dfm-8.x-1.16/src/EventSubscriber/DfmSubscriber.php

<?php

namespace Drupal\dfm\EventSubscriber;

use Drupal\dfm\Dfm;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpKernel\Event\RequestEvent;
use Symfony\Component\HttpKernel\KernelEvents;

/**
 * Defines a custom event subscriber.
 */
class DfmSubscriber implements EventSubscriberInterface {

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() {
    $events[KernelEvents::REQUEST][] = ['requestInit'];
    return $events;
  }

  /**
   * Performs operations before the request is processed.
   */
  public function requestInit(RequestEvent $event) {
    // Allow image derivatives temporarily.
    $request = $event->getRequest();
    $itok = $request->query->get('dfm_itok');
    if ($itok && $request->query->get('file')) {
      $path = $request->getPathInfo();
      if (!\Drupal::config('image.settings')->get('allow_insecure_derivatives')) {
        $pos = strpos($path, '/styles/');
        if ($pos) {
          $args = explode('/', substr($path, $pos + 8));
          if ($itok === Dfm::itok($args[0])) {
            $GLOBALS['config']['image.settings']['allow_insecure_derivatives'] = TRUE;
            // Reset the config to rebuild overrides.
            \Drupal::configFactory()->reset('image.settings');
          }
        }
      }
    }
  }

}