libasteriskssl.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2009-2012, Digium, Inc.
 *
 * Russell Bryant <russell@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*!
 * \file
 * \brief Common OpenSSL support code
 *
 * \author Russell Bryant <russell@digium.com>
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 353317 $")

#ifdef HAVE_OPENSSL
#include <openssl/ssl.h>
#include <openssl/err.h>
#endif

#include <dlfcn.h>

#include "asterisk/_private.h" /* ast_ssl_init() */

#include "asterisk/utils.h"
#include "asterisk/lock.h"

#ifdef HAVE_OPENSSL

#define get_OpenSSL_function(func) do { real_##func = dlsym(RTLD_NEXT, __stringify(func)); } while(0)

static int startup_complete;

static ast_mutex_t *ssl_locks;

static int ssl_num_locks;

static unsigned long ssl_threadid(void)
{
   return (unsigned long) pthread_self();
}

static void ssl_lock(int mode, int n, const char *file, int line)
{
   if (n < 0 || n >= ssl_num_locks) {
      ast_log(LOG_ERROR, "OpenSSL is full of LIES!!! - "
            "ssl_num_locks '%d' - n '%d'\n",
            ssl_num_locks, n);
      return;
   }

   if (mode & CRYPTO_LOCK) {
      ast_mutex_lock(&ssl_locks[n]);
   } else {
      ast_mutex_unlock(&ssl_locks[n]);
   }
}

int SSL_library_init(void)
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
   return 0;
}

void SSL_load_error_strings(void)
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
}

void ERR_load_SSL_strings(void)
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
}

void ERR_load_crypto_strings(void)
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
}

void ERR_load_BIO_strings(void)
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
}

void CRYPTO_set_id_callback(unsigned long (*func)(void))
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
}

void CRYPTO_set_locking_callback(void (*func)(int mode,int type, const char *file, int line))
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
}

void ERR_free_strings(void)
{
   /* we can't allow this to be called, ever */
}

#endif /* HAVE_OPENSSL */

/*!
 * \internal
 * \brief Common OpenSSL initialization for all of Asterisk.
 */
int ast_ssl_init(void)
{
#ifdef HAVE_OPENSSL
   unsigned int i;
   int (*real_SSL_library_init)(void);
   void (*real_CRYPTO_set_id_callback)(unsigned long (*)(void));
   void (*real_CRYPTO_set_locking_callback)(void (*)(int, int, const char *, int));
   void (*real_SSL_load_error_strings)(void);
   void (*real_ERR_load_SSL_strings)(void);
   void (*real_ERR_load_crypto_strings)(void);
   void (*real_ERR_load_BIO_strings)(void);
   const char *errstr;

   /* clear any previous dynamic linker errors */
   dlerror();
   get_OpenSSL_function(SSL_library_init);
   if ((errstr = dlerror()) != NULL) {
      ast_debug(1, "unable to get real address of SSL_library_init: %s\n", errstr);
      /* there is no way to continue in this situation... SSL will
       * likely be broken in this process
       */
      return -1;
   } else {
      real_SSL_library_init();
   }

   /* Make OpenSSL usage thread-safe. */

   dlerror();
   get_OpenSSL_function(CRYPTO_set_id_callback);
   if ((errstr = dlerror()) != NULL) {
      ast_debug(1, "unable to get real address of CRYPTO_set_id_callback: %s\n", errstr);
      /* there is no way to continue in this situation... SSL will
       * likely be broken in this process
       */
      return -1;
   } else {
      real_CRYPTO_set_id_callback(ssl_threadid);
   }

   dlerror();
   get_OpenSSL_function(CRYPTO_set_locking_callback);
   if ((errstr = dlerror()) != NULL) {
      ast_debug(1, "unable to get real address of CRYPTO_set_locking_callback: %s\n", errstr);
      /* there is no way to continue in this situation... SSL will
       * likely be broken in this process
       */
      return -1;
   } else {
      ssl_num_locks = CRYPTO_num_locks();
      if (!(ssl_locks = ast_calloc(ssl_num_locks, sizeof(ssl_locks[0])))) {
         return -1;
      }
      for (i = 0; i < ssl_num_locks; i++) {
         ast_mutex_init(&ssl_locks[i]);
      }
      real_CRYPTO_set_locking_callback(ssl_lock);
   }

   /* after this point, we don't check for errors from the dlsym() calls,
    * under the assumption that if the ones above were successful, all
    * the rest will be too. this assumption holds as long as OpenSSL still
    * provides all of these functions.
    */

   get_OpenSSL_function(SSL_load_error_strings);
   real_SSL_load_error_strings();

   get_OpenSSL_function(ERR_load_SSL_strings);
   real_ERR_load_SSL_strings();

   get_OpenSSL_function(ERR_load_crypto_strings);
   real_ERR_load_crypto_strings();

   get_OpenSSL_function(ERR_load_BIO_strings);
   real_ERR_load_BIO_strings();

#if 0
   /* currently this is just another call to SSL_library_init, so we don't call it */
   OpenSSL_add_all_algorithms();
#endif

   startup_complete = 1;

#endif /* HAVE_OPENSSL */
   return 0;
}