examples: Updated SMTP MAIL example to use a read function for data

 * Note that this example requires libcurl 7.20.0 or above.

 */

#define FROM    "<sender@example.org>"

#define TO      "<addressee@example.net>"

#define CC      "<info@example.org>"

static const char *payload_text[] = {

  "Date: Mon, 29 Nov 2010 21:54:29 +1100\r\n",

  "To: " TO "\r\n",

  "From: " FROM "(Example User)\r\n",

  "Cc: " CC "(Another example User)\r\n",

  "Message-ID: <dcd7cb36-11db-487a-9f3a-e652a9458efd@rfcpedant.example.org>\r\n",

  "Subject: SMTP example message\r\n",

  "\r\n", /* empty line to divide headers from body, see RFC5322 */

  "The body of the message starts here.\r\n",

  "\r\n",

  "It could be a lot of lines, could be MIME encoded, whatever.\r\n",

  "Check RFC5322.\r\n",

  NULL

};

struct upload_status {

  int lines_read;

};

static size_t payload_source(void *ptr, size_t size, size_t nmemb, void *userp)

{

  struct upload_status *upload_ctx = (struct upload_status *)userp;

  const char *data;

  if((size == 0) || (nmemb == 0) || ((size*nmemb) < 1)) {

    return 0;

  }

  data = payload_text[upload_ctx->lines_read];

  if(data) {

    size_t len = strlen(data);

    memcpy(ptr, data, len);

    upload_ctx->lines_read++;

    return len;

  }

  return 0;

}

int main(void)

{

  CURL *curl;

  CURLcode res;

  CURLcode res = CURLE_OK;

  struct curl_slist *recipients = NULL;

  struct upload_status upload_ctx;

  /* value for envelope reverse-path */

  static const char *from = "<bradh@example.com>";

  /* this becomes the envelope forward-path */

  static const char *to = "<bradh@example.net>";

  upload_ctx.lines_read = 0;

  curl = curl_easy_init();

  if(curl) {

    curl_easy_setopt(curl, CURLOPT_URL, "smtp://mail.example.com");

    /* Note that this option isn't strictly required, omitting it will result in

     * libcurl will sent the MAIL FROM command with no sender data. All

     * 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);

    curl_easy_setopt(curl, CURLOPT_MAIL_FROM, FROM);

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

    recipients = curl_slist_append(recipients, to);

    /* Add two recipients, in this particular case they correspond to the

     * To: and Cc: addressees in the header, but they could be any kind of

     * recipient. */

    recipients = curl_slist_append(recipients, TO);

    recipients = curl_slist_append(recipients, CC);

    curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);

    /* You provide the payload (headers and the body of the message) as the

     * "data" element. There are two choices, either:

     * - provide a callback function and specify the function name using the

     * CURLOPT_READFUNCTION option; or

     * - just provide a FILE pointer that can be used to read the data from.

     * The easiest case is just to read from standard input, (which is available

     * as a FILE pointer) as shown here.

     */

    curl_easy_setopt(curl, CURLOPT_READDATA, stdin);

    /* 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);

    /* send the message (including headers) */