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curl_ws_send(3) libcurl 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
needs to be zero in subsequent calls.
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_setopt(3), curl_easy_perform(3), curl_easy_getinfo(3),
curl_ws_recv(3), libcurl-ws(3)
libcurl 8.5.0 December 4, 2023 curl_ws_send(3)