threaded-ssl.c
/*************************************************************************** * _ _ ____ _ * Project ___| | | | _ \| | * / __| | | | |_) | | * | (__| |_| | _ <| |___ * \___|\___/|_| \_\_____| * * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. * * This software is licensed as described in the file COPYING, which * you should have received as part of this distribution. The terms * are also available at https://curl.se/docs/copyright.html. * * You may opt to use, copy, modify, merge, publish, distribute and/or sell * copies of the Software, and permit persons to whom the Software is * furnished to do so, under the terms of the COPYING file. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * * SPDX-License-Identifier: curl * ***************************************************************************/ /* <DESC> * Show the required mutex callback setups for GnuTLS and OpenSSL when using * libcurl multi-threaded. * </DESC> */ /* A multi-threaded example that uses pthreads and fetches 4 remote files at * once over HTTPS. * * Recent versions of OpenSSL and GnuTLS are thread safe by design, assuming * support for the underlying OS threading API is built-in. Older revisions * of this example demonstrated locking callbacks for the SSL library, which * are no longer necessary. An older revision with callbacks can be found at * https://github.com/curl/curl/blob/curl-7_88_1/docs/examples/threaded-ssl.c */ #define USE_OPENSSL /* or USE_GNUTLS accordingly */ #include <stdio.h> #include <pthread.h> #include <curl/curl.h> #define NUMT 4 /* List of URLs to fetch.*/ static const char * const urls[]= { "https://www.example.com/", "https://www2.example.com/", "https://www3.example.com/", "https://www4.example.com/", }; static void *pull_one_url(void *url) { CURL *curl; curl = curl_easy_init(); curl_easy_setopt(curl, CURLOPT_URL, url); /* this example does not verify the server's certificate, which means we might be downloading stuff from an impostor */ curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L); curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L); curl_easy_perform(curl); /* ignores error */ curl_easy_cleanup(curl); return NULL; } int main(int argc, char **argv) { pthread_t tid[NUMT]; int i; (void)argc; /* we do not use any arguments in this example */ (void)argv; /* Must initialize libcurl before any threads are started */ curl_global_init(CURL_GLOBAL_ALL); for(i = 0; i < NUMT; i++) { int error = pthread_create(&tid[i], NULL, /* default attributes please */ pull_one_url, (void *)urls[i]); if(0 != error) fprintf(stderr, "Couldn't run thread number %d, errno %d\n", i, error); else fprintf(stderr, "Thread %d, gets %s\n", i, urls[i]); } /* now wait for all threads to terminate */ for(i = 0; i < NUMT; i++) { pthread_join(tid[i], NULL); fprintf(stderr, "Thread %d terminated\n", i); } return 0; }
Notice
This source code example is simplified and ignores return
codes and error checks to a large extent. We do this to highlight the libcurl
function calls and related options and reduce unrelated code.
A real-world application will of course properly check every return value and exit correctly at the first serious error.