Added exteralIp

README.md

@@ -37,7 +37,7 @@ Connect on:
 In the next 3 new terminals run
 
 ```
-$ ./dht --peer /ip4/192.168.1.20/tcp/58476/p2p/12D3KooWCEsQ9vbkBCgR7gwF1xcqZiNrNkhA57EjUuho48MiypaT
+$ ./dht --peer /ip4/192.168.1.20/tcp/58476/p2p/12D3KooWCEsQ9vbkBCgR7gwF1xcqZiNrNkhA57EjUuho48MiypaT --port <port> --externalIp <your_public_ipAddress>
 ```
 
 You'll see all the nodes are connected to each other.

main.go

@@ -6,11 +6,17 @@ import (
 	"fmt"
 	"github.com/libp2p/go-libp2p"
 	"github.com/libp2p/go-libp2p/core/host"
+	"github.com/multiformats/go-multiaddr"
 	"time"
 )
 
-func CreateNode() (host.Host, error) {
-	node, err := libp2p.New()
+func CreateNode(externalIp string, port string) (host.Host, error) {
+	addressFactory, err := getAddressFactory(externalIp, port)
+	if err != nil {
+		return nil, err
+	}
+	node, err := libp2p.New(
+		libp2p.AddrsFactory(addressFactory))
 	if err != nil {
 		return nil, err
 	}
@@ -22,12 +28,39 @@ func CreateNode() (host.Host, error) {
 	return node, nil
 }
 
+func getAddressFactory(externalIP string, port string) (func([]multiaddr.Multiaddr) []multiaddr.Multiaddr, error) {
+	var (
+		externalAddr multiaddr.Multiaddr
+		err          error
+	)
+
+	// binding external IP to libp2p node
+	if len(externalIP) != 0 {
+		externalAddr, err = multiaddr.NewMultiaddr(fmt.Sprintf("/ip4/%s/tcp/%s", externalIP, port))
+		if err != nil {
+			return nil, fmt.Errorf("fail to create listen with given external IP: %v", err)
+		}
+		fmt.Printf("Binding to external IP: %v", externalAddr.String())
+	}
+	addressFactory := func(addrs []multiaddr.Multiaddr) []multiaddr.Multiaddr {
+		if externalAddr != nil {
+			return []multiaddr.Multiaddr{externalAddr}
+		}
+		return addrs
+	}
+	return addressFactory, nil
+}
+
 func main() {
 	var discoveryPeers addrList
+	var externalIp string
+	var port string
 	flag.Var(&discoveryPeers, "peer", "Peer multi address for peer discovery")
+	flag.StringVar(&externalIp, "externalIp", "", "Public IP address of user")
+	flag.StringVar(&port, "port", "", "Port of user")
 	flag.Parse()
 
-	node, err := CreateNode()
+	node, err := CreateNode(externalIp, port)
 	if err != nil {
 		panic(err)
 	}