通过套接字在 C# 中传输一半文件？

Question

我正在通过中级贪婪路由开发文件传输应用程序，其中文件发送到贪婪，贪婪再次将文件发送到路由器但他的问题是有时客户端会收到完整的文件，有时会收到文件的一部分

这是我的代码服务器端

IPAddress[] ipAddress = Dns.GetHostAddresses("127.0.0.1");
            IPEndPoint ipEnd = new IPEndPoint(ipAddress[0], 5655);
            Socket clientSock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);


            string filePath = "";


            fileDes = fileDes.Replace("\", "/");
            while (fileDes.IndexOf("/") > -1)
            {
                filePath += fileDes.Substring(0, fileDes.IndexOf("/") + 1);
                fileDes = fileDes.Substring(fileDes.IndexOf("/") + 1);
            }


            byte[] fileNameByte = Encoding.ASCII.GetBytes(fileDes);

            lblError.Text = "";
            lblError.Text = "Buffering ...";
            byte[] fileData = File.ReadAllBytes(filePath + fileDes);
            byte[] clientData = new byte[4 + fileNameByte.Length + fileData.Length];
            byte[] fileNameLen = BitConverter.GetBytes(fileNameByte.Length);

            fileNameLen.CopyTo(clientData, 0);
            fileNameByte.CopyTo(clientData, 4);
            fileData.CopyTo(clientData, 4 + fileNameByte.Length);

            lblError.Text = "";
            lblError.Text = "Connection to server ...";
            clientSock.Connect(ipEnd);

            lblError.Text = "";
            lblError.Text = "File sending...";
         //   System.Threading.Thread.Sleep(1000);
            clientSock.Send(clientData);
            label3.Text = clientData.Length.ToString();

            lblError.Text = "";
            lblError.Text = "Disconnecting...";
            clientSock.Close();

            lblError.Text = "";
            lblError.Text = "File transferred.";

在客户端

class DestCode
{
    IPEndPoint ipEnd;
    Socket sock;
    public DestCode()
    {
       ipEnd = new IPEndPoint(IPAddress.Any, 5656);
       sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
       sock.Bind(ipEnd);
    }
    public static string receivedPath;
    public static string curMsg = "Stopped";
    public static int res;
    public  void StartServer()
    {
        try
        {
            curMsg = "Starting...";
            sock.Listen(100);

            curMsg = "Running and waiting to receive file.";
            Socket clientSock = sock.Accept();

            byte[] clientData = new byte[1024 * 5000];

            int receivedBytesLen = clientSock.Receive(clientData);

            curMsg = "Receiving data...";

            int fileNameLen = BitConverter.ToInt32(clientData, 0);
            string fileName = Encoding.ASCII.GetString(clientData, 4, fileNameLen);

            BinaryWriter bWrite = new BinaryWriter(File.Open(receivedPath +"/"+ fileName, FileMode.Append)); ;
            bWrite.Write(clientData,4 + fileNameLen, receivedBytesLen - 4 - fileNameLen);
            res = receivedBytesLen;
            if (receivedPath == "")
            {
                MessageBox.Show("No Path was selected to Save the File");
            }
            curMsg = "Saving file...";

            bWrite.Close();
            clientSock.Close();
            curMsg = "File Received ...";

            StartServer();

        }
        catch (Exception ex)
        {
            curMsg = "File Receving error.";
        }
    }
}

贪心

class ReceiverCode
{
    IPEndPoint ipEnd;
    Socket sock;
    public ReceiverCode()
    {
        ipEnd = new IPEndPoint(IPAddress.Any, 5655);
        sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
        sock.Bind(ipEnd);
    }
    public static string receivedPath;
    public static string curMsg = "Stopped";
    public static string Rout = "";
    public static int rlength = 0;
    public static string MsgStatus = "";
    public static byte[] send;
    public void StartServer()
    {
        try
        {
            curMsg = "Starting...";
            sock.Listen(100);

            curMsg = "Running and waiting to receive file.";
            Socket clientSock = sock.Accept();

            byte[] clientData = new byte[1024 * 5000];

            int receivedBytesLen = clientSock.Receive(clientData);
           System.Threading.Thread.Sleep(5000);
            rlength = receivedBytesLen;
            curMsg = "Receiving data...";

            int receive = clientSock.Receive(clientData);


            send = new byte[receivedBytesLen];
            Array.Copy(clientData, send, receivedBytesLen);
            Rout = "Start";
            clientSock.Close();
            curMsg = "Reeived & Saved file; Server Stopped.";
            StartServer();

        }
        catch (Exception ex)
        {
            curMsg = "File Receving error.";
        }
    }


}

请有人帮助我

Answer 1

问题是 Socket.Receive 不能保证您会收到您要求的所有字节。所以你写：

int receivedBytesLen = clientSock.Receive(clientData);

documentation 说：

If you are using a connection-oriented Socket, the Receive method will read as much data as is available, up to the size of the buffer.

对 Receive 的调用正在获取当前可用的所有字节。可能是发件人尚未发送所有字节，或者您的网络堆栈尚未收到并使它们可用。

为了可靠地发送和接收数据，接收方必须知道以下两件事之一：它期望有多少字节，或者有一些标记值表明，"that's all, folks." 你不能指望一次 Receive 调用即可获取所有内容。

传输文件时，发件人通常将文件的大小作为要发送的数据的前四个字节。然后您的代码读取前四个字节（确保您获得所有四个字节）以确定大小，然后旋转一个循环，从套接字读取数据，直到收到所有预期的字节。

类似于：

const int MaximumSize = 1000000;
// read the first four bytes
var sizeBytes = ReadBytesFromSocket(socket, 4);
int size = BitConverter.ToInt32(sizeBytes);

var dataBuffer = ReadBytesFromSocket(socket, size);
// you now have your data

byte[] ReadBytesFromSocket(Socket socket, int size)
{
    var buff = new byte[size];
    int totalBytesRead = 0;

    while (totalBytesRead < size)
    {
        int bytesRead = socket.Receive(buff, totalBytesRead, size-totalBytesRead, SocketFlags.None);
        if (bytesRead == 0)
        {
            // nothing received. The socket has been closed.
            // maybe an error.
            break;
        }
        totalBytesRead += bytesRead
    }
    return buff;
}

有关详细信息，请参阅我在 reading streams 上的博客 post（以及链接的第 1 部分和第 2 部分）。博客 post 讨论流，但概念与套接字相同。

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