TNUdpProtocol OnReceive crashing when BeginReceiveFrom

[asinbow]

System.Net.Sockets.SocketException (0x80004005): 远程主机强迫关闭了一个现有的连接。(Chinese. Remote host closed current connection forcibly)
   在(at) System.Net.Sockets.Socket.DoBeginReceiveFrom(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags, EndPoint endPointSnapshot, SocketAddress socketAddress, OverlappedAsyncResult asyncResult)
   在(at) System.Net.Sockets.Socket.BeginReceiveFrom(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags, EndPoint& remoteEP, AsyncCallback callback, Object state)
   在(at) TNet.UdpProtocol.OnReceive(IAsyncResult result) 位置(location) d:\work\repo\warship-hunter-mad\dev\jinggle-server\TNet\TNet.Server\Common\TNUdpProtocol.cs:行号(line) 198
   在(at) System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   在(at) System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   在(at) System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   在(at) System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   在(at) System.Net.ContextAwareResult.Complete(IntPtr userToken)
   在(at) System.Net.Sockets.BaseOverlappedAsyncResult.CompletionPortCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped)
   在(at) System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP)

It crashes when both BeginReceiveFrom and connection closed by remote at the same time.
This issue still exists in 2.0.4.
Maybe should wrap with try-catch.

[ArenMook]

Why are you getting connection-based errors (TCP) on a UDP socket?

[asinbow]

"In UDP land, one way this can occur is when you send a UDP packet to a host, and the remote host doesn't have a listener on that port, and bounces an ICMP host unreachable message in response."

http://stackoverflow.com/questions/7201862/an-existing-connection-was-forcibly-closed-by-the-remote-host

[ArenMook]

Well, I've wrapped it on my end so it will be so in the next update.

[asinbow]

Thanks for your response!
I've also written a test program to easily regenerate the crash.
You can use this code for test.

* Test locally:
*   Just run it.
*   It's very easy to re-generate the crash in this mode.
*
* Test across machines:
*   server:
*     Test.exe 9988
*   client:
*     Test.exe 9988 192.168.x.x
*   It's NOT very easy to re-generate the crash in this mode.

1. using System;
2. using System.Net;
3. using System.Net.Sockets;
4.  
5. namespace Test
6. {
7.     class Program
8.     {
9.         private class AsyncData
10.         {
11.             public int Port;
12.             public Socket Socket;
13.             public EndPoint EndPoint;
14.         }
15.         private static void StartUDPServer(int port)
16.         {
17.             var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
18.             EndPoint endpoint = new IPEndPoint(IPAddress.Any, 0);
19.             socket.Bind(new IPEndPoint(IPAddress.Any, port));
20.             byte[] buffer = new byte[100];
21.             socket.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref endpoint, OnReceivedFrom, new AsyncData()
22.                 {
23.                     Port = port,
24.                     Socket = socket,
25.                     EndPoint = endpoint,
26.                 });
27.         }
28.  
29.         private static void OnReceivedFrom(IAsyncResult result)
30.         {
31.             var data = (AsyncData)result.AsyncState;
32.             int bytes = data.Socket.EndReceiveFrom(result, ref data.EndPoint);
33.  
34.             byte[] buffer = new byte[100];
35.             data.Socket.BeginSendTo(buffer, 0, buffer.Length, SocketFlags.None, data.EndPoint, OnServerSentTo, data); // KEY_POINT-I: send anything back
36.             data.Socket.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref data.EndPoint, OnReceivedFrom, data);
37.         }
38.         private static void OnServerSentTo(IAsyncResult result)
39.         {
40.             var data = (AsyncData)result.AsyncState;
41.             int bytes = data.Socket.EndSendTo(result);
42.             //Console.WriteLine("sent {0} back", bytes);
43.         }
44.         private static void StartUDPClient(EndPoint server)
45.         {
46.             var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
47.             byte[] buffer = new byte[100];
48.             socket.BeginSendTo(buffer, 0, buffer.Length, SocketFlags.None, server, OnClientSentTo, new AsyncData()
49.                 {
50.                     Port = 0,
51.                     Socket = socket,
52.                     EndPoint = server,
53.                 });
54.         }
55.         private static void OnClientSentTo(IAsyncResult result)
56.         {
57.             var data = (AsyncData)result.AsyncState;
58.             int bytes = data.Socket.EndSendTo(result);
59.  
60.             data.Socket.Close(); // KEY_POINT-II: close client it immediately
61.  
62.             StartUDPClient(data.EndPoint);
63.         }
64.  
65.  
66.         /**
67.          *
68.          * Test locally:
69.          *   Just run it.
70.          *   It's very easy to re-generate the crash in this mode.
71.          *
72.          
73.          * Test across machines:
74.          *   server:
75.          *     Test.exe 9988
76.          *   client:
77.          *     Test.exe 9988 192.168.x.x
78.          *   It's NOT very easy to re-generate the crash in this mode.
79.          *
80.         */
81.         static void Main(string[] args)
82.         {
83.             bool localTest = true; // both server and client locally
84.  
85.             EndPoint server = null;
86.             int port = 9988;
87.             if (args.Length > 0) // first argument as port
88.             {
89.                 localTest = false;
90.                 port = int.Parse(args[0]);
91.             }
92.  
93.             if (args.Length > 1) // if client, second argument as server address
94.             {
95.                 foreach (var address in Dns.GetHostAddresses(args[1]))
96.                 {
97.                     if (address.AddressFamily  == AddressFamily.InterNetwork)
98.                     {
99.                         server = new IPEndPoint(address, port);
100.                     }
101.                 }
102.             }
103.  
104.             if (localTest)
105.             {
106.                 server = new IPEndPoint(IPAddress.Loopback, port);
107.                 StartUDPServer(port);
108.                 StartUDPClient(server);
109.             }
110.             else if (server == null)
111.             {
112.                 StartUDPServer(port);
113.             }
114.             else
115.             {
116.                 StartUDPClient(server);
117.             }
118.  
119.             System.Console.ReadLine();
120.         }
121.     }
122. }
123.  
124.  

Thanks again!