c# - TCP ZeroWindow 问题 C#

Question

我一直在用 C# 编写一个文件服务器/客户端应用程序，它似乎可以正常工作，但后来我意识到流没有被推进，客户端一直无法从服务器接收。所以我检查了 wireshark，发现我的客户端正在发出 TCPZeroWindow 标记的数据包。有什么想法吗？谢谢。

客户:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;
using System.IO;
namespace PortalClient
{
    class Program
    {
        static string s1;
        static byte[] data03;
        static int int02;
        static string str01;
        static int length;
        static IPEndPoint ipe01;
        static TcpClient tcp01;
        static FileStream s01;
        static string ip01;
        static string port01;
        static string path01;
        static byte[] data01;
        static byte[] data02;
        static byte[] data04;
        static void Main(string[] args)
        {

            while (true)
            {
            label1:
                {
                    try
                    {
                        string version = "V:1.1.4";
                        Console.Title = (" Portal Client " + version);
                        ConsoleColor ccolor1 = new ConsoleColor();
                        ccolor1 = Console.ForegroundColor;
                        Console.ForegroundColor = ConsoleColor.Green;
                        Console.WriteLine();
                        Console.WriteLine("         PORTAL CLIENT " + version);
                        Console.WriteLine();
                        Console.ForegroundColor = ccolor1;
                        data01 = new byte[20];
                        data03 = new byte[100];
                        data04 = new byte[100];
                        Console.Write(" Enter IPv4 address of server : ");
                        ip01 = Console.ReadLine();
                        Console.Write(" Enter port to connect on : ");
                        port01 = Console.ReadLine();
                        ipe01 = new IPEndPoint(IPAddress.Parse(ip01), Convert.ToInt32(port01));
                        tcp01 = new TcpClient();
                        tcp01.ReceiveTimeout = 2500;
                        tcp01.NoDelay = true;
                        Console.WriteLine(" Connecting...");
                        tcp01.Connect(ipe01);
                        Console.WriteLine(" Done.");
                        tcp01.Client.Receive(data04, SocketFlags.None);
                        System.Threading.Thread.Sleep(100);
                        Console.WriteLine(" Server message : " + Encoding.UTF8.GetString(data04));
                        tcp01.Client.Receive(data03, SocketFlags.None);
                        System.Threading.Thread.Sleep(100);
                        Console.WriteLine(" File on server : " + Encoding.UTF8.GetString(data03));
                        tcp01.Client.Receive(data01, SocketFlags.None);
                        System.Threading.Thread.Sleep(100);
                        str01 = Encoding.UTF8.GetString(data01);
                        Console.WriteLine();
                        Console.WriteLine(" file size : " + str01);
                        Console.WriteLine();
                        Console.Write(" Enter the number you see above : ");
                        length = Convert.ToInt32(Console.ReadLine());
                        Console.Write(" Save file as : ");
                        path01 = Console.ReadLine();
                        for (int i = 1; i <= 9000; i++)
                        {
                            if (length % i == 0) { int02 = i; }
                        }
                        if (length < 9000) { int02 = length; }
                        int int03 = length / int02;
                        s01 = File.OpenWrite(@path01);
                        Console.WriteLine(" Receiving file from " + tcp01.Client.RemoteEndPoint.ToString() + "...");
                        tcp01.Client.Send(new byte[1], SocketFlags.None);
                        System.Threading.Thread.Sleep(1000);
                        for (int i = 0; i <= int03; i++)
                        {
                            bool bool1 = false;
                            data02 = new byte[int02];
                            int n = tcp01.Client.Receive(data02, 0, int02, SocketFlags.None);
                            while (n < int02)
                            {
                                Console.WriteLine(" Entered Loop ");
                                int int04 = int02 - n;
                                tcp01.Client.Send(Encoding.UTF8.GetBytes("2"), 0, 1, SocketFlags.None);
                                int int05 = 0;
                                byte[] data05 = new byte[int04];
                                if (int04 >= 1 && int04 <= 9) { s1 = int04 + "xxx"; }
                                if (int04 >= 10 && int04 <= 99) { s1 = int04 + "xx"; }
                                if (int04 >= 100 && int04 <= 999) { s1 = int04 + "x"; }
                                if (int04 >= 1000 && int04 <= 9000) { s1 = int04.ToString(); }
                                tcp01.Client.Send(Encoding.UTF8.GetBytes(s1), 0, 4, SocketFlags.None);
                                int05 = tcp01.Client.Receive(data05, 0, int04, SocketFlags.None);
                                n = n + int05;
                                s01.Write(data05, 0, int05);
                                bool1 = true;
                            }
                            if (bool1 == false)
                            {
                                s01.Write(data02, 0, int02);
                                tcp01.Client.Send(new byte[1], 0, 1, SocketFlags.None);
                            }
                        }
                        System.Threading.Thread.Sleep(1000);
                        s01.Close();
                        Console.WriteLine(" Received all data.");
                        Console.WriteLine(" Press enter to disconnect...");
                        Console.ReadLine();
                        tcp01.Client.Send(new byte[1], SocketFlags.None);
                        System.Threading.Thread.Sleep(1000);
                        Console.WriteLine(" Disconnecting...");
                        tcp01.Close();
                        Console.WriteLine(" Done.");
                    }
                    catch (Exception e)
                    {
                        Console.WriteLine(" Error! : " + e.Message.ToString() + " - " + e.Data.ToString() + " - " + e.TargetSite.ToString()); if (!(tcp01 == null)) { tcp01.Close(); } if (!(s01 == null)) { s01.Close(); goto label1; }
                    }
                }

            }
        }
    }
}

服务器:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;
using System.IO;
namespace PortalServer
{
    class Program
    {
        static long length;
        static int int03;
        static int int02;
        static TcpListener tcp01;
        static TcpClient tcp02;
        static FileStream s01;
        static byte[] data01;
        static byte[] data03;
        static byte[] data04;
        static byte[] data05;
        static string str01;
        static string str02;
        static IPEndPoint ipe01;
        static string port01;
        static void Main(string[] args)
        {
            while (true)
            {
            label1:
                try
                {
                    string version = "V:1.1.4";
                    Console.Title = (" Portal Server " + version);
                    ConsoleColor ccolor1 = new ConsoleColor();
                    ccolor1 = Console.ForegroundColor;
                    Console.ForegroundColor = ConsoleColor.Green;
                    Console.WriteLine();
                    Console.WriteLine("         PORTAL SERVER " + version);
                    Console.WriteLine();
                    Console.ForegroundColor = ccolor1;
                    Console.Write(" Enter port for connecting clients : ");
                    port01 = Console.ReadLine();
                    Console.Write(" Enter path of file to send : ");
                    str01 = Console.ReadLine();
                    ipe01 = new IPEndPoint(IPAddress.Any, Convert.ToInt32(port01));
                    tcp01 = new TcpListener(ipe01);
                    Console.Write(" Enter server message : ");
                    str02 = Console.ReadLine();
                    s01 = File.OpenRead(@str01);
                    length = s01.Length;
                    for (int i = 1; i <= 9000; i++)
                    {
                        if (length % i == 0) { int02 = i; } 
                    }
                    if (length < 9000) { int02 = (int)length;}

                    int03 = (int)length / int02;
                    tcp01.Start();
                    Console.WriteLine(" Server started. Waiting for clients...");
                    tcp02 = tcp01.AcceptTcpClient();
                    tcp02.Client.NoDelay = true;
                    Console.WriteLine(" Client " + tcp02.Client.RemoteEndPoint.ToString() + " connected.");
                    data05 = Encoding.UTF8.GetBytes(str02);
                    tcp02.Client.Send(data05, SocketFlags.None);
                    System.Threading.Thread.Sleep(500);
                    data04 = Encoding.UTF8.GetBytes(str01);
                    tcp02.Client.Send(data04, SocketFlags.None);
                    System.Threading.Thread.Sleep(500);
                    data03 = Encoding.UTF8.GetBytes(length.ToString());
                    tcp02.Client.Send(data03, SocketFlags.None);
                    System.Threading.Thread.Sleep(500);
                    Console.WriteLine(" Waiting for response...");
                    tcp02.Client.Receive(new byte[1], SocketFlags.None);
                    Console.WriteLine(" Received response...");
                    Console.WriteLine(" Sending file to " + tcp02.Client.RemoteEndPoint.ToString() + "...");
                    System.Threading.Thread.Sleep(1);
                    for (int i = 0; i <= int03;i++ )
                    {
                        System.Threading.Thread.Sleep(30);
                        data01 = new byte[int02];
                        s01.Read(data01, 0, data01.Length);
                        int n = tcp02.Client.Send(data01, 0 ,data01.Length, SocketFlags.None);
                        if (n != int02) { throw new Exception("unable to write bytes, insufficient memory."); }
                        byte[] data07 = new byte[1];
                        while (true)
                        {
                            tcp02.Client.Receive(data07,0,1,SocketFlags.None);
                            if (Encoding.UTF8.GetString(data07) == "2") 
                            {
                                byte[] data06 = new byte[4];
                                int b = tcp02.Client.Receive(data06, 0, 4, SocketFlags.None);
                                if (b != 4) { throw new Exception("ex1"); }
                                string s1 = Encoding.UTF8.GetString(data06);
                                s1 = s1.Replace("x", "");
                                int int05 = Convert.ToInt32(s1);
                                int int06 = int02 - int05;
                                byte[] data08 = new byte[int05];
                                Buffer.BlockCopy(data01, int06, data08, 0, int05);
                                tcp02.Client.Send(data08, 0, data08.Length, SocketFlags.None);
                                System.Threading.Thread.Sleep(30);
                            }
                            break;
                        }
                    }
                    System.Threading.Thread.Sleep(1000);
                    s01.Close();
                    Console.WriteLine(" All data sent.");
                    Console.WriteLine(" Waiting for terminate message...");
                    tcp02.Client.Receive(new byte[1], SocketFlags.None);
                    Console.WriteLine(" Received terminate message.");
                    tcp02.Close();
                    Console.WriteLine(" Stopping client and server.");
                    tcp01.Stop();
                    Console.WriteLine(" Done. Restarting.");

                }

                catch (Exception e)
                {
                    Console.WriteLine(" Error! : " + e.Message.ToString() + " - " + e.Data.ToString() + " - " + e.TargetSite.ToString());
                    if (!(tcp02 == null)) { tcp02.Close(); }
                    if (!(tcp01 == null)) { tcp01.Stop(); goto label1; }
                }
            }
        }
    }
}

Answer 1

如果您没有在客户端正确清空网络缓冲区，并且 TCP 窗口大小因此减小为零，我已经看到会发生这种情况。

这可能发生在您使用

tcp01.Client.Receive(data04, SocketFlags.None);

可能没有充分清除缓冲区，请参阅 MSDN .您希望连续调用 Receive 直到没有更多数据可用。

如果您想要一个工作示例作为比较，请参阅 here .