PHP仿盗链代码

<?php 
/** 
* @author seraphim 
* @copyright 2012 
*/ 
$ADMIN = array( 
'defaulturl'=> 'http://www.xx.com/images/banner-header.gif', //盗链返回的地址 
'url_1' => 'http://www.xx.net/file', 
'url_2' => 'http://www.xx.net/file1', 
); 
$okaysites = array( 
'http://box.baidu.com', 
'http://tieba.baidu.com/p/1493336008', //白名单 
'http://www.xx.com/1.html', 
); 
$reffer = $_SERVER['HTTP_REFERER']; 
if ($reffer) { 
$yes = 0; 
while (list($domain, $subarray) = each($okaysites)) { 
if (ereg($subarray, "$reffer")) { 
$yes = 1; 
} 
} 
$theu = 'url_' . $_GET['site']; 
$file = $_GET['file']; 
if ($ADMIN[$theu] and $yes == 1) { 
header("Location: $ADMIN[$theu]/$file"); 
} else { 
header("Location: $ADMIN[defaulturl]"); 
} 
} else { 
header("Location: $ADMIN[defaulturl]"); 
} 
print_r($_SERVER['HTTP_REFERER']); 
?>