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
25 /* <DESC>
26 * POP3 using TLS
27 * </DESC>
28 */
29
30 #include <stdio.h>
31 #include <curl/curl.h>
32
33 /* This is a simple example showing how to retrieve mail using libcurl's POP3
34 * capabilities. It builds on the pop3-retr.c example adding transport
35 * security to protect the authentication details from being snooped.
36 *
37 * Note that this example requires libcurl 7.20.0 or above.
38 */
39
main(void)40 int main(void)
41 {
42 CURL *curl;
43 CURLcode res = CURLE_OK;
44
45 curl = curl_easy_init();
46 if(curl) {
47 /* Set username and password */
48 curl_easy_setopt(curl, CURLOPT_USERNAME, "user");
49 curl_easy_setopt(curl, CURLOPT_PASSWORD, "secret");
50
51 /* This retrieves message 1 from the user's mailbox */
52 curl_easy_setopt(curl, CURLOPT_URL, "pop3://pop.example.com/1");
53
54 /* In this example, we start with a plain text connection, and upgrade to
55 * Transport Layer Security (TLS) using the STLS command. Be careful of
56 * using CURLUSESSL_TRY here, because if TLS upgrade fails, the transfer
57 * continues anyway - see the security discussion in the libcurl tutorial
58 * for more details. */
59 curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);
60
61 /* If your server does not have a valid certificate, then you can disable
62 * part of the Transport Layer Security protection by setting the
63 * CURLOPT_SSL_VERIFYPEER and CURLOPT_SSL_VERIFYHOST options to 0 (false).
64 * curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
65 * curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
66 *
67 * That is, in general, a bad idea. It is still better than sending your
68 * authentication details in plain text though. Instead, you should get
69 * the issuer certificate (or the host certificate if the certificate is
70 * self-signed) and add it to the set of certificates that are known to
71 * libcurl using CURLOPT_CAINFO and/or CURLOPT_CAPATH. See docs/SSLCERTS
72 * for more information. */
73 curl_easy_setopt(curl, CURLOPT_CAINFO, "/path/to/certificate.pem");
74
75 /* Since the traffic is encrypted, it is useful to turn on debug
76 * information within libcurl to see what is happening during the
77 * transfer */
78 curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
79
80 /* Perform the retr */
81 res = curl_easy_perform(curl);
82
83 /* Check for errors */
84 if(res != CURLE_OK)
85 fprintf(stderr, "curl_easy_perform() failed: %s\n",
86 curl_easy_strerror(res));
87
88 /* Always cleanup */
89 curl_easy_cleanup(curl);
90 }
91
92 return (int)res;
93 }
94