1 /*
2 * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.net;
27
28 /**
29 * This class represents a datagram packet.
30 * <p>
31 * Datagram packets are used to implement a connectionless packet
32 * delivery service. Each message is routed from one machine to
33 * another based solely on information contained within that packet.
34 * Multiple packets sent from one machine to another might be routed
35 * differently, and might arrive in any order. Packet delivery is
36 * not guaranteed.
37 *
38 * @author Pavani Diwanji
39 * @author Benjamin Renaud
40 * @since 1.0
41 */
42 public final
43 class DatagramPacket {
44
45 /**
46 * Perform class initialization
47 */
48 static {
49 java.security.AccessController.doPrivileged(
50 new java.security.PrivilegedAction<Void>() {
51 public Void run() {
52 System.loadLibrary("net");
53 return null;
54 }
55 });
56 init();
57 }
58
59 /*
60 * The fields of this class are package-private since DatagramSocketImpl
61 * classes needs to access them.
62 */
63 byte[] buf;
64 int offset;
65 int length;
66 int bufLength;
67 InetAddress address;
68 int port;
69
70 /**
71 * Constructs a {@code DatagramPacket} for receiving packets of
72 * length {@code length}, specifying an offset into the buffer.
73 * <p>
74 * The {@code length} argument must be less than or equal to
75 * {@code buf.length}.
76 *
77 * @param buf buffer for holding the incoming datagram.
78 * @param offset the offset for the buffer
79 * @param length the number of bytes to read.
80 *
81 * @since 1.2
82 */
83 public DatagramPacket(byte buf[], int offset, int length) {
84 setData(buf, offset, length);
85 this.address = null;
86 this.port = -1;
87 }
88
89 /**
90 * Constructs a {@code DatagramPacket} for receiving packets of
91 * length {@code length}.
92 * <p>
93 * The {@code length} argument must be less than or equal to
94 * {@code buf.length}.
95 *
96 * @param buf buffer for holding the incoming datagram.
97 * @param length the number of bytes to read.
98 */
99 public DatagramPacket(byte buf[], int length) {
100 this (buf, 0, length);
101 }
102
103 /**
104 * Constructs a datagram packet for sending packets of length
105 * {@code length} with offset {@code ioffset}to the
106 * specified port number on the specified host. The
107 * {@code length} argument must be less than or equal to
108 * {@code buf.length}.
109 *
110 * @param buf the packet data.
111 * @param offset the packet data offset.
112 * @param length the packet data length.
113 * @param address the destination address.
114 * @param port the destination port number.
115 * @see java.net.InetAddress
116 *
117 * @since 1.2
118 */
119 public DatagramPacket(byte buf[], int offset, int length,
120 InetAddress address, int port) {
121 setData(buf, offset, length);
122 setAddress(address);
123 setPort(port);
124 }
125
126 /**
127 * Constructs a datagram packet for sending packets of length
128 * {@code length} with offset {@code ioffset}to the
129 * specified port number on the specified host. The
130 * {@code length} argument must be less than or equal to
131 * {@code buf.length}.
132 *
133 * @param buf the packet data.
134 * @param offset the packet data offset.
135 * @param length the packet data length.
136 * @param address the destination socket address.
137 * @throws IllegalArgumentException if address type is not supported
138 * @see java.net.InetAddress
139 *
140 * @since 1.4
141 */
142 public DatagramPacket(byte buf[], int offset, int length, SocketAddress address) {
143 setData(buf, offset, length);
144 setSocketAddress(address);
145 }
146
147 /**
148 * Constructs a datagram packet for sending packets of length
149 * {@code length} to the specified port number on the specified
150 * host. The {@code length} argument must be less than or equal
151 * to {@code buf.length}.
152 *
153 * @param buf the packet data.
154 * @param length the packet length.
155 * @param address the destination address.
156 * @param port the destination port number.
157 * @see java.net.InetAddress
158 */
159 public DatagramPacket(byte buf[], int length,
160 InetAddress address, int port) {
161 this(buf, 0, length, address, port);
162 }
163
164 /**
165 * Constructs a datagram packet for sending packets of length
166 * {@code length} to the specified port number on the specified
167 * host. The {@code length} argument must be less than or equal
168 * to {@code buf.length}.
169 *
170 * @param buf the packet data.
171 * @param length the packet length.
172 * @param address the destination address.
173 * @throws IllegalArgumentException if address type is not supported
174 * @since 1.4
175 * @see java.net.InetAddress
176 */
177 public DatagramPacket(byte buf[], int length, SocketAddress address) {
178 this(buf, 0, length, address);
179 }
180
181 /**
182 * Returns the IP address of the machine to which this datagram is being
183 * sent or from which the datagram was received.
184 *
185 * @return the IP address of the machine to which this datagram is being
186 * sent or from which the datagram was received.
187 * @see java.net.InetAddress
188 * @see #setAddress(java.net.InetAddress)
189 */
190 public synchronized InetAddress getAddress() {
191 return address;
192 }
193
194 /**
195 * Returns the port number on the remote host to which this datagram is
196 * being sent or from which the datagram was received.
197 *
198 * @return the port number on the remote host to which this datagram is
199 * being sent or from which the datagram was received.
200 * @see #setPort(int)
201 */
202 public synchronized int getPort() {
203 return port;
204 }
205
206 /**
207 * Returns the data buffer. The data received or the data to be sent
208 * starts from the {@code offset} in the buffer,
209 * and runs for {@code length} long.
210 *
211 * @return the buffer used to receive or send data
212 * @see #setData(byte[], int, int)
213 */
214 public synchronized byte[] getData() {
215 return buf;
216 }
217
218 /**
219 * Returns the offset of the data to be sent or the offset of the
220 * data received.
221 *
222 * @return the offset of the data to be sent or the offset of the
223 * data received.
224 *
225 * @since 1.2
226 */
227 public synchronized int getOffset() {
228 return offset;
229 }
230
231 /**
232 * Returns the length of the data to be sent or the length of the
233 * data received.
234 *
235 * @return the length of the data to be sent or the length of the
236 * data received.
237 * @see #setLength(int)
238 */
239 public synchronized int getLength() {
240 return length;
241 }
242
243 /**
244 * Set the data buffer for this packet. This sets the
245 * data, length and offset of the packet.
246 *
247 * @param buf the buffer to set for this packet
248 *
249 * @param offset the offset into the data
250 *
251 * @param length the length of the data
252 * and/or the length of the buffer used to receive data
253 *
254 * @exception NullPointerException if the argument is null
255 *
256 * @see #getData
257 * @see #getOffset
258 * @see #getLength
259 *
260 * @since 1.2
261 */
262 public synchronized void setData(byte[] buf, int offset, int length) {
263 /* this will check to see if buf is null */
264 if (length < 0 || offset < 0 ||
265 (length + offset) < 0 ||
266 ((length + offset) > buf.length)) {
267 throw new IllegalArgumentException("illegal length or offset");
268 }
269 this.buf = buf;
270 this.length = length;
271 this.bufLength = length;
272 this.offset = offset;
273 }
274
275 /**
276 * Sets the IP address of the machine to which this datagram
277 * is being sent.
278 * @param iaddr the {@code InetAddress}
279 * @since 1.1
280 * @see #getAddress()
281 */
282 public synchronized void setAddress(InetAddress iaddr) {
283 address = iaddr;
284 }
285
286 /**
287 * Sets the port number on the remote host to which this datagram
288 * is being sent.
289 * @param iport the port number
290 * @since 1.1
291 * @see #getPort()
292 */
293 public synchronized void setPort(int iport) {
294 if (iport < 0 || iport > 0xFFFF) {
295 throw new IllegalArgumentException("Port out of range:"+ iport);
296 }
297 port = iport;
298 }
299
300 /**
301 * Sets the SocketAddress (usually IP address + port number) of the remote
302 * host to which this datagram is being sent.
303 *
304 * @param address the {@code SocketAddress}
305 * @throws IllegalArgumentException if address is null or is a
306 * SocketAddress subclass not supported by this socket
307 *
308 * @since 1.4
309 * @see #getSocketAddress
310 */
311 public synchronized void setSocketAddress(SocketAddress address) {
312 if (address == null || !(address instanceof InetSocketAddress))
313 throw new IllegalArgumentException("unsupported address type");
314 InetSocketAddress addr = (InetSocketAddress) address;
315 if (addr.isUnresolved())
316 throw new IllegalArgumentException("unresolved address");
317 setAddress(addr.getAddress());
318 setPort(addr.getPort());
319 }
320
321 /**
322 * Gets the SocketAddress (usually IP address + port number) of the remote
323 * host that this packet is being sent to or is coming from.
324 *
325 * @return the {@code SocketAddress}
326 * @since 1.4
327 * @see #setSocketAddress
328 */
329 public synchronized SocketAddress getSocketAddress() {
330 return new InetSocketAddress(getAddress(), getPort());
331 }
332
333 /**
334 * Set the data buffer for this packet. With the offset of
335 * this DatagramPacket set to 0, and the length set to
336 * the length of {@code buf}.
337 *
338 * @param buf the buffer to set for this packet.
339 *
340 * @exception NullPointerException if the argument is null.
341 *
342 * @see #getLength
343 * @see #getData
344 *
345 * @since 1.1
346 */
347 public synchronized void setData(byte[] buf) {
348 if (buf == null) {
349 throw new NullPointerException("null packet buffer");
350 }
351 this.buf = buf;
352 this.offset = 0;
353 this.length = buf.length;
354 this.bufLength = buf.length;
355 }
356
357 /**
358 * Set the length for this packet. The length of the packet is
359 * the number of bytes from the packet's data buffer that will be
360 * sent, or the number of bytes of the packet's data buffer that
361 * will be used for receiving data. The length must be lesser or
362 * equal to the offset plus the length of the packet's buffer.
363 *
364 * @param length the length to set for this packet.
365 *
366 * @exception IllegalArgumentException if the length is negative
367 * of if the length is greater than the packet's data buffer
368 * length.
369 *
370 * @see #getLength
371 * @see #setData
372 *
373 * @since 1.1
374 */
375 public synchronized void setLength(int length) {
376 if ((length + offset) > buf.length || length < 0 ||
377 (length + offset) < 0) {
378 throw new IllegalArgumentException("illegal length");
379 }
380 this.length = length;
381 this.bufLength = this.length;
382 }
383
384 /**
385 * Perform class load-time initializations.
386 */
387 private native static void init();
388 }