/*
* 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;
using OpenSim.Framework;
using OpenSim.Framework.Monitoring;
namespace OpenMetaverse
{
///
/// Base UDP server
///
public abstract class OpenSimUDPBase
{
private static readonly ILog m_log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
///
/// This method is called when an incoming packet is received
///
/// Incoming packet buffer
public abstract void PacketReceived(UDPPacketBuffer buffer);
/// UDP port to bind to in server mode
protected int m_udpPort;
/// Local IP address to bind to in server mode
protected IPAddress m_localBindAddress;
/// UDP socket, used in either client or server mode
private Socket m_udpSocket;
/// Flag to process packets asynchronously or synchronously
private bool m_asyncPacketHandling;
///
/// Are we to use object pool(s) to reduce memory churn when receiving data?
///
public bool UsePools { get; protected set; }
///
/// Pool to use for handling data. May be null if UsePools = false;
///
protected OpenSim.Framework.Pool Pool { get; private set; }
/// Returns true if the server is currently listening for inbound packets, otherwise false
public bool IsRunningInbound { get; private set; }
/// Returns true if the server is currently sending outbound packets, otherwise false
/// If IsRunningOut = false, then any request to send a packet is simply dropped.
public bool IsRunningOutbound { get; private set; }
///
/// Number of UDP receives.
///
public int UdpReceives { get; private set; }
///
/// Number of UDP sends
///
public int UdpSends { get; private set; }
///
/// Number of receives over which to establish a receive time average.
///
private readonly static int s_receiveTimeSamples = 500;
///
/// Current number of samples taken to establish a receive time average.
///
private int m_currentReceiveTimeSamples;
///
/// Cumulative receive time for the sample so far.
///
private int m_receiveTicksInCurrentSamplePeriod;
///
/// The average time taken for each require receive in the last sample.
///
public float AverageReceiveTicksForLastSamplePeriod { get; private set; }
#region PacketDropDebugging
///
/// For debugging purposes only... random number generator for dropping
/// outbound packets.
///
private Random m_dropRandomGenerator;
///
/// For debugging purposes only... parameters for a simplified
/// model of packet loss with bursts, overall drop rate should
/// be roughly 1 - m_dropLengthProbability / (m_dropProbabiliy + m_dropLengthProbability)
/// which is about 1% for parameters 0.0015 and 0.15
///
private double m_dropProbability = 0.0030;
private double m_dropLengthProbability = 0.15;
private bool m_dropState = false;
///
/// For debugging purposes only... parameters to control the time
/// duration over which packet loss bursts can occur, if no packets
/// have been sent for m_dropResetTicks milliseconds, then reset the
/// state of the packet dropper to its default.
///
private int m_dropLastTick = 0;
private int m_dropResetTicks = 500;
///
/// Debugging code used to simulate dropped packets with bursts
///
private bool DropOutgoingPacket()
{
double rnum = m_dropRandomGenerator.NextDouble();
// if the connection has been idle for awhile (more than m_dropResetTicks) then
// reset the state to the default state, don't continue a burst
int curtick = Util.EnvironmentTickCount();
if (Util.EnvironmentTickCountSubtract(curtick, m_dropLastTick) > m_dropResetTicks)
m_dropState = false;
m_dropLastTick = curtick;
// if we are dropping packets, then the probability of dropping
// this packet is the probability that we stay in the burst
if (m_dropState)
{
m_dropState = (rnum < (1.0 - m_dropLengthProbability)) ? true : false;
}
else
{
m_dropState = (rnum < m_dropProbability) ? true : false;
}
return m_dropState;
}
#endregion PacketDropDebugging
///
/// Default constructor
///
/// Local IP address to bind the server to
/// Port to listening for incoming UDP packets on
/// /// Are we to use an object pool to get objects for handing inbound data?
public OpenSimUDPBase(IPAddress bindAddress, int port)
{
m_localBindAddress = bindAddress;
m_udpPort = port;
// for debugging purposes only, initializes the random number generator
// used for simulating packet loss
// m_dropRandomGenerator = new Random();
}
///
/// Start inbound UDP packet handling.
///
/// 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
/// 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
/// 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
public virtual void StartInbound(int recvBufferSize, bool asyncPacketHandling)
{
m_asyncPacketHandling = asyncPacketHandling;
if (!IsRunningInbound)
{
m_log.DebugFormat("[UDPBASE]: Starting inbound UDP loop");
const int SIO_UDP_CONNRESET = -1744830452;
IPEndPoint ipep = new IPEndPoint(m_localBindAddress, m_udpPort);
m_log.DebugFormat(
"[UDPBASE]: Binding UDP listener using internal IP address config {0}:{1}",
ipep.Address, ipep.Port);
m_udpSocket = new Socket(
AddressFamily.InterNetwork,
SocketType.Dgram,
ProtocolType.Udp);
try
{
if (m_udpSocket.Ttl < 128)
{
m_udpSocket.Ttl = 128;
}
}
catch (SocketException)
{
m_log.Debug("[UDPBASE]: Failed to increase default TTL");
}
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");
}
// On at least Mono 3.2.8, multiple UDP sockets can bind to the same port by default. At the moment
// we never want two regions to listen on the same port as they cannot demultiplex each other's messages,
// leading to a confusing bug.
// By default, Windows does not allow two sockets to bind to the same port.
m_udpSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, false);
if (recvBufferSize != 0)
m_udpSocket.ReceiveBufferSize = recvBufferSize;
m_udpSocket.Bind(ipep);
IsRunningInbound = true;
// kick off an async receive. The Start() method will return, the
// actual receives will occur asynchronously and will be caught in
// AsyncEndRecieve().
AsyncBeginReceive();
}
}
///
/// Start outbound UDP packet handling.
///
public virtual void StartOutbound()
{
m_log.DebugFormat("[UDPBASE]: Starting outbound UDP loop");
IsRunningOutbound = true;
}
public virtual void StopInbound()
{
if (IsRunningInbound)
{
m_log.DebugFormat("[UDPBASE]: Stopping inbound UDP loop");
IsRunningInbound = false;
m_udpSocket.Close();
}
}
public virtual void StopOutbound()
{
m_log.DebugFormat("[UDPBASE]: Stopping outbound UDP loop");
IsRunningOutbound = false;
}
public virtual bool EnablePools()
{
if (!UsePools)
{
Pool = new Pool(() => new UDPPacketBuffer(), 500);
UsePools = true;
return true;
}
return false;
}
public virtual bool DisablePools()
{
if (UsePools)
{
UsePools = false;
// We won't null out the pool to avoid a race condition with code that may be in the middle of using it.
return true;
}
return false;
}
private void AsyncBeginReceive()
{
UDPPacketBuffer buf;
// FIXME: Disabled for now as this causes issues with reused packet objects interfering with each other
// on Windows with m_asyncPacketHandling = true, though this has not been seen on Linux.
// Possibly some unexpected issue with fetching UDP data concurrently with multiple threads. Requires more investigation.
// if (UsePools)
// buf = Pool.GetObject();
// else
buf = new UDPPacketBuffer();
if (IsRunningInbound)
{
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 e)
{
m_log.Error(
string.Format("[UDPBASE]: Error processing UDP begin receive {0}. Exception ", UdpReceives), e);
}
catch (Exception e)
{
m_log.Error(
string.Format("[UDPBASE]: Error processing UDP begin receive {0}. Exception ", UdpReceives), e);
}
}
}
private void AsyncEndReceive(IAsyncResult iar)
{
// Asynchronous receive operations will complete here through the call
// to AsyncBeginReceive
if (IsRunningInbound)
{
UdpReceives++;
// Asynchronous mode will start another receive before the
// callback for this packet is even fired. Very parallel :-)
if (m_asyncPacketHandling)
AsyncBeginReceive();
try
{
// get the buffer that was created in AsyncBeginReceive
// this is the received data
UDPPacketBuffer buffer = (UDPPacketBuffer)iar.AsyncState;
int startTick = Util.EnvironmentTickCount();
// 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);
// If more than one thread can be calling AsyncEndReceive() at once (e.g. if m_asyncPacketHandler)
// then a particular stat may be inaccurate due to a race condition. We won't worry about this
// since this should be rare and won't cause a runtime problem.
if (m_currentReceiveTimeSamples >= s_receiveTimeSamples)
{
AverageReceiveTicksForLastSamplePeriod
= (float)m_receiveTicksInCurrentSamplePeriod / s_receiveTimeSamples;
m_receiveTicksInCurrentSamplePeriod = 0;
m_currentReceiveTimeSamples = 0;
}
else
{
m_receiveTicksInCurrentSamplePeriod += Util.EnvironmentTickCountSubtract(startTick);
m_currentReceiveTimeSamples++;
}
}
catch (SocketException se)
{
m_log.Error(
string.Format(
"[UDPBASE]: Error processing UDP end receive {0}, socket error code {1}. Exception ",
UdpReceives, se.ErrorCode),
se);
}
catch (ObjectDisposedException e)
{
m_log.Error(
string.Format("[UDPBASE]: Error processing UDP end receive {0}. Exception ", UdpReceives), e);
}
catch (Exception e)
{
m_log.Error(
string.Format("[UDPBASE]: Error processing UDP end receive {0}. Exception ", UdpReceives), e);
}
finally
{
// if (UsePools)
// Pool.ReturnObject(buffer);
// 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 (IsRunningOutbound)
// {
// This is strictly for debugging purposes to simulate dropped
// packets when testing throttles & retransmission code
// if (DropOutgoingPacket())
// return;
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);
UdpSends++;
}
catch (SocketException) { }
catch (ObjectDisposedException) { }
}
}
}