org.apache.commons.net.telnet.TelnetClient Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.net.telnet;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/***
* The TelnetClient class implements the simple network virtual
* terminal (NVT) for the Telnet protocol according to RFC 854. It
* does not implement any of the extra Telnet options because it
* is meant to be used within a Java program providing automated
* access to Telnet accessible resources.
*
* The class can be used by first connecting to a server using the
* SocketClient
* {@link org.apache.commons.net.SocketClient#connect connect}
* method. Then an InputStream and OutputStream for sending and
* receiving data over the Telnet connection can be obtained by
* using the {@link #getInputStream getInputStream() } and
* {@link #getOutputStream getOutputStream() } methods.
* When you finish using the streams, you must call
* {@link #disconnect disconnect } rather than simply
* closing the streams.
***/
public class TelnetClient extends Telnet
{
private InputStream __input;
private OutputStream __output;
protected boolean readerThread = true;
private TelnetInputListener inputListener;
/***
* Default TelnetClient constructor, sets terminal-type {@code VT100}.
***/
public TelnetClient()
{
/* TERMINAL-TYPE option (start)*/
super ("VT100");
/* TERMINAL-TYPE option (end)*/
__input = null;
__output = null;
}
/**
* Construct an instance with the specified terminal type.
*
* @param termtype the terminal type to use, e.g. {@code VT100}
*/
/* TERMINAL-TYPE option (start)*/
public TelnetClient(String termtype)
{
super (termtype);
__input = null;
__output = null;
}
/* TERMINAL-TYPE option (end)*/
void _flushOutputStream() throws IOException
{
_output_.flush();
}
void _closeOutputStream() throws IOException
{
_output_.close();
}
/***
* Handles special connection requirements.
*
* @exception IOException If an error occurs during connection setup.
***/
@Override
protected void _connectAction_() throws IOException
{
super._connectAction_();
TelnetInputStream tmp = new TelnetInputStream(_input_, this, readerThread);
if(readerThread)
{
tmp._start();
}
// __input CANNOT refer to the TelnetInputStream. We run into
// blocking problems when some classes use TelnetInputStream, so
// we wrap it with a BufferedInputStream which we know is safe.
// This blocking behavior requires further investigation, but right
// now it looks like classes like InputStreamReader are not implemented
// in a safe manner.
__input = new BufferedInputStream(tmp);
__output = new TelnetOutputStream(this);
}
/***
* Disconnects the telnet session, closing the input and output streams
* as well as the socket. If you have references to the
* input and output streams of the telnet connection, you should not
* close them yourself, but rather call disconnect to properly close
* the connection.
***/
@Override
public void disconnect() throws IOException
{
if (__input != null) {
__input.close();
}
if (__output != null) {
__output.close();
}
super.disconnect();
}
/***
* Returns the telnet connection output stream. You should not close the
* stream when you finish with it. Rather, you should call
* {@link #disconnect disconnect }.
*
* @return The telnet connection output stream.
***/
public OutputStream getOutputStream()
{
return __output;
}
/***
* Returns the telnet connection input stream. You should not close the
* stream when you finish with it. Rather, you should call
* {@link #disconnect disconnect }.
*
* @return The telnet connection input stream.
***/
public InputStream getInputStream()
{
return __input;
}
/***
* Returns the state of the option on the local side.
*
* @param option - Option to be checked.
*
* @return The state of the option on the local side.
***/
public boolean getLocalOptionState(int option)
{
/* BUG (option active when not already acknowledged) (start)*/
return (_stateIsWill(option) && _requestedWill(option));
/* BUG (option active when not already acknowledged) (end)*/
}
/***
* Returns the state of the option on the remote side.
*
* @param option - Option to be checked.
*
* @return The state of the option on the remote side.
***/
public boolean getRemoteOptionState(int option)
{
/* BUG (option active when not already acknowledged) (start)*/
return (_stateIsDo(option) && _requestedDo(option));
/* BUG (option active when not already acknowledged) (end)*/
}
/* open TelnetOptionHandler functionality (end)*/
/* Code Section added for supporting AYT (start)*/
/***
* Sends an Are You There sequence and waits for the result.
*
* @param timeout - Time to wait for a response (millis.)
*
* @return true if AYT received a response, false otherwise
*
* @throws InterruptedException on error
* @throws IllegalArgumentException on error
* @throws IOException on error
***/
public boolean sendAYT(long timeout)
throws IOException, IllegalArgumentException, InterruptedException
{
return (_sendAYT(timeout));
}
/* Code Section added for supporting AYT (start)*/
/***
* Sends a protocol-specific subnegotiation message to the remote peer.
* {@link TelnetClient} will add the IAC SB & IAC SE framing bytes;
* the first byte in {@code message} should be the appropriate telnet
* option code.
*
*
* This method does not wait for any response. Subnegotiation messages
* sent by the remote end can be handled by registering an approrpriate
* {@link TelnetOptionHandler}.
*
*
* @param message option code followed by subnegotiation payload
* @throws IllegalArgumentException if {@code message} has length zero
* @throws IOException if an I/O error occurs while writing the message
* @since 3.0
***/
public void sendSubnegotiation(int[] message)
throws IOException, IllegalArgumentException
{
if (message.length < 1) {
throw new IllegalArgumentException("zero length message");
}
_sendSubnegotiation(message);
}
/***
* Sends a command byte to the remote peer, adding the IAC prefix.
*
*
* This method does not wait for any response. Messages
* sent by the remote end can be handled by registering an approrpriate
* {@link TelnetOptionHandler}.
*
*
* @param command the code for the command
* @throws IOException if an I/O error occurs while writing the message
* @throws IllegalArgumentException on error
* @since 3.0
***/
public void sendCommand(byte command)
throws IOException, IllegalArgumentException
{
_sendCommand(command);
}
/* open TelnetOptionHandler functionality (start)*/
/***
* Registers a new TelnetOptionHandler for this telnet client to use.
*
* @param opthand - option handler to be registered.
*
* @throws InvalidTelnetOptionException on error
* @throws IOException on error
***/
@Override
public void addOptionHandler(TelnetOptionHandler opthand)
throws InvalidTelnetOptionException, IOException
{
super.addOptionHandler(opthand);
}
/* open TelnetOptionHandler functionality (end)*/
/***
* Unregisters a TelnetOptionHandler.
*
* @param optcode - Code of the option to be unregistered.
*
* @throws InvalidTelnetOptionException on error
* @throws IOException on error
***/
@Override
public void deleteOptionHandler(int optcode)
throws InvalidTelnetOptionException, IOException
{
super.deleteOptionHandler(optcode);
}
/* Code Section added for supporting spystreams (start)*/
/***
* Registers an OutputStream for spying what's going on in
* the TelnetClient session.
*
* @param spystream - OutputStream on which session activity
* will be echoed.
***/
public void registerSpyStream(OutputStream spystream)
{
super._registerSpyStream(spystream);
}
/***
* Stops spying this TelnetClient.
*
***/
public void stopSpyStream()
{
super._stopSpyStream();
}
/* Code Section added for supporting spystreams (end)*/
/***
* Registers a notification handler to which will be sent
* notifications of received telnet option negotiation commands.
*
* @param notifhand - TelnetNotificationHandler to be registered
***/
@Override
public void registerNotifHandler(TelnetNotificationHandler notifhand)
{
super.registerNotifHandler(notifhand);
}
/***
* Unregisters the current notification handler.
*
***/
@Override
public void unregisterNotifHandler()
{
super.unregisterNotifHandler();
}
/***
* Sets the status of the reader thread.
*
*
* When enabled, a seaparate internal reader thread is created for new
* connections to read incoming data as it arrives. This results in
* immediate handling of option negotiation, notifications, etc.
* (at least until the fixed-size internal buffer fills up).
* Otherwise, no thread is created an all negotiation and option
* handling is deferred until a read() is performed on the
* {@link #getInputStream input stream}.
*
*
*
* The reader thread must be enabled for {@link TelnetInputListener}
* support.
*
*
*
* When this method is invoked, the reader thread status will apply to all
* subsequent connections; the current connection (if any) is not affected.
*
*
* @param flag true to enable the reader thread, false to disable
* @see #registerInputListener
***/
public void setReaderThread(boolean flag)
{
readerThread = flag;
}
/***
* Gets the status of the reader thread.
*
* @return true if the reader thread is enabled, false otherwise
***/
public boolean getReaderThread()
{
return (readerThread);
}
/***
* Register a listener to be notified when new incoming data is
* available to be read on the {@link #getInputStream input stream}.
* Only one listener is supported at a time.
*
*
* More precisely, notifications are issued whenever the number of
* bytes available for immediate reading (i.e., the value returned
* by {@link InputStream#available}) transitions from zero to non-zero.
* Note that (in general) multiple reads may be required to empty the
* buffer and reset this notification, because incoming bytes are being
* added to the internal buffer asynchronously.
*
*
*
* Notifications are only supported when a {@link #setReaderThread
* reader thread} is enabled for the connection.
*
*
* @param listener listener to be registered; replaces any previous
* @since 3.0
***/
public synchronized void registerInputListener(TelnetInputListener listener)
{
this.inputListener = listener;
}
/***
* Unregisters the current {@link TelnetInputListener}, if any.
*
* @since 3.0
***/
public synchronized void unregisterInputListener()
{
this.inputListener = null;
}
// Notify input listener
void notifyInputListener() {
TelnetInputListener listener;
synchronized (this) {
listener = this.inputListener;
}
if (listener != null) {
listener.telnetInputAvailable();
}
}
}