C#使用TcpClient实现telnet功能

using System;
using System.Collections.Generic;

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

namespace testTelnet

{
enum Verbs
{
WILL = 251,
WONT = 252,
DO = 253,
DONT = 254,
IAC = 255
}

enum Options
{
SGA = 3
}

class TelnetConnection

{
TcpClient tcpSocket;

int TimeOutMs = 1*1000;

public TelnetConnection(String Hostname,
int Port)
{
tcpSocket = new TcpClient(Hostname, Port);

}

public string Login(string Username,
string Password, int LoginTimeOutMs)

{
int oldTimeOutMs = TimeOutMs;

TimeOutMs = LoginTimeOutMs;
string s = Read();

if (!s.TrimEnd().EndsWith(":"))

throw
new Exception("Failed to connect : no login prompt");

WriteLine(Username);

s += Read();
if (!s.TrimEnd().EndsWith(":"))

throw new Exception("Failed to connect : no password prompt");

WriteLine(Password);

s += Read();
TimeOutMs = oldTimeOutMs;

return s;
}

public void DisConnect()

{
if (tcpSocket !=
null)
{
if (tcpSocket.Connected)

{
tcpSocket.Client.Disconnect(true);

}
}
}

public void WriteLine(string cmd)

{
Write(cmd + "\r\n");

}

public void Write(string cmd)

{
if (!tcpSocket.Connected)
return;

byte[] buf = System.Text.ASCIIEncoding.ASCII.GetBytes(cmd.Replace("\0xFF",
"\0xFF\0xFF"));
tcpSocket.GetStream().Write(buf, 0, buf.Length);
}

public string Read()

{
if (!tcpSocket.Connected)
return null;

StringBuilder sb = new StringBuilder();

do
{
ParseTelnet(sb);
System.Threading.Thread.Sleep(TimeOutMs);
} while (tcpSocket.Available > 0);

return ConvertToGB2312(sb.ToString());

}

public bool IsConnected

{
get { return tcpSocket.Connected; }

}

void ParseTelnet(StringBuilder sb)

{
while (tcpSocket.Available > 0)

{
int input = tcpSocket.GetStream().ReadByte();

switch (input)

{
case -1:

break;

case (int)Verbs.IAC:

// interpret as command

int inputverb = tcpSocket.GetStream().ReadByte();

if (inputverb == -1)
break;
switch (inputverb)

{
case (int)Verbs.IAC:

//literal IAC = 255 escaped, so append char 255 to string

sb.Append(inputverb);
break;

case (int)Verbs.DO:

case (int)Verbs.DONT:

case (int)Verbs.WILL:

case (int)Verbs.WONT:

// reply to all commands with "WONT", unless it is SGA (suppres go ahead)

int inputoption = tcpSocket.GetStream().ReadByte();

if (inputoption == -1)
break;
tcpSocket.GetStream().WriteByte((byte)Verbs.IAC);

if (inputoption == (int)Options.SGA)

tcpSocket.GetStream().WriteByte(inputverb == (int)Verbs.DO ? (byte)Verbs.WILL : (byte)Verbs.DO);

else

tcpSocket.GetStream().WriteByte(inputverb == (int)Verbs.DO ? (byte)Verbs.WONT : (byte)Verbs.DONT);

tcpSocket.GetStream().WriteByte((byte)inputoption);

break;

default:

break;

}
break;

default:

sb.Append((char)input);

break;

}
}
}

private string ConvertToGB2312(string str_origin)

{
char[] chars = str_origin.ToCharArray();

byte[] bytes = new
byte[chars.Length];
for (int i = 0; i < chars.Length; i++)

{
int c = (int)chars[i];

bytes[i] = (byte)c;

}
Encoding Encoding_GB2312 = Encoding.GetEncoding("GB2312");

string str_converted = Encoding_GB2312.GetString(bytes);

return str_converted;

}
}
}

// minimalistic telnet implementation
// conceived by Tom Janssens on 2007/06/06  for codeproject
//
// http://www.corebvba.be 
using System;
using System.Collections.Generic;
using System.Text;
using System.Net.Sockets;

namespace testTelnet
{
enum Verbs
{
WILL = 251,
WONT = 252,
DO = 253,
DONT = 254,
IAC = 255
}

enum Options
{
SGA = 3
}

class TelnetConnection
{
TcpClient tcpSocket;

int TimeOutMs = 1*1000;

public TelnetConnection(String Hostname, int Port)
{
tcpSocket = new TcpClient(Hostname, Port);

}

public string Login(string Username, string Password, int LoginTimeOutMs)
{
int oldTimeOutMs = TimeOutMs;
TimeOutMs = LoginTimeOutMs;
string s = Read();
if (!s.TrimEnd().EndsWith(":"))
throw new Exception("Failed to connect : no login prompt");
WriteLine(Username);

s += Read();
if (!s.TrimEnd().EndsWith(":"))
throw new Exception("Failed to connect : no password prompt");
WriteLine(Password);

s += Read();
TimeOutMs = oldTimeOutMs;

return s;
}

public void DisConnect()
{
if (tcpSocket != null)
{
if (tcpSocket.Connected)
{
tcpSocket.Client.Disconnect(true);
}
}
}

public void WriteLine(string cmd)
{
Write(cmd + "\r\n");
}

public void Write(string cmd)
{
if (!tcpSocket.Connected) return;

byte[] buf = System.Text.ASCIIEncoding.ASCII.GetBytes(cmd.Replace("\0xFF", "\0xFF\0xFF"));
tcpSocket.GetStream().Write(buf, 0, buf.Length);
}

public string Read()
{
if (!tcpSocket.Connected) return null;
StringBuilder sb = new StringBuilder();
do
{
ParseTelnet(sb);
System.Threading.Thread.Sleep(TimeOutMs);
} while (tcpSocket.Available > 0);

return ConvertToGB2312(sb.ToString());
}

public bool IsConnected
{
get { return tcpSocket.Connected; }
}

void ParseTelnet(StringBuilder sb)
{
while (tcpSocket.Available > 0)
{
int input = tcpSocket.GetStream().ReadByte();
switch (input)
{
case -1:
break;
case (int)Verbs.IAC:
// interpret as command
int inputverb = tcpSocket.GetStream().ReadByte();
if (inputverb == -1) break;
switch (inputverb)
{
case (int)Verbs.IAC:
//literal IAC = 255 escaped, so append char 255 to string
sb.Append(inputverb);
break;
case (int)Verbs.DO:
case (int)Verbs.DONT:
case (int)Verbs.WILL:
case (int)Verbs.WONT:
// reply to all commands with "WONT", unless it is SGA (suppres go ahead)
int inputoption = tcpSocket.GetStream().ReadByte();
if (inputoption == -1) break;
tcpSocket.GetStream().WriteByte((byte)Verbs.IAC);
if (inputoption == (int)Options.SGA)
tcpSocket.GetStream().WriteByte(inputverb == (int)Verbs.DO ? (byte)Verbs.WILL : (byte)Verbs.DO);
else
tcpSocket.GetStream().WriteByte(inputverb == (int)Verbs.DO ? (byte)Verbs.WONT : (byte)Verbs.DONT);
tcpSocket.GetStream().WriteByte((byte)inputoption);
break;
default:
break;
}
break;
default:
sb.Append((char)input);
break;
}
}
}

private string ConvertToGB2312(string str_origin)
{
char[] chars = str_origin.ToCharArray();
byte[] bytes = new byte[chars.Length];
for (int i = 0; i < chars.Length; i++)
{
int c = (int)chars[i];
bytes[i] = (byte)c;
}
Encoding Encoding_GB2312 = Encoding.GetEncoding("GB2312");
string str_converted = Encoding_GB2312.GetString(bytes);
return str_converted;
}
}
}

启动代码

[csharp]
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static void Main(string[] args)

{
//create a new telnet connection to hostname "gobelijn" on port "23"

TelnetConnection tc = new TelnetConnection("127.0.0.1", 23);

//login with user "root",password "rootpassword", using a timeout of 100ms,

//and show server output

string s = tc.Login("administrator",
"pw", 100);
Console.Write(s);

// server output should end with "{1}quot; or ">", otherwise the connection failed

string prompt = s.TrimEnd();

prompt = s.Substring(prompt.Length - 1, 1);

if (prompt != ":")

throw
new Exception("Connection failed");

prompt = "";

// while connected

while (tc.IsConnected && prompt.Trim() !=
"exit")
{
// display server output

Console.Write(tc.Read());

// send client input to server

prompt = Console.ReadLine();
tc.WriteLine(prompt);

// display server output

Console.Write(tc.Read());
}

Console.WriteLine("***DISCONNECTED");

Console.ReadLine();

}