一段PHP下载防盗链的代码

$ADMIN[defaulturl] = "http://www.sjlong.com/404.htm";//盗链返回的地址
$okaysites = array("http://www.sjlong.com/","http://chinahtml.com"); //白名单
$ADMIN[url_1] = "http://www.sjlong.com/download/";//下载地点1
$ADMIN[url_2] = "";//下载地点2，以此类推

$reffer = $HTTP_REFERER;
if($reffer) {
$yes = 0;
while(list($domain, $subarray) = each($okaysites)) {
if (ereg($subarray,"$reffer")) {
$yes = 1;
}
}
$theu = "url"."_"."$site";
if ($ADMIN[$theu] AND $yes == 1) {
header("Location: $ADMIN[$theu]/$file");
} else {
header("Location: $ADMIN[defaulturl]");
}
} else {
header("Location: $ADMIN[defaulturl]");
}

?>