    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 *      http://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     * <p>
    044     *
    045     * @param nWidth  - Window width.
    046     * @param nHeight - Window Height
    047     */
    048    public WindowSizeOptionHandler(final int nWidth, final int nHeight) {
    049        super(TelnetOption.WINDOW_SIZE, false, false, false, false);
    050
    051        width = nWidth;
    052        height = nHeight;
    053    }
    054
    055    /**
    056     * Constructor for the WindowSizeOptionHandler. Allows defining desired initial setting for local/remote activation of this option and behavior in case a
    057     * local/remote activation request for this option is received.
    058     * <p>
    059     *
    060     * @param nWidth       - Window width.
    061     * @param nHeight      - Window Height
    062     * @param initlocal    - if set to true, a WILL is sent upon connection.
    063     * @param initremote   - if set to true, a DO is sent upon connection.
    064     * @param acceptlocal  - if set to true, any DO request is accepted.
    065     * @param acceptremote - if set to true, any WILL request is accepted.
    066     */
    067    public WindowSizeOptionHandler(final int nWidth, final int nHeight, final boolean initlocal, final boolean initremote, final boolean acceptlocal,
    068            final boolean acceptremote) {
    069        super(TelnetOption.WINDOW_SIZE, initlocal, initremote, acceptlocal, acceptremote);
    070
    071        width = nWidth;
    072        height = nHeight;
    073    }
    074
    075    /**
    076     * Implements the abstract method of TelnetOptionHandler. This will send the client Height and Width to the server.
    077     * <p>
    078     *
    079     * @return array to send to remote system
    080     */
    081    @Override
    082    public int[] startSubnegotiationLocal() {
    083        final int nCompoundWindowSize = width * 0x10000 + height;
    084        int nResponseSize = 5;
    085        int nIndex;
    086        int nShift;
    087        int nTurnedOnBits;
    088
    089        if (width % 0x100 == 0xFF) {
    090            nResponseSize += 1;
    091        }
    092
    093        if (width / 0x100 == 0xFF) {
    094            nResponseSize += 1;
    095        }
    096
    097        if (height % 0x100 == 0xFF) {
    098            nResponseSize += 1;
    099        }
    100
    101        if (height / 0x100 == 0xFF) {
    102            nResponseSize += 1;
    103        }
    104
    105        //
    106        // allocate response array
    107        //
    108        final int response[] = new int[nResponseSize];
    109
    110        //
    111        // Build response array.
    112        // ---------------------
    113        // 1. put option name.
    114        // 2. loop through Window size and fill the values,
    115        // 3. duplicate 'ff' if needed.
    116        //
    117
    118        response[0] = WINDOW_SIZE; // 1 //
    119
    120        for ( // 2 //
    121                nIndex = 1, nShift = 24; nIndex < nResponseSize; nIndex++, nShift -= 8) {
    122            nTurnedOnBits = 0xFF;
    123            nTurnedOnBits <<= nShift;
    124            response[nIndex] = (nCompoundWindowSize & nTurnedOnBits) >>> nShift;
    125
    126            if (response[nIndex] == 0xff) { // 3 //
    127                nIndex++;
    128                response[nIndex] = 0xff;
    129            }
    130        }
    131
    132        return response;
    133    }
    134
    135}