curl_send_message.c

#include "curl_send_message.h"
#include <curl/curl.h>
#include <time.h>

static size_t payload_source(void* ptr, size_t size, size_t nmemb, void* userp) {
  struct upload_status* upload_ctx = (struct upload_status*)userp;
  size_t rdsize = size * nmemb;

  if ((size == 0) || (nmemb == 0) || (rdsize < 1) || (upload_ctx->pos >= upload_ctx->size)) {
    return 0;
  }

  if (rdsize + upload_ctx->pos > upload_ctx->size) {
    rdsize = upload_ctx->size - upload_ctx->pos;
  }

  memcpy(ptr, &upload_ctx->payload[upload_ctx->pos], rdsize);
  upload_ctx->pos += rdsize;

  return rdsize;
}

void send_message(const char* dest, const char* to[], size_t to_size, const char* from, const char* payload,
                  size_t payload_size) {
  CURL* curl;
  CURLcode res;
  struct curl_slist* recipients = NULL;
  struct upload_status upload_ctx;

  upload_ctx.pos = 0;
  upload_ctx.size = payload_size;
  upload_ctx.payload = payload;

  curl = curl_easy_init();
  if (curl) {
    /* This is the URL for your mailserver */
    curl_easy_setopt(curl, CURLOPT_URL, dest);

    curl_easy_setopt(curl, CURLOPT_MAIL_FROM, from);

    /* Note that the CURLOPT_MAIL_RCPT takes a list, not a char array.  */

    for (size_t ii = 0; ii < to_size; ++ii) {
      recipients = curl_slist_append(recipients, to[ii]);
    }
    curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);

    curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source);
    curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx);
    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);

    /* send the message (including headers) */
    res = curl_easy_perform(curl);

    /* Check for errors */
    if (res != CURLE_OK) fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));

    /* free the list of recipients */
    curl_slist_free_all(recipients);

    curl_easy_cleanup(curl);
  }
}

void send_message_ssl(const char* dest, const char* to[], size_t to_size, const char* from, const char* payload,
                      size_t payload_size, const char* username, const char* pw, int disableVerify) {
  CURL* curl;
  CURLcode res = CURLE_OK;
  struct curl_slist* recipients = NULL;
  struct upload_status upload_ctx;

  upload_ctx.pos = 0;
  upload_ctx.size = payload_size;
  upload_ctx.payload = payload;

  curl = curl_easy_init();
  if (curl) {
    /* Set username and password */
    curl_easy_setopt(curl, CURLOPT_USERNAME, username);
    curl_easy_setopt(curl, CURLOPT_PASSWORD, pw);

    /* This is the URL for your mailserver. Note the use of port 587 here,
     * instead of the normal SMTP port (25). Port 587 is commonly used for
     * secure mail submission (see RFC4403), but you should use whatever
     * matches your server configuration. */
    curl_easy_setopt(curl, CURLOPT_URL, dest);

    /* In this example, we'll start with a plain text connection, and upgrade
     * to Transport Layer Security (TLS) using the STARTTLS command. Be careful
     * of using CURLUSESSL_TRY here, because if TLS upgrade fails, the transfer
     * will continue anyway - see the security discussion in the libcurl
     * tutorial for more details. */
    curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);

    if (disableVerify) {
      curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
      curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
    }

    /* Note that this option isn't strictly required, omitting it will result
     * in libcurl sending the MAIL FROM command with empty sender data. All
     * autoresponses should have an empty reverse-path, and should be directed
     * to the address in the reverse-path which triggered them. Otherwise,
     * they could cause an endless loop. See RFC 5321 Section 4.5.5 for more
     * details.
     */
    curl_easy_setopt(curl, CURLOPT_MAIL_FROM, from);

    for (size_t ii = 0; ii < to_size; ++ii) {
      recipients = curl_slist_append(recipients, to[ii]);
    }
    curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);

    /* We're using a callback function to specify the payload (the headers and
     * body of the message). You could just use the CURLOPT_READDATA option to
     * specify a FILE pointer to read from. */
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source);
    curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx);
    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);

    /* Since the traffic will be encrypted, it is very useful to turn on debug
     * information within libcurl to see what is happening during the transfer.
     */
    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);

    /* Send the message */
    res = curl_easy_perform(curl);

    /* Check for errors */
    if (res != CURLE_OK) fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));

    /* Free the list of recipients */
    curl_slist_free_all(recipients);

    /* Always cleanup */
    curl_easy_cleanup(curl);
  }
}