1 /*************************************************************************** 2 * _ _ ____ _ 3 * Project ___| | | | _ \| | 4 * / __| | | | |_) | | 5 * | (__| |_| | _ <| |___ 6 * \___|\___/|_| \_\_____| 7 * 8 * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel (at) 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 (at) example.org>" 41 #define TO "<addressee (at) example.net>" 42 #define CC "<info (at) 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 } 172
