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
018 package org.apache.commons.net.tftp;
019
020 import java.net.DatagramPacket;
021 import java.net.InetAddress;
022
023 /***
024 * A final class derived from TFTPPacket definiing the TFTP Data
025 * packet type.
026 * <p>
027 * Details regarding the TFTP protocol and the format of TFTP packets can
028 * be found in RFC 783. But the point of these classes is to keep you
029 * from having to worry about the internals. Additionally, only very
030 * few people should have to care about any of the TFTPPacket classes
031 * or derived classes. Almost all users should only be concerned with the
032 * {@link org.apache.commons.net.tftp.TFTPClient} class
033 * {@link org.apache.commons.net.tftp.TFTPClient#receiveFile receiveFile()}
034 * and
035 * {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()}
036 * methods.
037 * <p>
038 * <p>
039 * @see TFTPPacket
040 * @see TFTPPacketException
041 * @see TFTP
042 ***/
043
044 public final class TFTPDataPacket extends TFTPPacket
045 {
046 /*** The maximum number of bytes in a TFTP data packet (512) ***/
047 public static final int MAX_DATA_LENGTH = 512;
048
049 /*** The minimum number of bytes in a TFTP data packet (0) ***/
050 public static final int MIN_DATA_LENGTH = 0;
051
052 /*** The block number of the packet. ***/
053 int _blockNumber;
054
055 /*** The length of the data. ***/
056 int _length;
057
058 /*** The offset into the _data array at which the data begins. ***/
059 int _offset;
060
061 /*** The data stored in the packet. ***/
062 byte[] _data;
063
064 /***
065 * Creates a data packet to be sent to a host at a given port
066 * with a given block number. The actual data to be sent is passed as
067 * an array, an offset, and a length. The offset is the offset into
068 * the byte array where the data starts. The length is the length of
069 * the data. If the length is greater than MAX_DATA_LENGTH, it is
070 * truncated.
071 * <p>
072 * @param destination The host to which the packet is going to be sent.
073 * @param port The port to which the packet is going to be sent.
074 * @param blockNumber The block number of the data.
075 * @param data The byte array containing the data.
076 * @param offset The offset into the array where the data starts.
077 * @param length The length of the data.
078 ***/
079 public TFTPDataPacket(InetAddress destination, int port, int blockNumber,
080 byte[] data, int offset, int length)
081 {
082 super(TFTPPacket.DATA, destination, port);
083
084 _blockNumber = blockNumber;
085 _data = data;
086 _offset = offset;
087
088 if (length > MAX_DATA_LENGTH) {
089 _length = MAX_DATA_LENGTH;
090 } else {
091 _length = length;
092 }
093 }
094
095 public TFTPDataPacket(InetAddress destination, int port, int blockNumber,
096 byte[] data)
097 {
098 this(destination, port, blockNumber, data, 0, data.length);
099 }
100
101
102 /***
103 * Creates a data packet based from a received
104 * datagram. Assumes the datagram is at least length 4, else an
105 * ArrayIndexOutOfBoundsException may be thrown.
106 * <p>
107 * @param datagram The datagram containing the received data.
108 * @throws TFTPPacketException If the datagram isn't a valid TFTP
109 * data packet.
110 ***/
111 TFTPDataPacket(DatagramPacket datagram) throws TFTPPacketException
112 {
113 super(TFTPPacket.DATA, datagram.getAddress(), datagram.getPort());
114
115 _data = datagram.getData();
116 _offset = 4;
117
118 if (getType() != _data[1]) {
119 throw new TFTPPacketException("TFTP operator code does not match type.");
120 }
121
122 _blockNumber = (((_data[2] & 0xff) << 8) | (_data[3] & 0xff));
123
124 _length = datagram.getLength() - 4;
125
126 if (_length > MAX_DATA_LENGTH) {
127 _length = MAX_DATA_LENGTH;
128 }
129 }
130
131 /***
132 * This is a method only available within the package for
133 * implementing efficient datagram transport by elminating buffering.
134 * It takes a datagram as an argument, and a byte buffer in which
135 * to store the raw datagram data. Inside the method, the data
136 * is set as the datagram's data and the datagram returned.
137 * <p>
138 * @param datagram The datagram to create.
139 * @param data The buffer to store the packet and to use in the datagram.
140 * @return The datagram argument.
141 ***/
142 @Override
143 DatagramPacket _newDatagram(DatagramPacket datagram, byte[] data)
144 {
145 data[0] = 0;
146 data[1] = (byte)_type;
147 data[2] = (byte)((_blockNumber & 0xffff) >> 8);
148 data[3] = (byte)(_blockNumber & 0xff);
149
150 // Doublecheck we're not the same
151 if (data != _data) {
152 System.arraycopy(_data, _offset, data, 4, _length);
153 }
154
155 datagram.setAddress(_address);
156 datagram.setPort(_port);
157 datagram.setData(data);
158 datagram.setLength(_length + 4);
159
160 return datagram;
161 }
162
163 /***
164 * Creates a UDP datagram containing all the TFTP
165 * data packet data in the proper format.
166 * This is a method exposed to the programmer in case he
167 * wants to implement his own TFTP client instead of using
168 * the {@link org.apache.commons.net.tftp.TFTPClient}
169 * class.
170 * Under normal circumstances, you should not have a need to call this
171 * method.
172 * <p>
173 * @return A UDP datagram containing the TFTP data packet.
174 ***/
175 @Override
176 public DatagramPacket newDatagram()
177 {
178 byte[] data;
179
180 data = new byte[_length + 4];
181 data[0] = 0;
182 data[1] = (byte)_type;
183 data[2] = (byte)((_blockNumber & 0xffff) >> 8);
184 data[3] = (byte)(_blockNumber & 0xff);
185
186 System.arraycopy(_data, _offset, data, 4, _length);
187
188 return new DatagramPacket(data, _length + 4, _address, _port);
189 }
190
191 /***
192 * Returns the block number of the data packet.
193 * <p>
194 * @return The block number of the data packet.
195 ***/
196 public int getBlockNumber()
197 {
198 return _blockNumber;
199 }
200
201 /*** Sets the block number of the data packet. ***/
202 public void setBlockNumber(int blockNumber)
203 {
204 _blockNumber = blockNumber;
205 }
206
207 /***
208 * Sets the data for the data packet.
209 * <p>
210 * @param data The byte array containing the data.
211 * @param offset The offset into the array where the data starts.
212 * @param length The length of the data.
213 ***/
214 public void setData(byte[] data, int offset, int length)
215 {
216 _data = data;
217 _offset = offset;
218 _length = length;
219
220 if (length > MAX_DATA_LENGTH) {
221 _length = MAX_DATA_LENGTH;
222 } else {
223 _length = length;
224 }
225 }
226
227 /***
228 * Returns the length of the data part of the data packet.
229 * <p>
230 * @return The length of the data part of the data packet.
231 ***/
232 public int getDataLength()
233 {
234 return _length;
235 }
236
237 /***
238 * Returns the offset into the byte array where the packet data actually
239 * starts.
240 * <p>
241 * @return The offset into the byte array where the packet data actually
242 * starts.
243 ***/
244 public int getDataOffset()
245 {
246 return _offset;
247 }
248
249 /***
250 * Returns the byte array containing the packet data.
251 * <p>
252 * @return The byte array containing the packet data.
253 ***/
254 public byte[] getData()
255 {
256 return _data;
257 }
258 }