PHP DNS AMP SCANNER BY SYNTHMESC [CONSOLE VERSION]

<?php

$file = "dnsservers.txt";

$handle = fopen($file, "r");
if ($handle) {
    while (($server = fgets($handle)) !== false) {
        $server = str_replace("\n", "", $server); //remove trailing \n
        checkForRecursion($server);
    }

    fclose($handle);
} else {
    // error opening the file.
    echo "Failed to open file $file\n";
    die;
}


function checkForRecursion($target) {
    $request = "\xde\xad"; // Transaction-ID 0xdead
    $request .= "\x01\x00"; // flags (recursion desired)
    $request .= "\x00\x01"; // 1 question
    $request .= "\x00\x00"; // 0 answers
    $request .= "\x00\x00"; // 0 authority
    $request .= "\x00\x00"; // 0 additional
    $request .= "\x03www\x09wikipedia\x03org\x00"; // www.wikipedia.org
    $request .= "\x00\x01"; // type A
    $request .= "\x00\x01"; // class IN

    $sock = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);

    socket_set_option($sock,SOL_SOCKET,SO_RCVTIMEO,array("sec"=>0,"usec"=>500000));

    $len = strlen($request);
    $port = 53;
    socket_sendto($sock, $request, $len, 0, $target, $port);
    $r = socket_recvfrom($sock, $response, 1024, 0, $target, $port);

    if ($response[3] == "\x80") {
        echo "[+] Recursion appears to be enabled on $target!\n";
        $logfile="recursive.txt";
        $fp = fopen($logfile, "a") or die("Unable to open file!");  fwrite($fp, $target . "\r\n") or die("Unable to write to file!");
        fflush($fp);
fclose($fp);
        return true;
    } else if ($response == "") {
        echo "[-] No response from $target.\n";
        return false;
    } else {
        echo "[-] Recursion appears to be disabled on $target.\n";
        return false;
    }
    socket_close($sock);
}
?>