add flag (#4622)

beacon-chain/main.go

@@ -50,6 +50,7 @@ var appFlags = []cli.Flag{
 	cmd.RelayNode,
 	cmd.P2PUDPPort,
 	cmd.P2PTCPPort,
+	cmd.P2PIP,
 	cmd.P2PHost,
 	cmd.P2PHostDNS,
 	cmd.P2PMaxPeers,

beacon-chain/node/node.go

@@ -271,6 +271,7 @@ func (b *BeaconNode) registerP2P(ctx *cli.Context) error {
 		BootstrapNodeAddr: bootnodeAddrs,
 		RelayNodeAddr:     ctx.GlobalString(cmd.RelayNode.Name),
 		DataDir:           ctx.GlobalString(cmd.DataDirFlag.Name),
+		LocalIP:           ctx.GlobalString(cmd.P2PIP.Name),
 		HostAddress:       ctx.GlobalString(cmd.P2PHost.Name),
 		HostDNS:           ctx.GlobalString(cmd.P2PHostDNS.Name),
 		PrivateKey:        ctx.GlobalString(cmd.P2PPrivKey.Name),

beacon-chain/p2p/config.go

@@ -9,6 +9,7 @@ type Config struct {
 	KademliaBootStrapAddr []string
 	Discv5BootStrapAddr   []string
 	RelayNodeAddr         string
+	LocalIP               string
 	HostAddress           string
 	HostDNS               string
 	PrivateKey            string

beacon-chain/p2p/options.go

@@ -56,6 +56,17 @@ func buildOptions(cfg *Config, ip net.IP, priKey *ecdsa.PrivateKey) []libp2p.Opt
 			return addrs
 		}))
 	}
+	if cfg.LocalIP != "" {
+		if net.ParseIP(cfg.LocalIP) == nil {
+			log.Errorf("Invalid local ip provided: %s", cfg.LocalIP)
+			return options
+		}
+		listen, err = ma.NewMultiaddr(fmt.Sprintf("/ip4/%s/tcp/%d", cfg.LocalIP, cfg.TCPPort))
+		if err != nil {
+			log.Fatalf("Failed to p2p listen: %v", err)
+		}
+		options = append(options, libp2p.ListenAddrs(listen))
+	}
 	return options
 }
 

beacon-chain/usage.go

@@ -94,6 +94,7 @@ var appHelpFlagGroups = []flagGroup{
 	{
 		Name: "p2p",
 		Flags: []cli.Flag{
+			cmd.P2PIP,
 			cmd.P2PHost,
 			cmd.P2PHostDNS,
 			cmd.P2PMaxPeers,

shared/cmd/flags.go

@@ -88,6 +88,12 @@ var (
 		Usage: "The port used by libp2p.",
 		Value: 13000,
 	}
+	// P2PIP defines the local IP to be used by libp2p.
+	P2PIP = cli.StringFlag{
+		Name:  "p2p-local-ip",
+		Usage: "The local ip address to listen for incoming data.",
+		Value: "",
+	}
 	// P2PHost defines the host IP to be used by libp2p.
 	P2PHost = cli.StringFlag{
 		Name:  "p2p-host-ip",