From 90d69a05233206e1bce5896405bd34545bcd6b40 Mon Sep 17 00:00:00 2001
From: Justin Clarke Casey
Date: Fri, 17 Oct 2008 20:14:31 +0000
Subject: * close two potential race conditions where a new asynchronous UDP
recieve could overwrite an existing endpoint that had not yet been used by
the previous thread * in practice these race conditions were probably pretty
rare
---
.../Region/ClientStack/LindenUDP/LLUDPServer.cs | 122 +++++++++------------
1 file changed, 53 insertions(+), 69 deletions(-)
(limited to 'OpenSim')
diff --git a/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs b/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
index 26a77e4..01a4dd6 100644
--- a/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
+++ b/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
@@ -58,10 +58,11 @@ namespace OpenSim.Region.ClientStack.LindenUDP
protected byte[] ZeroBuffer = new byte[8192];
///
- /// The endpoint of a sender of a particular packet. The port is changed by the various socket receive methods
+ /// This is an endpoint that is reused where we don't need to protect the information from potentially
+ /// being stomped on by other threads.
///
protected EndPoint reusedEpSender = new IPEndPoint(IPAddress.Any, 0);
- protected EndPoint reusedEpProxy;
+
protected int proxyPortOffset;
protected AsyncCallback ReceivedData;
@@ -178,11 +179,11 @@ namespace OpenSim.Region.ClientStack.LindenUDP
Packet packet = null;
int numBytes = 1;
bool ok = false;
- reusedEpSender = new IPEndPoint(IPAddress.Any, 0);
+ EndPoint epSender = new IPEndPoint(IPAddress.Any, 0);
try
{
- numBytes = m_socket.EndReceiveFrom(result, ref reusedEpSender);
+ numBytes = m_socket.EndReceiveFrom(result, ref epSender);
ok = true;
}
catch (SocketException e)
@@ -218,12 +219,6 @@ namespace OpenSim.Region.ClientStack.LindenUDP
for (z = numBytes ; z < RecvBuffer.Length ; z++)
RecvBuffer[z] = 0;
- reusedEpProxy = reusedEpSender;
- if (proxyPortOffset != 0)
- {
- reusedEpSender = ProxyCodec.DecodeProxyMessage(RecvBuffer, ref numBytes);
- }
-
int packetEnd = numBytes - 1;
try
@@ -242,30 +237,48 @@ namespace OpenSim.Region.ClientStack.LindenUDP
{
m_log.Debug("[CLIENT]: " + e);
}
+ }
+
+ EndPoint epProxy = null;
+
+ // If we've received a use circuit packet, then we need to decode an endpoint proxy, if one exists, before
+ // allowing the RecvBuffer to be overwritten by the next packet.
+ if (packet.Type == PacketType.UseCircuitCode)
+ {
+ epProxy = epSender;
+ if (proxyPortOffset != 0)
+ {
+ epSender = ProxyCodec.DecodeProxyMessage(RecvBuffer, ref numBytes);
+ }
}
-
- BeginReceive();
+
+ BeginReceive();
if (packet != null)
- ProcessInPacket(packet);
+ {
+ if (packet.Type == PacketType.UseCircuitCode)
+ AddNewClient((UseCircuitCodePacket)packet, epSender, epProxy);
+ else
+ ProcessInPacket(packet, epSender);
+ }
}
///
- /// Process a successfully received packet. We pass the packet on to the LLPacketServer
- /// except in the case that the packet is UseCircuitCode. In that case we set up the circuit code instead.
+ /// Process a successfully received packet.
///
///
- protected virtual void ProcessInPacket(Packet packet)
+ ///
+ protected virtual void ProcessInPacket(Packet packet, EndPoint epSender)
{
try
{
// do we already have a circuit for this endpoint
uint circuit;
-
bool ret;
+
lock (clientCircuits)
{
- ret = clientCircuits.TryGetValue(reusedEpSender, out circuit);
+ ret = clientCircuits.TryGetValue(epSender, out circuit);
}
if (ret)
@@ -275,21 +288,6 @@ namespace OpenSim.Region.ClientStack.LindenUDP
m_packetServer.InPacket(circuit, packet);
}
- else if (packet.Type == PacketType.UseCircuitCode)
- {
- UseCircuitCodePacket p = (UseCircuitCodePacket)packet;
-
- AddNewClient(p);
-
- // Ack the first UseCircuitCode packet
- PacketAckPacket ack_it = (PacketAckPacket)PacketPool.Instance.GetPacket(PacketType.PacketAck);
- // TODO: don't create new blocks if recycling an old packet
- ack_it.Packets = new PacketAckPacket.PacketsBlock[1];
- ack_it.Packets[0] = new PacketAckPacket.PacketsBlock();
- ack_it.Packets[0].ID = packet.Header.Sequence;
- ack_it.Header.Reliable = false;
- SendPacketTo(ack_it.ToBytes(), ack_it.ToBytes().Length, SocketFlags.None, p.CircuitCode.Code);
- }
}
catch (Exception e)
{
@@ -319,7 +317,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
}
catch (Exception a)
{
- m_log.Info("[UDPSERVER]: " + a);
+ m_log.Error("[UDPSERVER]: " + a);
}
try
@@ -356,61 +354,47 @@ namespace OpenSim.Region.ClientStack.LindenUDP
/// Add a new client circuit.
///
///
- protected virtual void AddNewClient(UseCircuitCodePacket useCircuit)
+ ///
+ ///
+ protected virtual void AddNewClient(UseCircuitCodePacket useCircuit, EndPoint epSender, EndPoint epProxy)
{
//Slave regions don't accept new clients
if (m_localScene.Region_Status != RegionStatus.SlaveScene)
{
- m_log.DebugFormat(
- "[CLIENT]: Adding new circuit for agent {0}, circuit code {1}",
- useCircuit.CircuitCode.ID, useCircuit.CircuitCode.Code);
-
- // Copy the current reusedEpSender and reusedEpProxy to store in the maps and hashes,
- // since the reused ones will change on the next packet receipt.
- IPEndPoint reusedIpEpSender = (IPEndPoint)reusedEpSender;
- EndPoint epSender = new IPEndPoint(reusedIpEpSender.Address, reusedIpEpSender.Port);
-
- IPEndPoint reusedIpEpPorxy = (IPEndPoint)reusedEpProxy;
- EndPoint epProxy = new IPEndPoint(reusedIpEpPorxy.Address, reusedIpEpPorxy.Port);
-
lock (clientCircuits)
{
- if (!clientCircuits.ContainsKey(epSender))
- {
- clientCircuits.Add(epSender, useCircuit.CircuitCode.Code);
- }
- else
+ if (!clientCircuits.ContainsKey(epSender))
{
- m_log.Error(
- "[CLIENT]: clientCircuits already contains entry for user "
- + useCircuit.CircuitCode.Code + ". NOT adding.");
+ m_log.DebugFormat(
+ "[CLIENT]: Adding new circuit for agent {0}, circuit code {1}",
+ useCircuit.CircuitCode.ID, useCircuit.CircuitCode.Code);
+
+ clientCircuits.Add(epSender, useCircuit.CircuitCode.Code);
}
}
// This doesn't need locking as it's synchronized data
if (!clientCircuits_reverse.ContainsKey(useCircuit.CircuitCode.Code))
clientCircuits_reverse.Add(useCircuit.CircuitCode.Code, epSender);
- else
- m_log.Error(
- "[CLIENT]: clientCurcuits_reverse already contains entry for user "
- + useCircuit.CircuitCode.Code + ". NOT adding.");
lock (proxyCircuits)
{
if (!proxyCircuits.ContainsKey(useCircuit.CircuitCode.Code))
proxyCircuits.Add(useCircuit.CircuitCode.Code, epProxy);
- else
- m_log.Error(
- "[CLIENT]: proxyCircuits already contains entry for user "
- + useCircuit.CircuitCode.Code + ". NOT adding.");
}
- if (!PacketServer.AddNewClient(epSender, useCircuit, m_assetCache, m_circuitManager, epProxy))
- m_log.ErrorFormat(
- "[CLIENT]: A circuit already existed for agent {0}, circuit {1}",
- useCircuit.CircuitCode.ID, useCircuit.CircuitCode.Code);
- }
-
+ PacketServer.AddNewClient(epSender, useCircuit, m_assetCache, m_circuitManager, epProxy);
+ }
+
+ // Ack the UseCircuitCode packet
+ PacketAckPacket ack_it = (PacketAckPacket)PacketPool.Instance.GetPacket(PacketType.PacketAck);
+ // TODO: don't create new blocks if recycling an old packet
+ ack_it.Packets = new PacketAckPacket.PacketsBlock[1];
+ ack_it.Packets[0] = new PacketAckPacket.PacketsBlock();
+ ack_it.Packets[0].ID = useCircuit.Header.Sequence;
+ ack_it.Header.Reliable = false;
+ SendPacketTo(ack_it.ToBytes(), ack_it.ToBytes().Length, SocketFlags.None, useCircuit.CircuitCode.Code);
+
PacketPool.Instance.ReturnPacket(useCircuit);
}
--
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