Golang ListenUDP Examples

Example #1

File: main.go Project: expanse-project/go-expanse

func main() {
	var (
		listenAddr  = flag.String("addr", ":42787", "listen address")
		genKey      = flag.String("genkey", "", "generate a node key and quit")
		nodeKeyFile = flag.String("nodekey", "", "private key filename")
		nodeKeyHex  = flag.String("nodekeyhex", "", "private key as hex (for testing)")
		natdesc     = flag.String("nat", "none", "port mapping mechanism (any|none|upnp|pmp|extip:<IP>)")

		nodeKey *ecdsa.PrivateKey
		err     error
	)
	flag.Var(glog.GetVerbosity(), "verbosity", "log verbosity (0-9)")
	flag.Var(glog.GetVModule(), "vmodule", "log verbosity pattern")
	glog.SetToStderr(true)
	flag.Parse()

	if *genKey != "" {
		key, err := crypto.GenerateKey()
		if err != nil {
			utils.Fatalf("could not generate key: %v", err)
		}
		if err := crypto.SaveECDSA(*genKey, key); err != nil {
			utils.Fatalf("%v", err)
		}
		os.Exit(0)
	}

	natm, err := nat.Parse(*natdesc)
	if err != nil {
		utils.Fatalf("-nat: %v", err)
	}
	switch {
	case *nodeKeyFile == "" && *nodeKeyHex == "":
		utils.Fatalf("Use -nodekey or -nodekeyhex to specify a private key")
	case *nodeKeyFile != "" && *nodeKeyHex != "":
		utils.Fatalf("Options -nodekey and -nodekeyhex are mutually exclusive")
	case *nodeKeyFile != "":
		if nodeKey, err = crypto.LoadECDSA(*nodeKeyFile); err != nil {
			utils.Fatalf("-nodekey: %v", err)
		}
	case *nodeKeyHex != "":
		if nodeKey, err = crypto.HexToECDSA(*nodeKeyHex); err != nil {
			utils.Fatalf("-nodekeyhex: %v", err)
		}
	}

	if _, err := discover.ListenUDP(nodeKey, *listenAddr, natm, ""); err != nil {
		utils.Fatalf("%v", err)
	}
	select {}
}

Example #2

File: server.go Project: expanse-project/go-expanse

// Start starts running the server.
// Servers can not be re-used after stopping.
func (srv *Server) Start() (err error) {
	srv.lock.Lock()
	defer srv.lock.Unlock()
	if srv.running {
		return errors.New("server already running")
	}
	srv.running = true
	glog.V(logger.Info).Infoln("Starting Server")

	// static fields
	if srv.PrivateKey == nil {
		return fmt.Errorf("Server.PrivateKey must be set to a non-nil key")
	}
	if srv.newTransport == nil {
		srv.newTransport = newRLPX
	}
	if srv.Dialer == nil {
		srv.Dialer = &net.Dialer{Timeout: defaultDialTimeout}
	}
	srv.quit = make(chan struct{})
	srv.addpeer = make(chan *conn)
	srv.delpeer = make(chan *Peer)
	srv.posthandshake = make(chan *conn)
	srv.addstatic = make(chan *discover.Node)
	srv.peerOp = make(chan peerOpFunc)
	srv.peerOpDone = make(chan struct{})

	// node table
	if srv.Discovery {
		ntab, err := discover.ListenUDP(srv.PrivateKey, srv.ListenAddr, srv.NAT, srv.NodeDatabase)
		if err != nil {
			return err
		}
		if err := ntab.SetFallbackNodes(srv.BootstrapNodes); err != nil {
			return err
		}
		srv.ntab = ntab
	}

	dynPeers := (srv.MaxPeers + 1) / 2
	if !srv.Discovery {
		dynPeers = 0
	}
	dialer := newDialState(srv.StaticNodes, srv.ntab, dynPeers)

	// handshake
	srv.ourHandshake = &protoHandshake{Version: baseProtocolVersion, Name: srv.Name, ID: discover.PubkeyID(&srv.PrivateKey.PublicKey)}
	for _, p := range srv.Protocols {
		srv.ourHandshake.Caps = append(srv.ourHandshake.Caps, p.cap())
	}
	// listen/dial
	if srv.ListenAddr != "" {
		if err := srv.startListening(); err != nil {
			return err
		}
	}
	if srv.NoDial && srv.ListenAddr == "" {
		glog.V(logger.Warn).Infoln("I will be kind-of useless, neither dialing nor listening.")
	}

	srv.loopWG.Add(1)
	go srv.run(dialer)
	srv.running = true
	return nil
}