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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    *      http://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   * An abstract class derived from TFTPPacket definiing a TFTP Request
25   * packet type.  It is subclassed by the
26   * {@link org.apache.commons.net.tftp.TFTPReadRequestPacket}
27   *   and
28   * {@link org.apache.commons.net.tftp.TFTPWriteRequestPacket}
29   *  classes.
30   * <p>
31   * Details regarding the TFTP protocol and the format of TFTP packets can
32   * be found in RFC 783.  But the point of these classes is to keep you
33   * from having to worry about the internals.  Additionally, only very
34   * few people should have to care about any of the TFTPPacket classes
35   * or derived classes.  Almost all users should only be concerned with the
36   * {@link org.apache.commons.net.tftp.TFTPClient} class
37   * {@link org.apache.commons.net.tftp.TFTPClient#receiveFile receiveFile()}
38   * and
39   * {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()}
40   * methods.
41   * <p>
42   * <p>
43   * @see TFTPPacket
44   * @see TFTPReadRequestPacket
45   * @see TFTPWriteRequestPacket
46   * @see TFTPPacketException
47   * @see TFTP
48   ***/
49  
50  public abstract class TFTPRequestPacket extends TFTPPacket
51  {
52      /***
53       * An array containing the string names of the transfer modes and indexed
54       * by the transfer mode constants.
55       ***/
56      static final String[] _modeStrings = { "netascii", "octet" };
57  
58      /***
59       * A null terminated byte array representation of the ascii names of the
60       * transfer mode constants.  This is convenient for creating the TFTP
61       * request packets.
62       ***/
63      private static final byte[] _modeBytes[] = {
64                                             { (byte)'n', (byte)'e', (byte)'t', (byte)'a', (byte)'s', (byte)'c',
65                                               (byte)'i', (byte)'i', 0 },
66                                             { (byte)'o', (byte)'c', (byte)'t', (byte)'e', (byte)'t', 0 }
67                                         };
68  
69      /*** The transfer mode of the request. ***/
70      private final int _mode;
71  
72      /*** The filename of the request. ***/
73      private final String _filename;
74  
75      /***
76       * Creates a request packet of a given type to be sent to a host at a
77       * given port with a filename and transfer mode request.
78       * <p>
79       * @param destination  The host to which the packet is going to be sent.
80       * @param port  The port to which the packet is going to be sent.
81       * @param type The type of the request (either TFTPPacket.READ_REQUEST or
82       *             TFTPPacket.WRITE_REQUEST).
83       * @param filename The requested filename.
84       * @param mode The requested transfer mode.  This should be on of the TFTP
85       *        class MODE constants (e.g., TFTP.NETASCII_MODE).
86       ***/
87      TFTPRequestPacket(InetAddress destination, int port,
88                        int type, String filename, int mode)
89      {
90          super(type, destination, port);
91  
92          _filename = filename;
93          _mode = mode;
94      }
95  
96      /***
97       * Creates a request packet of a given type based on a received
98       * datagram.  Assumes the datagram is at least length 4, else an
99       * ArrayIndexOutOfBoundsException may be thrown.
100      * <p>
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(int type, DatagramPacket datagram)
108     throws TFTPPacketException
109     {
110         super(type, datagram.getAddress(), datagram.getPort());
111 
112         byte[] data = datagram.getData();
113 
114         if (getType() != data[1]) {
115             throw new TFTPPacketException("TFTP operator code does not match type.");
116         }
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 
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         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         _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      * <p>
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(DatagramPacket datagram, byte[] data)
181     {
182         int fileLength, modeLength;
183 
184         fileLength = _filename.length();
185         modeLength = _modeBytes[_mode].length;
186 
187         data[0] = 0;
188         data[1] = (byte)_type;
189         System.arraycopy(_filename.getBytes(), 0, data, 2, fileLength);
190         data[fileLength + 2] = 0;
191         System.arraycopy(_modeBytes[_mode], 0, data, fileLength + 3,
192                          modeLength);
193 
194         datagram.setAddress(_address);
195         datagram.setPort(_port);
196         datagram.setData(data);
197         datagram.setLength(fileLength + modeLength + 3);
198 
199         return datagram;
200     }
201 
202     /***
203      * Creates a UDP datagram containing all the TFTP
204      * request packet data in the proper format.
205      * This is a method exposed to the programmer in case he
206      * wants to implement his own TFTP client instead of using
207      * the {@link org.apache.commons.net.tftp.TFTPClient}
208      * class.  Under normal circumstances, you should not have a need to call
209      * this method.
210      * <p>
211      * @return A UDP datagram containing the TFTP request packet.
212      ***/
213     @Override
214     public final DatagramPacket newDatagram()
215     {
216         int fileLength, modeLength;
217         byte[] data;
218 
219         fileLength = _filename.length();
220         modeLength = _modeBytes[_mode].length;
221 
222         data = new byte[fileLength + modeLength + 4];
223         data[0] = 0;
224         data[1] = (byte)_type;
225         System.arraycopy(_filename.getBytes(), 0, data, 2, fileLength);
226         data[fileLength + 2] = 0;
227         System.arraycopy(_modeBytes[_mode], 0, data, fileLength + 3,
228                          modeLength);
229 
230         return new DatagramPacket(data, data.length, _address, _port);
231     }
232 
233     /***
234      * Returns the transfer mode of the request.
235      * <p>
236      * @return The transfer mode of the request.
237      ***/
238     public final int getMode()
239     {
240         return _mode;
241     }
242 
243     /***
244      * Returns the requested filename.
245      * <p>
246      * @return The requested filename.
247      ***/
248     public final String getFilename()
249     {
250         return _filename;
251     }
252 }