174 lines
6.3 KiB
C
174 lines
6.3 KiB
C
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/***************************************************************************
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* _ _ ____ _
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* Project ___| | | | _ \| |
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* / __| | | | |_) | |
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* | (__| |_| | _ <| |___
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* \___|\___/|_| \_\_____|
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*
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* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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*
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* This software is licensed as described in the file COPYING, which
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* you should have received as part of this distribution. The terms
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* are also available at https://curl.se/docs/copyright.html.
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*
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* You may opt to use, copy, modify, merge, publish, distribute and/or sell
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* copies of the Software, and permit persons to whom the Software is
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* furnished to do so, under the terms of the COPYING file.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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* SPDX-License-Identifier: curl
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*
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***************************************************************************/
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/* <DESC>
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* Send SMTP email using implicit TLS
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* </DESC>
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*/
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#include <stdio.h>
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#include <string.h>
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#include <curl/curl.h>
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/* This is a simple example showing how to send mail using libcurl's SMTP
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* capabilities. It builds on the smtp-mail.c example to add authentication
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* and, more importantly, transport security to protect the authentication
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* details from being snooped.
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*
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* Note that this example requires libcurl 7.20.0 or above.
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*/
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#define FROM_MAIL "<sender@example.com>"
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#define TO_MAIL "<recipient@example.com>"
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#define CC_MAIL "<info@example.com>"
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static const char *payload_text =
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"Date: Mon, 29 Nov 2010 21:54:29 +1100\r\n"
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"To: " TO_MAIL "\r\n"
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"From: " FROM_MAIL "\r\n"
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"Cc: " CC_MAIL "\r\n"
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"Message-ID: <dcd7cb36-11db-487a-9f3a-e652a9458efd@"
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"rfcpedant.example.org>\r\n"
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"Subject: SMTP example message\r\n"
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"\r\n" /* empty line to divide headers from body, see RFC 5322 */
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"The body of the message starts here.\r\n"
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"\r\n"
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"It could be a lot of lines, could be MIME encoded, whatever.\r\n"
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"Check RFC 5322.\r\n";
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struct upload_status {
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size_t bytes_read;
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};
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static size_t payload_source(char *ptr, size_t size, size_t nmemb, void *userp)
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{
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struct upload_status *upload_ctx = (struct upload_status *)userp;
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const char *data;
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size_t room = size * nmemb;
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if((size == 0) || (nmemb == 0) || ((size*nmemb) < 1)) {
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return 0;
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}
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data = &payload_text[upload_ctx->bytes_read];
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if(data) {
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size_t len = strlen(data);
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if(room < len)
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len = room;
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memcpy(ptr, data, len);
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upload_ctx->bytes_read += len;
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return len;
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}
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return 0;
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}
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int main(void)
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{
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CURL *curl;
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CURLcode res = CURLE_OK;
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struct curl_slist *recipients = NULL;
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struct upload_status upload_ctx = { 0 };
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curl = curl_easy_init();
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if(curl) {
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/* Set username and password */
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curl_easy_setopt(curl, CURLOPT_USERNAME, "user");
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curl_easy_setopt(curl, CURLOPT_PASSWORD, "secret");
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/* This is the URL for your mailserver. Note the use of port 587 here,
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* instead of the normal SMTP port (25). Port 587 is commonly used for
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* secure mail submission (see RFC 4403), but you should use whatever
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* matches your server configuration. */
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curl_easy_setopt(curl, CURLOPT_URL, "smtp://mainserver.example.net:587");
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/* In this example, we will start with a plain text connection, and upgrade
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* to Transport Layer Security (TLS) using the STARTTLS command. Be careful
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* of using CURLUSESSL_TRY here, because if TLS upgrade fails, the transfer
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* will continue anyway - see the security discussion in the libcurl
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* tutorial for more details. */
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curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);
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/* If your server does not have a valid certificate, then you can disable
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* part of the Transport Layer Security protection by setting the
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* CURLOPT_SSL_VERIFYPEER and CURLOPT_SSL_VERIFYHOST options to 0 (false).
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* curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
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* curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
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* That is, in general, a bad idea. It is still better than sending your
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* authentication details in plain text though. Instead, you should get
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* the issuer certificate (or the host certificate if the certificate is
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* self-signed) and add it to the set of certificates that are known to
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* libcurl using CURLOPT_CAINFO and/or CURLOPT_CAPATH. See docs/SSLCERTS
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* for more information. */
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curl_easy_setopt(curl, CURLOPT_CAINFO, "/path/to/certificate.pem");
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/* Note that this option is not strictly required, omitting it will result
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* in libcurl sending the MAIL FROM command with empty sender data. All
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* autoresponses should have an empty reverse-path, and should be directed
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* to the address in the reverse-path which triggered them. Otherwise,
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* they could cause an endless loop. See RFC 5321 Section 4.5.5 for more
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* details.
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*/
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curl_easy_setopt(curl, CURLOPT_MAIL_FROM, FROM_MAIL);
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/* Add two recipients, in this particular case they correspond to the
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* To: and Cc: addressees in the header, but they could be any kind of
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* recipient. */
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recipients = curl_slist_append(recipients, TO_MAIL);
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recipients = curl_slist_append(recipients, CC_MAIL);
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curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
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/* We are using a callback function to specify the payload (the headers and
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* body of the message). You could just use the CURLOPT_READDATA option to
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* specify a FILE pointer to read from. */
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curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source);
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curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx);
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curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
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/* Since the traffic will be encrypted, it is useful to turn on debug
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* information within libcurl to see what is happening during the
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* transfer.
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*/
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curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
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/* Send the message */
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res = curl_easy_perform(curl);
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/* Check for errors */
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if(res != CURLE_OK)
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fprintf(stderr, "curl_easy_perform() failed: %s\n",
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curl_easy_strerror(res));
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/* Free the list of recipients */
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curl_slist_free_all(recipients);
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/* Always cleanup */
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curl_easy_cleanup(curl);
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}
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return (int)res;
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}
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