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($url) {
        if (!$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);

}