Question

目前我正在编写一个C＃程序，旨在满足计算机网络类项目，该程序可以用任何语言编写（我选择了C＃），并且必须执行某种网络多媒体处理。它可以是基于对等或基于客户端的服务器。

我选择将我的应用程序Peer to Peer。客户端使用UDP将其连接/断开连接广播到本地网络上的其他客户端，然后使用TCP在彼此之间发送和接收.WAV文件。

在连接请求时，客户端将接受TCP连接并开始从发送客户端读取数据。

数据全部读完后，客户端可以播放.WAV文件。

我目前一直在尝试修复程序中的一个错误，该错误要求.WAV文件被发送两次而不是一次，以便接收者获取文件并播放它。

这导致我遇到了之前遇到的问题：Wave标头已损坏。

之前，我遇到过这个问题，因为在播放.WAV文件时，我没有将流位置设置为0.这是第一次修复它。

然而，原因现在更加有趣，因为我正在尝试修复另一个错误。

这次的原因是.WAV文件流中的数据被拆分。开始时，数据的第一个字节是正确的（通过使用hexeditor查看.WAV文件中我尝试发送/接收的字节进行验证）然后流填充1023字节的0＆＃39; S。之后，.WAV文件的其余数据可用，没有拆分。

（另一个发送/ recv试验显示第一个字节再次正确，但接下来的1023个字节不同步并且放错位置。接下来的1023个字节不是0x00，而是来自错误放置的另一个文件。）

我不知道造成这种情况的原因是什么导致Wireshark试图找出问题所在。我在接收端进行了wireshark捕获，发现发送的第一个数据包只有1个字节的数据：0x52。

下一个数据包有1460个字节。在NetworkStream中的那1460个字节之后没有拆分0x00。

以下是我的程序代码。也可以在https://github.com/cparks1/ECE369ProjB-MultimediaGUI

的Github上找到它

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

using System.Net.Sockets; // For network programming
using System.Net; // For network programming
using System.Media; // For playing .WAV files
using System.IO; // For playing .WAV files (SoundPlayer in System.Media accepts either a filepath or an IO stream.)

namespace ProjectBMultimediaGUI
{

public partial class Form1 : Form
{
    private delegate void ObjectDelegate(string msg, IPEndPoint sender);
    private delegate void LabelChanger(string msg);

    const int PUBLISH_PORT_NUMBER = 8030; // Port number used for publish (UDP communications)
    const int TCP_PORT_NUMBER = 8031; // Port number used for the rest of communications (TCP communications)
    IPAddress me = GetLocalIP(); // me is the IPAddress that your machine currently owns on the local network

    const string CLIENT_ANNOUNCE = "[ECE 369] Multimedia client publish"; // UDP datagram to be sent when the client is announcing itself
    const string CLIENT_DISCONNECT = "[ECE 369] Multimedia client disconnect"; // UDP datagram to be sent when the client is announcing that it is disconnecting

    UdpClient pub = new UdpClient(PUBLISH_PORT_NUMBER, AddressFamily.InterNetwork); // Creates a new UDP client capable of communicating on a network on port defined by const, via IPv4 addressing
    IPEndPoint UDP_BROADCAST = new IPEndPoint(IPAddress.Broadcast, PUBLISH_PORT_NUMBER); // Broadcast address and port

    TcpListener tlisten = new TcpListener(IPAddress.Any,TCP_PORT_NUMBER); // Sets up a listener that looks for TCP connections
    TcpClient tcprecvr;

    Stream wavstream = new MemoryStream(); // Initializes a memory stream that will hold .wav file data when being written to. Will be reinitialized in packet receiving functions

    Timer tmr = new Timer(); // Timer used to announce client on the local network every 250 ms

    SoundPlayer splayer;

    bool isClosing = false; // Used to determine if program is closing

    byte[] readbuf = new byte[1024];
    long wavpos = 0;

    public Form1()
    {
        InitializeComponent();
        #region Timer Setup
        tmr.Interval = 250;
        tmr.Start();
        tmr.Tick += new EventHandler(tmr_Tick);
        #endregion
    }

    private void tmr_Tick(object sender, EventArgs e)
    {
        if (!isClosing)
            Announce_Client_Connect(); // Announce the client is connected every 250 ms
    }

    private void playpauseBUT_MouseClick(object sender, MouseEventArgs e)
    {
        Button sbut = (sender as Button);
        splayer = new SoundPlayer(wavstream);
        if (sbut.ImageIndex == 0) // If the PLAY button was clicked
        { // Initiate play functions
            if (wavstream.CanRead && wavstream.Length > 0)
            {
                splayer.Stream.Position = 0;
                splayer.Play();
            }
            sbut.ImageIndex = 1; // Change the button to show PAUSE
        }
        else // If the PAUSE button was clicked
        {
            splayer.Stop();
            sbut.ImageIndex = 0; // Change the button to show PLAY
        }
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        butIML.ImageSize = new Size(playpauseBUT.Size.Width-1,playpauseBUT.Size.Height-1); // This ensures the play and pause buttons are always the same size as the button they are encased in
        stopBUT.Size = playpauseBUT.Size; // Ensures the stop button is the same size as the play/pause button.
        stopBUT.Location = new Point(stopBUT.Location.X, playpauseBUT.Location.Y);

        pub.AllowNatTraversal(false); // Disables the ability for the program to communicate with the outside world, for security purposes
        try { pub.BeginReceive(new AsyncCallback(RecvPub), null); }
        catch(Exception err) { MessageBox.Show("An error occurred!\n"+err.ToString()); Application.Exit(); }

        tlisten.AllowNatTraversal(false);
        BeginListening(); // Begins listening for attempts to connect to the client via TCP
        Announce_Client_Connect();
    }

    private void BeginListening()
    {
        tlisten.Start();
        tlisten.BeginAcceptTcpClient(new AsyncCallback(RecvTcp), null);
    }

    private void stopBUT_MouseClick(object sender, MouseEventArgs e)
    {
        splayer.Stop();
        playpauseBUT.ImageIndex = 0; // Change the play/pause button to show PLAY
    }

    private void mainMS_Paint(object sender, PaintEventArgs e)
    {
        e.Graphics.DrawLine(new Pen(Color.Black), mainMS.Left, mainMS.Bottom-1, mainMS.Right, mainMS.Bottom-1); // Draws a border on the bottom of the main menu strip.
        e.Graphics.DrawLine(new Pen(Color.Black), mainMS.Left, mainMS.Top, mainMS.Right, mainMS.Top); // Draws a border on the top of the menu strip.
    }

    private void RecvPub(IAsyncResult res) // Function used to handle received UDP messages
    {
        IPEndPoint recv = new IPEndPoint(IPAddress.Any, PUBLISH_PORT_NUMBER);
        byte[] message = null;
        string dmessage;
        if (!isClosing)
            message = pub.EndReceive(res, ref recv);

        if(message != null) // If a message was received
        {
            ObjectDelegate del = new ObjectDelegate(HandleUDPDatagram);
            dmessage = Encoding.ASCII.GetString(message);
            del.Invoke(dmessage, recv);
            HandleUDPDatagram(dmessage, recv);
        }

        if (!isClosing)
            pub.BeginReceive(new AsyncCallback(RecvPub), null);
    }

    private void RecvTcp(IAsyncResult res)
    {
        LabelChanger lblchgr = new LabelChanger(dataavailable); // Used for cross thread operations on dataavailLBL

        wavstream = new MemoryStream(); // Clear the wav stream, we don't want two wav files in one stream, it would cause errors.

        lblchgr.Invoke("Data unavailable."); // No data available yet.

        //tcprecvr = tlisten.AcceptTcpClient(); // Accept the incoming TCP connection.
        tcprecvr = tlisten.EndAcceptTcpClient(res); // Create a new TCP connection with the requester
        NetworkStream stream = tcprecvr.GetStream(); // Get the TCP network stream
        if (stream.CanRead)
        {
            while (!stream.DataAvailable) ;
            stream.BeginRead(readbuf, 0, readbuf.Length, new AsyncCallback(RecvTCPData), null);
        }
        else
        {
            tcprecvr.Close();
            MessageBox.Show("An error has occurred. Unable to read incoming TCP stream.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
        }
    }

    private void RecvTCPData(IAsyncResult res)
    {
        LabelChanger lblchgr = new LabelChanger(dataavailable); // Used for cross thread operations on dataavailLBL

        wavpos = 0; // Reset the WAV stream position

        NetworkStream stream = tcprecvr.GetStream(); // Get the TCP data stream
        int nbytes = stream.EndRead(res); // Get the number of bytes read
        if (nbytes == 0) // Finished reading
        {
            tcprecvr.Close(); // Close the TCP connection
            lblchgr.Invoke("Data available!"); // Inform the user there is a .WAV file to be played
            BeginListening(); // Begin listening to connection requests again
            //return;
        }
        else // Not finished reading, data in buffer
        {
            wavstream.Write(readbuf, 0, readbuf.Length); // Write WAV data to wav stream
            stream.BeginRead(readbuf, 0, readbuf.Length, new AsyncCallback(RecvTCPData), null); // begin read again
        }
    }

    private void dataavailable(string msg)
    {
        if(InvokeRequired)
        {
            LabelChanger method = new LabelChanger(dataavailable);
            Invoke(method, msg);
            return;
        }
        dataavailLBL.Text = "Data available!";
    }

    private void HandleUDPDatagram(string msg, IPEndPoint sender) // Used for handling UDP messages
    {
        if (!sender.Address.Equals(me)) // Verifies the UDP datagram received isn't from your own machine.
        { //This is done because some UDP datagrams are sent to the broadcast address, which means we receive what we've sent. We obviously don't want packets from ourselves so we block them.
            if (InvokeRequired && !isClosing) // Used for handling thread magic. Please don't ask me to explain this.
            {
                ObjectDelegate method = new ObjectDelegate(HandleUDPDatagram);
                Invoke(method, msg, sender);
                return;
            }

            switch (msg)
            {
                case CLIENT_ANNOUNCE: // If we've received a client connection message
                    if (!hostsLB.Items.Contains(sender.Address)) // If the client is not already in the list box
                        hostsLB.Items.Add(sender.Address); // Add the client to the listbox of clients
                    break;
                case CLIENT_DISCONNECT: // If we've received a client disconnection message
                    if (hostsLB.Items.Contains(sender.Address)) // If the client is in the listbox
                        hostsLB.Items.Remove(sender.Address); // Remove the client from the listbox of clients
                    break;
            }
        }
    }

    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        isClosing = true;
        Announce_Client_Disconnect(); // Declare your disconnection to the other clients on the network
    }

    private void Announce_Client_Disconnect()
    {
        byte[] dgram = Encoding.ASCII.GetBytes(CLIENT_DISCONNECT); // Encode the client disconnection message into an array of bytes
        pub.Send(dgram, dgram.Length, UDP_BROADCAST); // Send the disconnection message off to all clients on the network via the broadcast address
    }

    private void Announce_Client_Connect()
    {
        byte[] dgram = Encoding.ASCII.GetBytes(CLIENT_ANNOUNCE); // Encode the client connection message into an array of bytes
        pub.Send(dgram, dgram.Length, UDP_BROADCAST); // Send the connection message off to all clients on the network via the broadcast address
    }

    private void OpenBrowse()
    { // This function allows the user to browse for a file and then sets the file path textbox with the path of the file.
        OpenFileDialog fopen = new OpenFileDialog();
        fopen.CheckFileExists = true; fopen.CheckPathExists = true; fopen.Filter = "WAV Files|*.wav";
        fopen.ShowDialog();
        filepathTB.Text = fopen.FileName;
    }

    private void sendwavBUT_MouseClick(object sender, MouseEventArgs e)
    {
        if (hostsLB.Items.Count > 0 && hostsLB.SelectedItem != null)
        {
            TcpClient tcpsender = new TcpClient((hostsLB.SelectedItem as IPAddress).ToString(),TCP_PORT_NUMBER); // Connect to the client

            sendwavBUT.Enabled = false; filesendPB.UseWaitCursor = true;
            try
            {
                //byte[] buf = new byte[1024]; // !! TRIAL !!
                FileStream fs = new FileStream(filepathTB.Text, FileMode.Open);
                int dat = 0;
                while(fs.CanRead && fs.Position!=fs.Length)
                {
                    dat = fs.ReadByte();
                    if (dat != -1)
                    {
                        tcpsender.GetStream().WriteByte((byte)dat);
                        filesendPB.Value = (int)((fs.Position / fs.Length) * 100);
                    }
                }
                fs.Close(); // Release any resources used by the file stream.
            }
            catch(Exception err) { MessageBox.Show(err.ToString(),"Error",MessageBoxButtons.OK,MessageBoxIcon.Error); }

            MessageBox.Show("File send complete.");
            tcpsender.Close(); // Release any resources used by the TCP stream and close the TCP connection.
            sendwavBUT.Enabled = true; filesendPB.UseWaitCursor = false; // Re-enable the send button.
        }
        else if (hostsLB.Items.Count <= 0)
            MessageBox.Show("There are no clients to send this file to!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        else
            MessageBox.Show("You must select a client!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
    }

    static IPAddress GetLocalIP() // Has the machine report its local network IP address
    { // This code snippet has been taken from StackOverflow and adapted to return an IPAddress rather than a string
        IPHostEntry host;
        host = Dns.GetHostEntry(Dns.GetHostName());
        foreach (IPAddress ip in host.AddressList)
            if (ip.AddressFamily.ToString() == "InterNetwork")
                return ip;

        return null;
    }

    private void closeToolStripMenuItem_Click(object sender, EventArgs e)
    { Application.Exit(); }
    private void openToolStripMenuItem_Click(object sender, EventArgs e)
    { OpenBrowse(); }
    private void browseBUT_MouseClick(object sender, MouseEventArgs e)
    { OpenBrowse(); }
}
}

还提供了GUI的图片：

感谢您提供的任何意见，这个问题让我疯狂！：）

Answer 1

只看流读/写，看起来你在这行上有一个错误：

wavstream.Write(readbuf, 0, readbuf.Length); // Write WAV data to wav stream

应该是：

wavstream.Write(readbuf, 0, nbytes); // Write WAV data to wav stream

C＃程序为NetworkStream填充0＆＃39;整个1023字节，第一个字节正确

1 个答案: