PHP 301 redirect script

redirect.php

<?php
/**
 * PHP Redirect Script
 * 
 * @author http://johnmorrisonline.com
 */

// Map IDs to URLs
$accepted_ids = array(
  'goog' => 'http://www.google.com',
);

// Die on no ID
if ( !isset( $_GET['id'] ) ) {
  die('Oops. Need an ID');
}

// Set ID
$id = $_GET['id'];

// Die on ID not supported
if ( ! in_array( $id, array_keys( $accepted_ids ) ) ) {
  die('Oops. That ID is not supported.');
}

// Get campaign if set
if ( isset( $_GET['utm_campaign'] ) ) {
  $campaign = $_GET['utm_campaign'];
}

// Create redirect
$redirect = sprintf('%s?q=%s', $accepted_ids[$id], $campaign);

// Run the redirect
//echo $redirect;
header("HTTP/1.1 301 Moved Permanently");
header("Location: {$redirect}");

// Exit
exit;