Free PHP URL shortener script that kicks ass

Posted August 26, 2009 by Brian Cray

Reading time: About 2 minutes

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After seeing some of the other coding approaches to personal short URL services, I decided to write my own PHP URL shortener script and share it with the world.

Thanks to the help of others, such as Nicolas, Derek Gathright, and Adrien Gibrat I’ve been able to take this script much farther.

Benefits

Can shorten over 42 billion unique URLs in 6 or less characters (it can do more than 12,000,000 in only 4!)
Super duper fast—uses very little server resources
Includes an API so you can create your own short URLs on the fly
Option to turn clickthru tracking on and off
Option to limit usage to 1 IP address for personal use and to prevent spamming from others
Only uses alphanumeric characters so all browsers can interpret the URL
Secure—several data filters in place to prevent SQL injection hacks
Option to check if the URL is real (doesn’t respond with a 404) before shortening
Uses 301 redirects for SEO and analytics yumminess
Option to store a local cache to prevent database queries on every redirect
Option to change the characters allowed in a shortened url

Installation

Make sure your server meets the requirements:
- Optionally you can run this from your current domain or find a short domain
- Apache
- PHP
- MySQL
- Access to run SQL queries for installation
Download a .zip file of the PHP URL shortener script files
Upload the contents of the .zip file to your web server
Update the database info in config.php
Run the SQL included in shortenedurls.sql. Many people use phpMyAdmin for this, if you can’t do it yourself contact your host.
Rename rename.htaccess to .htaccess
If you want to use the caching option, create a directory named cache with permissions 777

Using your personal URL shortener service

To manually shorten URLs open in your web browser the location where you uploaded the files. You should see a form that looks and acts like this.

To programmatically shorten URLs with PHP use the following code:

$shortenedurl = file_get_contents('http://yourdomain.com/shorten.php?longurl=' . urlencode('http://' . $_SERVER['HTTP_HOST']  . '/' . $_SERVER['REQUEST_URI']));

A look at the PHP code for curious programmers

Shorten.php – Script shortens URLs

<?php
/*
 * First authored by Brian Cray
 * License: http://creativecommons.org/licenses/by/3.0/
 * Contact the author at http://briancray.com/
 */
 
ini_set('display_errors', 0);
 
$url_to_shorten = get_magic_quotes_gpc() ? stripslashes(trim($_REQUEST['longurl'])) : trim($_REQUEST['longurl']);
 
if(!empty($url_to_shorten) && preg_match('|^https?://|', $url_to_shorten))
{
	require('config.php');
 
	// check if the client IP is allowed to shorten
	if($_SERVER['REMOTE_ADDR'] != LIMIT_TO_IP)
	{
		die('You are not allowed to shorten URLs with this service.');
	}
 
	// check if the URL is valid
	if(CHECK_URL)
	{
		$ch = curl_init();
		curl_setopt($ch, CURLOPT_URL, $url_to_shorten);
		curl_setopt($ch,  CURLOPT_RETURNTRANSFER, TRUE);
		$response = curl_exec($ch);
		curl_close($handle);
		if(curl_getinfo($ch, CURLINFO_HTTP_CODE) == '404')
		{
			die('Not a valid URL');
		}
	}
 
	// check if the URL has already been shortened
	$already_shortened = mysql_result(mysql_query('SELECT id FROM ' . DB_TABLE. ' WHERE long_url="' . mysql_real_escape_string($url_to_shorten) . '"'), 0, 0);
	if(!empty($already_shortened))
	{
		// URL has already been shortened
		$shortened_url = getShortenedURLFromID($already_shortened);
	}
	else
	{
		// URL not in database, insert
		mysql_query('LOCK TABLES ' . DB_TABLE . ' WRITE;');
		mysql_query('INSERT INTO ' . DB_TABLE . ' (long_url, created, creator) VALUES ("' . mysql_real_escape_string($url_to_shorten) . '", "' . time() . '", "' . mysql_real_escape_string($_SERVER['REMOTE_ADDR']) . '")');
		$shortened_url = getShortenedURLFromID(mysql_insert_id());
		mysql_query('UNLOCK TABLES');
	}
	echo BASE_HREF . $shortened_url;
}
 
function getShortenedURLFromID ($integer, $base = ALLOWED_CHARS)
{
	$length = strlen($base);
	while($integer > $length - 1)
	{
		$out = $base[fmod($integer, $length)] . $out;
		$integer = floor( $integer / $length );
	}
	return $base[$integer] . $out;
}

Redirect.php – Script handles short url redirects

<?php
/*
 * First authored by Brian Cray
 * License: http://creativecommons.org/licenses/by/3.0/
 * Contact the author at http://briancray.com/
 */
 
ini_set('display_errors', 0);
 
if(!preg_match('|^[0-9a-zA-Z]{1,6}$|', $_GET['url']))
{
	die('That is not a valid short url');
}
 
require('config.php');
 
$shortened_id = getIDFromShortenedURL($_GET['url']);
 
if(CACHE)
{
	$long_url = file_get_contents(CACHE_DIR . $shortened_id);
	if(empty($long_url) || !preg_match('|^https?://|', $long_url))
	{
		$long_url = mysql_result(mysql_query('SELECT long_url FROM ' . DB_TABLE . ' WHERE id="' . mysql_real_escape_string($shortened_id) . '"'), 0, 0);
		@mkdir(CACHE_DIR, 0777);
		$handle = fopen(CACHE_DIR . $shortened_id, 'w+');
		fwrite($handle, $long_url);
		fclose($handle);
	}
}
else
{
	$long_url = mysql_result(mysql_query('SELECT long_url FROM ' . DB_TABLE . ' WHERE id="' . mysql_real_escape_string($shortened_id) . '"'), 0, 0);
}
 
if(TRACK)
{
	mysql_query('UPDATE ' . DB_TABLE . ' SET referrals=referrals+1 WHERE id="' . mysql_real_escape_string($shortened_id) . '"');
}
 
header('HTTP/1.1 301 Moved Permanently');
header('Location: ' .  $long_url);
exit;
 
function getIDFromShortenedURL ($string, $base = ALLOWED_CHARS)
{
	$length = strlen($base);
	$size = strlen($string) - 1;
	$string = str_split($string);
	$out = strpos($base, array_pop($string));
	foreach($string as $i => $char)
	{
		$out += strpos($base, $char) * pow($length, $size - $i);
	}
	return $out;
}

config.php – Configures the URL shortener

<?php
/*
 * First authored by Brian Cray
 * License: http://creativecommons.org/licenses/by/3.0/
 * Contact the author at http://briancray.com/
 */
 
// db options
define('DB_NAME', 'your db name');
define('DB_USER', 'your db usernae');
define('DB_PASSWORD', 'your db password');
define('DB_HOST', 'localhost');
define('DB_TABLE', 'shortenedurls');
 
// connect to database
mysql_connect(DB_HOST, DB_USER, DB_PASSWORD);
mysql_select_db(DB_NAME);
 
// base location of script (include trailing slash)
define('BASE_HREF', 'http://' . $_SERVER['HTTP_HOST'] . '/');
 
// change to limit short url creation to a single IP
define('LIMIT_TO_IP', $_SERVER['REMOTE_ADDR']);
 
// change to TRUE to start tracking referrals
define('TRACK', FALSE);
 
// check if URL exists first
define('CHECK_URL', FALSE);
 
// change the shortened URL allowed characters
define('ALLOWED_CHARS', '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ');
 
// do you want to cache?
define('CACHE', TRUE);
 
// if so, where will the cache files be stored? (include trailing slash)
define('CACHE_DIR', dirname(__FILE__) . '/cache/');

.htaccess

DirectoryIndex index.php
 
# remove the next 3 lines if you see a 500 server error
php_flag register_globals off
php_flag magic_quotes_gpc off
php_value display_errors 0
 
FileETag none
ServerSignature Off
 
Options All -Indexes
 
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule ^shorten/(.*)$ shorten.php?longurl=$1 [L]
RewriteRule ^([0-9a-zA-Z]{1,6})$ redirect.php?url=$1 [L]
</IfModule>

License and support

This script is provided as is, without warranty or guarantee, licensed under this creative commons license.

I hope you enjoy!

About the author

Brian Cray is a Columbus, Ohio-based web entrepreneur & consultant. View some of Brian’s work in his portfolio and learn how to make kick ass websites by reading his blog.

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