xref: /aosp_15_r20/external/curl/docs/libcurl/curl_ws_recv.md (revision 6236dae45794135f37c4eb022389c904c8b0090d)

---
c: Copyright (C) Daniel Stenberg, <[email protected]>, et al.
SPDX-License-Identifier: curl
Title: curl_ws_recv
Section: 3
Source: libcurl
See-also:
  - curl_easy_getinfo (3)
  - curl_easy_perform (3)
  - curl_easy_setopt (3)
  - curl_ws_send (3)
  - libcurl-ws (3)
Protocol:
  - WS
Added-in: 7.86.0
---

# NAME

curl_ws_recv - receive WebSocket data

# SYNOPSIS

~~~c
#include <curl/curl.h>

CURLcode curl_ws_recv(CURL *curl, void *buffer, size_t buflen,
                      size_t *recv, const struct curl_ws_frame **meta);
~~~

# DESCRIPTION

This function call is EXPERIMENTAL.

Retrieves as much as possible of a received WebSocket data fragment into the
**buffer**, but not more than **buflen** bytes. *recv* is set to the
number of bytes actually stored.

If there is more fragment data to deliver than what fits in the provided
*buffer*, libcurl returns a full buffer and the application needs to call this
function again to continue draining the buffer.

If the function call is successful, the *meta* pointer gets set to point to a
*const struct curl_ws_frame* that contains information about the received
data. That struct must not be freed and its contents must not be relied upon
anymore once another WebSocket function is called. See the curl_ws_meta(3) for
details on that struct.a

# %PROTOCOLS%

# EXAMPLE

~~~c
int main(void)
{
  size_t rlen;
  const struct curl_ws_frame *meta;
  char buffer[256];
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res = curl_ws_recv(curl, buffer, sizeof(buffer), &rlen, &meta);
    if(res)
      printf("error: %s\n", curl_easy_strerror(res));
  }
}
~~~

# %AVAILABILITY%

# RETURN VALUE

Returns **CURLE_OK** if everything is okay, and a non-zero number for
errors. Returns **CURLE_GOT_NOTHING** if the associated connection is
closed.

Instead of blocking, the function returns **CURLE_AGAIN**. The correct
behavior is then to wait for the socket to signal readability before calling
this function again.