source: binary-improvements/7dtd-server-fixes/src/NetConnections/Servers/Telnet/TelnetConnection.cs@ 180

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

namespace AllocsFixes.NetConnections.Servers.Telnet
{
        public class TelnetConnection : IConnection
        {
                private bool authenticated = false;
                private bool authEnabled;
                private TcpClient client;
                private NetworkStream stream;
                private int lineBufferLength = 0;
                private byte[] lineBuffer = new byte[200];
                private EndPoint endpoint;

                public TelnetConnection (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) {
                                        byte[] utfData = Encoding.UTF8.GetBytes (s);
                                        stream.Write (utfData, 0, utfData.Length);
                                        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 (lineBufferLength > 0) {
                                                return true;
                                        }
                                } else if (b >= 0) {
                                        lineBuffer [lineBufferLength] = (byte)b;
                                        lineBufferLength++;
                                }
                        }
                        return false;
                }

                public string GetLine ()
                {
                        string res = Encoding.UTF8.GetString (lineBuffer, 0, lineBufferLength);
                        lineBufferLength = 0;
                        return res;
                }

        }
}