CURLOPT_PREREQFUNCTION

CURLOPT_PREREQFUNCTION is one of the accepted parameters for curl_setopt parameter #2.

CURLOPT_PREREQFUNCTION — A callable with the following signature that gets called after the connection is established, but before the request payload (for example, the GET/POST/DELETE request of an HTTP connection) is sent, and can be used to abort or allow the connection depending on the source and destination IP address and port numbers:

 Return [`CURL_PREREQFUNC_OK`](/codex/CURL_PREREQFUNC_OK) to allow the request, or
 [`CURL_PREREQFUNC_ABORT`](/codex/CURL_PREREQFUNC_ABORT) to abort the transfer.
 Available as of PHP 8.4.0 and cURL 7.80.0.

CURLOPT_PREREQFUNCTION = 20312;