ClientApp/Utils/EngineConnection.cs

@@ -44,7 +44,7 @@ namespace ClientApp.Utils
         private static string groundPlaneId = string.Empty;
         private static string terrainId = string.Empty;
 
-        public string DoctorMessage { get; set; };
+        public string DoctorMessage { get; set; }
         public float BikeSpeed { get; set; }
         public float BikePower { get; set; }
         public float BikeBPM { get; set; }
@@ -75,7 +75,7 @@ namespace ClientApp.Utils
             noVRResponseTimer.Elapsed += noVRResponseTimeout;
             noVRResponseTimer.AutoReset = false;
             noVRResponseTimer.Enabled = false;
-            
+
         }
 
         private void UpdateTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)

DoctorApp/Utils/Client.cs

@@ -130,6 +130,8 @@ namespace DoctorApp.Utils
                 expectedMessageLength = BitConverter.ToInt32(totalBuffer, 0);
             }
 
+            if (ar == null || (!ar.IsCompleted) || (!this.stream.CanRead) || !this.client.Connected)
+                return;
             this.stream.BeginRead(this.buffer, 0, this.buffer.Length, new AsyncCallback(OnRead), null);
 
         }
@@ -192,6 +194,7 @@ namespace DoctorApp.Utils
         public void Dispose()
         {
             Debug.WriteLine("client dispose called");
+            sendMessage(DataParser.getDisconnectJson(LoginViewModel.Username));
             this.stream.Dispose();
             this.client.Dispose();
         }

Server/Client.cs

@@ -65,7 +65,7 @@ namespace Server
                 }
             }
 
-            if (ar == null || (!ar.IsCompleted) || (!this.stream.CanRead))
+            if (ar == null || (!ar.IsCompleted) || (!this.stream.CanRead) || !this.tcpClient.Client.Connected)
                 return;
             this.stream.BeginRead(this.buffer, 0, this.buffer.Length, new AsyncCallback(OnRead), null);
 
@@ -123,7 +123,7 @@ namespace Server
                         //set resistance on doctor GUI
                         break;
                     case DataParser.DISCONNECT:
-                        communication.Disconnect(this);
+                        communication.LogOff(this);
                         break;
                     default:
                         Console.WriteLine($"Received json with identifier {identifier}:\n{Encoding.ASCII.GetString(payloadbytes)}");

Server/Communication.cs

@@ -19,11 +19,12 @@ namespace Server
             set
             {
                 this.mDoctor = value;
-                this.clients.ForEach((client) =>
-                {
-                    this.mDoctor.sendMessage(DataParser.getNewConnectionJson(client.username));
-                    client.sendMessage(DataParser.getNewConnectionJson(this.mDoctor.username));
-                });
+                if (this.mDoctor != null)
+                    this.clients.ForEach((client) =>
+                    {
+                        this.mDoctor.sendMessage(DataParser.getNewConnectionJson(client.username));
+                        client.sendMessage(DataParser.getNewConnectionJson(this.mDoctor.username));
+                    });
             }
         }
         public Communication(TcpListener listener)
@@ -50,12 +51,6 @@ namespace Server
             listener.BeginAcceptTcpClient(new AsyncCallback(OnConnect), null);
         }
 
-        internal void Disconnect(Client client)
-        {
-            clients.Remove(client);
-            Doctor.sendMessage(DataParser.getDisconnectJson(client.username));
-        }
-
         public void NewLogin(Client client)
         {
             this.clients.Add(client);
@@ -76,6 +71,7 @@ namespace Server
                 });
                 this.Doctor = null;
             }
+            Doctor?.sendMessage(DataParser.getDisconnectJson(client.username));
             this.clients.Remove(client);
         }