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.tftp;
19
20 import java.net.DatagramPacket;
21 import java.net.InetAddress;
22
23 /***
24 * A final class derived from TFTPPacket definiing the TFTP Data
25 * packet type.
26 * <p>
27 * Details regarding the TFTP protocol and the format of TFTP packets can
28 * be found in RFC 783. But the point of these classes is to keep you
29 * from having to worry about the internals. Additionally, only very
30 * few people should have to care about any of the TFTPPacket classes
31 * or derived classes. Almost all users should only be concerned with the
32 * {@link org.apache.commons.net.tftp.TFTPClient} class
33 * {@link org.apache.commons.net.tftp.TFTPClient#receiveFile receiveFile()}
34 * and
35 * {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()}
36 * methods.
37 * <p>
38 * <p>
39 * @author Daniel F. Savarese
40 * @see TFTPPacket
41 * @see TFTPPacketException
42 * @see TFTP
43 ***/
44
45 public final class TFTPDataPacket extends TFTPPacket
46 {
47 /*** The maximum number of bytes in a TFTP data packet (512) ***/
48 public static final int MAX_DATA_LENGTH = 512;
49
50 /*** The minimum number of bytes in a TFTP data packet (0) ***/
51 public static final int MIN_DATA_LENGTH = 0;
52
53 /*** The block number of the packet. ***/
54 int _blockNumber;
55
56 /*** The length of the data. ***/
57 int _length;
58
59 /*** The offset into the _data array at which the data begins. ***/
60 int _offset;
61
62 /*** The data stored in the packet. ***/
63 byte[] _data;
64
65 /***
66 * Creates a data packet to be sent to a host at a given port
67 * with a given block number. The actual data to be sent is passed as
68 * an array, an offset, and a length. The offset is the offset into
69 * the byte array where the data starts. The length is the length of
70 * the data. If the length is greater than MAX_DATA_LENGTH, it is
71 * truncated.
72 * <p>
73 * @param destination The host to which the packet is going to be sent.
74 * @param port The port to which the packet is going to be sent.
75 * @param blockNumber The block number of the data.
76 * @param data The byte array containing the data.
77 * @param offset The offset into the array where the data starts.
78 * @param length The length of the data.
79 ***/
80 public TFTPDataPacket(InetAddress destination, int port, int blockNumber,
81 byte[] data, int offset, int length)
82 {
83 super(TFTPPacket.DATA, destination, port);
84
85 _blockNumber = blockNumber;
86 _data = data;
87 _offset = offset;
88
89 if (length > MAX_DATA_LENGTH)
90 _length = MAX_DATA_LENGTH;
91 else
92 _length = length;
93 }
94
95 public TFTPDataPacket(InetAddress destination, int port, int blockNumber,
96 byte[] data)
97 {
98 this(destination, port, blockNumber, data, 0, data.length);
99 }
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 _blockNumber = (((_data[2] & 0xff) << 8) | (_data[3] & 0xff));
122
123 _length = datagram.getLength() - 4;
124
125 if (_length > MAX_DATA_LENGTH)
126 _length = MAX_DATA_LENGTH;
127 }
128
129 /***
130 * This is a method only available within the package for
131 * implementing efficient datagram transport by elminating buffering.
132 * It takes a datagram as an argument, and a byte buffer in which
133 * to store the raw datagram data. Inside the method, the data
134 * is set as the datagram's data and the datagram returned.
135 * <p>
136 * @param datagram The datagram to create.
137 * @param data The buffer to store the packet and to use in the datagram.
138 * @return The datagram argument.
139 ***/
140 @Override
141 DatagramPacket _newDatagram(DatagramPacket datagram, byte[] data)
142 {
143 data[0] = 0;
144 data[1] = (byte)_type;
145 data[2] = (byte)((_blockNumber & 0xffff) >> 8);
146 data[3] = (byte)(_blockNumber & 0xff);
147
148 // Doublecheck we're not the same
149 if (data != _data)
150 System.arraycopy(_data, _offset, data, 4, _length);
151
152 datagram.setAddress(_address);
153 datagram.setPort(_port);
154 datagram.setData(data);
155 datagram.setLength(_length + 4);
156
157 return datagram;
158 }
159
160 /***
161 * Creates a UDP datagram containing all the TFTP
162 * data packet data in the proper format.
163 * This is a method exposed to the programmer in case he
164 * wants to implement his own TFTP client instead of using
165 * the {@link org.apache.commons.net.tftp.TFTPClient}
166 * class.
167 * Under normal circumstances, you should not have a need to call this
168 * method.
169 * <p>
170 * @return A UDP datagram containing the TFTP data packet.
171 ***/
172 @Override
173 public DatagramPacket newDatagram()
174 {
175 byte[] data;
176
177 data = new byte[_length + 4];
178 data[0] = 0;
179 data[1] = (byte)_type;
180 data[2] = (byte)((_blockNumber & 0xffff) >> 8);
181 data[3] = (byte)(_blockNumber & 0xff);
182
183 System.arraycopy(_data, _offset, data, 4, _length);
184
185 return new DatagramPacket(data, _length + 4, _address, _port);
186 }
187
188 /***
189 * Returns the block number of the data packet.
190 * <p>
191 * @return The block number of the data packet.
192 ***/
193 public int getBlockNumber()
194 {
195 return _blockNumber;
196 }
197
198 /*** Sets the block number of the data packet. ***/
199 public void setBlockNumber(int blockNumber)
200 {
201 _blockNumber = blockNumber;
202 }
203
204 /***
205 * Sets the data for the data packet.
206 * <p>
207 * @param data The byte array containing the data.
208 * @param offset The offset into the array where the data starts.
209 * @param length The length of the data.
210 ***/
211 public void setData(byte[] data, int offset, int length)
212 {
213 _data = data;
214 _offset = offset;
215 _length = length;
216
217 if (length > MAX_DATA_LENGTH)
218 _length = MAX_DATA_LENGTH;
219 else
220 _length = length;
221 }
222
223 /***
224 * Returns the length of the data part of the data packet.
225 * <p>
226 * @return The length of the data part of the data packet.
227 ***/
228 public int getDataLength()
229 {
230 return _length;
231 }
232
233 /***
234 * Returns the offset into the byte array where the packet data actually
235 * starts.
236 * <p>
237 * @return The offset into the byte array where the packet data actually
238 * starts.
239 ***/
240 public int getDataOffset()
241 {
242 return _offset;
243 }
244
245 /***
246 * Returns the byte array containing the packet data.
247 * <p>
248 * @return The byte array containing the packet data.
249 ***/
250 public byte[] getData()
251 {
252 return _data;
253 }
254 }