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     *
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        for ( // 2 //
118                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}