    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.net.telnet;
    019
    020/**
    021 * Implements the Telnet window size option RFC 1073.
    022 *
    023 * @since 2.0
    024 */
    025public class WindowSizeOptionHandler extends TelnetOptionHandler {
    026    /**
    027     * Window size option
    028     */
    029    protected static final int WINDOW_SIZE = 31;
    030
    031    /**
    032     * Horizontal Size
    033     */
    034    private int width = 80;
    035
    036    /**
    037     * Vertical Size
    038     */
    039    private int height = 24;
    040
    041    /**
    042     * Constructor for the WindowSizeOptionHandler. Initial and accept behavior flags are set to false
    043     *
    044     * @param nWidth    Window width.
    045     * @param nHeight   Window Height
    046     */
    047    public WindowSizeOptionHandler(final int nWidth, final int nHeight) {
    048        super(TelnetOption.WINDOW_SIZE, false, false, false, false);
    049
    050        width = nWidth;
    051        height = nHeight;
    052    }
    053
    054    /**
    055     * Constructor for the WindowSizeOptionHandler. Allows defining desired initial setting for local/remote activation of this option and behavior in case a
    056     * local/remote activation request for this option is received.
    057     *
    058     * @param nWidth         Window width.
    059     * @param nHeight        Window Height
    060     * @param initlocal      if set to true, a {@code WILL} is sent upon connection.
    061     * @param initremote     if set to true, a {@code DO} is sent upon connection.
    062     * @param acceptlocal    if set to true, any {@code DO} request is accepted.
    063     * @param acceptremote   if set to true, any {@code WILL} request is accepted.
    064     */
    065    public WindowSizeOptionHandler(final int nWidth, final int nHeight, final boolean initlocal, final boolean initremote, final boolean acceptlocal,
    066            final boolean acceptremote) {
    067        super(TelnetOption.WINDOW_SIZE, initlocal, initremote, acceptlocal, acceptremote);
    068
    069        width = nWidth;
    070        height = nHeight;
    071    }
    072
    073    /**
    074     * Implements the abstract method of TelnetOptionHandler. This will send the client Height and Width to the server.
    075     *
    076     * @return array to send to remote system
    077     */
    078    @Override
    079    public int[] startSubnegotiationLocal() {
    080        final int nCompoundWindowSize = width * 0x10000 + height;
    081        int nResponseSize = 5;
    082        int nIndex;
    083        int nShift;
    084        int nTurnedOnBits;
    085
    086        if (width % 0x100 == 0xFF) {
    087            nResponseSize += 1;
    088        }
    089
    090        if (width / 0x100 == 0xFF) {
    091            nResponseSize += 1;
    092        }
    093
    094        if (height % 0x100 == 0xFF) {
    095            nResponseSize += 1;
    096        }
    097
    098        if (height / 0x100 == 0xFF) {
    099            nResponseSize += 1;
    100        }
    101
    102        //
    103        // allocate response array
    104        //
    105        final int[] response = new int[nResponseSize];
    106
    107        //
    108        // Build response array.
    109        // ---------------------
    110        // 1. put option name.
    111        // 2. loop through Window size and fill the values,
    112        // 3. duplicate 'ff' if needed.
    113        //
    114
    115        response[0] = WINDOW_SIZE; // 1 //
    116
    117        // 2 //
    118        for (nIndex = 1, nShift = 24; nIndex < nResponseSize; nIndex++, nShift -= 8) {
    119            nTurnedOnBits = 0xFF;
    120            nTurnedOnBits <<= nShift;
    121            response[nIndex] = (nCompoundWindowSize & nTurnedOnBits) >>> nShift;
    122
    123            if (response[nIndex] == 0xff) { // 3 //
    124                nIndex++;
    125                response[nIndex] = 0xff;
    126            }
    127        }
    128
    129        return response;
    130    }
    131
    132}