class SecuredRedirectResponse

abstract class SecuredRedirectResponse extends RedirectResponse {
  
  /**
   * Copies an existing redirect response into a safe one.
   *
   * The safe one cannot accidentally redirect to an external URL, unless
   * actively wanted (see TrustedRedirectResponse).
   *
   * @param \Symfony\Component\HttpFoundation\RedirectResponse $response
   *   The original redirect.
   *
   * @return static
   */
  public static function createFromRedirectResponse(RedirectResponse $response) {
    $safe_response = new static($response->getTargetUrl(), $response->getStatusCode(), $response->headers
      ->allPreserveCase());
    $safe_response->fromResponse($response);
    return $safe_response;
  }
  
  /**
   * Copies over the values from the given response.
   *
   * @param \Symfony\Component\HttpFoundation\RedirectResponse $response
   *   The redirect response object.
   */
  protected function fromResponse(RedirectResponse $response) {
    $this->setProtocolVersion($response->getProtocolVersion());
    if ($response->getCharset()) {
      $this->setCharset($response->getCharset());
    }
    // Cookies are separate from other headers and have to be copied over
    // directly.
    foreach ($response->headers
      ->getCookies() as $cookie) {
      $this->headers
        ->setCookie($cookie);
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function setTargetUrl($url) : static {
    if (!$this->isSafe($url)) {
      throw new \InvalidArgumentException(sprintf('It is not safe to redirect to %s', $url));
    }
    return parent::setTargetUrl($url);
  }
  
  /**
   * Returns whether the URL is considered as safe to redirect to.
   *
   * @param string $url
   *   The URL checked for safety.
   *
   * @return bool
   */
  protected abstract function isSafe($url);

}