From b82d946af37d19cf19033ca63ff8be051bfee361 Mon Sep 17 00:00:00 2001
From: Darren Horrocks <killallthehumans@gmail.com>
Date: Sat, 21 Oct 2023 00:09:43 +0100
Subject: [PATCH] fix threading/concurrency issue in TCP connection

---
 bzTorrent/IO/PeerWireTCPConnection.cs | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/bzTorrent/IO/PeerWireTCPConnection.cs b/bzTorrent/IO/PeerWireTCPConnection.cs
index c4790b3..8a0963a 100644
--- a/bzTorrent/IO/PeerWireTCPConnection.cs
+++ b/bzTorrent/IO/PeerWireTCPConnection.cs
@@ -35,6 +35,7 @@ DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 using System.Text;
 using System;
 using System.Net;
+using System.Collections.Concurrent;
 
 namespace bzTorrent.IO
 {
@@ -45,8 +46,8 @@ public class PeerWireTCPConnection : IPeerConnection
 		private byte[] currentPacketBuffer = null;
 		private const int socketBufferSize = 16 * 1024;
 		private readonly byte[] socketBuffer = new byte[socketBufferSize];
-		private readonly Queue<PeerWirePacket> receiveQueue = new();
-		private readonly Queue<PeerWirePacket> sendQueue = new();
+		private readonly ConcurrentQueue<PeerWirePacket> receiveQueue = new();
+		private readonly ConcurrentQueue<PeerWirePacket> sendQueue = new();
 		private PeerClientHandshake incomingHandshake = null;
 
 		public int Timeout
@@ -135,10 +136,12 @@ public bool Process()
 				socket.BeginReceive(socketBuffer, 0, socketBufferSize, SocketFlags.None, ReceiveCallback, this);
 			}
 
-			while(sendQueue.Count > 0)
+			while (sendQueue.Count > 0)
 			{
-				var packet = sendQueue.Dequeue();
-				socket.Send(packet.GetBytes());
+				if (sendQueue.TryDequeue(out var packet)) 
+				{
+					socket.Send(packet.GetBytes());
+				}
 			}
 
 			return Connected;
@@ -151,9 +154,9 @@ public void Send(PeerWirePacket packet)
 
 		public PeerWirePacket Receive()
 		{
-			if (receiveQueue.Count > 0)
+			if (receiveQueue.Count > 0 && receiveQueue.TryDequeue(out var packet))
 			{
-				return receiveQueue.Dequeue();
+				return packet;
 			}
 
 			return null;