UdpServer.cs :  » Business-Application » DC » DCSharp » Backend » Connections » C# / CSharp Open Source

/* 
 * Copyright (C) 2004-2005 Jonathan Bindel
 * Copyright (C) 2006 Eskil Bylund
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

using System;
using System.Collections;
using System.Diagnostics;
using System.Globalization;
using System.Net;
using System.Net.Sockets;
using System.Text;

using DCSharp.Backend.Protocols;
using DCSharp.Extras;

namespace DCSharp.Backend.Connections{
  public sealed class UdpServer : Server
  {
    private static UdpServer instance;
    private static Socket socket;

    private IProtocol protocol;
    
    private byte[] buffer;
    private AsyncCallback receivedData;

    public UdpServer(IPAddress localIP, int port, IProtocol protocol) :
      base(localIP, port)
    {
      if (protocol == null)
      {
        throw new ArgumentNullException("protocol");
      }
      this.protocol = protocol;
      
      buffer = new byte[40096];
      receivedData = new AsyncCallback(OnReceivedData);
    }

    #region Methods

    public static void StartListening(int port, IProtocol protocol)
    {
      StopListening();
      
      instance = new UdpServer(IPAddress.Any, port, protocol);
      instance.Start();
    }

    public static void StopListening()
    {
      if (instance != null)
      {
        instance.Stop();
        instance = null;
      }
    }

    protected override void ServerStart()
    {
      Listener = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,
        ProtocolType.Udp);
      Listener.Bind(new IPEndPoint(LocalIP, Port));
      
      BeginReceive();
    }
    
    private void BeginReceive()
    {
      Listener.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None,
        receivedData, Listener);
    }
    
    private void OnReceivedData(IAsyncResult result)
    {
      Socket socket = (Socket)result.AsyncState;
      int length = 0;
      
      try
      {
        length = socket.EndReceive(result);
      }
      catch (ObjectDisposedException)
      {
      }
      
      if (length > 0)
      {
        string message = protocol.Encoding.GetString(buffer, 0, length);
        try
        {
          protocol.Handle(message);
        }
        catch
        {
        }
        BeginReceive();
      }
    }

    public static void Send(IPEndPoint endPoint, string message)
    {
      Send(endPoint, message, Encoding.UTF8);
    }

    public static void Send(IPEndPoint endPoint, string message,
      Encoding encoding)
    {
      try
      {
        if (socket == null)
        {
          socket = new Socket(AddressFamily.InterNetwork,
            SocketType.Dgram, ProtocolType.Udp);
        }
        socket.SendTo(encoding.GetBytes(message), endPoint);
      }
      catch (Exception e)
      {
        Debug.WriteLine(e);
      }
    }

    public static void CloseSockets()
    {
      if (socket != null)
      {
        socket.Close();
        socket = null;
      }
    }

    #endregion
  }
}