php get domain from url

// Warning: This can be manipulated by hackers!
// If this is problematic, store the domain in a config file

$currentDomain = $_SERVER['SERVER_NAME'];

$url = 'http://google.com/dhasjkdas/sadsdds/sdda/sdads.html';
$parse = parse_url($url);
echo $parse['host']; // prints 'google.com'

echo $_SERVER['SERVER_NAME']; //Outputs www.example.com