Free PHP URL shortener script that kicks ass

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

<?php
/*
 * First authored by Brian Cray
 * License: http://creativecommons.org/licenses/by/3.0/
 * Contact the author at http://briancray.com/
 */
 
$url_to_shorten
=
get_magic_quotes_gpc() ? stripslashes(trim($_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;
}

<?php
/*
 * First authored by Brian Cray
 * License: http://creativecommons.org/licenses/by/3.0/
 * Contact the author at http://briancray.com/
 */
 
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;
}

<?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/');

DirectoryIndex index.php
 
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>