1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.net.telnet;
19
20 /**
21 * Implements the telnet window size option RFC 1073.
22 *
23 * @since 2.0
24 */
25 public class WindowSizeOptionHandler extends TelnetOptionHandler {
26 /**
27 * Window size option
28 */
29 protected static final int WINDOW_SIZE = 31;
30
31 /**
32 * Horizontal Size
33 */
34 private int width = 80;
35
36 /**
37 * Vertical Size
38 */
39 private int height = 24;
40
41 /**
42 * Constructor for the WindowSizeOptionHandler. Initial and accept behavior flags are set to false
43 *
44 * @param nWidth - Window width.
45 * @param nHeight - Window Height
46 */
47 public WindowSizeOptionHandler(final int nWidth, final int nHeight) {
48 super(TelnetOption.WINDOW_SIZE, false, false, false, false);
49
50 width = nWidth;
51 height = nHeight;
52 }
53
54 /**
55 * Constructor for the WindowSizeOptionHandler. Allows defining desired initial setting for local/remote activation of this option and behavior in case a
56 * local/remote activation request for this option is received.
57 * <p>
58 *
59 * @param nWidth - Window width.
60 * @param nHeight - Window Height
61 * @param initlocal - if set to true, a {@code WILL} is sent upon connection.
62 * @param initremote - if set to true, a {@code DO} is sent upon connection.
63 * @param acceptlocal - if set to true, any {@code DO} request is accepted.
64 * @param acceptremote - if set to true, any {@code WILL} request is accepted.
65 */
66 public WindowSizeOptionHandler(final int nWidth, final int nHeight, final boolean initlocal, final boolean initremote, final boolean acceptlocal,
67 final boolean acceptremote) {
68 super(TelnetOption.WINDOW_SIZE, initlocal, initremote, acceptlocal, acceptremote);
69
70 width = nWidth;
71 height = nHeight;
72 }
73
74 /**
75 * Implements the abstract method of TelnetOptionHandler. This will send the client Height and Width to the server.
76 *
77 * @return array to send to remote system
78 */
79 @Override
80 public int[] startSubnegotiationLocal() {
81 final int nCompoundWindowSize = width * 0x10000 + height;
82 int nResponseSize = 5;
83 int nIndex;
84 int nShift;
85 int nTurnedOnBits;
86
87 if (width % 0x100 == 0xFF) {
88 nResponseSize += 1;
89 }
90
91 if (width / 0x100 == 0xFF) {
92 nResponseSize += 1;
93 }
94
95 if (height % 0x100 == 0xFF) {
96 nResponseSize += 1;
97 }
98
99 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 }