Subdomain Finder

<?php
set_time_limit(0);

$domain = $_GET['domain'];

function curl($url, $post=null) {
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Windows NT 6.3; rv:50.0) Gecko/20100101 Firefox/50.0");
    if($post != null) {
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
    }
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    $exec = curl_exec($ch);
    curl_close($ch);
    return $exec;
}

if(!empty($domain)) {
    $find = curl("https://findsubdomains.com/subdomains-map/".$domain);
    if(preg_match("/Page not found/i", $find)) exit("Domain tidak ditemukan!");
    else{
        preg_match("/var data = ([^']+);/i", $find, $data);
        $data = explode("\n// create a name: node map", $data[1])[0];
        $data = str_replace(array(" ",";"), "", $data);
        $data = str_replace(",]", "]", $data);

        $json = json_decode($data);
        foreach($json as $subdo) {
            if($subdo->name !== "") echo $subdo->name."<br>";
        }
    }
}else exit("Parameter domain masih kosong!");