NAME

       curl_easy_send - sends raw data over an "easy" connection

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_send(CURL *curl, const void *buffer,
                               size_t buflen, size_t *n);

DESCRIPTION

       This  function  sends  arbitrary  data  over  the  established  connection.  You may use it together with
       curl_easy_recv(3) to implement custom protocols using libcurl. This  functionality  can  be  particularly
       useful  if  you use proxies and/or SSL encryption: libcurl takes care of proxy negotiation and connection
       setup.

       buffer is a pointer to the data of length buflen that you want sent. The variable n  points  to  receives
       the number of sent bytes.

       To  establish  the  connection, set CURLOPT_CONNECT_ONLY(3) option before calling curl_easy_perform(3) or
       curl_multi_perform(3). Note that curl_easy_send(3) does not work on connections that were created without
       this option.

       The call returns CURLE_AGAIN if it's not possible to send data right now - the socket  is  used  in  non-
       blocking  mode  internally.  When  CURLE_AGAIN  is  returned,  use  your operating system facilities like
       select(2) to wait until the socket is writable. The socket may  be  obtained  using  curl_easy_getinfo(3)
       with CURLINFO_ACTIVESOCKET(3).

       Furthermore  if  you  wait  on  the  socket  and it tells you it's writable, curl_easy_send(3) may return
       CURLE_AGAIN if the only data that was sent was for internal SSL processing, and no other  data  could  be
       sent.

EXAMPLE

       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           CURLcode res;
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
           /* Do not do the transfer - only connect to host */
           curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
           res = curl_easy_perform(curl);

           if(res == CURLE_OK) {
             long sockfd;
             size_t sent;
             /* Extract the socket from the curl handle - we need it for waiting. */
             res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);

             /* send data */
             res = curl_easy_send(curl, "hello", 5, &sent);
           }
         }
       }

AVAILABILITY

       Added in 7.18.2.

RETURN VALUE

       On  success, returns CURLE_OK and stores the number of bytes actually sent into *n. Note that this may be
       less than the amount you wanted to send.

       On failure, returns the appropriate error code.

       This function may return CURLE_AGAIN. In this case, use your operating system facilities  to  wait  until
       the socket is writable, and retry.

       If   there   is   no  socket  available  to  use  from  the  previous  transfer,  this  function  returns
       CURLE_UNSUPPORTED_PROTOCOL.

SEE ALSO

       curl_easy_setopt(3), curl_easy_perform(3), curl_easy_getinfo(3), curl_easy_recv(3)

libcurl 8.5.0                                   December 04, 2023                              curl_easy_send(3)