Source code

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 *      https://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
018package org.apache.commons.net.tftp;
019
020import java.net.DatagramPacket;
021import java.net.InetAddress;
022
023/**
024 * A final class derived from TFTPPacket defining the TFTP Data packet type.
025 * <p>
026 * 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
027 * 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
028 * should only be concerned with the {@link org.apache.commons.net.tftp.TFTPClient} class {@link org.apache.commons.net.tftp.TFTPClient#receiveFile
029 * receiveFile()} and {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()} methods.
030 * </p>
031 *
032 * @see TFTPPacket
033 * @see TFTPPacketException
034 * @see TFTP
035 */
036
037public final class TFTPDataPacket extends TFTPPacket {
038    /** The maximum number of bytes in a TFTP data packet (512) */
039    public static final int MAX_DATA_LENGTH = 512;
040
041    /** The minimum number of bytes in a TFTP data packet (0) */
042    public static final int MIN_DATA_LENGTH = 0;
043
044    /** The block number of the packet. */
045    int blockNumber;
046
047    /** The length of the data. */
048    private int length;
049
050    /** The offset into the _data array at which the data begins. */
051    private int offset;
052
053    /** The data stored in the packet. */
054    private byte[] data;
055
056    /**
057     * Creates a data packet based from a received datagram. Assumes the datagram is at least length 4, else an ArrayIndexOutOfBoundsException may be thrown.
058     *
059     * @param datagram The datagram containing the received data.
060     * @throws TFTPPacketException If the datagram isn't a valid TFTP data packet.
061     */
062    TFTPDataPacket(final DatagramPacket datagram) throws TFTPPacketException {
063        super(DATA, datagram.getAddress(), datagram.getPort());
064
065        this.data = datagram.getData();
066        this.offset = 4;
067
068        if (getType() != this.data[1]) {
069            throw new TFTPPacketException("TFTP operator code does not match type.");
070        }
071
072        this.blockNumber = (this.data[2] & 0xff) << 8 | this.data[3] & 0xff;
073
074        this.length = datagram.getLength() - 4;
075    }
076
077    /**
078     * 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
079     * length. The offset is the offset into the byte array where the data starts. The length is the length of the data.
080     *
081     * @param destination The host to which the packet is going to be sent.
082     * @param port        The port to which the packet is going to be sent.
083     * @param blockNumber The block number of the data.
084     * @param data        The byte array containing the data.
085     */
086    public TFTPDataPacket(final InetAddress destination, final int port, final int blockNumber, final byte[] data) {
087        this(destination, port, blockNumber, data, 0, data.length);
088    }
089
090    /**
091     * 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
092     * length. The offset is the offset into the byte array where the data starts. The length is the length of the data.
093     *
094     * @param destination The host to which the packet is going to be sent.
095     * @param port        The port to which the packet is going to be sent.
096     * @param blockNumber The block number of the data.
097     * @param data        The byte array containing the data.
098     * @param offset      The offset into the array where the data starts.
099     * @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}