Annotation of embedaddon/curl/docs/examples/smtp-tls.c, revision 1.1.1.1
1.1 misho 1: /***************************************************************************
2: * _ _ ____ _
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7: *
8: * Copyright (C) 1998 - 2019, 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: * SMTP example using TLS
25: * </DESC>
26: */
27:
28: #include <stdio.h>
29: #include <string.h>
30: #include <curl/curl.h>
31:
32: /* This is a simple example showing how to send mail using libcurl's SMTP
33: * capabilities. It builds on the smtp-mail.c example to add authentication
34: * and, more importantly, transport security to protect the authentication
35: * details from being snooped.
36: *
37: * Note that this example requires libcurl 7.20.0 or above.
38: */
39:
40: #define FROM "<sender@example.org>"
41: #define TO "<addressee@example.net>"
42: #define CC "<info@example.org>"
43:
44: static const char *payload_text[] = {
45: "Date: Mon, 29 Nov 2010 21:54:29 +1100\r\n",
46: "To: " TO "\r\n",
47: "From: " FROM " (Example User)\r\n",
48: "Cc: " CC " (Another example User)\r\n",
49: "Message-ID: <dcd7cb36-11db-487a-9f3a-e652a9458efd@"
50: "rfcpedant.example.org>\r\n",
51: "Subject: SMTP TLS example message\r\n",
52: "\r\n", /* empty line to divide headers from body, see RFC5322 */
53: "The body of the message starts here.\r\n",
54: "\r\n",
55: "It could be a lot of lines, could be MIME encoded, whatever.\r\n",
56: "Check RFC5322.\r\n",
57: NULL
58: };
59:
60: struct upload_status {
61: int lines_read;
62: };
63:
64: static size_t payload_source(void *ptr, size_t size, size_t nmemb, void *userp)
65: {
66: struct upload_status *upload_ctx = (struct upload_status *)userp;
67: const char *data;
68:
69: if((size == 0) || (nmemb == 0) || ((size*nmemb) < 1)) {
70: return 0;
71: }
72:
73: data = payload_text[upload_ctx->lines_read];
74:
75: if(data) {
76: size_t len = strlen(data);
77: memcpy(ptr, data, len);
78: upload_ctx->lines_read++;
79:
80: return len;
81: }
82:
83: return 0;
84: }
85:
86: int main(void)
87: {
88: CURL *curl;
89: CURLcode res = CURLE_OK;
90: struct curl_slist *recipients = NULL;
91: struct upload_status upload_ctx;
92:
93: upload_ctx.lines_read = 0;
94:
95: curl = curl_easy_init();
96: if(curl) {
97: /* Set username and password */
98: curl_easy_setopt(curl, CURLOPT_USERNAME, "user");
99: curl_easy_setopt(curl, CURLOPT_PASSWORD, "secret");
100:
101: /* This is the URL for your mailserver. Note the use of port 587 here,
102: * instead of the normal SMTP port (25). Port 587 is commonly used for
103: * secure mail submission (see RFC4403), but you should use whatever
104: * matches your server configuration. */
105: curl_easy_setopt(curl, CURLOPT_URL, "smtp://mainserver.example.net:587");
106:
107: /* In this example, we'll start with a plain text connection, and upgrade
108: * to Transport Layer Security (TLS) using the STARTTLS command. Be careful
109: * of using CURLUSESSL_TRY here, because if TLS upgrade fails, the transfer
110: * will continue anyway - see the security discussion in the libcurl
111: * tutorial for more details. */
112: curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);
113:
114: /* If your server doesn't have a valid certificate, then you can disable
115: * part of the Transport Layer Security protection by setting the
116: * CURLOPT_SSL_VERIFYPEER and CURLOPT_SSL_VERIFYHOST options to 0 (false).
117: * curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
118: * curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
119: * That is, in general, a bad idea. It is still better than sending your
120: * authentication details in plain text though. Instead, you should get
121: * the issuer certificate (or the host certificate if the certificate is
122: * self-signed) and add it to the set of certificates that are known to
123: * libcurl using CURLOPT_CAINFO and/or CURLOPT_CAPATH. See docs/SSLCERTS
124: * for more information. */
125: curl_easy_setopt(curl, CURLOPT_CAINFO, "/path/to/certificate.pem");
126:
127: /* Note that this option isn't strictly required, omitting it will result
128: * in libcurl sending the MAIL FROM command with empty sender data. All
129: * autoresponses should have an empty reverse-path, and should be directed
130: * to the address in the reverse-path which triggered them. Otherwise,
131: * they could cause an endless loop. See RFC 5321 Section 4.5.5 for more
132: * details.
133: */
134: curl_easy_setopt(curl, CURLOPT_MAIL_FROM, FROM);
135:
136: /* Add two recipients, in this particular case they correspond to the
137: * To: and Cc: addressees in the header, but they could be any kind of
138: * recipient. */
139: recipients = curl_slist_append(recipients, TO);
140: recipients = curl_slist_append(recipients, CC);
141: curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
142:
143: /* We're using a callback function to specify the payload (the headers and
144: * body of the message). You could just use the CURLOPT_READDATA option to
145: * specify a FILE pointer to read from. */
146: curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source);
147: curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx);
148: curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
149:
150: /* Since the traffic will be encrypted, it is very useful to turn on debug
151: * information within libcurl to see what is happening during the transfer.
152: */
153: curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
154:
155: /* Send the message */
156: res = curl_easy_perform(curl);
157:
158: /* Check for errors */
159: if(res != CURLE_OK)
160: fprintf(stderr, "curl_easy_perform() failed: %s\n",
161: curl_easy_strerror(res));
162:
163: /* Free the list of recipients */
164: curl_slist_free_all(recipients);
165:
166: /* Always cleanup */
167: curl_easy_cleanup(curl);
168: }
169:
170: return (int)res;
171: }
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