pop3-tls.c (3545B)
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 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 }