check white list bots

<?php
set_time_limit(0);
ignore_user_abort(true);
header('Content-Type: text/html; charset=UTF-8');

$dbs = glob("whitebot/*.txt", GLOB_NOSORT);

foreach ($dbs as $db) {
$ip = basename(trim($db), ".txt");
$hostname = gethostbyaddr($ip);
$ip2 = gethostbyname($hostname);
if ($ip != $ip2) {
echo '<span style="color:red;">'.$ip.' '.$ip2.' '.$hostname.'</span><br>';
} else {
echo '<span style="color:green;">'.$ip.' '.$ip2.' '.$hostname.'</span><br>';
}
}

echo 'ok';