1 /*
2 * Copyright (c) 1996, 2016, 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 import java.lang.annotation.Native;
29
30 /**
31 * Interface of methods to get/set socket options. This interface is
32 * implemented by: <B>SocketImpl</B> and <B>DatagramSocketImpl</B>.
33 * Subclasses of these should override the methods
34 * of this interface in order to support their own options.
35 * <P>
36 * The methods and constants which specify options in this interface are
37 * for implementation only. If you're not subclassing SocketImpl or
38 * DatagramSocketImpl, <B>you won't use these directly.</B> There are
39 * type-safe methods to get/set each of these options in Socket, ServerSocket,
40 * DatagramSocket and MulticastSocket.
41 *
42 * @author David Brown
43 */
44
45
46 public interface SocketOptions {
47
48 /**
49 * Enable/disable the option specified by <I>optID</I>. If the option
50 * is to be enabled, and it takes an option-specific "value", this is
51 * passed in <I>value</I>. The actual type of value is option-specific,
52 * and it is an error to pass something that isn't of the expected type:
53 * <BR><PRE>
54 * SocketImpl s;
55 * ...
56 * s.setOption(SO_LINGER, new Integer(10));
57 * // OK - set SO_LINGER w/ timeout of 10 sec.
58 * s.setOption(SO_LINGER, new Double(10));
59 * // ERROR - expects java.lang.Integer
60 *</PRE>
61 * If the requested option is binary, it can be set using this method by
62 * a java.lang.Boolean:
63 * <BR><PRE>
64 * s.setOption(TCP_NODELAY, Boolean.TRUE);
65 * // OK - enables TCP_NODELAY, a binary option
66 * </PRE>
67 * <BR>
68 * Any option can be disabled using this method with a Boolean.FALSE:
69 * <BR><PRE>
70 * s.setOption(TCP_NODELAY, Boolean.FALSE);
71 * // OK - disables TCP_NODELAY
72 * s.setOption(SO_LINGER, Boolean.FALSE);
73 * // OK - disables SO_LINGER
74 * </PRE>
75 * <BR>
76 * For an option that has a notion of on and off, and requires
77 * a non-boolean parameter, setting its value to anything other than
78 * <I>Boolean.FALSE</I> implicitly enables it.
79 * <BR>
80 * Throws SocketException if the option is unrecognized,
81 * the socket is closed, or some low-level error occurred
82 * <BR>
83 * @param optID identifies the option
84 * @param value the parameter of the socket option
85 * @throws SocketException if the option is unrecognized,
86 * the socket is closed, or some low-level error occurred
87 * @see #getOption(int)
88 */
89 public void
90 setOption(int optID, Object value) throws SocketException;
91
92 /**
93 * Fetch the value of an option.
94 * Binary options will return java.lang.Boolean.TRUE
95 * if enabled, java.lang.Boolean.FALSE if disabled, e.g.:
96 * <BR><PRE>
97 * SocketImpl s;
98 * ...
99 * Boolean noDelay = (Boolean)(s.getOption(TCP_NODELAY));
100 * if (noDelay.booleanValue()) {
101 * // true if TCP_NODELAY is enabled...
102 * ...
103 * }
104 * </PRE>
105 * <P>
106 * For options that take a particular type as a parameter,
107 * getOption(int) will return the parameter's value, else
108 * it will return java.lang.Boolean.FALSE:
109 * <PRE>
110 * Object o = s.getOption(SO_LINGER);
111 * if (o instanceof Integer) {
112 * System.out.print("Linger time is " + ((Integer)o).intValue());
113 * } else {
114 * // the true type of o is java.lang.Boolean.FALSE;
115 * }
116 * </PRE>
117 *
118 * @param optID an {@code int} identifying the option to fetch
119 * @return the value of the option
120 * @throws SocketException if the socket is closed
121 * @throws SocketException if <I>optID</I> is unknown along the
122 * protocol stack (including the SocketImpl)
123 * @see #setOption(int, java.lang.Object)
124 */
125 public Object getOption(int optID) throws SocketException;
126
127 /**
128 * The java-supported BSD-style options.
129 */
130
131 /**
132 * Disable Nagle's algorithm for this connection. Written data
133 * to the network is not buffered pending acknowledgement of
134 * previously written data.
135 *<P>
136 * Valid for TCP only: SocketImpl.
137 *
138 * @see Socket#setTcpNoDelay
139 * @see Socket#getTcpNoDelay
140 */
141
142 @Native public static final int TCP_NODELAY = 0x0001;
143
144 /**
145 * Fetch the local address binding of a socket (this option cannot
146 * be "set" only "gotten", since sockets are bound at creation time,
147 * and so the locally bound address cannot be changed). The default local
148 * address of a socket is INADDR_ANY, meaning any local address on a
149 * multi-homed host. A multi-homed host can use this option to accept
150 * connections to only one of its addresses (in the case of a
151 * ServerSocket or DatagramSocket), or to specify its return address
152 * to the peer (for a Socket or DatagramSocket). The parameter of
153 * this option is an InetAddress.
154 * <P>
155 * This option <B>must</B> be specified in the constructor.
156 * <P>
157 * Valid for: SocketImpl, DatagramSocketImpl
158 *
159 * @see Socket#getLocalAddress
160 * @see DatagramSocket#getLocalAddress
161 */
162
163 @Native public static final int SO_BINDADDR = 0x000F;
164
165 /** Sets SO_REUSEADDR for a socket. This is used only for MulticastSockets
166 * in java, and it is set by default for MulticastSockets.
167 * <P>
168 * Valid for: DatagramSocketImpl
169 */
170
171 @Native public static final int SO_REUSEADDR = 0x04;
172
173 /** Sets SO_REUSEPORT for a socket. This option enables and disables
174 * the ability to have multiple sockets listen to the same address
175 * and port.
176 * <P>
177 * Valid for: SocketImpl, DatagramSocketImpl
178 *
179 * @since 9
180 * @see StandardSocketOptions#SO_REUSEPORT
181 */
182 @Native public static final int SO_REUSEPORT = 0x0E;
183
184 /**
185 * Sets SO_BROADCAST for a socket. This option enables and disables
186 * the ability of the process to send broadcast messages. It is supported
187 * for only datagram sockets and only on networks that support
188 * the concept of a broadcast message (e.g. Ethernet, token ring, etc.),
189 * and it is set by default for DatagramSockets.
190 * @since 1.4
191 */
192
193 @Native public static final int SO_BROADCAST = 0x0020;
194
195 /** Set which outgoing interface on which to send multicast packets.
196 * Useful on hosts with multiple network interfaces, where applications
197 * want to use other than the system default. Takes/returns an InetAddress.
198 * <P>
199 * Valid for Multicast: DatagramSocketImpl
200 *
201 * @see MulticastSocket#setInterface(InetAddress)
202 * @see MulticastSocket#getInterface()
203 */
204
205 @Native public static final int IP_MULTICAST_IF = 0x10;
206
207 /** Same as above. This option is introduced so that the behaviour
208 * with IP_MULTICAST_IF will be kept the same as before, while
209 * this new option can support setting outgoing interfaces with either
210 * IPv4 and IPv6 addresses.
211 *
212 * NOTE: make sure there is no conflict with this
213 * @see MulticastSocket#setNetworkInterface(NetworkInterface)
214 * @see MulticastSocket#getNetworkInterface()
215 * @since 1.4
216 */
217 @Native public static final int IP_MULTICAST_IF2 = 0x1f;
218
219 /**
220 * This option enables or disables local loopback of multicast datagrams.
221 * This option is enabled by default for Multicast Sockets.
222 * @since 1.4
223 */
224
225 @Native public static final int IP_MULTICAST_LOOP = 0x12;
226
227 /**
228 * This option sets the type-of-service or traffic class field
229 * in the IP header for a TCP or UDP socket.
230 * @since 1.4
231 */
232
233 @Native public static final int IP_TOS = 0x3;
234
235 /**
236 * Specify a linger-on-close timeout. This option disables/enables
237 * immediate return from a <B>close()</B> of a TCP Socket. Enabling
238 * this option with a non-zero Integer <I>timeout</I> means that a
239 * <B>close()</B> will block pending the transmission and acknowledgement
240 * of all data written to the peer, at which point the socket is closed
241 * <I>gracefully</I>. Upon reaching the linger timeout, the socket is
242 * closed <I>forcefully</I>, with a TCP RST. Enabling the option with a
243 * timeout of zero does a forceful close immediately. If the specified
244 * timeout value exceeds 65,535 it will be reduced to 65,535.
245 * <P>
246 * Valid only for TCP: SocketImpl
247 *
248 * @see Socket#setSoLinger
249 * @see Socket#getSoLinger
250 */
251 @Native public static final int SO_LINGER = 0x0080;
252
253 /** Set a timeout on blocking Socket operations:
254 * <PRE>
255 * ServerSocket.accept();
256 * SocketInputStream.read();
257 * DatagramSocket.receive();
258 * </PRE>
259 *
260 * <P> The option must be set prior to entering a blocking
261 * operation to take effect. If the timeout expires and the
262 * operation would continue to block,
263 * <B>java.io.InterruptedIOException</B> is raised. The Socket is
264 * not closed in this case.
265 *
266 * <P> Valid for all sockets: SocketImpl, DatagramSocketImpl
267 *
268 * @see Socket#setSoTimeout
269 * @see ServerSocket#setSoTimeout
270 * @see DatagramSocket#setSoTimeout
271 */
272 @Native public static final int SO_TIMEOUT = 0x1006;
273
274 /**
275 * Set a hint the size of the underlying buffers used by the
276 * platform for outgoing network I/O. When used in set, this is a
277 * suggestion to the kernel from the application about the size of
278 * buffers to use for the data to be sent over the socket. When
279 * used in get, this must return the size of the buffer actually
280 * used by the platform when sending out data on this socket.
281 *
282 * Valid for all sockets: SocketImpl, DatagramSocketImpl
283 *
284 * @see Socket#setSendBufferSize
285 * @see Socket#getSendBufferSize
286 * @see DatagramSocket#setSendBufferSize
287 * @see DatagramSocket#getSendBufferSize
288 */
289 @Native public static final int SO_SNDBUF = 0x1001;
290
291 /**
292 * Set a hint the size of the underlying buffers used by the
293 * platform for incoming network I/O. When used in set, this is a
294 * suggestion to the kernel from the application about the size of
295 * buffers to use for the data to be received over the
296 * socket. When used in get, this must return the size of the
297 * buffer actually used by the platform when receiving in data on
298 * this socket.
299 *
300 * Valid for all sockets: SocketImpl, DatagramSocketImpl
301 *
302 * @see Socket#setReceiveBufferSize
303 * @see Socket#getReceiveBufferSize
304 * @see DatagramSocket#setReceiveBufferSize
305 * @see DatagramSocket#getReceiveBufferSize
306 */
307 @Native public static final int SO_RCVBUF = 0x1002;
308
309 /**
310 * When the keepalive option is set for a TCP socket and no data
311 * has been exchanged across the socket in either direction for
312 * 2 hours (NOTE: the actual value is implementation dependent),
313 * TCP automatically sends a keepalive probe to the peer. This probe is a
314 * TCP segment to which the peer must respond.
315 * One of three responses is expected:
316 * 1. The peer responds with the expected ACK. The application is not
317 * notified (since everything is OK). TCP will send another probe
318 * following another 2 hours of inactivity.
319 * 2. The peer responds with an RST, which tells the local TCP that
320 * the peer host has crashed and rebooted. The socket is closed.
321 * 3. There is no response from the peer. The socket is closed.
322 *
323 * The purpose of this option is to detect if the peer host crashes.
324 *
325 * Valid only for TCP socket: SocketImpl
326 *
327 * @see Socket#setKeepAlive
328 * @see Socket#getKeepAlive
329 */
330 @Native public static final int SO_KEEPALIVE = 0x0008;
331
332 /**
333 * When the OOBINLINE option is set, any TCP urgent data received on
334 * the socket will be received through the socket input stream.
335 * When the option is disabled (which is the default) urgent data
336 * is silently discarded.
337 *
338 * @see Socket#setOOBInline
339 * @see Socket#getOOBInline
340 */
341 @Native public static final int SO_OOBINLINE = 0x1003;
342 }