PHP link control system - php

Question

I have a question about "link control system" in PHP. The idea is to make script that could make different links than original - something like friendly links with .htaccess. In .htaccess make rule to redirect all traffic to script file - for example linkprocessor.php then in this file should be some conditions, mysql connect and pattern grabber from database(friendlyurl and originalurl columns). So if we write full address - example.com/defined-address it will redirect us(but not change address) to linkprocessor.php and then script is checking if /defined-address is in database, if is it will include certain(based on friendlyurl) originalurl file. Is that script would be optimal? That script could prevent from "hackers".
Example:
example.com/defined-address -> linkprocessor.php -> SELECT originalurl from table WHERE friendlyurl = /defined-address -> include originalurl
=> can be written incoherently but its hard to explain that precisely

Answer 1

What you are asking about here is the Front Controller pattern http://en.wikipedia.org/wiki/Front_controller.
There are various ways to implement it, using a sql database to map URI strings to files to include is a valid way to do it, but might be overkill. The same information could probably be hard coded in a php array.
The standard way to prevent hackers is to only allow whitelisted files to be included. In your case you are using an explicit map to determine which page to include, so it is not an issue.
Some code to get you started:
<?php
$map = array('/home' => 'included_1', '/details' => 'included_2' ... )
if (array_key_exists($_SERVER['REQUEST_URI'], $map)) {
include $map[$_SERVER['REQUEST_URI']]
}
else {
// Send a 404 response
}

Answer 2

What you're looking for is the Front End Controller design pattern.
You described the basic method for solving this, which is to redirect all incoming requests (minus requests for static content such as images, CSS files and JS files) to a single file. Generally this file is the index.php file in the site's root directory, but can be any file.
You can accomplish this redirection using .htaccess on Apache servers or web.config on IIS servers. For .htaccess you can google mod_rewrite and get a load of information that will help you along.
Once you have all of the requests being directed to your Front End Controller, you need to determine what the request is asking for. You can inspect PHP's $_SERVER['REQUEST_URI'] to see what the request is, and handle it accordingly.
The most extensible solutions to this problem that I've seen rely on controllers (classes) being in a specific location and 'static' files being in a separate location. Doing something like the following would make it trivially easy to extend the requests that your site will respond to:
/**
I am assuming at this point that the variable $request is an array
representing the current request. For example, if the request is for:
http://www.example.com/dir/page, $request will contain two entries,
'dir' and 'page'
**/
if(file_exists('/controllers/' . $request[0] . '.php')) {
require_once '/controllers/' . $request[0] . '.php';
$controller = new $request[0]();
$controller->dispatch($request);
} else if(file_exists( '/static/'.$request[0] . '.php')) {
require_once '/static/' . $request[0] . '.php';
} else
throw new Exception('404', 404);
The above is more pseudo-code than actual code, I won't guarantee that it will actually run but the idea is there.
To add another controller to your system, you would simply write a class, make sure that it has a dispatch method, and put it in the proper location.