Route static subdomains to controllers in zend framework

subroute.php

        if (PHP_SAPI != 'cli') //subdomain routing
        {
            $domainname = $this->getOption('domainname');
            $subdomains = $this->getOption('subdomains');
            $router = $this->bootstrap('frontController')->getResource('frontController')->getRouter();
            
            // routes for mainsite (default router is added)
            $wwwRoute = new Zend_Controller_Router_Route_Hostname(
                $domainname,
                array('module' => 'default')
            );
            $router->addRoute(
                'default', 
                $wwwRoute->chain(
                    new Zend_Controller_Router_Route(
                        ':controller/:action/*', 
                        array('controller'=>'index', 'action'=>'index')
                    )
                )
            );
            
            // routes for subdomains (xyz.domain => subxyzController)
            foreach ($subdomains as $subdomain)
            {
                $subdomainRoute = new Zend_Controller_Router_Route_Hostname(
                    $subdomain.'.'.$domainname,
                    array('module' => 'default', 'controller'=>'sub'.$subdomain)
                );
                $router->addRoute(
                    $subdomain,
                    $subdomainRoute->chain(
                        new Zend_Controller_Router_Route(
                            '/:action/*', 
                            array('action'=>'index')
                        )
                    )
                );
            }
        }