doctor can now disconnect

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();
         }