CURLOPT_PREREQDATA explained

Name

CURLOPT_PREREQDATA - pointer passed to the pre-request callback

Synopsis

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

Description

Pass a pointer that is untouched by libcurl and passed as the first argument in the pre-request callback set with CURLOPT_PREREQFUNCTION.

Default

NULL

Protocols

This functionality affects all supported protocols

Example

struct priv {
  void *custom;
};
 
static int prereq_callback(void *clientp,
                           char *conn_primary_ip,
                           char *conn_local_ip,
                           int conn_primary_port,
                           int conn_local_port)
{
  printf("Connection made to %s:%d\n", conn_primary_ip, conn_primary_port);
  return CURL_PREREQFUNC_OK;
}
 
int main(void)
{
  struct priv prereq_data;
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_PREREQFUNCTION, prereq_callback);
    curl_easy_setopt(curl, CURLOPT_PREREQDATA, &prereq_data);
    curl_easy_perform(curl);
  }
}

Availability

Added in curl 7.80.0

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.