curl_ws_send(3)            Library Functions Manual            curl_ws_send(3)

NAME
       curl_ws_send - send WebSocket data

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_ws_send(CURL *curl, const void *buffer, size_t buflen,
                             size_t *sent, curl_off_t fragsize,
                             unsigned int flags);

DESCRIPTION
       This function call is EXPERIMENTAL.

       Send the specific message fragment over an established WebSocket
       connection. The buffer holds the data to send and it is buflen number
       of payload bytes in that memory area.

       sent is returned as the number of payload bytes actually sent.

       To send a (huge) fragment using multiple calls with partial content per
       invoke, set the CURLWS_OFFSET bit and the fragsize argument as the
       total expected size for the first part, then set the CURLWS_OFFSET with
       a zero fragsize for the following parts.

       If not sending a partial fragment or if this is raw mode, fragsize
       should be set to zero.

       If CURLWS_RAW_MODE is enabled in CURLOPT_WS_OPTIONS(3), the flags
       argument should be set to 0.

       To send a message consisting of multiple frames, set the CURLWS_CONT
       bit in all frames except the final one.

FLAGS
       CURLWS_TEXT
              The buffer contains text data. Note that this makes a difference
              to WebSocket but libcurl itself does not make any verification
              of the content or precautions that you actually send valid UTF-8
              content.

       CURLWS_BINARY
              This is binary data.

       CURLWS_CONT
              This is not the final fragment of the message, which implies
              that there is another fragment coming as part of the same
              message where this bit is not set.

       CURLWS_CLOSE
              Close this transfer.

       CURLWS_PING
              This is a ping.

       CURLWS_PONG
              This is a pong.

       CURLWS_OFFSET
              The provided data is only a partial fragment and there is more
              coming in a following call to curl_ws_send(). When sending only
              a piece of the fragment like this, the fragsize must be provided
              with the total expected fragment size in the first call and it
              needs to be zero in subsequent calls.

PROTOCOLS
       WS

EXAMPLE
       #include <string.h> /* for strlen */

       const char *send_payload = "magic";

       int main(void)
       {
         size_t sent;
         CURLcode res;
         CURL *curl = curl_easy_init();
         curl_easy_setopt(curl, CURLOPT_URL, "wss://example.com/");
         curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 2L);
         curl_easy_perform(curl);
         res = curl_ws_send(curl, send_payload, strlen(send_payload), &sent, 0,
                            CURLWS_PING);
         curl_easy_cleanup(curl);
         return (int)res;
       }

AVAILABILITY
       Added in 7.86.0.

RETURN VALUE
       CURLE_OK (zero) means that the data was sent properly, non-zero means
       an error occurred as <curl/curl.h> defines. See the libcurl-errors(3)
       man page for the full list with descriptions.

SEE ALSO
       curl_easy_getinfo(3), curl_easy_perform(3), curl_easy_setopt(3),
       curl_ws_recv(3), libcurl-ws(3)

libcurl                          April 26 2024                 curl_ws_send(3)