<?php
if(isset($_GET['url']))
{
switch($_GET['url'])
{
case "test":
header("location:http://google.ru");
break;
case "test2":
header("location:http://yandex.ru");
break;
default:
header("location:http://google.ru?error");
break;
}
}
?>
<form>
<input type="text" name="url">
</form>