001 /*
002 * Copyright 2001-2005 The Apache Software Foundation
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016 package org.apache.commons.net.tftp;
017
018 import java.net.DatagramPacket;
019 import java.net.InetAddress;
020
021 /***
022 * A final class derived from TFTPPacket definiing the TFTP Data
023 * packet type.
024 * <p>
025 * Details regarding the TFTP protocol and the format of TFTP packets can
026 * be found in RFC 783. But the point of these classes is to keep you
027 * from having to worry about the internals. Additionally, only very
028 * few people should have to care about any of the TFTPPacket classes
029 * or derived classes. Almost all users should only be concerned with the
030 * {@link org.apache.commons.net.tftp.TFTPClient} class
031 * {@link org.apache.commons.net.tftp.TFTPClient#receiveFile receiveFile()}
032 * and
033 * {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()}
034 * methods.
035 * <p>
036 * <p>
037 * @author Daniel F. Savarese
038 * @see TFTPPacket
039 * @see TFTPPacketException
040 * @see TFTP
041 ***/
042
043 public final class TFTPDataPacket extends TFTPPacket
044 {
045 /*** The maximum number of bytes in a TFTP data packet (512) ***/
046 public static final int MAX_DATA_LENGTH = 512;
047
048 /*** The minimum number of bytes in a TFTP data packet (0) ***/
049 public static final int MIN_DATA_LENGTH = 0;
050
051 /*** The block number of the packet. ***/
052 int _blockNumber;
053
054 /*** The length of the data. ***/
055 int _length;
056
057 /*** The offset into the _data array at which the data begins. ***/
058 int _offset;
059
060 /*** The data stored in the packet. ***/
061 byte[] _data;
062
063 /***
064 * Creates a data packet to be sent to a host at a given port
065 * with a given block number. The actual data to be sent is passed as
066 * an array, an offset, and a length. The offset is the offset into
067 * the byte array where the data starts. The length is the length of
068 * the data. If the length is greater than MAX_DATA_LENGTH, it is
069 * truncated.
070 * <p>
071 * @param destination The host to which the packet is going to be sent.
072 * @param port The port to which the packet is going to be sent.
073 * @param blockNumber The block number of the data.
074 * @param data The byte array containing the data.
075 * @param offset The offset into the array where the data starts.
076 * @param length The length of the data.
077 ***/
078 public TFTPDataPacket(InetAddress destination, int port, int blockNumber,
079 byte[] data, int offset, int length)
080 {
081 super(TFTPPacket.DATA, destination, port);
082
083 _blockNumber = blockNumber;
084 _data = data;
085 _offset = offset;
086
087 if (length > MAX_DATA_LENGTH)
088 _length = MAX_DATA_LENGTH;
089 else
090 _length = length;
091 }
092
093 public TFTPDataPacket(InetAddress destination, int port, int blockNumber,
094 byte[] data)
095 {
096 this(destination, port, blockNumber, data, 0, data.length);
097 }
098
099
100 /***
101 * Creates a data packet based from a received
102 * datagram. Assumes the datagram is at least length 4, else an
103 * ArrayIndexOutOfBoundsException may be thrown.
104 * <p>
105 * @param datagram The datagram containing the received data.
106 * @throws TFTPPacketException If the datagram isn't a valid TFTP
107 * data packet.
108 ***/
109 TFTPDataPacket(DatagramPacket datagram) throws TFTPPacketException
110 {
111 super(TFTPPacket.DATA, datagram.getAddress(), datagram.getPort());
112
113 _data = datagram.getData();
114 _offset = 4;
115
116 if (getType() != _data[1])
117 throw new TFTPPacketException("TFTP operator code does not match type.");
118
119 _blockNumber = (((_data[2] & 0xff) << 8) | (_data[3] & 0xff));
120
121 _length = datagram.getLength() - 4;
122
123 if (_length > MAX_DATA_LENGTH)
124 _length = MAX_DATA_LENGTH;
125 }
126
127 /***
128 * This is a method only available within the package for
129 * implementing efficient datagram transport by elminating buffering.
130 * It takes a datagram as an argument, and a byte buffer in which
131 * to store the raw datagram data. Inside the method, the data
132 * is set as the datagram's data and the datagram returned.
133 * <p>
134 * @param datagram The datagram to create.
135 * @param data The buffer to store the packet and to use in the datagram.
136 * @return The datagram argument.
137 ***/
138 DatagramPacket _newDatagram(DatagramPacket datagram, byte[] data)
139 {
140 data[0] = 0;
141 data[1] = (byte)_type;
142 data[2] = (byte)((_blockNumber & 0xffff) >> 8);
143 data[3] = (byte)(_blockNumber & 0xff);
144
145 // Doublecheck we're not the same
146 if (data != _data)
147 System.arraycopy(_data, _offset, data, 4, _length);
148
149 datagram.setAddress(_address);
150 datagram.setPort(_port);
151 datagram.setData(data);
152 datagram.setLength(_length + 4);
153
154 return datagram;
155 }
156
157 /***
158 * Creates a UDP datagram containing all the TFTP
159 * data packet data in the proper format.
160 * This is a method exposed to the programmer in case he
161 * wants to implement his own TFTP client instead of using
162 * the {@link org.apache.commons.net.tftp.TFTPClient}
163 * class.
164 * Under normal circumstances, you should not have a need to call this
165 * method.
166 * <p>
167 * @return A UDP datagram containing the TFTP data packet.
168 ***/
169 public DatagramPacket newDatagram()
170 {
171 byte[] data;
172
173 data = new byte[_length + 4];
174 data[0] = 0;
175 data[1] = (byte)_type;
176 data[2] = (byte)((_blockNumber & 0xffff) >> 8);
177 data[3] = (byte)(_blockNumber & 0xff);
178
179 System.arraycopy(_data, _offset, data, 4, _length);
180
181 return new DatagramPacket(data, _length + 4, _address, _port);
182 }
183
184 /***
185 * Returns the block number of the data packet.
186 * <p>
187 * @return The block number of the data packet.
188 ***/
189 public int getBlockNumber()
190 {
191 return _blockNumber;
192 }
193
194 /*** Sets the block number of the data packet. ***/
195 public void setBlockNumber(int blockNumber)
196 {
197 _blockNumber = blockNumber;
198 }
199
200 /***
201 * Sets the data for the data packet.
202 * <p>
203 * @param data The byte array containing the data.
204 * @param offset The offset into the array where the data starts.
205 * @param length The length of the data.
206 ***/
207 public void setData(byte[] data, int offset, int length)
208 {
209 _data = data;
210 _offset = offset;
211 _length = length;
212
213 if (length > MAX_DATA_LENGTH)
214 _length = MAX_DATA_LENGTH;
215 else
216 _length = length;
217 }
218
219 /***
220 * Returns the length of the data part of the data packet.
221 * <p>
222 * @return The length of the data part of the data packet.
223 ***/
224 public int getDataLength()
225 {
226 return _length;
227 }
228
229 /***
230 * Returns the offset into the byte array where the packet data actually
231 * starts.
232 * <p>
233 * @return The offset into the byte array where the packet data actually
234 * starts.
235 ***/
236 public int getDataOffset()
237 {
238 return _offset;
239 }
240
241 /***
242 * Returns the byte array containing the packet data.
243 * <p>
244 * @return The byte array containing the packet data.
245 ***/
246 public byte[] getData()
247 {
248 return _data;
249 }
250 }