disco

type AllocateUDPRelayEndpointRequest struct {
	// ClientDisco are the Disco public keys of the clients that should be
	// permitted to handshake with the endpoint.
	ClientDisco [2]key.DiscoPublic
	// Generation represents the allocation request generation. The server must
	// echo it back in the [AllocateUDPRelayEndpointResponse] to enable request
	// and response alignment client-side.
	Generation uint32
}

type AllocateUDPRelayEndpointResponse struct {
	// Generation represents the allocation request generation. The server must
	// echo back the [AllocateUDPRelayEndpointRequest.Generation] here to enable
	// request and response alignment client-side.
	Generation uint32
	UDPRelayEndpoint
}

type BindUDPRelayEndpoint struct {
	BindUDPRelayEndpointCommon
}

type BindUDPRelayEndpointAnswer struct {
	BindUDPRelayEndpointCommon
}

type BindUDPRelayEndpointChallenge struct {
	BindUDPRelayEndpointCommon
}

type BindUDPRelayEndpointCommon struct {
	// VNI is the Geneve header Virtual Network Identifier field value, which
	// must match this disco-sealed value upon reception. If they are
	// non-matching it indicates the cleartext Geneve header was tampered with
	// and/or mangled.
	VNI uint32
	// Generation represents the handshake generation. Clients must set a new,
	// nonzero value at the start of every handshake.
	Generation uint32
	// RemoteKey is the disco key of the remote peer participating over this
	// relay endpoint.
	RemoteKey key.DiscoPublic
	// Challenge is set by the server in a [BindUDPRelayEndpointChallenge]
	// message, and expected to be echoed back by the client in a
	// [BindUDPRelayEndpointAnswer] message. Its value is irrelevant in a
	// [BindUDPRelayEndpoint] message, where it simply serves a padding purpose
	// ensuring all handshake messages are equal in size.
	Challenge [BindUDPRelayChallengeLen]byte
}

type BindUDPRelayHandshakeState int

type CallMeMaybe struct {
	// MyNumber is what the peer believes its endpoints are.
	//
	// Prior to Tailscale 1.4, the endpoints were exchanged purely
	// between nodes and the control server.
	//
	// Starting with Tailscale 1.4, clients advertise their endpoints.
	// Older clients won't use this, but newer clients should
	// use any endpoints in here that aren't included from control.
	//
	// Control might have sent stale endpoints if the client was idle
	// before contacting us. In that case, the client likely did a STUN
	// request immediately before sending the CallMeMaybe to recreate
	// their NAT port mapping, and that new good endpoint is included
	// in this field, but might not yet be in control's endpoints.
	// (And in the future, control will stop distributing endpoints
	// when clients are suitably new.)
	MyNumber []netip.AddrPort
}

type CallMeMaybeVia struct {
	UDPRelayEndpoint
}

type Message interface {
	// AppendMarshal appends the message's marshaled representation.
	// TODO(jwhited): consider using a signature matching encoding.BinaryAppender
	AppendMarshal([]byte) []byte
}

type MessageType byte

type Ping struct {
	// TxID is a random client-generated per-ping transaction ID.
	TxID [12]byte

	// NodeKey is allegedly the ping sender's wireguard public key.
	// Old clients (~1.16.0 and earlier) don't send this field.
	// It shouldn't be trusted by itself, but can be combined with
	// netmap data to reduce the discokey:nodekey relation from 1:N to
	// 1:1.
	NodeKey key.NodePublic

	// Padding is the number of 0 bytes at the end of the
	// message. (It's used to probe path MTU.)
	Padding int
}

type Pong struct {
	TxID [12]byte
	Src  netip.AddrPort // 18 bytes (16+2) on the wire; v4-mapped ipv6 for IPv4
}

type UDPRelayEndpoint struct {
	// ServerDisco is [tailscale.com/net/udprelay/endpoint.ServerEndpoint.ServerDisco]
	ServerDisco key.DiscoPublic
	// ClientDisco is [tailscale.com/net/udprelay/endpoint.ServerEndpoint.ClientDisco]
	ClientDisco [2]key.DiscoPublic
	// LamportID is [tailscale.com/net/udprelay/endpoint.ServerEndpoint.LamportID]
	LamportID uint64
	// VNI is [tailscale.com/net/udprelay/endpoint.ServerEndpoint.VNI]
	VNI uint32
	// BindLifetime is [tailscale.com/net/udprelay/endpoint.ServerEndpoint.BindLifetime]
	BindLifetime time.Duration
	// SteadyStateLifetime is [tailscale.com/net/udprelay/endpoint.ServerEndpoint.SteadyStateLifetime]
	SteadyStateLifetime time.Duration
	// AddrPorts is [tailscale.com/net/udprelay/endpoint.ServerEndpoint.AddrPorts]
	AddrPorts []netip.AddrPort
}