TelnetClientExample.java
/*
* 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.examples.telnet;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.charset.Charset;
import java.time.Duration;
import java.util.StringTokenizer;
import org.apache.commons.net.telnet.EchoOptionHandler;
import org.apache.commons.net.telnet.InvalidTelnetOptionException;
import org.apache.commons.net.telnet.SimpleOptionHandler;
import org.apache.commons.net.telnet.SuppressGAOptionHandler;
import org.apache.commons.net.telnet.TelnetClient;
import org.apache.commons.net.telnet.TelnetNotificationHandler;
import org.apache.commons.net.telnet.TerminalTypeOptionHandler;
/**
* This is a simple example of use of TelnetClient. An external option handler (SimpleTelnetOptionHandler) is used. Initial configuration requested by
* TelnetClient will be: WILL ECHO, WILL SUPPRESS-GA, DO SUPPRESS-GA. VT100 terminal type will be subnegotiated.
* <p>
* Also, use of the sendAYT(), getLocalOptionState(), getRemoteOptionState() is demonstrated. When connected, type AYT to send an AYT command to the server and
* see the result. Type OPT to see a report of the state of the first 25 options.
*/
public class TelnetClientExample implements Runnable, TelnetNotificationHandler {
private static TelnetClient tc;
/**
* Main for the TelnetClientExample.
*
* @param args input params
* @throws Exception on error
*/
public static void main(final String[] args) throws Exception {
FileOutputStream fout = null;
if (args.length < 1) {
System.err.println("Usage: TelnetClientExample <remote-ip> [<remote-port>]");
System.exit(1);
}
final String remoteip = args[0];
final int remoteport;
if (args.length > 1) {
remoteport = Integer.parseInt(args[1]);
} else {
remoteport = 23;
}
try {
fout = new FileOutputStream("spy.log", true);
} catch (final IOException e) {
System.err.println("Exception while opening the spy file: " + e.getMessage());
}
tc = new TelnetClient();
final TerminalTypeOptionHandler ttopt = new TerminalTypeOptionHandler("VT100", false, false, true, false);
final EchoOptionHandler echoopt = new EchoOptionHandler(true, false, true, false);
final SuppressGAOptionHandler gaopt = new SuppressGAOptionHandler(true, true, true, true);
try {
tc.addOptionHandler(ttopt);
tc.addOptionHandler(echoopt);
tc.addOptionHandler(gaopt);
} catch (final InvalidTelnetOptionException e) {
System.err.println("Error registering option handlers: " + e.getMessage());
}
while (true) {
boolean end_loop = false;
try {
tc.connect(remoteip, remoteport);
final Thread reader = new Thread(new TelnetClientExample());
tc.registerNotifHandler(new TelnetClientExample());
System.out.println("TelnetClientExample");
System.out.println("Type AYT to send an AYT telnet command");
System.out.println("Type OPT to print a report of status of options (0-24)");
System.out.println("Type REGISTER to register a new SimpleOptionHandler");
System.out.println("Type UNREGISTER to unregister an OptionHandler");
System.out.println("Type SPY to register the spy (connect to port 3333 to spy)");
System.out.println("Type UNSPY to stop spying the connection");
System.out.println("Type ^[A-Z] to send the control character; use ^^ to send ^");
reader.start();
final OutputStream outstr = tc.getOutputStream();
final byte[] buff = new byte[1024];
int readCount = 0;
do {
try {
readCount = System.in.read(buff);
if (readCount > 0) {
final Charset charset = Charset.defaultCharset();
final String line = new String(buff, 0, readCount, charset); // deliberate use of default charset
if (line.startsWith("AYT")) {
try {
System.out.println("Sending AYT");
System.out.println("AYT response:" + tc.sendAYT(Duration.ofSeconds(5)));
} catch (final IOException e) {
System.err.println("Exception waiting AYT response: " + e.getMessage());
}
} else if (line.startsWith("OPT")) {
System.out.println("Status of options:");
for (int ii = 0; ii < 25; ii++) {
System.out.println("Local Option " + ii + ":" + tc.getLocalOptionState(ii) + " Remote Option " + ii + ":"
+ tc.getRemoteOptionState(ii));
}
} else if (line.startsWith("REGISTER")) {
final StringTokenizer st = new StringTokenizer(new String(buff, charset));
try {
st.nextToken();
final int opcode = Integer.parseInt(st.nextToken());
final boolean initlocal = Boolean.parseBoolean(st.nextToken());
final boolean initremote = Boolean.parseBoolean(st.nextToken());
final boolean acceptlocal = Boolean.parseBoolean(st.nextToken());
final boolean acceptremote = Boolean.parseBoolean(st.nextToken());
final SimpleOptionHandler opthand = new SimpleOptionHandler(opcode, initlocal, initremote, acceptlocal, acceptremote);
tc.addOptionHandler(opthand);
} catch (final Exception e) {
if (e instanceof InvalidTelnetOptionException) {
System.err.println("Error registering option: " + e.getMessage());
} else {
System.err.println("Invalid REGISTER command.");
System.err.println("Use REGISTER optcode initlocal initremote acceptlocal acceptremote");
System.err.println("(optcode is an integer.)");
System.err.println("(initlocal, initremote, acceptlocal, acceptremote are boolean)");
}
}
} else if (line.startsWith("UNREGISTER")) {
final StringTokenizer st = new StringTokenizer(new String(buff, charset));
try {
st.nextToken();
final int opcode = Integer.parseInt(st.nextToken());
tc.deleteOptionHandler(opcode);
} catch (final Exception e) {
if (e instanceof InvalidTelnetOptionException) {
System.err.println("Error unregistering option: " + e.getMessage());
} else {
System.err.println("Invalid UNREGISTER command.");
System.err.println("Use UNREGISTER optcode");
System.err.println("(optcode is an integer)");
}
}
} else if (line.startsWith("SPY")) {
tc.registerSpyStream(fout);
} else if (line.startsWith("UNSPY")) {
tc.stopSpyStream();
} else if (line.matches("^\\^[A-Z^]\\r?\\n?$")) {
final byte toSend = buff[1];
if (toSend == '^') {
outstr.write(toSend);
} else {
outstr.write(toSend - 'A' + 1);
}
outstr.flush();
} else {
try {
outstr.write(buff, 0, readCount);
outstr.flush();
} catch (final IOException e) {
end_loop = true;
}
}
}
} catch (final IOException e) {
System.err.println("Exception while reading keyboard:" + e.getMessage());
end_loop = true;
}
} while (readCount > 0 && !end_loop);
try {
tc.disconnect();
} catch (final IOException e) {
System.err.println("Exception while connecting:" + e.getMessage());
}
} catch (final IOException e) {
System.err.println("Exception while connecting:" + e.getMessage());
System.exit(1);
}
}
}
/**
* Callback method called when TelnetClient receives an option negotiation command.
*
* @param negotiation_code - type of negotiation command received (RECEIVED_DO, RECEIVED_DONT, RECEIVED_WILL, RECEIVED_WONT, RECEIVED_COMMAND)
* @param option_code - code of the option negotiated
*/
@Override
public void receivedNegotiation(final int negotiation_code, final int option_code) {
String command;
switch (negotiation_code) {
case TelnetNotificationHandler.RECEIVED_DO:
command = "DO";
break;
case TelnetNotificationHandler.RECEIVED_DONT:
command = "DONT";
break;
case TelnetNotificationHandler.RECEIVED_WILL:
command = "WILL";
break;
case TelnetNotificationHandler.RECEIVED_WONT:
command = "WONT";
break;
case TelnetNotificationHandler.RECEIVED_COMMAND:
command = "COMMAND";
break;
default:
command = Integer.toString(negotiation_code); // Should not happen
break;
}
System.out.println("Received " + command + " for option code " + option_code);
}
/**
* Reader thread: Reads lines from the TelnetClient and echoes them on the screen.
*/
@Override
public void run() {
final InputStream instr = tc.getInputStream();
try {
final byte[] buff = new byte[1024];
int readCount = 0;
do {
readCount = instr.read(buff);
if (readCount > 0) {
System.out.print(new String(buff, 0, readCount, Charset.defaultCharset()));
}
} while (readCount >= 0);
} catch (final IOException e) {
System.err.println("Exception while reading socket:" + e.getMessage());
}
try {
tc.disconnect();
} catch (final IOException e) {
System.err.println("Exception while closing telnet:" + e.getMessage());
}
}
}