这是我的协议（规则）：

UdpServer侦听来自client A
Server从client A接收数据包并回复数据包以打开NAT
Server现在成为客户端（服务器不断向client A发送数据包，客户端回复服务器通知它收到了他的消息）我反转客户端和服务器现在NAT已经打开。这是因为client A始终可以通过tcp向服务器发送消息。
如果Server发现client A没有回复其经常发送的数据包，则会将client A标记为已断开连接并停止发送数据包。

这是代码

// class that holds infor about client
class ClientBehindNat
{
     public IPEndPoint EndpointListening;
     public string Id;
}

侦听新客户端（连接）的线程：

while(true)
{
    IPEndPoint ep = new IPEndPoint(IPAddress.Any, 1234);
    // create a new udpServer
    using(var udpServer = new UdpClient())
    {
        // allow reusing port 1234
        udpServer.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
        // wait to receive data
        var data = udpServer.Receive(ref ep);

        // analyze data make sure it is reliable....

        // maybe data is a reply from a client 
        if(data.IsReply())
        {
             // mark that client replied
             // ....
             continue;
        }
        else
        {
            // save new client
            ConnectedClients.Add(new ClientBehindNat(){EndpointListening=ep});
        }

        udpServer.Connect(ep);
        udpServer.Send( // data notifying client that we got his message)

    }
}

不断向客户端发送udp数据包以保持nat打开的线程

// send packets every 15 seconds in order to leave nat open
timer.elapsed += (a,b)=> {

    foreach (var c in connectedClients)
    {
        // create a copy of udp server so that client can get our response
        using (var copySocket = new UdpClient())
        {
            // allow reusing port 1234
            copySocket.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
            copySocket.Client.Bind(new IPEndPoint(IPAddress.Any, 1234));
            // log that we will send this request
            // Requests[someId] = ....

            // send it
            copySocket.Send(someData, someData.Length, c.EndpointListening);

            // first thread should be responsible for receiving this response

            // dispose this client                            
        }          
    }
}

这是问题

一切都很好但是每个请求创建一个新的Socket（UdpClient）是不是很糟糕？如果我收到100个请求，我会创建100个新套接字并处理所有这些。当我尝试重用udp客户端更新其端点时，我得到一个例外。我经常需要向Client A或Client Z发送消息，这就是为什么我存储其端点以了解如何到达它。 如何重用udpClient更新其端点，以便我能够访问我感兴趣的客户端？

Answer 1

我应该再次建议直接使用Socket s，它会给你很大的灵活性。请查看以下示例，该示例使用一个套接字进行UDP连接以进行发送和接收：

    private static readonly List<EndPoint> clients = new List<EndPoint>();
    private static readonly SocketAsyncEventArgs receiveEventArgs = new SocketAsyncEventArgs();
    private static Socket socket;

    private static void Main(string[] args)
    {
        receiveEventArgs.Completed += OnReceive;
        socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
        socket.Bind(new IPEndPoint(IPAddress.Any, 6000));
        Receive();

        while (true)
        {
            Thread.Sleep(3000);
            lock (clients)
            {
                foreach (var endPoint in clients)
                    socket.SendTo(Encoding.ASCII.GetBytes("PING"), endPoint);
            }
        }
    }

    private static void Receive()
    {
        receiveEventArgs.SetBuffer(new byte[256], 0, 256);
        receiveEventArgs.RemoteEndPoint = new IPEndPoint(IPAddress.Any, 6000);
        socket.ReceiveFromAsync(receiveEventArgs);
    }

    private static void OnReceive(object sender, SocketAsyncEventArgs e)
    {
        if (e.BytesTransferred > 0)
        {
            // Is reply?
            var isReply = true/false;
            if (isReply)
            {
                // Do domething
            }
            else
                lock (clients)
                {
                    clients.Add(e.RemoteEndPoint);
                }
        }
        else
        {
            lock (clients)
            {
                clients.Remove(e.RemoteEndPoint);
            }
        }
        Receive();
    }

Answer 2

发现问题。当我回复客户时，我得到了回复，我正在这样做：

udpServer.Connect(ep); // <---------------- this was the problem
udpServer.Send(someData);

如果我从未连接并使用@Sourush声明的SneTo方法，它可以让我继续监听数据包。所以现在我有：

udpServer.Client.SentTo(data, ep)

重用UdpClient vs处理它

这是我的协议（规则）：

这是代码

这是问题

2 个答案: