如何设置Socket.ConnectAsync的超时时间？

Question

我一直在阅读有关如何检查 LAN 上特定端口上的所有侦听服务器的信息，最后我编写了一些代码，它可以按我想要的方式工作。
我正在使用 System.Threading.Tasks.Parallel 尽快连接到所有 254 个 IP 地址，例如
：192.168.1。1 - 192.168.1。第254章

我需要的是为这些连接尝试设置超时，因为失败时需要大约 15-20 秒才能打印：“连接失败”..那么我该怎么做？

这是客户端代码：

static void Main(string[] args)
    {
        Console.WriteLine("Connecting to IP addresses has started. \n");

        Parallel.For(1, 255, i =>
        {
            Connect("192.168.1." + i);
        });
        Console.ReadLine();
    }

    private static void Connect(string ipAdd)
    {
        Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        SocketAsyncEventArgs e = new SocketAsyncEventArgs();
        IPEndPoint ipEnd = new IPEndPoint(IPAddress.Parse(ipAdd), 9990);
        e.RemoteEndPoint = ipEnd;
        e.UserToken = s;
        e.Completed += new EventHandler<SocketAsyncEventArgs>(e_Completed);
        Console.WriteLine("Trying to connect to : " + ipEnd);
        s.ConnectAsync(e);
    }
    private static void e_Completed(object sender, SocketAsyncEventArgs e)
    {
        if (e.ConnectSocket != null)
        {
            StreamReader sr = new StreamReader(new NetworkStream(e.ConnectSocket));
            Console.WriteLine("Connection Established : " + e.RemoteEndPoint + " PC NAME : " + sr.ReadLine());
        }
        else
        {
            Console.WriteLine("Connection Failed : " + e.RemoteEndPoint);
        }
    }

服务器代码：

static void Main(string[] args)
    {
        Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        IPEndPoint ep = new IPEndPoint(IPAddress.Any,9990);
        server.Bind(ep);
        server.Listen(100);
        Socket client = server.Accept();
        NetworkStream stream = new NetworkStream(client);
        StreamWriter sw = new StreamWriter(stream)
        sw.WriteLine(System.Environment.MachineName);
        sw.Flush();
        sw.Dispose();
        stream.Dispose();
        client.Dispose();
        server.Dispose();
    }

如果有任何提示或注意可以让它变得更好，请告诉我。我正在使用 [.Net 4.0] 套接字 TCP。

Answer 1

我已经想出了一个解决办法。首先将所有创建的套接字添加到SocketAsyncEventArgs类型或Socket类型
的列表中， 然后使用 System.Timers.Timer 关闭所有挂起的连接以及在计时器滴答（5 秒后）后连接的连接。（计时器。间隔 = 5000）。

客户端代码：

   //I've changed my console application to Winform
   public ServerDiscovery()
    {
        InitializeComponent();
        timer.Elapsed += timer_tick;
    }

    System.Timers.Timer timer = new System.Timers.Timer(5000);
    List<SocketAsyncEventArgs> list = new List<SocketAsyncEventArgs>();

    private void btnRefresh_Click(object sender, EventArgs e)
    {
        timer.Start();
        Parallel.For(1, 255, (i, loopState) =>
        {
            ConnectTo("192.168.1." + i);
        });
    }

    private void ConnectTo(string ipAdd)
    {
        Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        SocketAsyncEventArgs e = new SocketAsyncEventArgs();
        e.RemoteEndPoint = new IPEndPoint(IPAddress.Parse(ipAdd), 9990);
        e.UserToken = s;
        e.Completed += new EventHandler<SocketAsyncEventArgs>(e_Completed);
        list.Add(e);      // Add to a list so we dispose all the sockets when the timer ticks.
        s.ConnectAsync(e);
    }

    private void e_Completed(object sender, SocketAsyncEventArgs e)
    {
        if (e.ConnectSocket != null)     //if there's a connection Add its info to a listview
        {
            StreamReader sr = new StreamReader(new NetworkStream(e.ConnectSocket));
            ListViewItem item = new ListViewItem();
            item.Text = sr.ReadLine();
            item.SubItems.Add(((IPEndPoint)e.RemoteEndPoint).Address.ToString());
            item.SubItems.Add("Online");
            AddServer(item);
        }
    }

    delegate void AddItem(ListViewItem item);
    private void AddServer(ListViewItem item)
    {
        if (InvokeRequired)
        {
            Invoke(new AddItem(AddServer), item);
            return;
        }
        listServer.Items.Add(item);
    }

    private void timer_tick(object sender, EventArgs e)
    {
        timer.Stop();
        foreach (var s in list)
        {
            ((Socket)s.UserToken).Dispose();     //disposing all sockets that's pending or connected.
        }
    }