PHP Check If User Is Using Tor

<?php
function IsTorExitPoint(){
if (gethostbyname(ReverseIPOctets($_SERVER['REMOTE_ADDR']).".".$_SERVER['SERVER_PORT'].".".ReverseIPOctets($_SERVER['SERVER_ADDR']).".ip-port.exitlist.torproject.org")=="127.0.0.2") {
return true;
} else {
return false;
}
}
function ReverseIPOctets($inputip){
$ipoc = explode(".",$inputip);
return $ipoc[3].".".$ipoc[2].".".$ipoc[1].".".$ipoc[0];
}
if (IsTorExitPoint()) {
    echo 'You are using TOR!</br>';
}else{
    echo 'You are NOT using TOR!</br>';
}
?>