c# - 重用 UdpClient 与处置它

Question

我正在创建一个聊天应用程序，其中用户位于路由器 (NAT) 后面。所以主要问题是向这些客户发送消息。服务器接收消息没有问题。

这是我的协议(protocol)(规则):

UdpServer监听来自 client A 的 udp 数据包

Server从 client A 接收数据包并回复一个数据包以打开 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)我现在反转客户端和服务器，因为 NAT 已打开 .这是因为 client A总是可以通过tcp向服务器发送消息。

如果 Server看到 client A不回复它不断发送它标记的数据包client A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;
}

监听新客户端(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 开放的线程

// 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

一切正常但是为每个请求创建一个新的套接字(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。当我尝试重用更新其端点的 udp 客户端时，我得到一个异常。我经常需要给 Client A发消息或者也许 Client Z这就是为什么我存储它的端点以知道如何到达它。 如何重用 udpClient 更新其端点，以便能够访问我感兴趣的客户端？

Answer 1

我应该再次推荐使用 Socket s 直接，它给你很大的灵 active 。查看以下示例，该示例使用一个套接字进行发送和接收的 UDP 连接:

    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();
    }