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 * Copyright (c) 2007, 2016, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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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);

 /**
 * Re-use port.
 *
 * <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 usually allows
 * multiple listening sockets to be bound to both same address
 * and same port.
 *
 * <p> For datagram-oriented sockets the socket option usually allows
 * multiple UDP sockets to be bound to the same address and port.
 *
 * <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.
 *
 * @since 9
 */
 public static final SocketOption<Boolean> SO_REUSEPORT =
 new StdSocketOption<Boolean>("SO_REUSEPORT", 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; }
 }
}