1 /*
2 * Copyright (c) 2007, 2009, 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 * Defines the <em>standard</em> socket options.
30 *
31 * <p> The {@link SocketOption#name name} of each socket option defined by this
32 * class is its field name.
33 *
34 * <p> In this release, the socket options defined here are used by {@link
35 * java.nio.channels.NetworkChannel network} channels in the {@link
36 * java.nio.channels channels} package.
37 *
38 * @since 1.7
39 */
40
41 public final class StandardSocketOptions {
42 private StandardSocketOptions() { }
43
44 // -- SOL_SOCKET --
45
46 /**
47 * Allow transmission of broadcast datagrams.
48 *
49 * <p> The value of this socket option is a {@code Boolean} that represents
50 * whether the option is enabled or disabled. The option is specific to
51 * datagram-oriented sockets sending to {@link java.net.Inet4Address IPv4}
52 * broadcast addresses. When the socket option is enabled then the socket
53 * can be used to send <em>broadcast datagrams</em>.
54 *
55 * <p> The initial value of this socket option is {@code FALSE}. The socket
56 * option may be enabled or disabled at any time. Some operating systems may
57 * require that the Java virtual machine be started with implementation
58 * specific privileges to enable this option or send broadcast datagrams.
59 *
60 * @see <a href="http://www.ietf.org/rfc/rfc919.txt">RFC 929:
61 * Broadcasting Internet Datagrams</a>
62 * @see DatagramSocket#setBroadcast
63 */
64 public static final SocketOption<Boolean> SO_BROADCAST =
65 new StdSocketOption<Boolean>("SO_BROADCAST", Boolean.class);
66
67 /**
68 * Keep connection alive.
69 *
70 * <p> The value of this socket option is a {@code Boolean} that represents
71 * whether the option is enabled or disabled. When the {@code SO_KEEPALIVE}
72 * option is enabled the operating system may use a <em>keep-alive</em>
73 * mechanism to periodically probe the other end of a connection when the
74 * connection is otherwise idle. The exact semantics of the keep alive
75 * mechanism is system dependent and therefore unspecified.
76 *
77 * <p> The initial value of this socket option is {@code FALSE}. The socket
78 * option may be enabled or disabled at any time.
79 *
80 * @see <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC 1122
81 * Requirements for Internet Hosts -- Communication Layers</a>
82 * @see Socket#setKeepAlive
83 */
84 public static final SocketOption<Boolean> SO_KEEPALIVE =
85 new StdSocketOption<Boolean>("SO_KEEPALIVE", Boolean.class);
86
87 /**
88 * The size of the socket send buffer.
89 *
90 * <p> The value of this socket option is an {@code Integer} that is the
91 * size of the socket send buffer in bytes. The socket send buffer is an
92 * output buffer used by the networking implementation. It may need to be
93 * increased for high-volume connections. The value of the socket option is
94 * a <em>hint</em> to the implementation to size the buffer and the actual
95 * size may differ. The socket option can be queried to retrieve the actual
96 * size.
97 *
98 * <p> For datagram-oriented sockets, the size of the send buffer may limit
99 * the size of the datagrams that may be sent by the socket. Whether
100 * datagrams larger than the buffer size are sent or discarded is system
101 * dependent.
102 *
103 * <p> The initial/default size of the socket send buffer and the range of
104 * allowable values is system dependent although a negative size is not
105 * allowed. An attempt to set the socket send buffer to larger than its
106 * maximum size causes it to be set to its maximum size.
107 *
108 * <p> An implementation allows this socket option to be set before the
109 * socket is bound or connected. Whether an implementation allows the
110 * socket send buffer to be changed after the socket is bound is system
111 * dependent.
112 *
113 * @see Socket#setSendBufferSize
114 */
115 public static final SocketOption<Integer> SO_SNDBUF =
116 new StdSocketOption<Integer>("SO_SNDBUF", Integer.class);
117
118
119 /**
120 * The size of the socket receive buffer.
121 *
122 * <p> The value of this socket option is an {@code Integer} that is the
123 * size of the socket receive buffer in bytes. The socket receive buffer is
124 * an input buffer used by the networking implementation. It may need to be
125 * increased for high-volume connections or decreased to limit the possible
126 * backlog of incoming data. The value of the socket option is a
127 * <em>hint</em> to the implementation to size the buffer and the actual
128 * size may differ.
129 *
130 * <p> For datagram-oriented sockets, the size of the receive buffer may
131 * limit the size of the datagrams that can be received. Whether datagrams
132 * larger than the buffer size can be received is system dependent.
133 * Increasing the socket receive buffer may be important for cases where
134 * datagrams arrive in bursts faster than they can be processed.
135 *
136 * <p> In the case of stream-oriented sockets and the TCP/IP protocol, the
137 * size of the socket receive buffer may be used when advertising the size
138 * of the TCP receive window to the remote peer.
139 *
140 * <p> The initial/default size of the socket receive buffer and the range
141 * of allowable values is system dependent although a negative size is not
142 * allowed. An attempt to set the socket receive buffer to larger than its
143 * maximum size causes it to be set to its maximum size.
144 *
145 * <p> An implementation allows this socket option to be set before the
146 * socket is bound or connected. Whether an implementation allows the
147 * socket receive buffer to be changed after the socket is bound is system
148 * dependent.
149 *
150 * @see <a href="http://www.ietf.org/rfc/rfc1323.txt">RFC 1323: TCP
151 * Extensions for High Performance</a>
152 * @see Socket#setReceiveBufferSize
153 * @see ServerSocket#setReceiveBufferSize
154 */
155 public static final SocketOption<Integer> SO_RCVBUF =
156 new StdSocketOption<Integer>("SO_RCVBUF", Integer.class);
157
158 /**
159 * Re-use address.
160 *
161 * <p> The value of this socket option is a {@code Boolean} that represents
162 * whether the option is enabled or disabled. The exact semantics of this
163 * socket option are socket type and system dependent.
164 *
165 * <p> In the case of stream-oriented sockets, this socket option will
166 * usually determine whether the socket can be bound to a socket address
167 * when a previous connection involving that socket address is in the
168 * <em>TIME_WAIT</em> state. On implementations where the semantics differ,
169 * and the socket option is not required to be enabled in order to bind the
170 * socket when a previous connection is in this state, then the
171 * implementation may choose to ignore this option.
172 *
173 * <p> For datagram-oriented sockets the socket option is used to allow
174 * multiple programs bind to the same address. This option should be enabled
175 * when the socket is to be used for Internet Protocol (IP) multicasting.
176 *
177 * <p> An implementation allows this socket option to be set before the
178 * socket is bound or connected. Changing the value of this socket option
179 * after the socket is bound has no effect. The default value of this
180 * socket option is system dependent.
181 *
182 * @see <a href="http://www.ietf.org/rfc/rfc793.txt">RFC 793: Transmission
183 * Control Protocol</a>
184 * @see ServerSocket#setReuseAddress
185 */
186 public static final SocketOption<Boolean> SO_REUSEADDR =
187 new StdSocketOption<Boolean>("SO_REUSEADDR", Boolean.class);
188
189 /**
190 * Linger on close if data is present.
191 *
192 * <p> The value of this socket option is an {@code Integer} that controls
193 * the action taken when unsent data is queued on the socket and a method
194 * to close the socket is invoked. If the value of the socket option is zero
195 * or greater, then it represents a timeout value, in seconds, known as the
196 * <em>linger interval</em>. The linger interval is the timeout for the
197 * {@code close} method to block while the operating system attempts to
198 * transmit the unsent data or it decides that it is unable to transmit the
199 * data. If the value of the socket option is less than zero then the option
200 * is disabled. In that case the {@code close} method does not wait until
201 * unsent data is transmitted; if possible the operating system will transmit
202 * any unsent data before the connection is closed.
203 *
204 * <p> This socket option is intended for use with sockets that are configured
205 * in {@link java.nio.channels.SelectableChannel#isBlocking() blocking} mode
206 * only. The behavior of the {@code close} method when this option is
207 * enabled on a non-blocking socket is not defined.
208 *
209 * <p> The initial value of this socket option is a negative value, meaning
210 * that the option is disabled. The option may be enabled, or the linger
211 * interval changed, at any time. The maximum value of the linger interval
212 * is system dependent. Setting the linger interval to a value that is
213 * greater than its maximum value causes the linger interval to be set to
214 * its maximum value.
215 *
216 * @see Socket#setSoLinger
217 */
218 public static final SocketOption<Integer> SO_LINGER =
219 new StdSocketOption<Integer>("SO_LINGER", Integer.class);
220
221
222 // -- IPPROTO_IP --
223
224 /**
225 * The Type of Service (ToS) octet in the Internet Protocol (IP) header.
226 *
227 * <p> The value of this socket option is an {@code Integer} representing
228 * the value of the ToS octet in IP packets sent by sockets to an {@link
229 * StandardProtocolFamily#INET IPv4} socket. The interpretation of the ToS
230 * octet is network specific and is not defined by this class. Further
231 * information on the ToS octet can be found in <a
232 * href="http://www.ietf.org/rfc/rfc1349.txt">RFC 1349</a> and <a
233 * href="http://www.ietf.org/rfc/rfc2474.txt">RFC 2474</a>. The value
234 * of the socket option is a <em>hint</em>. An implementation may ignore the
235 * value, or ignore specific values.
236 *
237 * <p> The initial/default value of the TOS field in the ToS octet is
238 * implementation specific but will typically be {@code 0}. For
239 * datagram-oriented sockets the option may be configured at any time after
240 * the socket has been bound. The new value of the octet is used when sending
241 * subsequent datagrams. It is system dependent whether this option can be
242 * queried or changed prior to binding the socket.
243 *
244 * <p> The behavior of this socket option on a stream-oriented socket, or an
245 * {@link StandardProtocolFamily#INET6 IPv6} socket, is not defined in this
246 * release.
247 *
248 * @see DatagramSocket#setTrafficClass
249 */
250 public static final SocketOption<Integer> IP_TOS =
251 new StdSocketOption<Integer>("IP_TOS", Integer.class);
252
253 /**
254 * The network interface for Internet Protocol (IP) multicast datagrams.
255 *
256 * <p> The value of this socket option is a {@link NetworkInterface} that
257 * represents the outgoing interface for multicast datagrams sent by the
258 * datagram-oriented socket. For {@link StandardProtocolFamily#INET6 IPv6}
259 * sockets then it is system dependent whether setting this option also
260 * sets the outgoing interface for multlicast datagrams sent to IPv4
261 * addresses.
262 *
263 * <p> The initial/default value of this socket option may be {@code null}
264 * to indicate that outgoing interface will be selected by the operating
265 * system, typically based on the network routing tables. An implementation
266 * allows this socket option to be set after the socket is bound. Whether
267 * the socket option can be queried or changed prior to binding the socket
268 * is system dependent.
269 *
270 * @see java.nio.channels.MulticastChannel
271 * @see MulticastSocket#setInterface
272 */
273 public static final SocketOption<NetworkInterface> IP_MULTICAST_IF =
274 new StdSocketOption<NetworkInterface>("IP_MULTICAST_IF", NetworkInterface.class);
275
276 /**
277 * The <em>time-to-live</em> for Internet Protocol (IP) multicast datagrams.
278 *
279 * <p> The value of this socket option is an {@code Integer} in the range
280 * <tt>0 <= value <= 255</tt>. It is used to control
281 * the scope of multicast datagrams sent by the datagram-oriented socket.
282 * In the case of an {@link StandardProtocolFamily#INET IPv4} socket
283 * the option is the time-to-live (TTL) on multicast datagrams sent by the
284 * socket. Datagrams with a TTL of zero are not transmitted on the network
285 * but may be delivered locally. In the case of an {@link
286 * StandardProtocolFamily#INET6 IPv6} socket the option is the
287 * <em>hop limit</em> which is number of <em>hops</em> that the datagram can
288 * pass through before expiring on the network. For IPv6 sockets it is
289 * system dependent whether the option also sets the <em>time-to-live</em>
290 * on multicast datagrams sent to IPv4 addresses.
291 *
292 * <p> The initial/default value of the time-to-live setting is typically
293 * {@code 1}. An implementation allows this socket option to be set after
294 * the socket is bound. Whether the socket option can be queried or changed
295 * prior to binding the socket is system dependent.
296 *
297 * @see java.nio.channels.MulticastChannel
298 * @see MulticastSocket#setTimeToLive
299 */
300 public static final SocketOption<Integer> IP_MULTICAST_TTL =
301 new StdSocketOption<Integer>("IP_MULTICAST_TTL", Integer.class);
302
303 /**
304 * Loopback for Internet Protocol (IP) multicast datagrams.
305 *
306 * <p> The value of this socket option is a {@code Boolean} that controls
307 * the <em>loopback</em> of multicast datagrams. The value of the socket
308 * option represents if the option is enabled or disabled.
309 *
310 * <p> The exact semantics of this socket options are system dependent.
311 * In particular, it is system dependent whether the loopback applies to
312 * multicast datagrams sent from the socket or received by the socket.
313 * For {@link StandardProtocolFamily#INET6 IPv6} sockets then it is
314 * system dependent whether the option also applies to multicast datagrams
315 * sent to IPv4 addresses.
316 *
317 * <p> The initial/default value of this socket option is {@code TRUE}. An
318 * implementation allows this socket option to be set after the socket is
319 * bound. Whether the socket option can be queried or changed prior to
320 * binding the socket is system dependent.
321 *
322 * @see java.nio.channels.MulticastChannel
323 * @see MulticastSocket#setLoopbackMode
324 */
325 public static final SocketOption<Boolean> IP_MULTICAST_LOOP =
326 new StdSocketOption<Boolean>("IP_MULTICAST_LOOP", Boolean.class);
327
328
329 // -- IPPROTO_TCP --
330
331 /**
332 * Disable the Nagle algorithm.
333 *
334 * <p> The value of this socket option is a {@code Boolean} that represents
335 * whether the option is enabled or disabled. The socket option is specific to
336 * stream-oriented sockets using the TCP/IP protocol. TCP/IP uses an algorithm
337 * known as <em>The Nagle Algorithm</em> to coalesce short segments and
338 * improve network efficiency.
339 *
340 * <p> The default value of this socket option is {@code FALSE}. The
341 * socket option should only be enabled in cases where it is known that the
342 * coalescing impacts performance. The socket option may be enabled at any
343 * time. In other words, the Nagle Algorithm can be disabled. Once the option
344 * is enabled, it is system dependent whether it can be subsequently
345 * disabled. If it cannot, then invoking the {@code setOption} method to
346 * disable the option has no effect.
347 *
348 * @see <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC 1122:
349 * Requirements for Internet Hosts -- Communication Layers</a>
350 * @see Socket#setTcpNoDelay
351 */
352 public static final SocketOption<Boolean> TCP_NODELAY =
353 new StdSocketOption<Boolean>("TCP_NODELAY", Boolean.class);
354
355
356 private static class StdSocketOption<T> implements SocketOption<T> {
357 private final String name;
358 private final Class<T> type;
359 StdSocketOption(String name, Class<T> type) {
360 this.name = name;
361 this.type = type;
362 }
363 @Override public String name() { return name; }
364 @Override public Class<T> type() { return type; }
365 @Override public String toString() { return name; }
366 }
367 }