Use net.JoinHostPort() instead of hand-joining

Hand-joining breaks IPv6 literal addresses (which must be enclosed in
brackets).

identitychain/identitychain.go

@@ -124,7 +124,8 @@ func (IDC *IdentityChain) StartServer() {
 }
 
 func (IDC *IdentityChain) listenOnPort() {
-	listen, err := net.Listen("tcp4", ":"+IDC.Peer.Port)
+	addr := net.JoinHostPort("", IDC.Peer.Port)
+	listen, err := net.Listen("tcp4", addr)
 	if err != nil {
 		IDC.log.Crit("Socket listen port failed")
 		os.Exit(1)

node/node.go

@@ -82,14 +82,15 @@ func (node *Node) StartServer(port string) {
 }
 
 func (node *Node) listenOnPort(port string) {
-	listen, err := net.Listen("tcp4", ":"+port)
+	addr := net.JoinHostPort("", port)
+	listen, err := net.Listen("tcp4", addr)
 	defer func(listen net.Listener) {
 		if listen != nil {
 			listen.Close()
 		}
 	}(listen)
 	if err != nil {
-		node.log.Error("Socket listen port failed", "port", port, "err", err)
+		node.log.Error("Socket listen port failed", "addr", addr, "err", err)
 		return
 	}
 	for {

p2p/peer.go

@@ -100,7 +100,7 @@ func ConstructP2pMessage(msgType byte, content []byte) []byte {
 // TODO(minhdoan, rj): need to check if a peer is reachable or not.
 func sendWithSocketClient(ip, port string, message []byte) (res string) {
 	//log.Printf("Sending message to ip %s and port %s\n", ip, port)
-	addr := strings.Join([]string{ip, port}, ":")
+	addr := net.JoinHostPort(ip, port)
 	conn, err := net.Dial("tcp", addr)
 
 	if err != nil {
@@ -127,7 +127,7 @@ func send(ip, port string, message []byte) (returnMessage string) {
 
 func DialWithSocketClient(ip, port string) (conn net.Conn, err error) {
 	//log.Printf("Sending message to ip %s and port %s\n", ip, port)
-	addr := strings.Join([]string{ip, port}, ":")
+	addr := net.JoinHostPort(ip, port)
 	conn, err = net.Dial("tcp", addr)
 	return
 }