nattype.go

package network

// NATDeviceType indicates the type of the NAT device.
type NATDeviceType int

const (
	// NATDeviceTypeUnknown indicates that the type of the NAT device is unknown.
	NATDeviceTypeUnknown NATDeviceType = iota

	// NATDeviceTypeCone indicates that the NAT device is a Cone NAT.
	// A Cone NAT is a NAT where all outgoing connections from the same source IP address and port are mapped by the NAT device
	// to the same IP address and port irrespective of the destination address.
	// With regards to RFC 3489, this could be either a Full Cone NAT, a Restricted Cone NAT or a
	// Port Restricted Cone NAT. However, we do NOT differentiate between them here and simply classify all such NATs as a Cone NAT.
	// NAT traversal with hole punching is possible with a Cone NAT ONLY if the remote peer is ALSO behind a Cone NAT.
	// If the remote peer is behind a Symmetric NAT, hole punching will fail.
	NATDeviceTypeCone

	// NATDeviceTypeSymmetric indicates that the NAT device is a Symmetric NAT.
	// A Symmetric NAT maps outgoing connections with different destination addresses to different IP addresses and ports,
	// even if they originate from the same source IP address and port.
	// NAT traversal with hole-punching is currently NOT possible in libp2p with Symmetric NATs irrespective of the remote peer's NAT type.
	NATDeviceTypeSymmetric
)

func (r NATDeviceType) String() string {
	switch r {
	case 0:
		return "Unknown"
	case 1:
		return "Cone"
	case 2:
		return "Symmetric"
	default:
		return "unrecognized"
	}
}

// NATTransportProtocol is the transport protocol for which the NAT Device Type has been determined.
type NATTransportProtocol int

const (
	// NATTransportUDP means that the NAT Device Type has been determined for the UDP Protocol.
	NATTransportUDP NATTransportProtocol = iota
	// NATTransportTCP means that the NAT Device Type has been determined for the TCP Protocol.
	NATTransportTCP
)

func (n NATTransportProtocol) String() string {
	switch n {
	case 0:
		return "UDP"
	case 1:
		return "TCP"
	default:
		return "unrecognized"
	}
}