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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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 StandardSocketOptions {

    private StandardSocketOptions() { }

    // -- 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&nbsp;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&nbsp;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&nbsp;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&nbsp;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&nbsp;1349</a> and <a

     * href="http://www.ietf.org/rfc/rfc2474.txt">RFC&nbsp;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 multicast 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

     * {@code 0 <= value <= 255}. 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&nbsp;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; }

    }

}