Cryptlib/OpenSSL/crypto/cryptlib.c

   1 /* crypto/cryptlib.c */
   2 /* ====================================================================
   3  * Copyright (c) 1998-2003 The OpenSSL Project.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  *
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in
  14  *    the documentation and/or other materials provided with the
  15  *    distribution.
  16  *
  17  * 3. All advertising materials mentioning features or use of this
  18  *    software must display the following acknowledgment:
  19  *    "This product includes software developed by the OpenSSL Project
  20  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  21  *
  22  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  23  *    endorse or promote products derived from this software without
  24  *    prior written permission. For written permission, please contact
  25  *    openssl-core@openssl.org.
  26  *
  27  * 5. Products derived from this software may not be called "OpenSSL"
  28  *    nor may "OpenSSL" appear in their names without prior written
  29  *    permission of the OpenSSL Project.
  30  *
  31  * 6. Redistributions of any form whatsoever must retain the following
  32  *    acknowledgment:
  33  *    "This product includes software developed by the OpenSSL Project
  34  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  35  *
  36  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  37  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  38  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  39  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  40  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  41  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  42  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  43  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  44  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  45  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  46  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  47  * OF THE POSSIBILITY OF SUCH DAMAGE.
  48  * ====================================================================
  49  *
  50  * This product includes cryptographic software written by Eric Young
  51  * (eay@cryptsoft.com).  This product includes software written by Tim
  52  * Hudson (tjh@cryptsoft.com).
  53  *
  54  */
  55 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  56  * All rights reserved.
  57  *
  58  * This package is an SSL implementation written
  59  * by Eric Young (eay@cryptsoft.com).
  60  * The implementation was written so as to conform with Netscapes SSL.
  61  *
  62  * This library is free for commercial and non-commercial use as long as
  63  * the following conditions are aheared to.  The following conditions
  64  * apply to all code found in this distribution, be it the RC4, RSA,
  65  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  66  * included with this distribution is covered by the same copyright terms
  67  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  68  *
  69  * Copyright remains Eric Young's, and as such any Copyright notices in
  70  * the code are not to be removed.
  71  * If this package is used in a product, Eric Young should be given attribution
  72  * as the author of the parts of the library used.
  73  * This can be in the form of a textual message at program startup or
  74  * in documentation (online or textual) provided with the package.
  75  *
  76  * Redistribution and use in source and binary forms, with or without
  77  * modification, are permitted provided that the following conditions
  78  * are met:
  79  * 1. Redistributions of source code must retain the copyright
  80  *    notice, this list of conditions and the following disclaimer.
  81  * 2. Redistributions in binary form must reproduce the above copyright
  82  *    notice, this list of conditions and the following disclaimer in the
  83  *    documentation and/or other materials provided with the distribution.
  84  * 3. All advertising materials mentioning features or use of this software
  85  *    must display the following acknowledgement:
  86  *    "This product includes cryptographic software written by
  87  *     Eric Young (eay@cryptsoft.com)"
  88  *    The word 'cryptographic' can be left out if the rouines from the library
  89  *    being used are not cryptographic related :-).
  90  * 4. If you include any Windows specific code (or a derivative thereof) from
  91  *    the apps directory (application code) you must include an acknowledgement:
  92  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  93  *
  94  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  95  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  96  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  97  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  98  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  99  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 100  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 101  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 102  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 103  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 104  * SUCH DAMAGE.
 105  *
 106  * The licence and distribution terms for any publically available version or
 107  * derivative of this code cannot be changed.  i.e. this code cannot simply be
 108  * copied and put under another distribution licence
 109  * [including the GNU Public Licence.]
 110  */
 111 /* ====================================================================
 112  * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
 113  * ECDH support in OpenSSL originally developed by
 114  * SUN MICROSYSTEMS, INC., and contributed to the OpenSSL project.
 115  */
 116
 117 #include "cryptlib.h"
 118 #include <openssl/safestack.h>
 119
 120 #if defined(OPENSSL_SYS_WIN32) || defined(OPENSSL_SYS_WIN16)
 121 static double SSLeay_MSVC5_hack = 0.0; /* and for VC1.5 */
 122 #endif
 123
 124 static void (MS_FAR *locking_callback) (int mode, int type,
 125                                         const char *file, int line) = NULL;
 126 static int (MS_FAR *add_lock_callback) (int *pointer, int amount,
 127                                         int type, const char *file,
 128                                         int line) = NULL;
 129 static unsigned long (MS_FAR *id_callback) (void) = NULL;
 130
 131 int CRYPTO_num_locks(void)
 132 {
 133     return CRYPTO_NUM_LOCKS;
 134 }
 135
 136 void (*CRYPTO_get_locking_callback(void)) (int mode, int type,
 137                                            const char *file, int line) {
 138     return (locking_callback);
 139 }
 140
 141 int (*CRYPTO_get_add_lock_callback(void)) (int *num, int mount, int type,
 142                                            const char *file, int line) {
 143     return (add_lock_callback);
 144 }
 145
 146 void CRYPTO_set_locking_callback(void (*func) (int mode, int type,
 147                                                const char *file, int line))
 148 {
 149     locking_callback = func;
 150 }
 151
 152 void CRYPTO_set_add_lock_callback(int (*func) (int *num, int mount, int type,
 153                                                const char *file, int line))
 154 {
 155     add_lock_callback = func;
 156 }
 157
 158 unsigned long (*CRYPTO_get_id_callback(void)) (void) {
 159     return (id_callback);
 160 }
 161
 162 void CRYPTO_set_id_callback(unsigned long (*func) (void))
 163 {
 164     id_callback = func;
 165 }
 166
 167 unsigned long CRYPTO_thread_id(void)
 168 {
 169     unsigned long ret = 0;
 170
 171     if (id_callback == NULL) {
 172 #ifdef OPENSSL_SYS_WIN16
 173         ret = (unsigned long)GetCurrentTask();
 174 #elif defined(OPENSSL_SYS_WIN32)
 175         ret = (unsigned long)GetCurrentThreadId();
 176 #elif defined(GETPID_IS_MEANINGLESS)
 177         ret = 1L;
 178 #else
 179         ret = (unsigned long)getpid();
 180 #endif
 181     } else
 182         ret = id_callback();
 183     return (ret);
 184 }
 185
 186 static void (*do_dynlock_cb) (int mode, int type, const char *file, int line);
 187
 188 void int_CRYPTO_set_do_dynlock_callback(void (*dyn_cb)
 189                                          (int mode, int type,
 190                                           const char *file, int line))
 191 {
 192     do_dynlock_cb = dyn_cb;
 193 }
 194
 195 void CRYPTO_lock(int mode, int type, const char *file, int line)
 196 {
 197 #ifdef LOCK_DEBUG
 198     {
 199         char *rw_text, *operation_text;
 200
 201         if (mode & CRYPTO_LOCK)
 202             operation_text = "lock  ";
 203         else if (mode & CRYPTO_UNLOCK)
 204             operation_text = "unlock";
 205         else
 206             operation_text = "ERROR ";
 207
 208         if (mode & CRYPTO_READ)
 209             rw_text = "r";
 210         else if (mode & CRYPTO_WRITE)
 211             rw_text = "w";
 212         else
 213             rw_text = "ERROR";
 214
 215         fprintf(stderr, "lock:%08lx:(%s)%s %-18s %s:%d\n",
 216                 CRYPTO_thread_id(), rw_text, operation_text,
 217                 CRYPTO_get_lock_name(type), file, line);
 218     }
 219 #endif
 220     if (type < 0) {
 221         if (do_dynlock_cb)
 222             do_dynlock_cb(mode, type, file, line);
 223     } else if (locking_callback != NULL)
 224         locking_callback(mode, type, file, line);
 225 }
 226
 227 int CRYPTO_add_lock(int *pointer, int amount, int type, const char *file,
 228                     int line)
 229 {
 230     int ret = 0;
 231
 232     if (add_lock_callback != NULL) {
 233 #ifdef LOCK_DEBUG
 234         int before = *pointer;
 235 #endif
 236
 237         ret = add_lock_callback(pointer, amount, type, file, line);
 238 #ifdef LOCK_DEBUG
 239         fprintf(stderr, "ladd:%08lx:%2d+%2d->%2d %-18s %s:%d\n",
 240                 CRYPTO_thread_id(),
 241                 before, amount, ret, CRYPTO_get_lock_name(type), file, line);
 242 #endif
 243     } else {
 244         CRYPTO_lock(CRYPTO_LOCK | CRYPTO_WRITE, type, file, line);
 245
 246         ret = *pointer + amount;
 247 #ifdef LOCK_DEBUG
 248         fprintf(stderr, "ladd:%08lx:%2d+%2d->%2d %-18s %s:%d\n",
 249                 CRYPTO_thread_id(),
 250                 *pointer, amount, ret,
 251                 CRYPTO_get_lock_name(type), file, line);
 252 #endif
 253         *pointer = ret;
 254         CRYPTO_lock(CRYPTO_UNLOCK | CRYPTO_WRITE, type, file, line);
 255     }
 256     return (ret);
 257 }
 258
 259 #if     defined(__i386)   || defined(__i386__)   || defined(_M_IX86) || \
 260         defined(__INTEL__) || \
 261         defined(__x86_64) || defined(__x86_64__) || \
 262         defined(_M_AMD64) || defined(_M_X64)
 263
 264 unsigned long OPENSSL_ia32cap_P = 0;
 265 unsigned long *OPENSSL_ia32cap_loc(void)
 266 {
 267     return &OPENSSL_ia32cap_P;
 268 }
 269
 270 # if defined(OPENSSL_CPUID_OBJ) && !defined(OPENSSL_NO_ASM) && !defined(I386_ONLY)
 271 #  define OPENSSL_CPUID_SETUP
 272 void OPENSSL_cpuid_setup(void)
 273 {
 274     static int trigger = 0;
 275     unsigned long OPENSSL_ia32_cpuid(void);
 276     char *env;
 277
 278     if (trigger)
 279         return;
 280
 281     trigger = 1;
 282     if ((env = getenv("OPENSSL_ia32cap")))
 283         OPENSSL_ia32cap_P = strtoul(env, NULL, 0) | (1 << 10);
 284     else
 285         OPENSSL_ia32cap_P = OPENSSL_ia32_cpuid() | (1 << 10);
 286     /*
 287      * |(1<<10) sets a reserved bit to signal that variable
 288      * was initialized already... This is to avoid interference
 289      * with cpuid snippets in ELF .init segment.
 290      */
 291 }
 292 # endif
 293
 294 #else
 295 unsigned long *OPENSSL_ia32cap_loc(void)
 296 {
 297     return NULL;
 298 }
 299 #endif
 300 int OPENSSL_NONPIC_relocated = 0;
 301 #if !defined(OPENSSL_CPUID_SETUP)
 302 void OPENSSL_cpuid_setup(void)
 303 {
 304 }
 305 #endif
 306
 307 #if (defined(_WIN32) || defined(__CYGWIN__)) && defined(_WINDLL)
 308
 309 # ifdef OPENSSL_FIPS
 310
 311 #  include <tlhelp32.h>
 312 #  if defined(__GNUC__) && __GNUC__>=2
 313 static int DllInit(void) __attribute__ ((constructor));
 314 #  elif defined(_MSC_VER)
 315 static int DllInit(void);
 316 #   ifdef _WIN64
 317 #    pragma section(".CRT$XCU",read)
 318 __declspec(allocate(".CRT$XCU"))
 319 #   else
 320 #    pragma data_seg(".CRT$XCU")
 321 #   endif
 322 static int (*p) (void) = DllInit;
 323 #   pragma data_seg()
 324 #  endif
 325
 326 static int DllInit(void)
 327 {
 328 #  if defined(_WIN32_WINNT)
 329     union {
 330         int (*f) (void);
 331         BYTE *p;
 332     } t = {
 333         DllInit
 334     };
 335     HANDLE hModuleSnap = INVALID_HANDLE_VALUE;
 336     IMAGE_DOS_HEADER *dos_header;
 337     IMAGE_NT_HEADERS *nt_headers;
 338     MODULEENTRY32 me32 = { sizeof(me32) };
 339
 340     hModuleSnap = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, 0);
 341     if (hModuleSnap != INVALID_HANDLE_VALUE &&
 342         Module32First(hModuleSnap, &me32))
 343         do {
 344             if (t.p >= me32.modBaseAddr &&
 345                 t.p < me32.modBaseAddr + me32.modBaseSize) {
 346                 dos_header = (IMAGE_DOS_HEADER *) me32.modBaseAddr;
 347                 if (dos_header->e_magic == IMAGE_DOS_SIGNATURE) {
 348                     nt_headers = (IMAGE_NT_HEADERS *)
 349                         ((BYTE *) dos_header + dos_header->e_lfanew);
 350                     if (nt_headers->Signature == IMAGE_NT_SIGNATURE &&
 351                         me32.modBaseAddr !=
 352                         (BYTE *) nt_headers->OptionalHeader.ImageBase)
 353                         OPENSSL_NONPIC_relocated = 1;
 354                 }
 355                 break;
 356             }
 357         } while (Module32Next(hModuleSnap, &me32));
 358
 359     if (hModuleSnap != INVALID_HANDLE_VALUE)
 360         CloseHandle(hModuleSnap);
 361 #  endif
 362     OPENSSL_cpuid_setup();
 363     return 0;
 364 }
 365
 366 # else
 367
 368 #  ifdef __CYGWIN__
 369 /* pick DLL_[PROCESS|THREAD]_[ATTACH|DETACH] definitions */
 370 #   include <windows.h>
 371 #  endif
 372
 373 /*
 374  * All we really need to do is remove the 'error' state when a thread
 375  * detaches
 376  */
 377
 378 BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
 379 {
 380     switch (fdwReason) {
 381     case DLL_PROCESS_ATTACH:
 382         OPENSSL_cpuid_setup();
 383 #  if defined(_WIN32_WINNT)
 384         {
 385             IMAGE_DOS_HEADER *dos_header = (IMAGE_DOS_HEADER *) hinstDLL;
 386             IMAGE_NT_HEADERS *nt_headers;
 387
 388             if (dos_header->e_magic == IMAGE_DOS_SIGNATURE) {
 389                 nt_headers = (IMAGE_NT_HEADERS *) ((char *)dos_header
 390                                                    + dos_header->e_lfanew);
 391                 if (nt_headers->Signature == IMAGE_NT_SIGNATURE &&
 392                     hinstDLL !=
 393                     (HINSTANCE) (nt_headers->OptionalHeader.ImageBase))
 394                     OPENSSL_NONPIC_relocated = 1;
 395             }
 396         }
 397 #  endif
 398         break;
 399     case DLL_THREAD_ATTACH:
 400         break;
 401     case DLL_THREAD_DETACH:
 402         break;
 403     case DLL_PROCESS_DETACH:
 404         break;
 405     }
 406     return (TRUE);
 407 }
 408 # endif
 409
 410 #endif
 411
 412 #if defined(_WIN32) && !defined(__CYGWIN__)
 413 # include <tchar.h>
 414
 415 # if defined(_WIN32_WINNT) && _WIN32_WINNT>=0x0333
 416 int OPENSSL_isservice(void)
 417 {
 418     HWINSTA h;
 419     DWORD len;
 420     WCHAR *name;
 421
 422     (void)GetDesktopWindow();   /* return value is ignored */
 423
 424     h = GetProcessWindowStation();
 425     if (h == NULL)
 426         return -1;
 427
 428     if (GetUserObjectInformationW(h, UOI_NAME, NULL, 0, &len) ||
 429         GetLastError() != ERROR_INSUFFICIENT_BUFFER)
 430         return -1;
 431
 432     if (len > 512)
 433         return -1;              /* paranoia */
 434     len++, len &= ~1;           /* paranoia */
 435 #  ifdef _MSC_VER
 436     name = (WCHAR *)_alloca(len + sizeof(WCHAR));
 437 #  else
 438     name = (WCHAR *)alloca(len + sizeof(WCHAR));
 439 #  endif
 440     if (!GetUserObjectInformationW(h, UOI_NAME, name, len, &len))
 441         return -1;
 442
 443     len++, len &= ~1;           /* paranoia */
 444     name[len / sizeof(WCHAR)] = L'\0'; /* paranoia */
 445 #  if 1
 446     /*
 447      * This doesn't cover "interactive" services [working with real
 448      * WinSta0's] nor programs started non-interactively by Task Scheduler
 449      * [those are working with SAWinSta].
 450      */
 451     if (wcsstr(name, L"Service-0x"))
 452         return 1;
 453 #  else
 454     /* This covers all non-interactive programs such as services. */
 455     if (!wcsstr(name, L"WinSta0"))
 456         return 1;
 457 #  endif
 458     else
 459         return 0;
 460 }
 461 # else
 462 int OPENSSL_isservice(void)
 463 {
 464     return 0;
 465 }
 466 # endif
 467
 468 void OPENSSL_showfatal(const char *fmta, ...)
 469 {
 470     va_list ap;
 471     TCHAR buf[256];
 472     const TCHAR *fmt;
 473 # ifdef STD_ERROR_HANDLE        /* what a dirty trick! */
 474     HANDLE h;
 475
 476     if ((h = GetStdHandle(STD_ERROR_HANDLE)) != NULL &&
 477         GetFileType(h) != FILE_TYPE_UNKNOWN) {
 478         /* must be console application */
 479         va_start(ap, fmta);
 480         vfprintf(stderr, fmta, ap);
 481         va_end(ap);
 482         return;
 483     }
 484 # endif
 485
 486     if (sizeof(TCHAR) == sizeof(char))
 487         fmt = (const TCHAR *)fmta;
 488     else
 489         do {
 490             int keepgoing;
 491             size_t len_0 = strlen(fmta) + 1, i;
 492             WCHAR *fmtw;
 493
 494 # ifdef _MSC_VER
 495             fmtw = (WCHAR *)_alloca(len_0 * sizeof(WCHAR));
 496 # else
 497             fmtw = (WCHAR *)alloca(len_0 * sizeof(WCHAR));
 498 # endif
 499             if (fmtw == NULL) {
 500                 fmt = (const TCHAR *)L"no stack?";
 501                 break;
 502             }
 503 # ifndef OPENSSL_NO_MULTIBYTE
 504             if (!MultiByteToWideChar(CP_ACP, 0, fmta, len_0, fmtw, len_0))
 505 # endif
 506                 for (i = 0; i < len_0; i++)
 507                     fmtw[i] = (WCHAR)fmta[i];
 508
 509             for (i = 0; i < len_0; i++) {
 510                 if (fmtw[i] == L'%')
 511                     do {
 512                         keepgoing = 0;
 513                         switch (fmtw[i + 1]) {
 514                         case L'0':
 515                         case L'1':
 516                         case L'2':
 517                         case L'3':
 518                         case L'4':
 519                         case L'5':
 520                         case L'6':
 521                         case L'7':
 522                         case L'8':
 523                         case L'9':
 524                         case L'.':
 525                         case L'*':
 526                         case L'-':
 527                             i++;
 528                             keepgoing = 1;
 529                             break;
 530                         case L's':
 531                             fmtw[i + 1] = L'S';
 532                             break;
 533                         case L'S':
 534                             fmtw[i + 1] = L's';
 535                             break;
 536                         case L'c':
 537                             fmtw[i + 1] = L'C';
 538                             break;
 539                         case L'C':
 540                             fmtw[i + 1] = L'c';
 541                             break;
 542                         }
 543                     } while (keepgoing);
 544             }
 545             fmt = (const TCHAR *)fmtw;
 546         } while (0);
 547
 548     va_start(ap, fmta);
 549     _vsntprintf(buf, sizeof(buf) / sizeof(TCHAR) - 1, fmt, ap);
 550     buf[sizeof(buf) / sizeof(TCHAR) - 1] = _T('\0');
 551     va_end(ap);
 552
 553 # if defined(_WIN32_WINNT) && _WIN32_WINNT>=0x0333
 554     /* this -------------v--- guards NT-specific calls */
 555     if (check_winnt() && OPENSSL_isservice() > 0) {
 556         HANDLE h = RegisterEventSource(0, _T("OPENSSL"));
 557         const TCHAR *pmsg = buf;
 558         ReportEvent(h, EVENTLOG_ERROR_TYPE, 0, 0, 0, 1, 0, &pmsg, 0);
 559         DeregisterEventSource(h);
 560     } else
 561 # endif
 562         MessageBox(NULL, buf, _T("OpenSSL: FATAL"), MB_OK | MB_ICONSTOP);
 563 }
 564 #else
 565 void OPENSSL_showfatal(const char *fmta, ...)
 566 {
 567     va_list ap;
 568
 569     va_start(ap, fmta);
 570     vfprintf(stderr, fmta, ap);
 571     va_end(ap);
 572 }
 573
 574 int OPENSSL_isservice(void)
 575 {
 576     return 0;
 577 }
 578 #endif
 579
 580 void OpenSSLDie(const char *file, int line, const char *assertion)
 581 {
 582     OPENSSL_showfatal
 583         ("%s(%d): OpenSSL internal error, assertion failed: %s\n", file, line,
 584          assertion);
 585     abort();
 586 }
 587
 588 void *OPENSSL_stderr(void)
 589 {
 590     return stderr;
 591 }
 592
 593 #ifndef OPENSSL_FIPS
 594
 595 int CRYPTO_memcmp(const void *in_a, const void *in_b, size_t len)
 596 {
 597     size_t i;
 598     const unsigned char *a = in_a;
 599     const unsigned char *b = in_b;
 600     unsigned char x = 0;
 601
 602     for (i = 0; i < len; i++)
 603         x |= a[i] ^ b[i];
 604
 605     return x;
 606 }
 607 #endif