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<?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\Action;
use yii\base\ActionFilter;
/**
* 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 `index` action and
* the Last-Modified header will contain the date of the last update to the user table in the database.
*
* ```php
* 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, $params) {
* // return // generate ETag seed here
* // }
* ],
* ];
* }
* ```
*
* @author Da:Sourcerer <webmaster@dasourcerer.net>
* @author Qiang Xue <qiang.xue@gmail.com>
* @since 2.0
*/
class HttpCache extends ActionFilter
{
/**
* @var callable a PHP callback that returns the UNIX timestamp of the last modification time.
* The callback's signature should be:
*
* ```php
* function ($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.
*
* @see http://tools.ietf.org/html/rfc7232#section-2.2
*/
public $lastModified;
/**
* @var callable a PHP callback that generates the ETag seed string.
* The callback's signature should be:
*
* ```php
* function ($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 bool whether to generate weak ETags.
*
* Weak ETags should be used if the content should be considered semantically equivalent, but not byte-equal.
*
* @since 2.0.8
* @see http://tools.ietf.org/html/rfc7232#section-2.3
*/
public $weakEtag = false;
/**
* @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.
* @see http://tools.ietf.org/html/rfc2616#section-14.9
*/
public $cacheControlHeader = 'public, max-age=3600';
/**
* @var string the name of the cache limiter to be set when [session_cache_limiter()](https://secure.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()](https://secure.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 bool 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 $action the action to be executed.
* @return bool whether the action should continue to be executed.
*/
public function beforeAction($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, $this->params);
if ($seed !== null) {
$etag = $this->generateEtag($seed);
}
}
$this->sendCacheControlHeader();
$response = Yii::$app->getResponse();
if ($etag !== null) {
$response->getHeaders()->set('Etag', $etag);
}
$cacheValid = $this->validateCache($lastModified, $etag);
// https://tools.ietf.org/html/rfc7232#section-4.1
if ($lastModified !== null && (!$cacheValid || ($cacheValid && $etag === null))) {
$response->getHeaders()->set('Last-Modified', gmdate('D, d M Y H:i:s', $lastModified) . ' GMT');
}
if ($cacheValid) {
$response->setStatusCode(304);
return false;
}
return true;
}
/**
* Validates if the HTTP cache contains valid content.
* If both Last-Modified and ETag are null, returns false.
* @param int $lastModified the calculated Last-Modified value in terms of a UNIX timestamp.
* If null, the Last-Modified header will not be validated.
* @param string $etag the calculated ETag value. If null, the ETag header will not be validated.
* @return bool whether the HTTP cache is still valid.
*/
protected function validateCache($lastModified, $etag)
{
if (Yii::$app->request->headers->has('If-None-Match')) {
// HTTP_IF_NONE_MATCH takes precedence over HTTP_IF_MODIFIED_SINCE
// http://tools.ietf.org/html/rfc7232#section-3.3
return $etag !== null && in_array($etag, Yii::$app->request->getETags(), true);
} elseif (Yii::$app->request->headers->has('If-Modified-Since')) {
return $lastModified !== null && @strtotime(Yii::$app->request->headers->get('If-Modified-Since')) >= $lastModified;
}
return false;
}
/**
* Sends the cache control header to the client.
* @see cacheControlHeader
*/
protected function sendCacheControlHeader()
{
if ($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');
}
Yii::$app->getSession()->setCacheLimiter($this->sessionCacheLimiter);
}
$headers = Yii::$app->getResponse()->getHeaders();
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)
{
$etag = '"' . rtrim(base64_encode(sha1($seed, true)), '=') . '"';
return $this->weakEtag ? 'W/' . $etag : $etag;
}
}
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