feat: Change default listen address to 0.0.0.0

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -18,6 +18,7 @@ Additional documentation and release notes are available at [Multiplayer Documen
 ### Changed
 
 - Changed 3rd-party `XXHash` (32 & 64) implementation with an in-house reimplementation (#2310)
+- The default listen address of `UnityTransport` is now 0.0.0.0. (#2307)
 - When `NetworkConfig.EnsureNetworkVariableLengthSafety` is disabled `NetworkVariable` fields do not write the additional `ushort` size value (_which helps to reduce the total synchronization message size_), but when enabled it still writes the additional `ushort` value. (#2298)
 - Optimized bandwidth usage by encoding most integer fields using variable-length encoding. (#2276)
 

com.unity.netcode.gameobjects/Runtime/Transports/UTP/UnityTransport.cs

@@ -147,7 +147,7 @@ private enum State
         // frame at 60 FPS. This will be a large over-estimation in any realistic scenario.
         private const int k_MaxReliableThroughput = (NetworkParameterConstants.MTU * 32 * 60) / 1000; // bytes per millisecond
 
-        private static ConnectionAddressData s_DefaultConnectionAddressData = new ConnectionAddressData { Address = "127.0.0.1", Port = 7777, ServerListenAddress = string.Empty };
+        private static ConnectionAddressData s_DefaultConnectionAddressData = new ConnectionAddressData { Address = "127.0.0.1", Port = 7777, ServerListenAddress = "0.0.0.0" };
 
 #pragma warning disable IDE1006 // Naming Styles
 
@@ -303,9 +303,9 @@ public struct ConnectionAddressData
             public ushort Port;
 
             /// <summary>
-            /// IP address the server will listen on. If not provided, will use 'Address'.
+            /// IP address the server will listen on. If not provided, will use 0.0.0.0.
             /// </summary>
-            [Tooltip("IP address the server will listen on. If not provided, will use 'Address'.")]
+            [Tooltip("IP address the server will listen on. If not provided, will use 0.0.0.0.")]
             [SerializeField]
             public string ServerListenAddress;
 
@@ -330,7 +330,21 @@ private static NetworkEndpoint ParseNetworkEndpoint(string ip, ushort port)
             /// <summary>
             /// Endpoint (IP address and port) server will listen/bind on.
             /// </summary>
-            public NetworkEndpoint ListenEndPoint => ParseNetworkEndpoint((ServerListenAddress?.Length == 0) ? Address : ServerListenAddress, Port);
+            public NetworkEndpoint ListenEndPoint
+            {
+                get
+                {
+                    if (ServerListenAddress?.Length == 0)
+                    {
+                        var ep = ServerEndPoint.Family == NetworkFamily.Ipv4 ? NetworkEndpoint.AnyIpv4 : NetworkEndpoint.AnyIpv6;
+                        return ep.WithPort(Port);
+                    }
+                    else
+                    {
+                        return ParseNetworkEndpoint(ServerListenAddress, Port);
+                    }
+                }
+            }
         }
 
         /// <summary>
@@ -529,14 +543,14 @@ private bool ServerBindAndListen(NetworkEndpoint endPoint)
             int result = m_Driver.Bind(endPoint);
             if (result != 0)
             {
-                Debug.LogError("Server failed to bind");
+                Debug.LogError("Server failed to bind. This is usually caused by another process being bound to the same port.");
                 return false;
             }
 
             result = m_Driver.Listen();
             if (result != 0)
             {
-                Debug.LogError("Server failed to listen");
+                Debug.LogError("Server failed to listen.");
                 return false;
             }
 

com.unity.netcode.gameobjects/Tests/Editor/Transports/UnityTransportTests.cs

@@ -115,13 +115,13 @@ public void UnityTransport_RestartSucceedsAfterFailure()
             UnityTransport transport = new GameObject().AddComponent<UnityTransport>();
             transport.Initialize();
 
-            transport.SetConnectionData("127.0.0.", 4242);
+            transport.SetConnectionData("127.0.0.", 4242, "127.0.0.");
             Assert.False(transport.StartServer());
 
             LogAssert.Expect(LogType.Error, "Invalid network endpoint: 127.0.0.:4242.");
-            LogAssert.Expect(LogType.Error, "Server failed to bind");
+            LogAssert.Expect(LogType.Error, "Server failed to bind. This is usually caused by another process being bound to the same port.");
 
-            transport.SetConnectionData("127.0.0.1", 4242);
+            transport.SetConnectionData("127.0.0.1", 4242, "127.0.0.1");
             Assert.True(transport.StartServer());
 
             transport.Shutdown();