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