Close Client Socket on disconnect

I have server application that listens for clients. Let's client lost internet connection and lost connection with server.

Does server automatically check when a client was disconnected? If not how may I implement such thing?

Main.cs http://pastebin.com/fHYpErz7

ServerSocket.cs: http://pastebin.com/erw4tzdp

Client.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;

namespace jM2
{
    class Client
    {
        private int clientConnectionID;
        private Socket clientSocket;
        private string clientIP;
        private byte[] clientBuffer = new byte[1024];

        public Client(int connectionID开发者_JAVA技巧, Socket connectionSocket)
        {
            clientConnectionID = connectionID;
            clientSocket = connectionSocket;
            clientIP = connectionSocket.RemoteEndPoint.ToString();
            clientSocket.BeginReceive(clientBuffer, 0, clientBuffer.Length, SocketFlags.None, new AsyncCallback(dataArrival), null);
        }
        public void Disconnect()
        {
            clientSocket.Close();
        }
        private void dataArrival(IAsyncResult iar)
        {
            int bytesReceived = clientSocket.EndReceive(iar);
            clientSocket.BeginReceive(clientBuffer, 0, clientBuffer.Length, SocketFlags.None, new AsyncCallback(dataArrival), null);
        }
    }
}

See my answer to this question:

TcpClient.Close doesn't close the connection

Basically no one knows if the connection is closed until you try to send data. If it fails, the connection is closed.

Based on what Chris Haas said, I may be wrong, however I have previously written a TCP server and detected closed connections when I received 0 bytes. In other words, in your dataArrival method, if bytesReceived was 0, this would indicate the connection had closed. This seemed to work through fairly extensive testing.

I recommend a type of "poll" or "heartbeat" message, as described here.