source: binary-improvements/7dtd-server-fixes/src/AllocsTelnetConnection.cs@ 123

using System;
using System.Net;
using System.Net.Sockets;

public class AllocsTelnetConnection
{
        private bool authenticated = false;
        private bool authEnabled;
        private TcpClient client;
        private NetworkStream stream;
        private string lineBuffer = string.Empty;
        private EndPoint endpoint;

        public AllocsTelnetConnection (TcpClient client, bool authEnabled)
        {
                this.authEnabled = authEnabled;
                this.client = client;
                this.stream = client.GetStream ();
                this.endpoint = client.Client.RemoteEndPoint;
        }

        public EndPoint GetEndPoint ()
        {
                return endpoint;
        }

        private void WriteByte (byte v)
        {
                if (!IsClosed () && stream.CanWrite) {
                        stream.WriteByte (v);
                }
        }

        public void WriteLine (string s)
        {
                try {
                        if (!IsClosed () && stream.CanWrite) {
                                for (int i = 0; i < s.Length; i++) {
                                        WriteByte ((byte)s [i]);
                                }
                                WriteByte(13);
                                WriteByte (10);
                        }
                } catch (Exception e) {
                        Log.Out("Error writing to client: " + e);
                }
        }

        public void Close ()
        {
                if (client != null)
                        client.Close ();
                client = null;
        }

        public bool IsClosed ()
        {
                if (client != null && !client.Connected) {
                        Log.Out ("Telnet connection interrupted: " + endpoint);
                }
                return (client == null) || (!client.Connected);
        }

        public bool IsAuthenticated ()
        {
                return !authEnabled || authenticated;
        }

        public void SetAuthenticated ()
        {
                authenticated = true;
        }

        public bool Read ()
        {
                while (!IsClosed() && stream.CanRead && stream.DataAvailable) {
                        int b = stream.ReadByte ();
                        if (b == '\r' || b == '\n') {
                                if (lineBuffer.Length > 0)
                                        return true;
                        } else {
                                lineBuffer += (char)b;
                        }
                }
                return false;
        }

        public string GetLine ()
        {
                string res = lineBuffer;
                lineBuffer = string.Empty;
                return res;
        }
}