A function for proprietary CMS that return

subsiteLink.php

function subsiteLink($subdomain = false) {
    $ret = '';
    $hostAry = explode('.', SITE_HOST);
    if (sizeof($hostAry) == 3 && in_array($subdomain, array('vl', 'lr'))) {
        if ($subdomain) {
            // return a link of the requested subdomain
            $ret = implode('.', array($subdomain, $hostAry[1], $hostAry[2]));
        } else  {
            // return a link of the main domain
            $ret = implode('.', array($hostAry[1], $hostAry[2]));
        }
    }
    return 'http://' . $ret;
}