/* * Copyright (c) 2006, Clutch, Inc. * Original Author: Jeff Cesnik * All rights reserved. * * - Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * - Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * - Neither the name of the openmetaverse.org nor the names * of its contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ using System; using System.Net; using System.Net.Sockets; using System.Threading; using log4net; namespace OpenMetaverse { /// <summary> /// Base UDP server /// </summary> public abstract class OpenSimUDPBase { private static readonly ILog m_log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType); /// <summary> /// This method is called when an incoming packet is received /// </summary> /// <param name="buffer">Incoming packet buffer</param> protected abstract void PacketReceived(UDPPacketBuffer buffer); /// <summary>UDP port to bind to in server mode</summary> protected int m_udpPort; /// <summary>Local IP address to bind to in server mode</summary> protected IPAddress m_localBindAddress; /// <summary>UDP socket, used in either client or server mode</summary> private Socket m_udpSocket; /// <summary>Flag to process packets asynchronously or synchronously</summary> private bool m_asyncPacketHandling; /// <summary>The all important shutdown flag</summary> private volatile bool m_shutdownFlag = true; /// <summary>Returns true if the server is currently listening, otherwise false</summary> public bool IsRunning { get { return !m_shutdownFlag; } } /// <summary> /// Default constructor /// </summary> /// <param name="bindAddress">Local IP address to bind the server to</param> /// <param name="port">Port to listening for incoming UDP packets on</param> public OpenSimUDPBase(IPAddress bindAddress, int port) { m_localBindAddress = bindAddress; m_udpPort = port; } /// <summary> /// Start the UDP server /// </summary> /// <param name="recvBufferSize">The size of the receive buffer for /// the UDP socket. This value is passed up to the operating system /// and used in the system networking stack. Use zero to leave this /// value as the default</param> /// <param name="asyncPacketHandling">Set this to true to start /// receiving more packets while current packet handler callbacks are /// still running. Setting this to false will complete each packet /// callback before the next packet is processed</param> /// <remarks>This method will attempt to set the SIO_UDP_CONNRESET flag /// on the socket to get newer versions of Windows to behave in a sane /// manner (not throwing an exception when the remote side resets the /// connection). This call is ignored on Mono where the flag is not /// necessary</remarks> public void Start(int recvBufferSize, bool asyncPacketHandling) { m_asyncPacketHandling = asyncPacketHandling; if (m_shutdownFlag) { const int SIO_UDP_CONNRESET = -1744830452; IPEndPoint ipep = new IPEndPoint(m_localBindAddress, m_udpPort); m_udpSocket = new Socket( AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); try { // This udp socket flag is not supported under mono, // so we'll catch the exception and continue m_udpSocket.IOControl(SIO_UDP_CONNRESET, new byte[] { 0 }, null); m_log.Debug("[UDPBASE]: SIO_UDP_CONNRESET flag set"); } catch (SocketException) { m_log.Debug("[UDPBASE]: SIO_UDP_CONNRESET flag not supported on this platform, ignoring"); } if (recvBufferSize != 0) m_udpSocket.ReceiveBufferSize = recvBufferSize; m_udpSocket.Bind(ipep); // we're not shutting down, we're starting up m_shutdownFlag = false; // kick off an async receive. The Start() method will return, the // actual receives will occur asynchronously and will be caught in // AsyncEndRecieve(). AsyncBeginReceive(); } } /// <summary> /// Stops the UDP server /// </summary> public void Stop() { if (!m_shutdownFlag) { // wait indefinitely for a writer lock. Once this is called, the .NET runtime // will deny any more reader locks, in effect blocking all other send/receive // threads. Once we have the lock, we set shutdownFlag to inform the other // threads that the socket is closed. m_shutdownFlag = true; m_udpSocket.Close(); } } private void AsyncBeginReceive() { // allocate a packet buffer //WrappedObject<UDPPacketBuffer> wrappedBuffer = Pool.CheckOut(); UDPPacketBuffer buf = new UDPPacketBuffer(); if (!m_shutdownFlag) { try { // kick off an async read m_udpSocket.BeginReceiveFrom( //wrappedBuffer.Instance.Data, buf.Data, 0, UDPPacketBuffer.BUFFER_SIZE, SocketFlags.None, ref buf.RemoteEndPoint, AsyncEndReceive, //wrappedBuffer); buf); } catch (SocketException e) { if (e.SocketErrorCode == SocketError.ConnectionReset) { m_log.Warn("[UDPBASE]: SIO_UDP_CONNRESET was ignored, attempting to salvage the UDP listener on port " + m_udpPort); bool salvaged = false; while (!salvaged) { try { m_udpSocket.BeginReceiveFrom( //wrappedBuffer.Instance.Data, buf.Data, 0, UDPPacketBuffer.BUFFER_SIZE, SocketFlags.None, ref buf.RemoteEndPoint, AsyncEndReceive, //wrappedBuffer); buf); salvaged = true; } catch (SocketException) { } catch (ObjectDisposedException) { return; } } m_log.Warn("[UDPBASE]: Salvaged the UDP listener on port " + m_udpPort); } } catch (ObjectDisposedException) { } } } private void AsyncEndReceive(IAsyncResult iar) { // Asynchronous receive operations will complete here through the call // to AsyncBeginReceive if (!m_shutdownFlag) { // Asynchronous mode will start another receive before the // callback for this packet is even fired. Very parallel :-) if (m_asyncPacketHandling) AsyncBeginReceive(); // get the buffer that was created in AsyncBeginReceive // this is the received data //WrappedObject<UDPPacketBuffer> wrappedBuffer = (WrappedObject<UDPPacketBuffer>)iar.AsyncState; //UDPPacketBuffer buffer = wrappedBuffer.Instance; UDPPacketBuffer buffer = (UDPPacketBuffer)iar.AsyncState; try { // get the length of data actually read from the socket, store it with the // buffer buffer.DataLength = m_udpSocket.EndReceiveFrom(iar, ref buffer.RemoteEndPoint); // call the abstract method PacketReceived(), passing the buffer that // has just been filled from the socket read. PacketReceived(buffer); } catch (SocketException) { } catch (ObjectDisposedException) { } finally { //wrappedBuffer.Dispose(); // Synchronous mode waits until the packet callback completes // before starting the receive to fetch another packet if (!m_asyncPacketHandling) AsyncBeginReceive(); } } } public void AsyncBeginSend(UDPPacketBuffer buf) { if (!m_shutdownFlag) { try { m_udpSocket.BeginSendTo( buf.Data, 0, buf.DataLength, SocketFlags.None, buf.RemoteEndPoint, AsyncEndSend, buf); } catch (SocketException) { } catch (ObjectDisposedException) { } } } void AsyncEndSend(IAsyncResult result) { try { // UDPPacketBuffer buf = (UDPPacketBuffer)result.AsyncState; m_udpSocket.EndSendTo(result); } catch (SocketException) { } catch (ObjectDisposedException) { } } } }