Improve connection disposal.

Source/MQTTnet/Adapter/IMqttServerAdapter.cs

@@ -6,7 +6,7 @@ namespace MQTTnet.Adapter
 {
     public interface IMqttServerAdapter : IDisposable
     {
-        Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
+        Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
 
         Task StartAsync(IMqttServerOptions options);
         Task StopAsync();

Source/MQTTnet/Adapter/MqttServerAdapterClientAcceptedEventArgs.cs

@@ -1,17 +0,0 @@
-using System;
-using System.Threading.Tasks;
-
-namespace MQTTnet.Adapter
-{
-    public class MqttServerAdapterClientAcceptedEventArgs : EventArgs
-    {
-        public MqttServerAdapterClientAcceptedEventArgs(IMqttChannelAdapter channelAdapter)
-        {
-            ChannelAdapter = channelAdapter ?? throw new ArgumentNullException(nameof(channelAdapter));
-        }
-
-        public IMqttChannelAdapter ChannelAdapter { get; }
-
-        public Task SessionTask { get; set; }
-    }
-}

Source/MQTTnet/Implementations/MqttTcpServerAdapter.Uwp.cs

@@ -23,7 +23,7 @@ namespace MQTTnet.Implementations
             _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
         }
 
-        public Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
+        public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
 
         public async Task StartAsync(IMqttServerOptions options)
         {
@@ -39,7 +39,7 @@ namespace MQTTnet.Implementations
                 _listener.Control.NoDelay = options.DefaultEndpointOptions.NoDelay;
                 _listener.Control.KeepAlive = true;
                 _listener.Control.QualityOfService = SocketQualityOfService.LowLatency;
-                _listener.ConnectionReceived += AcceptDefaultEndpointConnectionsAsync;
+                _listener.ConnectionReceived += OnConnectionReceivedAsync;
                 
                 await _listener.BindServiceNameAsync(options.DefaultEndpointOptions.Port.ToString(), SocketProtectionLevel.PlainSocket);
             }
@@ -54,30 +54,51 @@ namespace MQTTnet.Implementations
         {
             if (_listener != null)
             {
-                _listener.ConnectionReceived -= AcceptDefaultEndpointConnectionsAsync;
+                _listener.ConnectionReceived -= OnConnectionReceivedAsync;
             }
 
-            _listener?.Dispose();
-            _listener = null;
-
             return Task.FromResult(0);
         }
 
         public void Dispose()
         {
-            StopAsync().GetAwaiter().GetResult();
+            _listener?.Dispose();
+            _listener = null;
         }
 
-        private void AcceptDefaultEndpointConnectionsAsync(StreamSocketListener sender, StreamSocketListenerConnectionReceivedEventArgs args)
+        private async void OnConnectionReceivedAsync(StreamSocketListener sender, StreamSocketListenerConnectionReceivedEventArgs args)
         {
             try
             {
-                var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(args.Socket, _options), new MqttPacketFormatterAdapter(), _logger);
-                ClientAcceptedHandler?.Invoke(new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
+                var clientHandler = ClientHandler;
+                if (clientHandler != null)
+                {
+                    using (var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(args.Socket, _options), new MqttPacketFormatterAdapter(), _logger))
+                    {
+                        await clientHandler(clientAdapter).ConfigureAwait(false);
+                    }
+                }
             }
             catch (Exception exception)
             {
-                _logger.Error(exception, "Error while accepting connection at default endpoint.");
+                if (exception is ObjectDisposedException)
+                {
+                    // It can happen that the listener socket is accessed after the cancellation token is already set and the listener socket is disposed.
+                    return;
+                }
+
+                _logger.Error(exception, "Error while handling client connection.");
+            }
+            finally
+            {
+                try
+                {
+                    args.Socket.Dispose();
+                }
+                catch (Exception exception)
+                { 
+                    _logger.Error(exception, "Error while cleaning up client connection");
+                }
             }
         }
     }

Source/MQTTnet/Implementations/MqttTcpServerAdapter.cs

@@ -26,7 +26,7 @@ namespace MQTTnet.Implementations
             _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
         }
 
-        public Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
+        public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
 
         public Task StartAsync(IMqttServerOptions options)
         {
@@ -89,7 +89,7 @@ namespace MQTTnet.Implementations
                     _cancellationTokenSource.Token,
                     _logger)
                 {
-                    ClientAcceptedHandler = OnClientAccepted
+                    ClientHandler = OnClientAcceptedAsync
                 };
 
                 listenerV4.Start();
@@ -105,7 +105,7 @@ namespace MQTTnet.Implementations
                     _cancellationTokenSource.Token,
                     _logger)
                 {
-                    ClientAcceptedHandler = OnClientAccepted
+                    ClientHandler = OnClientAcceptedAsync
                 };
 
                 listenerV6.Start();
@@ -113,9 +113,15 @@ namespace MQTTnet.Implementations
             }
         }
 
-        private void OnClientAccepted(MqttServerAdapterClientAcceptedEventArgs eventArgs)
+        private Task OnClientAcceptedAsync(IMqttChannelAdapter channelAdapter)
         {
-            ClientAcceptedHandler?.Invoke(eventArgs);
+            var clientHandler = ClientHandler;
+            if (clientHandler == null)
+            {
+                return Task.FromResult(0);
+            }
+
+            return clientHandler(channelAdapter);
         }
     }
 }

Source/MQTTnet/Implementations/MqttTcpServerListener.cs

@@ -43,7 +43,7 @@ namespace MQTTnet.Implementations
             }
         }
 
-        public Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
+        public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
 
         public void Start()
         {
@@ -97,11 +97,14 @@ namespace MQTTnet.Implementations
         private async Task TryHandleClientConnectionAsync(Socket clientSocket)
         {
             Stream stream = null;
+            EndPoint remoteEndPoint = null;
 
             try
             {
+                remoteEndPoint = clientSocket.RemoteEndPoint;
+
                 _logger.Verbose("Client '{0}' accepted by TCP listener '{1}, {2}'.",
-                    clientSocket.RemoteEndPoint,
+                    remoteEndPoint,
                     _socket.LocalEndPoint,
                     _addressFamily == AddressFamily.InterNetwork ? "ipv4" : "ipv6");
 
@@ -116,8 +119,14 @@ namespace MQTTnet.Implementations
                     stream = sslStream;
                 }
 
-                var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(stream), new MqttPacketFormatterAdapter(), _logger);
-                ClientAcceptedHandler?.Invoke(new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
+                var clientHandler = ClientHandler;
+                if (clientHandler != null)
+                {
+                    using (var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(stream), new MqttPacketFormatterAdapter(), _logger))
+                    {
+                        await clientHandler(clientAdapter).ConfigureAwait(false);
+                    }
+                }
             }
             catch (Exception exception)
             {
@@ -127,20 +136,29 @@ namespace MQTTnet.Implementations
                     return;
                 }
 
-                if (exception is SocketException socketException && socketException.SocketErrorCode == SocketError.OperationAborted)
+                if (exception is SocketException socketException &&
+                    socketException.SocketErrorCode == SocketError.OperationAborted)
                 {
                     return;
                 }
 
+                _logger.Error(exception, "Error while handling client connection.");
+            }
+            finally
+            {
                 try
                 {
-                    // Dispose already allocated resources.
                     stream?.Dispose();
                     clientSocket?.Dispose();
+
+                    _logger.Verbose("Client '{0}' disconnected at TCP listener '{1}, {2}'.",
+                        remoteEndPoint,
+                        _socket.LocalEndPoint,
+                        _addressFamily == AddressFamily.InterNetwork ? "ipv4" : "ipv6");
                 }
                 catch (Exception disposeException)
                 {
-                    _logger.Error(disposeException, "Error while cleanup of broken connection.");
+                    _logger.Error(disposeException, "Error while cleaning up client connection");
                 }
             }
         }

Source/MQTTnet/Implementations/MqttWebSocketChannel.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Globalization;
 using System.Net;
 using System.Net.WebSockets;
 using System.Security.Cryptography.X509Certificates;

Source/MQTTnet/Server/MqttClientConnection.cs

@@ -27,12 +27,12 @@ namespace MQTTnet.Server
         private readonly IMqttNetChildLogger _logger;
         private readonly IMqttServerOptions _serverOptions;
 
-        private Task<MqttClientDisconnectType> _packageReceiverTask;
         private readonly IMqttChannelAdapter _channelAdapter;
         private readonly IMqttDataConverter _dataConverter;
         private readonly string _endpoint;
         private readonly MqttConnectPacket _connectPacket;
 
+        private Task<MqttClientDisconnectType> _packageReceiverTask;
         private DateTime _lastPacketReceivedTimestamp;
         private DateTime _lastNonKeepAlivePacketReceivedTimestamp;
 
@@ -78,7 +78,7 @@ namespace MQTTnet.Server
             StopInternal();
 
             var task = _packageReceiverTask;
-            if (task != null && !task.IsCompleted)
+            if (task != null)
             {
                 await task.ConfigureAwait(false);
             }
@@ -103,13 +103,6 @@ namespace MQTTnet.Server
             status.BytesReceived = _channelAdapter.BytesReceived;
         }
         
-        //public void ClearPendingApplicationMessages()
-        //{
-        //    Session.ApplicationMessagesQueue.Clear();
-
-        //    //_applicationMessagesQueue.Clear();
-        //}
-
         public void Dispose()
         {
             _cancellationToken.Dispose();

Source/MQTTnet/Server/MqttClientSessionsManager.cs

@@ -57,9 +57,9 @@ namespace MQTTnet.Server
             }
         }
 
-        public Task HandleConnectionAsync(IMqttChannelAdapter clientAdapter)
+        public Task HandleClientAsync(IMqttChannelAdapter clientAdapter)
         {
-            return HandleConnectionAsync(clientAdapter, _cancellationToken);
+            return HandleClientAsync(clientAdapter, _cancellationToken);
         }
 
         public Task<IList<IMqttClientStatus>> GetClientStatusAsync()
@@ -221,7 +221,7 @@ namespace MQTTnet.Server
             }
         }
 
-        private async Task HandleConnectionAsync(IMqttChannelAdapter channelAdapter, CancellationToken cancellationToken)
+        private async Task HandleClientAsync(IMqttChannelAdapter channelAdapter, CancellationToken cancellationToken)
         {
             var disconnectType = MqttClientDisconnectType.NotClean;
             var clientId = string.Empty;
@@ -376,10 +376,6 @@ namespace MQTTnet.Server
             {
                 _logger.Error(exception, "Error while disconnecting client channel.");
             }
-            finally
-            {
-                channelAdapter.Dispose();
-            }
         }
     }
 }

Source/MQTTnet/Server/MqttServer.cs

@@ -127,7 +127,7 @@ namespace MQTTnet.Server
 
             foreach (var adapter in _adapters)
             {
-                adapter.ClientAcceptedHandler = OnClientAccepted;
+                adapter.ClientHandler = OnHandleClient;
                 await adapter.StartAsync(Options).ConfigureAwait(false);
             }
 
@@ -155,7 +155,7 @@ namespace MQTTnet.Server
 
                 foreach (var adapter in _adapters)
                 {
-                    adapter.ClientAcceptedHandler = null;
+                    adapter.ClientHandler = null;
                     await adapter.StopAsync().ConfigureAwait(false);
                 }
 
@@ -184,9 +184,9 @@ namespace MQTTnet.Server
             return _retainedMessagesManager?.ClearMessagesAsync();
         }
 
-        private void OnClientAccepted(MqttServerAdapterClientAcceptedEventArgs eventArgs)
+        private Task OnHandleClient(IMqttChannelAdapter channelAdapter)
         {
-            eventArgs.SessionTask = _clientSessionsManager.HandleConnectionAsync(eventArgs.ChannelAdapter);
+            return _clientSessionsManager.HandleClientAsync(channelAdapter);
         }
     }
 }