<?php /** * @link http://www.yiiframework.com/ * @copyright Copyright (c) 2008 Yii Software LLC * @license http://www.yiiframework.com/license/ */ namespace yii\filters; use Yii; use yii\base\ActionFilter; use yii\base\Action; /** * HttpCache implements client-side caching by utilizing the `Last-Modified` and `Etag` HTTP headers. * * It is an action filter that can be added to a controller and handles the `beforeAction` event. * * To use HttpCache, declare it in the `behaviors()` method of your controller class. * In the following example the filter will be applied to the `list`-action and * the Last-Modified header will contain the date of the last update to the user table in the database. * * ~~~ * public function behaviors() * { * return [ * [ * 'class' => 'yii\filters\HttpCache', * 'only' => ['index'], * 'lastModified' => function ($action, $params) { * $q = new \yii\db\Query(); * return $q->from('user')->max('updated_at'); * }, * // 'etagSeed' => function ($action, $params) { * // return // generate etag seed here * // } * ], * ]; * } * ~~~ * * @author Da:Sourcerer <webmaster@dasourcerer.net> * @author Qiang Xue <qiang.xue@gmail.com> * @since 2.0 */ class HttpCache extends ActionFilter { /** * @var callable a PHP callback that returns the UNIX timestamp of the last modification time. * The callback's signature should be: * * ~~~ * function ($action, $params) * ~~~ * * where `$action` is the [[Action]] object that this filter is currently handling; * `$params` takes the value of [[params]]. The callback should return a UNIX timestamp. */ public $lastModified; /** * @var callable a PHP callback that generates the Etag seed string. * The callback's signature should be: * * ~~~ * function ($action, $params) * ~~~ * * where `$action` is the [[Action]] object that this filter is currently handling; * `$params` takes the value of [[params]]. The callback should return a string serving * as the seed for generating an Etag. */ public $etagSeed; /** * @var mixed additional parameters that should be passed to the [[lastModified]] and [[etagSeed]] callbacks. */ public $params; /** * @var string the value of the `Cache-Control` HTTP header. If null, the header will not be sent. */ public $cacheControlHeader = 'public, max-age=3600'; /** * @var string the name of the cache limiter to be set when [session_cache_limiter()](http://www.php.net/manual/en/function.session-cache-limiter.php) * is called. The default value is an empty string, meaning turning off automatic sending of cache headers entirely. * You may set this property to be `public`, `private`, `private_no_expire`, and `nocache`. * Please refer to [session_cache_limiter()](http://www.php.net/manual/en/function.session-cache-limiter.php) * for detailed explanation of these values. * * If this property is `null`, then `session_cache_limiter()` will not be called. As a result, * PHP will send headers according to the `session.cache_limiter` PHP ini setting. */ public $sessionCacheLimiter = ''; /** * @var boolean a value indicating whether this filter should be enabled. */ public $enabled = true; /** * This method is invoked right before an action is to be executed (after all possible filters.) * You may override this method to do last-minute preparation for the action. * @param Action $action the action to be executed. * @return boolean whether the action should continue to be executed. */ public function beforeAction($action) { if (!$this->enabled) { return true; } $verb = Yii::$app->getRequest()->getMethod(); if ($verb !== 'GET' && $verb !== 'HEAD' || $this->lastModified === null && $this->etagSeed === null) { return true; } $lastModified = $etag = null; if ($this->lastModified !== null) { $lastModified = call_user_func($this->lastModified, $action, $this->params); } if ($this->etagSeed !== null) { $seed = call_user_func($this->etagSeed, $action, $this->params); $etag = $this->generateEtag($seed); } $this->sendCacheControlHeader(); $response = Yii::$app->getResponse(); if ($etag !== null) { $response->getHeaders()->set('Etag', $etag); } if ($this->validateCache($lastModified, $etag)) { $response->setStatusCode(304); return false; } if ($lastModified !== null) { $response->getHeaders()->set('Last-Modified', gmdate('D, d M Y H:i:s', $lastModified) . ' GMT'); } return true; } /** * Validates if the HTTP cache contains valid content. * @param integer $lastModified the calculated Last-Modified value in terms of a UNIX timestamp. * If null, the Last-Modified header will not be validated. * @param string $etag the calculated ETag value. If null, the ETag header will not be validated. * @return boolean whether the HTTP cache is still valid. */ protected function validateCache($lastModified, $etag) { if ($lastModified !== null && (!isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) || @strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) < $lastModified)) { return false; } else { return $etag === null || in_array($etag, Yii::$app->request->getEtags(), true); } } /** * Sends the cache control header to the client * @see cacheControlHeader */ protected function sendCacheControlHeader() { if ($this->sessionCacheLimiter !== null) { if ($this->sessionCacheLimiter === '' && !headers_sent() && Yii::$app->getSession()->getIsActive()) { header_remove('Expires'); header_remove('Cache-Control'); header_remove('Last-Modified'); header_remove('Pragma'); } session_cache_limiter($this->sessionCacheLimiter); } $headers = Yii::$app->getResponse()->getHeaders(); $headers->set('Pragma'); if ($this->cacheControlHeader !== null) { $headers->set('Cache-Control', $this->cacheControlHeader); } } /** * Generates an Etag from the given seed string. * @param string $seed Seed for the ETag * @return string the generated Etag */ protected function generateEtag($seed) { return '"' . base64_encode(sha1($seed, true)) . '"'; } }