add "dual mode" socket for possible fix ios problems.

Author: RevenantX

LibSample/BroadcastTest.cs

@@ -112,8 +112,11 @@ public void Run()
             //Server
             _serverListener = new ServerListener();
 
-            NetManager server = new NetManager(_serverListener);
-            server.BroadcastReceiveEnabled = true;
+            NetManager server = new NetManager(_serverListener)
+            {
+                BroadcastReceiveEnabled = true, 
+                IPv6Enabled = IPv6Mode.DualMode
+            };
             if (!server.Start(9050))
             {
                 Console.WriteLine("Server start failed");
@@ -129,7 +132,8 @@ public void Run()
             {
                 UnconnectedMessagesEnabled = true, 
                 SimulateLatency = true, 
-                SimulationMaxLatency = 1500
+                SimulationMaxLatency = 1500,
+                IPv6Enabled = IPv6Mode.DualMode
             };
             _clientListener1.Client = client1;
             if (!client1.Start())
@@ -144,7 +148,8 @@ public void Run()
             {
                 UnconnectedMessagesEnabled = true,
                 SimulateLatency = true, 
-                SimulationMaxLatency = 1500
+                SimulationMaxLatency = 1500,
+                IPv6Enabled = IPv6Mode.DualMode
             };
 
             _clientListener2.Client = client2;

LibSample/HolePunchServerTest.cs

@@ -122,23 +122,23 @@ public void Run()
 
             _c1 = new NetManager(clientListener)
             {
-                IPv6Enabled = false,
+                IPv6Enabled = IPv6Mode.DualMode,
                 NatPunchEnabled = true
             };
             _c1.NatPunchModule.Init(natPunchListener1);
             _c1.Start();
 
             _c2 = new NetManager(clientListener)
             {
-                IPv6Enabled = false,
+                IPv6Enabled = IPv6Mode.DualMode,
                 NatPunchEnabled = true
             };
             _c2.NatPunchModule.Init(natPunchListener2);
             _c2.Start();
 
             _puncher = new NetManager(clientListener)
             {
-                IPv6Enabled = false,
+                IPv6Enabled = IPv6Mode.DualMode,
                 NatPunchEnabled = true
             };
             _puncher.Start(ServerPort);

LiteNetLib/NetManager.cs

@@ -10,6 +10,13 @@
 
 namespace LiteNetLib
 {
+    public enum IPv6Mode
+    {
+        Disabled,
+        SeparateSocket,
+        DualMode
+    }
+
     public sealed class NetPacketReader : NetDataReader
     {
         private NetPacket _packet;
@@ -284,7 +291,7 @@ private struct IncomingData
         /// <summary>
         /// IPv6 support
         /// </summary>
-        public bool IPv6Enabled = true;
+        public IPv6Mode IPv6Enabled = IPv6Mode.SeparateSocket;
 
         /// <summary>
         /// First peer. Useful for Client mode

LiteNetLib/NetSocket.cs

@@ -21,7 +21,7 @@ public class UnitySocketFix : MonoBehaviour
         internal IPAddress BindAddrIPv4;
         internal IPAddress BindAddrIPv6;
         internal bool Reuse;
-        internal bool IPv6;
+        internal IPv6Mode IPv6;
         internal int Port;
         internal bool Paused;
         internal NetSocket Socket;
@@ -68,7 +68,7 @@ internal sealed class NetSocket
         private Thread _threadv6;
         private readonly INetSocketListener _listener;
         private const int SioUdpConnreset = -1744830452; //SIO_UDP_CONNRESET = IOC_IN | IOC_VENDOR | 12
-        private static readonly IPAddress MulticastAddressV6 = IPAddress.Parse("FF02:0:0:0:0:0:0:1");
+        private static readonly IPAddress MulticastAddressV6 = IPAddress.Parse("ff02::1");
         internal static readonly bool IPv6Support;
 #if UNITY_IOS && !UNITY_EDITOR
         private UnitySocketFix _unitySocketFix;
@@ -84,8 +84,19 @@ public void OnErrorRestore()
 
         public short Ttl
         {
-            get { return _udpSocketv4.Ttl; }
-            set { _udpSocketv4.Ttl = value; }
+            get
+            {
+                if (_udpSocketv4.AddressFamily == AddressFamily.InterNetworkV6)
+                    return (short)_udpSocketv4.GetSocketOption(SocketOptionLevel.IPv6, SocketOptionName.HopLimit);
+                return _udpSocketv4.Ttl;
+            }
+            set
+            {
+                if (_udpSocketv4.AddressFamily == AddressFamily.InterNetworkV6)
+                    _udpSocketv4.SetSocketOption(SocketOptionLevel.IPv6, SocketOptionName.HopLimit, value);
+                else
+                    _udpSocketv4.Ttl = value;
+            }
         }
 
         static NetSocket()
@@ -174,13 +185,18 @@ private void ReceiveLogic(object state)
             }
         }
 
-        public bool Bind(IPAddress addressIPv4, IPAddress addressIPv6, int port, bool reuseAddress, bool ipv6)
+        public bool Bind(IPAddress addressIPv4, IPAddress addressIPv6, int port, bool reuseAddress, IPv6Mode ipv6Mode)
         {
             if (IsActive())
                 return false;
+            bool dualMode = ipv6Mode == IPv6Mode.DualMode && IPv6Support;
 
-            _udpSocketv4 = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
-            if (!BindSocket(_udpSocketv4, new IPEndPoint(addressIPv4, port), reuseAddress))
+            _udpSocketv4 = new Socket(
+                dualMode ? AddressFamily.InterNetworkV6 : AddressFamily.InterNetwork, 
+                SocketType.Dgram, 
+                ProtocolType.Udp);
+
+            if (!BindSocket(_udpSocketv4, new IPEndPoint(dualMode ? addressIPv6 : addressIPv4, port), reuseAddress, ipv6Mode))
                 return false;
 #if UNITY_IOS && !UNITY_EDITOR
             if (_unitySocketFix == null)
@@ -193,11 +209,13 @@ public bool Bind(IPAddress addressIPv4, IPAddress addressIPv6, int port, bool re
                 _unitySocketFix.BindAddrIPv6 = addressIPv6;
                 _unitySocketFix.Reuse = reuseAddress;
                 _unitySocketFix.Port = port;
-                _unitySocketFix.IPv6 = ipv6;
+                _unitySocketFix.IPv6 = ipv6Mode;
             }
 #endif
+            if (dualMode)
+                _udpSocketv6 = _udpSocketv4;
 
-            LocalPort = ((IPEndPoint)_udpSocketv4.LocalEndPoint).Port;
+            LocalPort = ((IPEndPoint) _udpSocketv4.LocalEndPoint).Port;
             IsRunning = true;
             _threadv4 = new Thread(ReceiveLogic)
             {
@@ -207,27 +225,13 @@ public bool Bind(IPAddress addressIPv4, IPAddress addressIPv6, int port, bool re
             _threadv4.Start(_udpSocketv4);
 
             //Check IPv6 support
-            if (!IPv6Support || !ipv6)
+            if (!IPv6Support || ipv6Mode != IPv6Mode.SeparateSocket)
                 return true;
 
             _udpSocketv6 = new Socket(AddressFamily.InterNetworkV6, SocketType.Dgram, ProtocolType.Udp);
             //Use one port for two sockets
-            if (BindSocket(_udpSocketv6, new IPEndPoint(addressIPv6, LocalPort), reuseAddress))
+            if (BindSocket(_udpSocketv6, new IPEndPoint(addressIPv6, LocalPort), reuseAddress, ipv6Mode))
             {
-                try
-                {
-#if !UNITY
-                    _udpSocketv6.SetSocketOption(
-                        SocketOptionLevel.IPv6,
-                        SocketOptionName.AddMembership,
-                        new IPv6MulticastOption(MulticastAddressV6));
-#endif
-                }
-                catch (Exception)
-                {
-                    // Unity3d throws exception - ignored
-                }
-
                 _threadv6 = new Thread(ReceiveLogic)
                 {
                     Name = "SocketThreadv6(" + LocalPort + ")",
@@ -239,7 +243,7 @@ public bool Bind(IPAddress addressIPv4, IPAddress addressIPv6, int port, bool re
             return true;
         }
 
-        private bool BindSocket(Socket socket, IPEndPoint ep, bool reuseAddress)
+        private bool BindSocket(Socket socket, IPEndPoint ep, bool reuseAddress, IPv6Mode ipv6Mode)
         {
             //Setup socket
             socket.ReceiveTimeout = 500;
@@ -271,7 +275,7 @@ private bool BindSocket(Socket socket, IPEndPoint ep, bool reuseAddress)
             }
             if (socket.AddressFamily == AddressFamily.InterNetwork)
             {
-                socket.Ttl = NetConstants.SocketTTL;
+                Ttl = NetConstants.SocketTTL;
 
 #if NETSTANDARD || NETCOREAPP
                 if(!RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
@@ -288,23 +292,57 @@ private bool BindSocket(Socket socket, IPEndPoint ep, bool reuseAddress)
                     NetDebug.WriteError("[B]Broadcast error: {0}", e.SocketErrorCode);
                 }
             }
+            else //IPv6 specific
+            {
+                if (ipv6Mode == IPv6Mode.DualMode)
+                {
+                    try
+                    {
+                        //Disable IPv6 only mode
+                        socket.SetSocketOption(SocketOptionLevel.IPv6, (SocketOptionName)27, false);
+                    }
+                    catch(Exception e)
+                    {
+                        NetDebug.WriteError("[B]Bind exception (dualmode setting): {0}", e.ToString());
+                    }
+                }
+            }
 
             //Bind
             try
             {
                 socket.Bind(ep);
                 NetDebug.Write(NetLogLevel.Trace, "[B]Successfully binded to port: {0}", ((IPEndPoint)socket.LocalEndPoint).Port);
+
+                //join multicast
+                if (socket.AddressFamily == AddressFamily.InterNetworkV6)
+                {
+                    try
+                    {
+#if !UNITY
+                        socket.SetSocketOption(
+                            SocketOptionLevel.IPv6,
+                            SocketOptionName.AddMembership,
+                            new IPv6MulticastOption(MulticastAddressV6));
+#endif
+                    }
+                    catch (Exception)
+                    {
+                        // Unity3d throws exception - ignored
+                    }
+                }
             }
             catch (SocketException bindException)
             {
                 switch (bindException.SocketErrorCode)
                 {
                     //IPv6 bind fix
                     case SocketError.AddressAlreadyInUse:
-                        if (socket.AddressFamily == AddressFamily.InterNetworkV6)
+                        if (socket.AddressFamily == AddressFamily.InterNetworkV6 && ipv6Mode != IPv6Mode.DualMode)
                         {
                             try
                             {
+                                //Set IPv6Only
                                 socket.SetSocketOption(SocketOptionLevel.IPv6, (SocketOptionName)27, true);
                                 socket.Bind(ep);
                             }
@@ -412,6 +450,9 @@ public void Close(bool suspend)
                 _unitySocketFix = null;
 #endif
             }
+            //cleanup dual mode
+            if (_udpSocketv4 == _udpSocketv6)
+                _udpSocketv6 = null;
 
             if (_udpSocketv4 != null)
                 _udpSocketv4.Close();

LiteNetLib/Utils/NtpRequest.cs

@@ -37,7 +37,12 @@ private NtpRequest(IPEndPoint endPoint, Action<NtpPacket> onRequestComplete)
 
             // Create and start socket
             _socket = new NetSocket(this);
-            _socket.Bind(IPAddress.Any, IPAddress.IPv6Any, 0, false, endPoint.AddressFamily == AddressFamily.InterNetworkV6);
+            _socket.Bind(
+                IPAddress.Any, 
+                IPAddress.IPv6Any, 
+                0, 
+                false, 
+                endPoint.AddressFamily == AddressFamily.InterNetworkV6 ? IPv6Mode.SeparateSocket : IPv6Mode.Disabled);
         }
 
         /// <summary>