New upstream version 1.5.0+ds

[libgit2.git] / src / libgit2 / transports / httpclient.c

/*
 * Copyright (C) the libgit2 contributors. All rights reserved.
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */

#include "common.h"
#include "git2.h"
#include "http_parser.h"
#include "vector.h"
#include "trace.h"
#include "httpclient.h"
#include "http.h"
#include "auth.h"
#include "auth_negotiate.h"
#include "auth_ntlm.h"
#include "git2/sys/credential.h"
#include "net.h"
#include "stream.h"
#include "streams/socket.h"
#include "streams/tls.h"
#include "auth.h"

static git_http_auth_scheme auth_schemes[] = {
        { GIT_HTTP_AUTH_NEGOTIATE, "Negotiate", GIT_CREDENTIAL_DEFAULT, git_http_auth_negotiate },
        { GIT_HTTP_AUTH_NTLM, "NTLM", GIT_CREDENTIAL_USERPASS_PLAINTEXT, git_http_auth_ntlm },
        { GIT_HTTP_AUTH_BASIC, "Basic", GIT_CREDENTIAL_USERPASS_PLAINTEXT, git_http_auth_basic },
};

/*
 * Use a 16kb read buffer to match the maximum size of a TLS packet.  This
 * is critical for compatibility with SecureTransport, which will always do
 * a network read on every call, even if it has data buffered to return to
 * you.  That buffered data may be the _end_ of a keep-alive response, so
 * if SecureTransport performs another network read, it will wait until the
 * server ultimately times out before it returns that buffered data to you.
 * Since SecureTransport only reads a single TLS packet at a time, by
 * calling it with a read buffer that is the maximum size of a TLS packet,
 * we ensure that it will never buffer.
 */
#define GIT_READ_BUFFER_SIZE (16 * 1024)

typedef struct {
        git_net_url url;
        git_stream *stream;

        git_vector auth_challenges;
        git_http_auth_context *auth_context;
} git_http_server;

typedef enum {
        PROXY = 1,
        SERVER
} git_http_server_t;

typedef enum {
        NONE = 0,
        SENDING_REQUEST,
        SENDING_BODY,
        SENT_REQUEST,
        HAS_EARLY_RESPONSE,
        READING_RESPONSE,
        READING_BODY,
        DONE
} http_client_state;

/* Parser state */
typedef enum {
        PARSE_HEADER_NONE = 0,
        PARSE_HEADER_NAME,
        PARSE_HEADER_VALUE,
        PARSE_HEADER_COMPLETE
} parse_header_state;

typedef enum {
        PARSE_STATUS_OK,
        PARSE_STATUS_NO_OUTPUT,
        PARSE_STATUS_ERROR
} parse_status;

typedef struct {
        git_http_client *client;
        git_http_response *response;

        /* Temporary buffers to avoid extra mallocs */
        git_str parse_header_name;
        git_str parse_header_value;

        /* Parser state */
        int error;
        parse_status parse_status;

        /* Headers parsing */
        parse_header_state parse_header_state;

        /* Body parsing */
        char *output_buf;       /* Caller's output buffer */
        size_t output_size;     /* Size of caller's output buffer */
        size_t output_written;  /* Bytes we've written to output buffer */
} http_parser_context;

/* HTTP client connection */
struct git_http_client {
        git_http_client_options opts;

        /* Are we writing to the proxy or server, and state of the client. */
        git_http_server_t current_server;
        http_client_state state;

        http_parser parser;

        git_http_server server;
        git_http_server proxy;

        unsigned request_count;
        unsigned connected : 1,
                 proxy_connected : 1,
                 keepalive : 1,
                 request_chunked : 1;

        /* Temporary buffers to avoid extra mallocs */
        git_str request_msg;
        git_str read_buf;

        /* A subset of information from the request */
        size_t request_body_len,
               request_body_remain;

        /*
         * When state == HAS_EARLY_RESPONSE, the response of our proxy
         * that we have buffered and will deliver during read_response.
         */
        git_http_response early_response;
};

bool git_http_response_is_redirect(git_http_response *response)
{
        return (response->status == GIT_HTTP_MOVED_PERMANENTLY ||
                response->status == GIT_HTTP_FOUND ||
                response->status == GIT_HTTP_SEE_OTHER ||
                response->status == GIT_HTTP_TEMPORARY_REDIRECT ||
                response->status == GIT_HTTP_PERMANENT_REDIRECT);
}

void git_http_response_dispose(git_http_response *response)
{
        if (!response)
                return;

        git__free(response->content_type);
        git__free(response->location);

        memset(response, 0, sizeof(git_http_response));
}

static int on_header_complete(http_parser *parser)
{
        http_parser_context *ctx = (http_parser_context *) parser->data;
        git_http_client *client = ctx->client;
        git_http_response *response = ctx->response;

        git_str *name = &ctx->parse_header_name;
        git_str *value = &ctx->parse_header_value;

        if (!strcasecmp("Content-Type", name->ptr)) {
                if (response->content_type) {
                        git_error_set(GIT_ERROR_HTTP,
                                      "multiple content-type headers");
                        return -1;
                }

                response->content_type =
                        git__strndup(value->ptr, value->size);
                GIT_ERROR_CHECK_ALLOC(ctx->response->content_type);
        } else if (!strcasecmp("Content-Length", name->ptr)) {
                int64_t len;

                if (response->content_length) {
                        git_error_set(GIT_ERROR_HTTP,
                                      "multiple content-length headers");
                        return -1;
                }

                if (git__strntol64(&len, value->ptr, value->size,
                                   NULL, 10) < 0 || len < 0) {
                        git_error_set(GIT_ERROR_HTTP,
                                      "invalid content-length");
                        return -1;
                }

                response->content_length = (size_t)len;
        } else if (!strcasecmp("Transfer-Encoding", name->ptr) &&
                   !strcasecmp("chunked", value->ptr)) {
                        ctx->response->chunked = 1;
        } else if (!strcasecmp("Proxy-Authenticate", git_str_cstr(name))) {
                char *dup = git__strndup(value->ptr, value->size);
                GIT_ERROR_CHECK_ALLOC(dup);

                if (git_vector_insert(&client->proxy.auth_challenges, dup) < 0)
                        return -1;
        } else if (!strcasecmp("WWW-Authenticate", name->ptr)) {
                char *dup = git__strndup(value->ptr, value->size);
                GIT_ERROR_CHECK_ALLOC(dup);

                if (git_vector_insert(&client->server.auth_challenges, dup) < 0)
                        return -1;
        } else if (!strcasecmp("Location", name->ptr)) {
                if (response->location) {
                        git_error_set(GIT_ERROR_HTTP,
                                "multiple location headers");
                        return -1;
                }

                response->location = git__strndup(value->ptr, value->size);
                GIT_ERROR_CHECK_ALLOC(response->location);
        }

        return 0;
}

static int on_header_field(http_parser *parser, const char *str, size_t len)
{
        http_parser_context *ctx = (http_parser_context *) parser->data;

        switch (ctx->parse_header_state) {
        /*
         * We last saw a header value, process the name/value pair and
         * get ready to handle this new name.
         */
        case PARSE_HEADER_VALUE:
                if (on_header_complete(parser) < 0)
                        return ctx->parse_status = PARSE_STATUS_ERROR;

                git_str_clear(&ctx->parse_header_name);
                git_str_clear(&ctx->parse_header_value);
                /* Fall through */

        case PARSE_HEADER_NONE:
        case PARSE_HEADER_NAME:
                ctx->parse_header_state = PARSE_HEADER_NAME;

                if (git_str_put(&ctx->parse_header_name, str, len) < 0)
                        return ctx->parse_status = PARSE_STATUS_ERROR;

                break;

        default:
                git_error_set(GIT_ERROR_HTTP,
                              "header name seen at unexpected time");
                return ctx->parse_status = PARSE_STATUS_ERROR;
        }

        return 0;
}

static int on_header_value(http_parser *parser, const char *str, size_t len)
{
        http_parser_context *ctx = (http_parser_context *) parser->data;

        switch (ctx->parse_header_state) {
        case PARSE_HEADER_NAME:
        case PARSE_HEADER_VALUE:
                ctx->parse_header_state = PARSE_HEADER_VALUE;

                if (git_str_put(&ctx->parse_header_value, str, len) < 0)
                        return ctx->parse_status = PARSE_STATUS_ERROR;

                break;

        default:
                git_error_set(GIT_ERROR_HTTP,
                              "header value seen at unexpected time");
                return ctx->parse_status = PARSE_STATUS_ERROR;
        }

        return 0;
}

GIT_INLINE(bool) challenge_matches_scheme(
        const char *challenge,
        git_http_auth_scheme *scheme)
{
        const char *scheme_name = scheme->name;
        size_t scheme_len = strlen(scheme_name);

        if (!strncasecmp(challenge, scheme_name, scheme_len) &&
            (challenge[scheme_len] == '\0' || challenge[scheme_len] == ' '))
                return true;

        return false;
}

static git_http_auth_scheme *scheme_for_challenge(const char *challenge)
{
        size_t i;

        for (i = 0; i < ARRAY_SIZE(auth_schemes); i++) {
                if (challenge_matches_scheme(challenge, &auth_schemes[i]))
                        return &auth_schemes[i];
        }

        return NULL;
}

GIT_INLINE(void) collect_authinfo(
        unsigned int *schemetypes,
        unsigned int *credtypes,
        git_vector *challenges)
{
        git_http_auth_scheme *scheme;
        const char *challenge;
        size_t i;

        *schemetypes = 0;
        *credtypes = 0;

        git_vector_foreach(challenges, i, challenge) {
                if ((scheme = scheme_for_challenge(challenge)) != NULL) {
                        *schemetypes |= scheme->type;
                        *credtypes |= scheme->credtypes;
                }
        }
}

static int resend_needed(git_http_client *client, git_http_response *response)
{
        git_http_auth_context *auth_context;

        if (response->status == GIT_HTTP_STATUS_UNAUTHORIZED &&
            (auth_context = client->server.auth_context) &&
            auth_context->is_complete &&
            !auth_context->is_complete(auth_context))
                return 1;

        if (response->status == GIT_HTTP_STATUS_PROXY_AUTHENTICATION_REQUIRED &&
            (auth_context = client->proxy.auth_context) &&
            auth_context->is_complete &&
            !auth_context->is_complete(auth_context))
                return 1;

        return 0;
}

static int on_headers_complete(http_parser *parser)
{
        http_parser_context *ctx = (http_parser_context *) parser->data;

        /* Finalize the last seen header */
        switch (ctx->parse_header_state) {
        case PARSE_HEADER_VALUE:
                if (on_header_complete(parser) < 0)
                        return ctx->parse_status = PARSE_STATUS_ERROR;

                /* Fall through */

        case PARSE_HEADER_NONE:
                ctx->parse_header_state = PARSE_HEADER_COMPLETE;
                break;

        default:
                git_error_set(GIT_ERROR_HTTP,
                              "header completion at unexpected time");
                return ctx->parse_status = PARSE_STATUS_ERROR;
        }

        ctx->response->status = parser->status_code;
        ctx->client->keepalive = http_should_keep_alive(parser);

        /* Prepare for authentication */
        collect_authinfo(&ctx->response->server_auth_schemetypes,
                         &ctx->response->server_auth_credtypes,
                         &ctx->client->server.auth_challenges);
        collect_authinfo(&ctx->response->proxy_auth_schemetypes,
                         &ctx->response->proxy_auth_credtypes,
                         &ctx->client->proxy.auth_challenges);

        ctx->response->resend_credentials = resend_needed(ctx->client,
                                                          ctx->response);

        /* Stop parsing. */
        http_parser_pause(parser, 1);

        if (ctx->response->content_type || ctx->response->chunked)
                ctx->client->state = READING_BODY;
        else
                ctx->client->state = DONE;

        return 0;
}

static int on_body(http_parser *parser, const char *buf, size_t len)
{
        http_parser_context *ctx = (http_parser_context *) parser->data;
        size_t max_len;

        /* Saw data when we expected not to (eg, in consume_response_body) */
        if (ctx->output_buf == NULL || ctx->output_size == 0) {
                ctx->parse_status = PARSE_STATUS_NO_OUTPUT;
                return 0;
        }

        GIT_ASSERT(ctx->output_size >= ctx->output_written);

        max_len = min(ctx->output_size - ctx->output_written, len);
        max_len = min(max_len, INT_MAX);

        memcpy(ctx->output_buf + ctx->output_written, buf, max_len);
        ctx->output_written += max_len;

        return 0;
}

static int on_message_complete(http_parser *parser)
{
        http_parser_context *ctx = (http_parser_context *) parser->data;

        ctx->client->state = DONE;
        return 0;
}

GIT_INLINE(int) stream_write(
        git_http_server *server,
        const char *data,
        size_t len)
{
        git_trace(GIT_TRACE_TRACE,
                  "Sending request:\n%.*s", (int)len, data);

        return git_stream__write_full(server->stream, data, len, 0);
}

GIT_INLINE(int) client_write_request(git_http_client *client)
{
        git_stream *stream = client->current_server == PROXY ?
                             client->proxy.stream : client->server.stream;

        git_trace(GIT_TRACE_TRACE,
                  "Sending request:\n%.*s",
                  (int)client->request_msg.size, client->request_msg.ptr);

        return git_stream__write_full(stream,
                                      client->request_msg.ptr,
                                      client->request_msg.size,
                                      0);
}

static const char *name_for_method(git_http_method method)
{
        switch (method) {
        case GIT_HTTP_METHOD_GET:
                return "GET";
        case GIT_HTTP_METHOD_POST:
                return "POST";
        case GIT_HTTP_METHOD_CONNECT:
                return "CONNECT";
        }

        return NULL;
}

/*
 * Find the scheme that is suitable for the given credentials, based on the
 * server's auth challenges.
 */
static bool best_scheme_and_challenge(
        git_http_auth_scheme **scheme_out,
        const char **challenge_out,
        git_vector *challenges,
        git_credential *credentials)
{
        const char *challenge;
        size_t i, j;

        for (i = 0; i < ARRAY_SIZE(auth_schemes); i++) {
                git_vector_foreach(challenges, j, challenge) {
                        git_http_auth_scheme *scheme = &auth_schemes[i];

                        if (challenge_matches_scheme(challenge, scheme) &&
                            (scheme->credtypes & credentials->credtype)) {
                                *scheme_out = scheme;
                                *challenge_out = challenge;
                                return true;
                        }
                }
        }

        return false;
}

/*
 * Find the challenge from the server for our current auth context.
 */
static const char *challenge_for_context(
        git_vector *challenges,
        git_http_auth_context *auth_ctx)
{
        const char *challenge;
        size_t i, j;

        for (i = 0; i < ARRAY_SIZE(auth_schemes); i++) {
                if (auth_schemes[i].type == auth_ctx->type) {
                        git_http_auth_scheme *scheme = &auth_schemes[i];

                        git_vector_foreach(challenges, j, challenge) {
                                if (challenge_matches_scheme(challenge, scheme))
                                        return challenge;
                        }
                }
        }

        return NULL;
}

static const char *init_auth_context(
        git_http_server *server,
        git_vector *challenges,
        git_credential *credentials)
{
        git_http_auth_scheme *scheme;
        const char *challenge;
        int error;

        if (!best_scheme_and_challenge(&scheme, &challenge, challenges, credentials)) {
                git_error_set(GIT_ERROR_HTTP, "could not find appropriate mechanism for credentials");
                return NULL;
        }

        error = scheme->init_context(&server->auth_context, &server->url);

        if (error == GIT_PASSTHROUGH) {
                git_error_set(GIT_ERROR_HTTP, "'%s' authentication is not supported", scheme->name);
                return NULL;
        }

        return challenge;
}

static void free_auth_context(git_http_server *server)
{
        if (!server->auth_context)
                return;

        if (server->auth_context->free)
                server->auth_context->free(server->auth_context);

        server->auth_context = NULL;
}

static int apply_credentials(
        git_str *buf,
        git_http_server *server,
        const char *header_name,
        git_credential *credentials)
{
        git_http_auth_context *auth = server->auth_context;
        git_vector *challenges = &server->auth_challenges;
        const char *challenge;
        git_str token = GIT_STR_INIT;
        int error = 0;

        /* We've started a new request without creds; free the context. */
        if (auth && !credentials) {
                free_auth_context(server);
                return 0;
        }

        /* We haven't authenticated, nor were we asked to.  Nothing to do. */
        if (!auth && !git_vector_length(challenges))
                return 0;

        if (!auth) {
                challenge = init_auth_context(server, challenges, credentials);
                auth = server->auth_context;

                if (!challenge || !auth) {
                        error = -1;
                        goto done;
                }
        } else if (auth->set_challenge) {
                challenge = challenge_for_context(challenges, auth);
        }

        if (auth->set_challenge && challenge &&
            (error = auth->set_challenge(auth, challenge)) < 0)
                goto done;

        if ((error = auth->next_token(&token, auth, credentials)) < 0)
                goto done;

        if (auth->is_complete && auth->is_complete(auth)) {
                /*
                 * If we're done with an auth mechanism with connection affinity,
                 * we don't need to send any more headers and can dispose the context.
                 */
                if (auth->connection_affinity)
                        free_auth_context(server);
        } else if (!token.size) {
                git_error_set(GIT_ERROR_HTTP, "failed to respond to authentication challenge");
                error = GIT_EAUTH;
                goto done;
        }

        if (token.size > 0)
                error = git_str_printf(buf, "%s: %s\r\n", header_name, token.ptr);

done:
        git_str_dispose(&token);
        return error;
}

GIT_INLINE(int) apply_server_credentials(
        git_str *buf,
        git_http_client *client,
        git_http_request *request)
{
        return apply_credentials(buf,
                                 &client->server,
                                 "Authorization",
                                 request->credentials);
}

GIT_INLINE(int) apply_proxy_credentials(
        git_str *buf,
        git_http_client *client,
        git_http_request *request)
{
        return apply_credentials(buf,
                                 &client->proxy,
                                 "Proxy-Authorization",
                                 request->proxy_credentials);
}

static int puts_host_and_port(git_str *buf, git_net_url *url, bool force_port)
{
        bool ipv6 = git_net_url_is_ipv6(url);

        if (ipv6)
                git_str_putc(buf, '[');

        git_str_puts(buf, url->host);

        if (ipv6)
                git_str_putc(buf, ']');

        if (force_port || !git_net_url_is_default_port(url)) {
                git_str_putc(buf, ':');
                git_str_puts(buf, url->port);
        }

        return git_str_oom(buf) ? -1 : 0;
}

static int generate_connect_request(
        git_http_client *client,
        git_http_request *request)
{
        git_str *buf;
        int error;

        git_str_clear(&client->request_msg);
        buf = &client->request_msg;

        git_str_puts(buf, "CONNECT ");
        puts_host_and_port(buf, &client->server.url, true);
        git_str_puts(buf, " HTTP/1.1\r\n");

        git_str_puts(buf, "User-Agent: ");
        git_http__user_agent(buf);
        git_str_puts(buf, "\r\n");

        git_str_puts(buf, "Host: ");
        puts_host_and_port(buf, &client->server.url, true);
        git_str_puts(buf, "\r\n");

        if ((error = apply_proxy_credentials(buf, client, request) < 0))
                return -1;

        git_str_puts(buf, "\r\n");

        return git_str_oom(buf) ? -1 : 0;
}

static bool use_connect_proxy(git_http_client *client)
{
    return client->proxy.url.host && !strcmp(client->server.url.scheme, "https");
}

static int generate_request(
        git_http_client *client,
        git_http_request *request)
{
        git_str *buf;
        size_t i;
        int error;

        GIT_ASSERT_ARG(client);
        GIT_ASSERT_ARG(request);

        git_str_clear(&client->request_msg);
        buf = &client->request_msg;

        /* GET|POST path HTTP/1.1 */
        git_str_puts(buf, name_for_method(request->method));
        git_str_putc(buf, ' ');

        if (request->proxy && strcmp(request->url->scheme, "https"))
                git_net_url_fmt(buf, request->url);
        else
                git_net_url_fmt_path(buf, request->url);

        git_str_puts(buf, " HTTP/1.1\r\n");

        git_str_puts(buf, "User-Agent: ");
        git_http__user_agent(buf);
        git_str_puts(buf, "\r\n");

        git_str_puts(buf, "Host: ");
        puts_host_and_port(buf, request->url, false);
        git_str_puts(buf, "\r\n");

        if (request->accept)
                git_str_printf(buf, "Accept: %s\r\n", request->accept);
        else
                git_str_puts(buf, "Accept: */*\r\n");

        if (request->content_type)
                git_str_printf(buf, "Content-Type: %s\r\n",
                        request->content_type);

        if (request->chunked)
                git_str_puts(buf, "Transfer-Encoding: chunked\r\n");

        if (request->content_length > 0)
                git_str_printf(buf, "Content-Length: %"PRIuZ "\r\n",
                        request->content_length);

        if (request->expect_continue)
                git_str_printf(buf, "Expect: 100-continue\r\n");

        if ((error = apply_server_credentials(buf, client, request)) < 0 ||
            (!use_connect_proxy(client) &&
                        (error = apply_proxy_credentials(buf, client, request)) < 0))
                return error;

        if (request->custom_headers) {
                for (i = 0; i < request->custom_headers->count; i++) {
                        const char *hdr = request->custom_headers->strings[i];

                        if (hdr)
                                git_str_printf(buf, "%s\r\n", hdr);
                }
        }

        git_str_puts(buf, "\r\n");

        if (git_str_oom(buf))
                return -1;

        return 0;
}

static int check_certificate(
        git_stream *stream,
        git_net_url *url,
        int is_valid,
        git_transport_certificate_check_cb cert_cb,
        void *cert_cb_payload)
{
        git_cert *cert;
        git_error_state last_error = {0};
        int error;

        if ((error = git_stream_certificate(&cert, stream)) < 0)
                return error;

        git_error_state_capture(&last_error, GIT_ECERTIFICATE);

        error = cert_cb(cert, is_valid, url->host, cert_cb_payload);

        if (error == GIT_PASSTHROUGH && !is_valid)
                return git_error_state_restore(&last_error);
        else if (error == GIT_PASSTHROUGH)
                error = 0;
        else if (error && !git_error_last())
                git_error_set(GIT_ERROR_HTTP,
                              "user rejected certificate for %s", url->host);

        git_error_state_free(&last_error);
        return error;
}

static int server_connect_stream(
        git_http_server *server,
        git_transport_certificate_check_cb cert_cb,
        void *cb_payload)
{
        int error;

        GIT_ERROR_CHECK_VERSION(server->stream, GIT_STREAM_VERSION, "git_stream");

        error = git_stream_connect(server->stream);

        if (error && error != GIT_ECERTIFICATE)
                return error;

        if (git_stream_is_encrypted(server->stream) && cert_cb != NULL)
                error = check_certificate(server->stream, &server->url, !error,
                                          cert_cb, cb_payload);

        return error;
}

static void reset_auth_connection(git_http_server *server)
{
        /*
         * If we've authenticated and we're doing "normal"
         * authentication with a request affinity (Basic, Digest)
         * then we want to _keep_ our context, since authentication
         * survives even through non-keep-alive connections.  If
         * we've authenticated and we're doing connection-based
         * authentication (NTLM, Negotiate) - indicated by the presence
         * of an `is_complete` callback - then we need to restart
         * authentication on a new connection.
         */

        if (server->auth_context &&
            server->auth_context->connection_affinity)
                free_auth_context(server);
}

/*
 * Updates the server data structure with the new URL; returns 1 if the server
 * has changed and we need to reconnect, returns 0 otherwise.
 */
GIT_INLINE(int) server_setup_from_url(
        git_http_server *server,
        git_net_url *url)
{
        if (!server->url.scheme || strcmp(server->url.scheme, url->scheme) ||
            !server->url.host || strcmp(server->url.host, url->host) ||
            !server->url.port || strcmp(server->url.port, url->port)) {
                git__free(server->url.scheme);
                git__free(server->url.host);
                git__free(server->url.port);

                server->url.scheme = git__strdup(url->scheme);
                GIT_ERROR_CHECK_ALLOC(server->url.scheme);

                server->url.host = git__strdup(url->host);
                GIT_ERROR_CHECK_ALLOC(server->url.host);

                server->url.port = git__strdup(url->port);
                GIT_ERROR_CHECK_ALLOC(server->url.port);

                return 1;
        }

        return 0;
}

static void reset_parser(git_http_client *client)
{
        http_parser_init(&client->parser, HTTP_RESPONSE);
}

static int setup_hosts(
        git_http_client *client,
        git_http_request *request)
{
        int ret, diff = 0;

        GIT_ASSERT_ARG(client);
        GIT_ASSERT_ARG(request);

        GIT_ASSERT(request->url);

        if ((ret = server_setup_from_url(&client->server, request->url)) < 0)
                return ret;

        diff |= ret;

        if (request->proxy &&
            (ret = server_setup_from_url(&client->proxy, request->proxy)) < 0)
                return ret;

        diff |= ret;

        if (diff) {
                free_auth_context(&client->server);
                free_auth_context(&client->proxy);

                client->connected = 0;
        }

        return 0;
}

GIT_INLINE(int) server_create_stream(git_http_server *server)
{
        git_net_url *url = &server->url;

        if (strcasecmp(url->scheme, "https") == 0)
                return git_tls_stream_new(&server->stream, url->host, url->port);
        else if (strcasecmp(url->scheme, "http") == 0)
                return git_socket_stream_new(&server->stream, url->host, url->port);

        git_error_set(GIT_ERROR_HTTP, "unknown http scheme '%s'", url->scheme);
        return -1;
}

GIT_INLINE(void) save_early_response(
        git_http_client *client,
        git_http_response *response)
{
        /* Buffer the response so we can return it in read_response */
        client->state = HAS_EARLY_RESPONSE;

        memcpy(&client->early_response, response, sizeof(git_http_response));
        memset(response, 0, sizeof(git_http_response));
}

static int proxy_connect(
        git_http_client *client,
        git_http_request *request)
{
        git_http_response response = {0};
        int error;

        if (!client->proxy_connected || !client->keepalive) {
                git_trace(GIT_TRACE_DEBUG, "Connecting to proxy %s port %s",
                          client->proxy.url.host, client->proxy.url.port);

                if ((error = server_create_stream(&client->proxy)) < 0 ||
                    (error = server_connect_stream(&client->proxy,
                        client->opts.proxy_certificate_check_cb,
                        client->opts.proxy_certificate_check_payload)) < 0)
                        goto done;

                client->proxy_connected = 1;
        }

        client->current_server = PROXY;
        client->state = SENDING_REQUEST;

        if ((error = generate_connect_request(client, request)) < 0 ||
            (error = client_write_request(client)) < 0)
                goto done;

        client->state = SENT_REQUEST;

        if ((error = git_http_client_read_response(&response, client)) < 0 ||
            (error = git_http_client_skip_body(client)) < 0)
                goto done;

        GIT_ASSERT(client->state == DONE);

        if (response.status == GIT_HTTP_STATUS_PROXY_AUTHENTICATION_REQUIRED) {
                save_early_response(client, &response);

                error = GIT_RETRY;
                goto done;
        } else if (response.status != GIT_HTTP_STATUS_OK) {
                git_error_set(GIT_ERROR_HTTP, "proxy returned unexpected status: %d", response.status);
                error = -1;
                goto done;
        }

        reset_parser(client);
        client->state = NONE;

done:
        git_http_response_dispose(&response);
        return error;
}

static int server_connect(git_http_client *client)
{
        git_net_url *url = &client->server.url;
        git_transport_certificate_check_cb cert_cb;
        void *cert_payload;
        int error;

        client->current_server = SERVER;

        if (client->proxy.stream)
                error = git_tls_stream_wrap(&client->server.stream, client->proxy.stream, url->host);
        else
                error = server_create_stream(&client->server);

        if (error < 0)
                goto done;

        cert_cb = client->opts.server_certificate_check_cb;
        cert_payload = client->opts.server_certificate_check_payload;

        error = server_connect_stream(&client->server, cert_cb, cert_payload);

done:
        return error;
}

GIT_INLINE(void) close_stream(git_http_server *server)
{
        if (server->stream) {
                git_stream_close(server->stream);
                git_stream_free(server->stream);
                server->stream = NULL;
        }
}

static int http_client_connect(
        git_http_client *client,
        git_http_request *request)
{
        bool use_proxy = false;
        int error;

        if ((error = setup_hosts(client, request)) < 0)
                goto on_error;

        /* We're connected to our destination server; no need to reconnect */
        if (client->connected && client->keepalive &&
            (client->state == NONE || client->state == DONE))
                return 0;

        client->connected = 0;
        client->request_count = 0;

        close_stream(&client->server);
        reset_auth_connection(&client->server);

        reset_parser(client);

        /* Reconnect to the proxy if necessary. */
        use_proxy = use_connect_proxy(client);

        if (use_proxy) {
                if (!client->proxy_connected || !client->keepalive ||
                    (client->state != NONE && client->state != DONE)) {
                        close_stream(&client->proxy);
                        reset_auth_connection(&client->proxy);

                        client->proxy_connected = 0;
                }

                if ((error = proxy_connect(client, request)) < 0)
                        goto on_error;
        }

        git_trace(GIT_TRACE_DEBUG, "Connecting to remote %s port %s",
                  client->server.url.host, client->server.url.port);

        if ((error = server_connect(client)) < 0)
                goto on_error;

        client->connected = 1;
        return error;

on_error:
        if (error != GIT_RETRY)
                close_stream(&client->proxy);

        close_stream(&client->server);
        return error;
}

GIT_INLINE(int) client_read(git_http_client *client)
{
        http_parser_context *parser_context = client->parser.data;
        git_stream *stream;
        char *buf = client->read_buf.ptr + client->read_buf.size;
        size_t max_len;
        ssize_t read_len;

        stream = client->current_server == PROXY ?
                client->proxy.stream : client->server.stream;

        /*
         * We use a git_str for convenience, but statically allocate it and
         * don't resize.  Limit our consumption to INT_MAX since calling
         * functions use an int return type to return number of bytes read.
         */
        max_len = client->read_buf.asize - client->read_buf.size;
        max_len = min(max_len, INT_MAX);

        if (parser_context->output_size)
                max_len = min(max_len, parser_context->output_size);

        if (max_len == 0) {
                git_error_set(GIT_ERROR_HTTP, "no room in output buffer");
                return -1;
        }

        read_len = git_stream_read(stream, buf, max_len);

        if (read_len >= 0) {
                client->read_buf.size += read_len;

                git_trace(GIT_TRACE_TRACE, "Received:\n%.*s",
                          (int)read_len, buf);
        }

        return (int)read_len;
}

static bool parser_settings_initialized;
static http_parser_settings parser_settings;

GIT_INLINE(http_parser_settings *) http_client_parser_settings(void)
{
        if (!parser_settings_initialized) {
                parser_settings.on_header_field = on_header_field;
                parser_settings.on_header_value = on_header_value;
                parser_settings.on_headers_complete = on_headers_complete;
                parser_settings.on_body = on_body;
                parser_settings.on_message_complete = on_message_complete;

                parser_settings_initialized = true;
        }

        return &parser_settings;
}

GIT_INLINE(int) client_read_and_parse(git_http_client *client)
{
        http_parser *parser = &client->parser;
        http_parser_context *ctx = (http_parser_context *) parser->data;
        unsigned char http_errno;
        int read_len;
        size_t parsed_len;

        /*
         * If we have data in our read buffer, that means we stopped early
         * when parsing headers.  Use the data in the read buffer instead of
         * reading more from the socket.
         */
        if (!client->read_buf.size && (read_len = client_read(client)) < 0)
                return read_len;

        parsed_len = http_parser_execute(parser,
                http_client_parser_settings(),
                client->read_buf.ptr,
                client->read_buf.size);
        http_errno = client->parser.http_errno;

        if (parsed_len > INT_MAX) {
                git_error_set(GIT_ERROR_HTTP, "unexpectedly large parse");
                return -1;
        }

        if (ctx->parse_status == PARSE_STATUS_ERROR) {
                client->connected = 0;
                return ctx->error ? ctx->error : -1;
        }

        /*
         * If we finished reading the headers or body, we paused parsing.
         * Otherwise the parser will start filling the body, or even parse
         * a new response if the server pipelined us multiple responses.
         * (This can happen in response to an expect/continue request,
         * where the server gives you a 100 and 200 simultaneously.)
         */
        if (http_errno == HPE_PAUSED) {
                /*
                 * http-parser has a "feature" where it will not deliver the
                 * final byte when paused in a callback.  Consume that byte.
                 * https://github.com/nodejs/http-parser/issues/97
                 */
                GIT_ASSERT(client->read_buf.size > parsed_len);

                http_parser_pause(parser, 0);

                parsed_len += http_parser_execute(parser,
                        http_client_parser_settings(),
                        client->read_buf.ptr + parsed_len,
                        1);
        }

        /* Most failures will be reported in http_errno */
        else if (parser->http_errno != HPE_OK) {
                git_error_set(GIT_ERROR_HTTP, "http parser error: %s",
                              http_errno_description(http_errno));
                return -1;
        }

        /* Otherwise we should have consumed the entire buffer. */
        else if (parsed_len != client->read_buf.size) {
                git_error_set(GIT_ERROR_HTTP,
                              "http parser did not consume entire buffer: %s",
                              http_errno_description(http_errno));
                return -1;
        }

        /* recv returned 0, the server hung up on us */
        else if (!parsed_len) {
                git_error_set(GIT_ERROR_HTTP, "unexpected EOF");
                return -1;
        }

        git_str_consume_bytes(&client->read_buf, parsed_len);

        return (int)parsed_len;
}

/*
 * See if we've consumed the entire response body.  If the client was
 * reading the body but did not consume it entirely, it's possible that
 * they knew that the stream had finished (in a git response, seeing a
 * final flush) and stopped reading.  But if the response was chunked,
 * we may have not consumed the final chunk marker.  Consume it to
 * ensure that we don't have it waiting in our socket.  If there's
 * more than just a chunk marker, close the connection.
 */
static void complete_response_body(git_http_client *client)
{
        http_parser_context parser_context = {0};

        /* If we're not keeping alive, don't bother. */
        if (!client->keepalive) {
                client->connected = 0;
                goto done;
        }

        parser_context.client = client;
        client->parser.data = &parser_context;

        /* If there was an error, just close the connection. */
        if (client_read_and_parse(client) < 0 ||
            parser_context.error != HPE_OK ||
            (parser_context.parse_status != PARSE_STATUS_OK &&
             parser_context.parse_status != PARSE_STATUS_NO_OUTPUT)) {
                git_error_clear();
                client->connected = 0;
        }

done:
        git_str_clear(&client->read_buf);
}

int git_http_client_send_request(
        git_http_client *client,
        git_http_request *request)
{
        git_http_response response = {0};
        int error = -1;

        GIT_ASSERT_ARG(client);
        GIT_ASSERT_ARG(request);

        /* If the client did not finish reading, clean up the stream. */
        if (client->state == READING_BODY)
                complete_response_body(client);

        /* If we're waiting for proxy auth, don't sending more requests. */
        if (client->state == HAS_EARLY_RESPONSE)
                return 0;

        if (git_trace_level() >= GIT_TRACE_DEBUG) {
                git_str url = GIT_STR_INIT;
                git_net_url_fmt(&url, request->url);
                git_trace(GIT_TRACE_DEBUG, "Sending %s request to %s",
                          name_for_method(request->method),
                          url.ptr ? url.ptr : "<invalid>");
                git_str_dispose(&url);
        }

        if ((error = http_client_connect(client, request)) < 0 ||
            (error = generate_request(client, request)) < 0 ||
            (error = client_write_request(client)) < 0)
                goto done;

        client->state = SENT_REQUEST;

        if (request->expect_continue) {
                if ((error = git_http_client_read_response(&response, client)) < 0 ||
                    (error = git_http_client_skip_body(client)) < 0)
                        goto done;

                error = 0;

                if (response.status != GIT_HTTP_STATUS_CONTINUE) {
                        save_early_response(client, &response);
                        goto done;
                }
        }

        if (request->content_length || request->chunked) {
                client->state = SENDING_BODY;
                client->request_body_len = request->content_length;
                client->request_body_remain = request->content_length;
                client->request_chunked = request->chunked;
        }

        reset_parser(client);

done:
        if (error == GIT_RETRY)
                error = 0;

        git_http_response_dispose(&response);
        return error;
}

bool git_http_client_has_response(git_http_client *client)
{
        return (client->state == HAS_EARLY_RESPONSE ||
                client->state > SENT_REQUEST);
}

int git_http_client_send_body(
        git_http_client *client,
        const char *buffer,
        size_t buffer_len)
{
        git_http_server *server;
        git_str hdr = GIT_STR_INIT;
        int error;

        GIT_ASSERT_ARG(client);

        /* If we're waiting for proxy auth, don't sending more requests. */
        if (client->state == HAS_EARLY_RESPONSE)
                return 0;

        if (client->state != SENDING_BODY) {
                git_error_set(GIT_ERROR_HTTP, "client is in invalid state");
                return -1;
        }

        if (!buffer_len)
                return 0;

        server = &client->server;

        if (client->request_body_len) {
                GIT_ASSERT(buffer_len <= client->request_body_remain);

                if ((error = stream_write(server, buffer, buffer_len)) < 0)
                        goto done;

                client->request_body_remain -= buffer_len;
        } else {
                if ((error = git_str_printf(&hdr, "%" PRIxZ "\r\n", buffer_len)) < 0 ||
                    (error = stream_write(server, hdr.ptr, hdr.size)) < 0 ||
                    (error = stream_write(server, buffer, buffer_len)) < 0 ||
                    (error = stream_write(server, "\r\n", 2)) < 0)
                        goto done;
        }

done:
        git_str_dispose(&hdr);
        return error;
}

static int complete_request(git_http_client *client)
{
        int error = 0;

        GIT_ASSERT_ARG(client);
        GIT_ASSERT(client->state == SENDING_BODY);

        if (client->request_body_len && client->request_body_remain) {
                git_error_set(GIT_ERROR_HTTP, "truncated write");
                error = -1;
        } else if (client->request_chunked) {
                error = stream_write(&client->server, "0\r\n\r\n", 5);
        }

        client->state = SENT_REQUEST;
        return error;
}

int git_http_client_read_response(
        git_http_response *response,
        git_http_client *client)
{
        http_parser_context parser_context = {0};
        int error;

        GIT_ASSERT_ARG(response);
        GIT_ASSERT_ARG(client);

        if (client->state == SENDING_BODY) {
                if ((error = complete_request(client)) < 0)
                        goto done;
        }

        if (client->state == HAS_EARLY_RESPONSE) {
                memcpy(response, &client->early_response, sizeof(git_http_response));
                memset(&client->early_response, 0, sizeof(git_http_response));
                client->state = DONE;
                return 0;
        }

        if (client->state != SENT_REQUEST) {
                git_error_set(GIT_ERROR_HTTP, "client is in invalid state");
                error = -1;
                goto done;
        }

        git_http_response_dispose(response);

        if (client->current_server == PROXY) {
                git_vector_free_deep(&client->proxy.auth_challenges);
        } else if(client->current_server == SERVER) {
                git_vector_free_deep(&client->server.auth_challenges);
        }

        client->state = READING_RESPONSE;
        client->keepalive = 0;
        client->parser.data = &parser_context;

        parser_context.client = client;
        parser_context.response = response;

        while (client->state == READING_RESPONSE) {
                if ((error = client_read_and_parse(client)) < 0)
                        goto done;
        }

        GIT_ASSERT(client->state == READING_BODY || client->state == DONE);

done:
        git_str_dispose(&parser_context.parse_header_name);
        git_str_dispose(&parser_context.parse_header_value);

        return error;
}

int git_http_client_read_body(
        git_http_client *client,
        char *buffer,
        size_t buffer_size)
{
        http_parser_context parser_context = {0};
        int error = 0;

        if (client->state == DONE)
                return 0;

        if (client->state != READING_BODY) {
                git_error_set(GIT_ERROR_HTTP, "client is in invalid state");
                return -1;
        }

        /*
         * Now we'll read from the socket and http_parser will pipeline the
         * data directly to the client.
         */

        parser_context.client = client;
        parser_context.output_buf = buffer;
        parser_context.output_size = buffer_size;

        client->parser.data = &parser_context;

        /*
         * Clients expect to get a non-zero amount of data from us,
         * so we either block until we have data to return, until we
         * hit EOF or there's an error.  Do this in a loop, since we
         * may end up reading only some stream metadata (like chunk
         * information).
         */
        while (!parser_context.output_written) {
                error = client_read_and_parse(client);

                if (error <= 0)
                        goto done;

                if (client->state == DONE)
                        break;
        }

        GIT_ASSERT(parser_context.output_written <= INT_MAX);
        error = (int)parser_context.output_written;

done:
        if (error < 0)
                client->connected = 0;

        return error;
}

int git_http_client_skip_body(git_http_client *client)
{
        http_parser_context parser_context = {0};
        int error;

        if (client->state == DONE)
                return 0;

        if (client->state != READING_BODY) {
                git_error_set(GIT_ERROR_HTTP, "client is in invalid state");
                return -1;
        }

        parser_context.client = client;
        client->parser.data = &parser_context;

        do {
                error = client_read_and_parse(client);

                if (parser_context.error != HPE_OK ||
                    (parser_context.parse_status != PARSE_STATUS_OK &&
                     parser_context.parse_status != PARSE_STATUS_NO_OUTPUT)) {
                        git_error_set(GIT_ERROR_HTTP,
                                      "unexpected data handled in callback");
                        error = -1;
                }
        } while (error >= 0 && client->state != DONE);

        if (error < 0)
                client->connected = 0;

        return error;
}

/*
 * Create an http_client capable of communicating with the given remote
 * host.
 */
int git_http_client_new(
        git_http_client **out,
        git_http_client_options *opts)
{
        git_http_client *client;

        GIT_ASSERT_ARG(out);

        client = git__calloc(1, sizeof(git_http_client));
        GIT_ERROR_CHECK_ALLOC(client);

        git_str_init(&client->read_buf, GIT_READ_BUFFER_SIZE);
        GIT_ERROR_CHECK_ALLOC(client->read_buf.ptr);

        if (opts)
                memcpy(&client->opts, opts, sizeof(git_http_client_options));

        *out = client;
        return 0;
}

GIT_INLINE(void) http_server_close(git_http_server *server)
{
        if (server->stream) {
                git_stream_close(server->stream);
                git_stream_free(server->stream);
                server->stream = NULL;
        }

        git_net_url_dispose(&server->url);

        git_vector_free_deep(&server->auth_challenges);
        free_auth_context(server);
}

static void http_client_close(git_http_client *client)
{
        http_server_close(&client->server);
        http_server_close(&client->proxy);

        git_str_dispose(&client->request_msg);

        client->state = 0;
        client->request_count = 0;
        client->connected = 0;
        client->keepalive = 0;
}

void git_http_client_free(git_http_client *client)
{
        if (!client)
                return;

        http_client_close(client);
        git_str_dispose(&client->read_buf);
        git__free(client);
}