Chris@0: <?php
Chris@0: 
Chris@0: /*
Chris@0:  * This file is part of the Symfony package.
Chris@0:  *
Chris@0:  * (c) Fabien Potencier <fabien@symfony.com>
Chris@0:  *
Chris@0:  * For the full copyright and license information, please view the LICENSE
Chris@0:  * file that was distributed with this source code.
Chris@0:  */
Chris@0: 
Chris@0: namespace Symfony\Component\HttpKernel\HttpCache;
Chris@0: 
Chris@0: use Symfony\Component\HttpFoundation\Response;
Chris@0: 
Chris@0: /**
Chris@0:  * ResponseCacheStrategy knows how to compute the Response cache HTTP header
Chris@0:  * based on the different response cache headers.
Chris@0:  *
Chris@0:  * This implementation changes the master response TTL to the smallest TTL received
Chris@0:  * or force validation if one of the surrogates has validation cache strategy.
Chris@0:  *
Chris@0:  * @author Fabien Potencier <fabien@symfony.com>
Chris@0:  */
Chris@0: class ResponseCacheStrategy implements ResponseCacheStrategyInterface
Chris@0: {
Chris@18:     /**
Chris@18:      * Cache-Control headers that are sent to the final response if they appear in ANY of the responses.
Chris@18:      */
Chris@18:     private static $overrideDirectives = ['private', 'no-cache', 'no-store', 'no-transform', 'must-revalidate', 'proxy-revalidate'];
Chris@18: 
Chris@18:     /**
Chris@18:      * Cache-Control headers that are sent to the final response if they appear in ALL of the responses.
Chris@18:      */
Chris@18:     private static $inheritDirectives = ['public', 'immutable'];
Chris@18: 
Chris@0:     private $embeddedResponses = 0;
Chris@0:     private $isNotCacheableResponseEmbedded = false;
Chris@18:     private $age = 0;
Chris@18:     private $flagDirectives = [
Chris@18:         'no-cache' => null,
Chris@18:         'no-store' => null,
Chris@18:         'no-transform' => null,
Chris@18:         'must-revalidate' => null,
Chris@18:         'proxy-revalidate' => null,
Chris@18:         'public' => null,
Chris@18:         'private' => null,
Chris@18:         'immutable' => null,
Chris@18:     ];
Chris@18:     private $ageDirectives = [
Chris@18:         'max-age' => null,
Chris@18:         's-maxage' => null,
Chris@18:         'expires' => null,
Chris@18:     ];
Chris@0: 
Chris@0:     /**
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function add(Response $response)
Chris@0:     {
Chris@18:         ++$this->embeddedResponses;
Chris@0: 
Chris@18:         foreach (self::$overrideDirectives as $directive) {
Chris@18:             if ($response->headers->hasCacheControlDirective($directive)) {
Chris@18:                 $this->flagDirectives[$directive] = true;
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@18:         foreach (self::$inheritDirectives as $directive) {
Chris@18:             if (false !== $this->flagDirectives[$directive]) {
Chris@18:                 $this->flagDirectives[$directive] = $response->headers->hasCacheControlDirective($directive);
Chris@18:             }
Chris@18:         }
Chris@18: 
Chris@18:         $age = $response->getAge();
Chris@18:         $this->age = max($this->age, $age);
Chris@18: 
Chris@18:         if ($this->willMakeFinalResponseUncacheable($response)) {
Chris@18:             $this->isNotCacheableResponseEmbedded = true;
Chris@18: 
Chris@18:             return;
Chris@18:         }
Chris@18: 
Chris@18:         $this->storeRelativeAgeDirective('max-age', $response->headers->getCacheControlDirective('max-age'), $age);
Chris@18:         $this->storeRelativeAgeDirective('s-maxage', $response->headers->getCacheControlDirective('s-maxage') ?: $response->headers->getCacheControlDirective('max-age'), $age);
Chris@18: 
Chris@18:         $expires = $response->getExpires();
Chris@18:         $expires = null !== $expires ? $expires->format('U') - $response->getDate()->format('U') : null;
Chris@18:         $this->storeRelativeAgeDirective('expires', $expires >= 0 ? $expires : null, 0);
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function update(Response $response)
Chris@0:     {
Chris@0:         // if we have no embedded Response, do nothing
Chris@0:         if (0 === $this->embeddedResponses) {
Chris@0:             return;
Chris@0:         }
Chris@0: 
Chris@18:         // Remove validation related headers of the master response,
Chris@18:         // because some of the response content comes from at least
Chris@18:         // one embedded response (which likely has a different caching strategy).
Chris@18:         $response->setEtag(null);
Chris@18:         $response->setLastModified(null);
Chris@12: 
Chris@18:         $this->add($response);
Chris@0: 
Chris@18:         $response->headers->set('Age', $this->age);
Chris@18: 
Chris@18:         if ($this->isNotCacheableResponseEmbedded) {
Chris@18:             $response->setExpires($response->getDate());
Chris@18: 
Chris@18:             if ($this->flagDirectives['no-store']) {
Chris@18:                 $response->headers->set('Cache-Control', 'no-cache, no-store, must-revalidate');
Chris@18:             } else {
Chris@18:                 $response->headers->set('Cache-Control', 'no-cache, must-revalidate');
Chris@18:             }
Chris@0: 
Chris@0:             return;
Chris@0:         }
Chris@0: 
Chris@18:         $flags = array_filter($this->flagDirectives);
Chris@0: 
Chris@18:         if (isset($flags['must-revalidate'])) {
Chris@18:             $flags['no-cache'] = true;
Chris@0:         }
Chris@18: 
Chris@18:         $response->headers->set('Cache-Control', implode(', ', array_keys($flags)));
Chris@18: 
Chris@18:         $maxAge = null;
Chris@18:         $sMaxage = null;
Chris@18: 
Chris@18:         if (\is_numeric($this->ageDirectives['max-age'])) {
Chris@18:             $maxAge = $this->ageDirectives['max-age'] + $this->age;
Chris@18:             $response->headers->addCacheControlDirective('max-age', $maxAge);
Chris@18:         }
Chris@18: 
Chris@18:         if (\is_numeric($this->ageDirectives['s-maxage'])) {
Chris@18:             $sMaxage = $this->ageDirectives['s-maxage'] + $this->age;
Chris@18: 
Chris@18:             if ($maxAge !== $sMaxage) {
Chris@18:                 $response->headers->addCacheControlDirective('s-maxage', $sMaxage);
Chris@18:             }
Chris@18:         }
Chris@18: 
Chris@18:         if (\is_numeric($this->ageDirectives['expires'])) {
Chris@18:             $date = clone $response->getDate();
Chris@18:             $date->modify('+'.($this->ageDirectives['expires'] + $this->age).' seconds');
Chris@18:             $response->setExpires($date);
Chris@18:         }
Chris@18:     }
Chris@18: 
Chris@18:     /**
Chris@18:      * RFC2616, Section 13.4.
Chris@18:      *
Chris@18:      * @see https://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.4
Chris@18:      *
Chris@18:      * @return bool
Chris@18:      */
Chris@18:     private function willMakeFinalResponseUncacheable(Response $response)
Chris@18:     {
Chris@18:         // RFC2616: A response received with a status code of 200, 203, 300, 301 or 410
Chris@18:         // MAY be stored by a cache […] unless a cache-control directive prohibits caching.
Chris@18:         if ($response->headers->hasCacheControlDirective('no-cache')
Chris@18:             || $response->headers->getCacheControlDirective('no-store')
Chris@18:         ) {
Chris@18:             return true;
Chris@18:         }
Chris@18: 
Chris@18:         // Last-Modified and Etag headers cannot be merged, they render the response uncacheable
Chris@18:         // by default (except if the response also has max-age etc.).
Chris@18:         if (\in_array($response->getStatusCode(), [200, 203, 300, 301, 410])
Chris@18:             && null === $response->getLastModified()
Chris@18:             && null === $response->getEtag()
Chris@18:         ) {
Chris@18:             return false;
Chris@18:         }
Chris@18: 
Chris@18:         // RFC2616: A response received with any other status code (e.g. status codes 302 and 307)
Chris@18:         // MUST NOT be returned in a reply to a subsequent request unless there are
Chris@18:         // cache-control directives or another header(s) that explicitly allow it.
Chris@18:         $cacheControl = ['max-age', 's-maxage', 'must-revalidate', 'proxy-revalidate', 'public', 'private'];
Chris@18:         foreach ($cacheControl as $key) {
Chris@18:             if ($response->headers->hasCacheControlDirective($key)) {
Chris@18:                 return false;
Chris@18:             }
Chris@18:         }
Chris@18: 
Chris@18:         if ($response->headers->has('Expires')) {
Chris@18:             return false;
Chris@18:         }
Chris@18: 
Chris@18:         return true;
Chris@18:     }
Chris@18: 
Chris@18:     /**
Chris@18:      * Store lowest max-age/s-maxage/expires for the final response.
Chris@18:      *
Chris@18:      * The response might have been stored in cache a while ago. To keep things comparable,
Chris@18:      * we have to subtract the age so that the value is normalized for an age of 0.
Chris@18:      *
Chris@18:      * If the value is lower than the currently stored value, we update the value, to keep a rolling
Chris@18:      * minimal value of each instruction. If the value is NULL, the directive will not be set on the final response.
Chris@18:      *
Chris@18:      * @param string   $directive
Chris@18:      * @param int|null $value
Chris@18:      * @param int      $age
Chris@18:      */
Chris@18:     private function storeRelativeAgeDirective($directive, $value, $age)
Chris@18:     {
Chris@18:         if (null === $value) {
Chris@18:             $this->ageDirectives[$directive] = false;
Chris@18:         }
Chris@18: 
Chris@18:         if (false !== $this->ageDirectives[$directive]) {
Chris@18:             $value -= $age;
Chris@18:             $this->ageDirectives[$directive] = null !== $this->ageDirectives[$directive] ? min($this->ageDirectives[$directive], $value) : $value;
Chris@18:         }
Chris@0:     }
Chris@0: }