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 * Send email on behalf of another user with SMTP
27 * </DESC>
28 */
29
30 #include <stdio.h>
31 #include <string.h>
32 #include <curl/curl.h>
33
34 /*
35 * This is a simple example show how to send an email using libcurl's SMTP
36 * capabilities.
37 *
38 * Note that this example requires libcurl 7.66.0 or above.
39 */
40
41 /* The libcurl options want plain addresses, the viewable headers in the mail
42 * can get a full name as well.
43 */
44 #define FROM_ADDR "<ursel@example.org>"
45 #define SENDER_ADDR "<kurt@example.org>"
46 #define TO_ADDR "<addressee@example.net>"
47
48 #define FROM_MAIL "Ursel " FROM_ADDR
49 #define SENDER_MAIL "Kurt " SENDER_ADDR
50 #define TO_MAIL "A Receiver " TO_ADDR
51
52 static const char *payload_text =
53 "Date: Mon, 29 Nov 2010 21:54:29 +1100\r\n"
54 "To: " TO_MAIL "\r\n"
55 "From: " FROM_MAIL "\r\n"
56 "Sender: " SENDER_MAIL "\r\n"
57 "Message-ID: <dcd7cb36-11db-487a-9f3a-e652a9458efd@"
58 "rfcpedant.example.org>\r\n"
59 "Subject: SMTP example message\r\n"
60 "\r\n" /* empty line to divide headers from body, see RFC 5322 */
61 "The body of the message starts here.\r\n"
62 "\r\n"
63 "It could be a lot of lines, could be MIME encoded, whatever.\r\n"
64 "Check RFC 5322.\r\n";
65
66 struct upload_status {
67 size_t bytes_read;
68 };
69
payload_source(char * ptr,size_t size,size_t nmemb,void * userp)70 static size_t payload_source(char *ptr, size_t size, size_t nmemb, void *userp)
71 {
72 struct upload_status *upload_ctx = (struct upload_status *)userp;
73 const char *data;
74 size_t room = size * nmemb;
75
76 if((size == 0) || (nmemb == 0) || ((size*nmemb) < 1)) {
77 return 0;
78 }
79
80 data = &payload_text[upload_ctx->bytes_read];
81
82 if(data) {
83 size_t len = strlen(data);
84 if(room < len)
85 len = room;
86 memcpy(ptr, data, len);
87 upload_ctx->bytes_read += len;
88
89 return len;
90 }
91
92 return 0;
93 }
94
main(void)95 int main(void)
96 {
97 CURL *curl;
98 CURLcode res = CURLE_OK;
99 struct curl_slist *recipients = NULL;
100 struct upload_status upload_ctx = { 0 };
101
102 curl = curl_easy_init();
103 if(curl) {
104 /* This is the URL for your mailserver. In this example we connect to the
105 smtp-submission port as we require an authenticated connection. */
106 curl_easy_setopt(curl, CURLOPT_URL, "smtp://mail.example.com:587");
107
108 /* Set the username and password */
109 curl_easy_setopt(curl, CURLOPT_USERNAME, "kurt");
110 curl_easy_setopt(curl, CURLOPT_PASSWORD, "xipj3plmq");
111
112 /* Set the authorization identity (identity to act as) */
113 curl_easy_setopt(curl, CURLOPT_SASL_AUTHZID, "ursel");
114
115 /* Force PLAIN authentication */
116 curl_easy_setopt(curl, CURLOPT_LOGIN_OPTIONS, "AUTH=PLAIN");
117
118 /* Note that this option is not strictly required, omitting it results in
119 * libcurl sending the MAIL FROM command with empty sender data. All
120 * autoresponses should have an empty reverse-path, and should be directed
121 * to the address in the reverse-path which triggered them. Otherwise,
122 * they could cause an endless loop. See RFC 5321 Section 4.5.5 for more
123 * details.
124 */
125 curl_easy_setopt(curl, CURLOPT_MAIL_FROM, FROM_ADDR);
126
127 /* Add a recipient, in this particular case it corresponds to the
128 * To: addressee in the header. */
129 recipients = curl_slist_append(recipients, TO_ADDR);
130 curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
131
132 /* We are using a callback function to specify the payload (the headers and
133 * body of the message). You could just use the CURLOPT_READDATA option to
134 * specify a FILE pointer to read from. */
135 curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source);
136 curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx);
137 curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
138
139 /* Send the message */
140 res = curl_easy_perform(curl);
141
142 /* Check for errors */
143 if(res != CURLE_OK)
144 fprintf(stderr, "curl_easy_perform() failed: %s\n",
145 curl_easy_strerror(res));
146
147 /* Free the list of recipients */
148 curl_slist_free_all(recipients);
149
150 /* curl does not send the QUIT command until you call cleanup, so you
151 * should be able to reuse this connection for additional messages
152 * (setting CURLOPT_MAIL_FROM and CURLOPT_MAIL_RCPT as required, and
153 * calling curl_easy_perform() again. It may not be a good idea to keep
154 * the connection open for a long time though (more than a few minutes may
155 * result in the server timing out the connection), and you do want to
156 * clean up in the end.
157 */
158 curl_easy_cleanup(curl);
159 }
160
161 return (int)res;
162 }
163
