Package org.jline.builtins.telnet

Class TelnetIO

java.lang.Object

org.jline.builtins.telnet.TelnetIO

public class TelnetIO
extends 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 (16/07/2006)

Author:

Dieter Wimberger

Field Summary

Fields

Modifier and Type	Field	Description
protected static final int	AO	Abort Output
protected static final int	AUTHENTICATION
protected static final int	AYT	Are You There
protected static final int	BRK	Break
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.
protected static final int	DO	Negotiation: Do option
protected static final int	DONT	Negotiation: Dont do option
protected static final int	EC	Erase Char
protected static final int	ECHO	Telnet Option: ECHO
protected static final int	EL	Erase Line
protected static final int	ENCRYPT
protected static final int	EXT_ASCII	Unused
protected static final int	GA	Go Ahead Newer Telnets do not make use of this option that allows a specific communication mode.
protected static final int	IAC	Interpret As Command
protected static final int	IP	Interrupt Process
protected static final int	IS	TTYPE subnegotiation: IS
protected static final int	LINEMODE	Telnet Option: Linemode
protected static final int	LM_EDIT
protected static final int	LM_FORWARDMASK
protected static final int	LM_MODE
protected static final int	LM_MODEACK	Following methods implement init/request/answer procedures for telnet protocol level communication.
protected static final int	LM_SLC
protected static final int	LM_SLC_ABORT	The following implement the NVT (network virtual terminal) which offers the concept of a simple "printer".
protected static final int	LM_SLC_ACK
protected static final int	LM_SLC_AO
protected static final int	LM_SLC_AYT
protected static final int	LM_SLC_BRK
protected static final int	LM_SLC_CANTCHANGE	Constants declaration
protected static final int	LM_SLC_DEFAULT
protected static final int	LM_SLC_EOF
protected static final int	LM_SLC_EOR
protected static final int	LM_SLC_FLUSHIN
protected static final int	LM_SLC_FLUSHOUT
protected static final int	LM_SLC_IP
protected static final int	LM_SLC_LEVELBITS
protected static final int	LM_SLC_NOSUPPORT
protected static final int	LM_SLC_SUSP
protected static final int	LM_SLC_SYNCH
protected static final int	LM_SLC_VALUE	End telnet protocol level communication methods
protected static final int	LM_TRAPSIG
protected static final int	LOGOUT	Telnet Option: Logout This allows nice goodbye to time-outed or unwanted clients.
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).
protected static final int	NE_ESC	The following options are options for which we also support subnegotiation based upon the telnet protocol specification.
protected static final int	NE_IN_END
protected static final int	NE_IN_ERROR
protected static final int	NE_INFO
protected static final int	NE_USERVAR
protected static final int	NE_VALUE
protected static final int	NE_VAR	The following are constants for supported options, which can be negotiated based upon the telnet protocol specification.
protected static final int	NE_VAR_DEFINED
protected static final int	NE_VAR_DEFINED_EMPTY
protected static final int	NE_VAR_NAME_MAXLENGTH
protected static final int	NE_VAR_OK
protected static final int	NE_VAR_UNDEFINED
protected static final int	NE_VAR_VALUE_MAXLENGTH
protected static final int	NEWENV	Telnet Option: Environment
protected static final int	NOP	No operation
protected static final int	SB	Marks start of a subnegotiation.
protected static final int	SE	Marks end of subnegotiation.
protected static final int	SEND	TTYPE subnegotiation: SEND
protected static final int	SEND_LOC
protected static final int	SUPGA	Telnet Option: SUPress Go Ahead This will be negotiated, all new telnet protocol implementations are recommended to do this.
protected static final int	TTYPE	Telnet Option: Terminal TYPE Server request contains subnegotiation SEND Client response contains subnegotiation with data IS,terminal type string
protected static final int	WILL	Negotiation: Will do option
protected static final int	WONT	Negotiation: Wont do option

Constructor Summary

Constructors

Constructor	Description
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 Summary

Modifier and Type	Method	Description
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.
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.
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(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 Details

IAC

protected static final int IAC

Interpret As Command

See Also:

• 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.

See Also:

• Constant Field Values

WILL

protected static final int WILL

Negotiation: Will do option

See Also:

• Constant Field Values

WONT

protected static final int WONT

Negotiation: Wont do option

See Also:

• Constant Field Values

DO

protected static final int DO

Negotiation: Do option

See Also:

• Constant Field Values

DONT

protected static final int DONT

Negotiation: Dont do option

See Also:

• Constant Field Values

SB

protected static final int SB

Marks start of a subnegotiation.

See Also:

• Constant Field Values

SE

protected static final int SE

Marks end of subnegotiation.

See Also:

• Constant Field Values

NOP

protected static final int NOP

No operation

See Also:

• 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?

See Also:

• Constant Field Values

BRK

protected static final int BRK

Break

See Also:

• Constant Field Values

IP

protected static final int IP

Interrupt Process

See Also:

• Constant Field Values

AO

protected static final int AO

Abort Output

See Also:

• Constant Field Values

AYT

protected static final int AYT

Are You There

See Also:

• Constant Field Values

EC

protected static final int EC

Erase Char

See Also:

• Constant Field Values

EL

protected static final int EL

Erase Line

See Also:

• Constant Field Values

ECHO

protected static final int ECHO

Telnet Option: ECHO

See Also:

• 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.

See Also:

• 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).

See Also:

• 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

See Also:

• Constant Field Values

IS

protected static final int IS

TTYPE subnegotiation: IS

See Also:

• Constant Field Values

SEND

protected static final int SEND

TTYPE subnegotiation: SEND

See Also:

• Constant Field Values

LOGOUT

protected static final int LOGOUT

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

See Also:

• Constant Field Values

LINEMODE

protected static final int LINEMODE

Telnet Option: Linemode

The infamous line mode option.

See Also:

• Constant Field Values

LM_MODE

protected static final int LM_MODE

See Also:

• Constant Field Values

LM_EDIT

protected static final int LM_EDIT

See Also:

• Constant Field Values

LM_TRAPSIG

protected static final int LM_TRAPSIG

See Also:

• Constant Field Values

LM_MODEACK

protected static final int LM_MODEACK

Following methods implement init/request/answer procedures for telnet protocol level communication.

See Also:

• Constant Field Values

LM_FORWARDMASK

protected static final int LM_FORWARDMASK

See Also:

• Constant Field Values

LM_SLC

protected static final int LM_SLC

See Also:

• Constant Field Values

LM_SLC_NOSUPPORT

protected static final int LM_SLC_NOSUPPORT

See Also:

• Constant Field Values

LM_SLC_DEFAULT

protected static final int LM_SLC_DEFAULT

See Also:

• Constant Field Values

LM_SLC_VALUE

protected static final int LM_SLC_VALUE

End telnet protocol level communication methods

See Also:

• Constant Field Values

LM_SLC_CANTCHANGE

protected static final int LM_SLC_CANTCHANGE

Constants declaration

See Also:

• Constant Field Values

LM_SLC_LEVELBITS

protected static final int LM_SLC_LEVELBITS

See Also:

• Constant Field Values

LM_SLC_ACK

protected static final int LM_SLC_ACK

See Also:

• Constant Field Values

LM_SLC_FLUSHIN

protected static final int LM_SLC_FLUSHIN

See Also:

• Constant Field Values

LM_SLC_FLUSHOUT

protected static final int LM_SLC_FLUSHOUT

See Also:

• Constant Field Values

LM_SLC_SYNCH

protected static final int LM_SLC_SYNCH

See Also:

• Constant Field Values

LM_SLC_BRK

protected static final int LM_SLC_BRK

See Also:

• Constant Field Values

LM_SLC_IP

protected static final int LM_SLC_IP

See Also:

• Constant Field Values

LM_SLC_AO

protected static final int LM_SLC_AO

See Also:

• Constant Field Values

LM_SLC_AYT

protected static final int LM_SLC_AYT

See Also:

• Constant Field Values

LM_SLC_EOR

protected static final int LM_SLC_EOR

See Also:

• Constant Field Values

LM_SLC_ABORT

protected static final int LM_SLC_ABORT

The following implement the NVT (network virtual terminal) which offers the concept of a simple "printer". They are the basical meanings of control possibilities on a standard telnet implementation.

See Also:

• Constant Field Values

LM_SLC_EOF

protected static final int LM_SLC_EOF

See Also:

• Constant Field Values

LM_SLC_SUSP

protected static final int LM_SLC_SUSP

See Also:

• Constant Field Values

NEWENV

protected static final int NEWENV

Telnet Option: Environment

See Also:

• Constant Field Values

NE_INFO

protected static final int NE_INFO

See Also:

• Constant Field Values

NE_VAR

protected static final int NE_VAR

The following are constants for supported options, which can be negotiated based upon the telnet protocol specification.

See Also:

• Constant Field Values

NE_VALUE

protected static final int NE_VALUE

See Also:

• Constant Field Values

NE_ESC

protected static final int NE_ESC

The following options are options for which we also support subnegotiation based upon the telnet protocol specification.

See Also:

• Constant Field Values

NE_USERVAR

protected static final int NE_USERVAR

See Also:

• Constant Field Values

NE_VAR_OK

protected static final int NE_VAR_OK

See Also:

• Constant Field Values

NE_VAR_DEFINED

protected static final int NE_VAR_DEFINED

See Also:

• Constant Field Values

NE_VAR_DEFINED_EMPTY

protected static final int NE_VAR_DEFINED_EMPTY

See Also:

• Constant Field Values

NE_VAR_UNDEFINED

protected static final int NE_VAR_UNDEFINED

See Also:

• Constant Field Values

NE_IN_ERROR

protected static final int NE_IN_ERROR

See Also:

• Constant Field Values

NE_IN_END

protected static final int NE_IN_END

See Also:

• Constant Field Values

NE_VAR_NAME_MAXLENGTH

protected static final int NE_VAR_NAME_MAXLENGTH

See Also:

• Constant Field Values

NE_VAR_VALUE_MAXLENGTH

protected static final int NE_VAR_VALUE_MAXLENGTH

See Also:

• Constant Field Values

EXT_ASCII

protected static final int EXT_ASCII

Unused

See Also:

• Constant Field Values

SEND_LOC

protected static final int SEND_LOC

See Also:

• Constant Field Values

AUTHENTICATION

protected static final int AUTHENTICATION

See Also:

• Constant Field Values

ENCRYPT

protected static final int ENCRYPT

See Also:

• Constant Field Values

Constructor Details

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 Details

initIO

public void initIO()
            throws IOException

Throws:

IOException

setConnection

public void setConnection(Connection con)

write

public void write(byte b)
           throws 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:

IOException - if an error occurs

write

public void write(int i)
           throws IOException

Method to output an int.

Parameters:

i - Integer to be written.

Throws:

IOException - if an error occurs

write

public void write(byte[] sequence)
           throws IOException

Method to write an array of bytes.

Parameters:

sequence - byte[] to be written.

Throws:

IOException - if an error occurs

write

public void write(int[] sequence)
           throws IOException

Method to output an array of int' s.

Parameters:

sequence - int [] to write

Throws:

IOException - if an error occurs

write

public void write(char ch)
           throws IOException

Method to write a char.

Parameters:

ch - char to be written.

Throws:

IOException - if an error occurs

write

public void write(String str)
           throws IOException

Method to output a string.

Parameters:

str - String to be written.

Throws:

IOException - if an error occurs

flush

public void flush()
           throws IOException

Method to flush all buffered output.

Throws:

IOException - if an error occurs

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 IOException

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

Returns:

int read from stream.

Throws:

IOException - if an error occurs

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)