1 files changed, 89 insertions, 6 deletions

diff --git a/OpenSim/Region/ClientStack/Linden/UDP/OpenSimUDPBase.cs b/OpenSim/Region/ClientStack/Linden/UDP/OpenSimUDPBase.cs
index 0030dee..7171974 100644
--- a/OpenSim/Region/ClientStack/Linden/UDP/OpenSimUDPBase.cs
+++ b/OpenSim/Region/ClientStack/Linden/UDP/OpenSimUDPBase.cs
@@ -107,6 +107,62 @@ namespace OpenMetaverse
         /// </summary>
         public float AverageReceiveTicksForLastSamplePeriod { get; private set; }
 
+        #region PacketDropDebugging
+        /// <summary>
+        /// For debugging purposes only... random number generator for dropping
+        /// outbound packets.
+        /// </summary>
+        private Random m_dropRandomGenerator = new Random();
+        
+        /// <summary>
+        /// 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
+        /// </summary>
+        private double m_dropProbability = 0.0030;
+        private double m_dropLengthProbability = 0.15;
+        private bool m_dropState = false;
+
+        /// <summary>
+        /// 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.
+        /// </summary>
+        private int m_dropLastTick = 0;
+        private int m_dropResetTicks = 500;
+        
+        /// <summary>
+        /// Debugging code used to simulate dropped packets with bursts
+        /// </summary>
+        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
+
         /// <summary>
         /// Default constructor
         /// </summary>
@@ -117,6 +173,10 @@ namespace OpenMetaverse
         {
             m_localBindAddress = bindAddress;
             m_udpPort = port;
+
+            // for debugging purposes only, initializes the random number generator
+            // used for simulating packet loss
+            // m_dropRandomGenerator = new Random();
         }
 
         /// <summary>
@@ -135,7 +195,7 @@ namespace OpenMetaverse
         /// 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 StartInbound(int recvBufferSize, bool asyncPacketHandling)
+        public virtual void StartInbound(int recvBufferSize, bool asyncPacketHandling)
         {
             m_asyncPacketHandling = asyncPacketHandling;
 
@@ -158,6 +218,17 @@ namespace OpenMetaverse
 
                 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);
@@ -168,6 +239,12 @@ namespace OpenMetaverse
                     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;
 
@@ -185,14 +262,14 @@ namespace OpenMetaverse
         /// <summary>
         /// Start outbound UDP packet handling.
         /// </summary>
-        public void StartOutbound()
+        public virtual void StartOutbound()
         {
             m_log.DebugFormat("[UDPBASE]: Starting outbound UDP loop");
 
             IsRunningOutbound = true;
         }
 
-        public void StopInbound()
+        public virtual void StopInbound()
         {
             if (IsRunningInbound)
             {
@@ -203,14 +280,14 @@ namespace OpenMetaverse
             }
         }
 
-        public void StopOutbound()
+        public virtual void StopOutbound()
         {
             m_log.DebugFormat("[UDPBASE]: Stopping outbound UDP loop");
 
             IsRunningOutbound = false;
         }
 
-        protected virtual bool EnablePools()
+        public virtual bool EnablePools()
         {
             if (!UsePools)
             {
@@ -224,7 +301,7 @@ namespace OpenMetaverse
             return false;
         }
 
-        protected virtual bool DisablePools()
+        public virtual bool DisablePools()
         {
             if (UsePools)
             {
@@ -389,6 +466,12 @@ namespace OpenMetaverse
         {
 //            if (IsRunningOutbound)
 //            {
+
+                // This is strictly for debugging purposes to simulate dropped
+                // packets when testing throttles & retransmission code
+                // if (DropOutgoingPacket())
+                //     return;
+            
                 try
                 {
                     m_udpSocket.BeginSendTo(