c# - 侦听和接受连接的简单 Telnet 控制台

Question

我是 Telnet 和 C# 的新手，我正在尝试创建一个简单的控制台程序。我需要一个启动的 TCP 侦听器，侦听传入的网络连接并发送回响应。我并不真正关心传入的消息，但我需要接受它，以便客户端认为连接成功。此 TCP 侦听器将以“Hello”响应。我只需要确保它干净地启动并优雅地关闭 TCP 侦听器而不抛出任何异常。我需要使用“Telnet localhost 9090”连接到笔记本电脑上的 TCP 监听器的 9090 端口。

你能帮我吗？

Answer 1

使用TCPListener类。该示例回显从第二组代码中提供的客户端发送给它的字符串，因此它发送响应您好。您可以在运行下面的客户端代码时对此进行测试，该代码调用Socket.Receive以从服务器获取字符串：

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;

namespace tcplistener
{
    class Program
    {
        static void Main(string[] args)
        {
             TcpListener server = null;
        try
        {
            Int32 port = 9090;
            IPAddress localAddr = IPAddress.Parse("127.0.0.1");

            server = new TcpListener(localAddr, port);

            // Start listening for client requests.
            server.Start();

            // Buffer for reading data
            Byte[] bytes = new Byte[256];
            String data = null;

            // Enter the listening loop. 
            while (true)
            {
                Console.Write("Waiting for a connection... ");

                // Perform a blocking call to accept requests. 
                // You could also user server.AcceptSocket() here.
                TcpClient client = server.AcceptTcpClient();
                Console.WriteLine("Hello!");

                data = null;

                // Get a stream object for reading and writing
                NetworkStream stream = client.GetStream();

                int i;

                // Loop to receive all the data sent by the client. 
                while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
                {
                    // Translate data bytes to a ASCII string.
                    data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
                    Console.WriteLine("Received: {0}", data);

                    // Process the data sent by the client.
                    data = data.ToUpper();

                    byte[] msg = System.Text.Encoding.ASCII.GetBytes(data);

                    // Send back a response.
                    stream.Write(msg, 0, msg.Length);
                    Console.WriteLine("Sent: {0}", data);
                }

                // Shutdown and end connection
                client.Close();
            }
        }
        catch (SocketException e)
        {
            Console.WriteLine("SocketException: {0}", e);
        }
        finally
        {
            // Stop listening for new clients.
            server.Stop();
        }


        Console.WriteLine("\nHit enter to continue...");
        Console.Read();

        }
    }
}

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

namespace tcpconnect
{
    class Program
    {
        static void Main(string[] args)
        {
            Connect1("127.0.0.1", 9090);

            Console.Read();
        }

        // Synchronous connect using IPAddress to resolve the  
        // host name. 
        public static void Connect1(string host, int port)
        {
            IPAddress[] IPs = Dns.GetHostAddresses(host);

            Socket s = new Socket(AddressFamily.InterNetwork,
                SocketType.Stream,
                ProtocolType.Tcp);

            Console.WriteLine("Establishing Connection to {0}",
                host);
            s.Connect(IPs[0], port);

            byte[] howdyBytes = Encoding.ASCII.GetBytes("Howdy");
            s.Send(howdyBytes);
            byte[] buffer = new byte[50];
            s.Receive(buffer);
            Console.Write(Encoding.ASCII.GetString(buffer));
            Console.WriteLine("Connection established");
        }
    }
}

Answer 2

您可以使用我在 Internet 上找到的这个 Simple Telnet Server：https ://gist.github.com/UngarMax/6394321573dc0791dff9/

您可以将此代码作为您计划构建的程序的基础。