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    1: /***************************************************************************
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    3:  *  Project                     ___| | | |  _ \| |
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    7:  *
    8:  * Copyright (C) 1998 - 2016, 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.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: 
   23: /* <DESC>
   24:  * POP3 example using TLS
   25:  * </DESC>
   26:  */
   27: 
   28: #include <stdio.h>
   29: #include <curl/curl.h>
   30: 
   31: /* This is a simple example showing how to retrieve mail using libcurl's POP3
   32:  * capabilities. It builds on the pop3-retr.c example adding transport
   33:  * security to protect the authentication details from being snooped.
   34:  *
   35:  * Note that this example requires libcurl 7.20.0 or above.
   36:  */
   37: 
   38: int main(void)
   39: {
   40:   CURL *curl;
   41:   CURLcode res = CURLE_OK;
   42: 
   43:   curl = curl_easy_init();
   44:   if(curl) {
   45:     /* Set username and password */
   46:     curl_easy_setopt(curl, CURLOPT_USERNAME, "user");
   47:     curl_easy_setopt(curl, CURLOPT_PASSWORD, "secret");
   48: 
   49:     /* This will retrieve message 1 from the user's mailbox */
   50:     curl_easy_setopt(curl, CURLOPT_URL, "pop3://pop.example.com/1");
   51: 
   52:     /* In this example, we'll start with a plain text connection, and upgrade
   53:      * to Transport Layer Security (TLS) using the STLS command. Be careful of
   54:      * using CURLUSESSL_TRY here, because if TLS upgrade fails, the transfer
   55:      * will continue anyway - see the security discussion in the libcurl
   56:      * tutorial for more details. */
   57:     curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);
   58: 
   59:     /* If your server doesn't have a valid certificate, then you can disable
   60:      * part of the Transport Layer Security protection by setting the
   61:      * CURLOPT_SSL_VERIFYPEER and CURLOPT_SSL_VERIFYHOST options to 0 (false).
   62:      *   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
   63:      *   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
   64:      *
   65:      * That is, in general, a bad idea. It is still better than sending your
   66:      * authentication details in plain text though.  Instead, you should get
   67:      * the issuer certificate (or the host certificate if the certificate is
   68:      * self-signed) and add it to the set of certificates that are known to
   69:      * libcurl using CURLOPT_CAINFO and/or CURLOPT_CAPATH. See docs/SSLCERTS
   70:      * for more information. */
   71:     curl_easy_setopt(curl, CURLOPT_CAINFO, "/path/to/certificate.pem");
   72: 
   73:     /* Since the traffic will be encrypted, it is very useful to turn on debug
   74:      * information within libcurl to see what is happening during the
   75:      * transfer */
   76:     curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
   77: 
   78:     /* Perform the retr */
   79:     res = curl_easy_perform(curl);
   80: 
   81:     /* Check for errors */
   82:     if(res != CURLE_OK)
   83:       fprintf(stderr, "curl_easy_perform() failed: %s\n",
   84:               curl_easy_strerror(res));
   85: 
   86:     /* Always cleanup */
   87:     curl_easy_cleanup(curl);
   88:   }
   89: 
   90:   return (int)res;
   91: }