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        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        int _mode;
072    
073        /*** The filename of the request. ***/
074        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;
114            int index, length;
115            String mode;
116            StringBuffer buffer;
117    
118            data = datagram.getData();
119    
120            if (getType() != data[1])
121                throw new TFTPPacketException("TFTP operator code does not match type.");
122    
123            buffer = new StringBuffer();
124    
125            index = 2;
126            length = datagram.getLength();
127    
128            while (index < length && data[index] != 0)
129            {
130                buffer.append((char)data[index]);
131                ++index;
132            }
133    
134            _filename = buffer.toString();
135    
136            if (index >= length)
137                throw new TFTPPacketException("Bad filename and mode format.");
138    
139            buffer.setLength(0);
140            ++index; // need to advance beyond the end of string marker
141            while (index < length && data[index] != 0)
142            {
143                buffer.append((char)data[index]);
144                ++index;
145            }
146    
147            mode = buffer.toString().toLowerCase(java.util.Locale.ENGLISH);
148            length = _modeStrings.length;
149    
150            for (index = 0; index < length; index++)
151            {
152                if (mode.equals(_modeStrings[index]))
153                {
154                    _mode = index;
155                    break;
156                }
157            }
158    
159            if (index >= length)
160            {
161                throw new TFTPPacketException("Unrecognized TFTP transfer mode: " + mode);
162                // May just want to default to binary mode instead of throwing
163                // exception.
164                //_mode = TFTP.OCTET_MODE;
165            }
166        }
167    
168    
169        /***
170         * This is a method only available within the package for
171         * implementing efficient datagram transport by elminating buffering.
172         * It takes a datagram as an argument, and a byte buffer in which
173         * to store the raw datagram data.  Inside the method, the data
174         * is set as the datagram's data and the datagram returned.
175         * <p>
176         * @param datagram  The datagram to create.
177         * @param data The buffer to store the packet and to use in the datagram.
178         * @return The datagram argument.
179         ***/
180        @Override
181        final DatagramPacket _newDatagram(DatagramPacket datagram, byte[] data)
182        {
183            int fileLength, 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         * <p>
212         * @return A UDP datagram containing the TFTP request packet.
213         ***/
214        @Override
215        public final DatagramPacket newDatagram()
216        {
217            int fileLength, modeLength;
218            byte[] data;
219    
220            fileLength = _filename.length();
221            modeLength = _modeBytes[_mode].length;
222    
223            data = new byte[fileLength + modeLength + 4];
224            data[0] = 0;
225            data[1] = (byte)_type;
226            System.arraycopy(_filename.getBytes(), 0, data, 2, fileLength);
227            data[fileLength + 2] = 0;
228            System.arraycopy(_modeBytes[_mode], 0, data, fileLength + 3,
229                             modeLength);
230    
231            return new DatagramPacket(data, data.length, _address, _port);
232        }
233    
234        /***
235         * Returns the transfer mode of the request.
236         * <p>
237         * @return The transfer mode of the request.
238         ***/
239        public final int getMode()
240        {
241            return _mode;
242        }
243    
244        /***
245         * Returns the requested filename.
246         * <p>
247         * @return The requested filename.
248         ***/
249        public final String getFilename()
250        {
251            return _filename;
252        }
253    }