/*
* Copyright (c) 2007, 2009, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package java.net;
/**
* Defines the <em>standard</em> socket options.
*
* <p> The {@link SocketOption#name name} of each socket option defined by this
* class is its field name.
*
* <p> In this release, the socket options defined here are used by {@link
* java.nio.channels.NetworkChannel network} channels in the {@link
* java.nio.channels channels} package.
*
* @since 1.7
*/
public final class StandardSocketOption {
private StandardSocketOption() { }
// -- SOL_SOCKET --
/**
* Allow transmission of broadcast datagrams.
*
* <p> The value of this socket option is a {@code Boolean} that represents
* whether the option is enabled or disabled. The option is specific to
* datagram-oriented sockets sending to {@link java.net.Inet4Address IPv4}
* broadcast addresses. When the socket option is enabled then the socket
* can be used to send <em>broadcast datagrams</em>.
*
* <p> The initial value of this socket option is {@code FALSE}. The socket
* option may be enabled or disabled at any time. Some operating systems may
* require that the Java virtual machine be started with implementation
* specific privileges to enable this option or send broadcast datagrams.
*
* @see <a href="http://www.ietf.org/rfc/rfc919.txt">RFC 929:
* Broadcasting Internet Datagrams</a>
* @see DatagramSocket#setBroadcast
*/
public static final SocketOption<Boolean> SO_BROADCAST =
new StdSocketOption<Boolean>("SO_BROADCAST", Boolean.class);
/**
* Keep connection alive.
*
* <p> The value of this socket option is a {@code Boolean} that represents
* whether the option is enabled or disabled. When the {@code SO_KEEPALIVE}
* option is enabled the operating system may use a <em>keep-alive</em>
* mechanism to periodically probe the other end of a connection when the
* connection is otherwise idle. The exact semantics of the keep alive
* mechanism is system dependent and therefore unspecified.
*
* <p> The initial value of this socket option is {@code FALSE}. The socket
* option may be enabled or disabled at any time.
*
* @see <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC 1122
* Requirements for Internet Hosts -- Communication Layers</a>
* @see Socket#setKeepAlive
*/
public static final SocketOption<Boolean> SO_KEEPALIVE =
new StdSocketOption<Boolean>("SO_KEEPALIVE", Boolean.class);
/**
* The size of the socket send buffer.
*
* <p> The value of this socket option is an {@code Integer} that is the
* size of the socket send buffer in bytes. The socket send buffer is an
* output buffer used by the networking implementation. It may need to be
* increased for high-volume connections. The value of the socket option is
* a <em>hint</em> to the implementation to size the buffer and the actual
* size may differ. The socket option can be queried to retrieve the actual
* size.
*
* <p> For datagram-oriented sockets, the size of the send buffer may limit
* the size of the datagrams that may be sent by the socket. Whether
* datagrams larger than the buffer size are sent or discarded is system
* dependent.
*
* <p> The initial/default size of the socket send buffer and the range of
* allowable values is system dependent although a negative size is not
* allowed. An attempt to set the socket send buffer to larger than its
* maximum size causes it to be set to its maximum size.
*
* <p> An implementation allows this socket option to be set before the
* socket is bound or connected. Whether an implementation allows the
* socket send buffer to be changed after the socket is bound is system
* dependent.
*
* @see Socket#setSendBufferSize
*/
public static final SocketOption<Integer> SO_SNDBUF =
new StdSocketOption<Integer>("SO_SNDBUF", Integer.class);
/**
* The size of the socket receive buffer.
*
* <p> The value of this socket option is an {@code Integer} that is the
* size of the socket receive buffer in bytes. The socket receive buffer is
* an input buffer used by the networking implementation. It may need to be
* increased for high-volume connections or decreased to limit the possible
* backlog of incoming data. The value of the socket option is a
* <em>hint</em> to the implementation to size the buffer and the actual
* size may differ.
*
* <p> For datagram-oriented sockets, the size of the receive buffer may
* limit the size of the datagrams that can be received. Whether datagrams
* larger than the buffer size can be received is system dependent.
* Increasing the socket receive buffer may be important for cases where
* datagrams arrive in bursts faster than they can be processed.
*
* <p> In the case of stream-oriented sockets and the TCP/IP protocol, the
* size of the socket receive buffer may be used when advertising the size
* of the TCP receive window to the remote peer.
*
* <p> The initial/default size of the socket receive buffer and the range
* of allowable values is system dependent although a negative size is not
* allowed. An attempt to set the socket receive buffer to larger than its
* maximum size causes it to be set to its maximum size.
*
* <p> An implementation allows this socket option to be set before the
* socket is bound or connected. Whether an implementation allows the
* socket receive buffer to be changed after the socket is bound is system
* dependent.
*
* @see <a href="http://www.ietf.org/rfc/rfc1323.txt">RFC 1323: TCP
* Extensions for High Performance</a>
* @see Socket#setReceiveBufferSize
* @see ServerSocket#setReceiveBufferSize
*/
public static final SocketOption<Integer> SO_RCVBUF =
new StdSocketOption<Integer>("SO_RCVBUF", Integer.class);
/**
* Re-use address.
*
* <p> The value of this socket option is a {@code Boolean} that represents
* whether the option is enabled or disabled. The exact semantics of this
* socket option are socket type and system dependent.
*
* <p> In the case of stream-oriented sockets, this socket option will
* usually determine whether the socket can be bound to a socket address
* when a previous connection involving that socket address is in the
* <em>TIME_WAIT</em> state. On implementations where the semantics differ,
* and the socket option is not required to be enabled in order to bind the
* socket when a previous connection is in this state, then the
* implementation may choose to ignore this option.
*
* <p> For datagram-oriented sockets the socket option is used to allow
* multiple programs bind to the same address. This option should be enabled
* when the socket is to be used for Internet Protocol (IP) multicasting.
*
* <p> An implementation allows this socket option to be set before the
* socket is bound or connected. Changing the value of this socket option
* after the socket is bound has no effect. The default value of this
* socket option is system dependent.
*
* @see <a href="http://www.ietf.org/rfc/rfc793.txt">RFC 793: Transmission
* Control Protocol</a>
* @see ServerSocket#setReuseAddress
*/
public static final SocketOption<Boolean> SO_REUSEADDR =
new StdSocketOption<Boolean>("SO_REUSEADDR", Boolean.class);
/**
* Linger on close if data is present.
*
* <p> The value of this socket option is an {@code Integer} that controls
* the action taken when unsent data is queued on the socket and a method
* to close the socket is invoked. If the value of the socket option is zero
* or greater, then it represents a timeout value, in seconds, known as the
* <em>linger interval</em>. The linger interval is the timeout for the
* {@code close} method to block while the operating system attempts to
* transmit the unsent data or it decides that it is unable to transmit the
* data. If the value of the socket option is less than zero then the option
* is disabled. In that case the {@code close} method does not wait until
* unsent data is transmitted; if possible the operating system will transmit
* any unsent data before the connection is closed.
*
* <p> This socket option is intended for use with sockets that are configured
* in {@link java.nio.channels.SelectableChannel#isBlocking() blocking} mode
* only. The behavior of the {@code close} method when this option is
* enabled on a non-blocking socket is not defined.
*
* <p> The initial value of this socket option is a negative value, meaning
* that the option is disabled. The option may be enabled, or the linger
* interval changed, at any time. The maximum value of the linger interval
* is system dependent. Setting the linger interval to a value that is
* greater than its maximum value causes the linger interval to be set to
* its maximum value.
*
* @see Socket#setSoLinger
*/
public static final SocketOption<Integer> SO_LINGER =
new StdSocketOption<Integer>("SO_LINGER", Integer.class);
// -- IPPROTO_IP --
/**
* The Type of Service (ToS) octet in the Internet Protocol (IP) header.
*
* <p> The value of this socket option is an {@code Integer} representing
* the value of the ToS octet in IP packets sent by sockets to an {@link
* StandardProtocolFamily#INET IPv4} socket. The interpretation of the ToS
* octet is network specific and is not defined by this class. Further
* information on the ToS octet can be found in <a
* href="http://www.ietf.org/rfc/rfc1349.txt">RFC 1349</a> and <a
* href="http://www.ietf.org/rfc/rfc2474.txt">RFC 2474</a>. The value
* of the socket option is a <em>hint</em>. An implementation may ignore the
* value, or ignore specific values.
*
* <p> The initial/default value of the TOS field in the ToS octet is
* implementation specific but will typically be {@code 0}. For
* datagram-oriented sockets the option may be configured at any time after
* the socket has been bound. The new value of the octet is used when sending
* subsequent datagrams. It is system dependent whether this option can be
* queried or changed prior to binding the socket.
*
* <p> The behavior of this socket option on a stream-oriented socket, or an
* {@link StandardProtocolFamily#INET6 IPv6} socket, is not defined in this
* release.
*
* @see DatagramSocket#setTrafficClass
*/
public static final SocketOption<Integer> IP_TOS =
new StdSocketOption<Integer>("IP_TOS", Integer.class);
/**
* The network interface for Internet Protocol (IP) multicast datagrams.
*
* <p> The value of this socket option is a {@link NetworkInterface} that
* represents the outgoing interface for multicast datagrams sent by the
* datagram-oriented socket. For {@link StandardProtocolFamily#INET6 IPv6}
* sockets then it is system dependent whether setting this option also
* sets the outgoing interface for multlicast datagrams sent to IPv4
* addresses.
*
* <p> The initial/default value of this socket option may be {@code null}
* to indicate that outgoing interface will be selected by the operating
* system, typically based on the network routing tables. An implementation
* allows this socket option to be set after the socket is bound. Whether
* the socket option can be queried or changed prior to binding the socket
* is system dependent.
*
* @see java.nio.channels.MulticastChannel
* @see MulticastSocket#setInterface
*/
public static final SocketOption<NetworkInterface> IP_MULTICAST_IF =
new StdSocketOption<NetworkInterface>("IP_MULTICAST_IF", NetworkInterface.class);
/**
* The <em>time-to-live</em> for Internet Protocol (IP) multicast datagrams.
*
* <p> The value of this socket option is an {@code Integer} in the range
* <tt>0 <= value <= 255</tt>. It is used to control
* the scope of multicast datagrams sent by the datagram-oriented socket.
* In the case of an {@link StandardProtocolFamily#INET IPv4} socket
* the option is the time-to-live (TTL) on multicast datagrams sent by the
* socket. Datagrams with a TTL of zero are not transmitted on the network
* but may be delivered locally. In the case of an {@link
* StandardProtocolFamily#INET6 IPv6} socket the option is the
* <em>hop limit</em> which is number of <em>hops</em> that the datagram can
* pass through before expiring on the network. For IPv6 sockets it is
* system dependent whether the option also sets the <em>time-to-live</em>
* on multicast datagrams sent to IPv4 addresses.
*
* <p> The initial/default value of the time-to-live setting is typically
* {@code 1}. An implementation allows this socket option to be set after
* the socket is bound. Whether the socket option can be queried or changed
* prior to binding the socket is system dependent.
*
* @see java.nio.channels.MulticastChannel
* @see MulticastSocket#setTimeToLive
*/
public static final SocketOption<Integer> IP_MULTICAST_TTL =
new StdSocketOption<Integer>("IP_MULTICAST_TTL", Integer.class);
/**
* Loopback for Internet Protocol (IP) multicast datagrams.
*
* <p> The value of this socket option is a {@code Boolean} that controls
* the <em>loopback</em> of multicast datagrams. The value of the socket
* option represents if the option is enabled or disabled.
*
* <p> The exact semantics of this socket options are system dependent.
* In particular, it is system dependent whether the loopback applies to
* multicast datagrams sent from the socket or received by the socket.
* For {@link StandardProtocolFamily#INET6 IPv6} sockets then it is
* system dependent whether the option also applies to multicast datagrams
* sent to IPv4 addresses.
*
* <p> The initial/default value of this socket option is {@code TRUE}. An
* implementation allows this socket option to be set after the socket is
* bound. Whether the socket option can be queried or changed prior to
* binding the socket is system dependent.
*
* @see java.nio.channels.MulticastChannel
* @see MulticastSocket#setLoopbackMode
*/
public static final SocketOption<Boolean> IP_MULTICAST_LOOP =
new StdSocketOption<Boolean>("IP_MULTICAST_LOOP", Boolean.class);
// -- IPPROTO_TCP --
/**
* Disable the Nagle algorithm.
*
* <p> The value of this socket option is a {@code Boolean} that represents
* whether the option is enabled or disabled. The socket option is specific to
* stream-oriented sockets using the TCP/IP protocol. TCP/IP uses an algorithm
* known as <em>The Nagle Algorithm</em> to coalesce short segments and
* improve network efficiency.
*
* <p> The default value of this socket option is {@code FALSE}. The
* socket option should only be enabled in cases where it is known that the
* coalescing impacts performance. The socket option may be enabled at any
* time. In other words, the Nagle Algorithm can be disabled. Once the option
* is enabled, it is system dependent whether it can be subsequently
* disabled. If it cannot, then invoking the {@code setOption} method to
* disable the option has no effect.
*
* @see <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC 1122:
* Requirements for Internet Hosts -- Communication Layers</a>
* @see Socket#setTcpNoDelay
*/
public static final SocketOption<Boolean> TCP_NODELAY =
new StdSocketOption<Boolean>("TCP_NODELAY", Boolean.class);
private static class StdSocketOption<T> implements SocketOption<T> {
private final String name;
private final Class<T> type;
StdSocketOption(String name, Class<T> type) {
this.name = name;
this.type = type;
}
@Override public String name() { return name; }
@Override public Class<T> type() { return type; }
@Override public String toString() { return name; }
}
}