Whitelist Incoming IP (midtrans) for Post Notification Payment

whitelist.php

<?php
$RequestIP = (isset($_SERVER['HTTP_CLIENT_IP']) ? $_SERVER['HTTP_CLIENT_IP'] : isset($_SERVER['HTTP_X_FORWARDED_FOR'])) ? $_SERVER['HTTP_X_FORWARDED_FOR'] : $_SERVER['REMOTE_ADDR'];
$IP_MIDTRANS = ['103\.208\..*', '103\.208\..*', '103\.127\..*', '103\.127\..*'];
if(!preg_match('/^(' . implode('|', $IP_MIDTRANS) . ')/', $RequestIP)){
    http_response_code(401);
    return false;
}
?>