLSv1_1 (0x10000000L)
#define SSL_OP_SINGLE_DH_USE (0x00100000L)

struct ssl_func {
        const char *name;  /* SSL function name */
        void (*ptr)(void); /* Function pointer */
};

#define SSL_free (*(void (*)(SSL *))ssl_sw[0].ptr)
#define SSL_accept (*(int (*)(SSL *))ssl_sw[1].ptr)
#define SSL_connect (*(int (*)(SSL *))ssl_sw[2].ptr)
#define SSL_read (*(int (*)(SSL *, void *, int))ssl_sw[3].ptr)
#define SSL_write (*(int (*)(SSL *, const void *, int))ssl_sw[4].ptr)
#define SSL_get_error (*(int (*)(SSL *, int))ssl_sw[5].ptr)
#define SSL_set_fd (*(int (*)(SSL *, SOCKET))ssl_sw[6].ptr)
#define SSL_new (*(SSL * (*)(SSL_CTX *))ssl_sw[7].ptr)
#define SSL_CTX_new (*(SSL_CTX * (*)(SSL_METHOD *))ssl_sw[8].ptr)
#define SSLv23_server_method (*(SSL_METHOD * (*)(void))ssl_sw[9].ptr)
#define SSL_library_init (*(int (*)(void))ssl_sw[10].ptr)
#define SSL_CTX_use_PrivateKey_file                                            \
        (*(int (*)(SSL_CTX *, const char *, int))ssl_sw[11].ptr)
#define SSL_CTX_use_certificate_file                                           \
        (*(int (*)(SSL_CTX *, const char *, int))ssl_sw[12].ptr)
#define SSL_CTX_set_default_passwd_cb                                          \
        (*(void (*)(SSL_CTX *, mg_callback_t))ssl_sw[13].ptr)
#define SSL_CTX_free (*(void (*)(SSL_CTX *))ssl_sw[14].ptr)
#define SSL_load_error_strings (*(void (*)(void))ssl_sw[15].ptr)
#define SSL_CTX_use_certificate_chain_file                                     \
        (*(int (*)(SSL_CTX *, const char *))ssl_sw[16].ptr)
#define SSLv23_client_method (*(SSL_METHOD * (*)(void))ssl_sw[17].ptr)
#define SSL_pending (*(int (*)(SSL *))ssl_sw[18].ptr)
#define SSL_CTX_set_verify                                                     \
        (*(void (*)(SSL_CTX *,                                                     \
                    int,                                                           \
                    int (*verify_callback)(int, X509_STORE_CTX *)))ssl_sw[19].ptr)
#define SSL_shutdown (*(int (*)(SSL *))ssl_sw[20].ptr)
#define SSL_CTX_load_verify_locations                                          \
        (*(int (*)(SSL_CTX *, const char *, const char *))ssl_sw[21].ptr)
#define SSL_CTX_set_default_verify_paths (*(int (*)(SSL_CTX *))ssl_sw[22].ptr)
#define SSL_CTX_set_verify_depth (*(void (*)(SSL_CTX *, int))ssl_sw[23].ptr)
#define SSL_get_peer_certificate (*(X509 * (*)(SSL *))ssl_sw[24].ptr)
#define SSL_get_version (*(const char *(*)(SSL *))ssl_sw[25].ptr)
#define SSL_get_current_cipher (*(SSL_CIPHER * (*)(SSL *))ssl_sw[26].ptr)
#define SSL_CIPHER_get_name                                                    \
        (*(const char *(*)(const SSL_CIPHER *))ssl_sw[27].ptr)
#define SSL_CTX_check_private_key (*(int (*)(SSL_CTX *))ssl_sw[28].ptr)
#define SSL_CTX_set_session_id_context                                         \
        (*(int (*)(SSL_CTX *, const unsigned char *, unsigned int))ssl_sw[29].ptr)
#define SSL_CTX_ctrl (*(long (*)(SSL_CTX *, int, long, void *))ssl_sw[30].ptr)
#define SSL_CTX_set_cipher_list                                                \
        (*(int (*)(SSL_CTX *, const char *))ssl_sw[31].ptr)
#define SSL_CTX_set_options(ctx, op)                                           \
        SSL_CTX_ctrl((ctx), SSL_CTRL_OPTIONS, (op), NULL)
#define SSL_CTX_clear_options(ctx, op)                                         \
        SSL_CTX_ctrl((ctx), SSL_CTRL_CLEAR_OPTIONS, (op), NULL)
#define SSL_CTX_set_ecdh_auto(ctx, onoff)                                      \
        SSL_CTX_ctrl(ctx, SSL_CTRL_SET_ECDH_AUTO, onoff, NULL)

#define CRYPTO_num_locks (*(int (*)(void))crypto_sw[0].ptr)
#define CRYPTO_set_locking_callback                                            \
        (*(void (*)(void (*)(int, int, const char *, int)))crypto_sw[1].ptr)
#define CRYPTO_set_id_callback                                                 \
        (*(void (*)(unsigned long (*)(void)))crypto_sw[2].ptr)
#define ERR_get_error (*(unsigned long (*)(void))crypto_sw[3].ptr)
#define ERR_error_string (*(char *(*)(unsigned long, char *))crypto_sw[4].ptr)
#define ERR_remove_state (*(void (*)(unsigned long))crypto_sw[5].ptr)
#define ERR_free_strings (*(void (*)(void))crypto_sw[6].ptr)
#define ENGINE_cleanup (*(void (*)(void))crypto_sw[7].ptr)
#define CONF_modules_unload (*(void (*)(int))crypto_sw[8].ptr)
#define CRYPTO_cleanup_all_ex_data (*(void (*)(void))crypto_sw[9].ptr)
#define EVP_cleanup (*(void (*)(void))crypto_sw[10].ptr)


/* set_ssl_option() function updates this array.
 * It loads SSL library dynamically and changes NULLs to the actual addresses
 * of respective functions. The macros above (like SSL_connect()) are really
 * just calling these functions indirectly via the pointer. */
static struct ssl_func ssl_sw[] = {{"SSL_free", NULL},
                                   {"SSL_accept", NULL},
                                   {"SSL_connect", NULL},
                                   {"SSL_read", NULL},
                                   {"SSL_write", NULL},
                                   {"SSL_get_error", NULL},
                                   {"SSL_set_fd", NULL},
                                   {"SSL_new", NULL},
                                   {"SSL_CTX_new", NULL},
                                   {"SSLv23_server_method", NULL},
                                   {"SSL_library_init", NULL},
                                   {"SSL_CTX_use_PrivateKey_file", NULL},
                                   {"SSL_CTX_use_certificate_file", NULL},
                                   {"SSL_CTX_set_default_passwd_cb", NULL},
                                   {"SSL_CTX_free", NULL},
                                   {"SSL_load_error_strings", NULL},
                                   {"SSL_CTX_use_certificate_chain_file", NULL},
                                   {"SSLv23_client_method", NULL},
                                   {"SSL_pending", NULL},
                                   {"SSL_CTX_set_verify", NULL},
                                   {"SSL_shutdown", NULL},
                                   {"SSL_CTX_load_verify_locations", NULL},
                                   {"SSL_CTX_set_default_verify_paths", NULL},
                                   {"SSL_CTX_set_verify_depth", NULL},
                                   {"SSL_get_peer_certificate", NULL},
                                   {"SSL_get_version", NULL},
                                   {"SSL_get_current_cipher", NULL},
                                   {"SSL_CIPHER_get_name", NULL},
                                   {"SSL_CTX_check_private_key", NULL},
                                   {"SSL_CTX_set_session_id_context", NULL},
                                   {"SSL_CTX_ctrl", NULL},
                                   {"SSL_CTX_set_cipher_list", NULL},
                                   {NULL, NULL}};


/* Similar array as ssl_sw. These functions could be located in different
 * lib. */
#if !defined(NO_SSL)
static struct ssl_func crypto_sw[] = {{"CRYPTO_num_locks", NULL},
                                      {"CRYPTO_set_locking_callback", NULL},
                                      {"CRYPTO_set_id_callback", NULL},
                                      {"ERR_get_error", NULL},
                                      {"ERR_error_string", NULL},
                                      {"ERR_remove_state", NULL},
                                      {"ERR_free_strings", NULL},
                                      {"ENGINE_cleanup", NULL},
                                      {"CONF_modules_unload", NULL},
                                      {"CRYPTO_cleanup_all_ex_data", NULL},
                                      {"EVP_cleanup", NULL},
                                      {NULL, NULL}};
#endif /* NO_SSL */
#endif /* NO_SSL_DL */


#if !defined(NO_CACHING)
static const char *month_names[] = {"Jan",
                                    "Feb",
                                    "Mar",
                                    "Apr",
                                    "May",
                                    "Jun",
                                    "Jul",
                                    "Aug",
                                    "Sep",
                                    "Oct",
                                    "Nov",
                                    "Dec"};
#endif /* !NO_CACHING */

/* Unified socket address. For IPv6 support, add IPv6 address structure in the
 * union u. */
union usa {
        struct sockaddr sa;
        struct sockaddr_in sin;
#if defined(USE_IPV6)
        struct sockaddr_in6 sin6;
#endif
};

/* Describes a string (chunk of memory). */
struct vec {
        const char *ptr;
        size_t len;
};

struct file {
        uint64_t size;
        time_t last_modified;
        FILE *fp;
        const char *membuf; /* Non-NULL if file data is in memory */
        int is_directory;
        int gzipped; /* set to 1 if the content is gzipped
                      * in which case we need a content-encoding: gzip header */
};

#define STRUCT_FILE_INITIALIZER                                                \
        {                                                                          \
                (uint64_t)0, (time_t)0, (FILE *)NULL, (const char *)NULL, 0, 0         \
        }

/* Describes listening socket, or socket which was accept()-ed by the master
 * thread and queued for future handling by the worker thread. */
struct socket {
        SOCKET sock;             /* Listening socket */
        union usa lsa;           /* Local socket address */
        union usa rsa;           /* Remote socket address */
        unsigned char is_ssl;    /* Is port SSL-ed */
        unsigned char ssl_redir; /* Is port supposed to redirect everything to SSL
                                  * port */
};

/* NOTE(lsm): this enum shoulds be in sync with the config_options below. */
enum {
        CGI_EXTENSIONS,
        CGI_ENVIRONMENT,
        PUT_DELETE_PASSWORDS_FILE,
        CGI_INTERPRETER,
        PROTECT_URI,
        AUTHENTICATION_DOMAIN,
        ENABLE_AUTH_DOMAIN_CHECK,
        SSI_EXTENSIONS,
        THROTTLE,
        ACCESS_LOG_FILE,
        ENABLE_DIRECTORY_LISTING,
        ERROR_LOG_FILE,
        GLOBAL_PASSWORDS_FILE,
        INDEX_FILES,
        ENABLE_KEEP_ALIVE,
        ACCESS_CONTROL_LIST,
        EXTRA_MIME_TYPES,
        LISTENING_PORTS,
        DOCUMENT_ROOT,
        SSL_CERTIFICATE,
        NUM_THREADS,
        RUN_AS_USER,
        REWRITE,
        HIDE_FILES,
        REQUEST_TIMEOUT,
        SSL_DO_VERIFY_PEER,
        SSL_CA_PATH,
        SSL_CA_FILE,
        SSL_VERIFY_DEPTH,
        SSL_DEFAULT_VERIFY_PATHS,
        SSL_CIPHER_LIST,
        SSL_PROTOCOL_VERSION,
        SSL_SHORT_TRUST,
#if defined(USE_WEBSOCKET)
        WEBSOCKET_TIMEOUT,
#endif
        DECODE_URL,

#if defined(USE_LUA)
        LUA_PRELOAD_FILE,
        LUA_SCRIPT_EXTENSIONS,
        LUA_SERVER_PAGE_EXTENSIONS,
#endif
#if defined(USE_DUKTAPE)
        DUKTAPE_SCRIPT_EXTENSIONS,
#endif

#if defined(USE_WEBSOCKET)
        WEBSOCKET_ROOT,
#endif
#if defined(USE_LUA) && defined(USE_WEBSOCKET)
        LUA_WEBSOCKET_EXTENSIONS,
#endif
        ACCESS_CONTROL_ALLOW_ORIGIN,
        ERROR_PAGES,
        CONFIG_TCP_NODELAY, /* Prepended CONFIG_ to avoid conflict with the
                         * socket option typedef TCP_NODELAY. */
#if !defined(NO_CACHING)
        STATIC_FILE_MAX_AGE,
#endif
        VALIDATE_HTTP_METHOD,
        CANONICALIZE_URL_PATH,

        NUM_OPTIONS
};


/* Config option name, config types, default value */
static struct mg_option config_options[] = {
    {"cgi_pattern", CONFIG_TYPE_EXT_PATTERN, "**.cgi$|**.pl$|**.php$"},
    {"cgi_environment", CONFIG_TYPE_STRING, NULL},
    {"put_delete_auth_file", CONFIG_TYPE_FILE, NULL},
    {"cgi_interpreter", CONFIG_TYPE_FILE, NULL},
    {"protect_uri", CONFIG_TYPE_STRING, NULL},
    {"authentication_domain", CONFIG_TYPE_STRING, "mydomain.com"},
    {"enable_auth_domain_check", CONFIG_TYPE_BOOLEAN, "yes"},
    {"ssi_pattern", CONFIG_TYPE_EXT_PATTERN, "**.shtml$|**.shtm$"},
    {"throttle", CONFIG_TYPE_STRING, NULL},
    {"access_log_file", CONFIG_TYPE_FILE, NULL},
    {"enable_directory_listing", CONFIG_TYPE_BOOLEAN, "yes"},
    {"error_log_file", CONFIG_TYPE_FILE, NULL},
    {"global_auth_file", CONFIG_TYPE_FILE, NULL},
    {"index_files",
     CONFIG_TYPE_STRING,
#ifdef USE_LUA
     "index.xhtml,index.html,index.htm,index.lp,index.lsp,index.lua,index.cgi,"
     "index.shtml,index.php"},
#else
     "index.xhtml,index.html,index.htm,index.cgi,index.shtml,index.php"},
#endif
    {"enable_keep_alive", CONFIG_TYPE_BOOLEAN, "no"},
    {"access_control_list", CONFIG_TYPE_STRING, NULL},
    {"extra_mime_types", CONFIG_TYPE_STRING, NULL},
    {"listening_ports", CONFIG_TYPE_STRING, "8080"},
    {"document_root", CONFIG_TYPE_DIRECTORY, NULL},
    {"ssl_certificate", CONFIG_TYPE_FILE, NULL},
    {"num_threads", CONFIG_TYPE_NUMBER, "50"},
    {"run_as_user", CONFIG_TYPE_STRING, NULL},
    {"url_rewrite_patterns", CONFIG_TYPE_STRING, NULL},
    {"hide_files_patterns", CONFIG_TYPE_EXT_PATTERN, NULL},
    {"request_timeout_ms", CONFIG_TYPE_NUMBER, "30000"},
    {"ssl_verify_peer", CONFIG_TYPE_BOOLEAN, "no"},
    {"ssl_ca_path", CONFIG_TYPE_DIRECTORY, NULL},
    {"ssl_ca_file", CONFIG_TYPE_FILE, NULL},
    {"ssl_verify_depth", CONFIG_TYPE_NUMBER, "9"},
    {"ssl_default_verify_paths", CONFIG_TYPE_BOOLEAN, "yes"},
    {"ssl_cipher_list", CONFIG_TYPE_STRING, NULL},
    {"ssl_protocol_version", CONFIG_TYPE_NUMBER, "0"},
    {"ssl_short_trust", CONFIG_TYPE_BOOLEAN, "no"},
#if defined(USE_WEBSOCKET)
    {"websocket_timeout_ms", CONFIG_TYPE_NUMBER, "30000"},
#endif
    {"decode_url", CONFIG_TYPE_BOOLEAN, "yes"},

#if defined(USE_LUA)
    {"lua_preload_file", CONFIG_TYPE_FILE, NULL},
    {"lua_script_pattern", CONFIG_TYPE_EXT_PATTERN, "**.lua$"},
    {"lua_server_page_pattern", CONFIG_TYPE_EXT_PATTERN, "**.lp$|**.lsp$"},
#endif
#if defined(USE_DUKTAPE)
    /* The support for duktape is still in alpha version state.
     * The name of this config option might change. */
    {"duktape_script_pattern", CONFIG_TYPE_EXT_PATTERN, "**.ssjs$"},
#endif

#if defined(USE_WEBSOCKET)
    {"websocket_root", CONFIG_TYPE_DIRECTORY, NULL},
#endif
#if defined(USE_LUA) && defined(USE_WEBSOCKET)
    {"lua_websocket_pattern", CONFIG_TYPE_EXT_PATTERN, "**.lua$"},
#endif
    {"access_control_allow_origin", CONFIG_TYPE_STRING, "*"},
    {"error_pages", CONFIG_TYPE_DIRECTORY, NULL},
    {"tcp_nodelay", CONFIG_TYPE_NUMBER, "0"},
#if !defined(NO_CACHING)
    {"static_file_max_age", CONFIG_TYPE_NUMBER, "3600"},
#endif
    {"validate_http_method", CONFIG_TYPE_BOOLEAN, "yes"},
    {"canonicalize_url_path", CONFIG_TYPE_BOOLEAN, "yes"},

    {NULL, CONFIG_TYPE_UNKNOWN, NULL}};

/* Check if the config_options and the corresponding enum have compatible
 * sizes. */
mg_static_assert((sizeof(config_options) / sizeof(config_options[0]))
                     == (NUM_OPTIONS + 1),
                 "config_options and enum not sync");

enum { REQUEST_HANDLER, WEBSOCKET_HANDLER, AUTH_HANDLER };

struct mg_handler_info {
        /* Name/Pattern of the URI. */
        char *uri;
        size_t uri_len;

        /* handler type */
        int handler_type;

        /* Handler for http/https or authorization requests. */
        mg_request_handler handler;

        /* Handler for ws/wss (websocket) requests. */
        mg_websocket_connect_handler connect_handler;
        mg_websocket_ready_handler ready_handler;
        mg_websocket_data_handler data_handler;
        mg_websocket_close_handler close_handler;

        /* Handler for authorization requests */
        mg_authorization_handler auth_handler;

        /* User supplied argument for the handler function. */
        void *cbdata;

        /* next handler in a linked list */
        struct mg_handler_info *next;
};

struct mg_context {
        volatile int stop_flag;        /* Should we stop event loop */
        SSL_CTX *ssl_ctx;              /* SSL context */
        char *config[NUM_OPTIONS];     /* Civetweb configuration parameters */
        struct mg_callbacks callbacks; /* User-defined callback function */
        void *user_data;               /* User-defined data */
        int context_type;              /* 1 = server context, 2 = client context */

        struct socket *listening_sockets;
        in_port_t *listening_ports;
        unsigned int num_listening_sockets;

        volatile int
            running_worker_threads; /* Number of currently running worker threads */
        pthread_mutex_t thread_mutex; /* Protects (max|num)_threads */
        pthread_cond_t thread_cond; /* Condvar for tracking workers terminations */

        struct socket queue[MGSQLEN]; /* Accepted sockets */
        volatile int sq_head;         /* Head of the socket queue */
        volatile int sq_tail;         /* Tail of the socket queue */
        pthread_cond_t sq_full;       /* Signaled when socket is produced */
        pthread_cond_t sq_empty;      /* Signaled when socket is consumed */
        pthread_t masterthreadid;     /* The master thread ID */
        unsigned int
            cfg_worker_threads;     /* The number of configured worker threads. */
        pthread_t *workerthreadids; /* The worker thread IDs */

        time_t start_time;        /* Server start time, used for authentication */
        uint64_t auth_nonce_mask; /* Mask for all nonce values */
        pthread_mutex_t nonce_mutex; /* Protects nonce_count */
        unsigned long nonce_count;   /* Used nonces, used for authentication */

        char *systemName; /* What operating system is running */

        /* linked list of uri handlers */
        struct mg_handler_info *handlers;

#if defined(USE_LUA) && defined(USE_WEBSOCKET)
        /* linked list of shared lua websockets */
        struct mg_shared_lua_websocket_list *shared_lua_websockets;
#endif

#ifdef USE_TIMERS
        struct ttimers *timers;
#endif
};


struct mg_connection {
        struct mg_request_info request_info;
        struct mg_context *ctx;
        SSL *ssl;                 /* SSL descriptor */
        SSL_CTX *client_ssl_ctx;  /* SSL context for client connections */
        struct socket client;     /* Connected client */
        time_t conn_birth_time;   /* Time (wall clock) when connection was
                                   * established */
        struct timespec req_time; /* Time (since system start) when the request
                                   * was received */
        int64_t num_bytes_sent;   /* Total bytes sent to client */
        int64_t content_len;      /* Content-Length header value */
        int64_t consumed_content; /* How many bytes of content have been read */
        int is_chunked;           /* Transfer-Encoding is chunked: 0=no, 1=yes:
                                   * data available, 2: all data read */
        size_t chunk_remainder;   /* Unread data from the last chunk */
        char *buf;                /* Buffer for received data */
        char *path_info;          /* PATH_INFO part of the URL */

        int must_close;       /* 1 if connection must be closed */
        int in_error_handler; /* 1 if in handler for user defined error
                               * pages */
        int internal_error;   /* 1 if an error occured while processing the
                               * request */

        int buf_size;                /* Buffer size */
        int request_len;             /* Size of the request + headers in a buffer */
        int data_len;                /* Total size of data in a buffer */
        int status_code;             /* HTTP reply status code, e.g. 200 */
        int throttle;                /* Throttling, bytes/sec. <= 0 means no
                                      * throttle */
        time_t last_throttle_time;   /* Last time throttled data was sent */
        int64_t last_throttle_bytes; /* Bytes sent this second */
        pthread_mutex_t mutex;       /* Used by mg_(un)lock_connection to ensure
                                      * atomic transmissions for websockets */
#if defined(USE_LUA) && defined(USE_WEBSOCKET)
        void *lua_websocket_state; /* Lua_State for a websocket connection */
#endif
};


static pthread_key_t sTlsKey; /* Thread local storage index */
static int sTlsInit = 0;
static int thread_idx_max = 0;


struct mg_workerTLS {
        int is_master;
        unsigned long thread_idx;
#if defined(_WIN32) && !defined(__SYMBIAN32__)
        HANDLE pthread_cond_helper_mutex;
#endif
};

/* Directory entry */
struct de {
        struct mg_connection *conn;
        char *file_name;
        struct file file;
};


#if defined(USE_WEBSOCKET)
static int is_websocket_protocol(const struct mg_connection *conn);
#else
#define is_websocket_protocol(conn) (0)
#endif


static int
mg_atomic_inc(volatile int *addr)
{
        int ret;
#if defined(_WIN32) && !defined(__SYMBIAN32__)
        /* Depending on the SDK, this function uses either
         * (volatile unsigned int *) or (volatile LONG *),
         * so whatever you use, the other SDK is likely to raise a warning. */
        ret = InterlockedIncrement((volatile long *)addr);
#elif defined(__GNUC__)                                                        \
    && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 0)))
        ret = __sync_add_and_fetch(addr, 1);
#else
        ret = (++(*addr));
#endif
        return ret;
}


static int
mg_atomic_dec(volatile int *addr)
{
        int ret;
#if defined(_WIN32) && !defined(__SYMBIAN32__)
        /* Depending on the SDK, this function uses either
         * (volatile unsigned int *) or (volatile LONG *),
         * so whatever you use, the other SDK is likely to raise a warning. */
        ret = InterlockedDecrement((volatile long *)addr);
#elif defined(__GNUC__)                                                        \
    && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 0)))
        ret = __sync_sub_and_fetch(addr, 1);
#else
        ret = (--(*addr));
#endif
        return ret;
}

#if !defined(NO_THREAD_NAME)
#if defined(_WIN32) && defined(_MSC_VER)
/* Set the thread name for debugging purposes in Visual Studio
 * http://msdn.microsoft.com/en-us/library/xcb2z8hs.aspx
 */
#pragma pack(push, 8)
typedef struct tagTHREADNAME_INFO {
        DWORD dwType;     /* Must be 0x1000. */
        LPCSTR szName;    /* Pointer to name (in user addr space). */
        DWORD dwThreadID; /* Thread ID (-1=caller thread). */
        DWORD dwFlags;    /* Reserved for future use, must be zero. */
} THREADNAME_INFO;
#pragma pack(pop)
#elif defined(__linux__)
#include <sys/prctl.h>
#include <sys/sendfile.h>
#endif


static void
mg_set_thread_name(const char *name)
{
        char threadName[16 + 1]; /* 16 = Max. thread length in Linux/OSX/.. */

        mg_snprintf(
            NULL, NULL, threadName, sizeof(threadName), "civetweb-%s", name);

#if defined(_WIN32)
#if defined(_MSC_VER)
        /* Windows and Visual Studio Compiler */
        __try
        {
                THREADNAME_INFO info;
                info.dwType = 0x1000;
                info.szName = threadName;
                info.dwThreadID = ~0U;
                info.dwFlags = 0;

                RaiseException(0x406D1388,
                               0,
                               sizeof(info) / sizeof(ULONG_PTR),
                               (ULONG_PTR *)&info);
        }
        __except(EXCEPTION_EXECUTE_HANDLER)
        {
        }
#elif defined(__MINGW32__)
/* No option known to set thread name for MinGW */
#endif
#elif defined(__GLIBC__)                                                       \
    && ((__GLIBC__ > 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 12)))
        /* pthread_setname_np first appeared in glibc in version 2.12*/
        (void)pthread_setname_np(pthread_self(), threadName);
#elif defined(__linux__)
        /* on linux we can use the old prctl function */
        (void)prctl(PR_SET_NAME, threadName, 0, 0, 0);
#endif
}
#else /* !defined(NO_THREAD_NAME) */
void
mg_set_thread_name(const char *threadName)
{
}
#endif


#if defined(MG_LEGACY_INTERFACE)
const char **
mg_get_valid_option_names(void)
{
        /* This function is deprecated. Use mg_get_valid_options instead. */
        static const char *
            data[2 * sizeof(config_options) / sizeof(config_options[0])] = {0};
        int i;

        for (i = 0; config_options[i].name != NULL; i++) {
                data[i * 2] = config_options[i].name;
                data[i * 2 + 1] = config_options[i].default_value;
        }

        return data;
}
#endif


const struct mg_option *
mg_get_valid_options(void)
{
        return config_options;
}


static int
is_file_in_memory(const struct mg_connection *conn,
                  const char *path,
                  struct file *filep)
{
        size_t size = 0;
        if (!conn || !filep) {
                return 0;
        }

        if (conn->ctx->callbacks.open_file) {
                filep->membuf = conn->ctx->callbacks.open_file(conn, path, &size);
                if (filep->membuf != NULL) {
                        /* NOTE: override filep->size only on success. Otherwise, it might
                         * break constructs like if (!mg_stat() || !mg_fopen()) ... */
                        filep->size = size;
                }
        }

        return filep->membuf != NULL;
}


static int
is_file_opened(const struct file *filep)
{
        if (!filep) {
                return 0;
        }

        return filep->membuf != NULL || filep->fp != NULL;
}


/* mg_fopen will open a file either in memory or on the disk.
 * The input parameter path is a string in UTF-8 encoding.
 * The input parameter mode is the same as for fopen.
 * Either fp or membuf will be set in the output struct filep.
 * The function returns 1 on success, 0 on error. */
static int
mg_fopen(const struct mg_connection *conn,
         const char *path,
         const char *mode,
         struct file *filep)
{
        struct stat st;

        if (!filep) {
                return 0;
        }

        /* TODO (high): mg_fopen should only open a file, while mg_stat should
         * only get the file status. They should not work on different members of
         * the same structure (bad cohesion). */
        memset(filep, 0, sizeof(*filep));

        if (stat(path, &st) == 0) {
                filep->size = (uint64_t)(st.st_size);
        }

        if (!is_file_in_memory(conn, path, filep)) {
#ifdef _WIN32
                wchar_t wbuf[PATH_MAX], wmode[20];
                path_to_unicode(conn, path, wbuf, ARRAY_SIZE(wbuf));
                MultiByteToWideChar(CP_UTF8, 0, mode, -1, wmode, ARRAY_SIZE(wmode));
                filep->fp = _wfopen(wbuf, wmode);
#else
                /* Linux et al already use unicode. No need to convert. */
                filep->fp = fopen(path, mode);
#endif
        }

        return is_file_opened(filep);
}


static void
mg_fclose(struct file *filep)
{
        if (filep != NULL && filep->fp != NULL) {
                fclose(filep->fp);
        }
}


static void
mg_strlcpy(register char *dst, register const char *src, size_t n)
{
        for (; *src != '\0' && n > 1; n--) {
                *dst++ = *src++;
        }
        *dst = '\0';
}


static int
lowercase(const char *s)
{
        return tolower(*(const unsigned char *)s);
}


int
mg_strncasecmp(const char *s1, const char *s2, size_t len)
{
        int diff = 0;

        if (len > 0) {
                do {
                        diff = lowercase(s1++) - lowercase(s2++);
                } while (diff == 0 && s1[-1] != '\0' && --len > 0);
        }

        return diff;
}


int
mg_strcasecmp(const char *s1, const char *s2)
{
        int diff;

        do {
                diff = lowercase(s1++) - lowercase(s2++);
        } while (diff == 0 && s1[-1] != '\0');

        return diff;
}


static char *
mg_strndup(const char *ptr, size_t len)
{
        char *p;

        if ((p = (char *)mg_malloc(len + 1)) != NULL) {
                mg_strlcpy(p, ptr, len + 1);
        }

        return p;
}


static char *
mg_strdup(const char *str)
{
        return mg_strndup(str, strlen(str));
}


static const char *
mg_strcasestr(const char *big_str, const char *small_str)
{
        size_t i, big_len = strlen(big_str), small_len = strlen(small_str);

        if (big_len >= small_len) {
                for (i = 0; i <= (big_len - small_len); i++) {
                        if (mg_strncasecmp(big_str + i, small_str, small_len) == 0) {
                                return big_str + i;
                        }
                }
        }

        return NULL;
}


/* Return null terminated string of given maximum length.
 * Report errors if length is exceeded. */
static void
mg_vsnprintf(const struct mg_connection *conn,
             int *truncated,
             char *buf,
             size_t buflen,
             const char *fmt,
             va_list ap)
{
        int n, ok;

        if (buflen == 0) {
                return;
        }

#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wformat-nonliteral"
/* Using fmt as a non-literal is intended here, since it is mostly called
 * indirectly by mg_snprintf */
#endif

        n = (int)vsnprintf_impl(buf, buflen, fmt, ap);
        ok = (n >= 0) && ((size_t)n < buflen);

#ifdef __clang__
#pragma clang diagnostic pop
#endif

        if (ok) {
                if (truncated) {
                        *truncated = 0;
                }
        } else {
                if (truncated) {
                        *truncated = 1;
                }
                mg_cry(conn,
                       "truncating vsnprintf buffer: [%.*s]",
                       (int)((buflen > 200) ? 200 : (buflen - 1)),
                       buf);
                n = (int)buflen - 1;
        }
        buf[n] = '\0';
}


static void
mg_snprintf(const struct mg_connection *conn,
            int *truncated,
            char *buf,
            size_t buflen,
            const char *fmt,
            ...)
{
        va_list ap;

        va_start(ap, fmt);
        mg_vsnprintf(conn, truncated, buf, buflen, fmt, ap);
        va_end(ap);
}


static int
get_option_index(const char *name)
{
        int i;

        for (i = 0; config_options[i].name != NULL; i++) {
                if (strcmp(config_options[i].name, name) == 0) {
                        return i;
                }
        }
        return -1;
}


const char *
mg_get_option(const struct mg_context *ctx, const char *name)
{
        int i;
        if ((i = get_option_index(name)) == -1) {
                return NULL;
        } else if (!ctx || ctx->config[i] == NULL) {
                return "";
        } else {
                return ctx->config[i];
        }
}


struct mg_context *
mg_get_context(const struct mg_connection *conn)
{
        return (conn == NULL) ? (struct mg_context *)NULL : (conn->ctx);
}


void *
mg_get_user_data(const struct mg_context *ctx)
{
        return (ctx == NULL) ? NULL : ctx->user_data;
}


void
mg_set_user_connection_data(struct mg_connection *conn, void *data)
{
        if (conn != NULL) {
                conn->request_info.conn_data = data;
        }
}


void *
mg_get_user_connection_data(const struct mg_connection *conn)
{
        if (conn != NULL) {
                return conn->request_info.conn_data;
        }
        return NULL;
}


size_t
mg_get_ports(const struct mg_context *ctx, size_t size, int *ports, int *ssl)
{
        size_t i;
        if (!ctx) {
                return 0;
        }
        for (i = 0; i < size && i < ctx->num_listening_sockets; i++) {
                ssl[i] = ctx->listening_sockets[i].is_ssl;
                ports[i] = ctx->listening_ports[i];
        }
        return i;
}


int
mg_get_server_ports(const struct mg_context *ctx,
                    int size,
                    struct mg_server_ports *ports)
{
        int i, cnt = 0;

        if (size <= 0) {
                return -1;
        }
        memset(ports, 0, sizeof(*ports) * (size_t)size);
        if (!ctx) {
                return -1;
        }
        if (!ctx->listening_sockets || !ctx->listening_ports) {
                return -1;
        }

        for (i = 0; (i < size) && (i < (int)ctx->num_listening_sockets); i++) {

                ports[cnt].port = ctx->listening_ports[i];
                ports[cnt].is_ssl = ctx->listening_sockets[i].is_ssl;
                ports[cnt].is_redirect = ctx->listening_sockets[i].ssl_redir;

                if (ctx->listening_sockets[i].lsa.sa.sa_family == AF_INET) {
                        /* IPv4 */
                        ports[cnt].protocol = 1;
                        cnt++;
                } else if (ctx->listening_sockets[i].lsa.sa.sa_family == AF_INET6) {
                        /* IPv6 */
                        ports[cnt].protocol = 3;
                        cnt++;
                }
        }

        return cnt;
}


static void
sockaddr_to_string(char *buf, size_t len, const union usa *usa)
{
        buf[0] = '\0';

        if (!usa) {
                return;
        }

        if (usa->sa.sa_family == AF_INET) {
                getnameinfo(&usa->sa,
                            sizeof(usa->sin),
                            buf,
                            (unsigned)len,
                            NULL,
                            0,
                            NI_NUMERICHOST);
        }
#if defined(USE_IPV6)
        else if (usa->sa.sa_family == AF_INET6) {
                getnameinfo(&usa->sa,
                            sizeof(usa->sin6),
                            buf,
                            (unsigned)len,
                            NULL,
                            0,
                            NI_NUMERICHOST);
        }
#endif
}


/* Convert time_t to a string. According to RFC2616, Sec 14.18, this must be
 * included in all responses other than 100, 101, 5xx. */
static void
gmt_time_string(char *buf, size_t buf_len, time_t *t)
{
        struct tm *tm;

        tm = ((t != NULL) ? gmtime(t) : NULL);
        if (tm != NULL) {
                strftime(buf, buf_len, "%a, %d %b %Y %H:%M:%S GMT", tm);
        } else {
                mg_strlcpy(buf, "Thu, 01 Jan 1970 00:00:00 GMT", buf_len);
                buf[buf_len - 1] = '\0';
        }
}


/* difftime for struct timespec. Return value is in seconds. */
static double
mg_difftimespec(const struct timespec *ts_now, const struct timespec *ts_before)
{
        return (double)(ts_now->tv_nsec - ts_before->tv_nsec) * 1.0E-9
               + (double)(ts_now->tv_sec - ts_before->tv_sec);
}


/* Print error message to the opened error log stream. */
void
mg_cry(const struct mg_connection *conn, const char *fmt, ...)
{
        char buf[MG_BUF_LEN], src_addr[IP_ADDR_STR_LEN];
        va_list ap;
        struct file fi;
        time_t timestamp;

        va_start(ap, fmt);
        IGNORE_UNUSED_RESULT(vsnprintf_impl(buf, sizeof(buf), fmt, ap));
        va_end(ap);
        buf[sizeof(buf) - 1] = 0;

        if (!conn) {
                puts(buf);
                return;
        }

        /* Do not lock when getting the callback value, here and below.
         * I suppose this is fine, since function cannot disappear in the
         * same way string option can. */
        if ((conn->ctx->callbacks.log_message == NULL)
            || (conn->ctx->callbacks.log_message(conn, buf) == 0)) {

                if (conn->ctx->config[ERROR_LOG_FILE] != NULL) {
                        if (mg_fopen(conn, conn->ctx->config[ERROR_LOG_FILE], "a+", &fi)
                            == 0) {
                                fi.fp = NULL;
                        }
                } else {
                        fi.fp = NULL;
                }

                if (fi.fp != NULL) {
                        flockfile(fi.fp);
                        timestamp = time(NULL);

                        sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);
                        fprintf(fi.fp,
                                "[%010lu] [error] [client %s] ",
                                (unsigned long)timestamp,
                                src_addr);

                        if (conn->request_info.request_method != NULL) {
                                fprintf(fi.fp,
                                        "%s %s: ",
                                        conn->request_info.request_method,
                                        conn->request_info.request_uri);
                        }

                        fprintf(fi.fp, "%s", buf);
                        fputc('\n', fi.fp);
                        fflush(fi.fp);
                        funlockfile(fi.fp);
                        mg_fclose(&fi);
                }
        }
}

void
mg_set_http_status(struct mg_connection *conn, int status)
{
        conn->status_code = status;
}

/* Return fake connection structure. Used for logging, if connection
 * is not applicable at the moment of logging. */
static struct mg_connection *
fc(struct mg_context *ctx)
{
        static struct mg_connection fake_connection;
        fake_connection.ctx = ctx;
        return &fake_connection;
}


const char *
mg_version(void)
{
        return CIVETWEB_VERSION;
}


const struct mg_request_info *
mg_get_request_info(const struct mg_connection *conn)
{
        if (!conn) {
                return NULL;
        }
        return &conn->request_info;
}


struct sockaddr *
mg_get_local_addr(struct mg_connection *conn)
{
    return &conn->client.lsa.sa;
}


/* Skip the characters until one of the delimiters characters found.
 * 0-terminate resulting word. Skip the delimiter and following whitespaces.
 * Advance pointer to buffer to the next word. Return found 0-terminated word.
 * Delimiters can be quoted with quotechar. */
static char *
skip_quoted(char **buf,
            const char *delimiters,
            const char *whitespace,
            char quotechar)
{
        char *p, *begin_word, *end_word, *end_whitespace;

        begin_word = *buf;
        end_word = begin_word + strcspn(begin_word, delimiters);

        /* Check for quotechar */
        if (end_word > begin_word) {
                p = end_word - 1;
                while (*p == quotechar) {
                        /* While the delimiter is quoted, look for the next delimiter. */
                        /* This happens, e.g., in calls from parse_auth_header,
                         * if the user name contains a " character. */

                        /* If there is anything beyond end_word, copy it. */
                        if (*end_word != '\0') {
                                size_t end_off = strcspn(end_word + 1, delimiters);
                                memmove(p, end_word, end_off + 1);
                                p += end_off; /* p must correspond to end_word - 1 */
                                end_word += end_off + 1;
                        } else {
                                *p = '\0';
                                break;
                        }
                }
                for (p++; p < end_word; p++) {
                        *p = '\0';
                }
        }

        if (*end_word == '\0') {
                *buf = end_word;
        } else {
                end_whitespace = end_word + 1 + strspn(end_word + 1, whitespace);

                for (p = end_word; p < end_whitespace; p++) {
                        *p = '\0';
                }

                *buf = end_whitespace;
        }

        return begin_word;
}


/* Simplified version of skip_quoted without quote char
 * and whitespace == delimiters */
static char *
skip(char **buf, const char *delimiters)
{
        return skip_quoted(buf, delimiters, delimiters, 0);
}


/* Return HTTP header value, or NULL if not found. */
static const char *
get_header(const struct mg_request_info *ri, const char *name)
{
        int i;
        if (ri) {
                for (i = 0; i < ri->num_headers; i++) {
                        if (!mg_strcasecmp(name, ri->http_headers[i].name)) {
                                return ri->http_headers[i].value;
                        }
                }
        }

        return NULL;
}


const char *
mg_get_header(const struct mg_connection *conn, const char *name)
{
        if (!conn) {
                return NULL;
        }

        return get_header(&conn->request_info, name);
}


/* A helper function for traversing a comma separated list of values.
 * It returns a list pointer shifted to the next value, or NULL if the end
 * of the list found.
 * Value is stored in val vector. If value has form "x=y", then eq_val
 * vector is initialized to point to the "y" part, and val vector length
 * is adjusted to point only to "x". */
static const char *
next_option(const char *list, struct vec *val, struct vec *eq_val)
{
        int end;

reparse:
        if (val == NULL || list == NULL || *list == '\0') {
                /* End of the list */
                list = NULL;
        } else {
                /* Skip over leading LWS */
                while (*list == ' ' || *list == '\t')
                        list++;

                val->ptr = list;
                if ((list = strchr(val->ptr, ',')) != NULL) {
                        /* Comma found. Store length and shift the list ptr */
                        val->len = ((size_t)(list - val->ptr));
                        list++;
                } else {
                        /* This value is the last one */
                        list = val->ptr + strlen(val->ptr);
                        val->len = ((size_t)(list - val->ptr));
                }

                /* Adjust length for trailing LWS */
                end = (int)val->len - 1;
                while (end >= 0 && (val->ptr[end] == ' ' || val->ptr[end] == '\t'))
                        end--;
                val->len = (size_t)(end + 1);

                if (val->len == 0) {
                        /* Ignore any empty entries. */
                        goto reparse;
                }

                if (eq_val != NULL) {
                        /* Value has form "x=y", adjust pointers and lengths
                         * so that val points to "x", and eq_val points to "y". */
                        eq_val->len = 0;
                        eq_val->ptr = (const char *)memchr(val->ptr, '=', val->len);
                        if (eq_val->ptr != NULL) {
                                eq_val->ptr++; /* Skip over '=' character */
                                eq_val->len = ((size_t)(val->ptr - eq_val->ptr)) + val->len;
                                val->len = ((size_t)(eq_val->ptr - val->ptr)) - 1;
                        }
                }
        }

        return list;
}

/* A helper function for checking if a comma separated list of values contains
 * the given option (case insensitvely).
 * 'header' can be NULL, in which case false is returned. */
static int
header_has_option(const char *header, const char *option)
{
        struct vec opt_vec;
        struct vec eq_vec;

        assert(option != NULL);
        assert(option[0] != '\0');

        while ((header = next_option(header, &opt_vec, &eq_vec)) != NULL) {
                if (mg_strncasecmp(option, opt_vec.ptr, opt_vec.len) == 0)
                        return 1;
        }

        return 0;
}

/* Perform case-insensitive match of string against pattern */
static int
match_prefix(const char *pattern, size_t pattern_len, const char *str)
{
        const char *or_str;
        size_t i;
        int j, len, res;

        if ((or_str = (const char *)memchr(pattern, '|', pattern_len)) != NULL) {
                res = match_prefix(pattern, (size_t)(or_str - pattern), str);
                return res > 0 ? res : match_prefix(or_str + 1,
                                                    (size_t)((pattern + pattern_len)
                                                             - (or_str + 1)),
                                                    str);
        }

        for (i = 0, j = 0; i < pattern_len; i++, j++) {
                if (pattern[i] == '?' && str[j] != '\0') {
                        continue;
                } else if (pattern[i] == '$') {
                        return str[j] == '\0' ? j : -1;
                } else if (pattern[i] == '*') {
                        i++;
                        if (pattern[i] == '*') {
                                i++;
                                len = (int)strlen(str + j);
                        } else {
                                len = (int)strcspn(str + j, "/");
                        }
                        if (i == pattern_len) {
                                return j + len;
                        }
                        do {
                                res = match_prefix(pattern + i, pattern_len - i, str + j + len);
                        } while (res == -1 && len-- > 0);
                        return res == -1 ? -1 : j + res + len;
                } else if (lowercase(&pattern[i]) != lowercase(&str[j])) {
                        return -1;
                }
        }
        return j;
}


/* HTTP 1.1 assumes keep alive if "Connection:" header is not set
 * This function must tolerate situations when connection info is not
 * set up, for example if request parsing failed. */
static int
should_keep_alive(const struct mg_connection *conn)
{
        if (conn != NULL) {
                const char *http_version = conn->request_info.http_version;
                const char *header = mg_get_header(conn, "Connection");
                if (conn->must_close || conn->internal_error || conn->status_code == 401
                    || mg_strcasecmp(conn->ctx->config[ENABLE_KEEP_ALIVE], "yes") != 0
                    || (header != NULL && !header_has_option(header, "keep-alive"))
                    || (header == NULL && http_version
                        && 0 != strcmp(http_version, "1.1"))) {
                        return 0;
                }
                return 1;
        }
        return 0;
}


static int
should_decode_url(const struct mg_connection *conn)
{
        if (!conn || !conn->ctx) {
                return 0;
        }

        return (mg_strcasecmp(conn->ctx->config[DECODE_URL], "yes") == 0);
}

static int
should_validate_http_method(const struct mg_connection *conn)
{
        if (!conn || !conn->ctx || !conn->ctx->config[VALIDATE_HTTP_METHOD]) {
                return 1;
        }

        return (mg_strcasecmp(conn->ctx->config[VALIDATE_HTTP_METHOD], "yes") == 0);
}


static const char *
suggest_connection_header(const struct mg_connection *conn)
{
        return should_keep_alive(conn) ? "keep-alive" : "close";
}


static int
send_no_cache_header(struct mg_connection *conn)
{
        /* Send all current and obsolete cache opt-out directives. */
        return mg_printf(conn,
                         "Cache-Control: no-cache, no-store, "
                         "must-revalidate, private, max-age=0\r\n"
                         "Pragma: no-cache\r\n"
                         "Expires: 0\r\n");
}


static int
send_static_cache_header(struct mg_connection *conn)
{
#if !defined(NO_CACHING)
        /* Read the server config to check how long a file may be cached.
         * The configuration is in seconds. */
        int max_age = atoi(conn->ctx->config[STATIC_FILE_MAX_AGE]);
        if (max_age <= 0) {
                /* 0 means "do not cache". All values <0 are reserved
                 * and may be used differently in the future. */
                /* If a file should not be cached, do not only send
                 * max-age=0, but also pragmas and Expires headers. */
                return send_no_cache_header(conn);
        }

        /* Use "Cache-Control: max-age" instead of "Expires" header.
         * Reason: see https://www.mnot.net/blog/2007/05/15/expires_max-age */
        /* See also https://www.mnot.net/cache_docs/ */
        /* According to RFC 2616, Section 14.21, caching times should not exceed
         * one year. A year with 365 days corresponds to 31536000 seconds, a leap
         * year to 31622400 seconds. For the moment, we just send whatever has
         * been configured, still the behavior for >1 year should be considered
         * as undefined. */
        return mg_printf(conn, "Cache-Control: max-age=%u\r\n", (unsigned)max_age);
#else  /* NO_CACHING */
        return send_no_cache_header(conn);
#endif /* !NO_CACHING */
}


static void handle_file_based_request(struct mg_connection *conn,
                                      const char *path,
                                      struct file *filep);

static int
mg_stat(struct mg_connection *conn, const char *path, struct file *filep);


const char *
mg_get_response_code_text(struct mg_connection *conn, int response_code)
{
        /* See IANA HTTP status code assignment:
         * http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
         */

        switch (response_code) {
        /* RFC2616 Section 10.1 - Informational 1xx */
        case 100:
                return "Continue"; /* RFC2616 Section 10.1.1 */
        case 101:
                return "Switching Protocols"; /* RFC2616 Section 10.1.2 */
        case 102:
                return "Processing"; /* RFC2518 Section 10.1 */

        /* RFC2616 Section 10.2 - Successful 2xx */
        case 200:
                return "OK"; /* RFC2616 Section 10.2.1 */
        case 201:
                return "Created"; /* RFC2616 Section 10.2.2 */
        case 202:
                return "Accepted"; /* RFC2616 Section 10.2.3 */
        case 203:
                return "Non-Authoritative Information"; /* RFC2616 Section 10.2.4 */
        case 204:
                return "No Content"; /* RFC2616 Section 10.2.5 */
        case 205:
                return "Reset Content"; /* RFC2616 Section 10.2.6 */
        case 206:
                return "Partial Content"; /* RFC2616 Section 10.2.7 */
        case 207:
                return "Multi-Status"; /* RFC2518 Section 10.2, RFC4918 Section 11.1 */
        case 208:
                return "Already Reported"; /* RFC5842 Section 7.1 */

        case 226:
                return "IM used"; /* RFC3229 Section 10.4.1 */

        /* RFC2616 Section 10.3 - Redirection 3xx */
        case 300:
                return "Multiple Choices"; /* RFC2616 Section 10.3.1 */
        case 301:
                return "Moved Permanently"; /* RFC2616 Section 10.3.2 */
        case 302:
                return "Found"; /* RFC2616 Section 10.3.3 */
        case 303:
                return "See Other"; /* RFC2616 Section 10.3.4 */
        case 304:
                return "Not Modified"; /* RFC2616 Section 10.3.5 */
        case 305:
                return "Use Proxy"; /* RFC2616 Section 10.3.6 */
        case 307:
                return "Temporary Redirect"; /* RFC2616 Section 10.3.8 */
        case 308:
                return "Permanent Redirect"; /* RFC7238 Section 3 */

        /* RFC2616 Section 10.4 - Client Error 4xx */
        case 400:
                return "Bad Request"; /* RFC2616 Section 10.4.1 */
        case 401:
                return "Unauthorized"; /* RFC2616 Section 10.4.2 */
        case 402:
                return "Payment Required"; /* RFC2616 Section 10.4.3 */
        case 403:
                return "Forbidden"; /* RFC2616 Section 10.4.4 */
        case 404:
                return "Not Found"; /* RFC2616 Section 10.4.5 */
        case 405:
                return "Method Not Allowed"; /* RFC2616 Section 10.4.6 */
        case 406:
                return "Not Acceptable"; /* RFC2616 Section 10.4.7 */
        case 407:
                return "Proxy Authentication Required"; /* RFC2616 Section 10.4.8 */
        case 408:
                return "Request Time-out"; /* RFC2616 Section 10.4.9 */
        case 409:
                return "Conflict"; /* RFC2616 Section 10.4.10 */
        case 410:
                return "Gone"; /* RFC2616 Section 10.4.11 */
        case 411:
                return "Length Required"; /* RFC2616 Section 10.4.12 */
        case 412:
                return "Precondition Failed"; /* RFC2616 Section 10.4.13 */
        case 413:
                return "Request Entity Too Large"; /* RFC2616 Section 10.4.14 */
        case 414:
                return "Request-URI Too Large"; /* RFC2616 Section 10.4.15 */
        case 415:
                return "Unsupported Media Type"; /* RFC2616 Section 10.4.16 */
        case 416:
                return "Requested range not satisfiable"; /* RFC2616 Section 10.4.17 */
        case 417:
                return "Expectation Failed"; /* RFC2616 Section 10.4.18 */

        case 421:
                return "Misdirected Request"; /* RFC7540 Section 9.1.2 */
        case 422:
                return "Unproccessable entity"; /* RFC2518 Section 10.3, RFC4918
                                                 * Section 11.2 */
        case 423:
                return "Locked"; /* RFC2518 Section 10.4, RFC4918 Section 11.3 */
        case 424:
                return "Failed Dependency"; /* RFC2518 Section 10.5, RFC4918
                                             * Section 11.4 */

        case 426:
                return "Upgrade Required"; /* RFC 2817 Section 4 */

        case 428:
                return "Precondition Required"; /* RFC 6585, Section 3 */
        case 429:
                return "Too Many Requests"; /* RFC 6585, Section 4 */

        case 431:
                return "Request Header Fields Too Large"; /* RFC 6585, Section 5 */

        case 451:
                return "Unavailable For Legal Reasons"; /* draft-tbray-http-legally-restricted-status-05,
                                                         * Section 3 */

        /* RFC2616 Section 10.5 - Server Error 5xx */
        case 500:
                return "Internal Server Error"; /* RFC2616 Section 10.5.1 */
        case 501:
                return "Not Implemented"; /* RFC2616 Section 10.5.2 */
        case 502:
                return "Bad Gateway"; /* RFC2616 Section 10.5.3 */
        case 503:
                return "Service Unavailable"; /* RFC2616 Section 10.5.4 */
        case 504:
                return "Gateway Time-out"; /* RFC2616 Section 10.5.5 */
        case 505:
                return "HTTP Version not supported"; /* RFC2616 Section 10.5.6 */
        case 506:
                return "Variant Also Negotiates"; /* RFC 2295, Section 8.1 */
        case 507:
                return "Insufficient Storage"; /* RFC2518 Section 10.6, RFC4918
                                                * Section 11.5 */
        case 508:
                return "Loop Detected"; /* RFC5842 Section 7.1 */

        case 510:
                return "Not Extended"; /* RFC 2774, Section 7 */
        case 511:
                return "Network Authentication Required"; /* RFC 6585, Section 6 */

        /* Other status codes, not shown in the IANA HTTP status code assignment.
         * E.g., "de facto" standards due to common use, ... */
        case 418:
                return "I am a teapot"; /* RFC2324 Section 2.3.2 */
        case 419:
                return "Authentication Timeout"; /* common use */
        case 420:
                return "Enhance Your Calm"; /* common use */
        case 440:
                return "Login Timeout"; /* common use */
        case 509:
                return "Bandwidth Limit Exceeded"; /* common use */

        default:
                /* This error code is unknown. This should not happen. */
                if (conn) {
                        mg_cry(conn, "Unknown HTTP response code: %u", response_code);
                }

                /* Return at least a category according to RFC 2616 Section 10. */
                if (response_code >= 100 && response_code < 200) {
                        /* Unknown informational status code */
                        return "Information";
                }
                if (response_code >= 200 && response_code < 300) {
                        /* Unknown success code */
                        return "Success";
                }
                if (response_code >= 300 && response_code < 400) {
                        /* Unknown redirection code */
                        return "Redirection";
                }
                if (response_code >= 400 && response_code < 500) {
                        /* Unknown request error code */
                        return "Client Error";
                }
                if (response_code >= 500 && response_code < 600) {
                        /* Unknown server error code */
                        return "Server Error";
                }

                /* Response code not even within reasonable range */
                return "";
        }
}


static void send_http_error(struct mg_connection *,
                            int,
                            PRINTF_FORMAT_STRING(const char *fmt),
                            ...) PRINTF_ARGS(3, 4);

static void
send_http_error(struct mg_connection *conn, int status, const char *fmt, ...)
{
        char buf[MG_BUF_LEN];
        va_list ap;
        int len, i, page_handler_found, scope, truncated;
        char date[64];
        time_t curtime = time(NULL);
        const char *error_handler = NULL;
        struct file error_page_file = STRUCT_FILE_INITIALIZER;
        const char *error_page_file_ext, *tstr;

        const char *status_text = mg_get_response_code_text(conn, status);

        if (conn == NULL) {
                return;
        }

        conn->status_code = status;
        if (conn->in_error_handler || conn->ctx->callbacks.http_error == NULL
            || conn->ctx->callbacks.http_error(conn, status)) {
                if (!conn->in_error_handler) {
                        /* Send user defined error pages, if defined */
                        error_handler = conn->ctx->config[ERROR_PAGES];
                        error_page_file_ext = conn->ctx->config[INDEX_FILES];
                        page_handler_found = 0;
                        if (error_handler != NULL) {
                                for (scope = 1; (scope <= 3) && !page_handler_found; scope++) {
                                        switch (scope) {
                                        case 1: /* Handler for specific error, e.g. 404 error */
                                                mg_snprintf(conn,
                                                            &truncated,
                                                            buf,
                                                            sizeof(buf) - 32,
                                                            "%serror%03u.",
                                                            error_handler,
                                                            status);
                                                break;
                                        case 2: /* Handler for error group, e.g., 5xx error handler
                                                 * for all server errors (500-599) */
                                                mg_snprintf(conn,
                                                            &truncated,
                                                            buf,
                                                            sizeof(buf) - 32,
                                                            "%serror%01uxx.",
                                                            error_handler,
                                                            status / 100);
                                                break;
                                        default: /* Handler for all errors */
                                                mg_snprintf(conn,
                                                            &truncated,
                                                            buf,
                                                            sizeof(buf) - 32,
                                                            "%serror.",
                                                            error_handler);
                                                break;
                                        }

                                        /* String truncation in buf may only occur if error_handler
                                         * is too long. This string is from the config, not from a
                                         * client. */
                                        (void)truncated;

                                        len = (int)strlen(buf);

                                        tstr = strchr(error_page_file_ext, '.');

                                        while (tstr) {
                                                for (i = 1; i < 32 && tstr[i] != 0 && tstr[i] != ',';
                                                     i++)
                                                        buf[len + i - 1] = tstr[i];
                                                buf[len + i - 1] = 0;
                                                if (mg_stat(conn, buf, &error_page_file)) {
                                                        page_handler_found = 1;
                                                        break;
                                                }
                                                tstr = strchr(tstr + i, '.');
                                        }
                                }
                        }

                        if (page_handler_found) {
                                conn->in_error_handler = 1;
                                handle_file_based_request(conn, buf, &error_page_file);
                                conn->in_error_handler = 0;
                                return;
                        }
                }

                /* No custom error page. Send default error page. */
                gmt_time_string(date, sizeof(date), &curtime);

                conn->must_close = 1;
                mg_printf(conn, "HTTP/1.1 %d %s\r\n", status, status_text);
                send_no_cache_header(conn);
                mg_printf(conn,
                          "Date: %s\r\n"
                          "Connection: close\r\n\r\n",
                          date);

                /* Errors 1xx, 204 and 304 MUST NOT send a body */
                if (status > 199 && status != 204 && status != 304) {

                        mg_printf(conn, "Error %d: %s\n", status, status_text);

                        if (fmt != NULL) {
                                va_start(ap, fmt);
                                mg_vsnprintf(conn, NULL, buf, sizeof(buf), fmt, ap);
                                va_end(ap);
                                mg_write(conn, buf, strlen(buf));
                                DEBUG_TRACE("Error %i - [%s]", status, buf);
                        }

                } else {
                        /* No body allowed. Close the connection. */
                        DEBUG_TRACE("Error %i", status);
                }
        }
}

#if defined(_WIN32) && !defined(__SYMBIAN32__)
/* Create substitutes for POSIX functions in Win32. */

#if defined(__MINGW32__)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif


static int
pthread_mutex_init(pthread_mutex_t *mutex, void *unused)
{
        (void)unused;
        *mutex = CreateMutex(NULL, FALSE, NULL);
        return *mutex == NULL ? -1 : 0;
}


static int
pthread_mutex_destroy(pthread_mutex_t *mutex)
{
        return CloseHandle(*mutex) == 0 ? -1 : 0;
}


static int
pthread_mutex_lock(pthread_mutex_t *mutex)
{
        return WaitForSingleObject(*mutex, INFINITE) == WAIT_OBJECT_0 ? 0 : -1;
}


#ifdef ENABLE_UNUSED_PTHREAD_FUNCTIONS
static int
pthread_mutex_trylock(pthread_mutex_t *mutex)
{
        switch (WaitForSingleObject(*mutex, 0)) {
        case WAIT_OBJECT_0:
                return 0;
        case WAIT_TIMEOUT:
                return -2; /* EBUSY */
        }
        return -1;
}
#endif


static int
pthread_mutex_unlock(pthread_mutex_t *mutex)
{
        return ReleaseMutex(*mutex) == 0 ? -1 : 0;
}


#ifndef WIN_PTHREADS_TIME_H
static int
clock_gettime(clockid_t clk_id, struct timespec *tp)
{
        FILETIME ft;
        ULARGE_INTEGER li;
        BOOL ok = FALSE;
        double d;
        static double perfcnt_per_sec = 0.0;

        if (tp) {
                memset(tp, 0, sizeof(*tp));
                if (clk_id == CLOCK_REALTIME) {
                        GetSystemTimeAsFileTime(&ft);
                        li.LowPart = ft.dwLowDateTime;
                        li.HighPart = ft.dwHighDateTime;
                        li.QuadPart -= 116444736000000000; /* 1.1.1970 in filedate */
                        tp->tv_sec = (time_t)(li.QuadPart / 10000000);
                        tp->tv_nsec = (long)(li.QuadPart % 10000000) * 100;
                        ok = TRUE;
                } else if (clk_id == CLOCK_MONOTONIC) {
                        if (perfcnt_per_sec == 0.0) {
                                QueryPerformanceFrequency((LARGE_INTEGER *)&li);
                                perfcnt_per_sec = 1.0 / li.QuadPart;
                        }
                        if (perfcnt_per_sec != 0.0) {
                                QueryPerformanceCounter((LARGE_INTEGER *)&li);
                                d = li.QuadPart * perfcnt_per_sec;
                                tp->tv_sec = (time_t)d;
                                d -= tp->tv_sec;
                                tp->tv_nsec = (long)(d * 1.0E9);
                                ok = TRUE;
                        }
                }
        }

        return ok ? 0 : -1;
}
#endif


static int
pthread_cond_init(pthread_cond_t *cv, const void *unused)
{
        (void)unused;
        InitializeCriticalSection(&cv->threadIdSec);
        cv->waitingthreadcount = 0;
        cv->waitingthreadhdls =
            (pthread_t *)mg_calloc(MAX_WORKER_THREADS, sizeof(pthread_t));
        return (cv->waitingthreadhdls != NULL) ? 0 : -1;
}


static int
pthread_cond_timedwait(pthread_cond_t *cv,
                       pthread_mutex_t *mutex,
                       const struct timespec *abstime)
{
        struct mg_workerTLS *tls =
            (struct mg_workerTLS *)pthread_getspecific(sTlsKey);
        int ok;
        struct timespec tsnow;
        int64_t nsnow, nswaitabs, nswaitrel;
        DWORD mswaitrel;

        EnterCriticalSection(&cv->threadIdSec);
        assert(cv->waitingthreadcount < MAX_WORKER_THREADS);
        cv->waitingthreadhdls[cv->waitingthreadcount] =
            tls->pthread_cond_helper_mutex;
        cv->waitingthreadcount++;
        LeaveCriticalSection(&cv->threadIdSec);

        if (abstime) {
                clock_gettime(CLOCK_REALTIME, &tsnow);
                nsnow = (((int64_t)tsnow.tv_sec) * 1000000000) + tsnow.tv_nsec;
                nswaitabs =
                    (((int64_t)abstime->tv_sec) * 1000000000) + abstime->tv_nsec;
                nswaitrel = nswaitabs - nsnow;
                if (nswaitrel < 0) {
                        nswaitrel = 0;
                }
                mswaitrel = (DWORD)(nswaitrel / 1000000);
        } else {
                mswaitrel = INFINITE;
        }

        pthread_mutex_unlock(mutex);
        ok = (WAIT_OBJECT_0
              == WaitForSingleObject(tls->pthread_cond_helper_mutex, mswaitrel));
        pthread_mutex_lock(mutex);

        return ok ? 0 : -1;
}


static int
pthread_cond_wait(pthread_cond_t *cv, pthread_mutex_t *mutex)
{
        return pthread_cond_timedwait(cv, mutex, NULL);
}


static int
pthread_cond_signal(pthread_cond_t *cv)
{
        int i;
        HANDLE wkup = NULL;
        BOOL ok = FALSE;

        EnterCriticalSection(&cv->threadIdSec);
        if (cv->waitingthreadcount) {
                wkup = cv->waitingthreadhdls[0];
                ok = SetEvent(wkup);

                for (i = 1; i < cv->waitingthreadcount; i++) {
                        cv->waitingthreadhdls[i - 1] = cv->waitingthreadhdls[i];
                }
                cv->waitingthreadcount--;

                assert(ok);
        }
        LeaveCriticalSection(&cv->threadIdSec);

        return ok ? 0 : 1;
}


static int
pthread_cond_broadcast(pthread_cond_t *cv)
{
        EnterCriticalSection(&cv->threadIdSec);
        while (cv->waitingthreadcount) {
                pthread_cond_signal(cv);
        }
        LeaveCriticalSection(&cv->threadIdSec);

        return 0;
}


static int
pthread_cond_destroy(pthread_cond_t *cv)
{
        EnterCriticalSection(&cv->threadIdSec);
        assert(cv->waitingthreadcount == 0);
        mg_free(cv->waitingthreadhdls);
        cv->waitingthreadhdls = 0;
        LeaveCriticalSection(&cv->threadIdSec);
        DeleteCriticalSection(&cv->threadIdSec);

        return 0;
}


#if defined(__MINGW32__)
/* Enable unused function warning again */
#pragma GCC diagnostic pop
#endif


/* For Windows, change all slashes to backslashes in path names. */
static void
change_slashes_to_backslashes(char *path)
{
        int i;

        for (i = 0; path[i] != '\0'; i++) {
                if (path[i] == '/') {
                        path[i] = '\\';
                }

                /* remove double backslash (check i > 0 to preserve UNC paths,
                 * like \\server\file.txt) */
                if ((path[i] == '\\') && (i > 0)) {
                        while (path[i + 1] == '\\' || path[i + 1] == '/') {
                                (void)memmove(path + i + 1, path + i + 2, strlen(path + i + 1));
                        }
                }
        }
}


static int
mg_wcscasecmp(const wchar_t *s1, const wchar_t *s2)
{
        int diff;

        do {
                diff = tolower(*s1) - tolower(*s2);
                s1++;
                s2++;
        } while (diff == 0 && s1[-1] != '\0');

        return diff;
}


/* Encode 'path' which is assumed UTF-8 string, into UNICODE string.
 * wbuf and wbuf_len is a target buffer and its length. */
static void
path_to_unicode(const struct mg_connection *conn,
                const char *path,
                wchar_t *wbuf,
                size_t wbuf_len)
{
        char buf[PATH_MAX], buf2[PATH_MAX];
        wchar_t wbuf2[MAX_PATH + 1];
        DWORD long_len, err;
        int (*fcompare)(const wchar_t *, const wchar_t *) = mg_wcscasecmp;

        mg_strlcpy(buf, path, sizeof(buf));
        change_slashes_to_backslashes(buf);

        /* Convert to Unicode and back. If doubly-converted string does not
         * match the original, something is fishy, reject. */
        memset(wbuf, 0, wbuf_len * sizeof(wchar_t));
        MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, (int)wbuf_len);
        WideCharToMultiByte(
            CP_UTF8, 0, wbuf, (int)wbuf_len, buf2, sizeof(buf2), NULL, NULL);
        if (strcmp(buf, buf2) != 0) {
                wbuf[0] = L'\0';
        }

        /* TODO: Add a configuration to switch between case sensitive and
         * case insensitive URIs for Windows server. */
        /*
        if (conn) {
            if (conn->ctx->config[WINDOWS_CASE_SENSITIVE]) {
                fcompare = wcscmp;
            }
        }
        */
        (void)conn; /* conn is currently unused */

        /* Only accept a full file path, not a Windows short (8.3) path. */
        memset(wbuf2, 0, ARRAY_SIZE(wbuf2) * sizeof(wchar_t));
        long_len = GetLongPathNameW(wbuf, wbuf2, ARRAY_SIZE(wbuf2) - 1);
        if (long_len == 0) {
                err = GetLastError();
                if (err == ERROR_FILE_NOT_FOUND) {
                        /* File does not exist. This is not always a problem here. */
                        return;
                }
        }
        if ((long_len >= ARRAY_SIZE(wbuf2)) || (fcompare(wbuf, wbuf2) != 0)) {
                /* Short name is used. */
                wbuf[0] = L'\0';
        }
}


#if defined(_WIN32_WCE)
/* Create substitutes for POSIX functions in Win32. */

#if defined(__MINGW32__)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif


static time_t
time(time_t *ptime)
{
        time_t t;
        SYSTEMTIME st;
        FILETIME ft;

        GetSystemTime(&st);
        SystemTimeToFileTime(&st, &ft);
        t = SYS2UNIX_TIME(ft.dwLowDateTime, ft.dwHighDateTime);

        if (ptime != NULL) {
                *ptime = t;
        }

        return t;
}


static struct tm *
localtime(const time_t *ptime, struct tm *ptm)
{
        int64_t t = ((int64_t)*ptime) * RATE_DIFF + EPOCH_DIFF;
        FILETIME ft, lft;
        SYSTEMTIME st;
        TIME_ZONE_INFORMATION tzinfo;

        if (ptm == NULL) {
                return NULL;
        }

        *(int64_t *)&ft = t;
        FileTimeToLocalFileTime(&ft, &lft);
        FileTimeToSystemTime(&lft, &st);
        ptm->tm_year = st.wYear - 1900;
        ptm->tm_mon = st.wMonth - 1;
        ptm->tm_wday = st.wDayOfWeek;
        ptm->tm_mday = st.wDay;
        ptm->tm_hour = st.wHour;
        ptm->tm_min = st.wMinute;
        ptm->tm_sec = st.wSecond;
        ptm->tm_yday = 0; /* hope nobody uses this */
        ptm->tm_isdst =
            GetTimeZoneInformation(&tzinfo) == TIME_ZONE_ID_DAYLIGHT ? 1 : 0;

        return ptm;
}


static struct tm *
gmtime(const time_t *ptime, struct tm *ptm)
{
        /* FIXME(lsm): fix this. */
        return localtime(ptime, ptm);
}


static size_t
strftime(char *dst, size_t dst_size, const char *fmt, const struct tm *tm)
{
        (void)mg_snprintf(NULL, dst, dst_size, "implement strftime() for WinCE");
        return 0;
}


#if defined(__MINGW32__)
/* Enable unused function warning again */
#pragma GCC diagnostic pop
#endif

#endif


/* Windows happily opens files with some garbage at the end of file name.
 * For example, fopen("a.cgi    ", "r") on Windows successfully opens
 * "a.cgi", despite one would expect an error back.
 * This function returns non-0 if path ends with some garbage. */
static int
path_cannot_disclose_cgi(const char *path)
{
        static const char *allowed_last_characters = "_-";
        int last = path[strlen(path) - 1];
        return isalnum(last) || strchr(allowed_last_characters, last) != NULL;
}


static int
mg_stat(struct mg_connection *conn, const char *path, struct file *filep)
{
        wchar_t wbuf[PATH_MAX];
        WIN32_FILE_ATTRIBUTE_DATA info;
        time_t creation_time;

        if (!filep) {
                return 0;
        }
        memset(filep, 0, sizeof(*filep));

        if (conn && is_file_in_memory(conn, path, filep)) {
                /* filep->is_directory = 0; filep->gzipped = 0; .. already done by
                 * memset */
                filep->last_modified = time(NULL);
                /* last_modified = now ... assumes the file may change during runtime,
                 * so every mg_fopen call may return different data */
                /* last_modified = conn->ctx.start_time;
                 * May be used it the data does not change during runtime. This allows
                 * browser caching. Since we do not know, we have to assume the file
                 * in memory may change. */
                return 1;
        }

        path_to_unicode(conn, path, wbuf, ARRAY_SIZE(wbuf));
        if (GetFileAttributesExW(wbuf, GetFileExInfoStandard, &info) != 0) {
                filep->size = MAKEUQUAD(info.nFileSizeLow, info.nFileSizeHigh);
                filep->last_modified =
                    SYS2UNIX_TIME(info.ftLastWriteTime.dwLowDateTime,
                                  info.ftLastWriteTime.dwHighDateTime);

                /* On Windows, the file creation time can be higher than the
                 * modification time, e.g. when a file is copied.
                 * Since the Last-Modified timestamp is used for caching
                 * it should be based on the most recent timestamp. */
                creation_time = SYS2UNIX_TIME(info.ftCreationTime.dwLowDateTime,
                                              info.ftCreationTime.dwHighDateTime);
                if (creation_time > filep->last_modified) {
                        filep->last_modified = creation_time;
                }

                filep->is_directory = info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;
                /* If file name is fishy, reset the file structure and return
                 * error.
                 * Note it is important to reset, not just return the error, cause
                 * functions like is_file_opened() check the struct. */
                if (!filep->is_directory && !path_cannot_disclose_cgi(path)) {
                        memset(filep, 0, sizeof(*filep));
                        return 0;
                }

                return 1;
        }

        return 0;
}


static int
mg_remove(const struct mg_connection *conn, const char *path)
{
        wchar_t wbuf[PATH_MAX];
        path_to_unicode(conn, path, wbuf, ARRAY_SIZE(wbuf));
        return DeleteFileW(wbuf) ? 0 : -1;
}


static int
mg_mkdir(const struct mg_connection *conn, const char *path, int mode)
{
        wchar_t wbuf[PATH_MAX];
        (void)mode;
        path_to_unicode(conn, path, wbuf, ARRAY_SIZE(wbuf));
        return CreateDirectoryW(wbuf, NULL) ? 0 : -1;
}


/* Create substitutes for POSIX functions in Win32. */

#if defined(__MINGW32__)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif


/* Implementation of POSIX opendir/closedir/readdir for Windows. */
static DIR *
mg_opendir(const struct mg_connection *conn, const char *name)
{
        DIR *dir = NULL;
        wchar_t wpath[PATH_MAX];
        DWORD attrs;

        if (name == NULL) {
                SetLastError(ERROR_BAD_ARGUMENTS);
        } else if ((dir = (DIR *)mg_malloc(sizeof(*dir))) == NULL) {
                SetLastError(ERROR_NOT_ENOUGH_MEMORY);
        } else {
                path_to_unicode(conn, name, wpath, ARRAY_SIZE(wpath));
                attrs = GetFileAttributesW(wpath);
                if (attrs != 0xFFFFFFFF && ((attrs & FILE_ATTRIBUTE_DIRECTORY)
                                            == FILE_ATTRIBUTE_DIRECTORY)) {
                        (void)wcscat(wpath, L"\\*");
                        dir->handle = FindFirstFileW(wpath, &dir->info);
                        dir->result.d_name[0] = '\0';
                } else {
                        mg_free(dir);
                        dir = NULL;
                }
        }

        return dir;
}


static int
mg_closedir(DIR *dir)
{
        int result = 0;

        if (dir != NULL) {
                if (dir->handle != INVALID_HANDLE_VALUE)
                        result = FindClose(dir->handle) ? 0 : -1;

                mg_free(dir);
        } else {
                result = -1;
                SetLastError(ERROR_BAD_ARGUMENTS);
        }

        return result;
}


static struct dirent *
mg_readdir(DIR *dir)
{
        struct dirent *result = 0;

        if (dir) {
                if (dir->handle != INVALID_HANDLE_VALUE) {
                        result = &dir->result;
                        (void)WideCharToMultiByte(CP_UTF8,
                                                  0,
                                                  dir->info.cFileName,
                                                  -1,
                                                  result->d_name,
                                                  sizeof(result->d_name),
                                                  NULL,
                                                  NULL);

                        if (!FindNextFileW(dir->handle, &dir->info)) {
                                (void)FindClose(dir->handle);
                                dir->handle = INVALID_HANDLE_VALUE;
                        }

                } else {
                        SetLastError(ERROR_FILE_NOT_FOUND);
                }
        } else {
                SetLastError(ERROR_BAD_ARGUMENTS);
        }

        return result;
}


#ifndef HAVE_POLL
static int
poll(struct pollfd *pfd, unsigned int n, int milliseconds)
{
        struct timeval tv;
        fd_set set;
        unsigned int i;
        int result;
        SOCKET maxfd = 0;

        memset(&tv, 0, sizeof(tv));
        tv.tv_sec = milliseconds / 1000;
        tv.tv_usec = (milliseconds % 1000) * 1000;
        FD_ZERO(&set);

        for (i = 0; i < n; i++) {
                FD_SET((SOCKET)pfd[i].fd, &set);
                pfd[i].revents = 0;

                if (pfd[i].fd > maxfd) {
                        maxfd = pfd[i].fd;
                }
        }

        if ((result = select((int)maxfd + 1, &set, NULL, NULL, &tv)) > 0) {
                for (i = 0; i < n; i++) {
                        if (FD_ISSET(pfd[i].fd, &set)) {
                                pfd[i].revents = POLLIN;
                        }
                }
        }

        return result;
}
#endif /* HAVE_POLL */

#if defined(__MINGW32__)
/* Enable unused function warning again */
#pragma GCC diagnostic pop
#endif


static void
set_close_on_exec(SOCKET sock, struct mg_connection *conn /* may be null */)
{
        (void)conn; /* Unused. */
        (void)SetHandleInformation((HANDLE)(intptr_t)sock, HANDLE_FLAG_INHERIT, 0);
}


int
mg_start_thread(mg_thread_func_t f, void *p)
{
#if defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1)
        /* Compile-time option to control stack size, e.g. -DUSE_STACK_SIZE=16384
         */
        return ((_beginthread((void(__cdecl *)(void *))f, USE_STACK_SIZE, p)
                 == ((uintptr_t)(-1L)))
                    ? -1
                    : 0);
#else
        return (
            (_beginthread((void(__cdecl *)(void *))f, 0, p) == ((uintptr_t)(-1L)))
                ? -1
                : 0);
#endif /* defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1) */
}


/* Start a thread storing the thread context. */
static int
mg_start_thread_with_id(unsigned(__stdcall *f)(void *),
                        void *p,
                        pthread_t *threadidptr)
{
        uintptr_t uip;
        HANDLE threadhandle;
        int result = -1;

        uip = _beginthreadex(NULL, 0, (unsigned(__stdcall *)(void *))f, p, 0, NULL);
        threadhandle = (HANDLE)uip;
        if ((uip != (uintptr_t)(-1L)) && (threadidptr != NULL)) {
                *threadidptr = threadhandle;
                result = 0;
        }

        return result;
}


/* Wait for a thread to finish. */
static int
mg_join_thread(pthread_t threadid)
{
        int result;
        DWORD dwevent;

        result = -1;
        dwevent = WaitForSingleObject(threadid, INFINITE);
        if (dwevent == WAIT_FAILED) {
                DEBUG_TRACE("WaitForSingleObject() failed, error %d", ERRNO);
        } else {
                if (dwevent == WAIT_OBJECT_0) {
                        CloseHandle(threadid);
                        result = 0;
                }
        }

        return result;
}

#if !defined(NO_SSL_DL)
/* Create substitutes for POSIX functions in Win32. */

#if defined(__MINGW32__)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif


static HANDLE
dlopen(const char *dll_name, int flags)
{
        wchar_t wbuf[PATH_MAX];
        (void)flags;
        path_to_unicode(NULL, dll_name, wbuf, ARRAY_SIZE(wbuf));
        return LoadLibraryW(wbuf);
}


static int
dlclose(void *handle)
{
        int result;

        if (FreeLibrary((HMODULE)handle) != 0) {
                result = 0;
        } else {
                result = -1;
        }

        return result;
}


#if defined(__MINGW32__)
/* Enable unused function warning again */
#pragma GCC diagnostic pop
#endif

#endif


#if !defined(NO_CGI)
#define SIGKILL (0)

static int
kill(pid_t pid, int sig_num)
{
        (void)TerminateProcess((HANDLE)pid, (UINT)sig_num);
        (void)CloseHandle((HANDLE)pid);
        return 0;
}


static void
trim_trailing_whitespaces(char *s)
{
        char *e = s + strlen(s) - 1;
        while (e > s && isspace(*(unsigned char *)e)) {
                *e-- = '\0';
        }
}


static pid_t
spawn_process(struct mg_connection *conn,
              const char *prog,
              char *envblk,
              char *envp[],
              int fdin[2],
              int fdout[2],
              int fderr[2],
              const char *dir)
{
        HANDLE me;
        char *p, *interp, full_interp[PATH_MAX], full_dir[PATH_MAX],
            cmdline[PATH_MAX], buf[PATH_MAX];
        int truncated;
        struct file file = STRUCT_FILE_INITIALIZER;
        STARTUPINFOA si;
        PROCESS_INFORMATION pi = {0};

        (void)envp;

        memset(&si, 0, sizeof(si));
        si.cb = sizeof(si);

        si.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
        si.wShowWindow = SW_HIDE;

        me = GetCurrentProcess();
        DuplicateHandle(me,
                        (HANDLE)_get_osfhandle(fdin[0]),
                        me,
                        &si.hStdInput,
                        0,
                        TRUE,
                        DUPLICATE_SAME_ACCESS);
        DuplicateHandle(me,
                        (HANDLE)_get_osfhandle(fdout[1]),
                        me,
                        &si.hStdOutput,
                        0,
                        TRUE,
                        DUPLICATE_SAME_ACCESS);
        DuplicateHandle(me,
                        (HANDLE)_get_osfhandle(fderr[1]),
                        me,
                        &si.hStdError,
                        0,
                        TRUE,
                        DUPLICATE_SAME_ACCESS);

        /* Mark handles that should not be inherited. See
         * https://msdn.microsoft.com/en-us/library/windows/desktop/ms682499%28v=vs.85%29.aspx
         */
        SetHandleInformation((HANDLE)_get_osfhandle(fdin[1]),
                             HANDLE_FLAG_INHERIT,
                             0);
        SetHandleInformation((HANDLE)_get_osfhandle(fdout[0]),
                             HANDLE_FLAG_INHERIT,
                             0);
        SetHandleInformation((HANDLE)_get_osfhandle(fderr[0]),
                             HANDLE_FLAG_INHERIT,
                             0);

        /* If CGI file is a script, try to read the interpreter line */
        interp = conn->ctx->config[CGI_INTERPRETER];
        if (interp == NULL) {
                buf[0] = buf[1] = '\0';

                /* Read the first line of the script into the buffer */
                mg_snprintf(
                    conn, &truncated, cmdline, sizeof(cmdline), "%s/%s", dir, prog);

                if (truncated) {
                        pi.hProcess = (pid_t)-1;
                        goto spawn_cleanup;
                }

                if (mg_fopen(conn, cmdline, "r", &file)) {
                        p = (char *)file.membuf;
                        mg_fgets(buf, sizeof(buf), &file, &p);
                        mg_fclose(&file);
                        buf[sizeof(buf) - 1] = '\0';
                }

                if (buf[0] == '#' && buf[1] == '!') {
                        trim_trailing_whitespaces(buf + 2);
                } else {
                        buf[2] = '\0';
                }
                interp = buf + 2;
        }

        if (interp[0] != '\0') {
                GetFullPathNameA(interp, sizeof(full_interp), full_interp, NULL);
                interp = full_interp;
        }
        GetFullPathNameA(dir, sizeof(full_dir), full_dir, NULL);

        if (interp[0] != '\0') {
                mg_snprintf(conn,
                            &truncated,
                            cmdline,
                            sizeof(cmdline),
                            "\"%s\" \"%s\\%s\"",
                            interp,
                            full_dir,
                            prog);
        } else {
                mg_snprintf(conn,
                            &truncated,
                            cmdline,
                            sizeof(cmdline),
                            "\"%s\\%s\"",
                            full_dir,
                            prog);
        }

        if (truncated) {
                pi.hProcess = (pid_t)-1;
                goto spawn_cleanup;
        }

        DEBUG_TRACE("Running [%s]", cmdline);
        if (CreateProcessA(NULL,
                           cmdline,
                           NULL,
                           NULL,
                           TRUE,
                           CREATE_NEW_PROCESS_GROUP,
                           envblk,
                           NULL,
                           &si,
                           &pi) == 0) {
                mg_cry(
                    conn, "%s: CreateProcess(%s): %ld", __func__, cmdline, (long)ERRNO);
                pi.hProcess = (pid_t)-1;
                /* goto spawn_cleanup; */
        }

spawn_cleanup:
        (void)CloseHandle(si.hStdOutput);
        (void)CloseHandle(si.hStdError);
        (void)CloseHandle(si.hStdInput);
        if (pi.hThread != NULL) {
                (void)CloseHandle(pi.hThread);
        }

        return (pid_t)pi.hProcess;
}
#endif /* !NO_CGI */


static int
set_non_blocking_mode(SOCKET sock)
{
        unsigned long on = 1;
        return ioctlsocket(sock, (long)FIONBIO, &on);
}

#else

static int
mg_stat(struct mg_connection *conn, const char *path, struct file *filep)
{
        struct stat st;
        if (!filep) {
                return 0;
        }
        memset(filep, 0, sizeof(*filep));

        if (conn && is_file_in_memory(conn, path, filep)) {
                return 1;
        }

        if (0 == stat(path, &st)) {
                filep->size = (uint64_t)(st.st_size);
                filep->last_modified = st.st_mtime;
                filep->is_directory = S_ISDIR(st.st_mode);
                return 1;
        }

        return 0;
}


static void
set_close_on_exec(SOCKET fd, struct mg_connection *conn /* may be null */)
{
        if (fcntl(fd, F_SETFD, FD_CLOEXEC) != 0) {
                if (conn) {
                        mg_cry(conn,
                               "%s: fcntl(F_SETFD FD_CLOEXEC) failed: %s",
                               __func__,
                               strerror(ERRNO));
                }
        }
}


int
mg_start_thread(mg_thread_func_t func, void *param)
{
        pthread_t thread_id;
        pthread_attr_t attr;
        int result;

        (void)pthread_attr_init(&attr);
        (void)pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

#if defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1)
        /* Compile-time option to control stack size,
         * e.g. -DUSE_STACK_SIZE=16384 */
        (void)pthread_attr_setstacksize(&attr, USE_STACK_SIZE);
#endif /* defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1) */

        result = pthread_create(&thread_id, &attr, func, param);
        pthread_attr_destroy(&attr);

        return result;
}


/* Start a thread storing the thread context. */
static int
mg_start_thread_with_id(mg_thread_func_t func,
                        void *param,
                        pthread_t *threadidptr)
{
        pthread_t thread_id;
        pthread_attr_t attr;
        int result;

        (void)pthread_attr_init(&attr);

#if defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1)
        /* Compile-time option to control stack size,
         * e.g. -DUSE_STACK_SIZE=16384 */
        (void)pthread_attr_setstacksize(&attr, USE_STACK_SIZE);
#endif /* defined(USE_STACK_SIZE) && USE_STACK_SIZE > 1 */

        result = pthread_create(&thread_id, &attr, func, param);
        pthread_attr_destroy(&attr);
        if ((result == 0) && (threadidptr != NULL)) {
                *threadidptr = thread_id;
        }
        return result;
}


/* Wait for a thread to finish. */
static int
mg_join_thread(pthread_t threadid)
{
        int result;

        result = pthread_join(threadid, NULL);
        return result;
}


#ifndef NO_CGI
static pid_t
spawn_process(struct mg_connection *conn,
              const char *prog,
              char *envblk,
              char *envp[],
              int fdin[2],
              int fdout[2],
              int fderr[2],
              const char *dir)
{
        pid_t pid;
        const char *interp;

        (void)envblk;

        if (conn == NULL) {
                return 0;
        }

        if ((pid = fork()) == -1) {
                /* Parent */
                send_http_error(conn,
                                500,
                                "Error: Creating CGI process\nfork(): %s",
                                strerror(ERRNO));
        } else if (pid == 0) {
                /* Child */
                if (chdir(dir) != 0) {
                        mg_cry(conn, "%s: chdir(%s): %s", __func__, dir, strerror(ERRNO));
                } else if (dup2(fdin[0], 0) == -1) {
                        mg_cry(conn,
                               "%s: dup2(%d, 0): %s",
                               __func__,
                               fdin[0],
                               strerror(ERRNO));
                } else if (dup2(fdout[1], 1) == -1) {
                        mg_cry(conn,
                               "%s: dup2(%d, 1): %s",
                               __func__,
                               fdout[1],
                               strerror(ERRNO));
                } else if (dup2(fderr[1], 2) == -1) {
                        mg_cry(conn,
                               "%s: dup2(%d, 2): %s",
                               __func__,
                               fderr[1],
                               strerror(ERRNO));
                } else {
                        /* Keep stderr and stdout in two different pipes.
                         * Stdout will be sent back to the client,
                         * stderr should go into a server error log. */
                        (void)close(fdin[0]);
                        (void)close(fdout[1]);
                        (void)close(fderr[1]);

                        /* Close write end fdin and read end fdout and fderr */
                        (void)close(fdin[1]);
                        (void)close(fdout[0]);
                        (void)close(fderr[0]);

                        /* After exec, all signal handlers are restored to their default
                         * values, with one exception of SIGCHLD. According to
                         * POSIX.1-2001 and Linux's implementation, SIGCHLD's handler will
                         * leave unchanged after exec if it was set to be ignored. Restore
                         * it to default action. */
                        signal(SIGCHLD, SIG_DFL);

                        interp = conn->ctx->config[CGI_INTERPRETER];
                        if (interp == NULL) {
                                (void)execle(prog, prog, NULL, envp);
                                mg_cry(conn,
                                       "%s: execle(%s): %s",
                                       __func__,
                                       prog,
                                       strerror(ERRNO));
                        } else {
                                (void)execle(interp, interp, prog, NULL, envp);
                                mg_cry(conn,
                                       "%s: execle(%s %s): %s",
                                       __func__,
                                       interp,
                                       prog,
                                       strerror(ERRNO));
                        }
                }
                exit(EXIT_FAILURE);
        }

        return pid;
}
#endif /* !NO_CGI */


static int
set_non_blocking_mode(SOCKET sock)
{
        int flags;

        flags = fcntl(sock, F_GETFL, 0);
        (void)fcntl(sock, F_SETFL, flags | O_NONBLOCK);

        return 0;
}
#endif /* _WIN32 */
/* End of initial operating system specific define block. */


/* Get a random number (independent of C rand function) */
static uint64_t
get_random(void)
{
        static uint64_t lfsr = 0; /* Linear feedback shift register */
        static uint64_t lcg = 0;  /* Linear congruential generator */
        struct timespec now;

        memset(&now, 0, sizeof(now));
        clock_gettime(CLOCK_MONOTONIC, &now);

        if (lfsr == 0) {
                /* lfsr will be only 0 if has not been initialized,
                 * so this code is called only once. */
                lfsr = (((uint64_t)now.tv_sec) << 21) ^ ((uint64_t)now.tv_nsec)
                       ^ ((uint64_t)(ptrdiff_t)&now) ^ (((uint64_t)time(NULL)) << 33);
                lcg = (((uint64_t)now.tv_sec) << 25) + (uint64_t)now.tv_nsec
                      + (uint64_t)(ptrdiff_t)&now;
        } else {
                /* Get the next step of both random number generators. */
                lfsr = (lfsr >> 1)
                       | ((((lfsr >> 0) ^ (lfsr >> 1) ^ (lfsr >> 3) ^ (lfsr >> 4)) & 1)
                          << 63);
                lcg = lcg * 6364136223846793005 + 1442695040888963407;
        }

        /* Combining two pseudo-random number generators and a high resolution part
         * of the current server time will make it hard (impossible?) to guess the
         * next number. */
        return (lfsr ^ lcg ^ (uint64_t)now.tv_nsec);
}


/* Write data to the IO channel - opened file descriptor, socket or SSL
 * descriptor. Return number of bytes written. */
static int
push(struct mg_context *ctx,
     FILE *fp,
     SOCKET sock,
     SSL *ssl,
     const char *buf,
     int len,
     double timeout)
{
        struct timespec start, now;
        int n, err;

#ifdef _WIN32
        typedef int len_t;
#else
        typedef size_t len_t;
#endif

        if (timeout > 0) {
                memset(&start, 0, sizeof(start));
                memset(&now, 0, sizeof(now));
                clock_gettime(CLOCK_MONOTONIC, &start);
        }

        if (ctx == NULL) {
                return -1;
        }

#ifdef NO_SSL
        if (ssl) {
                return -1;
        }
#endif

        do {

#ifndef NO_SSL
                if (ssl != NULL) {
                        n = SSL_write(ssl, buf, len);
                        if (n <= 0) {
                                err = SSL_get_error(ssl, n);
                                if ((err == 5 /* SSL_ERROR_SYSCALL */) && (n == -1)) {
                                        err = ERRNO;
                                } else {
                                        DEBUG_TRACE("SSL_write() failed, error %d", err);
                                        return -1;
                                }
                        } else {
                                err = 0;
                        }
                } else
#endif
                    if (fp != NULL) {
                        n = (int)fwrite(buf, 1, (size_t)len, fp);
                        if (ferror(fp)) {
                                n = -1;
                                err = ERRNO;
                        } else {
                                err = 0;
                        }
                } else {
                        n = (int)send(sock, buf, (len_t)len, MSG_NOSIGNAL);
                        err = (n < 0) ? ERRNO : 0;
                }

                if (ctx->stop_flag) {
                        return -1;
                }

                if ((n > 0) || (n == 0 && len == 0)) {
                        /* some data has been read, or no data was requested */
                        return n;
                }
                if (n == 0) {
                        /* shutdown of the socket at client side */
                        return -1;
                }
                if (n < 0) {
                        /* socket error - check errno */
                        DEBUG_TRACE("send() failed, error %d", err);

                        /* TODO: error handling depending on the error code.
                         * These codes are different between Windows and Linux.
                         */
                        return -1;
                }

                /* This code is not reached in the moment.
                 * ==> Fix the TODOs above first. */

                if (timeout > 0) {
                        clock_gettime(CLOCK_MONOTONIC, &now);
                }

        } while ((timeout <= 0) || (mg_difftimespec(&now, &start) <= timeout));

        (void)err; /* Avoid unused warning if NO_SSL is set and DEBUG_TRACE is not
                      used */

        return -1;
}


static int64_t
push_all(struct mg_context *ctx,
         FILE *fp,
         SOCKET sock,
         SSL *ssl,
         const char *buf,
         int64_t len)
{
        double timeout = -1.0;
        int64_t n, nwritten = 0;

        if (ctx == NULL) {
                return -1;
        }

        if (ctx->config[REQUEST_TIMEOUT]) {
                timeout = atoi(ctx->config[REQUEST_TIMEOUT]) / 1000.0;
        }

        while (len > 0 && ctx->stop_flag == 0) {
                n = push(ctx, fp, sock, ssl, buf + nwritten, (int)len, timeout);
                if (n < 0) {
                        if (nwritten == 0) {
                                nwritten = n; /* Propagate the error */
                        }
                        break;
                } else if (n == 0) {
                        break; /* No more data to write */
                } else {
                        nwritten += n;
                        len -= n;
                }
        }

        return nwritten;
}


/* Read from IO channel - opened file descriptor, socket, or SSL descriptor.
 * Return negative value on error, or number of bytes read on success. */
static int
pull(FILE *fp, struct mg_connection *conn, char *buf, int len, double timeout)
{
        int nread, err;
        struct timespec start, now;

#ifdef _WIN32
        typedef int len_t;
#else
        typedef size_t len_t;
#endif

        if (timeout > 0) {
                memset(&start, 0, sizeof(start));
                memset(&now, 0, sizeof(now));
                clock_gettime(CLOCK_MONOTONIC, &start);
        }

        do {
                if (fp != NULL) {
                        /* Use read() instead of fread(), because if we're reading from the
                         * CGI pipe, fread() may block until IO buffer is filled up. We
                         * cannot afford to block and must pass all read bytes immediately
                         * to the client. */
                        nread = (int)read(fileno(fp), buf, (size_t)len);
                        err = (nread < 0) ? ERRNO : 0;

#ifndef NO_SSL
                } else if (conn->ssl != NULL) {
                        nread = SSL_read(conn->ssl, buf, len);
                        if (nread <= 0) {
                                err = SSL_get_error(conn->ssl, nread);
                                if ((err == 5 /* SSL_ERROR_SYSCALL */) && (nread == -1)) {
                                        err = ERRNO;
                                } else {
                                        DEBUG_TRACE("SSL_read() failed, error %d", err);
                                        return -1;
                                }
                        } else {
                                err = 0;
                        }
#endif

                } else {
                        nread = (int)recv(conn->client.sock, buf, (len_t)len, 0);
                        err = (nread < 0) ? ERRNO : 0;
                }

                if (conn->ctx->stop_flag) {
                        return -1;
                }

                if ((nread > 0) || (nread == 0 && len == 0)) {
                        /* some data has been read, or no data was requested */
                        return nread;
                }
                if (nread == 0) {
                        /* shutdown of the socket at client side */
                        return -1;
                }
                if (nread < 0) {
/* socket error - check errno */
#ifdef _WIN32
                        if (err == WSAEWOULDBLOCK) {
                                /* standard case if called from close_socket_gracefully */
                                return -1;
                        } else if (err == WSAETIMEDOUT) {
                                /* timeout is handled by the while loop  */
                        } else {
                                DEBUG_TRACE("recv() failed, error %d", err);
                                return -1;
                        }
#else
                        /* TODO: POSIX returns either EAGAIN or EWOULDBLOCK in both cases,
                         * if the timeout is reached and if the socket was set to non-
                         * blocking in close_socket_gracefully, so we can not distinguish
                         * here. We have to wait for the timeout in both cases for now.
                         */
                        if (err == EAGAIN || err == EWOULDBLOCK || err == EINTR) {
                                /* EAGAIN/EWOULDBLOCK:
                                 * standard case if called from close_socket_gracefully
                                 * => should return -1 */
                                /* or timeout occured
                                 * => the code must stay in the while loop */

                                /* EINTR can be generated on a socket with a timeout set even
                                 * when SA_RESTART is effective for all relevant signals
                                 * (see signal(7)).
                                 * => stay in the while loop */
                        } else {
                                DEBUG_TRACE("recv() failed, error %d", err);
                                return -1;
                        }
#endif
                }
                if (timeout > 0) {
                        clock_gettime(CLOCK_MONOTONIC, &now);
                }
        } while ((timeout <= 0) || (mg_difftimespec(&now, &start) <= timeout));

        /* Timeout occured, but no data available. */
        return -1;
}


static int
pull_all(FILE *fp, struct mg_connection *conn, char *buf, int len)
{
        int n, nread = 0;
        double timeout = -1.0;

        if (conn->ctx->config[REQUEST_TIMEOUT]) {
                timeout = atoi(conn->ctx->config[REQUEST_TIMEOUT]) / 1000.0;
        }

        while (len > 0 && conn->ctx->stop_flag == 0) {
                n = pull(fp, conn, buf + nread, len, timeout);
                if (n < 0) {
                        if (nread == 0) {
                                nread = n; /* Propagate the error */
                        }
                        break;
                } else if (n == 0) {
                        break; /* No more data to read */
                } else {
                        conn->consumed_content += n;
                        nread += n;
                        len -= n;
                }
        }

        return nread;
}


static void
discard_unread_request_data(struct mg_connection *conn)
{
        char buf[MG_BUF_LEN];
        size_t to_read;
        int nread;

        if (conn == NULL) {
                return;
        }

        to_read = sizeof(buf);

        if (conn->is_chunked) {
                /* Chunked encoding: 1=chunk not read completely, 2=chunk read
                 * completely */
                while (conn->is_chunked == 1) {
                        nread = mg_read(conn, buf, to_read);
                        if (nread <= 0) {
                                break;
                        }
                }

        } else {
                /* Not chunked: content length is known */
                while (conn->consumed_content < conn->content_len) {
                        if (to_read
                            > (size_t)(conn->content_len - conn->consumed_content)) {
                                to_read = (size_t)(conn->content_len - conn->consumed_content);
                        }

                        nread = mg_read(conn, buf, to_read);
                        if (nread <= 0) {
                                break;
                        }
                }
        }
}


static int
mg_read_inner(struct mg_connection *conn, void *buf, size_t len)
{
        int64_t n, buffered_len, nread;
        int64_t len64 =
            (int64_t)(len > INT_MAX ? INT_MAX : len); /* since the return value is
                                                       * int, we may not read more
                                                       * bytes */
        const char *body;

        if (conn == NULL) {
                return 0;
        }

        /* If Content-Length is not set for a PUT or POST request, read until
         * socket is closed */
        if (conn->consumed_content == 0 && conn->content_len == -1) {
                conn->content_len = INT64_MAX;
                conn->must_close = 1;
        }

        nread = 0;
        if (conn->consumed_content < conn->content_len) {
                /* Adjust number of bytes to read. */
                int64_t left_to_read = conn->content_len - conn->consumed_content;
                if (left_to_read < len64) {
                        /* Do not read more than the total content length of the request.
                         */
                        len64 = left_to_read;
                }

                /* Return buffered data */
                buffered_len = (int64_t)(conn->data_len) - (int64_t)conn->request_len
                               - conn->consumed_content;
                if (buffered_len > 0) {
                        if (len64 < buffered_len) {
                                buffered_len = len64;
                        }
                        body = conn->buf + conn->request_len + conn->consumed_content;
                        memcpy(buf, body, (size_t)buffered_len);
                        len64 -= buffered_len;
                        conn->consumed_content += buffered_len;
                        nread += buffered_len;
                        buf = (char *)buf + buffered_len;
                }

                /* We have returned all buffered data. Read new data from the remote
                 * socket.
                 */
                if ((n = pull_all(NULL, conn, (char *)buf, (int)len64)) >= 0) {
                        nread += n;
                } else {
                        nread = (nread > 0 ? nread : n);
                }
        }
        return (int)nread;
}


static char
mg_getc(struct mg_connection *conn)
{
        char c;
        if (conn == NULL) {
                return 0;
        }
        conn->content_len++;
        if (mg_read_inner(conn, &c, 1) <= 0) {
                return (char)0;
        }
        return c;
}


int
mg_read(struct mg_connection *conn, void *buf, size_t len)
{
        if (len > INT_MAX) {
                len = INT_MAX;
        }

        if (conn == NULL) {
                return 0;
        }

        if (conn->is_chunked) {
                size_t all_read = 0;

                while (len > 0) {

                        if (conn->is_chunked == 2) {
                                /* No more data left to read */
                                return 0;
                        }

                        if (conn->chunk_remainder) {
                                /* copy from the remainder of the last received chunk */
                                long read_ret;
                                size_t read_now =
                                    ((conn->chunk_remainder > len) ? (len)
                                                                   : (conn->chunk_remainder));

                                conn->content_len += (int)read_now;
                                read_ret =
                                    mg_read_inner(conn, (char *)buf + all_read, read_now);
                                all_read += (size_t)read_ret;

                                conn->chunk_remainder -= read_now;
                                len -= read_now;

                                if (conn->chunk_remainder == 0) {
                                        /* the rest of the data in the current chunk has been read
                                         */
                                        if ((mg_getc(conn) != '\r') || (mg_getc(conn) != '\n')) {
                                                /* Protocol violation */
                                                return -1;
                                        }
                                }

                        } else {
                                /* fetch a new chunk */
                                int i = 0;
                                char lenbuf[64];
                                char *end = 0;
                                unsigned long chunkSize = 0;

                                for (i = 0; i < ((int)sizeof(lenbuf) - 1); i++) {
                                        lenbuf[i] = mg_getc(conn);
                                        if (i > 0 && lenbuf[i] == '\r' && lenbuf[i - 1] != '\r') {
                                                continue;
                                        }
                                        if (i > 1 && lenbuf[i] == '\n' && lenbuf[i - 1] == '\r') {
                                                lenbuf[i + 1] = 0;
                                                chunkSize = strtoul(lenbuf, &end, 16);
                                                if (chunkSize == 0) {
                                                        /* regular end of content */
                                                        conn->is_chunked = 2;
                                                }
                                                break;
                                        }
                                        if (!isalnum(lenbuf[i])) {
                                                /* illegal character for chunk length */
                                                return -1;
                                        }
                                }
                                if ((end == NULL) || (*end != '\r')) {
                                        /* chunksize not set correctly */
                                        return -1;
                                }
                                if (chunkSize == 0) {
                                        break;
                                }

                                conn->chunk_remainder = chunkSize;
                        }
                }

                return (int)all_read;
        }
        return mg_read_inner(conn, buf, len);
}


int
mg_write(struct mg_connection *conn, const void *buf, size_t len)
{
        time_t now;
        int64_t n, total, allowed;

        if (conn == NULL) {
                return 0;
        }

        if (conn->throttle > 0) {
                if ((now = time(NULL)) != conn->last_throttle_time) {
                        conn->last_throttle_time = now;
                        conn->last_throttle_bytes = 0;
                }
                allowed = conn->throttle - conn->last_throttle_bytes;
                if (allowed > (int64_t)len) {
                        allowed = (int64_t)len;
                }
                if ((total = push_all(conn->ctx,
                                      NULL,
                                      conn->client.sock,
                                      conn->ssl,
                                      (const char *)buf,
                                      (int64_t)allowed)) == allowed) {
                        buf = (const char *)buf + total;
                        conn->last_throttle_bytes += total;
                        while (total < (int64_t)len && conn->ctx->stop_flag == 0) {
                                allowed = conn->throttle > (int64_t)len - total
                                              ? (int64_t)len - total
                                              : conn->throttle;
                                if ((n = push_all(conn->ctx,
                                                  NULL,
                                                  conn->client.sock,
                                                  conn->ssl,
                                                  (const char *)buf,
                                                  (int64_t)allowed)) != allowed) {
                                        break;
                                }
                                sleep(1);
                                conn->last_throttle_bytes = allowed;
                                conn->last_throttle_time = time(NULL);
                                buf = (const char *)buf + n;
                                total += n;
                        }
                }
        } else {
                total = push_all(conn->ctx,
                                 NULL,
                                 conn->client.sock,
                                 conn->ssl,
                                 (const char *)buf,
                                 (int64_t)len);
        }
        return (int)total;
}


/* Alternative alloc_vprintf() for non-compliant C runtimes */
static int
alloc_vprintf2(char **buf, const char *fmt, va_list ap)
{
        va_list ap_copy;
        size_t size = MG_BUF_LEN / 4;
        int len = -1;

        *buf = NULL;
        while (len < 0) {
                if (*buf) {
                        mg_free(*buf);
                }

                size *= 4;
                *buf = (char *)mg_malloc(size);
                if (!*buf) {
                        break;
                }

                va_copy(ap_copy, ap);
                len = vsnprintf_impl(*buf, size - 1, fmt, ap_copy);
                va_end(ap_copy);
                (*buf)[size - 1] = 0;
        }

        return len;
}


/* Print message to buffer. If buffer is large enough to hold the message,
 * return buffer. If buffer is to small, allocate large enough buffer on heap,
 * and return allocated buffer. */
static int
alloc_vprintf(char **out_buf,
              char *prealloc_buf,
              size_t prealloc_size,
              const char *fmt,
              va_list ap)
{
        va_list ap_copy;
        int len;

        /* Windows is not standard-compliant, and vsnprintf() returns -1 if
         * buffer is too small. Also, older versions of msvcrt.dll do not have
         * _vscprintf().  However, if size is 0, vsnprintf() behaves correctly.
         * Therefore, we make two passes: on first pass, get required message
         * length.
         * On second pass, actually print the message. */
        va_copy(ap_copy, ap);
        len = vsnprintf_impl(NULL, 0, fmt, ap_copy);
        va_end(ap_copy);

        if (len < 0) {
                /* C runtime is not standard compliant, vsnprintf() returned -1.
                 * Switch to alternative code path that uses incremental allocations.
                */
                va_copy(ap_copy, ap);
                len = alloc_vprintf2(out_buf, fmt, ap);
                va_end(ap_copy);

        } else if ((size_t)(len) >= prealloc_size) {
                /* The pre-allocated buffer not large enough. */
                /* Allocate a new buffer. */
                *out_buf = (char *)mg_malloc((size_t)(len) + 1);
                if (!*out_buf) {
                        /* Allocation failed. Return -1 as "out of memory" error. */
                        return -1;
                }
                /* Buffer allocation successful. Store the string there. */
                va_copy(ap_copy, ap);
                IGNORE_UNUSED_RESULT(
                    vsnprintf_impl(*out_buf, (size_t)(len) + 1, fmt, ap_copy));
                va_end(ap_copy);

        } else {
                /* The pre-allocated buffer is large enough.
                 * Use it to store the string and return the address. */
                va_copy(ap_copy, ap);
                IGNORE_UNUSED_RESULT(
                    vsnprintf_impl(prealloc_buf, prealloc_size, fmt, ap_copy));
                va_end(ap_copy);
                *out_buf = prealloc_buf;
        }

        return len;
}


static int
mg_vprintf(struct mg_connection *conn, const char *fmt, va_list ap)
{
        char mem[MG_BUF_LEN];
        char *buf = NULL;
        int len;

        if ((len = alloc_vprintf(&buf, mem, sizeof(mem), fmt, ap)) > 0) {
                len = mg_write(conn, buf, (size_t)len);
        }
        if (buf != mem && buf != NULL) {
                mg_free(buf);
        }

        return len;
}


int
mg_printf(struct mg_connection *conn, const char *fmt, ...)
{
        va_list ap;
        int result;

        va_start(ap, fmt);
        result = mg_vprintf(conn, fmt, ap);
        va_end(ap);

        return result;
}


int
mg_url_decode(const char *src,
              int src_len,
              char *dst,
              int dst_len,
              int is_form_url_encoded)
{
        int i, j, a, b;
#define HEXTOI(x) (isdigit(x) ? x - '0' : x - 'W')

        for (i = j = 0; i < src_len && j < dst_len - 1; i++, j++) {
                if (i < src_len - 2 && src[i] == '%'
                    && isxdigit(*(const unsigned char *)(src + i + 1))
                    && isxdigit(*(const unsigned char *)(src + i + 2))) {
                        a = tolower(*(const unsigned char *)(src + i + 1));
                        b = tolower(*(const unsigned char *)(src + i + 2));
                        dst[j] = (char)((HEXTOI(a) << 4) | HEXTOI(b));
                        i += 2;
                } else if (is_form_url_encoded && src[i] == '+') {
                        dst[j] = ' ';
                } else {
                        dst[j] = src[i];
                }
        }

        dst[j] = '\0'; /* Null-terminate the destination */

        return i >= src_len ? j : -1;
}


int
mg_get_var(const char *data,
           size_t data_len,
           const char *name,
           char *dst,
           size_t dst_len)
{
        return mg_get_var2(data, data_len, name, dst, dst_len, 0);
}


int
mg_get_var2(const char *data,
            size_t data_len,
            const char *name,
            char *dst,
            size_t dst_len,
            size_t occurrence)
{
        const char *p, *e, *s;
        size_t name_len;
        int len;

        if (dst == NULL || dst_len == 0) {
                len = -2;
        } else if (data == NULL || name == NULL || data_len == 0) {
                len = -1;
                dst[0] = '\0';
        } else {
                name_len = strlen(name);
                e = data + data_len;
                len = -1;
                dst[0] = '\0';

                /* data is "var1=val1&var2=val2...". Find variable first */
                for (p = data; p + name_len < e; p++) {
                        if ((p == data || p[-1] == '&') && p[name_len] == '='
                            && !mg_strncasecmp(name, p, name_len) && 0 == occurrence--) {
                                /* Point p to variable value */
                                p += name_len + 1;

                                /* Point s to the end of the value */
                                s = (const char *)memchr(p, '&', (size_t)(e - p));
                                if (s == NULL) {
                                        s = e;
                                }
                                /* assert(s >= p); */
                                if (s < p) {
                                        return -3;
                                }

                                /* Decode variable into destination buffer */
                                len = mg_url_decode(p, (int)(s - p), dst, (int)dst_len, 1);

                                /* Redirect error code from -1 to -2 (destination buffer too
                                 * small). */
                                if (len == -1) {
                                        len = -2;
                                }
                                break;
                        }
                }
        }

        return len;
}


int
mg_get_cookie(const char *cookie_header,
              const char *var_name,
              char *dst,
              size_t dst_size)
{
        const char *s, *p, *end;
        int name_len, len = -1;

        if (dst == NULL || dst_size == 0) {
                len = -2;
        } else if (var_name == NULL || (s = cookie_header) == NULL) {
                len = -1;
                dst[0] = '\0';
        } else {
                name_len = (int)strlen(var_name);
                end = s + strlen(s);
                dst[0] = '\0';

                for (; (s = mg_strcasestr(s, var_name)) != NULL; s += name_len) {
                        if (s[name_len] == '=') {
                                s += name_len + 1;
                                if ((p = strchr(s, ' ')) == NULL) {
                                        p = end;
                                }
                                if (p[-1] == ';') {
                                        p--;
                                }
                                if (*s == '"' && p[-1] == '"' && p > s + 1) {
                                        s++;
                                        p--;
                                }
                                if ((size_t)(p - s) < dst_size) {
                                        len = (int)(p - s);
                                        mg_strlcpy(dst, s, (size_t)len + 1);
                                } else {
                                        len = -3;
                                }
                                break;
                        }
                }
        }
        return len;
}


#if defined(USE_WEBSOCKET) || defined(USE_LUA)
static void
base64_encode(const unsigned char *src, int src_len, char *dst)
{
        static const char *b64 =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
        int i, j, a, b, c;

        for (i = j = 0; i < src_len; i += 3) {
                a = src[i];
                b = i + 1 >= src_len ? 0 : src[i + 1];
                c = i + 2 >= src_len ? 0 : src[i + 2];

                dst[j++] = b64[a >> 2];
                dst[j++] = b64[((a & 3) << 4) | (b >> 4)];
                if (i + 1 < src_len) {
                        dst[j++] = b64[(b & 15) << 2 | (c >> 6)];
                }
                if (i + 2 < src_len) {
                        dst[j++] = b64[c & 63];
                }
        }
        while (j % 4 != 0) {
                dst[j++] = '=';
        }
        dst[j++] = '\0';
}
#endif


#if defined(USE_LUA)
static unsigned char
b64reverse(char letter)
{
        if (letter >= 'A' && letter <= 'Z') {
                return letter - 'A';
        }
        if (letter >= 'a' && letter <= 'z') {
                return letter - 'a' + 26;
        }
        if (letter >= '0' && letter <= '9') {
                return letter - '0' + 52;
        }
        if (letter == '+') {
                return 62;
        }
        if (letter == '/') {
                return 63;
        }
        if (letter == '=') {
                return 255; /* normal end */
        }
        return 254; /* error */
}


static int
base64_decode(const unsigned char *src, int src_len, char *dst, size_t *dst_len)
{
        int i;
        unsigned char a, b, c, d;

        *dst_len = 0;

        for (i = 0; i < src_len; i += 4) {
                a = b64reverse(src[i]);
                if (a >= 254) {
                        return i;
                }

                b = b64reverse(i + 1 >= src_len ? 0 : src[i + 1]);
                if (b >= 254) {
                        return i + 1;
                }

                c = b64reverse(i + 2 >= src_len ? 0 : src[i + 2]);
                if (c == 254) {
                        return i + 2;
                }

                d = b64reverse(i + 3 >= src_len ? 0 : src[i + 3]);
                if (d == 254) {
                        return i + 3;
                }

                dst[(*dst_len)++] = (a << 2) + (b >> 4);
                if (c != 255) {
                        dst[(*dst_len)++] = (b << 4) + (c >> 2);
                        if (d != 255) {
                                dst[(*dst_len)++] = (c << 6) + d;
                        }
                }
        }
        return -1;
}
#endif


static int
is_put_or_delete_method(const struct mg_connection *conn)
{
        if (conn) {
                const char *s = conn->request_info.request_method;
                return s != NULL && (!strcmp(s, "PUT") || !strcmp(s, "DELETE")
                                     || !strcmp(s, "MKCOL") || !strcmp(s, "PATCH"));
        }
        return 0;
}


static void
interpret_uri(struct mg_connection *conn,   /* in: request (must be valid) */
              char *filename,               /* out: filename */
              size_t filename_buf_len,      /* in: size of filename buffer */
              struct file *filep,           /* out: file structure */
              int *is_found,                /* out: file is found (directly) */
              int *is_script_resource,      /* out: handled by a script? */
              int *is_websocket_request,    /* out: websocket connetion? */
              int *is_put_or_delete_request /* out: put/delete a file? */
              )
{
/* TODO (high): Restructure this function */

#if !defined(NO_FILES)
        const char *uri = conn->request_info.local_uri;
        const char *root = conn->ctx->config[DOCUMENT_ROOT];
        const char *rewrite;
        struct vec a, b;
        int match_len;
        char gz_path[PATH_MAX];
        char const *accept_encoding;
        int truncated;
#if !defined(NO_CGI) || defined(USE_LUA)
        char *p;
#endif
#else
        (void)filename_buf_len; /* unused if NO_FILES is defined */
#endif

        memset(filep, 0, sizeof(*filep));
        *filename = 0;
        *is_found = 0;
        *is_script_resource = 0;
        *is_put_or_delete_request = is_put_or_delete_method(conn);

#if defined(USE_WEBSOCKET)
        *is_websocket_request = is_websocket_protocol(conn);
#if !defined(NO_FILES)
        if (*is_websocket_request && conn->ctx->config[WEBSOCKET_ROOT]) {
                root = conn->ctx->config[WEBSOCKET_ROOT];
        }
#endif /* !NO_FILES */
#else  /* USE_WEBSOCKET */
        *is_websocket_request = 0;
#endif /* USE_WEBSOCKET */

#if !defined(NO_FILES)
        /* Note that root == NULL is a regular use case here. This occurs,
         * if all requests are handled by callbacks, so the WEBSOCKET_ROOT
         * config is not required. */
        if (root == NULL) {
                /* all file related outputs have already been set to 0, just return
                 */
                return;
        }

        /* Using buf_len - 1 because memmove() for PATH_INFO may shift part
         * of the path one byte on the right.
         * If document_root is NULL, leave the file empty. */
        mg_snprintf(
            conn, &truncated, filename, filename_buf_len - 1, "%s%s", root, uri);

        if (truncated) {
                goto interpret_cleanup;
        }

        rewrite = conn->ctx->config[REWRITE];
        while ((rewrite = next_option(rewrite, &a, &b)) != NULL) {
                if ((match_len = match_prefix(a.ptr, a.len, uri)) > 0) {
                        mg_snprintf(conn,
                                    &truncated,
                                    filename,
                                    filename_buf_len - 1,
                                    "%.*s%s",
                                    (int)b.len,
                                    b.ptr,
                                    uri + match_len);
                        break;
                }
        }

        if (truncated) {
                goto interpret_cleanup;
        }

        /* Local file path and name, corresponding to requested URI
         * is now stored in "filename" variable. */
        if (mg_stat(conn, filename, filep)) {
#if !defined(NO_CGI) || defined(USE_LUA) || defined(USE_DUKTAPE)
                /* File exists. Check if it is a script type. */
                if (0
#if !defined(NO_CGI)
                    || match_prefix(conn->ctx->config[CGI_EXTENSIONS],
                                    strlen(conn->ctx->config[CGI_EXTENSIONS]),
                                    filename) > 0
#endif
#if defined(USE_LUA)
                    || match_prefix(conn->ctx->config[LUA_SCRIPT_EXTENSIONS],
                                    strlen(conn->ctx->config[LUA_SCRIPT_EXTENSIONS]),
                                    filename) > 0
#endif
#if defined(USE_DUKTAPE)
                    || match_prefix(conn->ctx->config[DUKTAPE_SCRIPT_EXTENSIONS],
                                    strlen(
                                        conn->ctx->config[DUKTAPE_SCRIPT_EXTENSIONS]),
                                    filename) > 0
#endif
                    ) {
                        /* The request addresses a CGI script or a Lua script. The URI
                         * corresponds to the script itself (like /path/script.cgi),
                         * and there is no additional resource path
                         * (like /path/script.cgi/something).
                         * Requests that modify (replace or delete) a resource, like
                         * PUT and DELETE requests, should replace/delete the script
                         * file.
                         * Requests that read or write from/to a resource, like GET and
                         * POST requests, should call the script and return the
                         * generated response. */
                        *is_script_resource = !*is_put_or_delete_request;
                }
#endif /* !defined(NO_CGI) || defined(USE_LUA) || defined(USE_DUKTAPE) */
                *is_found = 1;
                return;
        }

        /* If we can't find the actual file, look for the file
         * with the same name but a .gz extension. If we find it,
         * use that and set the gzipped flag in the file struct
         * to indicate that the response need to have the content-
         * encoding: gzip header.
         * We can only do this if the browser declares support. */
        if ((accept_encoding = mg_get_header(conn, "Accept-Encoding")) != NULL) {
                if (strstr(accept_encoding, "gzip") != NULL) {
                        mg_snprintf(
                            conn, &truncated, gz_path, sizeof(gz_path), "%s.gz", filename);

                        if (truncated) {
                                goto interpret_cleanup;
                        }

                        if (mg_stat(conn, gz_path, filep)) {
                                if (filep) {
                                        filep->gzipped = 1;
                                        *is_found = 1;
                                }
                                /* Currently gz files can not be scripts. */
                                return;
                        }
                }
        }

#if !defined(NO_CGI) || defined(USE_LUA) || defined(USE_DUKTAPE)
        /* Support PATH_INFO for CGI scripts. */
        for (p = filename + strlen(filename); p > filename + 1; p--) {
                if (*p == '/') {
                        *p = '\0';
                        if ((0
#if !defined(NO_CGI)
                             || match_prefix(conn->ctx->config[CGI_EXTENSIONS],
                                             strlen(conn->ctx->config[CGI_EXTENSIONS]),
                                             filename) > 0
#endif
#if defined(USE_LUA)
                             || match_prefix(conn->ctx->config[LUA_SCRIPT_EXTENSIONS],
                                             strlen(
                                                 conn->ctx->config[LUA_SCRIPT_EXTENSIONS]),
                                             filename) > 0
#endif
#if defined(USE_DUKTAPE)
                             || match_prefix(
                                    conn->ctx->config[DUKTAPE_SCRIPT_EXTENSIONS],
                                    strlen(conn->ctx->config[DUKTAPE_SCRIPT_EXTENSIONS]),
                                    filename) > 0
#endif
                             ) && mg_stat(conn, filename, filep)) {
                                /* Shift PATH_INFO block one character right, e.g.
                                 * "/x.cgi/foo/bar\x00" => "/x.cgi\x00/foo/bar\x00"
                                 * conn->path_info is pointing to the local variable "path"
                                 * declared in handle_request(), so PATH_INFO is not valid
                                 * after handle_request returns. */
                                conn->path_info = p + 1;
                                memmove(p + 2, p + 1, strlen(p + 1) + 1); /* +1 is for
                                                                           * trailing \0 */
                                p[1] = '/';
                                *is_script_resource = 1;
                                break;
                        } else {
                                *p = '/';
                        }
                }
        }
#endif /* !defined(NO_CGI) || defined(USE_LUA) || defined(USE_DUKTAPE) */
#endif /* !defined(NO_FILES) */
        return;

#if !defined(NO_FILES)
/* Reset all outputs */
interpret_cleanup:
        memset(filep, 0, sizeof(*filep));
        *filename = 0;
        *is_found = 0;
        *is_script_resource = 0;
        *is_websocket_request = 0;
        *is_put_or_delete_request = 0;
#endif /* !defined(NO_FILES) */
}


/* Check whether full request is buffered. Return:
 * -1  if request is malformed
 *  0  if request is not yet fully buffered
 * >0  actual request length, including last \r\n\r\n */
static int
get_request_len(const char *buf, int buflen)
{
        const char *s, *e;
        int len = 0;
        int in_content = 0;

        for (s = buf, e = s + buflen - 1; len <= 0 && s < e; s++) {
                /* Control characters are not allowed but >=128 is. */
                if (!in_content && !isprint(*(const unsigned char *)s) && *s != '\r'
                    && *s != '\n'
                    && *(const unsigned char *)s < 128) {
                        len = -1;
                        break; /* [i_a] abort scan as soon as one malformed character is
                               * found; */
                        /* don't let subsequent \r\n\r\n win us over anyhow */
                } else if (s[0] == '\n' && s[1] == '\n') {
                        len = (int)(s - buf) + 2;
                } else if (s[0] == '\n' && &s[1] < e && s[1] == '\r' && s[2] == '\n') {
                        len = (int)(s - buf) + 3;
                        in_content = 0;
                }

                if (!in_content && *s == ':') {
                        in_content = 1;
                }
        }

        return len;
}


#if !defined(NO_CACHING)
/* Convert month to the month number. Return -1 on error, or month number */
static int
get_month_index(const char *s)
{
        size_t i;

        for (i = 0; i < ARRAY_SIZE(month_names); i++) {
                if (!strcmp(s, month_names[i])) {
                        return (int)i;
                }
        }

        return -1;
}


/* Parse UTC date-time string, and return the corresponding time_t value. */
static time_t
parse_date_string(const char *datetime)
{
        char month_str[32] = {0};
        int second, minute, hour, day, month, year;
        time_t result = (time_t)0;
        struct tm tm;

        if ((sscanf(datetime,
                    "%d/%3s/%d %d:%d:%d",
                    &day,
                    month_str,
                    &year,
                    &hour,
                    &minute,
                    &second) == 6) || (sscanf(datetime,
                                              "%d %3s %d %d:%d:%d",
                                              &day,
                                              month_str,
                                              &year,
                                              &hour,
                                              &minute,
                                              &second) == 6)
            || (sscanf(datetime,
                       "%*3s, %d %3s %d %d:%d:%d",
                       &day,
                       month_str,
                       &year,
                       &hour,
                       &minute,
                       &second) == 6) || (sscanf(datetime,
                                                 "%d-%3s-%d %d:%d:%d",
                                                 &day,
                                                 month_str,
                                                 &year,
                                                 &hour,
                                                 &minute,
                                                 &second) == 6)) {
                month = get_month_index(month_str);
                if ((month >= 0) && (year >= 1970)) {
                        memset(&tm, 0, sizeof(tm));
                        tm.tm_year = year - 1900;
                        tm.tm_mon = month;
                        tm.tm_mday = day;
                        tm.tm_hour = hour;
                        tm.tm_min = minute;
                        tm.tm_sec = second;
                        result = timegm(&tm);
                }
        }

        return result;
}
#endif /* !NO_CACHING */


/* Protect against directory disclosure attack by removing '..',
 * excessive '/' and '\' characters */
static void
remove_double_dots_and_double_slashes(char *s)
{
        char *p = s;

        while (*s != '\0') {
                *p++ = *s++;
                if (s[-1] == '/' || s[-1] == '\\') {
                        /* Skip all following slashes, backslashes and double-dots */
                        while (s[0] != '\0') {
                                if (s[0] == '/' || s[0] == '\\') {
                                        s++;
                                } else if (s[0] == '.' && s[1] == '.') {
                                        s += 2;
                                } else {
                                        break;
                                }
                        }
                }
        }
        *p = '\0';
}


static const struct {
        const char *extension;
        size_t ext_len;
        const char *mime_type;
} builtin_mime_types[] = {
    /* IANA registered MIME types (http://www.iana.org/assignments/media-types)
     * application types */
    {".doc", 4, "application/msword"},
    {".eps", 4, "application/postscript"},
    {".exe", 4, "application/octet-stream"},
    {".js", 3, "application/javascript"},
    {".json", 5, "application/json"},
    {".pdf", 4, "application/pdf"},
    {".ps", 3, "application/postscript"},
    {".rtf", 4, "application/rtf"},
    {".xhtml", 6, "application/xhtml+xml"},
    {".xsl", 4, "application/xml"},
    {".xslt", 5, "application/xml"},

    /* fonts */
    {".ttf", 4, "application/font-sfnt"},
    {".cff", 4, "application/font-sfnt"},
    {".otf", 4, "application/font-sfnt"},
    {".aat", 4, "application/font-sfnt"},
    {".sil", 4, "application/font-sfnt"},
    {".pfr", 4, "application/font-tdpfr"},
    {".woff", 5, "application/font-woff"},

    /* audio */
    {".mp3", 4, "audio/mpeg"},
    {".oga", 4, "audio/ogg"},
    {".ogg", 4, "audio/ogg"},

    /* image */
    {".gif", 4, "image/gif"},
    {".ief", 4, "image/ief"},
    {".jpeg", 5, "image/jpeg"},
    {".jpg", 4, "image/jpeg"},
    {".jpm", 4, "image/jpm"},
    {".jpx", 4, "image/jpx"},
    {".png", 4, "image/png"},
    {".svg", 4, "image/svg+xml"},
    {".tif", 4, "image/tiff"},
    {".tiff", 5, "image/tiff"},

    /* model */
    {".wrl", 4, "model/vrml"},

    /* text */
    {".css", 4, "text/css"},
    {".csv", 4, "text/csv"},
    {".htm", 4, "text/html"},
    {".html", 5, "text/html"},
    {".sgm", 4, "text/sgml"},
    {".shtm", 5, "text/html"},
    {".shtml", 6, "text/html"},
    {".txt", 4, "text/plain"},
    {".xml", 4, "text/xml"},

    /* video */
    {".mov", 4, "video/quicktime"},
    {".mp4", 4, "video/mp4"},
    {".mpeg", 5, "video/mpeg"},
    {".mpg", 4, "video/mpeg"},
    {".ogv", 4, "video/ogg"},
    {".qt", 3, "video/quicktime"},

    /* not registered types
     * (http://reference.sitepoint.com/html/mime-types-full,
     * http://www.hansenb.pdx.edu/DMKB/dict/tutorials/mime_typ.php, ..) */
    {".arj", 4, "application/x-arj-compressed"},
    {".gz", 3, "application/x-gunzip"},
    {".rar", 4, "application/x-arj-compressed"},
    {".swf", 4, "application/x-shockwave-flash"},
    {".tar", 4, "application/x-tar"},
    {".tgz", 4, "application/x-tar-gz"},
    {".torrent", 8, "application/x-bittorrent"},
    {".ppt", 4, "application/x-mspowerpoint"},
    {".xls", 4, "application/x-msexcel"},
    {".zip", 4, "application/x-zip-compressed"},
    {".aac",
     4,
     "audio/aac"}, /* http://en.wikipedia.org/wiki/Advanced_Audio_Coding */
    {".aif", 4, "audio/x-aif"},
    {".m3u", 4, "audio/x-mpegurl"},
    {".mid", 4, "audio/x-midi"},
    {".ra", 3, "audio/x-pn-realaudio"},
    {".ram", 4, "audio/x-pn-realaudio"},
    {".wav", 4, "audio/x-wav"},
    {".bmp", 4, "image/bmp"},
    {".ico", 4, "image/x-icon"},
    {".pct", 4, "image/x-pct"},
    {".pict", 5, "image/pict"},
    {".rgb", 4, "image/x-rgb"},
    {".webm", 5, "video/webm"}, /* http://en.wikipedia.org/wiki/WebM */
    {".asf", 4, "video/x-ms-asf"},
    {".avi", 4, "video/x-msvideo"},
    {".m4v", 4, "video/x-m4v"},
    {NULL, 0, NULL}};


const char *
mg_get_builtin_mime_type(const char *path)
{
        const char *ext;
        size_t i, path_len;

        path_len = strlen(path);

        for (i = 0; builtin_mime_types[i].extension != NULL; i++) {
                ext = path + (path_len - builtin_mime_types[i].ext_len);
                if (path_len > builtin_mime_types[i].ext_len
                    && mg_strcasecmp(ext, builtin_mime_types[i].extension) == 0) {
                        return builtin_mime_types[i].mime_type;
                }
        }

        return "text/plain";
}


/* Look at the "path" extension and figure what mime type it has.
 * Store mime type in the vector. */
static void
get_mime_type(struct mg_context *ctx, const char *path, struct vec *vec)
{
        struct vec ext_vec, mime_vec;
        const char *list, *ext;
        size_t path_len;

        path_len = strlen(path);

        if (ctx == NULL || vec == NULL) {
                return;
        }

        /* Scan user-defined mime types first, in case user wants to
         * override default mime types. */
        list = ctx->config[EXTRA_MIME_TYPES];
        while ((list = next_option(list, &ext_vec, &mime_vec)) != NULL) {
                /* ext now points to the path suffix */
                ext = path + path_len - ext_vec.len;
                if (mg_strncasecmp(ext, ext_vec.ptr, ext_vec.len) == 0) {
                        *vec = mime_vec;
                        return;
                }
        }

        vec->ptr = mg_get_builtin_mime_type(path);
        vec->len = strlen(vec->ptr);
}


/* Stringify binary data. Output buffer must be twice as big as input,
 * because each byte takes 2 bytes in string representation */
static void
bin2str(char *to, const unsigned char *p, size_t len)
{
        static const char *hex = "0123456789abcdef";

        for (; len--; p++) {
                *to++ = hex[p[0] >> 4];
                *to++ = hex[p[0] & 0x0f];
        }
        *to = '\0';
}


/* Return stringified MD5 hash for list of strings. Buffer must be 33 bytes. */
char *
mg_md5(char buf[33], ...)
{
        md5_byte_t hash[16];
        const char *p;
        va_list ap;
        md5_state_t ctx;

        md5_init(&ctx);

        va_start(ap, buf);
        while ((p = va_arg(ap, const char *)) != NULL) {
                md5_append(&ctx, (const md5_byte_t *)p, strlen(p));
        }
        va_end(ap);

        md5_finish(&ctx, hash);
        bin2str(buf, hash, sizeof(hash));
        return buf;
}


/* Check the user's password, return 1 if OK */
static int
check_password(const char *method,
               const char *ha1,
               const char *uri,
               const char *nonce,
               const char *nc,
               const char *cnonce,
               const char *qop,
               const char *response)
{
        char ha2[32 + 1], expected_response[32 + 1];

        /* Some of the parameters may be NULL */
        if (method == NULL || nonce == NULL || nc == NULL || cnonce == NULL
            || qop == NULL
            || response == NULL) {
                return 0;
        }

        /* NOTE(lsm): due to a bug in MSIE, we do not compare the URI */
        if (strlen(response) != 32) {
                return 0;
        }

        mg_md5(ha2, method, ":", uri, NULL);
        mg_md5(expected_response,
               ha1,
               ":",
               nonce,
               ":",
               nc,
               ":",
               cnonce,
               ":",
               qop,
               ":",
               ha2,
               NULL);

        return mg_strcasecmp(response, expected_response) == 0;
}


/* Use the global passwords file, if specified by auth_gpass option,
 * or search for .htpasswd in the requested directory. */
static void
open_auth_file(struct mg_connection *conn, const char *path, struct file *filep)
{
        if (conn != NULL && conn->ctx != NULL) {
                char name[PATH_MAX];
                const char *p, *e, *gpass = conn->ctx->config[GLOBAL_PASSWORDS_FILE];
                struct file file = STRUCT_FILE_INITIALIZER;
                int truncated;

                if (gpass != NULL) {
                        /* Use global passwords file */
                        if (!mg_fopen(conn, gpass, "r", filep)) {
#ifdef DEBUG
                                mg_cry(conn, "fopen(%s): %s", gpass, strerror(ERRNO));
#endif
                        }
                        /* Important: using local struct file to test path for is_directory
                         * flag. If filep is used, mg_stat() makes it appear as if auth file
                         * was opened. */
                } else if (mg_stat(conn, path, &file) && file.is_directory) {
                        mg_snprintf(conn,
                                    &truncated,
                                    name,
                                    sizeof(name),
                                    "%s/%s",
                                    path,
                                    PASSWORDS_FILE_NAME);

                        if (truncated || !mg_fopen(conn, name, "r", filep)) {
#ifdef DEBUG
                                mg_cry(conn, "fopen(%s): %s", name, strerror(ERRNO));
#endif
                        }
                } else {
                        /* Try to find .htpasswd in requested directory. */
                        for (p = path, e = p + strlen(p) - 1; e > p; e--) {
                                if (e[0] == '/') {
                                        break;
                                }
                        }
                        mg_snprintf(conn,
                                    &truncated,
                                    name,
                                    sizeof(name),
                                    "%.*s/%s",
                                    (int)(e - p),
                                    p,
                                    PASSWORDS_FILE_NAME);

                        if (truncated || !mg_fopen(conn, name, "r", filep)) {
#ifdef DEBUG
                                mg_cry(conn, "fopen(%s): %s", name, strerror(ERRNO));
#endif
                        }
                }
        }
}


/* Parsed Authorization header */
struct ah {
        char *user, *uri, *cnonce, *response, *qop, *nc, *nonce;
};


/* Return 1 on success. Always initializes the ah structure. */
static int
parse_auth_header(struct mg_connection *conn,
                  char *buf,
                  size_t buf_size,
                  struct ah *ah)
{
        char *name, *value, *s;
        const char *auth_header;
        uint64_t nonce;

        if (!ah || !conn) {
                return 0;
        }

        (void)memset(ah, 0, sizeof(*ah));
        if ((auth_header = mg_get_header(conn, "Authorization")) == NULL
            || mg_strncasecmp(auth_header, "Digest ", 7) != 0) {
                return 0;
        }

        /* Make modifiable copy of the auth header */
        (void)mg_strlcpy(buf, auth_header + 7, buf_size);
        s = buf;

        /* Parse authorization header */
        for (;;) {
                /* Gobble initial spaces */
                while (isspace(*(unsigned char *)s)) {
                        s++;
                }
                name = skip_quoted(&s, "=", " ", 0);
                /* Value is either quote-delimited, or ends at first comma or space. */
                if (s[0] == '\"') {
                        s++;
                        value = skip_quoted(&s, "\"", " ", '\\');
                        if (s[0] == ',') {
                                s++;
                        }
                } else {
                        value = skip_quoted(&s, ", ", " ", 0); /* IE uses commas, FF uses
                                                                * spaces */
                }
                if (*name == '\0') {
                        break;
                }

                if (!strcmp(name, "username")) {
                        ah->user = value;
                } else if (!strcmp(name, "cnonce")) {
                        ah->cnonce = value;
                } else if (!strcmp(name, "response")) {
                        ah->response = value;
                } else if (!strcmp(name, "uri")) {
                        ah->uri = value;
                } else if (!strcmp(name, "qop")) {
                        ah->qop = value;
                } else if (!strcmp(name, "nc")) {
                        ah->nc = value;
                } else if (!strcmp(name, "nonce")) {
                        ah->nonce = value;
                }
        }

#ifndef NO_NONCE_CHECK
        /* Read the nonce from the response. */
        if (ah->nonce == NULL) {
                return 0;
        }
        s = NULL;
        nonce = strtoull(ah->nonce, &s, 10);
        if ((s == NULL) || (*s != 0)) {
                return 0;
        }

        /* Convert the nonce from the client to a number. */
        nonce ^= conn->ctx->auth_nonce_mask;

        /* The converted number corresponds to the time the nounce has been
         * created. This should not be earlier than the server start. */
        /* Server side nonce check is valuable in all situations but one:
         * if the server restarts frequently, but the client should not see
         * that, so the server should accept nonces from previous starts. */
        /* However, the reasonable default is to not accept a nonce from a
         * previous start, so if anyone changed the access rights between
         * two restarts, a new login is required. */
        if (nonce < (uint64_t)conn->ctx->start_time) {
                /* nonce is from a previous start of the server and no longer valid
                 * (replay attack?) */
                return 0;
        }
        /* Check if the nonce is too high, so it has not (yet) been used by the
         * server. */
        if (nonce >= ((uint64_t)conn->ctx->start_time + conn->ctx->nonce_count)) {
                return 0;
        }
#endif

        /* CGI needs it as REMOTE_USER */
        if (ah->user != NULL) {
                conn->request_info.remote_user = mg_strdup(ah->user);
        } else {
                return 0;
        }

        return 1;
}


static const char *
mg_fgets(char *buf, size_t size, struct file *filep, char **p)
{
        const char *eof;
        size_t len;
        const char *memend;

        if (!filep) {
                return NULL;
        }

        if (filep->membuf != NULL && *p != NULL) {
                memend = (const char *)&filep->membuf[filep->size];
                /* Search for \n from p till the end of stream */
                eof = (char *)memchr(*p, '\n', (size_t)(memend - *p));
                if (eof != NULL) {
                        eof += 1; /* Include \n */
                } else {
                        eof = memend; /* Copy remaining data */
                }
                len = (size_t)(eof - *p) > size - 1 ? size - 1 : (size_t)(eof - *p);
                memcpy(buf, *p, len);
                buf[len] = '\0';
                *p += len;
                return len ? eof : NULL;
        } else if (filep->fp != NULL) {
                return fgets(buf, (int)size, filep->fp);
        } else {
                return NULL;
        }
}

struct read_auth_file_struct {
        struct mg_connection *conn;
        struct ah ah;
        char *domain;
        char buf[256 + 256 + 40];
        char *f_user;
        char *f_domain;
        char *f_ha1;
};


static int
read_auth_file(struct file *filep, struct read_auth_file_struct *workdata)
{
        char *p;
        int is_authorized = 0;
        struct file fp;
        size_t l;

        if (!filep || !workdata) {
                return 0;
        }

        /* Loop over passwords file */
        p = (char *)filep->membuf;
        while (mg_fgets(workdata->buf, sizeof(workdata->buf), filep, &p) != NULL) {
                l = strlen(workdata->buf);
                while (l > 0) {
                        if (isspace(workdata->buf[l - 1])
                            || iscntrl(workdata->buf[l - 1])) {
                                l--;
                                workdata->buf[l] = 0;
                        } else
                                break;
                }
                if (l < 1) {
                        continue;
                }

                workdata->f_user = workdata->buf;

                if (workdata->f_user[0] == ':') {
                        /* user names may not contain a ':' and may not be empty,
                         * so lines starting with ':' may be used for a special purpose */
                        if (workdata->f_user[1] == '#') {
                                /* :# is a comment */
                                continue;
                        } else if (!strncmp(workdata->f_user + 1, "include=", 8)) {
                                if (mg_fopen(workdata->conn, workdata->f_user + 9, "r", &fp)) {
                                        is_authorized = read_auth_file(&fp, workdata);
                                        mg_fclose(&fp);
                                } else {
                                        mg_cry(workdata->conn,
                                               "%s: cannot open authorization file: %s",
                                               __func__,
                                               workdata->buf);
                                }
                                continue;
                        }
                        /* everything is invalid for the moment (might change in the
                         * future) */
                        mg_cry(workdata->conn,
                               "%s: syntax error in authorization file: %s",
                               __func__,
                               workdata->buf);
                        continue;
                }

                workdata->f_domain = strchr(workdata->f_user, ':');
                if (workdata->f_domain == NULL) {
                        mg_cry(workdata->conn,
                               "%s: syntax error in authorization file: %s",
                               __func__,
                               workdata->buf);
                        continue;
                }
                *(workdata->f_domain) = 0;
                (workdata->f_domain)++;

                workdata->f_ha1 = strchr(workdata->f_domain, ':');
                if (workdata->f_ha1 == NULL) {
                        mg_cry(workdata->conn,
                               "%s: syntax error in authorization file: %s",
                               __func__,
                               workdata->buf);
                        continue;
                }
                *(workdata->f_ha1) = 0;
                (workdata->f_ha1)++;

                if (!strcmp(workdata->ah.user, workdata->f_user)
                    && !strcmp(workdata->domain, workdata->f_domain)) {
                        return check_password(workdata->conn->request_info.request_method,
                                              workdata->f_ha1,
                                              workdata->ah.uri,
                                              workdata->ah.nonce,
                                              workdata->ah.nc,
                                              workdata->ah.cnonce,
                                              workdata->ah.qop,
                                              workdata->ah.response);
                }
        }

        return is_authorized;
}


/* Authorize against the opened passwords file. Return 1 if authorized. */
static int
authorize(struct mg_connection *conn, struct file *filep)
{
        struct read_auth_file_struct workdata;
        char buf[MG_BUF_LEN];

        if (!conn || !conn->ctx) {
                return 0;
        }

        memset(&workdata, 0, sizeof(workdata));
        workdata.conn = conn;

        if (!parse_auth_header(conn, buf, sizeof(buf), &workdata.ah)) {
                return 0;
        }
        workdata.domain = conn->ctx->config[AUTHENTICATION_DOMAIN];

        return read_auth_file(filep, &workdata);
}


/* Return 1 if request is authorised, 0 otherwise. */
static int
check_authorization(struct mg_connection *conn, const char *path)
{
        char fname[PATH_MAX];
        struct vec uri_vec, filename_vec;
        const char *list;
        struct file file = STRUCT_FILE_INITIALIZER;
        int authorized = 1, truncated;

        if (!conn || !conn->ctx) {
                return 0;
        }

        list = conn->ctx->config[PROTECT_URI];
        while ((list = next_option(list, &uri_vec, &filename_vec)) != NULL) {
                if (!memcmp(conn->request_info.local_uri, uri_vec.ptr, uri_vec.len)) {
                        mg_snprintf(conn,
                                    &truncated,
                                    fname,
                                    sizeof(fname),
                                    "%.*s",
                                    (int)filename_vec.len,
                                    filename_vec.ptr);

                        if (truncated || !mg_fopen(conn, fname, "r", &file)) {
                                mg_cry(conn,
                                       "%s: cannot open %s: %s",
                                       __func__,
                                       fname,
                                       strerror(errno));
                        }
                        break;
                }
        }

        if (!is_file_opened(&file)) {
                open_auth_file(conn, path, &file);
        }

        if (is_file_opened(&file)) {
                authorized = authorize(conn, &file);
                mg_fclose(&file);
        }

        return authorized;
}


static void
send_authorization_request(struct mg_connection *conn)
{
        char date[64];
        time_t curtime = time(NULL);

        if (conn && conn->ctx) {
                uint64_t nonce = (uint64_t)(conn->ctx->start_time);

                (void)pthread_mutex_lock(&conn->ctx->nonce_mutex);
                nonce += conn->ctx->nonce_count;
                ++conn->ctx->nonce_count;
                (void)pthread_mutex_unlock(&conn->ctx->nonce_mutex);

                nonce ^= conn->ctx->auth_nonce_mask;
                conn->status_code = 401;
                conn->must_close = 1;

                gmt_time_string(date, sizeof(date), &curtime);

                mg_printf(conn, "HTTP/1.1 401 Unauthorized\r\n");
                send_no_cache_header(conn);
                mg_printf(conn,
                          "Date: %s\r\n"
                          "Connection: %s\r\n"
                          "Content-Length: 0\r\n"
                          "WWW-Authenticate: Digest qop=\"auth\", realm=\"%s\", "
                          "nonce=\"%" UINT64_FMT "\"\r\n\r\n",
                          date,
                          suggest_connection_header(conn),
                          conn->ctx->config[AUTHENTICATION_DOMAIN],
                          nonce);
        }
}


#if !defined(NO_FILES)
static int
is_authorized_for_put(struct mg_connection *conn)
{
        if (conn) {
                struct file file = STRUCT_FILE_INITIALIZER;
                const char *passfile = conn->ctx->config[PUT_DELETE_PASSWORDS_FILE];
                int ret = 0;

                if (passfile != NULL && mg_fopen(conn, passfile, "r", &file)) {
                        ret = authorize(conn, &file);
                        mg_fclose(&file);
                }

                return ret;
        }
        return 0;
}
#endif


int
mg_modify_passwords_file(const char *fname,
                         const char *domain,
                         const char *user,
                         const char *pass)
{
        int found, i;
        char line[512], u[512] = "", d[512] = "", ha1[33], tmp[PATH_MAX + 8];
        FILE *fp, *fp2;

        found = 0;
        fp = fp2 = NULL;

        /* Regard empty password as no password - remove user record. */
        if (pass != NULL && pass[0] == '\0') {
                pass = NULL;
        }

        /* Other arguments must not be empty */
        if (fname == NULL || domain == NULL || user == NULL) {
                return 0;
        }

        /* Using the given file format, user name and domain must not contain ':'
         */
        if (strchr(user, ':') != NULL) {
                return 0;
        }
        if (strchr(domain, ':') != NULL) {
                return 0;
        }

        /* Do not allow control characters like newline in user name and domain.
         * Do not allow excessively long names either. */
        for (i = 0; i < 255 && user[i] != 0; i++) {
                if (iscntrl(user[i])) {
                        return 0;
                }
        }
        if (user[i]) {
                return 0;
        }
        for (i = 0; i < 255 && domain[i] != 0; i++) {
                if (iscntrl(domain[i])) {
                        return 0;
                }
        }
        if (domain[i]) {
                return 0;
        }

        /* The maximum length of the path to the password file is limited */
        if ((strlen(fname) + 4) >= PATH_MAX) {
                return 0;
        }

        /* Create a temporary file name. Length has been checked before. */
        strcpy(tmp, fname);
        strcat(tmp, ".tmp");

        /* Create the file if does not exist */
        /* Use of fopen here is OK, since fname is only ASCII */
        if ((fp = fopen(fname, "a+")) != NULL) {
                (void)fclose(fp);
        }

        /* Open the given file and temporary file */
        if ((fp = fopen(fname, "r")) == NULL) {
                return 0;
        } else if ((fp2 = fopen(tmp, "w+")) == NULL) {
                fclose(fp);
                return 0;
        }

        /* Copy the stuff to temporary file */
        while (fgets(line, sizeof(line), fp) != NULL) {
                if (sscanf(line, "%255[^:]:%255[^:]:%*s", u, d) != 2) {
                        continue;
                }
                u[255] = 0;
                d[255] = 0;

                if (!strcmp(u, user) && !strcmp(d, domain)) {
                        found++;
                        if (pass != NULL) {
                                mg_md5(ha1, user, ":", domain, ":", pass, NULL);
                                fprintf(fp2, "%s:%s:%s\n", user, domain, ha1);
                        }
                } else {
                        fprintf(fp2, "%s", line);
                }
        }

        /* If new user, just add it */
        if (!found && pass != NULL) {
                mg_md5(ha1, user, ":", domain, ":", pass, NULL);
                fprintf(fp2, "%s:%s:%s\n", user, domain, ha1);
        }

        /* Close files */
        fclose(fp);
        fclose(fp2);

        /* Put the temp file in place of real file */
        IGNORE_UNUSED_RESULT(remove(fname));
        IGNORE_UNUSED_RESULT(rename(tmp, fname));

        return 1;
}


static int
is_valid_port(unsigned long port)
{
        return port < 0xffff;
}


static int
mg_inet_pton(int af, const char *src, void *dst, size_t dstlen)
{
        struct addrinfo hints, *res, *ressave;
        int func_ret = 0;
        int gai_ret;

        memset(&hints, 0, sizeof(struct addrinfo));
        hints.ai_family = af;

        gai_ret = getaddrinfo(src, NULL, &hints, &res);
        if (gai_ret != 0) {
                /* gai_strerror could be used to convert gai_ret to a string */
                /* POSIX return values: see
                 * http://pubs.opengroup.org/onlinepubs/9699919799/functions/freeaddrinfo.html
                 */
                /* Windows return values: see
                 * https://msdn.microsoft.com/en-us/library/windows/desktop/ms738520%28v=vs.85%29.aspx
                 */
                return 0;
        }

        ressave = res;

        while (res) {
                if (dstlen >= res->ai_addrlen) {
                        memcpy(dst, res->ai_addr, res->ai_addrlen);
                        func_ret = 1;
                }
                res = res->ai_next;
        }

        freeaddrinfo(ressave);
        return func_ret;
}


static int
connect_socket(struct mg_context *ctx /* may be NULL */,
               const char *host,
               int port,
               int use_ssl,
               char *ebuf,
               size_t ebuf_len,
               SOCKET *sock /* output: socket, must not be NULL */,
               union usa *sa /* output: socket address, must not be NULL  */
               )
{
        int ip_ver = 0;
        *sock = INVALID_SOCKET;
        memset(sa, 0, sizeof(*sa));

        if (ebuf_len > 0) {
                *ebuf = 0;
        }

        if (host == NULL) {
                mg_snprintf(NULL,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "%s",
                            "NULL host");
                return 0;
        }

        if (port < 0 || !is_valid_port((unsigned)port)) {
                mg_snprintf(NULL,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "%s",
                            "invalid port");
                return 0;
        }

#ifndef NO_SSL_DL
        if (use_ssl && (SSLv23_client_method == NULL)) {
                mg_snprintf(NULL,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "%s",
                            "SSL is not initialized");
                return 0;
        }
#endif

        if (mg_inet_pton(AF_INET, host, &sa->sin, sizeof(sa->sin))) {
                sa->sin.sin_port = htons((uint16_t)port);
                ip_ver = 4;
#ifdef USE_IPV6
        } else if (mg_inet_pton(AF_INET6, host, &sa->sin6, sizeof(sa->sin6))) {
                sa->sin6.sin6_port = htons((uint16_t)port);
                ip_ver = 6;
        } else if (host[0] == '[') {
                /* While getaddrinfo on Windows will work with [::1],
                 * getaddrinfo on Linux only works with ::1 (without []). */
                size_t l = strlen(host + 1);
                char *h = l > 1 ? mg_strdup(host + 1) : NULL;
                if (h) {
                        h[l - 1] = 0;
                        if (mg_inet_pton(AF_INET6, h, &sa->sin6, sizeof(sa->sin6))) {
                                sa->sin6.sin6_port = htons((uint16_t)port);
                                ip_ver = 6;
                        }
                        mg_free(h);
                }
#endif
        }

        if (ip_ver == 0) {
                mg_snprintf(NULL,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "%s",
                            "host not found");
                return 0;
        }

        if (ip_ver == 4) {
                *sock = socket(PF_INET, SOCK_STREAM, 0);
        }
#ifdef USE_IPV6
        else if (ip_ver == 6) {
                *sock = socket(PF_INET6, SOCK_STREAM, 0);
        }
#endif

        if (*sock == INVALID_SOCKET) {
                mg_snprintf(NULL,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "socket(): %s",
                            strerror(ERRNO));
                return 0;
        }

        set_close_on_exec(*sock, fc(ctx));

        if ((ip_ver == 4)
            && (connect(*sock, (struct sockaddr *)&sa->sin, sizeof(sa->sin))
                == 0)) {
                /* connected with IPv4 */
                return 1;
        }

#ifdef USE_IPV6
        if ((ip_ver == 6)
            && (connect(*sock, (struct sockaddr *)&sa->sin6, sizeof(sa->sin6))
                == 0)) {
                /* connected with IPv6 */
                return 1;
        }
#endif

        /* Not connected */
        mg_snprintf(NULL,
                    NULL, /* No truncation check for ebuf */
                    ebuf,
                    ebuf_len,
                    "connect(%s:%d): %s",
                    host,
                    port,
                    strerror(ERRNO));
        closesocket(*sock);
        *sock = INVALID_SOCKET;
        return 0;
}


int
mg_url_encode(const char *src, char *dst, size_t dst_len)
{
        static const char *dont_escape = "._-$,;~()";
        static const char *hex = "0123456789abcdef";
        char *pos = dst;
        const char *end = dst + dst_len - 1;

        for (; *src != '\0' && pos < end; src++, pos++) {
                if (isalnum(*(const unsigned char *)src)
                    || strchr(dont_escape, *(const unsigned char *)src) != NULL) {
                        *pos = *src;
                } else if (pos + 2 < end) {
                        pos[0] = '%';
                        pos[1] = hex[(*(const unsigned char *)src) >> 4];
                        pos[2] = hex[(*(const unsigned char *)src) & 0xf];
                        pos += 2;
                } else {
                        break;
                }
        }

        *pos = '\0';
        return (*src == '\0') ? (int)(pos - dst) : -1;
}


static void
print_dir_entry(struct de *de)
{
        char size[64], mod[64], href[PATH_MAX];
        struct tm *tm;

        if (de->file.is_directory) {
                mg_snprintf(de->conn,
                            NULL, /* Buffer is big enough */
                            size,
                            sizeof(size),
                            "%s",
                            "[DIRECTORY]");
        } else {
                /* We use (signed) cast below because MSVC 6 compiler cannot
                 * convert unsigned __int64 to double. Sigh. */
                if (de->file.size < 1024) {
                        mg_snprintf(de->conn,
                                    NULL, /* Buffer is big enough */
                                    size,
                                    sizeof(size),
                                    "%d",
                                    (int)de->file.size);
                } else if (de->file.size < 0x100000) {
                        mg_snprintf(de->conn,
                                    NULL, /* Buffer is big enough */
                                    size,
                                    sizeof(size),
                                    "%.1fk",
                                    (double)de->file.size / 1024.0);
                } else if (de->file.size < 0x40000000) {
                        mg_snprintf(de->conn,
                                    NULL, /* Buffer is big enough */
                                    size,
                                    sizeof(size),
                                    "%.1fM",
                                    (double)de->file.size / 1048576);
                } else {
                        mg_snprintf(de->conn,
                                    NULL, /* Buffer is big enough */
                                    size,
                                    sizeof(size),
                                    "%.1fG",
                                    (double)de->file.size / 1073741824);
                }
        }

        /* Note: mg_snprintf will not cause a buffer overflow above.
         * So, string truncation checks are not required here. */

        tm = localtime(&de->file.last_modified);
        if (tm != NULL) {
                strftime(mod, sizeof(mod), "%d-%b-%Y %H:%M", tm);
        } else {
                mg_strlcpy(mod, "01-Jan-1970 00:00", sizeof(mod));
                mod[sizeof(mod) - 1] = '\0';
        }
        mg_url_encode(de->file_name, href, sizeof(href));
        de->conn->num_bytes_sent +=
            mg_printf(de->conn,
                      "<tr><td><a href=\"%s%s%s\">%s%s</a></td>"
                      "<td>&nbsp;%s</td><td>&nbsp;&nbsp;%s</td></tr>\n",
                      de->conn->request_info.local_uri,
                      href,
                      de->file.is_directory ? "/" : "",
                      de->file_name,
                      de->file.is_directory ? "/" : "",
                      mod,
                      size);
}


/* This function is called from send_directory() and used for
 * sorting directory entries by size, or name, or modification time.
 * On windows, __cdecl specification is needed in case if project is built
 * with __stdcall convention. qsort always requires __cdels callback. */
static int WINCDECL
compare_dir_entries(const void *p1, const void *p2)
{
        if (p1 && p2) {
                const struct de *a = (const struct de *)p1, *b = (const struct de *)p2;
                const char *query_string = a->conn->request_info.query_string;
                int cmp_result = 0;

                if (query_string == NULL) {
                        query_string = "na";
                }

                if (a->file.is_directory && !b->file.is_directory) {
                        return -1; /* Always put directories on top */
                } else if (!a->file.is_directory && b->file.is_directory) {
                        return 1; /* Always put directories on top */
                } else if (*query_string == 'n') {
                        cmp_result = strcmp(a->file_name, b->file_name);
                } else if (*query_string == 's') {
                        cmp_result = a->file.size == b->file.size
                                         ? 0
                                         : a->file.size > b->file.size ? 1 : -1;
                } else if (*query_string == 'd') {
                        cmp_result =
                            (a->file.last_modified == b->file.last_modified)
                                ? 0
                                : ((a->file.last_modified > b->file.last_modified) ? 1
                                                                                   : -1);
                }

                return query_string[1] == 'd' ? -cmp_result : cmp_result;
        }
        return 0;
}


static int
must_hide_file(struct mg_connection *conn, const char *path)
{
        if (conn && conn->ctx) {
                const char *pw_pattern = "**" PASSWORDS_FILE_NAME "$";
                const char *pattern = conn->ctx->config[HIDE_FILES];
                return match_prefix(pw_pattern, strlen(pw_pattern), path) > 0
                       || (pattern != NULL
                           && match_prefix(pattern, strlen(pattern), path) > 0);
        }
        return 0;
}


static int
scan_directory(struct mg_connection *conn,
               const char *dir,
               void *data,
               void (*cb)(struct de *, void *))
{
        char path[PATH_MAX];
        struct dirent *dp;
        DIR *dirp;
        struct de de;
        int truncated;

        if ((dirp = mg_opendir(conn, dir)) == NULL) {
                return 0;
        } else {
                de.conn = conn;

                while ((dp = mg_readdir(dirp)) != NULL) {
                        /* Do not show current dir and hidden files */
                        if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, "..")
                            || must_hide_file(conn, dp->d_name)) {
                                continue;
                        }

                        mg_snprintf(
                            conn, &truncated, path, sizeof(path), "%s/%s", dir, dp->d_name);

                        /* If we don't memset stat structure to zero, mtime will have
                         * garbage and strftime() will segfault later on in
                         * print_dir_entry(). memset is required only if mg_stat()
                         * fails. For more details, see
                         * http://code.google.com/p/mongoose/issues/detail?id=79 */
                        memset(&de.file, 0, sizeof(de.file));

                        if (truncated) {
                                /* If the path is not complete, skip processing. */
                                continue;
                        }

                        if (!mg_stat(conn, path, &de.file)) {
                                mg_cry(conn,
                                       "%s: mg_stat(%s) failed: %s",
                                       __func__,
                                       path,
                                       strerror(ERRNO));
                        }
                        de.file_name = dp->d_name;
                        cb(&de, data);
                }
                (void)mg_closedir(dirp);
        }
        return 1;
}


#if !defined(NO_FILES)
static int
remove_directory(struct mg_connection *conn, const char *dir)
{
        char path[PATH_MAX];
        struct dirent *dp;
        DIR *dirp;
        struct de de;
        int truncated;
        int ok = 1;

        if ((dirp = mg_opendir(conn, dir)) == NULL) {
                return 0;
        } else {
                de.conn = conn;

                while ((dp = mg_readdir(dirp)) != NULL) {
                        /* Do not show current dir (but show hidden files as they will
                         * also be removed) */
                        if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, "..")) {
                                continue;
                        }

                        mg_snprintf(
                            conn, &truncated, path, sizeof(path), "%s/%s", dir, dp->d_name);

                        /* If we don't memset stat structure to zero, mtime will have
                         * garbage and strftime() will segfault later on in
                         * print_dir_entry(). memset is required only if mg_stat()
                         * fails. For more details, see
                         * http://code.google.com/p/mongoose/issues/detail?id=79 */
                        memset(&de.file, 0, sizeof(de.file));

                        if (truncated) {
                                /* Do not delete anything shorter */
                                ok = 0;
                                continue;
                        }

                        if (!mg_stat(conn, path, &de.file)) {
                                mg_cry(conn,
                                       "%s: mg_stat(%s) failed: %s",
                                       __func__,
                                       path,
                                       strerror(ERRNO));
                                ok = 0;
                        }
                        if (de.file.membuf == NULL) {
                                /* file is not in memory */
                                if (de.file.is_directory) {
                                        if (remove_directory(conn, path) == 0) {
                                                ok = 0;
                                        }
                                } else {
                                        if (mg_remove(conn, path) == 0) {
                                                ok = 0;
                                        }
                                }
                        } else {
                                /* file is in memory. It can not be deleted. */
                                ok = 0;
                        }
                }
                (void)mg_closedir(dirp);

                IGNORE_UNUSED_RESULT(rmdir(dir));
        }

        return ok;
}
#endif


struct dir_scan_data {
        struct de *entries;
        unsigned int num_entries;
        unsigned int arr_size;
};


/* Behaves like realloc(), but frees original pointer on failure */
static void *
realloc2(void *ptr, size_t size)
{
        void *new_ptr = mg_realloc(ptr, size);
        if (new_ptr == NULL) {
                mg_free(ptr);
        }
        return new_ptr;
}


static void
dir_scan_callback(struct de *de, void *data)
{
        struct dir_scan_data *dsd = (struct dir_scan_data *)data;

        if (dsd->entries == NULL || dsd->num_entries >= dsd->arr_size) {
                dsd->arr_size *= 2;
                dsd->entries =
                    (struct de *)realloc2(dsd->entries,
                                          dsd->arr_size * sizeof(dsd->entries[0]));
        }
        if (dsd->entries == NULL) {
                /* TODO(lsm, low): propagate an error to the caller */
                dsd->num_entries = 0;
        } else {
                dsd->entries[dsd->num_entries].file_name = mg_strdup(de->file_name);
                dsd->entries[dsd->num_entries].file = de->file;
                dsd->entries[dsd->num_entries].conn = de->conn;
                dsd->num_entries++;
        }
}


static void
handle_directory_request(struct mg_connection *conn, const char *dir)
{
        unsigned int i;
        int sort_direction;
        struct dir_scan_data data = {NULL, 0, 128};
        char date[64];
        time_t curtime = time(NULL);

        if (!scan_directory(conn, dir, &data, dir_scan_callback)) {
                send_http_error(conn,
                                500,
                                "Error: Cannot open directory\nopendir(%s): %s",
                                dir,
                                strerror(ERRNO));
                return;
        }

        gmt_time_string(date, sizeof(date), &curtime);

        if (!conn) {
                return;
        }

        sort_direction = conn->request_info.query_string != NULL
                                 && conn->request_info.query_string[1] == 'd'
                             ? 'a'
                             : 'd';

        conn->must_close = 1;
        mg_printf(conn, "HTTP/1.1 200 OK\r\n");
        send_static_cache_header(conn);
        mg_printf(conn,
                  "Date: %s\r\n"
                  "Connection: close\r\n"
                  "Content-Type: text/html; charset=utf-8\r\n\r\n",
                  date);

        conn->num_bytes_sent +=
            mg_printf(conn,
                      "<html><head><title>Index of %s</title>"
                      "<style>th {text-align: left;}</style></head>"
                      "<body><h1>Index of %s</h1><pre><table cellpadding=\"0\">"
                      "<tr><th><a href=\"?n%c\">Name</a></th>"
                      "<th><a href=\"?d%c\">Modified</a></th>"
                      "<th><a href=\"?s%c\">Size</a></th></tr>"
                      "<tr><td colspan=\"3\"><hr></td></tr>",
                      conn->request_info.local_uri,
                      conn->request_info.local_uri,
                      sort_direction,
                      sort_direction,
                      sort_direction);

        /* Print first entry - link to a parent directory */
        conn->num_bytes_sent +=
            mg_printf(conn,
                      "<tr><td><a href=\"%s%s\">%s</a></td>"
                      "<td>&nbsp;%s</td><td>&nbsp;&nbsp;%s</td></tr>\n",
                      conn->request_info.local_uri,
                      "..",
                      "Parent directory",
                      "-",
                      "-");

        /* Sort and print directory entries */
        if (data.entries != NULL) {
                qsort(data.entries,
                      (size_t)data.num_entries,
                      sizeof(data.entries[0]),
                      compare_dir_entries);
                for (i = 0; i < data.num_entries; i++) {
                        print_dir_entry(&data.entries[i]);
                        mg_free(data.entries[i].file_name);
                }
                mg_free(data.entries);
        }

        conn->num_bytes_sent += mg_printf(conn, "%s", "</table></body></html>");
        conn->status_code = 200;
}


/* Send len bytes from the opened file to the client. */
static void
send_file_data(struct mg_connection *conn,
               struct file *filep,
               int64_t offset,
               int64_t len)
{
        char buf[MG_BUF_LEN];
        int to_read, num_read, num_written;
        int64_t size;

        if (!filep || !conn) {
                return;
        }

        /* Sanity check the offset */
        size = filep->size > INT64_MAX ? INT64_MAX : (int64_t)(filep->size);
        offset = offset < 0 ? 0 : offset > size ? size : offset;

        if (len > 0 && filep->membuf != NULL && size > 0) {
                /* file stored in memory */
                if (len > size - offset) {
                        len = size - offset;
                }
                mg_write(conn, filep->membuf + offset, (size_t)len);
        } else if (len > 0 && filep->fp != NULL) {
/* file stored on disk */
#if defined(__linux__)
                /* sendfile is only available for Linux */
                if (conn->throttle == 0 && conn->ssl == 0) {
                        off_t sf_offs = (off_t)offset;
                        ssize_t sf_sent;
                        int sf_file = fileno(filep->fp);
                        int loop_cnt = 0;

                        do {
                                /* 2147479552 (0x7FFFF000) is a limit found by experiment on
                                 * 64 bit Linux (2^31 minus one memory page of 4k?). */
                                size_t sf_tosend =
                                    (size_t)((len < 0x7FFFF000) ? len : 0x7FFFF000);
                                sf_sent =
                                    sendfile(conn->client.sock, sf_file, &sf_offs, sf_tosend);
                                if (sf_sent > 0) {
                                        conn->num_bytes_sent += sf_sent;
                                        len -= sf_sent;
                                        offset += sf_sent;
                                } else if (loop_cnt == 0) {
                                        /* This file can not be sent using sendfile.
                                         * This might be the case for pseudo-files in the
                                         * /sys/ and /proc/ file system.
                                         * Use the regular user mode copy code instead. */
                                        break;
                                } else if (sf_sent == 0) {
                                        /* No error, but 0 bytes sent. May be EOF? */
                                        return;
                                }
                                loop_cnt++;

                        } while ((len > 0) && (sf_sent >= 0));

                        if (sf_sent > 0) {
                                return; /* OK */
                        }

                        /* sf_sent<0 means error, thus fall back to the classic way */
                        /* This is always the case, if sf_file is not a "normal" file,
                         * e.g., for sending data from the output of a CGI process. */
                        offset = (int64_t)sf_offs;
                }
#endif
                if ((offset > 0) && (fseeko(filep->fp, offset, SEEK_SET) != 0)) {
                        mg_cry(conn, "%s: fseeko() failed: %s", __func__, strerror(ERRNO));
                        send_http_error(
                            conn,
                            500,
                            "%s",
                            "Error: Unable to access file at requested position.");
                } else {
                        while (len > 0) {
                                /* Calculate how much to read from the file in the buffer */
                                to_read = sizeof(buf);
                                if ((int64_t)to_read > len) {
                                        to_read = (int)len;
                                }

                                /* Read from file, exit the loop on error */
                                if ((num_read = (int)fread(buf, 1, (size_t)to_read, filep->fp))
                                    <= 0) {
                                        break;
                                }

                                /* Send read bytes to the client, exit the loop on error */
                                if ((num_written = mg_write(conn, buf, (size_t)num_read))
                                    != num_read) {
                                        break;
                                }

                                /* Both read and were successful, adjust counters */
                                conn->num_bytes_sent += num_written;
                                len -= num_written;
                        }
                }
        }
}


static int
parse_range_header(const char *header, int64_t *a, int64_t *b)
{
        return sscanf(header, "bytes=%" INT64_FMT "-%" INT64_FMT, a, b);
}


static void
construct_etag(char *buf, size_t buf_len, const struct file *filep)
{
        if (filep != NULL && buf != NULL) {
                mg_snprintf(NULL,
                            NULL, /* All calls to construct_etag use 64 byte buffer */
                            buf,
                            buf_len,
                            "\"%lx.%" INT64_FMT "\"",
                            (unsigned long)filep->last_modified,
                            filep->size);
        }
}


static void
fclose_on_exec(struct file *filep, struct mg_connection *conn)
{
        if (filep != NULL && filep->fp != NULL) {
#ifdef _WIN32
                (void)conn; /* Unused. */
#else
                if (fcntl(fileno(filep->fp), F_SETFD, FD_CLOEXEC) != 0) {
                        mg_cry(conn,
                               "%s: fcntl(F_SETFD FD_CLOEXEC) failed: %s",
                               __func__,
                               strerror(ERRNO));
                }
#endif
        }
}


static void
handle_static_file_request(struct mg_connection *conn,
                           const char *path,
                           struct file *filep,
                           const char *mime_type)
{
        char date[64], lm[64], etag[64];
        char range[128]; /* large enough, so there will be no overflow */
        const char *msg = "OK", *hdr;
        time_t curtime = time(NULL);
        int64_t cl, r1, r2;
        struct vec mime_vec;
        int n, truncated;
        char gz_path[PATH_MAX];
        const char *encoding = "";
        const char *cors1, *cors2, *cors3;

        if (conn == NULL || conn->ctx == NULL || filep == NULL) {
                return;
        }

        if (mime_type == NULL) {
                get_mime_type(conn->ctx, path, &mime_vec);
        } else {
                mime_vec.ptr = mime_type;
                mime_vec.len = strlen(mime_type);
        }
        if (filep->size > INT64_MAX) {
                send_http_error(conn,
                                500,
                                "Error: File size is too large to send\n%" INT64_FMT,
                                filep->size);
        }
        cl = (int64_t)filep->size;
        conn->status_code = 200;
        range[0] = '\0';

        /* if this file is in fact a pre-gzipped file, rewrite its filename
         * it's important to rewrite the filename after resolving
         * the mime type from it, to preserve the actual file's type */
        if (filep->gzipped) {
                mg_snprintf(conn, &truncated, gz_path, sizeof(gz_path), "%s.gz", path);

                if (truncated) {
                        send_http_error(conn,
                                        500,
                                        "Error: Path of zipped file too long (%s)",
                                        path);
                        return;
                }

                path = gz_path;
                encoding = "Content-Encoding: gzip\r\n";
        }

        if (!mg_fopen(conn, path, "rb", filep)) {
                send_http_error(conn,
                                500,
                                "Error: Cannot open file\nfopen(%s): %s",
                                path,
                                strerror(ERRNO));
                return;
        }

        fclose_on_exec(filep, conn);

        /* If Range: header specified, act accordingly */
        r1 = r2 = 0;
        hdr = mg_get_header(conn, "Range");
        if (hdr != NULL && (n = parse_range_header(hdr, &r1, &r2)) > 0 && r1 >= 0
            && r2 >= 0) {
                /* actually, range requests don't play well with a pre-gzipped
                 * file (since the range is specified in the uncompressed space) */
                if (filep->gzipped) {
                        send_http_error(
                            conn,
                            501,
                            "%s",
                            "Error: Range requests in gzipped files are not supported");
                        mg_fclose(filep);
                        return;
                }
                conn->status_code = 206;
                cl = n == 2 ? (r2 > cl ? cl : r2) - r1 + 1 : cl - r1;
                mg_snprintf(conn,
                            NULL, /* range buffer is big enough */
                            range,
                            sizeof(range),
                            "Content-Range: bytes "
                            "%" INT64_FMT "-%" INT64_FMT "/%" INT64_FMT "\r\n",
                            r1,
                            r1 + cl - 1,
                            filep->size);
                msg = "Partial Content";
        }

        hdr = mg_get_header(conn, "Origin");
        if (hdr) {
                /* Cross-origin resource sharing (CORS), see
                 * http://www.html5rocks.com/en/tutorials/cors/,
                 * http://www.html5rocks.com/static/images/cors_server_flowchart.png -
                 * preflight is not supported for files. */
                cors1 = "Access-Control-Allow-Origin: ";
                cors2 = conn->ctx->config[ACCESS_CONTROL_ALLOW_ORIGIN];
                cors3 = "\r\n";
        } else {
                cors1 = cors2 = cors3 = "";
        }

        /* Prepare Etag, Date, Last-Modified headers. Must be in UTC, according to
         * http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3 */
        gmt_time_string(date, sizeof(date), &curtime);
        gmt_time_string(lm, sizeof(lm), &filep->last_modified);
        construct_etag(etag, sizeof(etag), filep);

        (void)mg_printf(conn,
                        "HTTP/1.1 %d %s\r\n"
                        "%s%s%s"
                        "Date: %s\r\n",
                        conn->status_code,
                        msg,
                        cors1,
                        cors2,
                        cors3,
                        date);
        send_static_cache_header(conn);
        (void)mg_printf(conn,
                        "Last-Modified: %s\r\n"
                        "Etag: %s\r\n"
                        "Content-Type: %.*s\r\n"
                        "Content-Length: %" INT64_FMT "\r\n"
                        "Connection: %s\r\n"
                        "Accept-Ranges: bytes\r\n"
                        "%s%s\r\n",
                        lm,
                        etag,
                        (int)mime_vec.len,
                        mime_vec.ptr,
                        cl,
                        suggest_connection_header(conn),
                        range,
                        encoding);

        if (strcmp(conn->request_info.request_method, "HEAD") != 0) {
                send_file_data(conn, filep, r1, cl);
        }
        mg_fclose(filep);
}


void
mg_send_file(struct mg_connection *conn, const char *path)
{
        mg_send_mime_file(conn, path, NULL);
}


void
mg_send_mime_file(struct mg_connection *conn,
                  const char *path,
                  const char *mime_type)
{
        struct file file = STRUCT_FILE_INITIALIZER;
        if (mg_stat(conn, path, &file)) {
                if (file.is_directory) {
                        if (!conn) {
                                return;
                        }
                        if (!mg_strcasecmp(conn->ctx->config[ENABLE_DIRECTORY_LISTING],
                                           "yes")) {
                                handle_directory_request(conn, path);
                        } else {
                                send_http_error(conn,
                                                403,
                                                "%s",
                                                "Error: Directory listing denied");
                        }
                } else {
                        handle_static_file_request(conn, path, &file, mime_type);
                }
        } else {
                send_http_error(conn, 404, "%s", "Error: File not found");
        }
}


/* For a given PUT path, create all intermediate subdirectories.
 * Return  0  if the path itself is a directory.
 * Return  1  if the path leads to a file.
 * Return -1  for if the path is too long.
 * Return -2  if path can not be created.
*/
static int
put_dir(struct mg_connection *conn, const char *path)
{
        char buf[PATH_MAX];
        const char *s, *p;
        struct file file = STRUCT_FILE_INITIALIZER;
        size_t len;
        int res = 1;

        for (s = p = path + 2; (p = strchr(s, '/')) != NULL; s = ++p) {
                len = (size_t)(p - path);
                if (len >= sizeof(buf)) {
                        /* path too long */
                        res = -1;
                        break;
                }
                memcpy(buf, path, len);
                buf[len] = '\0';

                /* Try to create intermediate directory */
                DEBUG_TRACE("mkdir(%s)", buf);
                if (!mg_stat(conn, buf, &file) && mg_mkdir(conn, buf, 0755) != 0) {
                        /* path does not exixt and can not be created */
                        res = -2;
                        break;
                }

                /* Is path itself a directory? */
                if (p[1] == '\0') {
                        res = 0;
                }
        }

        return res;
}


static void
remove_bad_file(const struct mg_connection *conn, const char *path)
{
        int r = mg_remove(conn, path);
        if (r != 0) {
                mg_cry(conn, "%s: Cannot remove invalid file %s", __func__, path);
        }
}


long long
mg_store_body(struct mg_connection *conn, const char *path)
{
        char buf[MG_BUF_LEN];
        long long len = 0;
        int ret, n;
        struct file fi;

        if (conn->consumed_content != 0) {
                mg_cry(conn, "%s: Contents already consumed", __func__);
                return -11;
        }

        ret = put_dir(conn, path);
        if (ret < 0) {
                /* -1 for path too long,
                 * -2 for path can not be created. */
                return ret;
        }
        if (ret != 1) {
                /* Return 0 means, path itself is a directory. */
                return 0;
        }

        if (mg_fopen(conn, path, "w", &fi) == 0) {
                return -12;
        }

        ret = mg_read(conn, buf, sizeof(buf));
        while (ret > 0) {
                n = (int)fwrite(buf, 1, (size_t)ret, fi.fp);
                if (n != ret) {
                        mg_fclose(&fi);
                        remove_bad_file(conn, path);
                        return -13;
                }
                ret = mg_read(conn, buf, sizeof(buf));
        }

        /* TODO: mg_fclose should return an error,
         * and every caller should check and handle it. */
        if (fclose(fi.fp) != 0) {
                remove_bad_file(conn, path);
                return -14;
        }

        return len;
}


/* Parse HTTP headers from the given buffer, advance buffer to the point
 * where parsing stopped. */
static void
parse_http_headers(char **buf, struct mg_request_info *ri)
{
        int i;

        if (!ri) {
                return;
        }

        ri->num_headers = 0;

        for (i = 0; i < (int)ARRAY_SIZE(ri->http_headers); i++) {
                char *dp = *buf;
                while ((*dp != ':') && (*dp != '\r') && (*dp != 0)) {
                        dp++;
                }
                if (!*dp) {
                        /* neither : nor \r\n. This is not a valid field. */
                        break;
                }
                if (*dp == '\r') {
                        if (dp[1] == '\n') {
                                /* \r\n */
                                ri->http_headers[i].name = *buf;
                                ri->http_headers[i].value = 0;
                                *buf = dp;
                        } else {
                                /* stray \r. This is not valid. */
                                break;
                        }
                } else {
                        /* (*dp == ':') */
                        *dp = 0;
                        ri->http_headers[i].name = *buf;
                        do {
                                dp++;
                        } while (*dp == ' ');

                        ri->http_headers[i].value = dp;
                        *buf = strstr(dp, "\r\n");
                }

                ri->num_headers = i + 1;
                if (*buf) {
                        (*buf)[0] = 0;
                        (*buf)[1] = 0;
                        *buf += 2;
                } else {
                        *buf = dp;
                        break;
                }

                if (*buf[0] == '\r') {
                        /* This is the end of the header */
                        break;
                }
        }
}


static int
is_valid_http_method(const char *method)
{
        return !strcmp(method, "GET")        /* HTTP (RFC 2616) */
               || !strcmp(method, "POST")    /* HTTP (RFC 2616) */
               || !strcmp(method, "HEAD")    /* HTTP (RFC 2616) */
               || !strcmp(method, "PUT")     /* HTTP (RFC 2616) */
               || !strcmp(method, "DELETE")  /* HTTP (RFC 2616) */
               || !strcmp(method, "OPTIONS") /* HTTP (RFC 2616) */
               /* TRACE method (RFC 2616) is not supported for security reasons */
               || !strcmp(method, "CONNECT") /* HTTP (RFC 2616) */

               || !strcmp(method, "PROPFIND") /* WEBDAV (RFC 2518) */
               || !strcmp(method, "MKCOL")    /* WEBDAV (RFC 2518) */

               /* Unsupported WEBDAV Methods: */
               /* PROPPATCH, COPY, MOVE, LOCK, UNLOCK (RFC 2518) */
               /* + 11 methods from RFC 3253 */
               /* ORDERPATCH (RFC 3648) */
               /* ACL (RFC 3744) */
               /* SEARCH (RFC 5323) */
               /* + MicroSoft extensions
                * https://msdn.microsoft.com/en-us/library/aa142917.aspx */

               /* PATCH method only allowed for CGI/Lua/LSP and callbacks. */
               || !strcmp(method, "PATCH"); /* PATCH method (RFC 5789) */
}


/* Parse HTTP request, fill in mg_request_info structure.
 * This function modifies the buffer by NUL-terminating
 * HTTP request components, header names and header values. */
static int
parse_http_message(int check_method,
                   char *buf,
                   int len,
                   struct mg_request_info *ri)
{
        int is_request, request_length;

        if (!ri) {
                return 0;
        }

        request_length = get_request_len(buf, len);

        if (request_length > 0) {
                /* Reset attributes. DO NOT TOUCH is_ssl, remote_ip, remote_addr,
                 * remote_port */
                ri->remote_user = ri->request_method = ri->request_uri =
                    ri->http_version = NULL;
                ri->num_headers = 0;

                buf[request_length - 1] = '\0';

                /* RFC says that all initial whitespaces should be ingored */
                while (*buf != '\0' && isspace(*(unsigned char *)buf)) {
                        buf++;
                }
                ri->request_method = skip(&buf, " ");
                ri->request_uri = skip(&buf, " ");
                ri->http_version = skip(&buf, "\r\n");

                /* HTTP message could be either HTTP request or HTTP response, e.g.
                 * "GET / HTTP/1.0 ...." or  "HTTP/1.0 200 OK ..." */
                is_request =
                    check_method ? is_valid_http_method(ri->request_method) : 1;
                if ((is_request && memcmp(ri->http_version, "HTTP/", 5) != 0)
                    || (!is_request && memcmp(ri->request_method, "HTTP/", 5) != 0)) {
                        request_length = -1;
                } else {
                        if (is_request) {
                                ri->http_version += 5;
                        }
                        parse_http_headers(&buf, ri);
                }
        }
        return request_length;
}


/* Keep reading the input (either opened file descriptor fd, or socket sock,
 * or SSL descriptor ssl) into buffer buf, until \r\n\r\n appears in the
 * buffer (which marks the end of HTTP request). Buffer buf may already
 * have some data. The length of the data is stored in nread.
 * Upon every read operation, increase nread by the number of bytes read. */
static int
read_request(FILE *fp,
             struct mg_connection *conn,
             char *buf,
             int bufsiz,
             int *nread)
{
        int request_len, n = 0;
        struct timespec last_action_time;
        double request_timeout;

        if (!conn) {
                return 0;
        }

        memset(&last_action_time, 0, sizeof(last_action_time));

        if (conn->ctx->config[REQUEST_TIMEOUT]) {
                /* value of request_timeout is in seconds, config in milliseconds */
                request_timeout = atof(conn->ctx->config[REQUEST_TIMEOUT]) / 1000.0;
        } else {
                request_timeout = -1.0;
        }

        request_len = get_request_len(buf, *nread);

        /* first time reading from this connection */
        clock_gettime(CLOCK_MONOTONIC, &last_action_time);

        while (
            (conn->ctx->stop_flag == 0) && (*nread < bufsiz) && (request_len == 0)
            && ((mg_difftimespec(&last_action_time, &(conn->req_time))
                 <= request_timeout) || (request_timeout < 0))
            && ((n = pull(fp, conn, buf + *nread, bufsiz - *nread, request_timeout))
                > 0)) {
                *nread += n;
                /* assert(*nread <= bufsiz); */
                if (*nread > bufsiz) {
                        return -2;
                }
                request_len = get_request_len(buf, *nread);
                if (request_timeout > 0.0) {
                        clock_gettime(CLOCK_MONOTONIC, &last_action_time);
                }
        }

        return (request_len <= 0 && n <= 0) ? -1 : request_len;
}

#if !defined(NO_FILES)
/* For given directory path, substitute it to valid index file.
 * Return 1 if index file has been found, 0 if not found.
 * If the file is found, it's stats is returned in stp. */
static int
substitute_index_file(struct mg_connection *conn,
                      char *path,
                      size_t path_len,
                      struct file *filep)
{
        if (conn && conn->ctx) {
                const char *list = conn->ctx->config[INDEX_FILES];
                struct file file = STRUCT_FILE_INITIALIZER;
                struct vec filename_vec;
                size_t n = strlen(path);
                int found = 0;

                /* The 'path' given to us points to the directory. Remove all trailing
                 * directory separator characters from the end of the path, and
                 * then append single directory separator character. */
                while (n > 0 && path[n - 1] == '/') {
                        n--;
                }
                path[n] = '/';

                /* Traverse index files list. For each entry, append it to the given
                 * path and see if the file exists. If it exists, break the loop */
                while ((list = next_option(list, &filename_vec, NULL)) != NULL) {
                        /* Ignore too long entries that may overflow path buffer */
                        if (filename_vec.len > path_len - (n + 2)) {
                                continue;
                        }

                        /* Prepare full path to the index file */
                        mg_strlcpy(path + n + 1, filename_vec.ptr, filename_vec.len + 1);

                        /* Does it exist? */
                        if (mg_stat(conn, path, &file)) {
                                /* Yes it does, break the loop */
                                *filep = file;
                                found = 1;
                                break;
                        }
                }

                /* If no index file exists, restore directory path */
                if (!found) {
                        path[n] = '\0';
                }

                return found;
        }
        return 0;
}
#endif


#if !defined(NO_CACHING)
/* Return True if we should reply 304 Not Modified. */
static int
is_not_modified(const struct mg_connection *conn, const struct file *filep)
{
        char etag[64];
        const char *ims = mg_get_header(conn, "If-Modified-Since");
        const char *inm = mg_get_header(conn, "If-None-Match");
        construct_etag(etag, sizeof(etag), filep);
        if (!filep) {
                return 0;
        }
        return (inm != NULL && !mg_strcasecmp(etag, inm))
               || (ims != NULL && (filep->last_modified <= parse_date_string(ims)));
}
#endif /* !NO_CACHING */


#if !defined(NO_CGI) || !defined(NO_FILES)
static int
forward_body_data(struct mg_connection *conn, FILE *fp, SOCKET sock, SSL *ssl)
{
        const char *expect, *body;
        char buf[MG_BUF_LEN];
        int to_read, nread, success = 0;
        int64_t buffered_len;
        double timeout = -1.0;

        if (!conn) {
                return 0;
        }
        if (conn->ctx->config[REQUEST_TIMEOUT]) {
                timeout = atoi(conn->ctx->config[REQUEST_TIMEOUT]) / 1000.0;
        }

        expect = mg_get_header(conn, "Expect");
        /* assert(fp != NULL); */
        if (!fp) {
                send_http_error(conn, 500, "%s", "Error: NULL File");
                return 0;
        }

        if (conn->content_len == -1 && !conn->is_chunked) {
                /* Content length is not specified by the client. */
                send_http_error(conn,
                                411,
                                "%s",
                                "Error: Client did not specify content length");
        } else if ((expect != NULL)
                   && (mg_strcasecmp(expect, "100-continue") != 0)) {
                /* Client sent an "Expect: xyz" header and xyz is not 100-continue. */
                send_http_error(conn,
                                417,
                                "Error: Can not fulfill expectation %s",
                                expect);
        } else {
                if (expect != NULL) {
                        (void)mg_printf(conn, "%s", "HTTP/1.1 100 Continue\r\n\r\n");
                        conn->status_code = 100;
                } else {
                        conn->status_code = 200;
                }

                buffered_len = (int64_t)(conn->data_len) - (int64_t)conn->request_len
                               - conn->consumed_content;

                /* assert(buffered_len >= 0); */
                /* assert(conn->consumed_content == 0); */

                if ((buffered_len < 0) || (conn->consumed_content != 0)) {
                        send_http_error(conn, 500, "%s", "Error: Size mismatch");
                        return 0;
                }

                if (buffered_len > 0) {
                        if ((int64_t)buffered_len > conn->content_len) {
                                buffered_len = (int)conn->content_len;
                        }
                        body = conn->buf + conn->request_len + conn->consumed_content;
                        push_all(conn->ctx, fp, sock, ssl, body, (int64_t)buffered_len);
                        conn->consumed_content += buffered_len;
                }

                nread = 0;
                while (conn->consumed_content < conn->content_len) {
                        to_read = sizeof(buf);
                        if ((int64_t)to_read > conn->content_len - conn->consumed_content) {
                                to_read = (int)(conn->content_len - conn->consumed_content);
                        }
                        nread = pull(NULL, conn, buf, to_read, timeout);
                        if (nread <= 0
                            || push_all(conn->ctx, fp, sock, ssl, buf, nread) != nread) {
                                break;
                        }
                        conn->consumed_content += nread;
                }

                if (conn->consumed_content == conn->content_len) {
                        success = (nread >= 0);
                }

                /* Each error code path in this function must send an error */
                if (!success) {
                        /* NOTE: Maybe some data has already been sent. */
                        /* TODO (low): If some data has been sent, a correct error
                         * reply can no longer be sent, so just close the connection */
                        send_http_error(conn, 500, "%s", "");
                }
        }

        return success;
}
#endif

#if !defined(NO_CGI)
/* This structure helps to create an environment for the spawned CGI program.
 * Environment is an array of "VARIABLE=VALUE\0" ASCIIZ strings,
 * last element must be NULL.
 * However, on Windows there is a requirement that all these VARIABLE=VALUE\0
 * strings must reside in a contiguous buffer. The end of the buffer is
 * marked by two '\0' characters.
 * We satisfy both worlds: we create an envp array (which is vars), all
 * entries are actually pointers inside buf. */
struct cgi_environment {
        struct mg_connection *conn;
        /* Data block */
        char *buf;      /* Environment buffer */
        size_t buflen;  /* Space available in buf */
        size_t bufused; /* Space taken in buf */
                        /* Index block */
        char **var;     /* char **envp */
        size_t varlen;  /* Number of variables available in var */
        size_t varused; /* Number of variables stored in var */
};


static void addenv(struct cgi_environment *env,
                   PRINTF_FORMAT_STRING(const char *fmt),
                   ...) PRINTF_ARGS(2, 3);

/* Append VARIABLE=VALUE\0 string to the buffer, and add a respective
 * pointer into the vars array. Assumes env != NULL and fmt != NULL. */
static void
addenv(struct cgi_environment *env, const char *fmt, ...)
{
        size_t n, space;
        int truncated;
        char *added;
        va_list ap;

        /* Calculate how much space is left in the buffer */
        space = (env->buflen - env->bufused);

        /* Calculate an estimate for the required space */
        n = strlen(fmt) + 2 + 128;

        do {
                if (space <= n) {
                        /* Allocate new buffer */
                        n = env->buflen + CGI_ENVIRONMENT_SIZE;
                        added = (char *)mg_realloc(env->buf, n);
                        if (!added) {
                                /* Out of memory */
                                mg_cry(env->conn,
                                       "%s: Cannot allocate memory for CGI variable [%s]",
                                       __func__,
                                       fmt);
                                return;
                        }
                        env->buf = added;
                        env->buflen = n;
                        space = (env->buflen - env->bufused);
                }

                /* Make a pointer to the free space int the buffer */
                added = env->buf + env->bufused;

                /* Copy VARIABLE=VALUE\0 string into the free space */
                va_start(ap, fmt);
                mg_vsnprintf(env->conn, &truncated, added, (size_t)space, fmt, ap);
                va_end(ap);

                /* Do not add truncated strings to the environment */
                if (truncated) {
                        /* Reallocate the buffer */
                        space = 0;
                        n = 1;
                }
        } while (truncated);

        /* Calculate number of bytes added to the environment */
        n = strlen(added) + 1;
        env->bufused += n;

        /* Now update the variable index */
        space = (env->varlen - env->varused);
        if (space < 2) {
                mg_cry(env->conn,
                       "%s: Cannot register CGI variable [%s]",
                       __func__,
                       fmt);
                return;
        }

        /* Append a pointer to the added string into the envp array */
        env->var[env->varused] = added;
        env->varused++;
}


static void
prepare_cgi_environment(struct mg_connection *conn,
                        const char *prog,
                        struct cgi_environment *env)
{
        const char *s;
        struct vec var_vec;
        char *p, src_addr[IP_ADDR_STR_LEN], http_var_name[128];
        int i, truncated;

        if (conn == NULL || prog == NULL || env == NULL) {
                return;
        }

        env->conn = conn;
        env->buflen = CGI_ENVIRONMENT_SIZE;
        env->bufused = 0;
        env->buf = (char *)mg_malloc(env->buflen);
        env->varlen = MAX_CGI_ENVIR_VARS;
        env->varused = 0;
        env->var = (char **)mg_malloc(env->buflen * sizeof(char *));

        addenv(env, "SERVER_NAME=%s", conn->ctx->config[AUTHENTICATION_DOMAIN]);
        addenv(env, "SERVER_ROOT=%s", conn->ctx->config[DOCUMENT_ROOT]);
        addenv(env, "DOCUMENT_ROOT=%s", conn->ctx->config[DOCUMENT_ROOT]);
        addenv(env, "SERVER_SOFTWARE=%s/%s", "Civetweb", mg_version());

        /* Prepare the environment block */
        addenv(env, "%s", "GATEWAY_INTERFACE=CGI/1.1");
        addenv(env, "%s", "SERVER_PROTOCOL=HTTP/1.1");
        addenv(env, "%s", "REDIRECT_STATUS=200"); /* For PHP */

#if defined(USE_IPV6)
        if (conn->client.lsa.sa.sa_family == AF_INET6) {
                addenv(env, "SERVER_PORT=%d", ntohs(conn->client.lsa.sin6.sin6_port));
        } else
#endif
        {
                addenv(env, "SERVER_PORT=%d", ntohs(conn->client.lsa.sin.sin_port));
        }

        sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);
        addenv(env, "REMOTE_ADDR=%s", src_addr);

        addenv(env, "REQUEST_METHOD=%s", conn->request_info.request_method);
        addenv(env, "REMOTE_PORT=%d", conn->request_info.remote_port);

        addenv(env, "REQUEST_URI=%s", conn->request_info.request_uri);
        addenv(env, "LOCAL_URI=%s", conn->request_info.local_uri);

        /* SCRIPT_NAME */
        addenv(env,
               "SCRIPT_NAME=%.*s",
               (int)strlen(conn->request_info.local_uri)
                   - ((conn->path_info == NULL) ? 0 : (int)strlen(conn->path_info)),
               conn->request_info.local_uri);

        addenv(env, "SCRIPT_FILENAME=%s", prog);
        if (conn->path_info == NULL) {
                addenv(env, "PATH_TRANSLATED=%s", conn->ctx->config[DOCUMENT_ROOT]);
        } else {
                addenv(env,
                       "PATH_TRANSLATED=%s%s",
                       conn->ctx->config[DOCUMENT_ROOT],
                       conn->path_info);
        }

        addenv(env, "HTTPS=%s", conn->ssl == NULL ? "off" : "on");

        if ((s = mg_get_header(conn, "Content-Type")) != NULL) {
                addenv(env, "CONTENT_TYPE=%s", s);
        }
        if (conn->request_info.query_string != NULL) {
                addenv(env, "QUERY_STRING=%s", conn->request_info.query_string);
        }
        if ((s = mg_get_header(conn, "Content-Length")) != NULL) {
                addenv(env, "CONTENT_LENGTH=%s", s);
        }
        if ((s = getenv("PATH")) != NULL) {
                addenv(env, "PATH=%s", s);
        }
        if (conn->path_info != NULL) {
                addenv(env, "PATH_INFO=%s", conn->path_info);
        }

        if (conn->status_code > 0) {
                /* CGI error handler should show the status code */
                addenv(env, "STATUS=%d", conn->status_code);
        }

#if defined(_WIN32)
        if ((s = getenv("COMSPEC")) != NULL) {
                addenv(env, "COMSPEC=%s", s);
        }
        if ((s = getenv("SYSTEMROOT")) != NULL) {
                addenv(env, "SYSTEMROOT=%s", s);
        }
        if ((s = getenv("SystemDrive")) != NULL) {
                addenv(env, "SystemDrive=%s", s);
        }
        if ((s = getenv("ProgramFiles")) != NULL) {
                addenv(env, "ProgramFiles=%s", s);
        }
        if ((s = getenv("ProgramFiles(x86)")) != NULL) {
                addenv(env, "ProgramFiles(x86)=%s", s);
        }
#else
        if ((s = getenv("LD_LIBRARY_PATH")) != NULL) {
                addenv(env, "LD_LIBRARY_PATH=%s", s);
        }
#endif /* _WIN32 */

        if ((s = getenv("PERLLIB")) != NULL) {
                addenv(env, "PERLLIB=%s", s);
        }

        if (conn->request_info.remote_user != NULL) {
                addenv(env, "REMOTE_USER=%s", conn->request_info.remote_user);
                addenv(env, "%s", "AUTH_TYPE=Digest");
        }

        /* Add all headers as HTTP_* variables */
        for (i = 0; i < conn->request_info.num_headers; i++) {

                (void)mg_snprintf(conn,
                                  &truncated,
                                  http_var_name,
                                  sizeof(http_var_name),
                                  "HTTP_%s",
                                  conn->request_info.http_headers[i].name);

                if (truncated) {
                        mg_cry(conn,
                               "%s: HTTP header variable too long [%s]",
                               __func__,
                               conn->request_info.http_headers[i].name);
                        continue;
                }

                /* Convert variable name into uppercase, and change - to _ */
                for (p = http_var_name; *p != '\0'; p++) {
                        if (*p == '-') {
                                *p = '_';
                        }
                        *p = (char)toupper(*(unsigned char *)p);
                }

                addenv(env,
                       "%s=%s",
                       http_var_name,
                       conn->request_info.http_headers[i].value);
        }

        /* Add user-specified variables */
        s = conn->ctx->config[CGI_ENVIRONMENT];
        while ((s = next_option(s, &var_vec, NULL)) != NULL) {
                addenv(env, "%.*s", (int)var_vec.len, var_vec.ptr);
        }

        env->var[env->varused] = NULL;
        env->buf[env->bufused] = '\0';
}


static void
handle_cgi_request(struct mg_connection *conn, const char *prog)
{
        char *buf;
        size_t buflen;
        int headers_len, data_len, i, truncated;
        int fdin[2] = {-1, -1}, fdout[2] = {-1, -1}, fderr[2] = {-1, -1};
        const char *status, *status_text, *connection_state;
        char *pbuf, dir[PATH_MAX], *p;
        struct mg_request_info ri;
        struct cgi_environment blk;
        FILE *in = NULL, *out = NULL, *err = NULL;
        struct file fout = STRUCT_FILE_INITIALIZER;
        pid_t pid = (pid_t)-1;

        if (conn == NULL) {
                return;
        }

        buf = NULL;
        buflen = 16384;
        prepare_cgi_environment(conn, prog, &blk);

        /* CGI must be executed in its own directory. 'dir' must point to the
         * directory containing executable program, 'p' must point to the
         * executable program name relative to 'dir'. */
        (void)mg_snprintf(conn, &truncated, dir, sizeof(dir), "%s", prog);

        if (truncated) {
                mg_cry(conn, "Error: CGI program \"%s\": Path too long", prog);
                send_http_error(conn, 500, "Error: %s", "CGI path too long");
                goto done;
        }

        if ((p = strrchr(dir, '/')) != NULL) {
                *p++ = '\0';
        } else {
                dir[0] = '.', dir[1] = '\0';
                p = (char *)prog;
        }

        if (pipe(fdin) != 0 || pipe(fdout) != 0 || pipe(fderr) != 0) {
                status = strerror(ERRNO);
                mg_cry(conn,
                       "Error: CGI program \"%s\": Can not create CGI pipes: %s",
                       prog,
                       status);
                send_http_error(conn, 500, "Error: Cannot create CGI pipe: %s", status);
                goto done;
        }

        pid = spawn_process(conn, p, blk.buf, blk.var, fdin, fdout, fderr, dir);

        if (pid == (pid_t)-1) {
                status = strerror(ERRNO);
                mg_cry(conn,
                       "Error: CGI program \"%s\": Can not spawn CGI process: %s",
                       prog,
                       status);
                send_http_error(conn,
                                500,
                                "Error: Cannot spawn CGI process [%s]: %s",
                                prog,
                                status);
                goto done;
        }

        /* Make sure child closes all pipe descriptors. It must dup them to 0,1 */
        set_close_on_exec((SOCKET)fdin[0], conn);  /* stdin read */
        set_close_on_exec((SOCKET)fdout[1], conn); /* stdout write */
        set_close_on_exec((SOCKET)fderr[1], conn); /* stderr write */
        set_close_on_exec((SOCKET)fdin[1], conn);  /* stdin write */
        set_close_on_exec((SOCKET)fdout[0], conn); /* stdout read */
        set_close_on_exec((SOCKET)fderr[0], conn); /* stderr read */

        /* Parent closes only one side of the pipes.
         * If we don't mark them as closed, close() attempt before
         * return from this function throws an exception on Windows.
         * Windows does not like when closed descriptor is closed again. */
        (void)close(fdin[0]);
        (void)close(fdout[1]);
        (void)close(fderr[1]);
        fdin[0] = fdout[1] = fderr[1] = -1;

        if ((in = fdopen(fdin[1], "wb")) == NULL) {
                status = strerror(ERRNO);
                mg_cry(conn,
                       "Error: CGI program \"%s\": Can not open stdin: %s",
                       prog,
                       status);
                send_http_error(conn,
                                500,
                                "Error: CGI can not open fdin\nfopen: %s",
                                status);
                goto done;
        }

        if ((out = fdopen(fdout[0], "rb")) == NULL) {
                status = strerror(ERRNO);
                mg_cry(conn,
                       "Error: CGI program \"%s\": Can not open stdout: %s",
                       prog,
                       status);
                send_http_error(conn,
                                500,
                                "Error: CGI can not open fdout\nfopen: %s",
                                status);
                goto done;
        }

        if ((err = fdopen(fderr[0], "rb")) == NULL) {
                status = strerror(ERRNO);
                mg_cry(conn,
                       "Error: CGI program \"%s\": Can not open stderr: %s",
                       prog,
                       status);
                send_http_error(conn,
                                500,
                                "Error: CGI can not open fdout\nfopen: %s",
                                status);
                goto done;
        }

        setbuf(in, NULL);
        setbuf(out, NULL);
        setbuf(err, NULL);
        fout.fp = out;

        if ((conn->request_info.content_length > 0) || conn->is_chunked) {
                /* This is a POST/PUT request, or another request with body data. */
                if (!forward_body_data(conn, in, INVALID_SOCKET, NULL)) {
                        /* Error sending the body data */
                        mg_cry(conn,
                               "Error: CGI program \"%s\": Forward body data failed",
                               prog);
                        goto done;
                }
        }

        /* Close so child gets an EOF. */
        fclose(in);
        in = NULL;
        fdin[1] = -1;

        /* Now read CGI reply into a buffer. We need to set correct
         * status code, thus we need to see all HTTP headers first.
         * Do not send anything back to client, until we buffer in all
         * HTTP headers. */
        data_len = 0;
        buf = (char *)mg_malloc(buflen);
        if (buf == NULL) {
                send_http_error(conn,
                                500,
                                "Error: Not enough memory for CGI buffer (%u bytes)",
                                (unsigned int)buflen);
                mg_cry(conn,
                       "Error: CGI program \"%s\": Not enough memory for buffer (%u "
                       "bytes)",
                       prog,
                       (unsigned int)buflen);
                goto done;
        }
        headers_len = read_request(out, conn, buf, (int)buflen, &data_len);
        if (headers_len <= 0) {

                /* Could not parse the CGI response. Check if some error message on
                 * stderr. */
                i = pull_all(err, conn, buf, (int)buflen);
                if (i > 0) {
                        mg_cry(conn,
                               "Error: CGI program \"%s\" sent error "
                               "message: [%.*s]",
                               prog,
                               i,
                               buf);
                        send_http_error(conn,
                                        500,
                                        "Error: CGI program \"%s\" sent error "
                                        "message: [%.*s]",
                                        prog,
                                        i,
                                        buf);
                } else {
                        mg_cry(conn,
                               "Error: CGI program sent malformed or too big "
                               "(>%u bytes) HTTP headers: [%.*s]",
                               (unsigned)buflen,
                               data_len,
                               buf);

                        send_http_error(conn,
                                        500,
                                        "Error: CGI program sent malformed or too big "
                                        "(>%u bytes) HTTP headers: [%.*s]",
                                        (unsigned)buflen,
                                        data_len,
                                        buf);
                }

                goto done;
        }
        pbuf = buf;
        buf[headers_len - 1] = '\0';
        parse_http_headers(&pbuf, &ri);

        /* Make up and send the status line */
        status_text = "OK";
        if ((status = get_header(&ri, "Status")) != NULL) {
                conn->status_code = atoi(status);
                status_text = status;
                while (isdigit(*(const unsigned char *)status_text)
                       || *status_text == ' ') {
                        status_text++;
                }
        } else if (get_header(&ri, "Location") != NULL) {
                conn->status_code = 302;
        } else {
                conn->status_code = 200;
        }
        connection_state = get_header(&ri, "Connection");
        if (!header_has_option(connection_state, "keep-alive")) {
                conn->must_close = 1;
        }
        (void)mg_printf(conn, "HTTP/1.1 %d %s\r\n", conn->status_code, status_text);

        /* Send headers */
        for (i = 0; i < ri.num_headers; i++) {
                mg_printf(conn,
                          "%s: %s\r\n",
                          ri.http_headers[i].name,
                          ri.http_headers[i].value);
        }
        mg_write(conn, "\r\n", 2);

        /* Send chunk of data that may have been read after the headers */
        conn->num_bytes_sent +=
            mg_write(conn, buf + headers_len, (size_t)(data_len - headers_len));

        /* Read the rest of CGI output and send to the client */
        send_file_data(conn, &fout, 0, INT64_MAX);

done:
        mg_free(blk.var);
        mg_free(blk.buf);

        if (pid != (pid_t)-1) {
                kill(pid, SIGKILL);
#if !defined(_WIN32)
                {
                        int st;
                        while (waitpid(pid, &st, 0) != -1)
                                ; /* clean zombies */
                }
#endif
        }
        if (fdin[0] != -1) {
                close(fdin[0]);
        }
        if (fdout[1] != -1) {
                close(fdout[1]);
        }

        if (in != NULL) {
                fclose(in);
        } else if (fdin[1] != -1) {
                close(fdin[1]);
        }

        if (out != NULL) {
                fclose(out);
        } else if (fdout[0] != -1) {
                close(fdout[0]);
        }

        if (err != NULL) {
                fclose(err);
        } else if (fderr[0] != -1) {
                close(fderr[0]);
        }

        if (buf != NULL) {
                mg_free(buf);
        }
}
#endif /* !NO_CGI */


#if !defined(NO_FILES)
static void
mkcol(struct mg_connection *conn, const char *path)
{
        int rc, body_len;
        struct de de;
        char date[64];
        time_t curtime = time(NULL);

        if (conn == NULL) {
                return;
        }

        /* TODO (mid): Check the send_http_error situations in this function */

        memset(&de.file, 0, sizeof(de.file));
        if (!mg_stat(conn, path, &de.file)) {
                mg_cry(conn,
                       "%s: mg_stat(%s) failed: %s",
                       __func__,
                       path,
                       strerror(ERRNO));
        }

        if (de.file.last_modified) {
                /* TODO (high): This check does not seem to make any sense ! */
                send_http_error(
                    conn, 405, "Error: mkcol(%s): %s", path, strerror(ERRNO));
                return;
        }

        body_len = conn->data_len - conn->request_len;
        if (body_len > 0) {
                send_http_error(
                    conn, 415, "Error: mkcol(%s): %s", path, strerror(ERRNO));
                return;
        }

        rc = mg_mkdir(conn, path, 0755);

        if (rc == 0) {
                conn->status_code = 201;
                gmt_time_string(date, sizeof(date), &curtime);
                mg_printf(conn,
                          "HTTP/1.1 %d Created\r\n"
                          "Date: %s\r\n",
                          conn->status_code,
                          date);
                send_static_cache_header(conn);
                mg_printf(conn,
                          "Content-Length: 0\r\n"
                          "Connection: %s\r\n\r\n",
                          suggest_connection_header(conn));
        } else if (rc == -1) {
                if (errno == EEXIST) {
                        send_http_error(
                            conn, 405, "Error: mkcol(%s): %s", path, strerror(ERRNO));
                } else if (errno == EACCES) {
                        send_http_error(
                            conn, 403, "Error: mkcol(%s): %s", path, strerror(ERRNO));
                } else if (errno == ENOENT) {
                        send_http_error(
                            conn, 409, "Error: mkcol(%s): %s", path, strerror(ERRNO));
                } else {
                        send_http_error(conn, 500, "fopen(%s): %s", path, strerror(ERRNO));
                }
        }
}


static void
put_file(struct mg_connection *conn, const char *path)
{
        struct file file = STRUCT_FILE_INITIALIZER;
        const char *range;
        int64_t r1, r2;
        int rc;
        char date[64];
        time_t curtime = time(NULL);

        if (conn == NULL) {
                return;
        }

        if (mg_stat(conn, path, &file)) {
                /* File already exists */
                conn->status_code = 200;

                if (file.is_directory) {
                        /* This is an already existing directory,
                         * so there is nothing to do for the server. */
                        rc = 0;

                } else {
                        /* File exists and is not a directory. */
                        /* Can it be replaced? */

                        if (file.membuf != NULL) {
                                /* This is an "in-memory" file, that can not be replaced */
                                send_http_error(
                                    conn,
                                    405,
                                    "Error: Put not possible\nReplacing %s is not supported",
                                    path);
                                return;
                        }

                        /* Check if the server may write this file */
                        if (access(path, W_OK) == 0) {
                                /* Access granted */
                                conn->status_code = 200;
                                rc = 1;
                        } else {
                                send_http_error(
                                    conn,
                                    403,
                                    "Error: Put not possible\nReplacing %s is not allowed",
                                    path);
                                return;
                        }
                }
        } else {
                /* File should be created */
                conn->status_code = 201;
                rc = put_dir(conn, path);
        }

        if (rc == 0) {
                /* put_dir returns 0 if path is a directory */
                gmt_time_string(date, sizeof(date), &curtime);
                mg_printf(conn,
                          "HTTP/1.1 %d %s\r\n",
                          conn->status_code,
                          mg_get_response_code_text(NULL, conn->status_code));
                send_no_cache_header(conn);
                mg_printf(conn,
                          "Date: %s\r\n"
                          "Content-Length: 0\r\n"
                          "Connection: %s\r\n\r\n",
                          date,
                          suggest_connection_header(conn));

                /* Request to create a directory has been fulfilled successfully.
                 * No need to put a file. */
                return;
        }

        if (rc == -1) {
                /* put_dir returns -1 if the path is too long */
                send_http_error(conn,
                                414,
                                "Error: Path too long\nput_dir(%s): %s",
                                path,
                                strerror(ERRNO));
                return;
        }

        if (rc == -2) {
                /* put_dir returns -2 if the directory can not be created */
                send_http_error(conn,
                                500,
                                "Error: Can not create directory\nput_dir(%s): %s",
                                path,
                                strerror(ERRNO));
                return;
        }

        /* A file should be created or overwritten. */
        if (!mg_fopen(conn, path, "wb+", &file) || file.fp == NULL) {
                mg_fclose(&file);
                send_http_error(conn,
                                500,
                                "Error: Can not create file\nfopen(%s): %s",
                                path,
                                strerror(ERRNO));
                return;
        }

        fclose_on_exec(&file, conn);
        range = mg_get_header(conn, "Content-Range");
        r1 = r2 = 0;
        if (range != NULL && parse_range_header(range, &r1, &r2) > 0) {
                conn->status_code = 206; /* Partial content */
                fseeko(file.fp, r1, SEEK_SET);
        }

        if (!forward_body_data(conn, file.fp, INVALID_SOCKET, NULL)) {
                /* forward_body_data failed.
                 * The error code has already been sent to the client,
                 * and conn->status_code is already set. */
                mg_fclose(&file);
                return;
        }

        gmt_time_string(date, sizeof(date), &curtime);
        mg_printf(conn,
                  "HTTP/1.1 %d %s\r\n",
                  conn->status_code,
                  mg_get_response_code_text(NULL, conn->status_code));
        send_no_cache_header(conn);
        mg_printf(conn,
                  "Date: %s\r\n"
                  "Content-Length: 0\r\n"
                  "Connection: %s\r\n\r\n",
                  date,
                  suggest_connection_header(conn));

        mg_fclose(&file);
}


static void
delete_file(struct mg_connection *conn, const char *path)
{
        struct de de;
        memset(&de.file, 0, sizeof(de.file));
        if (!mg_stat(conn, path, &de.file)) {
                /* mg_stat returns 0 if the file does not exist */
                send_http_error(conn,
                                404,
                                "Error: Cannot delete file\nFile %s not found",
                                path);
                return;
        }

        if (de.file.membuf != NULL) {
                /* the file is cached in memory */
                send_http_error(
                    conn,
                    405,
                    "Error: Delete not possible\nDeleting %s is not supported",
                    path);
                return;
        }

        if (de.file.is_directory) {
                if (remove_directory(conn, path)) {
                        /* Delete is successful: Return 204 without content. */
                        send_http_error(conn, 204, "%s", "");
                } else {
                        /* Delete is not successful: Return 500 (Server error). */
                        send_http_error(conn, 500, "Error: Could not delete %s", path);
                }
                return;
        }

        /* This is an existing file (not a directory).
         * Check if write permission is granted. */
        if (access(path, W_OK) != 0) {
                /* File is read only */
                send_http_error(
                    conn,
                    403,
                    "Error: Delete not possible\nDeleting %s is not allowed",
                    path);
                return;
        }

        /* Try to delete it. */
        if (mg_remove(conn, path) == 0) {
                /* Delete was successful: Return 204 without content. */
                send_http_error(conn, 204, "%s", "");
        } else {
                /* Delete not successful (file locked). */
                send_http_error(conn,
                                423,
                                "Error: Cannot delete file\nremove(%s): %s",
                                path,
                                strerror(ERRNO));
        }
}
#endif /* !NO_FILES */


static void
send_ssi_file(struct mg_connection *, const char *, struct file *, int);


static void
do_ssi_include(struct mg_connection *conn,
               const char *ssi,
               char *tag,
               int include_level)
{
        char file_name[MG_BUF_LEN], path[512], *p;
        struct file file = STRUCT_FILE_INITIALIZER;
        size_t len;
        int truncated = 0;

        if (conn == NULL) {
                return;
        }

        /* sscanf() is safe here, since send_ssi_file() also uses buffer
         * of size MG_BUF_LEN to get the tag. So strlen(tag) is
         * always < MG_BUF_LEN. */
        if (sscanf(tag, " virtual=\"%511[^\"]\"", file_name) == 1) {
                /* File name is relative to the webserver root */
                file_name[511] = 0;
                (void)mg_snprintf(conn,
                                  &truncated,
                                  path,
                                  sizeof(path),
                                  "%s/%s",
                                  conn->ctx->config[DOCUMENT_ROOT],
                                  file_name);

        } else if (sscanf(tag, " abspath=\"%511[^\"]\"", file_name) == 1) {
                /* File name is relative to the webserver working directory
                 * or it is absolute system path */
                file_name[511] = 0;
                (void)
                    mg_snprintf(conn, &truncated, path, sizeof(path), "%s", file_name);

        } else if (sscanf(tag, " file=\"%511[^\"]\"", file_name) == 1
                   || sscanf(tag, " \"%511[^\"]\"", file_name) == 1) {
                /* File name is relative to the currect document */
                file_name[511] = 0;
                (void)mg_snprintf(conn, &truncated, path, sizeof(path), "%s", ssi);

                if (!truncated) {
                        if ((p = strrchr(path, '/')) != NULL) {
                                p[1] = '\0';
                        }
                        len = strlen(path);
                        (void)mg_snprintf(conn,
                                          &truncated,
                                          path + len,
                                          sizeof(path) - len,
                                          "%s",
                                          file_name);
                }

        } else {
                mg_cry(conn, "Bad SSI #include: [%s]", tag);
                return;
        }

        if (truncated) {
                mg_cry(conn, "SSI #include path length overflow: [%s]", tag);
                return;
        }

        if (!mg_fopen(conn, path, "rb", &file)) {
                mg_cry(conn,
                       "Cannot open SSI #include: [%s]: fopen(%s): %s",
                       tag,
                       path,
                       strerror(ERRNO));
        } else {
                fclose_on_exec(&file, conn);
                if (match_prefix(conn->ctx->config[SSI_EXTENSIONS],
                                 strlen(conn->ctx->config[SSI_EXTENSIONS]),
                                 path) > 0) {
                        send_ssi_file(conn, path, &file, include_level + 1);
                } else {
                        send_file_data(conn, &file, 0, INT64_MAX);
                }
                mg_fclose(&file);
        }
}


#if !defined(NO_POPEN)
static void
do_ssi_exec(struct mg_connection *conn, char *tag)
{
        char cmd[1024] = "";
        struct file file = STRUCT_FILE_INITIALIZER;

        if (sscanf(tag, " \"%1023[^\"]\"", cmd) != 1) {
                mg_cry(conn, "Bad SSI #exec: [%s]", tag);
        } else {
                cmd[1023] = 0;
                if ((file.fp = popen(cmd, "r")) == NULL) {
                        mg_cry(conn, "Cannot SSI #exec: [%s]: %s", cmd, strerror(ERRNO));
                } else {
                        send_file_data(conn, &file, 0, INT64_MAX);
                        pclose(file.fp);
                }
        }
}
#endif /* !NO_POPEN */


static int
mg_fgetc(struct file *filep, int offset)
{
        if (filep == NULL) {
                return EOF;
        }
        if (filep->membuf != NULL && offset >= 0
            && ((unsigned int)(offset)) < filep->size) {
                return ((const unsigned char *)filep->membuf)[offset];
        } else if (filep->fp != NULL) {
                return fgetc(filep->fp);
        } else {
                return EOF;
        }
}


static void
send_ssi_file(struct mg_connection *conn,
              const char *path,
              struct file *filep,
              int include_level)
{
        char buf[MG_BUF_LEN];
        int ch, offset, len, in_ssi_tag;

        if (include_level > 10) {
                mg_cry(conn, "SSI #include level is too deep (%s)", path);
                return;
        }

        in_ssi_tag = len = offset = 0;
        while ((ch = mg_fgetc(filep, offset)) != EOF) {
                if (in_ssi_tag && ch == '>') {
                        in_ssi_tag = 0;
                        buf[len++] = (char)ch;
                        buf[len] = '\0';
                        /* assert(len <= (int) sizeof(buf)); */
                        if (len > (int)sizeof(buf)) {
                                break;
                        }
                        if (len < 6 || memcmp(buf, "<!--#", 5) != 0) {
                                /* Not an SSI tag, pass it */
                                (void)mg_write(conn, buf, (size_t)len);
                        } else {
                                if (!memcmp(buf + 5, "include", 7)) {
                                        do_ssi_include(conn, path, buf + 12, include_level);
#if !defined(NO_POPEN)
                                } else if (!memcmp(buf + 5, "exec", 4)) {
                                        do_ssi_exec(conn, buf + 9);
#endif /* !NO_POPEN */
                                } else {
                                        mg_cry(conn,
                                               "%s: unknown SSI "
                                               "command: \"%s\"",
                                               path,
                                               buf);
                                }
                        }
                        len = 0;
                } else if (in_ssi_tag) {
                        if (len == 5 && memcmp(buf, "<!--#", 5) != 0) {
                                /* Not an SSI tag */
                                in_ssi_tag = 0;
                        } else if (len == (int)sizeof(buf) - 2) {
                                mg_cry(conn, "%s: SSI tag is too large", path);
                                len = 0;
                        }
                        buf[len++] = (char)(ch & 0xff);
                } else if (ch == '<') {
                        in_ssi_tag = 1;
                        if (len > 0) {
                                mg_write(conn, buf, (size_t)len);
                        }
                        len = 0;
                        buf[len++] = (char)(ch & 0xff);
                } else {
                        buf[len++] = (char)(ch & 0xff);
                        if (len == (int)sizeof(buf)) {
                                mg_write(conn, buf, (size_t)len);
                                len = 0;
                        }
                }
        }

        /* Send the rest of buffered data */
        if (len > 0) {
                mg_write(conn, buf, (size_t)len);
        }
}


static void
handle_ssi_file_request(struct mg_connection *conn,
                        const char *path,
                        struct file *filep)
{
        char date[64];
        time_t curtime = time(NULL);
        const char *cors1, *cors2, *cors3;

        if (conn == NULL || path == NULL || filep == NULL) {
                return;
        }

        if (mg_get_header(conn, "Origin")) {
                /* Cross-origin resource sharing (CORS). */
                cors1 = "Access-Control-Allow-Origin: ";
                cors2 = conn->ctx->config[ACCESS_CONTROL_ALLOW_ORIGIN];
                cors3 = "\r\n";
        } else {
                cors1 = cors2 = cors3 = "";
        }

        if (!mg_fopen(conn, path, "rb", filep)) {
                /* File exists (precondition for calling this function),
                 * but can not be opened by the server. */
                send_http_error(conn,
                                500,
                                "Error: Cannot read file\nfopen(%s): %s",
                                path,
                                strerror(ERRNO));
        } else {
                conn->must_close = 1;
                gmt_time_string(date, sizeof(date), &curtime);
                fclose_on_exec(filep, conn);
                mg_printf(conn, "HTTP/1.1 200 OK\r\n");
                send_no_cache_header(conn);
                mg_printf(conn,
                          "%s%s%s"
                          "Date: %s\r\n"
                          "Content-Type: text/html\r\n"
                          "Connection: %s\r\n\r\n",
                          cors1,
                          cors2,
                          cors3,
                          date,
                          suggest_connection_header(conn));
                send_ssi_file(conn, path, filep, 0);
                mg_fclose(filep);
        }
}


#if !defined(NO_FILES)
static void
send_options(struct mg_connection *conn)
{
        char date[64];
        time_t curtime = time(NULL);

        if (!conn) {
                return;
        }

        conn->status_code = 200;
        conn->must_close = 1;
        gmt_time_string(date, sizeof(date), &curtime);

        mg_printf(conn,
                  "HTTP/1.1 200 OK\r\n"
                  "Date: %s\r\n"
                  /* TODO: "Cache-Control" (?) */
                  "Connection: %s\r\n"
                  "Allow: GET, POST, HEAD, CONNECT, PUT, DELETE, OPTIONS, "
                  "PROPFIND, MKCOL\r\n"
                  "DAV: 1\r\n\r\n",
                  date,
                  suggest_connection_header(conn));
}


/* Writes PROPFIND properties for a collection element */
static void
print_props(struct mg_connection *conn, const char *uri, struct file *filep)
{
        char mtime[64];

        if (conn == NULL || uri == NULL || filep == NULL) {
                return;
        }

        gmt_time_string(mtime, sizeof(mtime), &filep->last_modified);
        conn->num_bytes_sent +=
            mg_printf(conn,
                      "<d:response>"
                      "<d:href>%s</d:href>"
                      "<d:propstat>"
                      "<d:prop>"
                      "<d:resourcetype>%s</d:resourcetype>"
                      "<d:getcontentlength>%" INT64_FMT "</d:getcontentlength>"
                      "<d:getlastmodified>%s</d:getlastmodified>"
                      "</d:prop>"
                      "<d:status>HTTP/1.1 200 OK</d:status>"
                      "</d:propstat>"
                      "</d:response>\n",
                      uri,
                      filep->is_directory ? "<d:collection/>" : "",
                      filep->size,
                      mtime);
}


static void
print_dav_dir_entry(struct de *de, void *data)
{
        char href[PATH_MAX];
        char href_encoded[PATH_MAX];
        int truncated;

        struct mg_connection *conn = (struct mg_connection *)data;
        if (!de || !conn) {
                return;
        }
        mg_snprintf(conn,
                    &truncated,
                    href,
                    sizeof(href),
                    "%s%s",
                    conn->request_info.local_uri,
                    de->file_name);

        if (!truncated) {
                mg_url_encode(href, href_encoded, PATH_MAX - 1);
                print_props(conn, href_encoded, &de->file);
        }
}


static void
handle_propfind(struct mg_connection *conn,
                const char *path,
                struct file *filep)
{
        const char *depth = mg_get_header(conn, "Depth");
        char date[64];
        time_t curtime = time(NULL);

        gmt_time_string(date, sizeof(date), &curtime);

        if (!conn || !path || !filep || !conn->ctx) {
                return;
        }

        conn->must_close = 1;
        conn->status_code = 207;
        mg_printf(conn,
                  "HTTP/1.1 207 Multi-Status\r\n"
                  "Date: %s\r\n",
                  date);
        send_static_cache_header(conn);
        mg_printf(conn,
                  "Connection: %s\r\n"
                  "Content-Type: text/xml; charset=utf-8\r\n\r\n",
                  suggest_connection_header(conn));

        conn->num_bytes_sent +=
            mg_printf(conn,
                      "<?xml version=\"1.0\" encoding=\"utf-8\"?>"
                      "<d:multistatus xmlns:d='DAV:'>\n");

        /* Print properties for the requested resource itself */
        print_props(conn, conn->request_info.local_uri, filep);

        /* If it is a directory, print directory entries too if Depth is not 0 */
        if (filep && filep->is_directory
            && !mg_strcasecmp(conn->ctx->config[ENABLE_DIRECTORY_LISTING], "yes")
            && (depth == NULL || strcmp(depth, "0") != 0)) {
                scan_directory(conn, path, conn, &print_dav_dir_entry);
        }

        conn->num_bytes_sent += mg_printf(conn, "%s\n", "</d:multistatus>");
}
#endif

void
mg_lock_connection(struct mg_connection *conn)
{
        if (conn) {
                (void)pthread_mutex_lock(&conn->mutex);
        }
}

void
mg_unlock_connection(struct mg_connection *conn)
{
        if (conn) {
                (void)pthread_mutex_unlock(&conn->mutex);
        }
}

void
mg_lock_context(struct mg_context *ctx)
{
        if (ctx) {
                (void)pthread_mutex_lock(&ctx->nonce_mutex);
        }
}

void
mg_unlock_context(struct mg_context *ctx)
{
        if (ctx) {
                (void)pthread_mutex_unlock(&ctx->nonce_mutex);
        }
}

#if defined(USE_TIMERS)
#include "timer.inl"
#endif /* USE_TIMERS */

#ifdef USE_LUA
#include "mod_lua.inl"
#endif /* USE_LUA */

#ifdef USE_DUKTAPE
#include "mod_duktape.inl"
#endif /* USE_DUKTAPE */

#if defined(USE_WEBSOCKET)

/* START OF SHA-1 code
 * Copyright(c) By Steve Reid <steve@edmweb.com> */
#define SHA1HANDSOFF

/* According to current tests (May 2015), the <solarisfixes.h> is not required.
 *
 * #if defined(__sun)
 * #include "solarisfixes.h"
 * #endif
 */


static int
is_big_endian(void)
{
        static const int n = 1;
        return ((char *)&n)[0] == 0;
}


union char64long16 {
        unsigned char c[64];
        uint32_t l[16];
};

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))


static uint32_t
blk0(union char64long16 *block, int i)
{
        /* Forrest: SHA expect BIG_ENDIAN, swap if LITTLE_ENDIAN */
        if (!is_big_endian()) {
                block->l[i] = (rol(block->l[i], 24) & 0xFF00FF00)
                              | (rol(block->l[i], 8) & 0x00FF00FF);
        }
        return block->l[i];
}

#define blk(i)                                                                 \
        (block->l[i & 15] = rol(block->l[(i + 13) & 15] ^ block->l[(i + 8) & 15]   \
                                    ^ block->l[(i + 2) & 15] ^ block->l[i & 15],   \
                                1))
#define R0(v, w, x, y, z, i)                                                   \
        z += ((w & (x ^ y)) ^ y) + blk0(block, i) + 0x5A827999 + rol(v, 5);        \
        w = rol(w, 30);
#define R1(v, w, x, y, z, i)                                                   \
        z += ((w & (x ^ y)) ^ y) + blk(i) + 0x5A827999 + rol(v, 5);                \
        w = rol(w, 30);
#define R2(v, w, x, y, z, i)                                                   \
        z += (w ^ x ^ y) + blk(i) + 0x6ED9EBA1 + rol(v, 5);                        \
        w = rol(w, 30);
#define R3(v, w, x, y, z, i)                                                   \
        z += (((w | x) & y) | (w & x)) + blk(i) + 0x8F1BBCDC + rol(v, 5);          \
        w = rol(w, 30);
#define R4(v, w, x, y, z, i)                                                   \
        z += (w ^ x ^ y) + blk(i) + 0xCA62C1D6 + rol(v, 5);                        \
        w = rol(w, 30);


typedef struct {
        uint32_t state[5];
        uint32_t count[2];
        unsigned char buffer[64];
} SHA1_CTX;


static void
SHA1Transform(uint32_t state[5], const unsigned char buffer[64])
{
        uint32_t a, b, c, d, e;
        union char64long16 block[1];

        memcpy(block, buffer, 64);
        a = state[0];
        b = state[1];
        c = state[2];
        d = state[3];
        e = state[4];
        R0(a, b, c, d, e, 0);
        R0(e, a, b, c, d, 1);
        R0(d, e, a, b, c, 2);
        R0(c, d, e, a, b, 3);
        R0(b, c, d, e, a, 4);
        R0(a, b, c, d, e, 5);
        R0(e, a, b, c, d, 6);
        R0(d, e, a, b, c, 7);
        R0(c, d, e, a, b, 8);
        R0(b, c, d, e, a, 9);
        R0(a, b, c, d, e, 10);
        R0(e, a, b, c, d, 11);
        R0(d, e, a, b, c, 12);
        R0(c, d, e, a, b, 13);
        R0(b, c, d, e, a, 14);
        R0(a, b, c, d, e, 15);
        R1(e, a, b, c, d, 16);
        R1(d, e, a, b, c, 17);
        R1(c, d, e, a, b, 18);
        R1(b, c, d, e, a, 19);
        R2(a, b, c, d, e, 20);
        R2(e, a, b, c, d, 21);
        R2(d, e, a, b, c, 22);
        R2(c, d, e, a, b, 23);
        R2(b, c, d, e, a, 24);
        R2(a, b, c, d, e, 25);
        R2(e, a, b, c, d, 26);
        R2(d, e, a, b, c, 27);
        R2(c, d, e, a, b, 28);
        R2(b, c, d, e, a, 29);
        R2(a, b, c, d, e, 30);
        R2(e, a, b, c, d, 31);
        R2(d, e, a, b, c, 32);
        R2(c, d, e, a, b, 33);
        R2(b, c, d, e, a, 34);
        R2(a, b, c, d, e, 35);
        R2(e, a, b, c, d, 36);
        R2(d, e, a, b, c, 37);
        R2(c, d, e, a, b, 38);
        R2(b, c, d, e, a, 39);
        R3(a, b, c, d, e, 40);
        R3(e, a, b, c, d, 41);
        R3(d, e, a, b, c, 42);
        R3(c, d, e, a, b, 43);
        R3(b, c, d, e, a, 44);
        R3(a, b, c, d, e, 45);
        R3(e, a, b, c, d, 46);
        R3(d, e, a, b, c, 47);
        R3(c, d, e, a, b, 48);
        R3(b, c, d, e, a, 49);
        R3(a, b, c, d, e, 50);
        R3(e, a, b, c, d, 51);
        R3(d, e, a, b, c, 52);
        R3(c, d, e, a, b, 53);
        R3(b, c, d, e, a, 54);
        R3(a, b, c, d, e, 55);
        R3(e, a, b, c, d, 56);
        R3(d, e, a, b, c, 57);
        R3(c, d, e, a, b, 58);
        R3(b, c, d, e, a, 59);
        R4(a, b, c, d, e, 60);
        R4(e, a, b, c, d, 61);
        R4(d, e, a, b, c, 62);
        R4(c, d, e, a, b, 63);
        R4(b, c, d, e, a, 64);
        R4(a, b, c, d, e, 65);
        R4(e, a, b, c, d, 66);
        R4(d, e, a, b, c, 67);
        R4(c, d, e, a, b, 68);
        R4(b, c, d, e, a, 69);
        R4(a, b, c, d, e, 70);
        R4(e, a, b, c, d, 71);
        R4(d, e, a, b, c, 72);
        R4(c, d, e, a, b, 73);
        R4(b, c, d, e, a, 74);
        R4(a, b, c, d, e, 75);
        R4(e, a, b, c, d, 76);
        R4(d, e, a, b, c, 77);
        R4(c, d, e, a, b, 78);
        R4(b, c, d, e, a, 79);
        state[0] += a;
        state[1] += b;
        state[2] += c;
        state[3] += d;
        state[4] += e;
        a = b = c = d = e = 0;
        memset(block, '\0', sizeof(block));
}


static void
SHA1Init(SHA1_CTX *context)
{
        context->state[0] = 0x67452301;
        context->state[1] = 0xEFCDAB89;
        context->state[2] = 0x98BADCFE;
        context->state[3] = 0x10325476;
        context->state[4] = 0xC3D2E1F0;
        context->count[0] = context->count[1] = 0;
}


static void
SHA1Update(SHA1_CTX *context, const unsigned char *data, uint32_t len)
{
        uint32_t i, j;

        j = context->count[0];
        if ((context->count[0] += len << 3) < j) {
                context->count[1]++;
        }
        context->count[1] += (len >> 29);
        j = (j >> 3) & 63;
        if ((j + len) > 63) {
                memcpy(&context->buffer[j], data, (i = 64 - j));
                SHA1Transform(context->state, context->buffer);
                for (; i + 63 < len; i += 64) {
                        SHA1Transform(context->state, &data[i]);
                }
                j = 0;
        } else
                i = 0;
        memcpy(&context->buffer[j], &data[i], len - i);
}


static void
SHA1Final(unsigned char digest[20], SHA1_CTX *context)
{
        unsigned i;
        unsigned char finalcount[8], c;

        for (i = 0; i < 8; i++) {
                finalcount[i] = (unsigned char)((context->count[(i >= 4 ? 0 : 1)]
                                                 >> ((3 - (i & 3)) * 8)) & 255);
        }
        c = 0200;
        SHA1Update(context, &c, 1);
        while ((context->count[0] & 504) != 448) {
                c = 0000;
                SHA1Update(context, &c, 1);
        }
        SHA1Update(context, finalcount, 8);
        for (i = 0; i < 20; i++) {
                digest[i] = (unsigned char)((context->state[i >> 2]
                                             >> ((3 - (i & 3)) * 8)) & 255);
        }
        memset(context, '\0', sizeof(*context));
        memset(&finalcount, '\0', sizeof(finalcount));
}
/* END OF SHA1 CODE */


static int
send_websocket_handshake(struct mg_connection *conn, const char *websock_key)
{
        static const char *magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
        const char *protocol = NULL;
        char buf[100], sha[20], b64_sha[sizeof(sha) * 2];
        SHA1_CTX sha_ctx;
        int truncated;

        /* Calculate Sec-WebSocket-Accept reply from Sec-WebSocket-Key. */
        mg_snprintf(conn, &truncated, buf, sizeof(buf), "%s%s", websock_key, magic);
        if (truncated) {
                conn->must_close = 1;
                return 0;
        }

        SHA1Init(&sha_ctx);
        SHA1Update(&sha_ctx, (unsigned char *)buf, (uint32_t)strlen(buf));
        SHA1Final((unsigned char *)sha, &sha_ctx);
        base64_encode((unsigned char *)sha, sizeof(sha), b64_sha);
        mg_printf(conn,
                  "HTTP/1.1 101 Switching Protocols\r\n"
                  "Upgrade: websocket\r\n"
                  "Connection: Upgrade\r\n"
                  "Sec-WebSocket-Accept: %s\r\n",
                  b64_sha);
        protocol = mg_get_header(conn, "Sec-WebSocket-Protocol");
        if (protocol) {
                /* The protocol is a comma seperated list of names. */
                /* The server must only return one value from this list. */
                /* First check if it is a list or just a single value. */
                const char *sep = strchr(protocol, ',');
                if (sep == NULL) {
                        /* Just a single protocol -> accept it. */
                        mg_printf(conn, "Sec-WebSocket-Protocol: %s\r\n\r\n", protocol);
                } else {
                        /* Multiple protocols -> accept the first one. */
                        /* This is just a quick fix if the client offers multiple
                         * protocols. In order to get the behavior intended by
                         * RFC 6455 (https://tools.ietf.org/rfc/rfc6455.txt), it is
                         * required to have a list of websocket subprotocols accepted
                         * by the server. Then the server must either select a subprotocol
                         * supported by client and server, or the server has to abort the
                         * handshake by not returning a Sec-Websocket-Protocol header if
                         * no subprotocol is acceptable.
                         */
                        mg_printf(conn,
                                  "Sec-WebSocket-Protocol: %.*s\r\n\r\n",
                                  (int)(sep - protocol),
                                  protocol);
                }
                /* TODO: Real subprotocol negotiation instead of just taking the first
                 * websocket subprotocol suggested by the client. */
        } else {
                mg_printf(conn, "%s", "\r\n");
        }

        return 1;
}


static void
read_websocket(struct mg_connection *conn,
               mg_websocket_data_handler ws_data_handler,
               void *callback_data)
{
        /* Pointer to the beginning of the portion of the incoming websocket
         * message queue.
         * The original websocket upgrade request is never removed, so the queue
         * begins after it. */
        unsigned char *buf = (unsigned char *)conn->buf + conn->request_len;
        int n, error, exit_by_callback;

        /* body_len is the length of the entire queue in bytes
         * len is the length of the current message
         * data_len is the length of the current message's data payload
         * header_len is the length of the current message's header */
        size_t i, len, mask_len = 0, data_len = 0, header_len, body_len;

        /* "The masking key is a 32-bit value chosen at random by the client."
         * http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-17#section-5
        */
        unsigned char mask[4];

        /* data points to the place where the message is stored when passed to
         * the
         * websocket_data callback.  This is either mem on the stack, or a
         * dynamically allocated buffer if it is too large. */
        char mem[4096];
        char *data = mem;
        unsigned char mop; /* mask flag and opcode */
        double timeout = -1.0;

        if (conn->ctx->config[WEBSOCKET_TIMEOUT]) {
                timeout = atoi(conn->ctx->config[WEBSOCKET_TIMEOUT]) / 1000.0;
        }
        if ((timeout <= 0.0) && (conn->ctx->config[REQUEST_TIMEOUT])) {
                timeout = atoi(conn->ctx->config[REQUEST_TIMEOUT]) / 1000.0;
        }

        mg_set_thread_name("wsock");

        /* Loop continuously, reading messages from the socket, invoking the
         * callback, and waiting repeatedly until an error occurs. */
        while (!conn->ctx->stop_flag) {
                header_len = 0;
                assert(conn->data_len >= conn->request_len);
                if ((body_len = (size_t)(conn->data_len - conn->request_len)) >= 2) {
                        len = buf[1] & 127;
                        mask_len = buf[1] & 128 ? 4 : 0;
                        if (len < 126 && body_len >= mask_len) {
                                data_len = len;
                                header_len = 2 + mask_len;
                        } else if (len == 126 && body_len >= 4 + mask_len) {
                                header_len = 4 + mask_len;
                                data_len = ((((size_t)buf[2]) << 8) + buf[3]);
                        } else if (body_len >= 10 + mask_len) {
                                header_len = 10 + mask_len;
                                data_len = (((uint64_t)ntohl(*(uint32_t *)(void *)&buf[2]))
                                            << 32) + ntohl(*(uint32_t *)(void *)&buf[6]);
                        }
                }

                if (header_len > 0 && body_len >= header_len) {
                        /* Allocate space to hold websocket payload */
                        data = mem;
                        if (data_len > sizeof(mem)) {
                                data = (char *)mg_malloc(data_len);
                                if (data == NULL) {
                                        /* Allocation failed, exit the loop and then close the
                                         * connection */
                                        mg_cry(conn, "websocket out of memory; closing connection");
                                        break;
                                }
                        }

                        /* Copy the mask before we shift the queue and destroy it */
                        if (mask_len > 0) {
                                memcpy(mask, buf + header_len - mask_len, sizeof(mask));
                        } else {
                                memset(mask, 0, sizeof(mask));
                        }

                        /* Read frame payload from the first message in the queue into
                         * data and advance the queue by moving the memory in place. */
                        assert(body_len >= header_len);
                        if (data_len + header_len > body_len) {
                                mop = buf[0]; /* current mask and opcode */
                                /* Overflow case */
                                len = body_len - header_len;
                                memcpy(data, buf + header_len, len);
                                error = 0;
                                while (len < data_len) {
                                        n = pull(
                                            NULL, conn, data + len, (int)(data_len - len), timeout);
                                        if (n <= 0) {
                                                error = 1;
                                                break;
                                        }
                                        len += (size_t)n;
                                }
                                if (error) {
                                        mg_cry(conn, "Websocket pull failed; closing connection");
                                        break;
                                }
                                conn->data_len = conn->request_len;
                        } else {
                                mop = buf[0]; /* current mask and opcode, overwritten by
                                               * memmove() */
                                /* Length of the message being read at the front of the
                                 * queue */
                                len = data_len + header_len;

                                /* Copy the data payload into the data pointer for the
                                 * callback */
                                memcpy(data, buf + header_len, data_len);

                                /* Move the queue forward len bytes */
                                memmove(buf, buf + len, body_len - len);

                                /* Mark the queue as advanced */
                                conn->data_len -= (int)len;
                        }

                        /* Apply mask if necessary */
                        if (mask_len > 0) {
                                for (i = 0; i < data_len; ++i) {
                                        data[i] ^= mask[i & 3];
                                }
                        }

                        /* Exit the loop if callback signals to exit (server side),
                         * or "connection close" opcode received (client side). */
                        exit_by_callback = 0;
                        if ((ws_data_handler != NULL)
                            && !ws_data_handler(conn, mop, data, data_len, callback_data)) {
                                exit_by_callback = 1;
                        }

                        if (data != mem) {
                                mg_free(data);
                        }

                        if (exit_by_callback
                            || ((mop & 0xf) == WEBSOCKET_OPCODE_CONNECTION_CLOSE)) {
                                /* Opcode == 8, connection close */
                                break;
                        }

                        /* Not breaking the loop, process next websocket frame. */
                } else {
                        /* Read from the socket into the next available location in the
                         * message queue. */
                        if ((n = pull(NULL,
                                      conn,
                                      conn->buf + conn->data_len,
                                      conn->buf_size - conn->data_len,
                                      timeout)) <= 0) {
                                /* Error, no bytes read */
                                break;
                        }
                        conn->data_len += n;
                }
        }

        mg_set_thread_name("worker");
}


static int
mg_websocket_write_exec(struct mg_connection *conn,
                        int opcode,
                        const char *data,
                        size_t dataLen,
                        uint32_t masking_key)
{
        unsigned char header[14];
        size_t headerLen = 1;

        int retval = -1;

        header[0] = 0x80 + (opcode & 0xF);

        /* Frame format: http://tools.ietf.org/html/rfc6455#section-5.2 */
        if (dataLen < 126) {
                /* inline 7-bit length field */
                header[1] = (unsigned char)dataLen;
                headerLen = 2;
        } else if (dataLen <= 0xFFFF) {
                /* 16-bit length field */
                header[1] = 126;
                *(uint16_t *)(void *)(header + 2) = htons((uint16_t)dataLen);
                headerLen = 4;
        } else {
                /* 64-bit length field */
                header[1] = 127;
                *(uint32_t *)(void *)(header + 2) = htonl((uint64_t)dataLen >> 32);
                *(uint32_t *)(void *)(header + 6) = htonl(dataLen & 0xFFFFFFFF);
                headerLen = 10;
        }

        if (masking_key) {
                /* add mask */
                header[1] |= 0x80;
                *(uint32_t *)(void *)(header + headerLen) = masking_key;
                headerLen += 4;
        }


        /* Note that POSIX/Winsock's send() is threadsafe
         * http://stackoverflow.com/questions/1981372/are-parallel-calls-to-send-recv-on-the-same-socket-valid
         * but mongoose's mg_printf/mg_write is not (because of the loop in
         * push(), although that is only a problem if the packet is large or
         * outgoing buffer is full). */
        (void)mg_lock_connection(conn);
        retval = mg_write(conn, header, headerLen);
        if (dataLen > 0) {
                retval = mg_write(conn, data, dataLen);
        }
        mg_unlock_connection(conn);

        return retval;
}

int
mg_websocket_write(struct mg_connection *conn,
                   int opcode,
                   const char *data,
                   size_t dataLen)
{
        return mg_websocket_write_exec(conn, opcode, data, dataLen, 0);
}


static void
mask_data(const char *in, size_t in_len, uint32_t masking_key, char *out)
{
        size_t i = 0;

        i = 0;
        if ((in_len > 3) && ((ptrdiff_t)in % 4) == 0) {
                /* Convert in 32 bit words, if data is 4 byte aligned */
                while (i < (in_len - 3)) {
                        *(uint32_t *)(void *)(out + i) =
                            *(uint32_t *)(void *)(in + i) ^ masking_key;
                        i += 4;
                }
        }
        if (i != in_len) {
                /* convert 1-3 remaining bytes if ((dataLen % 4) != 0)*/
                while (i < in_len) {
                        *(uint8_t *)(void *)(out + i) =
                            *(uint8_t *)(void *)(in + i)
                            ^ *(((uint8_t *)&masking_key) + (i % 4));
                        i++;
                }
        }
}


int
mg_websocket_client_write(struct mg_connection *conn,
                          int opcode,
                          const char *data,
                          size_t dataLen)
{
        int retval = -1;
        char *masked_data = (char *)mg_malloc(((dataLen + 7) / 4) * 4);
        uint32_t masking_key = (uint32_t)get_random();

        if (masked_data == NULL) {
                /* Return -1 in an error case */
                mg_cry(conn,
                       "Cannot allocate buffer for masked websocket response: "
                       "Out of memory");
                return -1;
        }

        mask_data(data, dataLen, masking_key, masked_data);

        retval = mg_websocket_write_exec(
            conn, opcode, masked_data, dataLen, masking_key);
        mg_free(masked_data);

        return retval;
}


static void
handle_websocket_request(struct mg_connection *conn,
                         const char *path,
                         int is_callback_resource,
                         mg_websocket_connect_handler ws_connect_handler,
                         mg_websocket_ready_handler ws_ready_handler,
                         mg_websocket_data_handler ws_data_handler,
                         mg_websocket_close_handler ws_close_handler,
                         void *cbData)
{
        const char *websock_key = mg_get_header(conn, "Sec-WebSocket-Key");
        const char *version = mg_get_header(conn, "Sec-WebSocket-Version");
        int lua_websock = 0;

#if !defined(USE_LUA)
        (void)path;
#endif

        /* Step 1: Check websocket protocol version. */
        /* Step 1.1: Check Sec-WebSocket-Key. */
        if (!websock_key) {
                /* The RFC standard version (https://tools.ietf.org/html/rfc6455)
                 * requires a Sec-WebSocket-Key header.
                 */
                /* It could be the hixie draft version
                 * (http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-76).
                 */
                const char *key1 = mg_get_header(conn, "Sec-WebSocket-Key1");
                const char *key2 = mg_get_header(conn, "Sec-WebSocket-Key2");
                char key3[8];

                if ((key1 != NULL) && (key2 != NULL)) {
                        /* This version uses 8 byte body data in a GET request */
                        conn->content_len = 8;
                        if (8 == mg_read(conn, key3, 8)) {
                                /* This is the hixie version */
                                send_http_error(conn,
                                                426,
                                                "%s",
                                                "Protocol upgrade to RFC 6455 required");
                                return;
                        }
                }
                /* This is an unknown version */
                send_http_error(conn, 400, "%s", "Malformed websocket request");
                return;
        }

        /* Step 1.2: Check websocket protocol version. */
        /* The RFC version (https://tools.ietf.org/html/rfc6455) is 13. */
        if (version == NULL || strcmp(version, "13") != 0) {
                /* Reject wrong versions */
                send_http_error(conn, 426, "%s", "Protocol upgrade required");
                return;
        }

        /* Step 1.3: Could check for "Host", but we do not really nead this
         * value for anything, so just ignore it. */

        /* Step 2: If a callback is responsible, call it. */
        if (is_callback_resource) {
                if (ws_connect_handler != NULL
                    && ws_connect_handler(conn, cbData) != 0) {
                        /* C callback has returned non-zero, do not proceed with
                         * handshake.
                         */
                        /* Note that C callbacks are no longer called when Lua is
                         * responsible, so C can no longer filter callbacks for Lua. */
                        return;
                }
        }
#if defined(USE_LUA)
        /* Step 3: No callback. Check if Lua is responsible. */
        else {
                /* Step 3.1: Check if Lua is responsible. */
                if (conn->ctx->config[LUA_WEBSOCKET_EXTENSIONS]) {
                        lua_websock =
                            match_prefix(conn->ctx->config[LUA_WEBSOCKET_EXTENSIONS],
                                         strlen(
                                             conn->ctx->config[LUA_WEBSOCKET_EXTENSIONS]),
                                         path);
                }

                if (lua_websock) {
                        /* Step 3.2: Lua is responsible: call it. */
                        conn->lua_websocket_state = lua_websocket_new(path, conn);
                        if (!conn->lua_websocket_state) {
                                /* Lua rejected the new client */
                                return;
                        }
                }
        }
#endif

        /* Step 4: Check if there is a responsible websocket handler. */
        if (!is_callback_resource && !lua_websock) {
                /* There is no callback, an Lua is not responsible either. */
                /* Reply with a 404 Not Found or with nothing at all?
                 * TODO (mid): check the websocket standards, how to reply to
                 * requests to invalid websocket addresses. */
                send_http_error(conn, 404, "%s", "Not found");
                return;
        }

        /* Step 5: The websocket connection has been accepted */
        if (!send_websocket_handshake(conn, websock_key)) {
                send_http_error(conn, 500, "%s", "Websocket handshake failed");
                return;
        }

        /* Step 6: Call the ready handler */
        if (is_callback_resource) {
                if (ws_ready_handler != NULL) {
                        ws_ready_handler(conn, cbData);
                }
#if defined(USE_LUA)
        } else if (lua_websock) {
                if (!lua_websocket_ready(conn, conn->lua_websocket_state)) {
                        /* the ready handler returned false */
                        return;
                }
#endif
        }

        /* Step 7: Enter the read loop */
        if (is_callback_resource) {
                read_websocket(conn, ws_data_handler, cbData);
#if defined(USE_LUA)
        } else if (lua_websock) {
                read_websocket(conn, lua_websocket_data, conn->lua_websocket_state);
#endif
        }

        /* Step 8: Call the close handler */
        if (ws_close_handler) {
                ws_close_handler(conn, cbData);
        }
}


static int
is_websocket_protocol(const struct mg_connection *conn)
{
        const char *upgrade, *connection;

        /* A websocket protocoll has the following HTTP headers:
         *
         * Connection: Upgrade
         * Upgrade: Websocket
         */

        upgrade = mg_get_header(conn, "Upgrade");
        if (upgrade == NULL) {
                return 0; /* fail early, don't waste time checking other header
                           * fields
                             */
        }
        if (!mg_strcasestr(upgrade, "websocket")) {
                return 0;
        }

        connection = mg_get_header(conn, "Connection");
        if (connection == NULL) {
                return 0;
        }
        if (!mg_strcasestr(connection, "upgrade")) {
                return 0;
        }

        /* The headers "Host", "Sec-WebSocket-Key", "Sec-WebSocket-Protocol" and
         * "Sec-WebSocket-Version" are also required.
         * Don't check them here, since even an unsupported websocket protocol
         * request still IS a websocket request (in contrast to a standard HTTP
         * request). It will fail later in handle_websocket_request.
         */

        return 1;
}
#endif /* !USE_WEBSOCKET */


static int
isbyte(int n)
{
        return n >= 0 && n <= 255;
}


static int
parse_net(const char *spec, uint32_t *net, uint32_t *mask)
{
        int n, a, b, c, d, slash = 32, len = 0;

        if ((sscanf(spec, "%d.%d.%d.%d/%d%n", &a, &b, &c, &d, &slash, &n) == 5
             || sscanf(spec, "%d.%d.%d.%d%n", &a, &b, &c, &d, &n) == 4) && isbyte(a)
            && isbyte(b) && isbyte(c) && isbyte(d) && slash >= 0
            && slash < 33) {
                len = n;
                *net = ((uint32_t)a << 24) | ((uint32_t)b << 16) | ((uint32_t)c << 8)
                       | (uint32_t)d;
                *mask = slash ? 0xffffffffU << (32 - slash) : 0;
        }

        return len;
}


static int
set_throttle(const char *spec, uint32_t remote_ip, const char *uri)
{
        int throttle = 0;
        struct vec vec, val;
        uint32_t net, mask;
        char mult;
        double v;

        while ((spec = next_option(spec, &vec, &val)) != NULL) {
                mult = ',';
                if (sscanf(val.ptr, "%lf%c", &v, &mult) < 1 || v < 0
                    || (lowercase(&mult) != 'k' && lowercase(&mult) != 'm'
                        && mult != ',')) {
                        continue;
                }
                v *= lowercase(&mult) == 'k' ? 1024 : lowercase(&mult) == 'm' ? 1048576
                                                                              : 1;
                if (vec.len == 1 && vec.ptr[0] == '*') {
                        throttle = (int)v;
                } else if (parse_net(vec.ptr, &net, &mask) > 0) {
                        if ((remote_ip & mask) == net) {
                                throttle = (int)v;
                        }
                } else if (match_prefix(vec.ptr, vec.len, uri) > 0) {
                        throttle = (int)v;
                }
        }

        return throttle;
}


static uint32_t
get_remote_ip(const struct mg_connection *conn)
{
        if (!conn) {
                return 0;
        }
        return ntohl(*(const uint32_t *)&conn->client.rsa.sin.sin_addr);
}


/* The mg_upload function is superseeded by mg_handle_form_request. */
#include "handle_form.inl"


#if defined(MG_LEGACY_INTERFACE)
/* Implement the deprecated mg_upload function by calling the new
 * mg_handle_form_request function. While mg_upload could only handle
 * HTML forms sent as POST request in multipart/form-data format
 * containing only file input elements, mg_handle_form_request can
 * handle all form input elements and all standard request methods. */
struct mg_upload_user_data {
        struct mg_connection *conn;
        const char *destination_dir;
        int num_uploaded_files;
};


/* Helper function for deprecated mg_upload. */
static int
mg_upload_field_found(const char *key,
                      const char *filename,
                      char *path,
                      size_t pathlen,
                      void *user_data)
{
        int truncated = 0;
        struct mg_upload_user_data *fud = (struct mg_upload_user_data *)user_data;
        (void)key;

        if (!filename) {
                mg_cry(fud->conn, "%s: No filename set", __func__);
                return FORM_FIELD_STORAGE_ABORT;
        }
        mg_snprintf(fud->conn,
                    &truncated,
                    path,
                    pathlen - 1,
                    "%s/%s",
                    fud->destination_dir,
                    filename);
        if (!truncated) {
                mg_cry(fud->conn, "%s: File path too long", __func__);
                return FORM_FIELD_STORAGE_ABORT;
        }
        return FORM_FIELD_STORAGE_STORE;
}


/* Helper function for deprecated mg_upload. */
static int
mg_upload_field_get(const char *key,
                    const char *value,
                    size_t value_size,
                    void *user_data)
{
        /* Function should never be called */
        (void)key;
        (void)value;
        (void)value_size;
        (void)user_data;

        return 0;
}


/* Helper function for deprecated mg_upload. */
static int
mg_upload_field_stored(const char *path, long long file_size, void *user_data)
{
        struct mg_upload_user_data *fud = (struct mg_upload_user_data *)user_data;
        (void)file_size;

        fud->num_uploaded_files++;
        fud->conn->ctx->callbacks.upload(fud->conn, path);

        return 0;
}


/* Deprecated function mg_upload - use mg_handle_form_request instead. */
int
mg_upload(struct mg_connection *conn, const char *destination_dir)
{
        struct mg_upload_user_data fud = {conn, destination_dir, 0};
        struct mg_form_data_handler fdh = {mg_upload_field_found,
                                           mg_upload_field_get,
                                           mg_upload_field_stored,
                                           0};
        int ret;

        fdh.user_data = (void *)&fud;
        ret = mg_handle_form_request(conn, &fdh);

        if (ret < 0) {
                mg_cry(conn, "%s: Error while parsing the request", __func__);
        }

        return fud.num_uploaded_files;
}
#endif


static int
get_first_ssl_listener_index(const struct mg_context *ctx)
{
        unsigned int i;
        int idx = -1;
        if (ctx) {
                for (i = 0; idx == -1 && i < ctx->num_listening_sockets; i++) {
                        idx = ctx->listening_sockets[i].is_ssl ? ((int)(i)) : -1;
                }
        }
        return idx;
}


static void
redirect_to_https_port(struct mg_connection *conn, int ssl_index)
{
        char host[1025];
        const char *host_header;
        size_t hostlen;

        host_header = mg_get_header(conn, "Host");
        hostlen = sizeof(host);
        if (host_header != NULL) {
                char *pos;

                mg_strlcpy(host, host_header, hostlen);
                host[hostlen - 1] = '\0';
                pos = strchr(host, ':');
                if (pos != NULL) {
                        *pos = '\0';
                }
        } else {
                /* Cannot get host from the Host: header.
                 * Fallback to our IP address. */
                if (conn) {
                        sockaddr_to_string(host, hostlen, &conn->client.lsa);
                }
        }

        /* Send host, port, uri and (if it exists) ?query_string */
        if (conn) {
                mg_printf(conn,
                          "HTTP/1.1 302 Found\r\nLocation: https://%s:%d%s%s%s\r\n\r\n",
                          host,
                          (int)ntohs(
                              conn->ctx->listening_sockets[ssl_index].lsa.sin.sin_port),
                          conn->request_info.local_uri,
                          (conn->request_info.query_string == NULL) ? "" : "?",
                          (conn->request_info.query_string == NULL)
                              ? ""
                              : conn->request_info.query_string);
        }
}


static void
mg_set_handler_type(struct mg_context *ctx,
                    const char *uri,
                    int handler_type,
                    int is_delete_request,
                    mg_request_handler handler,
                    mg_websocket_connect_handler connect_handler,
                    mg_websocket_ready_handler ready_handler,
                    mg_websocket_data_handler data_handler,
                    mg_websocket_close_handler close_handler,
                    mg_authorization_handler auth_handler,
                    void *cbdata)
{
        struct mg_handler_info *tmp_rh, **lastref;
        size_t urilen = strlen(uri);

        if (handler_type == WEBSOCKET_HANDLER) {
                /* assert(handler == NULL); */
                /* assert(is_delete_request || connect_handler!=NULL ||
                 *        ready_handler!=NULL || data_handler!=NULL ||
                 *        close_handler!=NULL);
                 */
                /* assert(auth_handler == NULL); */
                if (handler != NULL) {
                        return;
                }
                if (!is_delete_request && connect_handler == NULL
                    && ready_handler == NULL
                    && data_handler == NULL
                    && close_handler == NULL) {
                        return;
                }
                if (auth_handler != NULL) {
                        return;
                }
        } else if (handler_type == REQUEST_HANDLER) {
                /* assert(connect_handler==NULL && ready_handler==NULL &&
                 *        data_handler==NULL && close_handler==NULL); */
                /* assert(is_delete_request || (handler!=NULL));
                 */
                /* assert(auth_handler == NULL); */
                if (connect_handler != NULL || ready_handler != NULL
                    || data_handler != NULL
                    || close_handler != NULL) {
                        return;
                }
                if (!is_delete_request && (handler == NULL)) {
                        return;
                }
                if (auth_handler != NULL) {
                        return;
                }
        } else { /* AUTH_HANDLER */
                     /* assert(handler == NULL); */
                     /* assert(connect_handler==NULL && ready_handler==NULL &&
                      *        data_handler==NULL && close_handler==NULL); */
                /* assert(auth_handler != NULL); */
                if (handler != NULL) {
                        return;
                }
                if (connect_handler != NULL || ready_handler != NULL
                    || data_handler != NULL
                    || close_handler != NULL) {
                        return;
                }
                if (!is_delete_request && (auth_handler == NULL)) {
                        return;
                }
        }

        if (!ctx) {
                return;
        }

        mg_lock_context(ctx);

        /* first try to find an existing handler */
        lastref = &(ctx->handlers);
        for (tmp_rh = ctx->handlers; tmp_rh != NULL; tmp_rh = tmp_rh->next) {
                if (tmp_rh->handler_type == handler_type) {
                        if (urilen == tmp_rh->uri_len && !strcmp(tmp_rh->uri, uri)) {
                                if (!is_delete_request) {
                                        /* update existing handler */
                                        if (handler_type == REQUEST_HANDLER) {
                                                tmp_rh->handler = handler;
                                        } else if (handler_type == WEBSOCKET_HANDLER) {
                                                tmp_rh->connect_handler = connect_handler;
                                                tmp_rh->ready_handler = ready_handler;
                                                tmp_rh->data_handler = data_handler;
                                                tmp_rh->close_handler = close_handler;
                                        } else { /* AUTH_HANDLER */
                                                tmp_rh->auth_handler = auth_handler;
                                        }
                                        tmp_rh->cbdata = cbdata;
                                } else {
                                        /* remove existing handler */
                                        *lastref = tmp_rh->next;
                                        mg_free(tmp_rh->uri);
                                        mg_free(tmp_rh);
                                }
                                mg_unlock_context(ctx);
                                return;
                        }
                }
                lastref = &(tmp_rh->next);
        }

        if (is_delete_request) {
                /* no handler to set, this was a remove request to a non-existing
                 * handler */
                mg_unlock_context(ctx);
                return;
        }

        tmp_rh =
            (struct mg_handler_info *)mg_calloc(sizeof(struct mg_handler_info), 1);
        if (tmp_rh == NULL) {
                mg_unlock_context(ctx);
                mg_cry(fc(ctx), "%s", "Cannot create new request handler struct, OOM");
                return;
        }
        tmp_rh->uri = mg_strdup(uri);
        if (!tmp_rh->uri) {
                mg_unlock_context(ctx);
                mg_free(tmp_rh);
                mg_cry(fc(ctx), "%s", "Cannot create new request handler struct, OOM");
                return;
        }
        tmp_rh->uri_len = urilen;
        if (handler_type == REQUEST_HANDLER) {
                tmp_rh->handler = handler;
        } else if (handler_type == WEBSOCKET_HANDLER) {
                tmp_rh->connect_handler = connect_handler;
                tmp_rh->ready_handler = ready_handler;
                tmp_rh->data_handler = data_handler;
                tmp_rh->close_handler = close_handler;
        } else { /* AUTH_HANDLER */
                tmp_rh->auth_handler = auth_handler;
        }
        tmp_rh->cbdata = cbdata;
        tmp_rh->handler_type = handler_type;
        tmp_rh->next = NULL;

        *lastref = tmp_rh;
        mg_unlock_context(ctx);
}


void
mg_set_request_handler(struct mg_context *ctx,
                       const char *uri,
                       mg_request_handler handler,
                       void *cbdata)
{
        mg_set_handler_type(ctx,
                            uri,
                            REQUEST_HANDLER,
                            handler == NULL,
                            handler,
                            NULL,
                            NULL,
                            NULL,
                            NULL,
                            NULL,
                            cbdata);
}


void
mg_set_websocket_handler(struct mg_context *ctx,
                         const char *uri,
                         mg_websocket_connect_handler connect_handler,
                         mg_websocket_ready_handler ready_handler,
                         mg_websocket_data_handler data_handler,
                         mg_websocket_close_handler close_handler,
                         void *cbdata)
{
        int is_delete_request = (connect_handler == NULL) && (ready_handler == NULL)
                                && (data_handler == NULL)
                                && (close_handler == NULL);
        mg_set_handler_type(ctx,
                            uri,
                            WEBSOCKET_HANDLER,
                            is_delete_request,
                            NULL,
                            connect_handler,
                            ready_handler,
                            data_handler,
                            close_handler,
                            NULL,
                            cbdata);
}


void
mg_set_auth_handler(struct mg_context *ctx,
                    const char *uri,
                    mg_request_handler handler,
                    void *cbdata)
{
        mg_set_handler_type(ctx,
                            uri,
                            AUTH_HANDLER,
                            handler == NULL,
                            NULL,
                            NULL,
                            NULL,
                            NULL,
                            NULL,
                            handler,
                            cbdata);
}


static int
get_request_handler(struct mg_connection *conn,
                    int handler_type,
                    mg_request_handler *handler,
                    mg_websocket_connect_handler *connect_handler,
                    mg_websocket_ready_handler *ready_handler,
                    mg_websocket_data_handler *data_handler,
                    mg_websocket_close_handler *close_handler,
                    mg_authorization_handler *auth_handler,
                    void **cbdata)
{
        const struct mg_request_info *request_info = mg_get_request_info(conn);
        if (request_info) {
                const char *uri = request_info->local_uri;
                size_t urilen = strlen(uri);
                struct mg_handler_info *tmp_rh;

                if (!conn || !conn->ctx) {
                        return 0;
                }

                mg_lock_context(conn->ctx);

                /* first try for an exact match */
                for (tmp_rh = conn->ctx->handlers; tmp_rh != NULL;
                     tmp_rh = tmp_rh->next) {
                        if (tmp_rh->handler_type == handler_type) {
                                if (urilen == tmp_rh->uri_len && !strcmp(tmp_rh->uri, uri)) {
                                        if (handler_type == WEBSOCKET_HANDLER) {
                                                *connect_handler = tmp_rh->connect_handler;
                                                *ready_handler = tmp_rh->ready_handler;
                                                *data_handler = tmp_rh->data_handler;
                                                *close_handler = tmp_rh->close_handler;
                                        } else if (handler_type == REQUEST_HANDLER) {
                                                *handler = tmp_rh->handler;
                                        } else { /* AUTH_HANDLER */
                                                *auth_handler = tmp_rh->auth_handler;
                                        }
                                        *cbdata = tmp_rh->cbdata;
                                        mg_unlock_context(conn->ctx);
                                        return 1;
                                }
                        }
                }

                /* next try for a partial match, we will accept uri/something */
                for (tmp_rh = conn->ctx->handlers; tmp_rh != NULL;
                     tmp_rh = tmp_rh->next) {
                        if (tmp_rh->handler_type == handler_type) {
                                if (tmp_rh->uri_len < urilen && uri[tmp_rh->uri_len] == '/'
                                    && memcmp(tmp_rh->uri, uri, tmp_rh->uri_len) == 0) {
                                        if (handler_type == WEBSOCKET_HANDLER) {
                                                *connect_handler = tmp_rh->connect_handler;
                                                *ready_handler = tmp_rh->ready_handler;
                                                *data_handler = tmp_rh->data_handler;
                                                *close_handler = tmp_rh->close_handler;
                                        } else if (handler_type == REQUEST_HANDLER) {
                                                *handler = tmp_rh->handler;
                                        } else { /* AUTH_HANDLER */
                                                *auth_handler = tmp_rh->auth_handler;
                                        }
                                        *cbdata = tmp_rh->cbdata;
                                        mg_unlock_context(conn->ctx);
                                        return 1;
                                }
                        }
                }

                /* finally try for pattern match */
                for (tmp_rh = conn->ctx->handlers; tmp_rh != NULL;
                     tmp_rh = tmp_rh->next) {
                        if (tmp_rh->handler_type == handler_type) {
                                if (match_prefix(tmp_rh->uri, tmp_rh->uri_len, uri) > 0) {
                                        if (handler_type == WEBSOCKET_HANDLER) {
                                                *connect_handler = tmp_rh->connect_handler;
                                                *ready_handler = tmp_rh->ready_handler;
                                                *data_handler = tmp_rh->data_handler;
                                                *close_handler = tmp_rh->close_handler;
                                        } else if (handler_type == REQUEST_HANDLER) {
                                                *handler = tmp_rh->handler;
                                        } else { /* AUTH_HANDLER */
                                                *auth_handler = tmp_rh->auth_handler;
                                        }
                                        *cbdata = tmp_rh->cbdata;
                                        mg_unlock_context(conn->ctx);
                                        return 1;
                                }
                        }
                }

                mg_unlock_context(conn->ctx);
        }
        return 0; /* none found */
}


#if defined(USE_WEBSOCKET) && defined(MG_LEGACY_INTERFACE)
static int
deprecated_websocket_connect_wrapper(const struct mg_connection *conn,
                                     void *cbdata)
{
        struct mg_callbacks *pcallbacks = (struct mg_callbacks *)cbdata;
        if (pcallbacks->websocket_connect) {
                return pcallbacks->websocket_connect(conn);
        }
        /* No handler set - assume "OK" */
        return 0;
}


static void
deprecated_websocket_ready_wrapper(struct mg_connection *conn, void *cbdata)
{
        struct mg_callbacks *pcallbacks = (struct mg_callbacks *)cbdata;
        if (pcallbacks->websocket_ready) {
                pcallbacks->websocket_ready(conn);
        }
}


static int
deprecated_websocket_data_wrapper(struct mg_connection *conn,
                                  int bits,
                                  char *data,
                                  size_t len,
                                  void *cbdata)
{
        struct mg_callbacks *pcallbacks = (struct mg_callbacks *)cbdata;
        if (pcallbacks->websocket_data) {
                return pcallbacks->websocket_data(conn, bits, data, len);
        }
        /* No handler set - assume "OK" */
        return 1;
}
#endif


/* This is the heart of the Civetweb's logic.
 * This function is called when the request is read, parsed and validated,
 * and Civetweb must decide what action to take: serve a file, or
 * a directory, or call embedded function, etcetera. */
static void
handle_request(struct mg_connection *conn)
{
        if (conn) {
                struct mg_request_info *ri = &conn->request_info;
                char path[PATH_MAX];
                int uri_len, ssl_index;
                int is_found = 0, is_script_resource = 0, is_websocket_request = 0,
                    is_put_or_delete_request = 0, is_callback_resource = 0;
                int i;
                struct file file = STRUCT_FILE_INITIALIZER;
                mg_request_handler callback_handler = NULL;
                mg_websocket_connect_handler ws_connect_handler = NULL;
                mg_websocket_ready_handler ws_ready_handler = NULL;
                mg_websocket_data_handler ws_data_handler = NULL;
                mg_websocket_close_handler ws_close_handler = NULL;
                void *callback_data = NULL;
                mg_authorization_handler auth_handler = NULL;
                void *auth_callback_data = NULL;
#if !defined(NO_FILES)
                time_t curtime = time(NULL);
                char date[64];
#endif

                path[0] = 0;

                if (!ri) {
                        return;
                }

                /* 1. get the request url */
                /* 1.1. split into url and query string */
                if ((conn->request_info.query_string = strchr(ri->request_uri, '?'))
                    != NULL) {
                        *((char *)conn->request_info.query_string++) = '\0';
                }
                uri_len = (int)strlen(ri->local_uri);

                /* 1.2. decode url (if config says so) */
                if (should_decode_url(conn)) {
                        mg_url_decode(
                            ri->local_uri, uri_len, (char *)ri->local_uri, uri_len + 1, 0);
                }

                /* 1.3. clean URIs, so a path like allowed_dir/../forbidden_file is
                 * not possible (if config says so) */
                if (!mg_strcasecmp(conn->ctx->config[CANONICALIZE_URL_PATH], "yes")) {
                        remove_double_dots_and_double_slashes((char *)ri->local_uri);
                }

                /* step 1. completed, the url is known now */
                DEBUG_TRACE("URL: %s", ri->local_uri);

                /* 2. do a https redirect, if required */
                if (!conn->client.is_ssl && conn->client.ssl_redir) {
                        ssl_index = get_first_ssl_listener_index(conn->ctx);
                        if (ssl_index >= 0) {
                                redirect_to_https_port(conn, ssl_index);
                        } else {
                                /* A http to https forward port has been specified,
                                 * but no https port to forward to. */
                                send_http_error(conn,
                                                503,
                                                "%s",
                                                "Error: SSL forward not configured properly");
                                mg_cry(conn, "Can not redirect to SSL, no SSL port available");
                        }
                        return;
                }

                /* 3. if this ip has limited speed, set it for this connection */
                conn->throttle = set_throttle(conn->ctx->config[THROTTLE],
                                              get_remote_ip(conn),
                                              ri->local_uri);

                /* 4. call a "handle everything" callback, if registered */
                if (conn->ctx->callbacks.begin_request != NULL) {
                        /* Note that since V1.7 the "begin_request" function is called
                         * before an authorization check. If an authorization check is
                         * required, use a request_handler instead. */
                        i = conn->ctx->callbacks.begin_request(conn);
                        if (i > 0) {
                                /* callback already processed the request. Store the
                                   return value as a status code for the access log. */
                                conn->status_code = i;
                                discard_unread_request_data(conn);
                                return;
                        } else if (i == 0) {
                                /* civetweb should process the request */
                        } else {
                                /* unspecified - may change with the next version */
                                return;
                        }
                }

                /* request not yet handled by a handler or redirect, so the request
                 * is processed here */

                /* 5. interpret the url to find out how the request must be handled
                 */
                /* 5.1. first test, if the request targets the regular http(s)://
                 * protocol namespace or the websocket ws(s):// protocol namespace.
                 */
                is_websocket_request = is_websocket_protocol(conn);

                /* 5.2. check if the request will be handled by a callback */
                if (get_request_handler(conn,
                                        is_websocket_request ? WEBSOCKET_HANDLER
                                                             : REQUEST_HANDLER,
                                        &callback_handler,
                                        &ws_connect_handler,
                                        &ws_ready_handler,
                                        &ws_data_handler,
                                        &ws_close_handler,
                                        NULL,
                                        &callback_data)) {
                        /* 5.2.1. A callback will handle this request. All requests
                         * handled
                         * by a callback have to be considered as requests to a script
                         * resource. */
                        is_callback_resource = 1;
                        is_script_resource = 1;
                        is_put_or_delete_request = is_put_or_delete_method(conn);
                } else {
                no_callback_resource:
                        /* 5.2.2. No callback is responsible for this request. The URI
                         * addresses a file based resource (static content or Lua/cgi
                         * scripts in the file system). */
                        is_callback_resource = 0;
                        interpret_uri(conn,
                                      path,
                                      sizeof(path),
                                      &file,
                                      &is_found,
                                      &is_script_resource,
                                      &is_websocket_request,
                                      &is_put_or_delete_request);
                }

                /* 6. authorization check */
                /* 6.1. a custom authorization handler is installed */
                if (get_request_handler(conn,
                                        AUTH_HANDLER,
                                        NULL,
                                        NULL,
                                        NULL,
                                        NULL,
                                        NULL,
                                        &auth_handler,
                                        &auth_callback_data)) {
                        if (!auth_handler(conn, auth_callback_data)) {
                                return;
                        }
                } else if (is_put_or_delete_request && !is_script_resource
                           && !is_callback_resource) {
/* 6.2. this request is a PUT/DELETE to a real file */
/* 6.2.1. thus, the server must have real files */
#if defined(NO_FILES)
                        if (1) {
#else
                        if (conn->ctx->config[DOCUMENT_ROOT] == NULL) {
#endif
                                /* This server does not have any real files, thus the
                                 * PUT/DELETE methods are not valid. */
                                send_http_error(conn,
                                                405,
                                                "%s method not allowed",
                                                conn->request_info.request_method);
                                return;
                        }

#if !defined(NO_FILES)
                        /* 6.2.2. Check if put authorization for static files is
                         * available.
                         */
                        if (!is_authorized_for_put(conn)) {
                                send_authorization_request(conn);
                                return;
                        }
#endif

                } else {
                        /* 6.3. This is either a OPTIONS, GET, HEAD or POST request,
                         * or it is a PUT or DELETE request to a resource that does not
                         * correspond to a file. Check authorization. */
                        if (!check_authorization(conn, path)) {
                                send_authorization_request(conn);
                                return;
                        }
                }

                /* request is authorized or does not need authorization */

                /* 7. check if there are request handlers for this uri */
                if (is_callback_resource) {
                        if (!is_websocket_request) {
                                i = callback_handler(conn, callback_data);
                                if (i > 0) {
                                        /* Do nothing, callback has served the request. Store
                                         * the
                                         * return value as status code for the log and discard
                                         * all
                                         * data from the client not used by the callback. */
                                        conn->status_code = i;
                                        discard_unread_request_data(conn);
                                } else {
                                        /* TODO (high): what if the handler did NOT handle the
                                         * request */
                                        /* The last version did handle this as a file request,
                                         * but
                                         * since a file request is not always a script resource,
                                         * the authorization check might be different */
                                        interpret_uri(conn,
                                                      path,
                                                      sizeof(path),
                                                      &file,
                                                      &is_found,
                                                      &is_script_resource,
                                                      &is_websocket_request,
                                                      &is_put_or_delete_request);
                                        callback_handler = NULL;

                                        /* TODO (very low): goto is deprecated but for the
                                         * moment,
                                         * a goto is simpler than some curious loop. */
                                        /* The situation "callback does not handle the request"
                                         * needs to be reconsidered anyway. */
                                        goto no_callback_resource;
                                }
                        } else {
#if defined(USE_WEBSOCKET)
                                handle_websocket_request(conn,
                                                         path,
                                                         is_callback_resource,
                                                         ws_connect_handler,
                                                         ws_ready_handler,
                                                         ws_data_handler,
                                                         ws_close_handler,
                                                         callback_data);
#endif
                        }
                        return;
                }

/* 8. handle websocket requests */
#if defined(USE_WEBSOCKET)
                if (is_websocket_request) {
                        if (is_script_resource) {
                                /* Websocket Lua script */
                                handle_websocket_request(conn,
                                                         path,
                                                         0 /* Lua Script */,
                                                         NULL,
                                                         NULL,
                                                         NULL,
                                                         NULL,
                                                         &conn->ctx->callbacks);
                        } else {
#if defined(MG_LEGACY_INTERFACE)
                                handle_websocket_request(
                                    conn,
                                    path,
                                    !is_script_resource /* could be deprecated global callback */,
                                    deprecated_websocket_connect_wrapper,
                                    deprecated_websocket_ready_wrapper,
                                    deprecated_websocket_data_wrapper,
                                    NULL,
                                    &conn->ctx->callbacks);
#else
                                send_http_error(conn, 404, "%s", "Not found");
#endif
                        }
                        return;
                } else
#endif

#if defined(NO_FILES)
                        /* 9a. In case the server uses only callbacks, this uri is
                         * unknown.
                         * Then, all request handling ends here. */
                        send_http_error(conn, 404, "%s", "Not Found");

#else
                /* 9b. This request is either for a static file or resource handled
                 * by a script file. Thus, a DOCUMENT_ROOT must exist. */
                if (conn->ctx->config[DOCUMENT_ROOT] == NULL) {
                        send_http_error(conn, 404, "%s", "Not Found");
                        return;
                }

                /* 10. File is handled by a script. */
                if (is_script_resource) {
                        handle_file_based_request(conn, path, &file);
                        return;
                }

                /* 11. Handle put/delete/mkcol requests */
                if (is_put_or_delete_request) {
                        /* 11.1. PUT method */
                        if (!strcmp(ri->request_method, "PUT")) {
                                put_file(conn, path);
                                return;
                        }
                        /* 11.2. DELETE method */
                        if (!strcmp(ri->request_method, "DELETE")) {
                                delete_file(conn, path);
                                return;
                        }
                        /* 11.3. MKCOL method */
                        if (!strcmp(ri->request_method, "MKCOL")) {
                                mkcol(conn, path);
                                return;
                        }
                        /* 11.4. PATCH method
                         * This method is not supported for static resources,
                         * only for scripts (Lua, CGI) and callbacks. */
                        send_http_error(conn,
                                        405,
                                        "%s method not allowed",
                                        conn->request_info.request_method);
                        return;
                }

                /* 11. File does not exist, or it was configured that it should be
                 * hidden */
                if (!is_found || (must_hide_file(conn, path))) {
                        send_http_error(conn, 404, "%s", "Not found");
                        return;
                }

                /* 12. Directory uris should end with a slash */
                if (file.is_directory && ri->local_uri[uri_len - 1] != '/') {
                        gmt_time_string(date, sizeof(date), &curtime);
                        mg_printf(conn,
                                  "HTTP/1.1 301 Moved Permanently\r\n"
                                  "Location: %s/\r\n"
                                  "Date: %s\r\n"
                                  /* "Cache-Control: private\r\n" (= default) */
                                  "Content-Length: 0\r\n"
                                  "Connection: %s\r\n\r\n",
                                  ri->request_uri,
                                  date,
                                  suggest_connection_header(conn));
                        return;
                }

                /* 13. Handle other methods than GET/HEAD */
                /* 13.1. Handle PROPFIND */
                if (!strcmp(ri->request_method, "PROPFIND")) {
                        handle_propfind(conn, path, &file);
                        return;
                }
                /* 13.2. Handle OPTIONS for files */
                if (!strcmp(ri->request_method, "OPTIONS")) {
                        /* This standard handler is only used for real files.
                         * Scripts should support the OPTIONS method themselves, to allow a
                         * maximum flexibility.
                         * Lua and CGI scripts may fully support CORS this way (including
                         * preflights). */
                        send_options(conn);
                        return;
                }
                /* 13.3. everything but GET and HEAD (e.g. POST) */
                if (0 != strcmp(ri->request_method, "GET")
                    && 0 != strcmp(ri->request_method, "HEAD")) {
                        send_http_error(conn,
                                        405,
                                        "%s method not allowed",
                                        conn->request_info.request_method);
                        return;
                }

                /* 14. directories */
                if (file.is_directory) {
                        if (substitute_index_file(conn, path, sizeof(path), &file)) {
                                /* 14.1. use a substitute file */
                                /* TODO (high): substitute index may be a script resource.
                                 * define what should be possible in this case. */
                        } else {
                                /* 14.2. no substitute file */
                                if (!mg_strcasecmp(conn->ctx->config[ENABLE_DIRECTORY_LISTING],
                                                   "yes")) {
                                        handle_directory_request(conn, path);
                                } else {
                                        send_http_error(conn,
                                                        403,
                                                        "%s",
                                                        "Error: Directory listing denied");
                                }
                                return;
                        }
                }

                handle_file_based_request(conn, path, &file);
#endif /* !defined(NO_FILES) */

#if 0
            /* Perform redirect and auth checks before calling begin_request()
             * handler.
             * Otherwise, begin_request() would need to perform auth checks and
             * redirects. */
#endif
        }
        return;
}


static void
handle_file_based_request(struct mg_connection *conn,
                          const char *path,
                          struct file *file)
{
        if (!conn || !conn->ctx) {
                return;
        }

        if (0) {
#ifdef USE_LUA
        } else if (match_prefix(conn->ctx->config[LUA_SERVER_PAGE_EXTENSIONS],
                                strlen(
                                    conn->ctx->config[LUA_SERVER_PAGE_EXTENSIONS]),
                                path) > 0) {
                /* Lua server page: an SSI like page containing mostly plain html
                 * code
                 * plus some tags with server generated contents. */
                handle_lsp_request(conn, path, file, NULL);
        } else if (match_prefix(conn->ctx->config[LUA_SCRIPT_EXTENSIONS],
                                strlen(conn->ctx->config[LUA_SCRIPT_EXTENSIONS]),
                                path) > 0) {
                /* Lua in-server module script: a CGI like script used to generate
                 * the
                 * entire reply. */
                mg_exec_lua_script(conn, path, NULL);
#endif
#if defined(USE_DUKTAPE)
        } else if (match_prefix(conn->ctx->config[DUKTAPE_SCRIPT_EXTENSIONS],
                                strlen(
                                    conn->ctx->config[DUKTAPE_SCRIPT_EXTENSIONS]),
                                path) > 0) {
                /* Call duktape to generate the page */
                mg_exec_duktape_script(conn, path);
#endif
#if !defined(NO_CGI)
        } else if (match_prefix(conn->ctx->config[CGI_EXTENSIONS],
                                strlen(conn->ctx->config[CGI_EXTENSIONS]),
                                path) > 0) {
                /* CGI scripts may support all HTTP methods */
                handle_cgi_request(conn, path);
#endif /* !NO_CGI */
        } else if (match_prefix(conn->ctx->config[SSI_EXTENSIONS],
                                strlen(conn->ctx->config[SSI_EXTENSIONS]),
                                path) > 0) {
                handle_ssi_file_request(conn, path, file);
#if !defined(NO_CACHING)
        } else if ((!conn->in_error_handler) && is_not_modified(conn, file)) {
                /* Send 304 "Not Modified" - this must not send any body data */
                send_http_error(conn, 304, "%s", "");
#endif /* !NO_CACHING */
        } else {
                handle_static_file_request(conn, path, file, NULL);
        }
}


static void
close_all_listening_sockets(struct mg_context *ctx)
{
        unsigned int i;
        if (!ctx) {
                return;
        }

        for (i = 0; i < ctx->num_listening_sockets; i++) {
                closesocket(ctx->listening_sockets[i].sock);
                ctx->listening_sockets[i].sock = INVALID_SOCKET;
        }
        mg_free(ctx->listening_sockets);
        ctx->listening_sockets = NULL;
        mg_free(ctx->listening_ports);
        ctx->listening_ports = NULL;
}


/* Valid listening port specification is: [ip_address:]port[s]
 * Examples for IPv4: 80, 443s, 127.0.0.1:3128, 1.2.3.4:8080s
 * Examples for IPv6: [::]:80, [::1]:80,
 *   [FEDC:BA98:7654:3210:FEDC:BA98:7654:3210]:443s
 *   see https://tools.ietf.org/html/rfc3513#section-2.2 */
static int
parse_port_string(const struct vec *vec, struct socket *so)
{
        unsigned int a, b, c, d, port;
        int ch, len;
#if defined(USE_IPV6)
        char buf[100] = {0};
#endif

        /* MacOS needs that. If we do not zero it, subsequent bind() will fail.
         * Also, all-zeroes in the socket address means binding to all addresses
         * for both IPv4 and IPv6 (INADDR_ANY and IN6ADDR_ANY_INIT). */
        memset(so, 0, sizeof(*so));
        so->lsa.sin.sin_family = AF_INET;

        if (sscanf(vec->ptr, "%u.%u.%u.%u:%u%n", &a, &b, &c, &d, &port, &len)
            == 5) {
                /* Bind to a specific IPv4 address, e.g. 192.168.1.5:8080 */
                so->lsa.sin.sin_addr.s_addr =
                    htonl((a << 24) | (b << 16) | (c << 8) | d);
                so->lsa.sin.sin_port = htons((uint16_t)port);
#if defined(USE_IPV6)
        } else if (sscanf(vec->ptr, "[%49[^]]]:%u%n", buf, &port, &len) == 2
                   && mg_inet_pton(
                          AF_INET6, buf, &so->lsa.sin6, sizeof(so->lsa.sin6))) {
                /* IPv6 address, examples: see above */
                /* so->lsa.sin6.sin6_family = AF_INET6; already set by mg_inet_pton
                 */
                so->lsa.sin6.sin6_port = htons((uint16_t)port);
#endif
        } else if (sscanf(vec->ptr, "%u%n", &port, &len) == 1) {
                /* If only port is specified, bind to IPv4, INADDR_ANY */
                so->lsa.sin.sin_port = htons((uint16_t)port);
        } else {
                /* Parsing failure. Make port invalid. */
                port = 0;
                len = 0;
        }

        /* sscanf and the option splitting code ensure the following condition
         */
        if ((len < 0) && ((unsigned)len > (unsigned)vec->len)) {
                return 0;
        }
        ch = vec->ptr[len]; /* Next character after the port number */
        so->is_ssl = (ch == 's');
        so->ssl_redir = (ch == 'r');

        /* Make sure the port is valid and vector ends with 's', 'r' or ',' */
        return is_valid_port(port)
               && (ch == '\0' || ch == 's' || ch == 'r' || ch == ',');
}


static int
set_ports_option(struct mg_context *ctx)
{
        const char *list;
        int on = 1;
#if defined(USE_IPV6)
        int off = 0;
#endif
        struct vec vec;
        struct socket so, *ptr;

        in_port_t *portPtr;
        union usa usa;
        socklen_t len;

        int portsTotal = 0;
        int portsOk = 0;

        if (!ctx) {
                return 0;
        }

        memset(&so, 0, sizeof(so));
        memset(&usa, 0, sizeof(usa));
        len = sizeof(usa);
        list = ctx->config[LISTENING_PORTS];
        while ((list = next_option(list, &vec, NULL)) != NULL) {

                portsTotal++;

                if (!parse_port_string(&vec, &so)) {
                        mg_cry(fc(ctx),
                               "%.*s: invalid port spec (entry %i). Expecting list of: %s",
                               (int)vec.len,
                               vec.ptr,
                               portsTotal,
                               "[IP_ADDRESS:]PORT[s|r]");
                        continue;
                }

                if (so.is_ssl && ctx->ssl_ctx == NULL) {

                        mg_cry(fc(ctx),
                               "Cannot add SSL socket (entry %i). Is -ssl_certificate "
                               "option set?",
                               portsTotal);
                        continue;
                }

                if ((so.sock = socket(so.lsa.sa.sa_family, SOCK_STREAM, 6))
                    == INVALID_SOCKET) {

                        mg_cry(fc(ctx), "cannot create socket (entry %i)", portsTotal);
                        continue;
                }

#ifdef _WIN32
                /* Windows SO_REUSEADDR lets many procs binds to a
                 * socket, SO_EXCLUSIVEADDRUSE makes the bind fail
                 * if someone already has the socket -- DTL */
                /* NOTE: If SO_EXCLUSIVEADDRUSE is used,
                 * Windows might need a few seconds before
                 * the same port can be used again in the
                 * same process, so a short Sleep may be
                 * required between mg_stop and mg_start.
                 */
                if (setsockopt(so.sock,
                               SOL_SOCKET,
                               SO_EXCLUSIVEADDRUSE,
                               (SOCK_OPT_TYPE)&on,
                               sizeof(on)) != 0) {

                        mg_cry(fc(ctx),
                               "cannot set socket option SO_EXCLUSIVEADDRUSE (entry %i)",
                               portsTotal);
                }
#else
                if (setsockopt(so.sock,
                               SOL_SOCKET,
                               SO_REUSEADDR,
                               (SOCK_OPT_TYPE)&on,
                               sizeof(on)) != 0) {

                        mg_cry(fc(ctx),
                               "cannot set socket option SO_REUSEADDR (entry %i)",
                               portsTotal);
                }
#endif

#if defined(USE_IPV6)
                if (so.lsa.sa.sa_family == AF_INET6
                    && setsockopt(so.sock,
                                  IPPROTO_IPV6,
                                  IPV6_V6ONLY,
                                  (void *)&off,
                                  sizeof(off)) != 0) {

                        mg_cry(fc(ctx),
                               "cannot set socket option IPV6_V6ONLY (entry %i)",
                               portsTotal);
                }
#endif

                if (so.lsa.sa.sa_family == AF_INET) {

                        len = sizeof(so.lsa.sin);
                        if (bind(so.sock, &so.lsa.sa, len) != 0) {
                                mg_cry(fc(ctx),
                                       "cannot bind to %.*s: %d (%s)",
                                       (int)vec.len,
                                       vec.ptr,
                                       (int)ERRNO,
                                       strerror(errno));
                                closesocket(so.sock);
                                so.sock = INVALID_SOCKET;
                                continue;
                        }
                }
#if defined(USE_IPV6)
                else if (so.lsa.sa.sa_family == AF_INET6) {

                        len = sizeof(so.lsa.sin6);
                        if (bind(so.sock, &so.lsa.sa, len) != 0) {
                                mg_cry(fc(ctx),
                                       "cannot bind to IPv6 %.*s: %d (%s)",
                                       (int)vec.len,
                                       vec.ptr,
                                       (int)ERRNO,
                                       strerror(errno));
                                closesocket(so.sock);
                                so.sock = INVALID_SOCKET;
                                continue;
                        }
                }
#endif
                else {
                        mg_cry(fc(ctx),
                               "cannot bind: address family not supported (entry %i)",
                               portsTotal);
                        continue;
                }

                if (listen(so.sock, SOMAXCONN) != 0) {

                        mg_cry(fc(ctx),
                               "cannot listen to %.*s: %d (%s)",
                               (int)vec.len,
                               vec.ptr,
                               (int)ERRNO,
                               strerror(errno));
                        closesocket(so.sock);
                        so.sock = INVALID_SOCKET;
                        continue;
                }

                if (getsockname(so.sock, &(usa.sa), &len) != 0) {

                        int err = (int)ERRNO;
                        mg_cry(fc(ctx),
                               "call to getsockname failed %.*s: %d (%s)",
                               (int)vec.len,
                               vec.ptr,
                               err,
                               strerror(errno));
                        closesocket(so.sock);
                        so.sock = INVALID_SOCKET;
                        continue;
                }

                if ((ptr = (struct socket *)
                         mg_realloc(ctx->listening_sockets,
                                    (ctx->num_listening_sockets + 1)
                                        * sizeof(ctx->listening_sockets[0]))) == NULL) {

                        mg_cry(fc(ctx), "%s", "Out of memory");
                        closesocket(so.sock);
                        so.sock = INVALID_SOCKET;
                        continue;
                }

                if ((portPtr =
                         (in_port_t *)mg_realloc(ctx->listening_ports,
                                                 (ctx->num_listening_sockets + 1)
                                                     * sizeof(ctx->listening_ports[0])))
                    == NULL) {

                        mg_cry(fc(ctx), "%s", "Out of memory");
                        closesocket(so.sock);
                        so.sock = INVALID_SOCKET;
                        mg_free(ptr);
                        continue;
                }

                set_close_on_exec(so.sock, fc(ctx));
                ctx->listening_sockets = ptr;
                ctx->listening_sockets[ctx->num_listening_sockets] = so;
                ctx->listening_ports = portPtr;
                ctx->listening_ports[ctx->num_listening_sockets] =
                    ntohs(usa.sin.sin_port);
                ctx->num_listening_sockets++;
                portsOk++;
        }

        if (portsOk != portsTotal) {
                close_all_listening_sockets(ctx);
                portsOk = 0;
        }

        return portsOk;
}


static const char *
header_val(const struct mg_connection *conn, const char *header)
{
        const char *header_value;

        if ((header_value = mg_get_header(conn, header)) == NULL) {
                return "-";
        } else {
                return header_value;
        }
}


static void
log_access(const struct mg_connection *conn)
{
        const struct mg_request_info *ri;
        struct file fi;
        char date[64], src_addr[IP_ADDR_STR_LEN];
        struct tm *tm;

        const char *referer;
        const char *user_agent;

        char buf[4096];

        if (!conn || !conn->ctx) {
                return;
        }

        if (conn->ctx->config[ACCESS_LOG_FILE] != NULL) {
                if (mg_fopen(conn, conn->ctx->config[ACCESS_LOG_FILE], "a+", &fi)
                    == 0) {
                        fi.fp = NULL;
                }
        } else {
                fi.fp = NULL;
        }

        if (fi.fp == NULL && conn->ctx->callbacks.log_message == NULL) {
                return;
        }

        tm = localtime(&conn->conn_birth_time);
        if (tm != NULL) {
                strftime(date, sizeof(date), "%d/%b/%Y:%H:%M:%S %z", tm);
        } else {
                mg_strlcpy(date, "01/Jan/1970:00:00:00 +0000", sizeof(date));
                date[sizeof(date) - 1] = '\0';
        }

        ri = &conn->request_info;

        sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);
        referer = header_val(conn, "Referer");
        user_agent = header_val(conn, "User-Agent");

        mg_snprintf(conn,
                    NULL, /* Ignore truncation in access log */
                    buf,
                    sizeof(buf),
                    "%s - %s [%s] \"%s %s%s%s HTTP/%s\" %d %" INT64_FMT " %s %s",
                    src_addr,
                    ri->remote_user == NULL ? "-" : ri->remote_user,
                    date,
                    ri->request_method ? ri->request_method : "-",
                    ri->request_uri ? ri->request_uri : "-",
                    ri->query_string ? "?" : "",
                    ri->query_string ? ri->query_string : "",
                    ri->http_version,
                    conn->status_code,
                    conn->num_bytes_sent,
                    referer,
                    user_agent);

        if (conn->ctx->callbacks.log_access) {
                conn->ctx->callbacks.log_access(conn, buf);
        }

        if (fi.fp) {
                flockfile(fi.fp);
                fprintf(fi.fp, "%s\n", buf);
                fflush(fi.fp);
                funlockfile(fi.fp);
                mg_fclose(&fi);
        }
}


/* Verify given socket address against the ACL.
 * Return -1 if ACL is malformed, 0 if address is disallowed, 1 if allowed.
 */
static int
check_acl(struct mg_context *ctx, uint32_t remote_ip)
{
        int allowed, flag;
        uint32_t net, mask;
        struct vec vec;

        if (ctx) {
                const char *list = ctx->config[ACCESS_CONTROL_LIST];

                /* If any ACL is set, deny by default */
                allowed = list == NULL ? '+' : '-';

                while ((list = next_option(list, &vec, NULL)) != NULL) {
                        flag = vec.ptr[0];
                        if ((flag != '+' && flag != '-')
                            || parse_net(&vec.ptr[1], &net, &mask) == 0) {
                                mg_cry(fc(ctx),
                                       "%s: subnet must be [+|-]x.x.x.x[/x]",
                                       __func__);
                                return -1;
                        }

                        if (net == (remote_ip & mask)) {
                                allowed = flag;
                        }
                }

                return allowed == '+';
        }
        return -1;
}


#if !defined(_WIN32)
static int
set_uid_option(struct mg_context *ctx)
{
        struct passwd *pw;
        if (ctx) {
                const char *uid = ctx->config[RUN_AS_USER];
                int success = 0;

                if (uid == NULL) {
                        success = 1;
                } else {
                        if ((pw = getpwnam(uid)) == NULL) {
                                mg_cry(fc(ctx), "%s: unknown user [%s]", __func__, uid);
                        } else if (setgid(pw->pw_gid) == -1) {
                                mg_cry(fc(ctx),
                                       "%s: setgid(%s): %s",
                                       __func__,
                                       uid,
                                       strerror(errno));
                        } else if (setgroups(0, NULL)) {
                                mg_cry(fc(ctx),
                                       "%s: setgroups(): %s",
                                       __func__,
                                       strerror(errno));
                        } else if (setuid(pw->pw_uid) == -1) {
                                mg_cry(fc(ctx),
                                       "%s: setuid(%s): %s",
                                       __func__,
                                       uid,
                                       strerror(errno));
                        } else {
                                success = 1;
                        }
                }

                return success;
        }
        return 0;
}
#endif /* !_WIN32 */


static void
tls_dtor(void *key)
{
        struct mg_workerTLS *tls = (struct mg_workerTLS *)key;
        /* key == pthread_getspecific(sTlsKey); */

        if (tls) {
                if (tls->is_master == 2) {
                        tls->is_master = -3; /* Mark memory as dead */
                        mg_free(tls);
                }
        }
        pthread_setspecific(sTlsKey, NULL);
}


#if !defined(NO_SSL)

/* Must be set if sizeof(pthread_t) > sizeof(unsigned long) */
static unsigned long
ssl_id_callback(void)
{
#ifdef _WIN32
        return GetCurrentThreadId();
#else

#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunreachable-code"
/* For every compiler, either "sizeof(pthread_t) > sizeof(unsigned long)"
 * or not, so one of the two conditions will be unreachable by construction.
 * Unfortunately the C standard does not define a way to check this at
 * compile time, since the #if preprocessor conditions can not use the sizeof
 * operator as an argument. */
#endif

        if (sizeof(pthread_t) > sizeof(unsigned long)) {
                /* This is the problematic case for CRYPTO_set_id_callback:
                 * The OS pthread_t can not be cast to unsigned long. */
                struct mg_workerTLS *tls =
                    (struct mg_workerTLS *)pthread_getspecific(sTlsKey);
                if (tls == NULL) {
                        /* SSL called from an unknown thread: Create some thread index.
                         */
                        tls = (struct mg_workerTLS *)mg_malloc(sizeof(struct mg_workerTLS));
                        tls->is_master = -2; /* -2 means "3rd party thread" */
                        tls->thread_idx = (unsigned)mg_atomic_inc(&thread_idx_max);
                        pthread_setspecific(sTlsKey, tls);
                }
                return tls->thread_idx;
        } else {
                /* pthread_t may be any data type, so a simple cast to unsigned long
                 * can rise a warning/error, depending on the platform.
                 * Here memcpy is used as an anything-to-anything cast. */
                unsigned long ret = 0;
                pthread_t t = pthread_self();
                memcpy(&ret, &t, sizeof(pthread_t));
                return ret;
        }

#ifdef __clang__
#pragma clang diagnostic pop
#endif

#endif
}


static int ssl_use_pem_file(struct mg_context *ctx, const char *pem);
static const char *ssl_error(void);


static int
refresh_trust(struct mg_connection *conn)
{
        static int reload_lock = 0;
        static long int data_check = 0;

        struct stat cert_buf;
        long int t;
        char *pem;
        int should_verify_peer;

        if ((pem = conn->ctx->config[SSL_CERTIFICATE]) == NULL
            && conn->ctx->callbacks.init_ssl == NULL) {
                return 0;
        }

        t = data_check;
        if (stat(pem, &cert_buf) != -1) {
                t = (long int)cert_buf.st_mtime;
        }

        if (data_check != t) {
                data_check = t;

                should_verify_peer =
                    (conn->ctx->config[SSL_DO_VERIFY_PEER] != NULL)
                    && (mg_strcasecmp(conn->ctx->config[SSL_DO_VERIFY_PEER], "yes")
                        == 0);

                if (should_verify_peer) {
                        char *ca_path = conn->ctx->config[SSL_CA_PATH];
                        char *ca_file = conn->ctx->config[SSL_CA_FILE];
                        if (SSL_CTX_load_verify_locations(conn->ctx->ssl_ctx,
                                                          ca_file,
                                                          ca_path) != 1) {
                                mg_cry(fc(conn->ctx),
                                       "SSL_CTX_load_verify_locations error: %s "
                                       "ssl_verify_peer requires setting "
                                       "either ssl_ca_path or ssl_ca_file. Is any of them "
                                       "present in "
                                       "the .conf file?",
                                       ssl_error());
                                return 0;
                        }
                }

                if (!reload_lock) {
                        reload_lock = 1;
                        if (ssl_use_pem_file(conn->ctx, pem) == 0) {
                                return 0;
                        }
                        reload_lock = 0;
                }
        }
        /* lock while cert is reloading */
        while (reload_lock) {
                sleep(1);
        }

        return 1;
}


static pthread_mutex_t *ssl_mutexes;


static int
sslize(struct mg_connection *conn, SSL_CTX *s, int (*func)(SSL *))
{
        int ret, err;
        int short_trust;

        if (!conn) {
                return 0;
        }

        short_trust =
            (conn->ctx->config[SSL_SHORT_TRUST] != NULL)
            && (mg_strcasecmp(conn->ctx->config[SSL_SHORT_TRUST], "yes") == 0);

        if (short_trust) {
                int trust_ret = refresh_trust(conn);
                if (!trust_ret) {
                        return trust_ret;
                }
        }

        conn->ssl = SSL_new(s);
        if (conn->ssl == NULL) {
                return 0;
        }

        ret = SSL_set_fd(conn->ssl, conn->client.sock);
        if (ret != 1) {
                err = SSL_get_error(conn->ssl, ret);
                (void)err; /* TODO: set some error message */
                SSL_free(conn->ssl);
                conn->ssl = NULL;
                /* maybe not? CRYPTO_cleanup_all_ex_data(); */
                /* see
                 * https://wiki.openssl.org/index.php/Talk:Library_Initialization */
                ERR_remove_state(0);
                return 0;
        }

        ret = func(conn->ssl);
        if (ret != 1) {
                err = SSL_get_error(conn->ssl, ret);
                (void)err; /* TODO: set some error message */
                SSL_free(conn->ssl);
                conn->ssl = NULL;
                /* maybe not? CRYPTO_cleanup_all_ex_data(); */
                /* see
                 * https://wiki.openssl.org/index.php/Talk:Library_Initialization */
                ERR_remove_state(0);
                return 0;
        }

        return 1;
}


/* Return OpenSSL error message (from CRYPTO lib) */
static const char *
ssl_error(void)
{
        unsigned long err;
        err = ERR_get_error();
        return err == 0 ? "" : ERR_error_string(err, NULL);
}


static void
ssl_locking_callback(int mode, int mutex_num, const char *file, int line)
{
        (void)line;
        (void)file;

        if (mode & 1) {
                /* 1 is CRYPTO_LOCK */
                (void)pthread_mutex_lock(&ssl_mutexes[mutex_num]);
        } else {
                (void)pthread_mutex_unlock(&ssl_mutexes[mutex_num]);
        }
}


#if !defined(NO_SSL_DL)
static void *
load_dll(struct mg_context *ctx, const char *dll_name, struct ssl_func *sw)
{
        union {
                void *p;
                void (*fp)(void);
        } u;
        void *dll_handle;
        struct ssl_func *fp;

        if ((dll_handle = dlopen(dll_name, RTLD_LAZY)) == NULL) {
                mg_cry(fc(ctx), "%s: cannot load %s", __func__, dll_name);
                return NULL;
        }

        for (fp = sw; fp->name != NULL; fp++) {
#ifdef _WIN32
                /* GetProcAddress() returns pointer to function */
                u.fp = (void (*)(void))dlsym(dll_handle, fp->name);
#else
                /* dlsym() on UNIX returns void *. ISO C forbids casts of data
                 * pointers to function pointers. We need to use a union to make a
                 * cast. */
                u.p = dlsym(dll_handle, fp->name);
#endif /* _WIN32 */
                if (u.fp == NULL) {
                        mg_cry(fc(ctx),
                               "%s: %s: cannot find %s",
                               __func__,
                               dll_name,
                               fp->name);
                        dlclose(dll_handle);
                        return NULL;
                } else {
                        fp->ptr = u.fp;
                }
        }

        return dll_handle;
}


static void *ssllib_dll_handle;    /* Store the ssl library handle. */
static void *cryptolib_dll_handle; /* Store the crypto library handle. */

#endif /* NO_SSL_DL */


#if defined(SSL_ALREADY_INITIALIZED)
static int cryptolib_users = 1; /* Reference counter for crypto library. */
#else
static int cryptolib_users = 0; /* Reference counter for crypto library. */
#endif


static int
initialize_ssl(struct mg_context *ctx)
{
        int i;
        size_t size;

#if !defined(NO_SSL_DL)
        if (!cryptolib_dll_handle) {
                cryptolib_dll_handle = load_dll(ctx, CRYPTO_LIB, crypto_sw);
                if (!cryptolib_dll_handle) {
                        return 0;
                }
        }
#endif /* NO_SSL_DL */

        if (mg_atomic_inc(&cryptolib_users) > 1) {
                return 1;
        }

        /* Initialize locking callbacks, needed for thread safety.
         * http://www.openssl.org/support/faq.html#PROG1
         */
        i = CRYPTO_num_locks();
        if (i < 0) {
                i = 0;
        }
        size = sizeof(pthread_mutex_t) * ((size_t)(i));
        if ((ssl_mutexes = (pthread_mutex_t *)mg_malloc(size)) == NULL) {
                mg_cry(fc(ctx),
                       "%s: cannot allocate mutexes: %s",
                       __func__,
                       ssl_error());
                return 0;
        }

        for (i = 0; i < CRYPTO_num_locks(); i++) {
                pthread_mutex_init(&ssl_mutexes[i], &pthread_mutex_attr);
        }

        CRYPTO_set_locking_callback(&ssl_locking_callback);
        CRYPTO_set_id_callback(&ssl_id_callback);

        return 1;
}


static int
ssl_use_pem_file(struct mg_context *ctx, const char *pem)
{
        if (SSL_CTX_use_certificate_file(ctx->ssl_ctx, pem, 1) == 0) {
                mg_cry(fc(ctx),
                       "%s: cannot open certificate file %s: %s",
                       __func__,
                       pem,
                       ssl_error());
                return 0;
        }

        /* could use SSL_CTX_set_default_passwd_cb_userdata */
        if (SSL_CTX_use_PrivateKey_file(ctx->ssl_ctx, pem, 1) == 0) {
                mg_cry(fc(ctx),
                       "%s: cannot open private key file %s: %s",
                       __func__,
                       pem,
                       ssl_error());
                return 0;
        }

        if (SSL_CTX_check_private_key(ctx->ssl_ctx) == 0) {
                mg_cry(fc(ctx),
                       "%s: certificate and private key do not match: %s",
                       __func__,
                       pem);
                return 0;
        }

        if (SSL_CTX_use_certificate_chain_file(ctx->ssl_ctx, pem) == 0) {
                mg_cry(fc(ctx),
                       "%s: cannot use certificate chain file %s: %s",
                       __func__,
                       pem,
                       ssl_error());
                return 0;
        }
        return 1;
}


static long
ssl_get_protocol(int version_id)
{
        long ret = SSL_OP_ALL;
        if (version_id > 0)
                ret |= SSL_OP_NO_SSLv2;
        if (version_id > 1)
                ret |= SSL_OP_NO_SSLv3;
        if (version_id > 2)
                ret |= SSL_OP_NO_TLSv1;
        if (version_id > 3)
                ret |= SSL_OP_NO_TLSv1_1;
        return ret;
}


/* Dynamically load SSL library. Set up ctx->ssl_ctx pointer. */
static int
set_ssl_option(struct mg_context *ctx)
{
        const char *pem;
        int callback_ret;
        int should_verify_peer;
        const char *ca_path;
        const char *ca_file;
        int use_default_verify_paths;
        int verify_depth;
        time_t now_rt = time(NULL);
        struct timespec now_mt;
        md5_byte_t ssl_context_id[16];
        md5_state_t md5state;
        int protocol_ver;

        /* If PEM file is not specified and the init_ssl callback
         * is not specified, skip SSL initialization. */
        if (!ctx) {
                return 0;
        }
        if ((pem = ctx->config[SSL_CERTIFICATE]) == NULL
            && ctx->callbacks.init_ssl == NULL) {
                return 1;
        }

        if (!initialize_ssl(ctx)) {
                return 0;
        }

#if !defined(NO_SSL_DL)
        if (!ssllib_dll_handle) {
                ssllib_dll_handle = load_dll(ctx, SSL_LIB, ssl_sw);
                if (!ssllib_dll_handle) {
                        return 0;
                }
        }
#endif /* NO_SSL_DL */

        /* Initialize SSL library */
        SSL_library_init();
        SSL_load_error_strings();

        if ((ctx->ssl_ctx = SSL_CTX_new(SSLv23_server_method())) == NULL) {
                mg_cry(fc(ctx), "SSL_CTX_new (server) error: %s", ssl_error());
                return 0;
        }

        SSL_CTX_clear_options(ctx->ssl_ctx,
                              SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3 | SSL_OP_NO_TLSv1
                                  | SSL_OP_NO_TLSv1_1);
        protocol_ver = atoi(ctx->config[SSL_PROTOCOL_VERSION]);
        SSL_CTX_set_options(ctx->ssl_ctx, ssl_get_protocol(protocol_ver));
        SSL_CTX_set_options(ctx->ssl_ctx, SSL_OP_SINGLE_DH_USE);
        SSL_CTX_set_ecdh_auto(ctx->ssl_ctx, 1);

        /* If a callback has been specified, call it. */
        callback_ret =
            (ctx->callbacks.init_ssl == NULL)
                ? 0
                : (ctx->callbacks.init_ssl(ctx->ssl_ctx, ctx->user_data));

        /* If callback returns 0, civetweb sets up the SSL certificate.
         * If it returns 1, civetweb assumes the calback already did this.
         * If it returns -1, initializing ssl fails. */
        if (callback_ret < 0) {
                mg_cry(fc(ctx), "SSL callback returned error: %i", callback_ret);
                return 0;
        }
        if (callback_ret > 0) {
                if (pem != NULL) {
                        (void)SSL_CTX_use_certificate_chain_file(ctx->ssl_ctx, pem);
                }
                return 1;
        }

        /* Use some UID as session context ID. */
        md5_init(&md5state);
        md5_append(&md5state, (const md5_byte_t *)&now_rt, sizeof(now_rt));
        clock_gettime(CLOCK_MONOTONIC, &now_mt);
        md5_append(&md5state, (const md5_byte_t *)&now_mt, sizeof(now_mt));
        md5_append(&md5state,
                   (const md5_byte_t *)ctx->config[LISTENING_PORTS],
                   strlen(ctx->config[LISTENING_PORTS]));
        md5_append(&md5state, (const md5_byte_t *)ctx, sizeof(*ctx));
        md5_finish(&md5state, ssl_context_id);

        SSL_CTX_set_session_id_context(ctx->ssl_ctx,
                                       (const unsigned char *)&ssl_context_id,
                                       sizeof(ssl_context_id));

        if (pem != NULL) {
                if (!ssl_use_pem_file(ctx, pem)) {
                        return 0;
                }
        }

        should_verify_peer =
            (ctx->config[SSL_DO_VERIFY_PEER] != NULL)
            && (mg_strcasecmp(ctx->config[SSL_DO_VERIFY_PEER], "yes") == 0);

        use_default_verify_paths =
            (ctx->config[SSL_DEFAULT_VERIFY_PATHS] != NULL)
            && (mg_strcasecmp(ctx->config[SSL_DEFAULT_VERIFY_PATHS], "yes") == 0);

        if (should_verify_peer) {
                ca_path = ctx->config[SSL_CA_PATH];
                ca_file = ctx->config[SSL_CA_FILE];
                if (SSL_CTX_load_verify_locations(ctx->ssl_ctx, ca_file, ca_path)
                    != 1) {
                        mg_cry(fc(ctx),
                               "SSL_CTX_load_verify_locations error: %s "
                               "ssl_verify_peer requires setting "
                               "either ssl_ca_path or ssl_ca_file. Is any of them "
                               "present in "
                               "the .conf file?",
                               ssl_error());
                        return 0;
                }

                SSL_CTX_set_verify(ctx->ssl_ctx,
                                   SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
                                   NULL);

                if (use_default_verify_paths
                    && SSL_CTX_set_default_verify_paths(ctx->ssl_ctx) != 1) {
                        mg_cry(fc(ctx),
                               "SSL_CTX_set_default_verify_paths error: %s",
                               ssl_error());
                        return 0;
                }

                if (ctx->config[SSL_VERIFY_DEPTH]) {
                        verify_depth = atoi(ctx->config[SSL_VERIFY_DEPTH]);
                        SSL_CTX_set_verify_depth(ctx->ssl_ctx, verify_depth);
                }
        }

        if (ctx->config[SSL_CIPHER_LIST] != NULL) {
                if (SSL_CTX_set_cipher_list(ctx->ssl_ctx, ctx->config[SSL_CIPHER_LIST])
                    != 1) {
                        mg_cry(fc(ctx), "SSL_CTX_set_cipher_list error: %s", ssl_error());
                }
        }

        return 1;
}


static void
uninitialize_ssl(struct mg_context *ctx)
{
        int i;
        (void)ctx;

        if (mg_atomic_dec(&cryptolib_users) == 0) {

                /* Shutdown according to
                 * https://wiki.openssl.org/index.php/Library_Initialization#Cleanup
                 * http://stackoverflow.com/questions/29845527/how-to-properly-uninitialize-openssl
                 */
                CRYPTO_set_locking_callback(NULL);
                CRYPTO_set_id_callback(NULL);
                ENGINE_cleanup();
                CONF_modules_unload(1);
                ERR_free_strings();
                EVP_cleanup();
                CRYPTO_cleanup_all_ex_data();
                ERR_remove_state(0);

                for (i = 0; i < CRYPTO_num_locks(); i++) {
                        pthread_mutex_destroy(&ssl_mutexes[i]);
                }
                mg_free(ssl_mutexes);
                ssl_mutexes = NULL;
        }
}
#endif /* !NO_SSL */


static int
set_gpass_option(struct mg_context *ctx)
{
        if (ctx) {
                struct file file = STRUCT_FILE_INITIALIZER;
                const char *path = ctx->config[GLOBAL_PASSWORDS_FILE];
                if (path != NULL && !mg_stat(fc(ctx), path, &file)) {
                        mg_cry(fc(ctx), "Cannot open %s: %s", path, strerror(ERRNO));
                        return 0;
                }
                return 1;
        }
        return 0;
}


static int
set_acl_option(struct mg_context *ctx)
{
        return check_acl(ctx, (uint32_t)0x7f000001UL) != -1;
}


static void
reset_per_request_attributes(struct mg_connection *conn)
{
        if (!conn) {
                return;
        }
        conn->path_info = NULL;
        conn->num_bytes_sent = conn->consumed_content = 0;
        conn->status_code = -1;
        conn->is_chunked = 0;
        conn->must_close = conn->request_len = conn->throttle = 0;
        conn->request_info.content_length = -1;
        conn->request_info.remote_user = NULL;
        conn->request_info.request_method = NULL;
        conn->request_info.request_uri = NULL;
        conn->request_info.local_uri = NULL;
        conn->request_info.uri = NULL; /* TODO: cleanup uri,
                                        * local_uri and request_uri */
        conn->request_info.http_version = NULL;
        conn->request_info.num_headers = 0;
        conn->data_len = 0;
        conn->chunk_remainder = 0;
        conn->internal_error = 0;
}


static int
set_sock_timeout(SOCKET sock, int milliseconds)
{
        int r0 = 0, r1, r2;

#ifdef _WIN32
        /* Windows specific */

        DWORD tv = (DWORD)milliseconds;

#else
        /* Linux, ... (not Windows) */

        struct timeval tv;

/* TCP_USER_TIMEOUT/RFC5482 (http://tools.ietf.org/html/rfc5482):
 * max. time waiting for the acknowledged of TCP data before the connection
 * will be forcefully closed and ETIMEDOUT is returned to the application.
 * If this option is not set, the default timeout of 20-30 minutes is used.
*/
/* #define TCP_USER_TIMEOUT (18) */

#if defined(TCP_USER_TIMEOUT)
        unsigned int uto = (unsigned int)milliseconds;
        r0 = setsockopt(sock, 6, TCP_USER_TIMEOUT, (const void *)&uto, sizeof(uto));
#endif

        memset(&tv, 0, sizeof(tv));
        tv.tv_sec = milliseconds / 1000;
        tv.tv_usec = (milliseconds * 1000) % 1000000;

#endif /* _WIN32 */

        r1 = setsockopt(
            sock, SOL_SOCKET, SO_RCVTIMEO, (SOCK_OPT_TYPE)&tv, sizeof(tv));
        r2 = setsockopt(
            sock, SOL_SOCKET, SO_SNDTIMEO, (SOCK_OPT_TYPE)&tv, sizeof(tv));

        return r0 || r1 || r2;
}


static int
set_tcp_nodelay(SOCKET sock, int nodelay_on)
{
        if (setsockopt(sock,
                       IPPROTO_TCP,
                       TCP_NODELAY,
                       (SOCK_OPT_TYPE)&nodelay_on,
                       sizeof(nodelay_on)) != 0) {
                /* Error */
                return 1;
        }
        /* OK */
        return 0;
}


static void
close_socket_gracefully(struct mg_connection *conn)
{
#if defined(_WIN32)
        char buf[MG_BUF_LEN];
        int n;
#endif
        struct linger linger;

        if (!conn) {
                return;
        }

        /* Set linger option to avoid socket hanging out after close. This
         * prevent
         * ephemeral port exhaust problem under high QPS. */
        linger.l_onoff = 1;
        linger.l_linger = 1;

        if (setsockopt(conn->client.sock,
                       SOL_SOCKET,
                       SO_LINGER,
                       (char *)&linger,
                       sizeof(linger)) != 0) {
                mg_cry(conn,
                       "%s: setsockopt(SOL_SOCKET SO_LINGER) failed: %s",
                       __func__,
                       strerror(ERRNO));
        }

        /* Send FIN to the client */
        shutdown(conn->client.sock, SHUT_WR);
        set_non_blocking_mode(conn->client.sock);

#if defined(_WIN32)
        /* Read and discard pending incoming data. If we do not do that and
         * close
         * the socket, the data in the send buffer may be discarded. This
         * behaviour is seen on Windows, when client keeps sending data
         * when server decides to close the connection; then when client
         * does recv() it gets no data back. */
        do {
                n = pull(
                    NULL, conn, buf, sizeof(buf), 1E-10 /* TODO: allow 0 as timeout */);
        } while (n > 0);
#endif

        /* Now we know that our FIN is ACK-ed, safe to close */
        closesocket(conn->client.sock);
        conn->client.sock = INVALID_SOCKET;
}


static void
close_connection(struct mg_connection *conn)
{
        if (!conn || !conn->ctx) {
                return;
        }

#if defined(USE_LUA) && defined(USE_WEBSOCKET)
        if (conn->lua_websocket_state) {
                lua_websocket_close(conn, conn->lua_websocket_state);
                conn->lua_websocket_state = NULL;
        }
#endif

        /* call the connection_close callback if assigned */
        if ((conn->ctx->callbacks.connection_close != NULL)
            && (conn->ctx->context_type == 1)) {
                conn->ctx->callbacks.connection_close(conn);
        }

        mg_lock_connection(conn);

        conn->must_close = 1;

#ifndef NO_SSL
        if (conn->ssl != NULL) {
                /* Run SSL_shutdown twice to ensure completly close SSL connection
                 */
                SSL_shutdown(conn->ssl);
                SSL_free(conn->ssl);
                /* maybe not? CRYPTO_cleanup_all_ex_data(); */
                /* see
                 * https://wiki.openssl.org/index.php/Talk:Library_Initialization */
                ERR_remove_state(0);
                conn->ssl = NULL;
        }
#endif
        if (conn->client.sock != INVALID_SOCKET) {
                close_socket_gracefully(conn);
                conn->client.sock = INVALID_SOCKET;
        }

        mg_unlock_connection(conn);
}

void
mg_close_connection(struct mg_connection *conn)
{
        struct mg_context *client_ctx = NULL;
        unsigned int i;

        if (conn == NULL) {
                return;
        }

        if (conn->ctx->context_type == 2) {
                client_ctx = conn->ctx;
                /* client context: loops must end */
                conn->ctx->stop_flag = 1;
        }

#ifndef NO_SSL
        if (conn->client_ssl_ctx != NULL) {
                SSL_CTX_free((SSL_CTX *)conn->client_ssl_ctx);
        }
#endif
        close_connection(conn);
        if (client_ctx != NULL) {
                /* join worker thread and free context */
                for (i = 0; i < client_ctx->cfg_worker_threads; i++) {
                        if (client_ctx->workerthreadids[i] != 0) {
                                mg_join_thread(client_ctx->workerthreadids[i]);
                        }
                }
                mg_free(client_ctx->workerthreadids);
                mg_free(client_ctx);
                (void)pthread_mutex_destroy(&conn->mutex);
                mg_free(conn);
        }
}


static struct mg_connection *
mg_connect_client_impl(const struct mg_client_options *client_options,
                       int use_ssl,
                       char *ebuf,
                       size_t ebuf_len)
{
        static struct mg_context fake_ctx;
        struct mg_connection *conn = NULL;
        SOCKET sock;
        union usa sa;

        if (!connect_socket(&fake_ctx,
                            client_options->host,
                            client_options->port,
                            use_ssl,
                            ebuf,
                            ebuf_len,
                            &sock,
                            &sa)) {
                ;
        } else if ((conn = (struct mg_connection *)
                        mg_calloc(1, sizeof(*conn) + MAX_REQUEST_SIZE)) == NULL) {
                mg_snprintf(NULL,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "calloc(): %s",
                            strerror(ERRNO));
                closesocket(sock);
#ifndef NO_SSL
        } else if (use_ssl
                   && (conn->client_ssl_ctx = SSL_CTX_new(SSLv23_client_method()))
                          == NULL) {
                mg_snprintf(NULL,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "SSL_CTX_new error");
                closesocket(sock);
                mg_free(conn);
                conn = NULL;
#endif /* NO_SSL */

        } else {

#ifdef USE_IPV6
                socklen_t len = (sa.sa.sa_family == AF_INET)
                                    ? sizeof(conn->client.rsa.sin)
                                    : sizeof(conn->client.rsa.sin6);
                struct sockaddr *psa =
                    (sa.sa.sa_family == AF_INET)
                        ? (struct sockaddr *)&(conn->client.rsa.sin)
                        : (struct sockaddr *)&(conn->client.rsa.sin6);
#else
                socklen_t len = sizeof(conn->client.rsa.sin);
                struct sockaddr *psa = (struct sockaddr *)&(conn->client.rsa.sin);
#endif

                conn->buf_size = MAX_REQUEST_SIZE;
                conn->buf = (char *)(conn + 1);
                conn->ctx = &fake_ctx;
                conn->client.sock = sock;
                conn->client.lsa = sa;

                if (getsockname(sock, psa, &len) != 0) {
                        mg_cry(conn,
                               "%s: getsockname() failed: %s",
                               __func__,
                               strerror(ERRNO));
                }

                conn->client.is_ssl = use_ssl ? 1 : 0;
                (void)pthread_mutex_init(&conn->mutex, &pthread_mutex_attr);

#ifndef NO_SSL
                if (use_ssl) {
                        fake_ctx.ssl_ctx = conn->client_ssl_ctx;

                        /* TODO: Check ssl_verify_peer and ssl_ca_path here.
                         * SSL_CTX_set_verify call is needed to switch off server
                         * certificate checking, which is off by default in OpenSSL and
                         * on in yaSSL. */
                        /* TODO: SSL_CTX_set_verify(conn->client_ssl_ctx,
                         * SSL_VERIFY_PEER, verify_ssl_server); */

                        if (client_options->client_cert) {
                                if (!ssl_use_pem_file(&fake_ctx, client_options->client_cert)) {
                                        mg_snprintf(NULL,
                                                    NULL, /* No truncation check for ebuf */
                                                    ebuf,
                                                    ebuf_len,
                                                    "Can not use SSL client certificate");
                                        SSL_CTX_free(conn->client_ssl_ctx);
                                        closesocket(sock);
                                        mg_free(conn);
                                        conn = NULL;
                                }
                        }

                        if (client_options->server_cert) {
                                SSL_CTX_load_verify_locations(conn->client_ssl_ctx,
                                                              client_options->server_cert,
                                                              NULL);
                                SSL_CTX_set_verify(conn->client_ssl_ctx, SSL_VERIFY_PEER, NULL);
                        } else {
                                SSL_CTX_set_verify(conn->client_ssl_ctx, SSL_VERIFY_NONE, NULL);
                        }

                        if (!sslize(conn, conn->client_ssl_ctx, SSL_connect)) {
                                mg_snprintf(NULL,
                                            NULL, /* No truncation check for ebuf */
                                            ebuf,
                                            ebuf_len,
                                            "SSL connection error");
                                SSL_CTX_free(conn->client_ssl_ctx);
                                closesocket(sock);
                                mg_free(conn);
                                conn = NULL;
                        }
                }
#endif
        }

        return conn;
}


CIVETWEB_API struct mg_connection *
mg_connect_client_secure(const struct mg_client_options *client_options,
                         char *error_buffer,
                         size_t error_buffer_size)
{
        return mg_connect_client_impl(client_options,
                                      1,
                                      error_buffer,
                                      error_buffer_size);
}


struct mg_connection *
mg_connect_client(const char *host,
                  int port,
                  int use_ssl,
                  char *error_buffer,
                  size_t error_buffer_size)
{
        struct mg_client_options opts;
        memset(&opts, 0, sizeof(opts));
        opts.host = host;
        opts.port = port;
        return mg_connect_client_impl(&opts,
                                      use_ssl,
                                      error_buffer,
                                      error_buffer_size);
}


static const struct {
        const char *proto;
        size_t proto_len;
        unsigned default_port;
} abs_uri_protocols[] = {{"http://", 7, 80},
                         {"https://", 8, 443},
                         {"ws://", 5, 80},
                         {"wss://", 6, 443},
                         {NULL, 0, 0}};


/* Check if the uri is valid.
 * return 0 for invalid uri,
 * return 1 for *,
 * return 2 for relative uri,
 * return 3 for absolute uri without port,
 * return 4 for absolute uri with port */
static int
get_uri_type(const char *uri)
{
        int i;
        char *hostend, *portbegin, *portend;
        unsigned long port;

        /* According to the HTTP standard
         * http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.1.2
         * URI can be an asterisk (*) or should start with slash (relative uri),
         * or it should start with the protocol (absolute uri). */
        if (uri[0] == '*' && uri[1] == '\0') {
                /* asterisk */
                return 1;
        }
        if (uri[0] == '/') {
                /* relative uri */
                return 2;
        }

        /* It could be an absolute uri: */
        /* This function only checks if the uri is valid, not if it is
         * addressing the current server. So civetweb can also be used
         * as a proxy server. */
        for (i = 0; abs_uri_protocols[i].proto != NULL; i++) {
                if (mg_strncasecmp(uri,
                                   abs_uri_protocols[i].proto,
                                   abs_uri_protocols[i].proto_len) == 0) {

                        hostend = strchr(uri + abs_uri_protocols[i].proto_len, '/');
                        if (!hostend) {
                                return 0;
                        }
                        portbegin = strchr(uri + abs_uri_protocols[i].proto_len, ':');
                        if (!portbegin) {
                                return 3;
                        }

                        port = strtoul(portbegin + 1, &portend, 10);
                        if ((portend != hostend) || !port || !is_valid_port(port)) {
                                return 0;
                        }

                        return 4;
                }
        }

        return 0;
}


/* Return NULL or the relative uri at the current server */
static const char *
get_rel_url_at_current_server(const char *uri, const struct mg_connection *conn)
{
        const char *server_domain;
        size_t server_domain_len;
        size_t request_domain_len = 0;
        unsigned long port = 0;
        int i, auth_domain_check_enabled;
        const char *hostbegin = NULL;
        const char *hostend = NULL;
        const char *portbegin;
        char *portend;

        auth_domain_check_enabled =
                !strcmp(conn->ctx->config[ENABLE_AUTH_DOMAIN_CHECK],"yes");
        /* DNS is case insensitive, so use case insensitive string compare here
         */
        server_domain = conn->ctx->config[AUTHENTICATION_DOMAIN];
        if (!server_domain && auth_domain_check_enabled) {
                return 0;
        }
        server_domain_len = strlen(server_domain);
        if (!server_domain_len) {
                return 0;
        }

        for (i = 0; abs_uri_protocols[i].proto != NULL; i++) {
                if (mg_strncasecmp(uri,
                                   abs_uri_protocols[i].proto,
                                   abs_uri_protocols[i].proto_len) == 0) {

                        hostbegin = uri + abs_uri_protocols[i].proto_len;
                        hostend = strchr(hostbegin, '/');
                        if (!hostend) {
                                return 0;
                        }
                        portbegin = strchr(hostbegin, ':');
                        if ((!portbegin) || (portbegin > hostend)) {
                                port = abs_uri_protocols[i].default_port;
                                request_domain_len = (size_t)(hostend - hostbegin);
                        } else {
                                port = strtoul(portbegin + 1, &portend, 10);
                                if ((portend != hostend) || !port || !is_valid_port(port)) {
                                        return 0;
                                }
                                request_domain_len = (size_t)(portbegin - hostbegin);
                        }
                        /* protocol found, port set */
                        break;
                }
        }

        if (!port) {
                /* port remains 0 if the protocol is not found */
                return 0;
        }

/* Check if the request is directed to a different server. */
/* First check if the port is the same (IPv4 and IPv6). */
#if defined(USE_IPV6)
        if (conn->client.lsa.sa.sa_family == AF_INET6) {
                if (ntohs(conn->client.lsa.sin6.sin6_port) != port) {
                        /* Request is directed to a different port */
                        return 0;
                }
        } else
#endif
        {
                if (ntohs(conn->client.lsa.sin.sin_port) != port) {
                        /* Request is directed to a different port */
                        return 0;
                }
        }

        /* Finally check if the server corresponds to the authentication
         * domain of the server (the server domain).
         * Allow full matches (like http://mydomain.com/path/file.ext), and
         * allow subdomain matches (like http://www.mydomain.com/path/file.ext),
         * but do not allow substrings (like http://notmydomain.com/path/file.ext
         * or http://mydomain.com.fake/path/file.ext).
         */
        if (auth_domain_check_enabled) {
                if ((request_domain_len == server_domain_len)
                                && (!memcmp(server_domain, hostbegin, server_domain_len))) {
                        /* Request is directed to this server - full name match. */
                } else {
                        if (request_domain_len < (server_domain_len + 2)) {
                                /* Request is directed to another server: The server name is longer
                                 * than
                                 * the request name. Drop this case here to avoid overflows in the
                                 * following checks. */
                                return 0;
                        }
                        if (hostbegin[request_domain_len - server_domain_len - 1] != '.') {
                                /* Request is directed to another server: It could be a substring
                                 * like notmyserver.com */
                                return 0;
                        }
                        if (0 != memcmp(server_domain,
                                                                                        hostbegin + request_domain_len - server_domain_len,
                                                                                        server_domain_len)) {
                                /* Request is directed to another server:
                                 * The server name is different. */
                                return 0;
                        }
                }
        }

        return hostend;
}


static int
getreq(struct mg_connection *conn, char *ebuf, size_t ebuf_len, int *err)
{
        const char *cl;
        int check_method = should_validate_http_method(conn);

        if (ebuf_len > 0) {
                ebuf[0] = '\0';
        }
        *err = 0;

        reset_per_request_attributes(conn);

        if (!conn) {
                mg_snprintf(conn,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "%s",
                            "Internal error");
                *err = 500;
                return 0;
        }
        /* Set the time the request was received. This value should be used for
         * timeouts. */
        clock_gettime(CLOCK_MONOTONIC, &(conn->req_time));

        conn->request_len =
            read_request(NULL, conn, conn->buf, conn->buf_size, &conn->data_len);
        /* assert(conn->request_len < 0 || conn->data_len >= conn->request_len);
         */
        if (conn->request_len >= 0 && conn->data_len < conn->request_len) {
                mg_snprintf(conn,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "%s",
                            "Invalid request size");
                *err = 500;
                return 0;
        }

        if (conn->request_len == 0 && conn->data_len == conn->buf_size) {
                mg_snprintf(conn,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "%s",
                            "Request Too Large");
                *err = 413;
                return 0;
        } else if (conn->request_len <= 0) {
                if (conn->data_len > 0) {
                        mg_snprintf(conn,
                                    NULL, /* No truncation check for ebuf */
                                    ebuf,
                                    ebuf_len,
                                    "%s",
                                    "Client sent malformed request");
                        *err = 400;
                } else {
                        /* Server did not send anything -> just close the connection */
                        conn->must_close = 1;
                        mg_snprintf(conn,
                                    NULL, /* No truncation check for ebuf */
                                    ebuf,
                                    ebuf_len,
                                    "%s",
                                    "Client did not send a request");
                        *err = 0;
                }
                return 0;
        } else if (parse_http_message(
                       check_method, conn->buf, conn->buf_size, &conn->request_info)
                   <= 0) {
                mg_snprintf(conn,
                            NULL, /* No truncation check for ebuf */
                            ebuf,
                            ebuf_len,
                            "%s",
                            "Bad Request");
                *err = 400;
                return 0;
        } else {
                /* Message is a valid request or response */
                if ((cl = get_header(&conn->request_info, "Transfer-Encoding"))
                               != NULL
                           && !mg_strcasecmp(cl, "chunked")) {
                        conn->is_chunked = 1;
                        conn->content_len = 0;
                } else if ((cl = get_header(&conn->request_info, "Content-Length")) != NULL) {
                        /* Request/response has content length set */
                        char *endptr = NULL;
                        conn->content_len = strtoll(cl, &endptr, 10);
                        if (endptr == cl) {
                                mg_snprintf(conn,
                                            NULL, /* No truncation check for ebuf */
                                            ebuf,
                                            ebuf_len,
                                            "%s",
                                            "Bad Request");
                                *err = 400;
                                return 0;
                        }
                        /* Publish the content length back to the request info. */
                        conn->request_info.content_length = conn->content_len;
                } else if (!mg_strcasecmp(conn->request_info.request_method, "POST")
                           || !mg_strcasecmp(conn->request_info.request_method,
                                             "PUT")) {
                        /* POST or PUT request without content length set */
                        conn->content_len = -1;
                } else if (!mg_strncasecmp(conn->request_info.request_method,
                                           "HTTP/",
                                           5)) {
                        /* Response without content length set */
                        conn->content_len = -1;
                } else {
                        /* Other request */
                        conn->content_len = 0;
                }
        }
        return 1;
}


int
mg_get_response(struct mg_connection *conn,
                char *ebuf,
                size_t ebuf_len,
                int timeout)
{
        if (conn) {
                /* Implementation of API function for HTTP clients */
                int err, ret;
                struct mg_context *octx = conn->ctx;
                struct mg_context rctx = *(conn->ctx);
                char txt[32]; /* will not overflow */

                if (timeout >= 0) {
                        mg_snprintf(conn, NULL, txt, sizeof(txt), "%i", timeout);
                        rctx.config[REQUEST_TIMEOUT] = txt;
                        set_sock_timeout(conn->client.sock, timeout);
                } else {
                        rctx.config[REQUEST_TIMEOUT] = NULL;
                }

                conn->ctx = &rctx;
                ret = getreq(conn, ebuf, ebuf_len, &err);
                conn->ctx = octx;

                /* TODO: 1) uri is deprecated;
                 *       2) here, ri.uri is the http response code */
                conn->request_info.uri = conn->request_info.request_uri;

                /* TODO (mid): Define proper return values - maybe return length?
                 * For the first test use <0 for error and >0 for OK */
                return (ret == 0) ? -1 : +1;
        }
        return -1;
}


struct mg_connection *
mg_download(const char *host,
            int port,
            int use_ssl,
            char *ebuf,
            size_t ebuf_len,
            const char *fmt,
            ...)
{
        struct mg_connection *conn;
        va_list ap;
        int i;
        int reqerr;

        va_start(ap, fmt);
        ebuf[0] = '\0';

        /* open a connection */
        conn = mg_connect_client(host, port, use_ssl, ebuf, ebuf_len);

        if (conn != NULL) {
                i = mg_vprintf(conn, fmt, ap);
                if (i <= 0) {
                        mg_snprintf(conn,
                                    NULL, /* No truncation check for ebuf */
                                    ebuf,
                                    ebuf_len,
                                    "%s",
                                    "Error sending request");
                } else {
                        getreq(conn, ebuf, ebuf_len, &reqerr);

                        /* TODO: 1) uri is deprecated;
                         *       2) here, ri.uri is the http response code */
                        conn->request_info.uri = conn->request_info.request_uri;
                }
        }

        /* if an error occured, close the connection */
        if (ebuf[0] != '\0' && conn != NULL) {
                mg_close_connection(conn);
                conn = NULL;
        }

        va_end(ap);
        return conn;
}


struct websocket_client_thread_data {
        struct mg_connection *conn;
        mg_websocket_data_handler data_handler;
        mg_websocket_close_handler close_handler;
        void *callback_data;
};


#if defined(USE_WEBSOCKET)
#ifdef _WIN32
static unsigned __stdcall websocket_client_thread(void *data)
#else
static void *
websocket_client_thread(void *data)
#endif
{
        struct websocket_client_thread_data *cdata =
            (struct websocket_client_thread_data *)data;

        mg_set_thread_name("ws-client");

        if (cdata->conn->ctx) {
                if (cdata->conn->ctx->callbacks.init_thread) {
                        /* 3 indicates a websocket client thread */
                        /* TODO: check if conn->ctx can be set */
                        cdata->conn->ctx->callbacks.init_thread(cdata->conn->ctx, 3);
                }
        }

        read_websocket(cdata->conn, cdata->data_handler, cdata->callback_data);

        DEBUG_TRACE("%s", "Websocket client thread exited\n");

        if (cdata->close_handler != NULL) {
                cdata->close_handler(cdata->conn, cdata->callback_data);
        }

        mg_free((void *)cdata);

#ifdef _WIN32
        return 0;
#else
        return NULL;
#endif
}
#endif


struct mg_connection *
mg_connect_websocket_client(const char *host,
                            int port,
                            int use_ssl,
                            char *error_buffer,
                            size_t error_buffer_size,
                            const char *path,
                            const char *origin,
                            mg_websocket_data_handler data_func,
                            mg_websocket_close_handler close_func,
                            void *user_data)
{
        struct mg_connection *conn = NULL;

#if defined(USE_WEBSOCKET)
        struct mg_context *newctx = NULL;
        struct websocket_client_thread_data *thread_data;
        static const char *magic = "x3JJHMbDL1EzLkh9GBhXDw==";
        static const char *handshake_req;

        if (origin != NULL) {
                handshake_req = "GET %s HTTP/1.1\r\n"
                                "Host: %s\r\n"
                                "Upgrade: websocket\r\n"
                                "Connection: Upgrade\r\n"
                                "Sec-WebSocket-Key: %s\r\n"
                                "Sec-WebSocket-Version: 13\r\n"
                                "Origin: %s\r\n"
                                "\r\n";
        } else {
                handshake_req = "GET %s HTTP/1.1\r\n"
                                "Host: %s\r\n"
                                "Upgrade: websocket\r\n"
                                "Connection: Upgrade\r\n"
                                "Sec-WebSocket-Key: %s\r\n"
                                "Sec-WebSocket-Version: 13\r\n"
                                "\r\n";
        }

        /* Establish the client connection and request upgrade */
        conn = mg_download(host,
                           port,
                           use_ssl,
                           error_buffer,
                           error_buffer_size,
                           handshake_req,
                           path,
                           host,
                           magic,
                           origin);

        /* Connection object will be null if something goes wrong */
        if (conn == NULL || (strcmp(conn->request_info.request_uri, "101") != 0)) {
                if (!*error_buffer) {
                        /* if there is a connection, but it did not return 101,
                         * error_buffer is not yet set */
                        mg_snprintf(conn,
                                    NULL, /* No truncation check for ebuf */
                                    error_buffer,
                                    error_buffer_size,
                                    "Unexpected server reply");
                }
                DEBUG_TRACE("Websocket client connect error: %s\r\n", error_buffer);
                if (conn != NULL) {
                        mg_free(conn);
                        conn = NULL;
                }
                return conn;
        }

        /* For client connections, mg_context is fake. Since we need to set a
         * callback function, we need to create a copy and modify it. */
        newctx = (struct mg_context *)mg_malloc(sizeof(struct mg_context));
        memcpy(newctx, conn->ctx, sizeof(struct mg_context));
        newctx->user_data = user_data;
        newctx->context_type = 2;       /* client context type */
        newctx->cfg_worker_threads = 1; /* one worker thread will be created */
        newctx->workerthreadids =
            (pthread_t *)mg_calloc(newctx->cfg_worker_threads, sizeof(pthread_t));
        conn->ctx = newctx;
        thread_data = (struct websocket_client_thread_data *)
            mg_calloc(sizeof(struct websocket_client_thread_data), 1);
        thread_data->conn = conn;
        thread_data->data_handler = data_func;
        thread_data->close_handler = close_func;
        thread_data->callback_data = NULL;

        /* Start a thread to read the websocket client connection
         * This thread will automatically stop when mg_disconnect is
         * called on the client connection */
        if (mg_start_thread_with_id(websocket_client_thread,
                                    (void *)thread_data,
                                    newctx->workerthreadids) != 0) {
                mg_free((void *)thread_data);
                mg_free((void *)newctx->workerthreadids);
                mg_free((void *)newctx);
                mg_free((void *)conn);
                conn = NULL;
                DEBUG_TRACE("%s",
                            "Websocket client connect thread could not be started\r\n");
        }
#else
        /* Appease "unused parameter" warnings */
        (void)host;
        (void)port;
        (void)use_ssl;
        (void)error_buffer;
        (void)error_buffer_size;
        (void)path;
        (void)origin;
        (void)user_data;
        (void)data_func;
        (void)close_func;
#endif

        return conn;
}


static void
process_new_connection(struct mg_connection *conn)
{
        if (conn && conn->ctx) {
                struct mg_request_info *ri = &conn->request_info;
                int keep_alive_enabled, keep_alive, discard_len;
                char ebuf[100];
                const char *hostend;
                int reqerr, uri_type;

                keep_alive_enabled =
                    !strcmp(conn->ctx->config[ENABLE_KEEP_ALIVE], "yes");

                /* Important: on new connection, reset the receiving buffer. Credit
                 * goes to crule42. */
                conn->data_len = 0;
                do {
                        if (!getreq(conn, ebuf, sizeof(ebuf), &reqerr)) {
                                /* The request sent by the client could not be understood by
                                 * the server, or it was incomplete or a timeout. Send an
                                 * error message and close the connection. */
                                if (reqerr > 0) {
                                        /*assert(ebuf[0] != '\0');*/
                                        send_http_error(conn, reqerr, "%s", ebuf);
                                }
                        } else if (strcmp(ri->http_version, "1.0")
                                   && strcmp(ri->http_version, "1.1")) {
                                mg_snprintf(conn,
                                            NULL, /* No truncation check for ebuf */
                                            ebuf,
                                            sizeof(ebuf),
                                            "Bad HTTP version: [%s]",
                                            ri->http_version);
                                send_http_error(conn, 505, "%s", ebuf);
                        }

                        if (ebuf[0] == '\0') {
                                uri_type = get_uri_type(conn->request_info.request_uri);
                                switch (uri_type) {
                                case 1:
                                        /* Asterisk */
                                        conn->request_info.local_uri = NULL;
                                        break;
                                case 2:
                                        /* relative uri */
                                        conn->request_info.local_uri =
                                            conn->request_info.request_uri;
                                        break;
                                case 3:
                                case 4:
                                        /* absolute uri (with/without port) */
                                        hostend = get_rel_url_at_current_server(
                                            conn->request_info.request_uri, conn);
                                        if (hostend) {
                                                conn->request_info.local_uri = hostend;
                                        } else {
                                                conn->request_info.local_uri = NULL;
                                        }
                                        break;
                                default:
                                        mg_snprintf(conn,
                                                    NULL, /* No truncation check for ebuf */
                                                    ebuf,
                                                    sizeof(ebuf),
                                                    "Invalid URI: [%s]",
                                                    ri->request_uri);
                                        send_http_error(conn, 400, "%s", ebuf);
                                        break;
                                }

                                /* TODO: cleanup uri, local_uri and request_uri */
                                conn->request_info.uri = conn->request_info.local_uri;
                        }

                        if (ebuf[0] == '\0') {
                                if (conn->request_info.local_uri) {
                                        /* handle request to local server */
                                        handle_request(conn);
                                        if (conn->ctx->callbacks.end_request != NULL) {
                                                conn->ctx->callbacks.end_request(conn,
                                                                                 conn->status_code);
                                        }
                                        log_access(conn);
                                } else {
                                        /* TODO: handle non-local request (PROXY) */
                                        conn->must_close = 1;
                                }
                        } else {
                                conn->must_close = 1;
                        }

                        if (ri->remote_user != NULL) {
                                mg_free((void *)ri->remote_user);
                                /* Important! When having connections with and without auth
                                 * would cause double free and then crash */
                                ri->remote_user = NULL;
                        }

                        /* NOTE(lsm): order is important here. should_keep_alive() call
                         * is
                         * using parsed request, which will be invalid after memmove's
                         * below.
                         * Therefore, memorize should_keep_alive() result now for later
                         * use
                         * in loop exit condition. */
                        keep_alive = conn->ctx->stop_flag == 0 && keep_alive_enabled
                                     && conn->content_len >= 0 && should_keep_alive(conn);

                        /* Discard all buffered data for this request */
                        discard_len = conn->content_len >= 0 && conn->request_len > 0
                                              && conn->request_len + conn->content_len
                                                     < (int64_t)conn->data_len
                                          ? (int)(conn->request_len + conn->content_len)
                                          : conn->data_len;
                        /*assert(discard_len >= 0);*/
                        if (discard_len < 0)
                                break;
                        conn->data_len -= discard_len;
                        if (conn->data_len > 0) {
                                memmove(conn->buf,
                                        conn->buf + discard_len,
                                        (size_t)conn->data_len);
                        }

                        /* assert(conn->data_len >= 0); */
                        /* assert(conn->data_len <= conn->buf_size); */

                        if ((conn->data_len < 0) || (conn->data_len > conn->buf_size)) {
                                break;
                        }

                } while (keep_alive);
        }
}


/* Worker threads take accepted socket from the queue */
static int
consume_socket(struct mg_context *ctx, struct socket *sp)
{
#define QUEUE_SIZE(ctx) ((int)(ARRAY_SIZE(ctx->queue)))
        if (!ctx) {
                return 0;
        }

        (void)pthread_mutex_lock(&ctx->thread_mutex);
        DEBUG_TRACE("%s", "going idle");

        /* If the queue is empty, wait. We're idle at this point. */
        while (ctx->sq_head == ctx->sq_tail && ctx->stop_flag == 0) {
                pthread_cond_wait(&ctx->sq_full, &ctx->thread_mutex);
        }

        /* If we're stopping, sq_head may be equal to sq_tail. */
        if (ctx->sq_head > ctx->sq_tail) {
                /* Copy socket from the queue and increment tail */
                *sp = ctx->queue[ctx->sq_tail % QUEUE_SIZE(ctx)];
                ctx->sq_tail++;

                DEBUG_TRACE("grabbed socket %d, going busy", sp ? sp->sock : -1);

                /* Wrap pointers if needed */
                while (ctx->sq_tail > QUEUE_SIZE(ctx)) {
                        ctx->sq_tail -= QUEUE_SIZE(ctx);
                        ctx->sq_head -= QUEUE_SIZE(ctx);
                }
        }

        (void)pthread_cond_signal(&ctx->sq_empty);
        (void)pthread_mutex_unlock(&ctx->thread_mutex);

        return !ctx->stop_flag;
#undef QUEUE_SIZE
}


static void *
worker_thread_run(void *thread_func_param)
{
        struct mg_context *ctx = (struct mg_context *)thread_func_param;
        struct mg_connection *conn;
        struct mg_workerTLS tls;
#if defined(MG_LEGACY_INTERFACE)
        uint32_t addr;
#endif

        mg_set_thread_name("worker");

        tls.is_master = 0;
        tls.thread_idx = (unsigned)mg_atomic_inc(&thread_idx_max);
#if defined(_WIN32) && !defined(__SYMBIAN32__)
        tls.pthread_cond_helper_mutex = CreateEvent(NULL, FALSE, FALSE, NULL);
#endif

        if (ctx->callbacks.init_thread) {
                /* call init_thread for a worker thread (type 1) */
                ctx->callbacks.init_thread(ctx, 1);
        }

        conn =
            (struct mg_connection *)mg_calloc(1, sizeof(*conn) + MAX_REQUEST_SIZE);
        if (conn == NULL) {
                mg_cry(fc(ctx), "%s", "Cannot create new connection struct, OOM");
        } else {
                pthread_setspecific(sTlsKey, &tls);
                conn->buf_size = MAX_REQUEST_SIZE;
                conn->buf = (char *)(conn + 1);
                conn->ctx = ctx;
                conn->request_info.user_data = ctx->user_data;
                /* Allocate a mutex for this connection to allow communication both
                 * within the request handler and from elsewhere in the application
                 */
                (void)pthread_mutex_init(&conn->mutex, &pthread_mutex_attr);

                /* Call consume_socket() even when ctx->stop_flag > 0, to let it
                 * signal sq_empty condvar to wake up the master waiting in
                 * produce_socket() */
                while (consume_socket(ctx, &conn->client)) {
                        conn->conn_birth_time = time(NULL);

/* Fill in IP, port info early so even if SSL setup below fails,
 * error handler would have the corresponding info.
 * Thanks to Johannes Winkelmann for the patch.
 */
#if defined(USE_IPV6)
                        if (conn->client.rsa.sa.sa_family == AF_INET6) {
                                conn->request_info.remote_port =
                                    ntohs(conn->client.rsa.sin6.sin6_port);
                        } else
#endif
                        {
                                conn->request_info.remote_port =
                                    ntohs(conn->client.rsa.sin.sin_port);
                        }

                        sockaddr_to_string(conn->request_info.remote_addr,
                                           sizeof(conn->request_info.remote_addr),
                                           &conn->client.rsa);

#if defined(MG_LEGACY_INTERFACE)
                        /* This legacy interface only works for the IPv4 case */
                        addr = ntohl(conn->client.rsa.sin.sin_addr.s_addr);
                        memcpy(&conn->request_info.remote_ip, &addr, 4);
#endif

                        conn->request_info.is_ssl = conn->client.is_ssl;

                        if (!conn->client.is_ssl
#ifndef NO_SSL
                            || sslize(conn, conn->ctx->ssl_ctx, SSL_accept)
#endif
                                ) {


                                process_new_connection(conn);
                        }

                        close_connection(conn);
                }
        }

        /* Signal master that we're done with connection and exiting */
        (void)pthread_mutex_lock(&ctx->thread_mutex);
        ctx->running_worker_threads--;
        (void)pthread_cond_signal(&ctx->thread_cond);
        /* assert(ctx->running_worker_threads >= 0); */
        (void)pthread_mutex_unlock(&ctx->thread_mutex);

        pthread_setspecific(sTlsKey, NULL);
#if defined(_WIN32) && !defined(__SYMBIAN32__)
        CloseHandle(tls.pthread_cond_helper_mutex);
#endif
        pthread_mutex_destroy(&conn->mutex);
        mg_free(conn);

        DEBUG_TRACE("%s", "exiting");
        return NULL;
}


/* Threads have different return types on Windows and Unix. */
#ifdef _WIN32
static unsigned __stdcall worker_thread(void *thread_func_param)
{
        worker_thread_run(thread_func_param);
        return 0;
}
#else
static void *
worker_thread(void *thread_func_param)
{
        worker_thread_run(thread_func_param);
        return NULL;
}
#endif /* _WIN32 */


/* Master thread adds accepted socket to a queue */
static void
produce_socket(struct mg_context *ctx, const struct socket *sp)
{
#define QUEUE_SIZE(ctx) ((int)(ARRAY_SIZE(ctx->queue)))
        if (!ctx) {
                return;
        }
        (void)pthread_mutex_lock(&ctx->thread_mutex);

        /* If the queue is full, wait */
        while (ctx->stop_flag == 0
               && ctx->sq_head - ctx->sq_tail >= QUEUE_SIZE(ctx)) {
                (void)pthread_cond_wait(&ctx->sq_empty, &ctx->thread_mutex);
        }

        if (ctx->sq_head - ctx->sq_tail < QUEUE_SIZE(ctx)) {
                /* Copy socket to the queue and increment head */
                ctx->queue[ctx->sq_head % QUEUE_SIZE(ctx)] = *sp;
                ctx->sq_head++;
                DEBUG_TRACE("queued socket %d", sp ? sp->sock : -1);
        }

        (void)pthread_cond_signal(&ctx->sq_full);
        (void)pthread_mutex_unlock(&ctx->thread_mutex);
#undef QUEUE_SIZE
}


static void
accept_new_connection(const struct socket *listener, struct mg_context *ctx)
{
        struct socket so;
        char src_addr[IP_ADDR_STR_LEN];
        socklen_t len = sizeof(so.rsa);
        int on = 1;
        int timeout;

        if (!listener) {
                return;
        }

        if ((so.sock = accept(listener->sock, &so.rsa.sa, &len))
            == INVALID_SOCKET) {
        } else if (!check_acl(ctx, ntohl(*(uint32_t *)&so.rsa.sin.sin_addr))) {
                sockaddr_to_string(src_addr, sizeof(src_addr), &so.rsa);
                mg_cry(fc(ctx), "%s: %s is not allowed to connect", __func__, src_addr);
                closesocket(so.sock);
                so.sock = INVALID_SOCKET;
        } else {
                /* Put so socket structure into the queue */
                DEBUG_TRACE("Accepted socket %d", (int)so.sock);
                set_close_on_exec(so.sock, fc(ctx));
                so.is_ssl = listener->is_ssl;
                so.ssl_redir = listener->ssl_redir;
                if (getsockname(so.sock, &so.lsa.sa, &len) != 0) {
                        mg_cry(fc(ctx),
                               "%s: getsockname() failed: %s",
                               __func__,
                               strerror(ERRNO));
                }

                /* Set TCP keep-alive. This is needed because if HTTP-level
                 * keep-alive
                 * is enabled, and client resets the connection, server won't get
                 * TCP FIN or RST and will keep the connection open forever. With
                 * TCP keep-alive, next keep-alive handshake will figure out that
                 * the client is down and will close the server end.
                 * Thanks to Igor Klopov who suggested the patch. */
                if (setsockopt(so.sock,
                               SOL_SOCKET,
                               SO_KEEPALIVE,
                               (SOCK_OPT_TYPE)&on,
                               sizeof(on)) != 0) {
                        mg_cry(fc(ctx),
                               "%s: setsockopt(SOL_SOCKET SO_KEEPALIVE) failed: %s",
                               __func__,
                               strerror(ERRNO));
                }


                /* Disable TCP Nagle's algorithm.  Normally TCP packets are
                 * coalesced
                 * to effectively fill up the underlying IP packet payload and
                 * reduce
                 * the overhead of sending lots of small buffers. However this hurts
                 * the server's throughput (ie. operations per second) when HTTP 1.1
                 * persistent connections are used and the responses are relatively
                 * small (eg. less than 1400 bytes).
                 */
                if ((ctx != NULL) && (ctx->config[CONFIG_TCP_NODELAY] != NULL)
                    && (!strcmp(ctx->config[CONFIG_TCP_NODELAY], "1"))) {
                        if (set_tcp_nodelay(so.sock, 1) != 0) {
                                mg_cry(fc(ctx),
                                       "%s: setsockopt(IPPROTO_TCP TCP_NODELAY) failed: %s",
                                       __func__,
                                       strerror(ERRNO));
                        }
                }

                if (ctx && ctx->config[REQUEST_TIMEOUT]) {
                        timeout = atoi(ctx->config[REQUEST_TIMEOUT]);
                } else {
                        timeout = -1;
                }

                /* Set socket timeout to the given value, but not more than a
                 * a certain limit (SOCKET_TIMEOUT_QUANTUM, default 10 seconds),
                 * so the server can exit after that time if requested. */
                if ((timeout > 0) && (timeout < SOCKET_TIMEOUT_QUANTUM)) {
                        set_sock_timeout(so.sock, timeout);
                } else {
                        set_sock_timeout(so.sock, SOCKET_TIMEOUT_QUANTUM);
                }

                produce_socket(ctx, &so);
        }
}


static void
master_thread_run(void *thread_func_param)
{
        struct mg_context *ctx = (struct mg_context *)thread_func_param;
        struct mg_workerTLS tls;
        struct pollfd *pfd;
        unsigned int i;
        unsigned int workerthreadcount;

        if (!ctx) {
                return;
        }

        mg_set_thread_name("master");

/* Increase priority of the master thread */
#if defined(_WIN32)
        SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_ABOVE_NORMAL);
#elif defined(USE_MASTER_THREAD_PRIORITY)
        int min_prio = sched_get_priority_min(SCHED_RR);
        int max_prio = sched_get_priority_max(SCHED_RR);
        if ((min_prio >= 0) && (max_prio >= 0)
            && ((USE_MASTER_THREAD_PRIORITY) <= max_prio)
            && ((USE_MASTER_THREAD_PRIORITY) >= min_prio)) {
                struct sched_param sched_param = {0};
                sched_param.sched_priority = (USE_MASTER_THREAD_PRIORITY);
                pthread_setschedparam(pthread_self(), SCHED_RR, &sched_param);
        }
#endif

/* Initialize thread local storage */
#if defined(_WIN32) && !defined(__SYMBIAN32__)
        tls.pthread_cond_helper_mutex = CreateEvent(NULL, FALSE, FALSE, NULL);
#endif
        tls.is_master = 1;
        pthread_setspecific(sTlsKey, &tls);

        if (ctx->callbacks.init_thread) {
                /* Callback for the master thread (type 0) */
                ctx->callbacks.init_thread(ctx, 0);
        }

        /* Server starts *now* */
        ctx->start_time = time(NULL);

        /* Allocate memory for the listening sockets, and start the server */
        pfd =
            (struct pollfd *)mg_calloc(ctx->num_listening_sockets, sizeof(pfd[0]));
        while (pfd != NULL && ctx->stop_flag == 0) {
                for (i = 0; i < ctx->num_listening_sockets; i++) {
                        pfd[i].fd = ctx->listening_sockets[i].sock;
                        pfd[i].events = POLLIN;
                }

                if (poll(pfd, ctx->num_listening_sockets, 200) > 0) {
                        for (i = 0; i < ctx->num_listening_sockets; i++) {
                                /* NOTE(lsm): on QNX, poll() returns POLLRDNORM after the
                                 * successful poll, and POLLIN is defined as
                                 * (POLLRDNORM | POLLRDBAND)
                                 * Therefore, we're checking pfd[i].revents & POLLIN, not
                                 * pfd[i].revents == POLLIN. */
                                if (ctx->stop_flag == 0 && (pfd[i].revents & POLLIN)) {
                                        accept_new_connection(&ctx->listening_sockets[i], ctx);
                                }
                        }
                }
        }
        mg_free(pfd);
        DEBUG_TRACE("%s", "stopping workers");

        /* Stop signal received: somebody called mg_stop. Quit. */
        close_all_listening_sockets(ctx);

        /* Wakeup workers that are waiting for connections to handle. */
        pthread_cond_broadcast(&ctx->sq_full);

        /* Wait until all threads finish */
        (void)pthread_mutex_lock(&ctx->thread_mutex);
        while (ctx->running_worker_threads > 0) {
                (void)pthread_cond_wait(&ctx->thread_cond, &ctx->thread_mutex);
        }
        (void)pthread_mutex_unlock(&ctx->thread_mutex);

        /* Join all worker threads to avoid leaking threads. */
        workerthreadcount = ctx->cfg_worker_threads;
        for (i = 0; i < workerthreadcount; i++) {
                if (ctx->workerthreadids[i] != 0) {
                        mg_join_thread(ctx->workerthreadids[i]);
                }
        }

#if !defined(NO_SSL)
        if (ctx->ssl_ctx != NULL) {
                uninitialize_ssl(ctx);
        }
#endif
        DEBUG_TRACE("%s", "exiting");

#if defined(_WIN32) && !defined(__SYMBIAN32__)
        CloseHandle(tls.pthread_cond_helper_mutex);
#endif
        pthread_setspecific(sTlsKey, NULL);

        /* Signal mg_stop() that we're done.
         * WARNING: This must be the very last thing this
         * thread does, as ctx becomes invalid after this line. */
        ctx->stop_flag = 2;
}


/* Threads have different return types on Windows and Unix. */
#ifdef _WIN32
static unsigned __stdcall master_thread(void *thread_func_param)
{
        master_thread_run(thread_func_param);
        return 0;
}
#else
static void *
master_thread(void *thread_func_param)
{
        master_thread_run(thread_func_param);
        return NULL;
}
#endif /* _WIN32 */


static void
free_context(struct mg_context *ctx)
{
        int i;
        struct mg_handler_info *tmp_rh;

        if (ctx == NULL) {
                return;
        }

        if (ctx->callbacks.exit_context) {
                ctx->callbacks.exit_context(ctx);
        }

        /* All threads exited, no sync is needed. Destroy thread mutex and
         * condvars
         */
        (void)pthread_mutex_destroy(&ctx->thread_mutex);
        (void)pthread_cond_destroy(&ctx->thread_cond);
        (void)pthread_cond_destroy(&ctx->sq_empty);
        (void)pthread_cond_destroy(&ctx->sq_full);

        /* Destroy other context global data structures mutex */
        (void)pthread_mutex_destroy(&ctx->nonce_mutex);

#if defined(USE_TIMERS)
        timers_exit(ctx);
#endif

        /* Deallocate config parameters */
        for (i = 0; i < NUM_OPTIONS; i++) {
                if (ctx->config[i] != NULL) {
#if defined(_MSC_VER)
#pragma warning(suppress : 6001)
#endif
                        mg_free(ctx->config[i]);
                }
        }

        /* Deallocate request handlers */
        while (ctx->handlers) {
                tmp_rh = ctx->handlers;
                ctx->handlers = tmp_rh->next;
                mg_free(tmp_rh->uri);
                mg_free(tmp_rh);
        }

#ifndef NO_SSL
        /* Deallocate SSL context */
        if (ctx->ssl_ctx != NULL) {
                SSL_CTX_free(ctx->ssl_ctx);
        }
#endif /* !NO_SSL */

        /* Deallocate worker thread ID array */
        if (ctx->workerthreadids != NULL) {
                mg_free(ctx->workerthreadids);
        }

        /* Deallocate the tls variable */
        if (mg_atomic_dec(&sTlsInit) == 0) {
#if defined(_WIN32) && !defined(__SYMBIAN32__)
                DeleteCriticalSection(&global_log_file_lock);
#endif /* _WIN32 && !__SYMBIAN32__ */
#if !defined(_WIN32)
                pthread_mutexattr_destroy(&pthread_mutex_attr);
#endif

                pthread_key_delete(sTlsKey);
        }

        /* deallocate system name string */
        mg_free(ctx->systemName);

        /* Deallocate context itself */
        mg_free(ctx);
}


void
mg_stop(struct mg_context *ctx)
{
        pthread_t mt;
        if (!ctx) {
                return;
        }

        /* We don't use a lock here. Calling mg_stop with the same ctx from
         * two threads is not allowed. */
        mt = ctx->masterthreadid;
        if (mt == 0) {
                return;
        }

        ctx->masterthreadid = 0;
        ctx->stop_flag = 1;

        /* Wait until mg_fini() stops */
        while (ctx->stop_flag != 2) {
                (void)mg_sleep(10);
        }

        mg_join_thread(mt);
        free_context(ctx);

#if defined(_WIN32) && !defined(__SYMBIAN32__)
        (void)WSACleanup();
#endif /* _WIN32 && !__SYMBIAN32__ */
}


static void
get_system_name(char **sysName)
{
#if defined(_WIN32)
#if !defined(__SYMBIAN32__)
        char name[128];
        DWORD dwVersion = 0;
        DWORD dwMajorVersion = 0;
        DWORD dwMinorVersion = 0;
        DWORD dwBuild = 0;

#ifdef _MSC_VER
#pragma warning(push)
// GetVersion was declared deprecated
#pragma warning(disable : 4996)
#endif
        dwVersion = GetVersion();
#ifdef _MSC_VER
#pragma warning(pop)
#endif

        dwMajorVersion = (DWORD)(LOBYTE(LOWORD(dwVersion)));
        dwMinorVersion = (DWORD)(HIBYTE(LOWORD(dwVersion)));
        dwBuild = ((dwVersion < 0x80000000) ? (DWORD)(HIWORD(dwVersion)) : 0);
        (void)dwBuild;

        sprintf(name,
                "Windows %u.%u",
                (unsigned)dwMajorVersion,
                (unsigned)dwMinorVersion);
        *sysName = mg_strdup(name);
#else
        *sysName = mg_strdup("Symbian");
#endif
#else
        struct utsname name;
        memset(&name, 0, sizeof(name));
        uname(&name);
        *sysName = mg_strdup(name.sysname);
#endif
}


struct mg_context *
mg_start(const struct mg_callbacks *callbacks,
         void *user_data,
         const char **options)
{
        struct mg_context *ctx;
        const char *name, *value, *default_value;
        int idx, ok, workerthreadcount;
        unsigned int i;
        void (*exit_callback)(const struct mg_context *ctx) = 0;

        struct mg_workerTLS tls;

#if defined(_WIN32) && !defined(__SYMBIAN32__)
        WSADATA data;
        WSAStartup(MAKEWORD(2, 2), &data);
#endif /* _WIN32 && !__SYMBIAN32__ */

        /* Allocate context and initialize reasonable general case defaults. */
        if ((ctx = (struct mg_context *)mg_calloc(1, sizeof(*ctx))) == NULL) {
                return NULL;
        }

        /* Random number generator will initialize at the first call */
        ctx->auth_nonce_mask =
            (uint64_t)get_random() ^ (uint64_t)(ptrdiff_t)(options);

        if (mg_atomic_inc(&sTlsInit) == 1) {

#if defined(_WIN32) && !defined(__SYMBIAN32__)
                InitializeCriticalSection(&global_log_file_lock);
#endif /* _WIN32 && !__SYMBIAN32__ */
#if !defined(_WIN32)
                pthread_mutexattr_init(&pthread_mutex_attr);
                pthread_mutexattr_settype(&pthread_mutex_attr, PTHREAD_MUTEX_RECURSIVE);
#endif

                if (0 != pthread_key_create(&sTlsKey, tls_dtor)) {
                        /* Fatal error - abort start. However, this situation should
                         * never
                         * occur in practice. */
                        mg_atomic_dec(&sTlsInit);
                        mg_cry(fc(ctx), "Cannot initialize thread local storage");
                        mg_free(ctx);
                        return NULL;
                }
        } else {
                /* TODO (low): istead of sleeping, check if sTlsKey is already
                 * initialized. */
                mg_sleep(1);
        }

        tls.is_master = -1;
        tls.thread_idx = (unsigned)mg_atomic_inc(&thread_idx_max);
#if defined(_WIN32) && !defined(__SYMBIAN32__)
        tls.pthread_cond_helper_mutex = NULL;
#endif
        pthread_setspecific(sTlsKey, &tls);

#if defined(USE_LUA)
        lua_init_optional_libraries();
#endif

        ok = 0 == pthread_mutex_init(&ctx->thread_mutex, &pthread_mutex_attr);
        ok &= 0 == pthread_cond_init(&ctx->thread_cond, NULL);
        ok &= 0 == pthread_cond_init(&ctx->sq_empty, NULL);
        ok &= 0 == pthread_cond_init(&ctx->sq_full, NULL);
        ok &= 0 == pthread_mutex_init(&ctx->nonce_mutex, &pthread_mutex_attr);
        if (!ok) {
                /* Fatal error - abort start. However, this situation should never
                 * occur in practice. */
                mg_cry(fc(ctx), "Cannot initialize thread synchronization objects");
                mg_free(ctx);
                pthread_setspecific(sTlsKey, NULL);
                return NULL;
        }

        if (callbacks) {
                ctx->callbacks = *callbacks;
                exit_callback = callbacks->exit_context;
                ctx->callbacks.exit_context = 0;
        }
        ctx->user_data = user_data;
        ctx->handlers = NULL;

#if defined(USE_LUA) && defined(USE_WEBSOCKET)
        ctx->shared_lua_websockets = 0;
#endif

        while (options && (name = *options++) != NULL) {
                if ((idx = get_option_index(name)) == -1) {
                        mg_cry(fc(ctx), "Invalid option: %s", name);
                        free_context(ctx);
                        pthread_setspecific(sTlsKey, NULL);
                        return NULL;
                } else if ((value = *options++) == NULL) {
                        mg_cry(fc(ctx), "%s: option value cannot be NULL", name);
                        free_context(ctx);
                        pthread_setspecific(sTlsKey, NULL);
                        return NULL;
                }
                if (ctx->config[idx] != NULL) {
                        mg_cry(fc(ctx), "warning: %s: duplicate option", name);
                        mg_free(ctx->config[idx]);
                }
                ctx->config[idx] = mg_strdup(value);
                DEBUG_TRACE("[%s] -> [%s]", name, value);
        }

        /* Set default value if needed */
        for (i = 0; config_options[i].name != NULL; i++) {
                default_value = config_options[i].default_value;
                if (ctx->config[i] == NULL && default_value != NULL) {
                        ctx->config[i] = mg_strdup(default_value);
                }
        }

#if defined(NO_FILES)
        if (ctx->config[DOCUMENT_ROOT] != NULL) {
                mg_cry(fc(ctx), "%s", "Document root must not be set");
                free_context(ctx);
                pthread_setspecific(sTlsKey, NULL);
                return NULL;
        }
#endif

        get_system_name(&ctx->systemName);

        /* NOTE(lsm): order is important here. SSL certificates must
         * be initialized before listening ports. UID must be set last. */
        if (!set_gpass_option(ctx) ||
#if !defined(NO_SSL)
            !set_ssl_option(ctx) ||
#endif
            !set_ports_option(ctx) ||
#if !defined(_WIN32)
            !set_uid_option(ctx) ||
#endif
            !set_acl_option(ctx)) {
                free_context(ctx);
                pthread_setspecific(sTlsKey, NULL);
                return NULL;
        }

#if !defined(_WIN32) && !defined(__SYMBIAN32__)
        /* Ignore SIGPIPE signal, so if browser cancels the request, it
         * won't kill the whole process. */
        (void)signal(SIGPIPE, SIG_IGN);
#endif /* !_WIN32 && !__SYMBIAN32__ */

        workerthreadcount = atoi(ctx->config[NUM_THREADS]);

        if (workerthreadcount > MAX_WORKER_THREADS) {
                mg_cry(fc(ctx), "Too many worker threads");
                free_context(ctx);
                pthread_setspecific(sTlsKey, NULL);
                return NULL;
        }

        if (workerthreadcount > 0) {
                ctx->cfg_worker_threads = ((unsigned int)(workerthreadcount));
                ctx->workerthreadids =
                    (pthread_t *)mg_calloc(ctx->cfg_worker_threads, sizeof(pthread_t));
                if (ctx->workerthreadids == NULL) {
                        mg_cry(fc(ctx), "Not enough memory for worker thread ID array");
                        free_context(ctx);
                        pthread_setspecific(sTlsKey, NULL);
                        return NULL;
                }
        }

#if defined(USE_TIMERS)
        if (timers_init(ctx) != 0) {
                mg_cry(fc(ctx), "Error creating timers");
                free_context(ctx);
                pthread_setspecific(sTlsKey, NULL);
                return NULL;
        }
#endif

        /* Context has been created - init user libraries */
        if (ctx->callbacks.init_context) {
                ctx->callbacks.init_context(ctx);
        }
        ctx->callbacks.exit_context = exit_callback;
        ctx->context_type = 1; /* server context */

        /* Start master (listening) thread */
        mg_start_thread_with_id(master_thread, ctx, &ctx->masterthreadid);

        /* Start worker threads */
        for (i = 0; i < ctx->cfg_worker_threads; i++) {
                (void)pthread_mutex_lock(&ctx->thread_mutex);
                ctx->running_worker_threads++;
                (void)pthread_mutex_unlock(&ctx->thread_mutex);
                if (mg_start_thread_with_id(worker_thread,
                                            ctx,
                                            &ctx->workerthreadids[i]) != 0) {
                        (void)pthread_mutex_lock(&ctx->thread_mutex);
                        ctx->running_worker_threads--;
                        (void)pthread_mutex_unlock(&ctx->thread_mutex);
                        if (i > 0) {
                                mg_cry(fc(ctx),
                                       "Cannot start worker thread %i: error %ld",
                                       i + 1,
                                       (long)ERRNO);
                        } else {
                                mg_cry(fc(ctx),
                                       "Cannot create threads: error %ld",
                                       (long)ERRNO);
                                free_context(ctx);
                                pthread_setspecific(sTlsKey, NULL);
                                return NULL;
                        }
                        break;
                }
        }

        pthread_setspecific(sTlsKey, NULL);
        return ctx;
}


/* Feature check API function */
unsigned
mg_check_feature(unsigned feature)
{
        static const unsigned feature_set = 0
/* Set bits for available features according to API documentation.
 * This bit mask is created at compile time, according to the active
 * preprocessor defines. It is a single const value at runtime. */
#if !defined(NO_FILES)
                                            | 0x0001u
#endif
#if !defined(NO_SSL)
                                            | 0x0002u
#endif
#if !defined(NO_CGI)
                                            | 0x0004u
#endif
#if defined(USE_IPV6)
                                            | 0x0008u
#endif
#if defined(USE_WEBSOCKET)
                                            | 0x0010u
#endif
#if defined(USE_LUA)
                                            | 0x0020u
#endif
#if defined(USE_DUKTAPE)
                                            | 0x0040u
#endif
#if !defined(NO_CACHING)
                                            | 0x0080u
#endif

/* Set some extra bits not defined in the API documentation.
 * These bits may change without further notice. */
#if defined(MG_LEGACY_INTERFACE)
                                            | 0x8000u
#endif
#if defined(MEMORY_DEBUGGING)
                                            | 0x0100u
#endif
#if defined(USE_TIMERS)
                                            | 0x0200u
#endif
#if !defined(NO_NONCE_CHECK)
                                            | 0x0400u
#endif
#if !defined(NO_POPEN)
                                            | 0x0800u
#endif
            ;
        return (feature & feature_set);
}