计算机网络中GBN协议算法具体的C-Sharp代码

以下是GBN协议的C#代码实现：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;

namespace GBNProtocol
{
    class GBNClient
    {
        private const int TIMEOUT = 5000;
        private const int WINDOW_SIZE = 4;
        private const int BUFFER_SIZE = 256;
        private const int SERVER_PORT = 8888;
        private const string SERVER_IP = "127.0.0.1";

        private static int lastAck = 0;
        private static int lastSent = 0;
        private static int lastReceived = -1;

        static void Main(string[] args)
        {
            byte[][] message = new byte[WINDOW_SIZE][];
            bool[] acks = new bool[WINDOW_SIZE];
            IPEndPoint serverEndpoint = new IPEndPoint(IPAddress.Parse(SERVER_IP), SERVER_PORT);
            Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

            Console.Write("Enter message to send: ");
            string input = Console.ReadLine();
            byte[] data = Encoding.ASCII.GetBytes(input);

            while (lastAck < data.Length)
            {
                for (int i = lastSent; i <= Math.Min(lastSent + WINDOW_SIZE - 1, data.Length - 1); i++)
                {
                    message[i % WINDOW_SIZE] = new byte[BUFFER_SIZE];
                    data.CopyTo(message[i % WINDOW_SIZE], 0);
                    clientSocket.SendTo(message[i % WINDOW_SIZE], serverEndpoint);
                    lastSent++;
                }

                clientSocket.ReceiveTimeout = TIMEOUT;
                byte[] buffer = new byte[BUFFER_SIZE];

                try
                {
                    EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
                    int bytesReceived = clientSocket.ReceiveFrom(buffer, ref remoteEndPoint);

                    if (bytesReceived > 0)
                    {
                        string ackString = Encoding.ASCII.GetString(buffer, 0, bytesReceived);
                        int ack = Int32.Parse(ackString);

                        if (ack > lastAck && ack <= lastSent)
                        {
                            for (int i = lastAck + 1; i <= ack; i++)
                            {
                                acks[(i - 1) % WINDOW_SIZE] = true;
                            }

                            lastAck = ack;
                        }
                    }
                }
                catch (SocketException e)
                {
                    Console.WriteLine("Timeout. Resending packets...");
                    continue;
                }

                if (acks[lastReceived % WINDOW_SIZE])
                {
                    lastReceived++;
                }

                Array.Clear(message[lastReceived % WINDOW_SIZE], 0, BUFFER_SIZE);
                acks[lastReceived % WINDOW_SIZE] = false;
            }

            clientSocket.Close();
            Console.WriteLine("All packets sent and acknowledged.");
            Console.ReadKey();
        }
    }
}