xref: /curl/docs/examples/imap-tls.c (revision f540e43b)
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8  * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
9  *
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21  * SPDX-License-Identifier: curl
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24 
25 /* <DESC>
26  * IMAP 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 fetch mail using libcurl's IMAP
34  * capabilities. It builds on the imap-fetch.c example adding transport
35  * security to protect the authentication details from being snooped.
36  *
37  * Note that this example requires libcurl 7.30.0 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 fetches message 1 from the user's inbox */
52     curl_easy_setopt(curl, CURLOPT_URL,
53                      "imap://imap.example.com/INBOX/;UID=1");
54 
55     /* In this example, we start with a plain text connection, and upgrade to
56      * Transport Layer Security (TLS) using the STARTTLS command. Be careful
57      * of using CURLUSESSL_TRY here, because if TLS upgrade fails, the
58      * transfer continues anyway - see the security discussion in the libcurl
59      * tutorial for more details. */
60     curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);
61 
62     /* If your server does not have a valid certificate, then you can disable
63      * part of the Transport Layer Security protection by setting the
64      * CURLOPT_SSL_VERIFYPEER and CURLOPT_SSL_VERIFYHOST options to 0 (false).
65      *   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
66      *   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
67      *
68      * That is, in general, a bad idea. It is still better than sending your
69      * authentication details in plain text though.  Instead, you should get
70      * the issuer certificate (or the host certificate if the certificate is
71      * self-signed) and add it to the set of certificates that are known to
72      * libcurl using CURLOPT_CAINFO and/or CURLOPT_CAPATH. See docs/SSLCERTS
73      * for more information. */
74     curl_easy_setopt(curl, CURLOPT_CAINFO, "/path/to/certificate.pem");
75 
76     /* Since the traffic is encrypted, it is useful to turn on debug
77      * information within libcurl to see what is happening during the
78      * transfer */
79     curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
80 
81     /* Perform the fetch */
82     res = curl_easy_perform(curl);
83 
84     /* Check for errors */
85     if(res != CURLE_OK)
86       fprintf(stderr, "curl_easy_perform() failed: %s\n",
87               curl_easy_strerror(res));
88 
89     /* Always cleanup */
90     curl_easy_cleanup(curl);
91   }
92 
93   return (int)res;
94 }
95