UDP服务器中接收数据包的连接重置

Question

我正在研究一个服务器应用程序(C#,.NET 4.0),它需要每秒处理数千个UDP数据包.所以我决定SocketAsyncEventArg实现服务器.

我面临的问题是我的实现只收到一个数据包然后我得到"ConnectionReset"错误(我从未想过我会得到这个错误,因为UDP是无连接的).这是我的测试实现:

using System;
using System.Net;
using System.Net.Sockets;

static class Program
{
    static void Main(string[] args)
    {
        UdpEchoServer.Start();

        while (true)
        {
            Console.ReadLine();
            SendPacket();
        }
    }

    static void SendPacket()
    {
        Console.WriteLine("SendPacket");
        var c = new UdpClient();
        c.Send(new byte[5], 5, new IPEndPoint(IPAddress.Parse("127.0.0.1"), 445));
        c.Close();
    }
}

static class UdpEchoServer
{
    static Socket mSocket;
    static byte[] mBuffer;
    static SocketAsyncEventArgs mRxArgs, mTxArgs;
    static IPEndPoint mAnyEndPoint, mLocalEndPoint;

    public static void Start()
    {
        mAnyEndPoint = new IPEndPoint(IPAddress.Any, 0);
        mLocalEndPoint = new IPEndPoint(IPAddress.Any, 445);

        mBuffer = new byte[1024];

        mRxArgs = new SocketAsyncEventArgs();
        mTxArgs = new SocketAsyncEventArgs();

        mRxArgs.Completed += ReceiveComplete;
        mTxArgs.Completed += SendComplete;

        mSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        mSocket.Bind(mLocalEndPoint);
        ReceiveNext();
    }

    static void ReceiveNext()
    {
        Console.WriteLine("ReceiveNext");

        mRxArgs.RemoteEndPoint = mAnyEndPoint;
        mRxArgs.SetBuffer(mBuffer, 0, mBuffer.Length);

        if (!mSocket.ReceiveFromAsync(mRxArgs))
            Console.WriteLine("Error in ReceiveNext: " + mRxArgs.SocketError);
    }

    static void ReceiveComplete(object sender, SocketAsyncEventArgs e)
    {
        Console.WriteLine("Receive Complete: " + mRxArgs.SocketError);

        if (mRxArgs.SocketError != SocketError.Success)
            return;

        mTxArgs.SetBuffer(mBuffer, 0, mRxArgs.BytesTransferred);
        mTxArgs.RemoteEndPoint = mRxArgs.RemoteEndPoint;

        Console.WriteLine("Sending reply packet");

        if (!mSocket.SendToAsync(mTxArgs))
            Console.WriteLine("Error in ReceiveComplete: " + mRxArgs.SocketError);
    }

    static void SendComplete(object sender, SocketAsyncEventArgs e)
    {
        Console.WriteLine("Send Complete: " + mTxArgs.SocketError);

        if (mTxArgs.SocketError != SocketError.Success)
            return;

        ReceiveNext();
    }
}

很抱歉长代码,但它非常简单.我等待一个数据包,回复远程终点,然后等待下一个.这是输出:

ReceiveNext

SendPacket
Receive Complete: Success
Sending reply packet
Send Complete: Success
ReceiveNext
Error in ReceiveNext: ConnectionReset

请问您能否在上面的代码片段中提出错误建议？

Answer 1

使用UDP套接字会发生这种情况.您需要做的就是在绑定之前更改套接字操作模式.在您的Start方法中使用此代码.

mSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

const int SIO_UDP_CONNRESET = -1744830452;
byte[] inValue = new byte[] {0};
byte[] outValue = new byte[] {0};
mSocket.IOControl(SIO_UDP_CONNRESET, inValue, outValue);

mSocket.Bind(mLocalEndPoint);