c# - TcpServer - 发送和接收数据

Question

我不得不为工作中的一个项目编写一个 TCP 服务器，我在谷歌上搜索了如何编写。我有一个 MSDN回答并设法让它工作，但我不知道如何让数据能够来回接收。 socket 的连接时间最多不会超过 30 秒(因为我的老板不希望这里的计算机上的 socket 保持打开状态)。此类的目标是在我的主程序中为我提供一种快速方法来检索有关计算机及其用户的数据。

根据命名空间的命名，你大概可以猜到它是给计算机实验室用的。

namespace LabAssist.Server.Common.Objects {
    using Atlantis.Net.Sockets;

    using LabAssist.Server.Common.Data;

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Net;
    using System.Net.Sockets;
    using System.Text;
    using System.Windows.Forms;

    public class TcpServer {

        #region Constructor(s)

        public TcpServer(IPEndPoint endPoint) {
            RemoteEndPoint = endPoint;
            Host = new Socket(RemoteEndPoint.Address.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
        }

        public TcpServer(String hostNameOrIpAddress, Int32 port) {
            RemoteEndPoint = new IPEndPoint(Dns.GetHostEntry(hostNameOrIpAddress).AddressList[0], port);
            Host = new Socket(RemoteEndPoint.Address.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
        }

        public TcpServer(Int32 port) {
            RemoteEndPoint = new IPEndPoint(Dns.GetHostEntry(Dns.GetHostName()).AddressList[0], port);
            Host = new Socket(RemoteEndPoint.Address.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
        }

        #endregion

        #region Fields

        private Boolean m_IsBound = false;
        private List<Socket> m_Connections = new List<Socket>(50); // allow 50 sockets 
        private static System.Threading.ManualResetEvent AllDone = new System.Threading.ManualResetEvent(false);

        #endregion

        #region Properties

        private Int32 m_Backlog = 32;
        /// <summary>
        ///     Gets or sets the number of connections the host can accept at any given point
        /// </summary>
        public Int32 Backlog {
            set {
                m_Backlog = value;
            }
            get {
                return m_Backlog;
            }
        }

        private Socket m_Host = null;
        /// <summary>
        ///     Gets or sets the host master socket
        /// </summary>
        public Socket Host {
            private set {
                m_Host = value;
            }
            get {
                return m_Host;
            }
        }

        private Int32 m_Port = 1337;
        /// <summary>
        ///     Gets or sets the binding port for the server
        /// </summary>
        public Int32 Port {
            set {
                m_Port = value;
            }
            get {
                return m_Port;
            }
        }

        private IPEndPoint m_EndPoint = null;
        /// <summary>
        ///     Gets or sets the binding address to be used when binding the socket
        /// </summary>
        public IPEndPoint RemoteEndPoint {
            private set {
                m_EndPoint = value;
            }
            get {               // follows a singleton pattern with a private-setter.
                if (m_EndPoint == null) {
                    RemoteEndPoint = new IPEndPoint(Dns.GetHostEntry(Dns.GetHostName()).AddressList[0], Port);
                }

                return m_EndPoint;
            }
        }

        #endregion

        #region Methods

        private void AcceptCallback(IAsyncResult ar) {
            Socket client = ((Socket)ar.AsyncState);
            Socket handler = client.EndAccept(ar);
            m_Connections.Add(handler);

            AllDone.Set();

            Console.WriteLine("Client accepted.\t Remote address and port : {0}", handler.RemoteEndPoint.ToString());

            Byte[] buf = Encoding.ASCII.GetBytes("hello world. This is my first TCP Server >:)");
            Int32 ret = 0;
            Boolean ext = false;
            //try-catch temporary until sending is figured out. ><
            try {
                ret = client.Send(buf, buf.Length, SocketFlags.None);
            } catch (Exception ex) {
                ext = true;
                ConsoleColor c = Console.ForegroundColor;
                Console.ForegroundColor = ConsoleColor.Yellow;
                Console.WriteLine(ex.ToString());
                Console.ForegroundColor = c;
            }
            // error check for debugging
            if (ret > 0) {
                Console.WriteLine("Sent -> {0}", Encoding.ASCII.GetString(buf, 0, buf.Length));
            } else {
                if (ext) {
                    ConsoleColor c = Console.ForegroundColor;
                    Console.ForegroundColor = ConsoleColor.Red;
                    Console.WriteLine("Caught an exception");
                    Console.ForegroundColor = c;
                }
                Console.WriteLine("Failed to send welcome packet to client.");
            }

            State state = new State();
            state.WorkSocket = handler;
            handler.BeginReceive(state.Buffer, 0, State.BufferSize, 0, new AsyncCallback(ReceiveDataCallback), state);
        }

        /// <summary>
        ///     Intialises the socket to listen and begins to accept connections
        /// </summary>
        /// <returns></returns>
        public void Initialise() {
            Host.Bind(RemoteEndPoint);

            Console.WriteLine("Local address and port : {0}", RemoteEndPoint.ToString());

            m_IsBound = true;
            Host.Listen(Backlog);
            try {
                while (true) {
                    AllDone.Reset();

                    Console.WriteLine("Awaiting{0} client connection...", (m_Connections.Count > 0 ? " another" : ""));

                    Host.BeginAccept(new AsyncCallback(AcceptCallback), Host);

                    AllDone.WaitOne();

                    Application.DoEvents();
                }
            } catch (Exception e) {
                Log.HandledException(e);
            }
        }

        private void ReceiveDataCallback(IAsyncResult ar) {
            State state = ((State)ar.AsyncState);
            Socket handler = state.WorkSocket;

            if (!handler.IsConnected()) {
                return;
            }

            Int32 read = handler.EndReceive(ar);

            if (read > 0) {
                state.DataReceived.Append(Encoding.ASCII.GetString(state.Buffer, 0, read));
                handler.BeginReceive(state.Buffer, 0, State.BufferSize, SocketFlags.None, new AsyncCallback(ReceiveDataCallback), state);
            } else {
                if (state.DataReceived.Length > 1) {
                    String content = state.DataReceived.ToString();
                    Console.WriteLine("Read {0} bytes from socket.\n Data: {1}", content.Length, content);
                }
                handler.Close();
            }
        }

        #endregion
    }
}

目前，我正在尝试让一个简单的版本工作，客户端在连接时从服务器接收一个数据包，上面写着“hello world from the net!”之类的内容。我不断收到一些奇怪的异常。上面的代码只是来自 MSDN 的直接“复制”(可以这么说)。我用了MSDN's example作为编写它的指南并且仍然有一些工作要做(如删除它使用的阻塞性质)。目前，我只想知道如何将数据从主机发送到连接的客户端! :(

System.Net.Sockets.SocketException: A request to send or receive data was disall    owed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied
   at System.Net.Sockets.Socket.Send(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags)
   at System.Net.Sockets.Socket.Send(Byte[] buffer, Int32 size, SocketFlags socketFlags)
   at LabAssist.Server.Common.Objects.TcpServer.AcceptCallback(IAsyncResult ar) in F:\Source\ACCL\Lab Suite\Code\LabAssist.Server\Common\Objects\TcpServer.cs:li
ne 119

Answer 1

我建议使用 UDP 而不是带有手动 ACK 命令的 TCP，这样您就不会像老板那样获得持续连接的套接字。 UDP Information

我想说明的另一点是不要使用原始套接字作为您的第一个 TCP 连接，而是使用 TCPClient 类。 TCPClient