net.wimpi.telnetd.io
Class TelnetIO

java.lang.Object
  net.wimpi.telnetd.io.TelnetIO

public class TelnetIO

extends java.lang.Object

Class that represents the TelnetIO implementation. It contains an inner IACHandler class to handle the telnet protocol level communication.

Although supposed to work full-duplex, we only process the telnet protocol layer communication in case of reading requests from the higher levels. This is the only way to meet the one thread per connection requirement.

The output is done via byte-oriented streams, definately suitable for the telnet protocol. The format of the output is UTF-8 (Unicode), which is a standard and supported by any telnet client, including the ones included in Microsoft OS's.

Notes:

• The underlying output is buffered, to ensure that all bytes written are send, the flush() method has to be called.
• This low-level routines ensure nice multithreading behaviour on I/O. Neither large outputs, nor input sequences excuted by the connection thread can hog the system.

Version:

2.0 (13/03/2005)

Author:

Dieter Wimberger

Field Summary

protected static int	AO Abort Output
protected static int	AUTHENTICATION
protected static int	AYT Are You There
protected static int	BRK Break
protected static int	DM Data mark its the data part of a SYNCH which helps to clean up the buffers between Telnet Server <-> Telnet Client.
protected static int	DO Negotiation: Do option
protected static int	DONT Negotiation: Dont do option
protected static int	EC Erase Char
protected static int	ECHO Telnet Option: ECHO
protected static int	EL Erase Line
protected static int	ENCRYPT
protected static int	EXT_ASCII Unused
protected static int	GA Go Ahead Newer Telnets do not make use of this option that allows a specific communication mode.
protected static int	IAC Interpret As Command
protected static int	IP Interrupt Process
protected static int	IS TTYPE subnegotiation: IS
protected static int	LINEMODE Telnet Option: Linemode The infamous line mode option.
protected static int	LM_EDIT
protected static int	LM_FORWARDMASK
protected static int	LM_MODE
protected static int	LM_MODEACK
protected static int	LM_SLC
protected static int	LM_SLC_ABORT
protected static int	LM_SLC_ACK
protected static int	LM_SLC_AO
protected static int	LM_SLC_AYT
protected static int	LM_SLC_BRK
protected static int	LM_SLC_CANTCHANGE
protected static int	LM_SLC_DEFAULT
protected static int	LM_SLC_EOF
protected static int	LM_SLC_EOR
protected static int	LM_SLC_FLUSHIN
protected static int	LM_SLC_FLUSHOUT
protected static int	LM_SLC_IP
protected static int	LM_SLC_LEVELBITS
protected static int	LM_SLC_NOSUPPORT
protected static int	LM_SLC_SUSP
protected static int	LM_SLC_SYNCH
protected static int	LM_SLC_VALUE
protected static int	LM_TRAPSIG
protected static int	LOGOUT Telnet Option: Logout This allows nice goodbye to time-outed or unwanted clients.
protected static int	NAWS Telnet Option: Negotiate About Window Size Server request is IAC DO NAWS Client response contains subnegotiation with data (columns, rows).
protected static int	NE_ESC
protected static int	NE_IN_END
protected static int	NE_IN_ERROR
protected static int	NE_INFO
protected static int	NE_USERVAR
protected static int	NE_VALUE
protected static int	NE_VAR
protected static int	NE_VAR_DEFINED
protected static int	NE_VAR_DEFINED_EMPTY
protected static int	NE_VAR_NAME_MAXLENGTH
protected static int	NE_VAR_OK
protected static int	NE_VAR_UNDEFINED
protected static int	NE_VAR_VALUE_MAXLENGTH
protected static int	NEWENV Telnet Option: Environment
protected static int	NOP No operation
protected static int	SB Marks start of a subnegotiation.
protected static int	SE Marks end of subnegotiation.
protected static int	SEND TTYPE subnegotiation: SEND
protected static int	SEND_LOC
protected static int	SUPGA Telnet Option: SUPress Go Ahead This will be negotiated, all new telnet protocol implementations are recommended to do this.
protected static int	TTYPE Telnet Option: Terminal TYPE Server request contains subnegotiation SEND Client response contains subnegotiation with data IS,terminal type string
protected static int	WILL Negotiation: Will do option
protected static int	WONT Negotiation: Wont do option

Constructor Summary

TelnetIO()
Creates a TelnetIO object for the given connection.

Method Summary

void	closeInput() Method to close the underlying inputstream to free system resources.
void	closeOutput() Method to close the underlying output stream to free system resources.
void	flush() Method to flush all buffered output.
void	initIO()
int	read() Method to read a byte from the InputStream.
void	setConnection(Connection con)
void	setEcho(boolean b)
void	write(byte b) Method to output a byte.
void	write(byte[] sequence) Method to write an array of bytes.
void	write(char ch) Method to write a char.
void	write(int i) Method to output an int.
void	write(int[] sequence) Method to output an array of int' s.
void	write(java.lang.String str) Method to output a string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

IAC

protected static final int IAC

Interpret As Command

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Constant Field Values

GA

protected static final int GA

Go Ahead
Newer Telnets do not make use of this option that allows a specific communication mode.

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Constant Field Values

WILL

protected static final int WILL

Negotiation: Will do option

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Constant Field Values

WONT

protected static final int WONT

Negotiation: Wont do option

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Constant Field Values

DO

protected static final int DO

Negotiation: Do option

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Constant Field Values

DONT

protected static final int DONT

Negotiation: Dont do option

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Constant Field Values

SB

protected static final int SB

Marks start of a subnegotiation.

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SE

protected static final int SE

Marks end of subnegotiation.

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Constant Field Values

NOP

protected static final int NOP

No operation

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Constant Field Values

DM

protected static final int DM

Data mark its the data part of a SYNCH which helps to clean up the buffers between Telnet Server <-> Telnet Client.
It should work like this we send a TCP urgent package and <IAC> <DM> the receiver should get the urgent package (SYNCH) and just discard everything until he receives our <IAC> <DM>.
Remark:

1. can we send a TCP urgent package?
2. can we make use of the thing at all?

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Constant Field Values

BRK

protected static final int BRK

Break

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Constant Field Values

IP

protected static final int IP

Interrupt Process

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Constant Field Values

AO

protected static final int AO

Abort Output

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AYT

protected static final int AYT

Are You There

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Constant Field Values

EC

protected static final int EC

Erase Char

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EL

protected static final int EL

Erase Line

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Constant Field Values

ECHO

protected static final int ECHO

Telnet Option: ECHO

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Constant Field Values

SUPGA

protected static final int SUPGA

Telnet Option: SUPress Go Ahead
This will be negotiated, all new telnet protocol implementations are recommended to do this.

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Constant Field Values

NAWS

protected static final int NAWS

Telnet Option: Negotiate About Window Size

• Server request is IAC DO NAWS
• Client response contains subnegotiation with data (columns, rows).

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Constant Field Values

TTYPE

protected static final int TTYPE

Telnet Option: Terminal TYPE

• Server request contains subnegotiation SEND
• Client response contains subnegotiation with data IS,terminal type string

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Constant Field Values

IS

protected static final int IS

TTYPE subnegotiation: IS

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SEND

protected static final int SEND

TTYPE subnegotiation: SEND

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Constant Field Values

LOGOUT

protected static final int LOGOUT

Telnet Option: Logout
This allows nice goodbye to time-outed or unwanted clients.

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Constant Field Values

LINEMODE

protected static final int LINEMODE

Telnet Option: Linemode

The infamous line mode option.

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Constant Field Values

LM_MODE

protected static final int LM_MODE

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Constant Field Values

LM_EDIT

protected static final int LM_EDIT

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Constant Field Values

LM_TRAPSIG

protected static final int LM_TRAPSIG

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Constant Field Values

LM_MODEACK

protected static final int LM_MODEACK

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Constant Field Values

LM_FORWARDMASK

protected static final int LM_FORWARDMASK

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LM_SLC

protected static final int LM_SLC

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LM_SLC_NOSUPPORT

protected static final int LM_SLC_NOSUPPORT

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LM_SLC_DEFAULT

protected static final int LM_SLC_DEFAULT

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LM_SLC_VALUE

protected static final int LM_SLC_VALUE

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LM_SLC_CANTCHANGE

protected static final int LM_SLC_CANTCHANGE

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LM_SLC_LEVELBITS

protected static final int LM_SLC_LEVELBITS

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LM_SLC_ACK

protected static final int LM_SLC_ACK

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LM_SLC_FLUSHIN

protected static final int LM_SLC_FLUSHIN

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LM_SLC_FLUSHOUT

protected static final int LM_SLC_FLUSHOUT

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Constant Field Values

LM_SLC_SYNCH

protected static final int LM_SLC_SYNCH

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LM_SLC_BRK

protected static final int LM_SLC_BRK

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LM_SLC_IP

protected static final int LM_SLC_IP

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LM_SLC_AO

protected static final int LM_SLC_AO

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LM_SLC_AYT

protected static final int LM_SLC_AYT

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LM_SLC_EOR

protected static final int LM_SLC_EOR

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LM_SLC_ABORT

protected static final int LM_SLC_ABORT

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LM_SLC_EOF

protected static final int LM_SLC_EOF

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LM_SLC_SUSP

protected static final int LM_SLC_SUSP

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NEWENV

protected static final int NEWENV

Telnet Option: Environment

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Constant Field Values

NE_INFO

protected static final int NE_INFO

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NE_VAR

protected static final int NE_VAR

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NE_VALUE

protected static final int NE_VALUE

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NE_ESC

protected static final int NE_ESC

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NE_USERVAR

protected static final int NE_USERVAR

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NE_VAR_OK

protected static final int NE_VAR_OK

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NE_VAR_DEFINED

protected static final int NE_VAR_DEFINED

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NE_VAR_DEFINED_EMPTY

protected static final int NE_VAR_DEFINED_EMPTY

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NE_VAR_UNDEFINED

protected static final int NE_VAR_UNDEFINED

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NE_IN_ERROR

protected static final int NE_IN_ERROR

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NE_IN_END

protected static final int NE_IN_END

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NE_VAR_NAME_MAXLENGTH

protected static final int NE_VAR_NAME_MAXLENGTH

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NE_VAR_VALUE_MAXLENGTH

protected static final int NE_VAR_VALUE_MAXLENGTH

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Constant Field Values

EXT_ASCII

protected static final int EXT_ASCII

Unused

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SEND_LOC

protected static final int SEND_LOC

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AUTHENTICATION

protected static final int AUTHENTICATION

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ENCRYPT

protected static final int ENCRYPT

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Constructor Detail

TelnetIO

public TelnetIO()

Creates a TelnetIO object for the given connection.
Input- and OutputStreams are properly set and the primary telnet protocol initialization is carried out by the inner IACHandler class.

Method Detail

initIO

public void initIO()
            throws java.io.IOException

Throws:

java.io.IOException

setConnection

public void setConnection(Connection con)

write

public void write(byte b)
           throws java.io.IOException

Method to output a byte. Ensures that CR(\r) is never send alone,but CRLF(\r\n), which is a rule of the telnet protocol.

Parameters:

b - Byte to be written.

Throws:

java.io.IOException

write

public void write(int i)
           throws java.io.IOException

Method to output an int.

Parameters:

i - Integer to be written.

Throws:

java.io.IOException

write

public void write(byte[] sequence)
           throws java.io.IOException

Method to write an array of bytes.

Parameters:

sequence - byte[] to be written.

Throws:

java.io.IOException

write

public void write(int[] sequence)
           throws java.io.IOException

Method to output an array of int' s.

Parameters:

sequence - int [] to write

Throws:

java.io.IOException

write

public void write(char ch)
           throws java.io.IOException

Method to write a char.

Parameters:

ch - char to be written.

Throws:

java.io.IOException

write

public void write(java.lang.String str)
           throws java.io.IOException

Method to output a string.

Parameters:

str - String to be written.

Throws:

java.io.IOException

flush

public void flush()
           throws java.io.IOException

Method to flush all buffered output.

Throws:

java.io.IOException

closeOutput

public void closeOutput()

Method to close the underlying output stream to free system resources.
Most likely only to be called by the ConnectionManager upon clean up of connections that ended or died.

read

public int read()
         throws java.io.IOException

Method to read a byte from the InputStream. Invokes the IACHandler upon IAC (Byte=255).

Returns:

int read from stream.

Throws:

java.io.IOException

closeInput

public void closeInput()

Method to close the underlying inputstream to free system resources.
Most likely only to be called by the ConnectionManager upon clean up of connections that ended or died.

setEcho

public void setEcho(boolean b)