curl/docs/libcurl/opts/CURLOPT_PREREQDATA.md

---

c: Copyright (C) Daniel Stenberg, daniel@haxx.se, et al. SPDX-License-Identifier: curl Title: CURLOPT_PREREQDATA Section: 3 Source: libcurl See-also:

• CURLINFO_PRIMARY_IP (3)
• CURLINFO_PRIMARY_PORT (3)
• CURLOPT_PREREQFUNCTION (3) Protocol:
• All Added-in: 7.80.0 ---

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(3).

DEFAULT

NULL

%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%

RETURN VALUE

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