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 public TFTPDataPacket(InetAddress destination, int port, int blockNumber,
095 byte[] data)
096 {
097 this(destination, port, blockNumber, data, 0, data.length);
098 }
099
100
101 /***
102 * Creates a data packet based from a received
103 * datagram. Assumes the datagram is at least length 4, else an
104 * ArrayIndexOutOfBoundsException may be thrown.
105 * <p>
106 * @param datagram The datagram containing the received data.
107 * @throws TFTPPacketException If the datagram isn't a valid TFTP
108 * data packet.
109 ***/
110 TFTPDataPacket(DatagramPacket datagram) throws TFTPPacketException
111 {
112 super(TFTPPacket.DATA, datagram.getAddress(), datagram.getPort());
113
114 _data = datagram.getData();
115 _offset = 4;
116
117 if (getType() != _data[1])
118 throw new TFTPPacketException("TFTP operator code does not match type.");
119
120 _blockNumber = (((_data[2] & 0xff) << 8) | (_data[3] & 0xff));
121
122 _length = datagram.getLength() - 4;
123
124 if (_length > MAX_DATA_LENGTH)
125 _length = MAX_DATA_LENGTH;
126 }
127
128 /***
129 * This is a method only available within the package for
130 * implementing efficient datagram transport by elminating buffering.
131 * It takes a datagram as an argument, and a byte buffer in which
132 * to store the raw datagram data. Inside the method, the data
133 * is set as the datagram's data and the datagram returned.
134 * <p>
135 * @param datagram The datagram to create.
136 * @param data The buffer to store the packet and to use in the datagram.
137 * @return The datagram argument.
138 ***/
139 @Override
140 DatagramPacket _newDatagram(DatagramPacket datagram, byte[] data)
141 {
142 data[0] = 0;
143 data[1] = (byte)_type;
144 data[2] = (byte)((_blockNumber & 0xffff) >> 8);
145 data[3] = (byte)(_blockNumber & 0xff);
146
147 // Doublecheck we're not the same
148 if (data != _data)
149 System.arraycopy(_data, _offset, data, 4, _length);
150
151 datagram.setAddress(_address);
152 datagram.setPort(_port);
153 datagram.setData(data);
154 datagram.setLength(_length + 4);
155
156 return datagram;
157 }
158
159 /***
160 * Creates a UDP datagram containing all the TFTP
161 * data packet data in the proper format.
162 * This is a method exposed to the programmer in case he
163 * wants to implement his own TFTP client instead of using
164 * the {@link org.apache.commons.net.tftp.TFTPClient}
165 * class.
166 * Under normal circumstances, you should not have a need to call this
167 * method.
168 * <p>
169 * @return A UDP datagram containing the TFTP data packet.
170 ***/
171 @Override
172 public DatagramPacket newDatagram()
173 {
174 byte[] data;
175
176 data = new byte[_length + 4];
177 data[0] = 0;
178 data[1] = (byte)_type;
179 data[2] = (byte)((_blockNumber & 0xffff) >> 8);
180 data[3] = (byte)(_blockNumber & 0xff);
181
182 System.arraycopy(_data, _offset, data, 4, _length);
183
184 return new DatagramPacket(data, _length + 4, _address, _port);
185 }
186
187 /***
188 * Returns the block number of the data packet.
189 * <p>
190 * @return The block number of the data packet.
191 ***/
192 public int getBlockNumber()
193 {
194 return _blockNumber;
195 }
196
197 /*** Sets the block number of the data packet. ***/
198 public void setBlockNumber(int blockNumber)
199 {
200 _blockNumber = blockNumber;
201 }
202
203 /***
204 * Sets the data for the data packet.
205 * <p>
206 * @param data The byte array containing the data.
207 * @param offset The offset into the array where the data starts.
208 * @param length The length of the data.
209 ***/
210 public void setData(byte[] data, int offset, int length)
211 {
212 _data = data;
213 _offset = offset;
214 _length = length;
215
216 if (length > MAX_DATA_LENGTH)
217 _length = MAX_DATA_LENGTH;
218 else
219 _length = length;
220 }
221
222 /***
223 * Returns the length of the data part of the data packet.
224 * <p>
225 * @return The length of the data part of the data packet.
226 ***/
227 public int getDataLength()
228 {
229 return _length;
230 }
231
232 /***
233 * Returns the offset into the byte array where the packet data actually
234 * starts.
235 * <p>
236 * @return The offset into the byte array where the packet data actually
237 * starts.
238 ***/
239 public int getDataOffset()
240 {
241 return _offset;
242 }
243
244 /***
245 * Returns the byte array containing the packet data.
246 * <p>
247 * @return The byte array containing the packet data.
248 ***/
249 public byte[] getData()
250 {
251 return _data;
252 }
253 }