bugfix: Listen always return err. test it

convert.go

@@ -154,6 +154,7 @@ func DialArgs(m ma.Multiaddr) (string, string, error) {
 	if parts[2] == "udp" && len(parts) > 4 && parts[4] == "utp" {
 		network = parts[4]
 	}
+
 	var host string
 	switch parts[0] {
 	case "ip4":

net.go

@@ -226,14 +226,11 @@ func Listen(laddr ma.Multiaddr) (Listener, error) {
 	switch lnet {
 	case "utp":
 		nl, err = utp.Listen(lnet, lnaddr)
-		if err != nil {
-			return nil, err
-		}
-	case "tcp":
+	default:
 		nl, err = net.Listen(lnet, lnaddr)
-		if err != nil {
-			return nil, err
-		}
+	}
+	if err != nil {
+		return nil, err
 	}
 
 	return &maListener{

net_test.go

@@ -138,6 +138,36 @@ func TestListen(t *testing.T) {
 	wg.Wait()
 }
 
+func TestListenAddrs(t *testing.T) {
+
+	test := func(addr string, succeed bool) {
+
+		maddr := newMultiaddr(t, addr)
+		l, err := Listen(maddr)
+		if !succeed {
+			if err == nil {
+				t.Fatal("succeeded in listening", addr)
+			}
+			return
+		}
+		if succeed && err != nil {
+			t.Fatal("failed to listen", addr, err)
+		}
+		if l == nil {
+			t.Fatal("failed to listen", addr, succeed, err)
+		}
+
+		if err = l.Close(); err != nil {
+			t.Fatal("failed to close listener", addr, err)
+		}
+	}
+
+	test("/ip4/127.0.0.1/tcp/4324", true)
+	test("/ip4/127.0.0.1/udp/4325", false)
+	test("/ip4/127.0.0.1/udp/4326/udt", false)
+	test("/ip4/127.0.0.1/udp/4326/utp", true)
+}
+
 func TestListenAndDial(t *testing.T) {
 
 	maddr := newMultiaddr(t, "/ip4/127.0.0.1/tcp/4323")