nattype.go

package stun

type NatType uint

const (
	/// <summary>
	/// UDP is always blocked.
	/// </summary>
	UdpBlocked NatType = iota

	/// <summary>
	/// No NAT, public IP, no firewall.
	/// </summary>
	OpenInternet

	/// <summary>
	/// No NAT, public IP, but symmetric UDP firewall.
	/// </summary>
	SymmetricUdpFirewall

	/// <summary>
	/// A full cone NAT is one where all requests from the same internal IP address and port are
	/// mapped to the same external IP address and port. Furthermore, any external host can send
	/// a packet to the internal host, by sending a packet to the mapped external address.
	/// </summary>
	FullCone

	/// <summary>
	/// A restricted cone NAT is one where all requests from the same internal IP address and
	/// port are mapped to the same external IP address and port. Unlike a full cone NAT, an external
	/// host (with IP address X) can send a packet to the internal host only if the internal host
	/// had previously sent a packet to IP address X.
	/// </summary>
	RestrictedCone

	/// <summary>
	/// A port restricted cone NAT is like a restricted cone NAT, but the restriction
	/// includes port numbers. Specifically, an external host can send a packet, with source IP
	/// address X and source port P, to the internal host only if the internal host had previously
	/// sent a packet to IP address X and port P.
	/// </summary>
	PortRestrictedCone

	/// <summary>
	/// A symmetric NAT is one where all requests from the same internal IP address and port,
	/// to a specific destination IP address and port, are mapped to the same external IP address and
	/// port.  If the same host sends a packet with the same source address and port, but to
	/// a different destination, a different mapping is used. Furthermore, only the external host that
	/// receives a packet can send a UDP packet back to the internal host.
	/// </summary>
	Symmetric

	Unknown
)

var natTypeNames = []string{
	"UdpBlocked",
	"OpenInternet",
	"SymmetricUdpFirewall",
	"FullCone",
	"RestrictedCone",
	"PortRestrictedCone",
	"Symmetric",
	"Unknown",
}

func (natType NatType) String() string {
	if natType <= Unknown {
		return natTypeNames[natType]
	}
	return ""
}