Esi.php

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace Symfony\Component\HttpKernel\HttpCache;

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\HttpKernelInterface;

/**
 * Esi implements the ESI capabilities to Request and Response instances.
 *
 * For more information, read the following W3C notes:
 *
 *  * ESI Language Specification 1.0 (http://www.w3.org/TR/esi-lang)
 *
 *  * Edge Architecture Specification (http://www.w3.org/TR/edge-arch)
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class Esi {
  private $contentTypes;

  /**
   * Constructor.
   *
   * @param array $contentTypes An array of content-type that should be parsed for ESI information.
   *                           (default: text/html, text/xml, application/xhtml+xml, and application/xml)
   */
  public function __construct(array $contentTypes = array(
    'text/html',
    'text/xml',
    'application/xhtml+xml',
    'application/xml',
  )) {
    $this->contentTypes = $contentTypes;
  }

  /**
   * Returns a new cache strategy instance.
   *
   * @return EsiResponseCacheStrategyInterface A EsiResponseCacheStrategyInterface instance
   */
  public function createCacheStrategy() {
    return new EsiResponseCacheStrategy();
  }

  /**
   * Checks that at least one surrogate has ESI/1.0 capability.
   *
   * @param Request $request A Request instance
   *
   * @return Boolean true if one surrogate has ESI/1.0 capability, false otherwise
   */
  public function hasSurrogateEsiCapability(Request $request) {
    if (null === ($value = $request->headers
      ->get('Surrogate-Capability'))) {
      return false;
    }
    return false !== strpos($value, 'ESI/1.0');
  }

  /**
   * Adds ESI/1.0 capability to the given Request.
   *
   * @param Request $request A Request instance
   */
  public function addSurrogateEsiCapability(Request $request) {
    $current = $request->headers
      ->get('Surrogate-Capability');
    $new = 'symfony2="ESI/1.0"';
    $request->headers
      ->set('Surrogate-Capability', $current ? $current . ', ' . $new : $new);
  }

  /**
   * Adds HTTP headers to specify that the Response needs to be parsed for ESI.
   *
   * This method only adds an ESI HTTP header if the Response has some ESI tags.
   *
   * @param Response $response A Response instance
   */
  public function addSurrogateControl(Response $response) {
    if (false !== strpos($response
      ->getContent(), '<esi:include')) {
      $response->headers
        ->set('Surrogate-Control', 'content="ESI/1.0"');
    }
  }

  /**
   * Checks that the Response needs to be parsed for ESI tags.
   *
   * @param Response $response A Response instance
   *
   * @return Boolean true if the Response needs to be parsed, false otherwise
   */
  public function needsEsiParsing(Response $response) {
    if (!($control = $response->headers
      ->get('Surrogate-Control'))) {
      return false;
    }
    return (bool) preg_match('#content="[^"]*ESI/1.0[^"]*"#', $control);
  }

  /**
   * Renders an ESI tag.
   *
   * @param string  $uri          A URI
   * @param string  $alt          An alternate URI
   * @param Boolean $ignoreErrors Whether to ignore errors or not
   * @param string  $comment      A comment to add as an esi:include tag
   *
   * @return string
   */
  public function renderIncludeTag($uri, $alt = null, $ignoreErrors = true, $comment = '') {
    $html = sprintf('<esi:include src="%s"%s%s />', $uri, $ignoreErrors ? ' onerror="continue"' : '', $alt ? sprintf(' alt="%s"', $alt) : '');
    if (!empty($comment)) {
      return sprintf("<esi:comment text=\"%s\" />\n%s", $comment, $html);
    }
    return $html;
  }

  /**
   * Replaces a Response ESI tags with the included resource content.
   *
   * @param Request  $request  A Request instance
   * @param Response $response A Response instance
   *
   * @return Response
   */
  public function process(Request $request, Response $response) {
    $this->request = $request;
    $type = $response->headers
      ->get('Content-Type');
    if (empty($type)) {
      $type = 'text/html';
    }
    $parts = explode(';', $type);
    if (!in_array($parts[0], $this->contentTypes)) {
      return $response;
    }

    // we don't use a proper XML parser here as we can have ESI tags in a plain text response
    $content = $response
      ->getContent();
    $content = str_replace(array(
      '<?',
      '<%',
    ), array(
      '<?php echo "<?"; ?>',
      '<?php echo "<%"; ?>',
    ), $content);
    $content = preg_replace_callback('#<esi\\:include\\s+(.*?)\\s*(?:/|</esi\\:include)>#', array(
      $this,
      'handleEsiIncludeTag',
    ), $content);
    $content = preg_replace('#<esi\\:comment[^>]*(?:/|</esi\\:comment)>#', '', $content);
    $content = preg_replace('#<esi\\:remove>.*?</esi\\:remove>#', '', $content);
    $response
      ->setContent($content);
    $response->headers
      ->set('X-Body-Eval', 'ESI');

    // remove ESI/1.0 from the Surrogate-Control header
    if ($response->headers
      ->has('Surrogate-Control')) {
      $value = $response->headers
        ->get('Surrogate-Control');
      if ('content="ESI/1.0"' == $value) {
        $response->headers
          ->remove('Surrogate-Control');
      }
      elseif (preg_match('#,\\s*content="ESI/1.0"#', $value)) {
        $response->headers
          ->set('Surrogate-Control', preg_replace('#,\\s*content="ESI/1.0"#', '', $value));
      }
      elseif (preg_match('#content="ESI/1.0",\\s*#', $value)) {
        $response->headers
          ->set('Surrogate-Control', preg_replace('#content="ESI/1.0",\\s*#', '', $value));
      }
    }
  }

  /**
   * Handles an ESI from the cache.
   *
   * @param HttpCache $cache        An HttpCache instance
   * @param string    $uri          The main URI
   * @param string    $alt          An alternative URI
   * @param Boolean   $ignoreErrors Whether to ignore errors or not
   *
   * @return string
   *
   * @throws \RuntimeException
   * @throws \Exception
   */
  public function handle(HttpCache $cache, $uri, $alt, $ignoreErrors) {
    $subRequest = Request::create($uri, 'get', array(), $cache
      ->getRequest()->cookies
      ->all(), array(), $cache
      ->getRequest()->server
      ->all());
    try {
      $response = $cache
        ->handle($subRequest, HttpKernelInterface::SUB_REQUEST, true);
      if (!$response
        ->isSuccessful()) {
        throw new \RuntimeException(sprintf('Error when rendering "%s" (Status code is %s).', $subRequest
          ->getUri(), $response
          ->getStatusCode()));
      }
      return $response
        ->getContent();
    } catch (\Exception $e) {
      if ($alt) {
        return $this
          ->handle($cache, $alt, '', $ignoreErrors);
      }
      if (!$ignoreErrors) {
        throw $e;
      }
    }
  }

  /**
   * Handles an ESI include tag (called internally).
   *
   * @param array $attributes An array containing the attributes.
   *
   * @return string The response content for the include.
   *
   * @throws \RuntimeException
   */
  private function handleEsiIncludeTag($attributes) {
    $options = array();
    preg_match_all('/(src|onerror|alt)="([^"]*?)"/', $attributes[1], $matches, PREG_SET_ORDER);
    foreach ($matches as $set) {
      $options[$set[1]] = $set[2];
    }
    if (!isset($options['src'])) {
      throw new \RuntimeException('Unable to process an ESI tag without a "src" attribute.');
    }
    return sprintf('<?php echo $this->esi->handle($this, \'%s\', \'%s\', %s) ?>' . "\n", $options['src'], isset($options['alt']) ? $options['alt'] : null, isset($options['onerror']) && 'continue' == $options['onerror'] ? 'true' : 'false');
  }

}