Securing Links
About the Author
Mike Rogers is a Web Developer who is currently at University studying Web Technologies. He also is the founder of Full On Design.
He has several years experience freelancing and you can follow him on Twitter (Rogem002).
Have you ever wanted to secure links on your website (for example hide the real source of a file)? Here is a quick and easy way to do this.
<?php # File created on 11th February 2009 by Mike Rogers (http://www.fullondesign.co.uk/).
## Start defining constants ##
define(RUN_ERRORS, TRUE); // Do you want the script to display errors? TRUE = yes you do.
define(redirect_or_echo, 'redirect'); // Do you want to redirect the user to another website, or just echo the other other webpages' content. 'rediect' will redirect, 'echo' will return the web pages constents. I recommend redirect.
## End defining constants ##
/* Start the link codes. The code is the ?code=123 part of the URL. The array should be fotmatted like:
$link['code'] = 'http://URL';
You may find it easier to do this with MySQL or including this as a seperate file. Too many links could lower performance, but for a small website just trying to cloak a few links this is good 
*/
$link['1'] = 'http://www.site.com/';
// Start the system.
function external_url($url){
if($return = @file_get_contents($url)){
return $return;
}elseif(function_exists("curl_init")){
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_TIMEOUT, 10);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$return = curl_exec($ch);
curl_close($ch);
return $return;
}elseif($return = @implode("", @file($url))){
return $return;
} else {
return NULL;
}
}
// Checks if the code is a number
if(is_numeric($_GET['code']) && is_array($link)){
if(isset($link[$_GET['code']])){
if(redirect_or_echo === 'redirect'){
header('location: '.$link[$_GET['code']]);
} elseif(redirect_or_echo === 'echo'){
echo external_url($link[$_GET['code']]);
}else{
if(RUN_ERRORS === TRUE){
echo 'Sorry, an internal error has occoured.';
}
}
} else {
if(RUN_ERRORS === TRUE){
echo 'Sorry, the code you have provided is incorrect.';
}
}
}else{
if(RUN_ERRORS === TRUE){
echo 'Sorry, the code you have provided is incorrect.';
}
}
/*
You are free to share, modify and use this code for commercial uses. Please give a link back (to http://www.fullondesign.co.uk/ ) if you can, but you don't have you.
You use this at your own risk.
*/
?>
Download the Code
Useful Links
PHP’s Offical Website – It has a fantastic documentation section. Well worth a look.
PHP 6 and MySQL 5 for Dynamic Web Sites: Visual QuickPro Guide
– The book I learnt PHP from, it’s really good for beginners and reference guide.
Posted February 14th, 2009
Leave a Reply
