chat afbrudt

Jeg har lavet dette lille chat program

Hvordan for jeg den til at sende en besked hvis forbindelsen bliver afbrudt

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Threading;



namespace WindowsApplication8
{
    public partial class Form1 : Form
    {
        private TcpClient client;
        private StreamReader rdr;
        private StreamWriter wrt;

        public Form1()
        {
            InitializeComponent();
            client = new TcpClient("localhost", 1234);
            rdr = new StreamReader(client.GetStream());
            wrt = new StreamWriter(client.GetStream());
            (new Thread(new ThreadStart(Reader))).Start();

        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }
        private void Reader()
        {
            string line;
            while ((line = rdr.ReadLine()) != null)
            {
                lock (msgs)
                {
                    msgs.Text += ("dig: " + line + "\r\n");
                }
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            wrt.WriteLine(sendmsg.Text);
            wrt.Flush();
            lock (msgs)
            {
                msgs.Text += ("mig: " + sendmsg.Text + "\r\n");
            }

        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            //MessageBox.Show("text");                       
           
            rdr.Close();
            wrt.Close();
            client.Close();
            Application.Exit();


        }

    }
}