1 /* 2 * Copyright (c) 2007, 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 * 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 multicast 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 * {@code 0 <= value <= 255}. It is used to control the scope of multicast 281 * 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 } 368
