xref: /third_party/curl/docs/examples/connect-to.c (revision 13498266)
1/***************************************************************************
2 *                                  _   _ ____  _
3 *  Project                     ___| | | |  _ \| |
4 *                             / __| | | | |_) | |
5 *                            | (__| |_| |  _ <| |___
6 *                             \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) Daniel Stenberg, <daniel@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.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 * SPDX-License-Identifier: curl
22 *
23 ***************************************************************************/
24/* <DESC>
25 * Use CURLOPT_CONNECT_TO to connect to "wrong" host name
26 * </DESC>
27 */
28#include <stdio.h>
29#include <curl/curl.h>
30
31int main(void)
32{
33  CURL *curl;
34  CURLcode res = CURLE_OK;
35
36  /*
37    Each single string should be written using the format
38    HOST:PORT:CONNECT-TO-HOST:CONNECT-TO-PORT where HOST is the host of the
39    request, PORT is the port of the request, CONNECT-TO-HOST is the host name
40    to connect to, and CONNECT-TO-PORT is the port to connect to.
41   */
42  /* instead of curl.se:443, it will resolve and use example.com:443 but in
43     other aspects work as if it still is curl.se */
44  struct curl_slist *host = curl_slist_append(NULL,
45                                              "curl.se:443:example.com:443");
46
47  curl = curl_easy_init();
48  if(curl) {
49    curl_easy_setopt(curl, CURLOPT_CONNECT_TO, host);
50    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
51    curl_easy_setopt(curl, CURLOPT_URL, "https://curl.se/");
52
53    /* since this connects to the wrong host, checking the host name in the
54       server certificate will fail, so unless we disable the check libcurl
55       returns CURLE_PEER_FAILED_VERIFICATION */
56    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
57
58    /* Letting the wrong host name in the certificate be okay, the transfer
59       goes through but will (most likely) cause a 404 or similar because it
60       sends an unknown name in the Host: header field */
61    res = curl_easy_perform(curl);
62
63    /* always cleanup */
64    curl_easy_cleanup(curl);
65  }
66
67  curl_slist_free_all(host);
68
69  return (int)res;
70}
71