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      1 /***************************************************************************
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      6  *                             \___|\___/|_| \_\_____|
      7  *
      8  * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel (at) haxx.se>, et al.
      9  *
     10  * This software is licensed as described in the file COPYING, which
     11  * you should have received as part of this distribution. The terms
     12  * are also available at https://curl.haxx.se/docs/copyright.html.
     13  *
     14  * You may opt to use, copy, modify, merge, publish, distribute and/or sell
     15  * copies of the Software, and permit persons to whom the Software is
     16  * furnished to do so, under the terms of the COPYING file.
     17  *
     18  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
     19  * KIND, either express or implied.
     20  *
     21  ***************************************************************************/
     22 /* <DESC>
     23  * Show the required mutex callback setups for GnuTLS and OpenSSL when using
     24  * libcurl multi-threaded.
     25  * </DESC>
     26  */
     27 /* A multi-threaded example that uses pthreads and fetches 4 remote files at
     28  * once over HTTPS. The lock callbacks and stuff assume OpenSSL <1.1 or GnuTLS
     29  * (libgcrypt) so far.
     30  *
     31  * OpenSSL docs for this:
     32  *   https://www.openssl.org/docs/crypto/threads.html
     33  * gcrypt docs for this:
     34  *   https://gnupg.org/documentation/manuals/gcrypt/Multi_002dThreading.html
     35  */
     36 
     37 #define USE_OPENSSL /* or USE_GNUTLS accordingly */
     38 
     39 #include <stdio.h>
     40 #include <pthread.h>
     41 #include <curl/curl.h>
     42 
     43 #define NUMT 4
     44 
     45 /* we have this global to let the callback get easy access to it */
     46 static pthread_mutex_t *lockarray;
     47 
     48 #ifdef USE_OPENSSL
     49 #include <openssl/crypto.h>
     50 static void lock_callback(int mode, int type, char *file, int line)
     51 {
     52   (void)file;
     53   (void)line;
     54   if(mode & CRYPTO_LOCK) {
     55     pthread_mutex_lock(&(lockarray[type]));
     56   }
     57   else {
     58     pthread_mutex_unlock(&(lockarray[type]));
     59   }
     60 }
     61 
     62 static unsigned long thread_id(void)
     63 {
     64   unsigned long ret;
     65 
     66   ret = (unsigned long)pthread_self();
     67   return ret;
     68 }
     69 
     70 static void init_locks(void)
     71 {
     72   int i;
     73 
     74   lockarray = (pthread_mutex_t *)OPENSSL_malloc(CRYPTO_num_locks() *
     75                                                 sizeof(pthread_mutex_t));
     76   for(i = 0; i<CRYPTO_num_locks(); i++) {
     77     pthread_mutex_init(&(lockarray[i]), NULL);
     78   }
     79 
     80   CRYPTO_set_id_callback((unsigned long (*)())thread_id);
     81   CRYPTO_set_locking_callback((void (*)())lock_callback);
     82 }
     83 
     84 static void kill_locks(void)
     85 {
     86   int i;
     87 
     88   CRYPTO_set_locking_callback(NULL);
     89   for(i = 0; i<CRYPTO_num_locks(); i++)
     90     pthread_mutex_destroy(&(lockarray[i]));
     91 
     92   OPENSSL_free(lockarray);
     93 }
     94 #endif
     95 
     96 #ifdef USE_GNUTLS
     97 #include <gcrypt.h>
     98 #include <errno.h>
     99 
    100 GCRY_THREAD_OPTION_PTHREAD_IMPL;
    101 
    102 void init_locks(void)
    103 {
    104   gcry_control(GCRYCTL_SET_THREAD_CBS);
    105 }
    106 
    107 #define kill_locks()
    108 #endif
    109 
    110 /* List of URLs to fetch.*/
    111 const char * const urls[]= {
    112   "https://www.example.com/",
    113   "https://www2.example.com/",
    114   "https://www3.example.com/",
    115   "https://www4.example.com/",
    116 };
    117 
    118 static void *pull_one_url(void *url)
    119 {
    120   CURL *curl;
    121 
    122   curl = curl_easy_init();
    123   curl_easy_setopt(curl, CURLOPT_URL, url);
    124   /* this example doesn't verify the server's certificate, which means we
    125      might be downloading stuff from an impostor */
    126   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
    127   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
    128   curl_easy_perform(curl); /* ignores error */
    129   curl_easy_cleanup(curl);
    130 
    131   return NULL;
    132 }
    133 
    134 int main(int argc, char **argv)
    135 {
    136   pthread_t tid[NUMT];
    137   int i;
    138   int error;
    139   (void)argc; /* we don't use any arguments in this example */
    140   (void)argv;
    141 
    142   /* Must initialize libcurl before any threads are started */
    143   curl_global_init(CURL_GLOBAL_ALL);
    144 
    145   init_locks();
    146 
    147   for(i = 0; i< NUMT; i++) {
    148     error = pthread_create(&tid[i],
    149                            NULL, /* default attributes please */
    150                            pull_one_url,
    151                            (void *)urls[i]);
    152     if(0 != error)
    153       fprintf(stderr, "Couldn't run thread number %d, errno %d\n", i, error);
    154     else
    155       fprintf(stderr, "Thread %d, gets %s\n", i, urls[i]);
    156   }
    157 
    158   /* now wait for all threads to terminate */
    159   for(i = 0; i< NUMT; i++) {
    160     error = pthread_join(tid[i], NULL);
    161     fprintf(stderr, "Thread %d terminated\n", i);
    162   }
    163 
    164   kill_locks();
    165 
    166   return 0;
    167 }
    168