来自$ _GET的特殊字符使用php

I'm trying to get text entered from url

my php contains

<?php
    $GET = rawurlencode($_GET[test]);
    print urldecode($GET);
?>

my text http://test.com/forum/forum.php?mod=viewthread&tid=27&extra=page%3D1

but it won't get the whole url... please help how to get full url

---edit--- to make my question more clearly

here is what i'll input in the url

http://test.com/redirect.php?test=http://test.com/forum/forum.php?mod=viewthread&tid=27&extra=page%3D1

and i want to get

http://test.com/forum/forum.php?mod=viewthread&tid=27&extra=page%3D1

your code can work normally, but I think there's a problem with $_GET[test] since it should be

$_GET['test']

May be it will be helpfull

    <?php
     $uri=rawurldecode($_GET['test']);
     echo $uri;

I figured it out, needed some string manipulation

<?php

$URL='http://'.$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];
$pieces = explode("?test=", $URL);
echo $pieces[1];
?>