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 * https://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 defining the TFTP Data packet type.
25 * <p>
26 * Details regarding the TFTP protocol and the format of TFTP packets can be found in RFC 783. But the point of these classes is to keep you from having to
27 * worry about the internals. Additionally, only very few people should have to care about any of the TFTPPacket classes or derived classes. Almost all users
28 * should only be concerned with the {@link org.apache.commons.net.tftp.TFTPClient} class {@link org.apache.commons.net.tftp.TFTPClient#receiveFile
29 * receiveFile()} and {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()} methods.
30 * </p>
31 *
32 * @see TFTPPacket
33 * @see TFTPPacketException
34 * @see TFTP
35 */
36
37 public final class TFTPDataPacket extends TFTPPacket {
38 /** The maximum number of bytes in a TFTP data packet (512) */
39 public static final int MAX_DATA_LENGTH = 512;
40
41 /** The minimum number of bytes in a TFTP data packet (0) */
42 public static final int MIN_DATA_LENGTH = 0;
43
44 /** The block number of the packet. */
45 int blockNumber;
46
47 /** The length of the data. */
48 private int length;
49
50 /** The offset into the _data array at which the data begins. */
51 private int offset;
52
53 /** The data stored in the packet. */
54 private byte[] data;
55
56 /**
57 * Creates a data packet based from a received datagram. Assumes the datagram is at least length 4, else an ArrayIndexOutOfBoundsException may be thrown.
58 *
59 * @param datagram The datagram containing the received data.
60 * @throws TFTPPacketException If the datagram isn't a valid TFTP data packet.
61 */
62 TFTPDataPacket(final DatagramPacket datagram) throws TFTPPacketException {
63 super(DATA, datagram.getAddress(), datagram.getPort());
64
65 this.data = datagram.getData();
66 this.offset = 4;
67
68 if (getType() != this.data[1]) {
69 throw new TFTPPacketException("TFTP operator code does not match type.");
70 }
71
72 this.blockNumber = (this.data[2] & 0xff) << 8 | this.data[3] & 0xff;
73
74 this.length = datagram.getLength() - 4;
75 }
76
77 /**
78 * Creates a data packet to be sent to a host at a given port with a given block number. The actual data to be sent is passed as an array, an offset, and a
79 * length. The offset is the offset into the byte array where the data starts. The length is the length of the data.
80 *
81 * @param destination The host to which the packet is going to be sent.
82 * @param port The port to which the packet is going to be sent.
83 * @param blockNumber The block number of the data.
84 * @param data The byte array containing the data.
85 */
86 public TFTPDataPacket(final InetAddress destination, final int port, final int blockNumber, final byte[] data) {
87 this(destination, port, blockNumber, data, 0, data.length);
88 }
89
90 /**
91 * Creates a data packet to be sent to a host at a given port with a given block number. The actual data to be sent is passed as an array, an offset, and a
92 * length. The offset is the offset into the byte array where the data starts. The length is the length of the data.
93 *
94 * @param destination The host to which the packet is going to be sent.
95 * @param port The port to which the packet is going to be sent.
96 * @param blockNumber The block number of the data.
97 * @param data The byte array containing the data.
98 * @param offset The offset into the array where the data starts.
99 * @param length The length of the data.
100 */
101 public TFTPDataPacket(final InetAddress destination, final int port, final int blockNumber, final byte[] data, final int offset, final int length) {
102 super(DATA, destination, port);
103 this.blockNumber = blockNumber;
104 this.data = data;
105 this.offset = offset;
106 this.length = length;
107 }
108
109 /**
110 * Gets the block number of the data packet.
111 *
112 * @return The block number of the data packet.
113 */
114 public int getBlockNumber() {
115 return blockNumber;
116 }
117
118 /**
119 * Gets the byte array containing the packet data.
120 *
121 * @return The byte array containing the packet data.
122 */
123 public byte[] getData() {
124 return data;
125 }
126
127 /**
128 * Gets the length of the data part of the data packet.
129 *
130 * @return The length of the data part of the data packet.
131 */
132 public int getDataLength() {
133 return length;
134 }
135
136 /**
137 * Gets the offset into the byte array where the packet data actually starts.
138 *
139 * @return The offset into the byte array where the packet data actually starts.
140 */
141 public int getDataOffset() {
142 return offset;
143 }
144
145 /**
146 * Creates a UDP datagram containing all the TFTP data packet data in the proper format. This is a method exposed to the programmer in case he wants to
147 * implement his own TFTP client instead of using the {@link org.apache.commons.net.tftp.TFTPClient} class. Under normal circumstances, you should not have
148 * a need to call this method.
149 *
150 * @return A UDP datagram containing the TFTP data packet.
151 */
152 @Override
153 public DatagramPacket newDatagram() {
154 final byte[] data;
155
156 data = new byte[length + 4];
157 data[0] = 0;
158 data[1] = (byte) type;
159 data[2] = (byte) ((blockNumber & 0xffff) >> 8);
160 data[3] = (byte) (blockNumber & 0xff);
161
162 System.arraycopy(this.data, offset, data, 4, length);
163
164 return new DatagramPacket(data, length + 4, address, port);
165 }
166
167 /**
168 * This is a method only available within the package for implementing efficient datagram transport by eliminating buffering. It takes a datagram as an
169 * argument, and a byte buffer in which to store the raw datagram data. Inside the method, the data is set as the datagram's data and the datagram returned.
170 *
171 * @param datagram The datagram to create.
172 * @param data The buffer to store the packet and to use in the datagram.
173 * @return The datagram argument.
174 */
175 @Override
176 DatagramPacket newDatagram(final DatagramPacket datagram, final byte[] data) {
177 data[0] = 0;
178 data[1] = (byte) type;
179 data[2] = (byte) ((blockNumber & 0xffff) >> 8);
180 data[3] = (byte) (blockNumber & 0xff);
181
182 // Doublecheck we're not the same
183 if (data != this.data) {
184 System.arraycopy(this.data, offset, data, 4, length);
185 }
186
187 datagram.setAddress(address);
188 datagram.setPort(port);
189 datagram.setData(data);
190 datagram.setLength(length + 4);
191
192 return datagram;
193 }
194
195 /**
196 * Sets the block number of the data packet.
197 *
198 * @param blockNumber the number to set
199 */
200 public void setBlockNumber(final int blockNumber) {
201 this.blockNumber = blockNumber;
202 }
203
204 /**
205 * Sets the data for the data packet.
206 *
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(final byte[] data, final int offset, final int length) {
212 this.data = data;
213 this.offset = offset;
214 this.length = length;
215 }
216
217 /**
218 * For debugging
219 *
220 * @since 3.6
221 */
222 @Override
223 public String toString() {
224 return super.toString() + " DATA " + blockNumber + " " + length;
225 }
226 }