在简单的C＃tcp客户端/服务器程序中，我发送5个字节，服务器看到超过40万个字节。发生了什么事？

Question

我正在尝试研究一个简单的tcp客户端/服务器的基础知识，以便我可以实现一个通知系统，该系统几乎可以在任何地方工作，并允许像应用程序这样的“守护程序”进行通信。客户端之一可能是监视器，该监视器查看消息并显示所有重置的状态并进行协调，例如，通过暂停一个或多个，查看已处理了多少文件，数据库的状态等等。首先，我必须有一个非常简单的服务器，该服务器等待来自客户端的消息并将其广播到其他客户端。这是我目前在服务器上的尝试（基于http://csharp.net-informations.com/communications/csharp-chat-server.htm中的示例）。

using System;
using System.Threading;
using System.Net.Sockets;
using System.Text;
using System.Collections;

namespace erc.bre
{
    class NotificationServer
    {
        public static Hashtable clientsList = new Hashtable();

        static void Main(string[] args)
        {
            System.Net.IPAddress addr = System.Net.IPAddress.Parse("127.0.0.1");
            TcpListener serverSocket = new TcpListener(addr, 1025);
            TcpClient clientSocket = default(TcpClient);
            int counter = 0;

            serverSocket.Start();
            Console.WriteLine("Chat Server Started ....");
            counter = 0;
            while ((true))
            {
                counter += 1;
                clientSocket = serverSocket.AcceptTcpClient();

                byte[] bytesFrom = new byte[10025];
                clientSocket.ReceiveBufferSize = bytesFrom.Length; // added
                string dataFromClient = null;

                NetworkStream networkStream = clientSocket.GetStream();
             //   Console.WriteLine("Bytes received: {0}", (int)clientSocket.ReceiveBufferSize);
                networkStream.Read(bytesFrom, 0, (int)clientSocket.ReceiveBufferSize);
                dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
                dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));

                clientsList.Add(dataFromClient, clientSocket);

                broadcast(dataFromClient + " Joined ", dataFromClient, false);

                Console.WriteLine(dataFromClient + " Joined chat room ");
                handleClinet client = new handleClinet();
                client.startClient(clientSocket, dataFromClient, clientsList);
            }

            clientSocket.Close();
            serverSocket.Stop();
            Console.WriteLine("exit");
            Console.ReadLine();
        }

        public static void broadcast(string msg, string uName, bool flag)
        {
            foreach (DictionaryEntry Item in clientsList)
            {
                TcpClient broadcastSocket;
                broadcastSocket = (TcpClient)Item.Value;
                NetworkStream broadcastStream = broadcastSocket.GetStream();
                Byte[] broadcastBytes = null;

                if (flag == true)
                {
                    broadcastBytes = Encoding.ASCII.GetBytes(uName + " says : " + msg);
                }
                else
                {
                    broadcastBytes = Encoding.ASCII.GetBytes(msg);
                }

                broadcastStream.Write(broadcastBytes, 0, broadcastBytes.Length);
                broadcastStream.Flush();
            }
        }  //end broadcast function
    }//end Main class


    public class handleClinet
    {
        TcpClient clientSocket;
        string clNo;
        Hashtable clientsList;

        public void startClient(TcpClient inClientSocket, string clineNo, Hashtable cList)
        {
            this.clientSocket = inClientSocket;
            this.clientSocket.ReceiveBufferSize = 10025; // added
            this.clNo = clineNo;
            this.clientsList = cList;
            Thread ctThread = new Thread(doChat);
            ctThread.Start();
        }

        private void doChat()
        {
            int requestCount = 0;
            byte[] bytesFrom = new byte[10025];
            string dataFromClient = null;
            Byte[] sendBytes = null;
            string serverResponse = null;
            string rCount = null;
            requestCount = 0;

            while ((true))
            {
                try
                {
                    requestCount = requestCount + 1;
                    NetworkStream networkStream = clientSocket.GetStream();
                    networkStream.Read(bytesFrom, 0, (int)clientSocket.ReceiveBufferSize);
                    dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
                    dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));
                    Console.WriteLine("From client - " + clNo + " : " + dataFromClient);
                    rCount = Convert.ToString(requestCount);

                    NotificationServer.broadcast(dataFromClient, clNo, true);
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
            }//end while
        }//end doChat
    } //end class handleClinet
}//end namespace

您会注意到Console.WriteLine，我在其中打印出接收到的字节数。我添加了此内容，因为我在下一条声明大小超出范围的异常中得到了例外。它打印出一个408,000字节的数字。

这里是客户端程序，做了很多修改，因为在我的Mac版VisualStudio 2017中，我无法使用Windows窗体来创建任何项目，甚至无法按照示例创建项目。由于一旦确定了机制后就将代码放入Web应用程序中，因此我只是试图让客户端输入其ID，然后键入一行，让服务器选择并重新广播。其他客户端将从命令行执行相同的操作（每个新客户端一个）。它当前接受userId并将其发送。我发送“ John”，它似乎以5个字节发送“ John $”。

using System;
using System.Text;
using System.Net.Sockets;
using System.Threading;

namespace erc.bre
{
    public class NotificationClient
    {
        System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();
        NetworkStream serverStream = default(NetworkStream);
        string readData = null;
        string display = "";
        string userName = "";
        string message = "";
        bool needsInvocation = true;
        static NotificationClient nc = new NotificationClient();

        public NotificationClient()
        {
        }

        public static int Main(string[] args)
        {
            nc.msg();
            return 0;
        }

        private void sendUserJoined()
        {
            byte[] outStream = System.Text.Encoding.ASCII.GetBytes(message + "$");
            serverStream.Write(outStream, 0, outStream.Length);
            serverStream.Flush();
        }

        private void InputReceived()
        {
            readData = "Conected to Chat Server ...";
            msg();
            clientSocket.Connect("127.0.0.1", 1025);
            serverStream = clientSocket.GetStream();

            byte[] outStream = System.Text.Encoding.ASCII.GetBytes(userName + "$");
            Console.WriteLine("Sending {0} bytes as '{1}'", outStream.Length, System.Text.Encoding.Default.GetString(outStream);
            serverStream.Write(outStream, 0, outStream.Length);
            serverStream.Flush();

            Thread ctThread = new Thread(getMessage);
            ctThread.Start();
        }

        private void getMessage()
        {
            while (true)
            {
                serverStream = clientSocket.GetStream();
                int buffSize = 0;
                byte[] inStream = new byte[10025];
                buffSize = clientSocket.ReceiveBufferSize;
                serverStream.Read(inStream, 0, buffSize);
                string returndata = System.Text.Encoding.ASCII.GetString(inStream);
                readData = "" + returndata;
                msg();
            }
        }

        private void msg()
        {
            if (needsInvocation)
            {
                needsInvocation = false;
                Console.Out.WriteLine("Starting Client");
                Console.Out.WriteLine("Input your callerID: ");
                nc.userName = nc.ReadLine();
                nc.InputReceived();
                nc.sendUserJoined();
                nc.getMessage();
                return;
            }
            display = display + Environment.NewLine + " >> " + readData;
            Console.Out.WriteLine(display);
        }

        private string ReadLine()
        {
            string line = "";
            char ch;
            Console.WriteLine("Enter text when desired, 'enter' to end");
            do
            {
                int x = Console.Read();
                try
                {
                    ch = Convert.ToChar(x);
                    if (ch == 0x0a)
                    {
                        return line;
                    }
                }
                catch (OverflowException e)
                {
                    Console.WriteLine("{0} Value read = {1}.", e.Message, x);
                    ch = ' ';
                }
                line += ch;
            } while (ch != 0x0a);
            return line;
        }

    }
}

服务器控制台显示：

聊天服务器已启动.... 收到的字节数：408300

未处理的异常：System.ArgumentOutOfRangeException：指定的参数不在有效值范围内。 参数名称：大小    在System.Net.Sockets.NetworkStream.Read（Byte []缓冲区，Int32偏移量，Int32大小）    在/Users/woo/Projects/erc-caml/bre/NotificationServer/NotificationServer.cs:line 33中的ConsoleApplication1.NotificationServer.Main（String [] args）处 bash：第1行：45360中止陷阱：6“ / usr / local / share / dotnet / dotnet”“ /Users/woo/Projects/erc-caml/bre/NotificationServer/bin/Debug/netcoreapp2.1/NotificationServer.dll”

客户端控制台显示：

启动客户端 输入您的来电显示： 根据需要输入文本，“输入”以结束 约翰

  

    

已选择连接到聊天服务器...     发送5个字节作为“ John $”

  

未处理的异常：未处理的异常：System.ArgumentOutOfRangeException：指定的参数不在有效值范围内。 参数名称：大小    在System.Net.Sockets.NetworkStream.Read（Byte []缓冲区，Int32偏移量，Int32大小）    在/Users/woo/Projects/erc-caml/bre/NotificationMonitor/NotificationClient.cs:line 60中的erc.bre.NotificationClient.getMessage（）    在/Users/woo/Projects/erc-caml/bre/NotificationMonitor/NotificationClient.cs:line 77

中的erc.bre.NotificationClient.msg（）中

为什么服务器看到超过40万个字节？它在等待消息时在内部吞噬东西吗？不管我等了多久，这个数字看起来都一样。

Answer 1

clientSocket.ReceiveBufferSize

返回与接收字节数不匹配的接收缓冲区的大小。使用网络流（ serverStream ）的 Read 方法并检查其结果，该结果告诉您已读取了多少字节。

有关更多信息，请参见NetworkStream.Read(Byte[], Int32, Int32) Method和TcpClient.GetStream。