com.dalsemi.shell.server
Class Session

java.lang.Object
  |
  +--java.lang.Thread
        |
        +--com.dalsemi.shell.server.Session

Direct Known Subclasses:

FTPSession, SerialSession, TelnetSession

public abstract class Session

extends Thread

A session represents a single connection to the TINI system shell. When someone attempts to login, a server object spins off a session (an implementation of this class) to handle the communication. The session allows you to log into the system, then processes all system requests. Sessions are designed to be multi-threaded, allowing multiple simultaneous connections.

Inner Class Summary

protected class

Session.Login Encapsulates all of the information needed to log a user into the system.

Field Summary

protected String[]	commandHistory A list of the last few commands issued in this session.
static String	CURRENT_COMMAND The key used to index the current command in system environments.
static String	CURRENT_DIRECTORY The key used to index the current directory in system environments.
protected int	currentCommand Marks the beginning of the commandHistory buffer.
protected Hashtable	environment The environment associated with this session.
protected SystemPrintStream	err The error stream of the remote connection.
protected SystemInputStream	in The input stream of the remote connection.
protected boolean	inCommand Specifies that a command is currently being processed by this session.
protected int	lastCommand Marks the end of the commandHistory buffer.
protected Vector	loginStack The list of users that are currently logged into this session.
protected Object	myThreadID The thread ID of this session.
protected SystemPrintStream	out The output stream of the remote connection.
protected Object[]	paramsArray Used as temporary storage when parsing the parameters for a command.
protected Vector	paramsVector Used as temporary storage when parsing the parameters for a command.
protected String	password The password for the user that is currently logged in.
protected byte[]	prompt The text used as the command line prompt for this session.
static String	PROMPT The basic prompt displayed at the command line.
protected Object[]	retArray Used as temporary storage when parsing the parameters for a command.
protected Server	server The server that created this session.
protected boolean	shutdown Specifies that the session should attempt to close the connection after it has finished processing the current request.
protected String	userName The user that is currently logged in with this session.
static String	welcomeMessage The message shown to all users when they login to this session.

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

protected

Session(SystemInputStream in, SystemPrintStream out, SystemPrintStream err, Server server) Intializes the session.

Method Summary

void	addToHistory(String str) Adds a new command to the history buffer.
void	broadcast(String sendThis) Displays a message in this session.
protected abstract void	currentCommandFinished() Notifies this session that the current command has completed.
void	endSession() Cleans up the resources used by this session.
protected abstract void	exceptionThrown(Exception ex) Notifies this session that exception was thrown when executing a command.
protected void	execute(String commandStr) Executes the given command in the current shell.
void	forceEndSession() Notifies the server this session is ending and forces the session to terminate.
Hashtable	getEnvironment() Gets a reference to the current environment.
PrintStream	getErrStream() Gets the stream this session uses for error notification and critical messages.
String	getFromEnvironment(String key) Gets the value of the key from the current environment.
String	getHistoryNumber(int number) Gets the command at the given index of the command history.
String	getNextCommand() Gets the next command from this session's input stream.
PrintStream	getOutputStream() Gets the stream this session uses for output.
static Object[]	getParams(String str) Parses the command line into individual elements.
String	getUserName() Returns the user name associated with this session.
boolean	inCommand() Indicates whether this session is executing a shell command.
protected abstract void	login() Logs a user into the system.
protected void	parseLogin() Parses and executes the ".login" file for the current user.
void	printHistory(PrintStream out) Prints the list of commands stored in the history buffer of this session.
void	run() Starts the communication loop of the session.
protected abstract void	sessionEnding() Cleans up any resources associated with this session when it terminates.
String	stepDownHistory() Moves the current position in the history buffer down one and returns the command at that position.
String	stepUpHistory() Moves the current position in the history buffer up one and returns the command at that position.
boolean	su(String userName, String password) Allows the current user to login as another user.
void	updatePrompt(String withThis) Notifies this session of a directory change.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getName, getPriority, getThreadGroup, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setDaemon, setName, setPriority, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

in

protected SystemInputStream in

The input stream of the remote connection.

out

protected SystemPrintStream out

The output stream of the remote connection.

err

protected SystemPrintStream err

The error stream of the remote connection.

inCommand

protected boolean inCommand

Specifies that a command is currently being processed by this session.

environment

protected Hashtable environment

The environment associated with this session.

shutdown

protected boolean shutdown

Specifies that the session should attempt to close the connection after it has finished processing the current request.

commandHistory

protected String[] commandHistory

A list of the last few commands issued in this session. This list is implemented as a circular buffer.

lastCommand

protected int lastCommand

Marks the end of the commandHistory buffer.

currentCommand

protected int currentCommand

Marks the beginning of the commandHistory buffer.

prompt

protected byte[] prompt

The text used as the command line prompt for this session.

server

protected Server server

The server that created this session.

userName

protected String userName

The user that is currently logged in with this session.

password

protected String password

The password for the user that is currently logged in.

loginStack

protected Vector loginStack

The list of users that are currently logged into this session.

myThreadID

protected Object myThreadID

The thread ID of this session.

paramsVector

protected Vector paramsVector

Used as temporary storage when parsing the parameters for a command.

paramsArray

protected Object[] paramsArray

Used as temporary storage when parsing the parameters for a command.

retArray

protected Object[] retArray

Used as temporary storage when parsing the parameters for a command.

CURRENT_DIRECTORY

public static String CURRENT_DIRECTORY

The key used to index the current directory in system environments.

CURRENT_COMMAND

public static String CURRENT_COMMAND

The key used to index the current command in system environments.

PROMPT

public static String PROMPT

The basic prompt displayed at the command line.

welcomeMessage

public static String welcomeMessage

The message shown to all users when they login to this session.

Constructor Detail

Session

protected Session(SystemInputStream in,
                  SystemPrintStream out,
                  SystemPrintStream err,
                  Server server)

Intializes the session.

Parameters:

in - stream this session should use to get data from user

out - stream this session should use to output to user

err - stream this session should use to output errors to user

server - the server in charge of this session

Method Detail

getUserName

public String getUserName()

Returns the user name associated with this session.

Returns:

the current user's name

login

protected abstract void login()
                       throws IOException

Logs a user into the system. This method is responsible for identifying and verifying the user. Typically this is done with a user name and password.

run

public final void run()

Starts the communication loop of the session. First the login() method is called. If the user is sucessfully logged into the system, commands are accepted and processed until the session is terminated.

Overrides:

run in class Thread

execute

protected void execute(String commandStr)

Executes the given command in the current shell. The commandStr parameter can contain any number of elements. These elements will be separated into String[] for the command interpreter.

Parameters:

commandStr - full command line to execute

getErrStream

public PrintStream getErrStream()

Gets the stream this session uses for error notification and critical messages.

Returns:

the session's PrintStream used for errors

getOutputStream

public PrintStream getOutputStream()

Gets the stream this session uses for output.

Returns:

the session's PrintStream

forceEndSession

public final void forceEndSession()

Notifies the server this session is ending and forces the session to terminate. This is used when some error has occurred that the session and server do not know how to handle.

endSession

public final void endSession()

Cleans up the resources used by this session.

su

public boolean su(String userName,
                  String password)

Allows the current user to login as another user. The old user's identity is added to a login stack. Once the new user terminates their session, the old user idenity is resumed.

Parameters:

userName - new user's name

password - new user's password

Returns:

true if login was successful, false otherwise

currentCommandFinished

protected abstract void currentCommandFinished()

Notifies this session that the current command has completed. For example, the user types "ls". The command is received and parsed, then the appropriate command is called in the shell. Finally, this session may need to again display the system prompt or perform other session-specific functions. Only call this from a synchronized block!!!

sessionEnding

protected abstract void sessionEnding()

Cleans up any resources associated with this session when it terminates.

exceptionThrown

protected abstract void exceptionThrown(Exception ex)

Notifies this session that exception was thrown when executing a command. This method will attempt to notify the user. Any exceptions raised specifically by shell commands should try to give as descriptive a message to the exception as possible.

Parameters:

ex - the exception thrown

getParams

public static Object[] getParams(String str)

Parses the command line into individual elements. The parser will use whitespace characters and quotes as delimiters.

Parameters:

str - complete command line

Returns:

an object array that contains the String command in the first element, and a String[] of the arguments to that command in the second element

getNextCommand

public String getNextCommand()
                      throws IOException

Gets the next command from this session's input stream. This effectively performs a readLine(), but gives this session a chance to parse the incoming data for special characters and commands.

Returns:

the next command from the input stream

getEnvironment

public Hashtable getEnvironment()

Gets a reference to the current environment.

Returns:

the current environment as a Hashtable

getFromEnvironment

public String getFromEnvironment(String key)

Gets the value of the key from the current environment.

Parameters:

key - name of desired environment variable

Returns:

the value specified by the given key, or null if that key does not exist in the environment

addToHistory

public void addToHistory(String str)

Adds a new command to the history buffer.

Parameters:

str - command to add to the history

stepUpHistory

public String stepUpHistory()

Moves the current position in the history buffer up one and returns the command at that position.

Returns:

the command one up from the current position in the history buffer

stepDownHistory

public String stepDownHistory()

Moves the current position in the history buffer down one and returns the command at that position.

Returns:

the command one down from the current position in the history buffer

getHistoryNumber

public String getHistoryNumber(int number)

Gets the command at the given index of the command history.

Parameters:

number - index into the history cache.

Returns:

the command specified by the given number

printHistory

public void printHistory(PrintStream out)

Prints the list of commands stored in the history buffer of this session.

Parameters:

out - stream used to print the history

inCommand

public boolean inCommand()

Indicates whether this session is executing a shell command.

Returns:

true if the session is executing a shell command

updatePrompt

public void updatePrompt(String withThis)

Notifies this session of a directory change. This allows the command line prompt to reflect the change.

Parameters:

withThis - the new directory name

broadcast

public void broadcast(String sendThis)

Displays a message in this session. This functionality may be disabled by setting the environment variable "BROADCASTS" to "false".

Parameters:

sendThis - message to display

parseLogin

protected void parseLogin()

Parses and executes the ".login" file for the current user. First, the current directory is searched for a directory that matches the user's name. If one is found, it becomes the current directory. The user's home directory is also set to this location. Next, that directory is checked for the existance of a ".login" file. If one is found, the file is executed using the "source" command.