cakephp/src/Routing/Filter/AssetFilter.php

<?php
/**
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @since         2.2.0
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */
namespace Cake\Routing\Filter;

use Cake\Core\Plugin;
use Cake\Event\Event;
use Cake\Network\Request;
use Cake\Network\Response;
use Cake\Routing\DispatcherFilter;
use Cake\Utility\Inflector;

/**
 * Filters a request and tests whether it is a file in the webroot folder or not and
 * serves the file to the client if appropriate.
 *
 */
class AssetFilter extends DispatcherFilter {

/**
 * Default priority for all methods in this filter
 * This filter should run before the request gets parsed by router
 *
 * @var int
 */
	protected $_priority = 9;

/**
 * Checks if a requested asset exists and sends it to the browser
 *
 * @param \Cake\Event\Event $event containing the request and response object
 * @return \Cake\Network\Response if the client is requesting a recognized asset, null otherwise
 * @throws NotFoundException When asset not found
 */
	public function beforeDispatch(Event $event) {
		$request = $event->data['request'];

		$url = urldecode($request->url);
		if (strpos($url, '..') !== false || strpos($url, '.') === false) {
			return;
		}

		$assetFile = $this->_getAssetFile($url);
		if ($assetFile === null || !file_exists($assetFile)) {
			return null;
		}
		$response = $event->data['response'];
		$event->stopPropagation();

		$response->modified(filemtime($assetFile));
		if ($response->checkNotModified($request)) {
			return $response;
		}

		$pathSegments = explode('.', $url);
		$ext = array_pop($pathSegments);
		$this->_deliverAsset($request, $response, $assetFile, $ext);
		return $response;
	}

/**
 * Builds asset file path based off url
 *
 * @param string $url Asset URL
 * @return string Absolute path for asset file
 */
	protected function _getAssetFile($url) {
		$parts = explode('/', $url);
		$pluginPart = [];
		for ($i = 0; $i < 2; $i++) {
			if (!isset($parts[$i])) {
				break;
			}
			$pluginPart[] = Inflector::camelize($parts[$i]);
			$plugin = implode('/', $pluginPart);
			if ($plugin && Plugin::loaded($plugin)) {
				$parts = array_slice($parts, $i + 1);
				$fileFragment = implode(DS, $parts);
				$pluginWebroot = Plugin::path($plugin) . 'webroot' . DS;
				return $pluginWebroot . $fileFragment;
			}
		}
	}

/**
 * Sends an asset file to the client
 *
 * @param \Cake\Network\Request $request The request object to use.
 * @param \Cake\Network\Response $response The response object to use.
 * @param string $assetFile Path to the asset file in the file system
 * @param string $ext The extension of the file to determine its mime type
 * @return void
 */
	protected function _deliverAsset(Request $request, Response $response, $assetFile, $ext) {
		$compressionEnabled = $response->compress();
		if ($response->type($ext) === $ext) {
			$contentType = 'application/octet-stream';
			$agent = $request->env('HTTP_USER_AGENT');
			if (preg_match('%Opera(/| )([0-9].[0-9]{1,2})%', $agent) || preg_match('/MSIE ([0-9].[0-9]{1,2})/', $agent)) {
				$contentType = 'application/octetstream';
			}
			$response->type($contentType);
		}
		if (!$compressionEnabled) {
			$response->header('Content-Length', filesize($assetFile));
		}
		$response->cache(filemtime($assetFile));
		$response->sendHeaders();
		readfile($assetFile);
		if ($compressionEnabled) {
			ob_end_flush();
		}
	}

}