private function getUrlFromSubmitFields()
    {
        $requestKey = $this->requestKey;
        $url = isset($_GET[$requestKey]) && is_scalar($_GET[$requestKey]) ? $_GET[$requestKey] : (isset($_POST[$requestKey]) && is_scalar($_POST[$requestKey]) ? $_POST[$requestKey] : false);
        $url = str_replace(chr(0), '', $url); // strip nul byte
        $url = preg_replace('/\s+/', '', $url); // strip whitespace
        return isset($_GET[$requestKey]) && is_scalar($_GET[$requestKey]) ? $this->urlDecode($url) : $url;
    }