dotNetStudyWithGPT/MySolution/ConsoleApp/TelnetSamples/AsyncSocketTelnetClient.cs

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

namespace ConsoleApp.TelnetSamples
{
	internal class AsyncSocketTelnetClient : IAsyncTelnetClient
	{
		private CancellationTokenSource _cts;

		public event EventHandler<string> MessageCallback;
		public event EventHandler<Exception> ErrorCallback;

        private Socket _socket;

		public async void Connect(string ip, int port = 23)
		{
			try
			{
				//Close();

				_socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
				_socket.ReceiveTimeout = 1000;

				IPAddress ipAddress = Dns.GetHostAddresses(ip)[0];
				IPEndPoint iPEndPoint = new IPEndPoint(ipAddress, port);
				await _socket.ConnectAsync(iPEndPoint);

				_cts = new CancellationTokenSource();
				Task.Run(ReadAsync, _cts.Token);
			}
			catch (Exception ex)
			{
                if (this.ErrorCallback != null)
                    this.ErrorCallback(this, ex);
            }
		}

		private async void ReadAsync()
		{
			try
			{
				StringBuilder sb = new StringBuilder();
				byte[] readBuffer = new byte[1024];
				while (true)
				{
					//Thread.Sleep(100);
					if (_cts.IsCancellationRequested)
						break;

					int bytesRead = await _socket.ReceiveAsync(readBuffer);
					if (bytesRead < 1)
					{
						if (sb.Length > 0 && this.MessageCallback != null)
							this.MessageCallback(this, sb.ToString());

                        break;
                    }

                    string data = Encoding.ASCII.GetString(readBuffer, 0, bytesRead);
					sb.Append(data);

					if (!data.EndsWith("\r\n>"))
						continue;

					// 에코 삭제
					string read = sb.ToString();
					int rnIdx = read.IndexOf("\r\n");
					read = read.Substring(rnIdx + 1);

					if (this.MessageCallback != null)
						this.MessageCallback(this, read);

					sb.Clear();
				}
			}
            catch (Exception ex)
            {
                if (this.ErrorCallback != null)
                    this.ErrorCallback(this, ex);
            }
        }

		public async void SendCommand(string command)
		{
			try
			{
				command = command.Replace(" ", "");
				if (string.IsNullOrEmpty(command))
					return;

				command += "\r\n";
				byte[] sendBytes = Encoding.ASCII.GetBytes(command);
				await _socket.SendAsync(sendBytes);
			}
            catch (Exception ex)
            {
                if (this.ErrorCallback != null)
                    this.ErrorCallback(this, ex);
            }
        }

		public void Close()
		{
			try
			{
				if (_socket == null)
					return;

				_cts.Cancel();

				_socket.Shutdown(SocketShutdown.Both);
				_socket.Close();
				_socket.Dispose();
			}
            catch (Exception ex)
            {
                if (this.ErrorCallback != null)
                    this.ErrorCallback(this, ex);
            }
        }
	}
}