Function NewServer

net/udprelay/server.go:382–437

NewServer constructs a [Server] listening on port. If port is zero, then port selection is left up to the host networking stack. If onlyStaticAddrPorts is true, then dynamic addr:port discovery will be disabled, and only addr:port's set via [Server.SetStaticAddrPorts] will be used. Metrics must be n

(logf logger.Logf, port uint16, onlyStaticAddrPorts bool, metrics *usermetric.Registry, knobs *controlknobs.Knobs)

// disabled, and only addr:port's set via [Server.SetStaticAddrPorts] will be
// used. Metrics must be non-nil. knobs may be nil.
func NewServer(logf logger.Logf, port uint16, onlyStaticAddrPorts bool, metrics *usermetric.Registry, knobs *controlknobs.Knobs) (s *Server, err error) {
	s = &Server{
		logf:                  logf,
		disco:                 key.NewDisco(),
		bindLifetime:          defaultBindLifetime,
		steadyStateLifetime:   defaultSteadyStateLifetime,
		closeCh:               make(chan struct{}),
		onlyStaticAddrPorts:   onlyStaticAddrPorts,
		serverEndpointByDisco: make(map[key.SortedPairOfDiscoPublic]*serverEndpoint),
		nextVNI:               minVNI,
		cloudInfo:             cloudinfo.New(logf),
		controlKnobs:          knobs,
	}
	s.discoPublic = s.disco.Public()
	s.metrics = registerMetrics(metrics)

	// TODO(creachadair): Find a way to plumb this in during initialization.
	// As-written, messages published here will not be seen by other components
	// in a running client.
	bus := eventbus.New()
	s.bus = bus
	netMon, err := netmon.New(s.bus, logf)
	if err != nil {
		return nil, err
	}
	s.netMon = netMon
	s.netChecker = &netcheck.Client{
		NetMon: netMon,
		Logf:   logger.WithPrefix(logf, "netcheck: "),
		SendPacket: func(b []byte, addrPort netip.AddrPort) (int, error) {
			if addrPort.Addr().Is4() {
				return s.uc4[0].WriteToUDPAddrPort(b, addrPort)
			} else if len(s.uc6) > 0 {
				return s.uc6[0].WriteToUDPAddrPort(b, addrPort)
			} else {
				return 0, errors.New("IPv6 socket is not bound")
			}
		},
	}

	err = s.bindSockets(port)
	if err != nil {
		return nil, err
	}
	s.startPacketReaders()

	if !s.onlyStaticAddrPorts {
		s.wg.Add(1)
		go s.addrDiscoveryLoop()
	}

	s.wg.Add(1)
	go s.endpointGCLoop()

	return s, nil
}

func (s *Server) startPacketReaders() {