feature: KcpServer.DualMode is now configurable in the constructor instead of using #if UNITY_SWITCH

Author: vis2k

kcp2k/Assets/Example/TestServer.cs

@@ -14,6 +14,7 @@ public class TestServer : MonoBehaviour
             (connectionId) => {},
             (connectionId, message) => Debug.Log($"KCP: OnServerDataReceived({connectionId}, {BitConverter.ToString(message.Array, message.Offset, message.Count)})"),
             (connectionId) => {},
+            false,
             true,
             10
         );

kcp2k/Assets/Tests/Editor/ClientServerTests.cs

@@ -14,6 +14,9 @@ public class ClientServerTests
         // this way UpdateSeveralTimes() doesn't need to wait very long and
         // tests run a lot faster.
         const ushort Port = 7777;
+        // not all platforms support DualMode.
+        // run tests without it so they work on all platforms.
+        const bool DualMode = false;
         const bool NoDelay = true;
         const uint Interval = 1; // 1ms so at interval code at least runs.
         const int Timeout = 2000;
@@ -65,6 +68,7 @@ public void SetUp()
                 (connectionId) => {},
                 ServerOnData,
                 (connectionId) => {},
+                DualMode,
                 NoDelay,
                 Interval,
                 0,
@@ -746,7 +750,10 @@ public void ServerGetClientAddress()
             ConnectClientBlocking();
             int connectionId = ServerFirstConnectionId();
 
-            Assert.That(server.GetClientAddress(connectionId), Is.EqualTo("::ffff:127.0.0.1"));
+            if (server.DualMode)
+                Assert.That(server.GetClientAddress(connectionId), Is.EqualTo("::ffff:127.0.0.1"));
+            else
+                Assert.That(server.GetClientAddress(connectionId), Is.EqualTo("127.0.0.1"));
         }
 
         [Test]

kcp2k/Assets/kcp2k/highlevel/KcpServer.cs

@@ -15,6 +15,9 @@ public class KcpServer
         public Action<int> OnDisconnected;
 
         // configuration
+        // DualMode uses both IPv6 and IPv4. not all platforms support it.
+        // (Nintendo Switch, etc.)
+        public bool DualMode;
         // NoDelay is recommended to reduce latency. This also scales better
         // without buffers getting full.
         public bool NoDelay;
@@ -41,12 +44,8 @@ public class KcpServer
 
         // state
         Socket socket;
-#if UNITY_SWITCH
-        // switch does not support ipv6
-        EndPoint newClientEP = new IPEndPoint(IPAddress.Any, 0);
-#else
-        EndPoint newClientEP = new IPEndPoint(IPAddress.IPv6Any, 0);
-#endif
+        EndPoint newClientEP;
+
         // IMPORTANT: raw receive buffer always needs to be of 'MTU' size, even
         //            if MaxMessageSize is larger. kcp always sends in MTU
         //            segments and having a buffer smaller than MTU would
@@ -60,6 +59,7 @@ public class KcpServer
         public KcpServer(Action<int> OnConnected,
                          Action<int, ArraySegment<byte>> OnData,
                          Action<int> OnDisconnected,
+                         bool DualMode,
                          bool NoDelay,
                          uint Interval,
                          int FastResend = 0,
@@ -71,13 +71,19 @@ public KcpServer(Action<int> OnConnected,
             this.OnConnected = OnConnected;
             this.OnData = OnData;
             this.OnDisconnected = OnDisconnected;
+            this.DualMode = DualMode;
             this.NoDelay = NoDelay;
             this.Interval = Interval;
             this.FastResend = FastResend;
             this.CongestionWindow = CongestionWindow;
             this.SendWindowSize = SendWindowSize;
             this.ReceiveWindowSize = ReceiveWindowSize;
             this.Timeout = Timeout;
+
+            // create newClientEP either IPv4 or IPv6
+            newClientEP = DualMode
+                          ? new IPEndPoint(IPAddress.IPv6Any, 0)
+                          : new IPEndPoint(IPAddress.Any, 0);
         }
 
         public bool IsActive() => socket != null;
@@ -91,15 +97,19 @@ public void Start(ushort port)
             }
 
             // listen
-#if UNITY_SWITCH
-            // Switch does not support ipv6
-            socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
-            socket.Bind(new IPEndPoint(IPAddress.Any, port));
-#else
-            socket = new Socket(AddressFamily.InterNetworkV6, SocketType.Dgram, ProtocolType.Udp);
-            socket.DualMode = true;
-            socket.Bind(new IPEndPoint(IPAddress.IPv6Any, port));
-#endif
+            if (DualMode)
+            {
+                // IPv6 socket with DualMode
+                socket = new Socket(AddressFamily.InterNetworkV6, SocketType.Dgram, ProtocolType.Udp);
+                socket.DualMode = true;
+                socket.Bind(new IPEndPoint(IPAddress.IPv6Any, port));
+            }
+            else
+            {
+                // IPv4 socket
+                socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
+                socket.Bind(new IPEndPoint(IPAddress.Any, port));
+            }
         }
 
         public void Send(int connectionId, ArraySegment<byte> segment, KcpChannel channel)