PHP anti-theft chain function instance code

Today's Internet, the collection of Web sites are very many, many sites like hotlinking/misappropriation of other people's website pictures, so not only violated the network rights, but also caused by the hotlinking of the site consumes a lot of traffic, to the server caused relatively large pressure, this article to introduce how PHP to prevent image theft/hotlinking two ways, You need a friend to refer to.

What is the use of image anti-theft chain? Prevent other websites from stealing your pictures and wasting your valuable traffic.

This article mainly introduces the PHP anti-theft chain implementation method, is very practical skills, the need for friends can refer to the next

Anti-theft chain is a very common web programming technique at present. This article shows an example of how to implement the PHP anti-theft chain. Here's how:<?php

/* use: Save the above code as dao4.php, such as Test Validatecode.rar at the site http://www. Xxxx.com, use the following code to indicate the download connection. File name? site=1&file= files such as the following url:http://www. Xxxx.cn/dao4.php?site=1&file=validatecode.rar */$ADMIN [Defaulturl] = "http://www. Xxxx.com/404.htm "; Hotlinking returns the address $okaysites = Array ("http://www. xxxx.com/"," http://XXXX.com "); Whitelist $admin[url_1] = "http://www. Xxxx.com/download/"; Download location 1$admin[url_2] = "";  Download location 2, and so on $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]");}?