system/HTTP/Request.php
public function isValidIP(string $ip = null, string $which = null): bool
	{
		switch (strtolower($which))
		{
			case 'ipv4':
				$which = FILTER_FLAG_IPV4;
				break;
			case 'ipv6':
				$which = FILTER_FLAG_IPV6;
				break;
			default:
				$which = null;
				break;
		}

		return (bool) filter_var($ip, FILTER_VALIDATE_IP, $which);
	}
public function isValidIP(string $ip = null, string $which = null): bool
	{
		switch (strtolower($which))
		{
			case 'ipv4':
				$which = FILTER_FLAG_IPV4;
				break;
			case 'ipv6':
				$which = FILTER_FLAG_IPV6;
				break;
			default:
				$which = null;
				break;
		}

		return (bool) filter_var($ip, FILTER_VALIDATE_IP, $which);
	}
Validate an IP address

@param string $ip    IP Address
@param string $which IP protocol: 'ipv4' or 'ipv6'

@return boolean