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