curl / libcurl / API / curl_easy_setopt / CURLOPT_SOCKOPTDATA

CURLOPT_SOCKOPTDATA explained

Name

CURLOPT_SOCKOPTDATA - pointer to pass to sockopt callback

Synopsis

#include <curl/curl.h>
 
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SOCKOPTDATA, void *pointer);

Description

Pass a pointer that is untouched by libcurl and passed as the first argument in the sockopt callback set with CURLOPT_SOCKOPTFUNCTION.

Default

NULL

Protocols

This functionality affects all supported protocols

Example

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);
  }
}

Availability

Added in curl 7.16.0

Return value

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.