/app/code/core/Mage/Core/Controller/Varien/Front.php

<?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@magentocommerce.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magentocommerce.com for more information.
 *
 * @category    Mage
 * @package     Mage_Core
 * @copyright   Copyright (c) 2010 Magento Inc. (http://www.magentocommerce.com)
 * @license     http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */


class Mage_Core_Controller_Varien_Front extends Varien_Object
{
    protected $_defaults = array();

    /**
     * Available routers array
     *
     * @var array
     */
    protected $_routers = array();

    protected $_urlCache = array();

    const XML_STORE_ROUTERS_PATH = 'web/routers';

    public function setDefault($key, $value=null)
    {
        if (is_array($key)) {
            $this->_defaults = $key;
        } else {
            $this->_defaults[$key] = $value;
        }
        return $this;
    }

    public function getDefault($key=null)
    {
        if (is_null($key)) {
            return $this->_defaults;
        } elseif (isset($this->_defaults[$key])) {
            return $this->_defaults[$key];
        }
        return false;
    }

    /**
     * Retrieve request object
     *
     * @return Mage_Core_Controller_Request_Http
     */
    public function getRequest()
    {
        return Mage::app()->getRequest();
    }

    /**
     * Retrieve response object
     *
     * @return Zend_Controller_Response_Http
     */
    public function getResponse()
    {
        return Mage::app()->getResponse();
    }

    /**
     * Adding new router
     *
     * @param   string $name
     * @param   Mage_Core_Controller_Varien_Router_Abstract $router
     * @return  Mage_Core_Controller_Varien_Front
     */
    public function addRouter($name, Mage_Core_Controller_Varien_Router_Abstract $router)
    {
        $router->setFront($this);
        $this->_routers[$name] = $router;
        return $this;
    }

    /**
     * Retrieve router by name
     *
     * @param   string $name
     * @return  Mage_Core_Controller_Varien_Router_Abstract
     */
    public function getRouter($name)
    {
        if (isset($this->_routers[$name])) {
            return $this->_routers[$name];
        }
        return false;
    }

    /**
     * Retrieve routers collection
     *
     * @return array
     */
    public function getRouters()
    {
        return $this->_routers;
    }

    /**
     * Init Fron Controller
     *
     * @return Mage_Core_Controller_Varien_Front
     */
    public function init()
    {
        Mage::dispatchEvent('controller_front_init_before', array('front'=>$this));

        $routersInfo = Mage::app()->getStore()->getConfig(self::XML_STORE_ROUTERS_PATH);

        Varien_Profiler::start('mage::app::init_front_controller::collect_routers');
        foreach ($routersInfo as $routerCode => $routerInfo) {
            if (isset($routerInfo['disabled']) && $routerInfo['disabled']) {
                continue;
            }
            if (isset($routerInfo['class'])) {
                $router = new $routerInfo['class'];
                if (isset($routerInfo['area'])) {
                    $router->collectRoutes($routerInfo['area'], $routerCode);
                }
                $this->addRouter($routerCode, $router);
            }
        }
        Varien_Profiler::stop('mage::app::init_front_controller::collect_routers');

        Mage::dispatchEvent('controller_front_init_routers', array('front'=>$this));

        // Add default router at the last
        $default = new Mage_Core_Controller_Varien_Router_Default();
        $this->addRouter('default', $default);

        return $this;
    }

    public function dispatch()
    {
        $request = $this->getRequest();

        // If pre-configured, check equality of base URL and requested URL
        $this->_checkBaseUrl($request);

        $request->setPathInfo()->setDispatched(false);
        if (!$request->isStraight()) {
            Varien_Profiler::start('mage::dispatch::db_url_rewrite');
            Mage::getModel('core/url_rewrite')->rewrite();
            Varien_Profiler::stop('mage::dispatch::db_url_rewrite');
        }
        Varien_Profiler::start('mage::dispatch::config_url_rewrite');
        $this->rewrite();
        Varien_Profiler::stop('mage::dispatch::config_url_rewrite');
        Varien_Profiler::start('mage::dispatch::routers_match');
        $i = 0;
        while (!$request->isDispatched() && $i++<100) {
            foreach ($this->_routers as $router) {
                if ($router->match($this->getRequest())) {
                    break;
                }
            }
        }
        Varien_Profiler::stop('mage::dispatch::routers_match');
        if ($i>100) {
            Mage::throwException('Front controller reached 100 router match iterations');
        }
        //This event give possibility to launch smth before sending ouptut(Allow cookie setting)
        Mage::dispatchEvent('controller_front_send_response_before', array('front'=>$this));
        Varien_Profiler::start('mage::app::dispatch::send_response');
        $this->getResponse()->sendResponse();
        Varien_Profiler::stop('mage::app::dispatch::send_response');
        Mage::dispatchEvent('controller_front_send_response_after', array('front'=>$this));
        return $this;
    }

    public function getRouterByRoute($routeName)
    {
        // empty route supplied - return base url
        if (empty($routeName)) {
            $router = $this->getRouter('standard');
        } elseif ($this->getRouter('admin')->getFrontNameByRoute($routeName)) {
            // try standard router url assembly
            $router = $this->getRouter('admin');
        } elseif ($this->getRouter('standard')->getFrontNameByRoute($routeName)) {
            // try standard router url assembly
            $router = $this->getRouter('standard');
        } elseif ($router = $this->getRouter($routeName)) {
            // try custom router url assembly
        } else {
            // get default router url
            $router = $this->getRouter('default');
        }

        return $router;
    }

    public function getRouterByFrontName($frontName)
    {
        // empty route supplied - return base url
        if (empty($frontName)) {
            $router = $this->getRouter('standard');
        } elseif ($this->getRouter('admin')->getRouteByFrontName($frontName)) {
            // try standard router url assembly
            $router = $this->getRouter('admin');
        } elseif ($this->getRouter('standard')->getRouteByFrontName($frontName)) {
            // try standard router url assembly
            $router = $this->getRouter('standard');
        } elseif ($router = $this->getRouter($frontName)) {
            // try custom router url assembly
        } else {
            // get default router url
            $router = $this->getRouter('default');
        }

        return $router;
    }

    /**
     * Apply configuration rewrites to current url
     *
     * @return Mage_Core_Controller_Varien_Front
     */
    public function rewrite()
    {
        $request = $this->getRequest();
        $config = Mage::getConfig()->getNode('global/rewrite');
        if (!$config) {
            return;
        }
        foreach ($config->children() as $rewrite) {
            $from = (string)$rewrite->from;
            $to = (string)$rewrite->to;
            if (empty($from) || empty($to)) {
                continue;
            }
            $from = $this->_processRewriteUrl($from);
            $to   = $this->_processRewriteUrl($to);

            $pathInfo = preg_replace($from, $to, $request->getPathInfo());

            if (isset($rewrite->complete)) {
                $request->setPathInfo($pathInfo);
            } else {
                $request->rewritePathInfo($pathInfo);
            }
        }
    }

    /**
     * Replace route name placeholders in url to front name
     *
     * @param   string $url
     * @return  string
     */
    protected function _processRewriteUrl($url)
    {
        $startPos = strpos($url, '{');
        if ($startPos!==false) {
            $endPos = strpos($url, '}');
            $routeName = substr($url, $startPos+1, $endPos-$startPos-1);
            $router = $this->getRouterByRoute($routeName);
            if ($router) {
                $fronName = $router->getFrontNameByRoute($routeName);
                $url = str_replace('{'.$routeName.'}', $fronName, $url);
            }
        }
        return $url;
    }

    /**
     * Auto-redirect to base url (without SID) if the requested url doesn't match it.
     * By default this feature is enabled in configuration.
     *
     * @param Zend_Controller_Request_Http $request
     */
    protected function _checkBaseUrl($request)
    {
        if (!Mage::isInstalled() || $request->getPost()) {
            return;
        }
        if (!Mage::getStoreConfig('web/url/redirect_to_base')) {
            return;
        }

        $baseUrl = Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_WEB, Mage::app()->getStore()->isCurrentlySecure());

        if (!$baseUrl) {
            return;
        }

        $redirectCode = 302;
        if (Mage::getStoreConfig('web/url/redirect_to_base')==301) {
            $redirectCode = 301;
        }

        $uri = @parse_url($baseUrl);
        $host = isset($uri['host']) ? $uri['host'] : '';
        $path = isset($uri['path']) ? $uri['path'] : '';

        $requestUri = $request->getRequestUri() ? $request->getRequestUri() : '/';
        if ($host && $host != $request->getHttpHost() || $path && strpos($requestUri, $path) === false)
        {
            Mage::app()->getFrontController()->getResponse()
                ->setRedirect($baseUrl, $redirectCode)
                ->sendResponse();
            exit;
        }
    }
}