think\Validate::ip PHP Method

    protected function ip($value, $rule)
    {
        if (!in_array($rule, ['ipv4', 'ipv6'])) {
            $rule = 'ipv4';
        }
        return $this->filter($value, FILTER_VALIDATE_IP, 'ipv6' == $rule ? FILTER_FLAG_IPV6 : FILTER_FLAG_IPV4);
    }