smtp-ssl.c (5899B)
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 SMTP email using implicit SSL 27 * </DESC> 28 */ 29 30 #include <stdio.h> 31 #include <string.h> 32 #include <curl/curl.h> 33 34 /* This is a simple example showing how to send mail using libcurl's SMTP 35 * capabilities. It builds on the smtp-mail.c example to add authentication 36 * and, more importantly, transport security to protect the authentication 37 * details from being snooped. 38 * 39 * Note that this example requires libcurl 7.20.0 or above. 40 */ 41 42 #define FROM_MAIL "<sender@example.com>" 43 #define TO_MAIL "<recipient@example.com>" 44 #define CC_MAIL "<info@example.com>" 45 46 static const char *payload_text = 47 "Date: Mon, 29 Nov 2010 21:54:29 +1100\r\n" 48 "To: " TO_MAIL "\r\n" 49 "From: " FROM_MAIL "\r\n" 50 "Cc: " CC_MAIL "\r\n" 51 "Message-ID: <dcd7cb36-11db-487a-9f3a-e652a9458efd@" 52 "rfcpedant.example.org>\r\n" 53 "Subject: SMTP example message\r\n" 54 "\r\n" /* empty line to divide headers from body, see RFC 5322 */ 55 "The body of the message starts here.\r\n" 56 "\r\n" 57 "It could be a lot of lines, could be MIME encoded, whatever.\r\n" 58 "Check RFC 5322.\r\n"; 59 60 struct upload_status { 61 size_t bytes_read; 62 }; 63 64 static size_t payload_source(char *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 size_t room = size * nmemb; 69 70 if((size == 0) || (nmemb == 0) || ((size*nmemb) < 1)) { 71 return 0; 72 } 73 74 data = &payload_text[upload_ctx->bytes_read]; 75 76 if(data) { 77 size_t len = strlen(data); 78 if(room < len) 79 len = room; 80 memcpy(ptr, data, len); 81 upload_ctx->bytes_read += len; 82 83 return len; 84 } 85 86 return 0; 87 } 88 89 int main(void) 90 { 91 CURL *curl; 92 CURLcode res = CURLE_OK; 93 struct curl_slist *recipients = NULL; 94 struct upload_status upload_ctx = { 0 }; 95 96 curl = curl_easy_init(); 97 if(curl) { 98 /* Set username and password */ 99 curl_easy_setopt(curl, CURLOPT_USERNAME, "user"); 100 curl_easy_setopt(curl, CURLOPT_PASSWORD, "secret"); 101 102 /* This is the URL for your mailserver. Note the use of smtps:// rather 103 * than smtp:// to request an SSL based connection. */ 104 curl_easy_setopt(curl, CURLOPT_URL, "smtps://mainserver.example.net"); 105 106 /* If you want to connect to a site who is not using a certificate that is 107 * signed by one of the certs in the CA bundle you have, you can skip the 108 * verification of the server's certificate. This makes the connection 109 * A LOT LESS SECURE. 110 * 111 * If you have a CA cert for the server stored someplace else than in the 112 * default bundle, then the CURLOPT_CAPATH option might come handy for 113 * you. */ 114 #ifdef SKIP_PEER_VERIFICATION 115 curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L); 116 #endif 117 118 /* If the site you are connecting to uses a different host name that what 119 * they have mentioned in their server certificate's commonName (or 120 * subjectAltName) fields, libcurl refuses to connect. You can skip this 121 * check, but it makes the connection insecure. */ 122 #ifdef SKIP_HOSTNAME_VERIFICATION 123 curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L); 124 #endif 125 126 /* Note that this option is not strictly required, omitting it results in 127 * libcurl sending the MAIL FROM command with empty sender data. All 128 * autoresponses should have an empty reverse-path, and should be directed 129 * to the address in the reverse-path which triggered them. Otherwise, 130 * they could cause an endless loop. See RFC 5321 Section 4.5.5 for more 131 * details. 132 */ 133 curl_easy_setopt(curl, CURLOPT_MAIL_FROM, FROM_MAIL); 134 135 /* Add two recipients, in this particular case they correspond to the 136 * To: and Cc: addressees in the header, but they could be any kind of 137 * recipient. */ 138 recipients = curl_slist_append(recipients, TO_MAIL); 139 recipients = curl_slist_append(recipients, CC_MAIL); 140 curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients); 141 142 /* We are using a callback function to specify the payload (the headers and 143 * body of the message). You could just use the CURLOPT_READDATA option to 144 * specify a FILE pointer to read from. */ 145 curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source); 146 curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx); 147 curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L); 148 149 /* Since the traffic is encrypted, it is useful to turn on debug 150 * information within libcurl to see what is happening during the 151 * transfer */ 152 curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); 153 154 /* Send the message */ 155 res = curl_easy_perform(curl); 156 157 /* Check for errors */ 158 if(res != CURLE_OK) 159 fprintf(stderr, "curl_easy_perform() failed: %s\n", 160 curl_easy_strerror(res)); 161 162 /* Free the list of recipients */ 163 curl_slist_free_all(recipients); 164 165 /* Always cleanup */ 166 curl_easy_cleanup(curl); 167 } 168 169 return (int)res; 170 }