php判断来源网址地址并且限制非法来源

$fromHost = array(
'paipai.com',
'localhost',
'127.0.0.1'
);
$s = 'http://www.paipai.Com/chong/abc.shtml';
$urlArr = parse_url($s);
$host = isset($urlArr['host'])?$urlArr['host']:'';
$host = strtolower(str_ireplace('www.','',$host));
echo $host.'-->';
echo in_array($host,$fromHost)?'允许通过':'非法来源';

　　//$referer 为来源网址

$referer = $_SERVER['HTTP_REFERER'];