curl / libcurl / API / curl_easy_setopt / CURLOPT_RESOLVER_START_DATA

CURLOPT_RESOLVER_START_DATA explained

Name

CURLOPT_RESOLVER_START_DATA - pointer passed to the resolver start callback

Synopsis

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

Description

Pass a pointer is be untouched by libcurl and passed as the third argument in the resolver start callback set with CURLOPT_RESOLVER_START_FUNCTION.

Default

NULL

Protocols

This functionality affects all supported protocols

Example

static int resolver_start_cb(void *resolver_state, void *reserved,
                             void *userdata)
{
  (void)reserved;
  printf("Received resolver_state=%p userdata=%p\n",
         resolver_state, userdata);
  return 0;
}
 
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_RESOLVER_START_FUNCTION, resolver_start_cb);
    curl_easy_setopt(curl, CURLOPT_RESOLVER_START_DATA, curl);
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

Availability

Added in curl 7.59.0

Return value

curl_easy_setopt returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors.