.\" **************************************************************************
.\" *                                  _   _ ____  _
.\" *  Project                     ___| | | |  _ \| |
.\" *                             / __| | | | |_) | |
.\" *                            | (__| |_| |  _ <| |___
.\" *                             \___|\___/|_| \_\_____|
.\" *
.\" * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
.\" *
.\" * This software is licensed as described in the file COPYING, which
.\" * you should have received as part of this distribution. The terms
.\" * are also available at https://curl.se/docs/copyright.html.
.\" *
.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
.\" * copies of the Software, and permit persons to whom the Software is
.\" * furnished to do so, under the terms of the COPYING file.
.\" *
.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
.\" * KIND, either express or implied.
.\" *
.\" * SPDX-License-Identifier: curl
.\" *
.\" **************************************************************************
.\"
.TH CURLOPT_SOCKOPTDATA 3 "16 Jun 2014" libcurl libcurl
.SH NAME
CURLOPT_SOCKOPTDATA \- pointer to pass to sockopt callback
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SOCKOPTDATA, void *pointer);
.fi
.SH DESCRIPTION
Pass a \fIpointer\fP that is untouched by libcurl and passed as the first
argument in the sockopt callback set with \fICURLOPT_SOCKOPTFUNCTION(3)\fP.
.SH DEFAULT
The default value of this parameter is NULL.
.SH PROTOCOLS
All
.SH EXAMPLE
.nf
static int sockopt_callback(void *clientp, curl_socket_t curlfd,
                            curlsocktype purpose)
{
  int val = *(int *)clientp;
  setsockopt((int)curlfd, SOL_SOCKET, SO_RCVBUF,
             (const char *)&val, sizeof(val));
  return CURL_SOCKOPT_OK;
}

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    int recvbuffersize = 256 * 1024;

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

    /* call this function to set options for the socket */
    curl_easy_setopt(curl, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);
    curl_easy_setopt(curl, CURLOPT_SOCKOPTDATA, &recvbuffersize);

    res = curl_easy_perform(curl);

    curl_easy_cleanup(curl);
  }
}
.fi
.SH AVAILABILITY
Added in 7.16.0
.SH RETURN VALUE
Returns \fICURLE_OK\fP if the option is supported, and \fICURLE_UNKNOWN_OPTION\fP if not.
.SH "SEE ALSO"
.BR CURLOPT_OPENSOCKETFUNCTION (3),
.BR CURLOPT_SOCKOPTFUNCTION (3)