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