public function getClientIp(): string {
        $s = $this->server();
        if (array_key_exists('HTTP_CLIENTIP', $s)) {
            if (!empty($s['HTTP_CLIENTIP'])) {
                return $s['HTTP_CLIENTIP'];
            }
        }
        if (array_key_exists('HTTP_X_FORWARDED_FOR', $s) && !empty($s['HTTP_X_FORWARDED_FOR'])) {
            $addresses = explode(',', $s['HTTP_X_FORWARDED_FOR']);
            while (count($addresses)) {
                $ip = @trim(array_shift($addresses));
                if ($ip === '') {
                    continue;
                }
                if (!self::isLanIp($ip)) {
                    return $ip;
                }
            }
        }
        return $s['REMOTE_ADDR'];
    }