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
018package org.apache.commons.net.tftp;
019
020import java.net.DatagramPacket;
021import java.net.InetAddress;
022
023/**
024 * An abstract class derived from TFTPPacket definiing a TFTP Request
025 * packet type.  It is subclassed by the
026 * {@link org.apache.commons.net.tftp.TFTPReadRequestPacket}
027 *   and
028 * {@link org.apache.commons.net.tftp.TFTPWriteRequestPacket}
029 *  classes.
030 * <p>
031 * Details regarding the TFTP protocol and the format of TFTP packets can
032 * be found in RFC 783.  But the point of these classes is to keep you
033 * from having to worry about the internals.  Additionally, only very
034 * few people should have to care about any of the TFTPPacket classes
035 * or derived classes.  Almost all users should only be concerned with the
036 * {@link org.apache.commons.net.tftp.TFTPClient} class
037 * {@link org.apache.commons.net.tftp.TFTPClient#receiveFile receiveFile()}
038 * and
039 * {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()}
040 * methods.
041 *
042 *
043 * @see TFTPPacket
044 * @see TFTPReadRequestPacket
045 * @see TFTPWriteRequestPacket
046 * @see TFTPPacketException
047 * @see TFTP
048 */
049
050public abstract class TFTPRequestPacket extends TFTPPacket
051{
052    /**
053     * An array containing the string names of the transfer modes and indexed
054     * by the transfer mode constants.
055     */
056    static final String[] modeStrings = { "netascii", "octet" };
057
058    /**
059     * A null terminated byte array representation of the ascii names of the
060     * transfer mode constants.  This is convenient for creating the TFTP
061     * request packets.
062     */
063    private static final byte[] modeBytes[] = {
064                                           { (byte)'n', (byte)'e', (byte)'t', (byte)'a', (byte)'s', (byte)'c',
065                                             (byte)'i', (byte)'i', 0 },
066                                           { (byte)'o', (byte)'c', (byte)'t', (byte)'e', (byte)'t', 0 }
067                                       };
068
069    /** The transfer mode of the request. */
070    private final int mode;
071
072    /** The file name of the request. */
073    private final String fileName;
074
075    /**
076     * Creates a request packet of a given type to be sent to a host at a
077     * given port with a file name and transfer mode request.
078     *
079     * @param destination  The host to which the packet is going to be sent.
080     * @param port  The port to which the packet is going to be sent.
081     * @param type The type of the request (either TFTPPacket.READ_REQUEST or
082     *             TFTPPacket.WRITE_REQUEST).
083     * @param fileName The requested file name.
084     * @param mode The requested transfer mode.  This should be on of the TFTP
085     *        class MODE constants (e.g., TFTP.NETASCII_MODE).
086     */
087    TFTPRequestPacket(final InetAddress destination, final int port,
088                      final int type, final String fileName, final int mode)
089    {
090        super(type, destination, port);
091
092        this.fileName = fileName;
093        this.mode = mode;
094    }
095
096    /**
097     * Creates a request packet of a given type based on a received
098     * datagram.  Assumes the datagram is at least length 4, else an
099     * ArrayIndexOutOfBoundsException may be thrown.
100     *
101     * @param type The type of the request (either TFTPPacket.READ_REQUEST or
102     *             TFTPPacket.WRITE_REQUEST).
103     * @param datagram  The datagram containing the received request.
104     * @throws TFTPPacketException  If the datagram isn't a valid TFTP
105     *         request packet of the appropriate type.
106     */
107    TFTPRequestPacket(final int type, final DatagramPacket datagram)
108    throws TFTPPacketException
109    {
110        super(type, datagram.getAddress(), datagram.getPort());
111
112        final byte[] data = datagram.getData();
113
114        if (getType() != data[1]) {
115            throw new TFTPPacketException("TFTP operator code does not match type.");
116        }
117
118        final StringBuilder buffer = new StringBuilder();
119
120        int index = 2;
121        int length = datagram.getLength();
122
123        while (index < length && data[index] != 0)
124        {
125            buffer.append((char)data[index]);
126            ++index;
127        }
128
129        this.fileName = buffer.toString();
130
131        if (index >= length) {
132            throw new TFTPPacketException("Bad file name and mode format.");
133        }
134
135        buffer.setLength(0);
136        ++index; // need to advance beyond the end of string marker
137        while (index < length && data[index] != 0)
138        {
139            buffer.append((char)data[index]);
140            ++index;
141        }
142
143        final String modeString = buffer.toString().toLowerCase(java.util.Locale.ENGLISH);
144        length = modeStrings.length;
145
146        int mode = 0;
147        for (index = 0; index < length; index++)
148        {
149            if (modeString.equals(modeStrings[index]))
150            {
151                mode = index;
152                break;
153            }
154        }
155
156        this.mode = mode;
157
158        if (index >= length)
159        {
160            throw new TFTPPacketException("Unrecognized TFTP transfer mode: " + modeString);
161            // May just want to default to binary mode instead of throwing
162            // exception.
163            //_mode = TFTP.OCTET_MODE;
164        }
165    }
166
167
168    /**
169     * This is a method only available within the package for
170     * implementing efficient datagram transport by elminating buffering.
171     * It takes a datagram as an argument, and a byte buffer in which
172     * to store the raw datagram data.  Inside the method, the data
173     * is set as the datagram's data and the datagram returned.
174     *
175     * @param datagram  The datagram to create.
176     * @param data The buffer to store the packet and to use in the datagram.
177     * @return The datagram argument.
178     */
179    @Override
180    final DatagramPacket newDatagram(final DatagramPacket datagram, final byte[] data)
181    {
182        final int fileLength;
183        final int modeLength;
184
185        fileLength = fileName.length();
186        modeLength = modeBytes[mode].length;
187
188        data[0] = 0;
189        data[1] = (byte)type;
190        System.arraycopy(fileName.getBytes(), 0, data, 2, fileLength);
191        data[fileLength + 2] = 0;
192        System.arraycopy(modeBytes[mode], 0, data, fileLength + 3,
193                         modeLength);
194
195        datagram.setAddress(address);
196        datagram.setPort(port);
197        datagram.setData(data);
198        datagram.setLength(fileLength + modeLength + 3);
199
200        return datagram;
201    }
202
203    /**
204     * Creates a UDP datagram containing all the TFTP
205     * request packet data in the proper format.
206     * This is a method exposed to the programmer in case he
207     * wants to implement his own TFTP client instead of using
208     * the {@link org.apache.commons.net.tftp.TFTPClient}
209     * class.  Under normal circumstances, you should not have a need to call
210     * this method.
211     *
212     * @return A UDP datagram containing the TFTP request packet.
213     */
214    @Override
215    public final DatagramPacket newDatagram()
216    {
217        final int fileLength;
218        final int modeLength;
219        final byte[] data;
220
221        fileLength = fileName.length();
222        modeLength = modeBytes[mode].length;
223
224        data = new byte[fileLength + modeLength + 4];
225        data[0] = 0;
226        data[1] = (byte)type;
227        System.arraycopy(fileName.getBytes(), 0, data, 2, fileLength);
228        data[fileLength + 2] = 0;
229        System.arraycopy(modeBytes[mode], 0, data, fileLength + 3,
230                         modeLength);
231
232        return new DatagramPacket(data, data.length, address, port);
233    }
234
235    /**
236     * Returns the transfer mode of the request.
237     *
238     * @return The transfer mode of the request.
239     */
240    public final int getMode()
241    {
242        return mode;
243    }
244
245    /**
246     * Returns the requested file name.
247     *
248     * @return The requested file name.
249     */
250    public final String getFilename()
251    {
252        return fileName;
253    }
254}