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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.io.IOException;
21  import java.io.InterruptedIOException;
22  import java.net.DatagramPacket;
23  import java.net.SocketException;
24  
25  import org.apache.commons.net.DatagramSocketClient;
26  
27  /***
28   * The TFTP class exposes a set of methods to allow you to deal with the TFTP
29   * protocol directly, in case you want to write your own TFTP client or
30   * server.  However, almost every user should only be concerend with
31   * the {@link org.apache.commons.net.DatagramSocketClient#open  open() },
32   * and {@link org.apache.commons.net.DatagramSocketClient#close  close() },
33   * methods. Additionally,the a
34   * {@link org.apache.commons.net.DatagramSocketClient#setDefaultTimeout setDefaultTimeout() }
35   *  method may be of importance for performance tuning.
36   * <p>
37   * Details regarding the TFTP protocol and the format of TFTP packets can
38   * be found in RFC 783.  But the point of these classes is to keep you
39   * from having to worry about the internals.
40   *
41   *
42   * @see org.apache.commons.net.DatagramSocketClient
43   * @see TFTPPacket
44   * @see TFTPPacketException
45   * @see TFTPClient
46   ***/
47  
48  public class TFTP extends DatagramSocketClient
49  {
50      /***
51       * The ascii transfer mode.  Its value is 0 and equivalent to NETASCII_MODE
52       ***/
53      public static final int ASCII_MODE = 0;
54  
55      /***
56       * The netascii transfer mode.  Its value is 0.
57       ***/
58      public static final int NETASCII_MODE = 0;
59  
60      /***
61       * The binary transfer mode.  Its value is 1 and equivalent to OCTET_MODE.
62       ***/
63      public static final int BINARY_MODE = 1;
64  
65      /***
66       * The image transfer mode.  Its value is 1 and equivalent to OCTET_MODE.
67       ***/
68      public static final int IMAGE_MODE = 1;
69  
70      /***
71       * The octet transfer mode.  Its value is 1.
72       ***/
73      public static final int OCTET_MODE = 1;
74  
75      /***
76       * The default number of milliseconds to wait to receive a datagram
77       * before timing out.  The default is 5000 milliseconds (5 seconds).
78       ***/
79      public static final int DEFAULT_TIMEOUT = 5000;
80  
81      /***
82       * The default TFTP port according to RFC 783 is 69.
83       ***/
84      public static final int DEFAULT_PORT = 69;
85  
86      /***
87       * The size to use for TFTP packet buffers.  Its 4 plus the
88       * TFTPPacket.SEGMENT_SIZE, i.e. 516.
89       ***/
90      static final int PACKET_SIZE = TFTPPacket.SEGMENT_SIZE + 4;
91  
92      /*** A buffer used to accelerate receives in bufferedReceive() ***/
93      private byte[] __receiveBuffer;
94  
95      /*** A datagram used to minimize memory allocation in bufferedReceive() ***/
96      private DatagramPacket __receiveDatagram;
97  
98      /*** A datagram used to minimize memory allocation in bufferedSend() ***/
99      private DatagramPacket __sendDatagram;
100 
101     /***
102      * A buffer used to accelerate sends in bufferedSend().
103      * It is left package visible so that TFTPClient may be slightly more
104      * efficient during file sends.  It saves the creation of an
105      * additional buffer and prevents a buffer copy in _newDataPcket().
106      ***/
107     byte[] _sendBuffer;
108 
109 
110     /***
111      * Returns the TFTP string representation of a TFTP transfer mode.
112      * Will throw an ArrayIndexOutOfBoundsException if an invalid transfer
113      * mode is specified.
114      *
115      * @param mode  The TFTP transfer mode.  One of the MODE constants.
116      * @return  The TFTP string representation of the TFTP transfer mode.
117      ***/
118     public static final String getModeName(int mode)
119     {
120         return TFTPRequestPacket._modeStrings[mode];
121     }
122 
123     /***
124      * Creates a TFTP instance with a default timeout of DEFAULT_TIMEOUT,
125      * a null socket, and buffered operations disabled.
126      ***/
127     public TFTP()
128     {
129         setDefaultTimeout(DEFAULT_TIMEOUT);
130         __receiveBuffer = null;
131         __receiveDatagram = null;
132     }
133 
134     /***
135      * This method synchronizes a connection by discarding all packets that
136      * may be in the local socket buffer.  This method need only be called
137      * when you implement your own TFTP client or server.
138      *
139      * @throws IOException if an I/O error occurs.
140      ***/
141     public final void discardPackets() throws IOException
142     {
143         int to;
144         DatagramPacket datagram;
145 
146         datagram = new DatagramPacket(new byte[PACKET_SIZE], PACKET_SIZE);
147 
148         to = getSoTimeout();
149         setSoTimeout(1);
150 
151         try
152         {
153             while (true) {
154                 _socket_.receive(datagram);
155             }
156         }
157         catch (SocketException e)
158         {
159             // Do nothing.  We timed out so we hope we're caught up.
160         }
161         catch (InterruptedIOException e)
162         {
163             // Do nothing.  We timed out so we hope we're caught up.
164         }
165 
166         setSoTimeout(to);
167     }
168 
169 
170     /***
171      * This is a special method to perform a more efficient packet receive.
172      * It should only be used after calling
173      * {@link #beginBufferedOps  beginBufferedOps() }.  beginBufferedOps()
174      * initializes a set of buffers used internally that prevent the new
175      * allocation of a DatagramPacket and byte array for each send and receive.
176      * To use these buffers you must call the bufferedReceive() and
177      * bufferedSend() methods instead of send() and receive().  You must
178      * also be certain that you don't manipulate the resulting packet in
179      * such a way that it interferes with future buffered operations.
180      * For example, a TFTPDataPacket received with bufferedReceive() will
181      * have a reference to the internal byte buffer.  You must finish using
182      * this data before calling bufferedReceive() again, or else the data
183      * will be overwritten by the the call.
184      *
185      * @return The TFTPPacket received.
186      * @throws InterruptedIOException  If a socket timeout occurs.  The
187      *       Java documentation claims an InterruptedIOException is thrown
188      *       on a DatagramSocket timeout, but in practice we find a
189      *       SocketException is thrown.  You should catch both to be safe.
190      * @throws SocketException  If a socket timeout occurs.  The
191      *       Java documentation claims an InterruptedIOException is thrown
192      *       on a DatagramSocket timeout, but in practice we find a
193      *       SocketException is thrown.  You should catch both to be safe.
194      * @throws IOException  If some other I/O error occurs.
195      * @throws TFTPPacketException If an invalid TFTP packet is received.
196      ***/
197     public final TFTPPacket bufferedReceive() throws IOException,
198                 InterruptedIOException, SocketException, TFTPPacketException
199     {
200         __receiveDatagram.setData(__receiveBuffer);
201         __receiveDatagram.setLength(__receiveBuffer.length);
202         _socket_.receive(__receiveDatagram);
203 
204         TFTPPacket newTFTPPacket = TFTPPacket.newTFTPPacket(__receiveDatagram);
205         trace("<", newTFTPPacket);
206         return newTFTPPacket;
207     }
208 
209     /***
210      * This is a special method to perform a more efficient packet send.
211      * It should only be used after calling
212      * {@link #beginBufferedOps  beginBufferedOps() }.  beginBufferedOps()
213      * initializes a set of buffers used internally that prevent the new
214      * allocation of a DatagramPacket and byte array for each send and receive.
215      * To use these buffers you must call the bufferedReceive() and
216      * bufferedSend() methods instead of send() and receive().  You must
217      * also be certain that you don't manipulate the resulting packet in
218      * such a way that it interferes with future buffered operations.
219      * For example, a TFTPDataPacket received with bufferedReceive() will
220      * have a reference to the internal byte buffer.  You must finish using
221      * this data before calling bufferedReceive() again, or else the data
222      * will be overwritten by the the call.
223      *
224      * @param packet  The TFTP packet to send.
225      * @throws IOException  If some  I/O error occurs.
226      ***/
227     public final void bufferedSend(TFTPPacket packet) throws IOException
228     {
229         trace(">", packet);
230         _socket_.send(packet._newDatagram(__sendDatagram, _sendBuffer));
231     }
232 
233 
234     /***
235      * Initializes the internal buffers. Buffers are used by
236      * {@link #bufferedSend  bufferedSend() } and
237      * {@link #bufferedReceive  bufferedReceive() }.  This
238      * method must be called before calling either one of those two
239      * methods.  When you finish using buffered operations, you must
240      * call {@link #endBufferedOps  endBufferedOps() }.
241      ***/
242     public final void beginBufferedOps()
243     {
244         __receiveBuffer = new byte[PACKET_SIZE];
245         __receiveDatagram =
246             new DatagramPacket(__receiveBuffer, __receiveBuffer.length);
247         _sendBuffer = new byte[PACKET_SIZE];
248         __sendDatagram =
249             new DatagramPacket(_sendBuffer, _sendBuffer.length);
250     }
251 
252     /***
253      * Releases the resources used to perform buffered sends and receives.
254      ***/
255     public final void endBufferedOps()
256     {
257         __receiveBuffer = null;
258         __receiveDatagram = null;
259         _sendBuffer = null;
260         __sendDatagram = null;
261     }
262 
263 
264     /***
265      * Sends a TFTP packet to its destination.
266      *
267      * @param packet  The TFTP packet to send.
268      * @throws IOException  If some  I/O error occurs.
269      ***/
270     public final void send(TFTPPacket packet) throws IOException
271     {
272         trace(">", packet);
273         _socket_.send(packet.newDatagram());
274     }
275 
276 
277     /***
278      * Receives a TFTPPacket.
279      *
280      * @return The TFTPPacket received.
281      * @throws InterruptedIOException  If a socket timeout occurs.  The
282      *       Java documentation claims an InterruptedIOException is thrown
283      *       on a DatagramSocket timeout, but in practice we find a
284      *       SocketException is thrown.  You should catch both to be safe.
285      * @throws SocketException  If a socket timeout occurs.  The
286      *       Java documentation claims an InterruptedIOException is thrown
287      *       on a DatagramSocket timeout, but in practice we find a
288      *       SocketException is thrown.  You should catch both to be safe.
289      * @throws IOException  If some other I/O error occurs.
290      * @throws TFTPPacketException If an invalid TFTP packet is received.
291      ***/
292     public final TFTPPacket receive() throws IOException, InterruptedIOException,
293                 SocketException, TFTPPacketException
294     {
295         DatagramPacket packet;
296 
297         packet = new DatagramPacket(new byte[PACKET_SIZE], PACKET_SIZE);
298 
299         _socket_.receive(packet);
300 
301         TFTPPacket newTFTPPacket = TFTPPacket.newTFTPPacket(packet);
302         trace("<", newTFTPPacket);
303         return newTFTPPacket;
304     }
305 
306     /**
307      * Trace facility; this implementation does nothing.
308      * <p>
309      * Override it to trace the data, for example:<br>
310      * {@code System.out.println(direction + " " + packet.toString());}
311      * @param direction ">" or "<"
312      * @param packet the packet to be sent or that has been received
313      * @since 3.6
314      */
315     protected void trace(String direction, TFTPPacket packet) {
316     }
317 
318 }