PHP anti theft chain code example

Anti-theft chain is a very common web programming skill at present. This paper shows the implementation method of PHP anti-theft chain with an example. Share it with you for your reference. The specific methods are as follows:

The main function codes are as follows:

<?php
/*
 Usage : Save the above code as dao4.php,
 For example, for testing validatecode.rar At the site http://www.XXXX.com Inside ,
 The download connection is represented by the following code .
 Filename ?site=1&file= Documents  
 For example, the following URL : 
http://www.XXXX.cn/dao4.php?site=1&file=validatecode.rar 
*/
$ADMIN[defaulturl] = "http://www.XXXX.com/404.htm"; // The address returned by the stolen chain 
$okaysites = array(
  "http://www.XXXX.com/",
  "http://XXXX.com"
); // White list 
$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]");
}
?>

I hope this article is helpful for everyone to learn PHP programming.