PHP Access Control for arunranga.com Domain - Web Resource

Granting access to the web resource only for the arunranga.com domain and returning XML or HTML content based on the request origin.

<?php

if($_SERVER['HTTP_ORIGIN'] == "http://arunranga.com") {
    header('Access-Control-Allow-Origin: http://arunranga.com');
    header('Content-type: application/xml');
    readfile('arunerDotNetResource.xml');
} else {    
    header('Content-Type: text/html');
    echo "<html>";
    echo "<head>";
    echo "   <title>Another Resource</title>";
    echo "</head>";
    echo "<body>",
         "<p>This resource behaves two-fold:";
    echo "<ul>",
         "<li>If accessed from <code>http://arunranga.com</code> it returns an XML document</li>";
    echo   "<li>If accessed from any other origin including from simply typing in the URL into the browser's address bar,";
    echo   "you get this HTML document</li>", 
         "</ul>",
       "</body>",
     "</html>";
}
?>