TerminalTypeOptionHandler.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.telnet;

/**
 * Implements the telnet terminal type option RFC 1091.
 */
public class TerminalTypeOptionHandler extends TelnetOptionHandler {
    /**
     * Terminal type option
     */
    protected static final int TERMINAL_TYPE = 24;

    /**
     * Send (for subnegotiation)
     */
    protected static final int TERMINAL_TYPE_SEND = 1;

    /**
     * Is (for subnegotiation)
     */
    protected static final int TERMINAL_TYPE_IS = 0;

    /**
     * Terminal type
     */
    private final String termType;

    /**
     * Constructor for the TerminalTypeOptionHandler. Initial and accept behavior flags are set to false
     *
     * @param termtype - terminal type that will be negotiated.
     */
    public TerminalTypeOptionHandler(final String termtype) {
        super(TelnetOption.TERMINAL_TYPE, false, false, false, false);
        termType = termtype;
    }

    /**
     * Constructor for the TerminalTypeOptionHandler. Allows defining desired initial setting for local/remote activation of this option and behavior in case a
     * local/remote activation request for this option is received.
     *
     * @param termtype     - terminal type that will be negotiated.
     * @param initlocal    - if set to true, a {@code WILL} is sent upon connection.
     * @param initremote   - if set to true, a {@code DO} is sent upon connection.
     * @param acceptlocal  - if set to true, any {@code DO} request is accepted.
     * @param acceptremote - if set to true, any {@code WILL} request is accepted.
     */
    public TerminalTypeOptionHandler(final String termtype, final boolean initlocal, final boolean initremote, final boolean acceptlocal,
            final boolean acceptremote) {
        super(TelnetOption.TERMINAL_TYPE, initlocal, initremote, acceptlocal, acceptremote);
        termType = termtype;
    }

    /**
     * Implements the abstract method of TelnetOptionHandler.
     *
     * @param suboptionData   - the sequence received, without IAC SB & IAC SE
     * @param suboptionLength - the length of data in suboption_data
     * @return terminal type information
     */
    @Override
    public int[] answerSubnegotiation(final int suboptionData[], final int suboptionLength) {
        if (suboptionData != null && suboptionLength > 1 && termType != null) {
            if (suboptionData[0] == TERMINAL_TYPE && suboptionData[1] == TERMINAL_TYPE_SEND) {
                final int[] response = new int[termType.length() + 2];

                response[0] = TERMINAL_TYPE;
                response[1] = TERMINAL_TYPE_IS;

                for (int ii = 0; ii < termType.length(); ii++) {
                    response[ii + 2] = termType.charAt(ii);
                }

                return response;
            }
        }
        return null;
    }
}