Back to index...

	/*
	* Copyright (c) 1996, 2013, 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
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.net;

	import java.lang.annotation.Native;

	/**
	* Interface of methods to get/set socket options. This interface is
	* implemented by: <B>SocketImpl</B> and <B>DatagramSocketImpl</B>.
	* Subclasses of these should override the methods
	* of this interface in order to support their own options.
	* <P>
	* The methods and constants which specify options in this interface are
	* for implementation only. If you're not subclassing SocketImpl or
	* DatagramSocketImpl, <B>you won't use these directly.</B> There are
	* type-safe methods to get/set each of these options in Socket, ServerSocket,
	* DatagramSocket and MulticastSocket.
	* <P>
	* @author David Brown
	*/


	public interface SocketOptions {

	/**
	* Enable/disable the option specified by <I>optID</I>. If the option
	* is to be enabled, and it takes an option-specific "value", this is
	* passed in <I>value</I>. The actual type of value is option-specific,
	* and it is an error to pass something that isn't of the expected type:
	* <BR><PRE>
	* SocketImpl s;
	* ...
	* s.setOption(SO_LINGER, new Integer(10));
	* // OK - set SO_LINGER w/ timeout of 10 sec.
	* s.setOption(SO_LINGER, new Double(10));
	* // ERROR - expects java.lang.Integer
	*</PRE>
	* If the requested option is binary, it can be set using this method by
	* a java.lang.Boolean:
	* <BR><PRE>
	* s.setOption(TCP_NODELAY, new Boolean(true));
	* // OK - enables TCP_NODELAY, a binary option
	* </PRE>
	* <BR>
	* Any option can be disabled using this method with a Boolean(false):
	* <BR><PRE>
	* s.setOption(TCP_NODELAY, new Boolean(false));
	* // OK - disables TCP_NODELAY
	* s.setOption(SO_LINGER, new Boolean(false));
	* // OK - disables SO_LINGER
	* </PRE>
	* <BR>
	* For an option that has a notion of on and off, and requires
	* a non-boolean parameter, setting its value to anything other than
	* <I>Boolean(false)</I> implicitly enables it.
	* <BR>
	* Throws SocketException if the option is unrecognized,
	* the socket is closed, or some low-level error occurred
	* <BR>
	* @param optID identifies the option
	* @param value the parameter of the socket option
	* @throws SocketException if the option is unrecognized,
	* the socket is closed, or some low-level error occurred
	* @see #getOption(int)
	*/
	public void
	setOption(int optID, Object value) throws SocketException;

	/**
	* Fetch the value of an option.
	* Binary options will return java.lang.Boolean(true)
	* if enabled, java.lang.Boolean(false) if disabled, e.g.:
	* <BR><PRE>
	* SocketImpl s;
	* ...
	* Boolean noDelay = (Boolean)(s.getOption(TCP_NODELAY));
	* if (noDelay.booleanValue()) {
	* // true if TCP_NODELAY is enabled...
	* ...
	* }
	* </PRE>
	* <P>
	* For options that take a particular type as a parameter,
	* getOption(int) will return the parameter's value, else
	* it will return java.lang.Boolean(false):
	* <PRE>
	* Object o = s.getOption(SO_LINGER);
	* if (o instanceof Integer) {
	* System.out.print("Linger time is " + ((Integer)o).intValue());
	* } else {
	* // the true type of o is java.lang.Boolean(false);
	* }
	* </PRE>
	*
	* @param optID an {@code int} identifying the option to fetch
	* @return the value of the option
	* @throws SocketException if the socket is closed
	* @throws SocketException if <I>optID</I> is unknown along the
	* protocol stack (including the SocketImpl)
	* @see #setOption(int, java.lang.Object)
	*/
	public Object getOption(int optID) throws SocketException;

	/**
	* The java-supported BSD-style options.
	*/

	/**
	* Disable Nagle's algorithm for this connection. Written data
	* to the network is not buffered pending acknowledgement of
	* previously written data.
	*<P>
	* Valid for TCP only: SocketImpl.
	*
	* @see Socket#setTcpNoDelay
	* @see Socket#getTcpNoDelay
	*/

	@Native public final static int TCP_NODELAY = 0x0001;

	/**
	* Fetch the local address binding of a socket (this option cannot
	* be "set" only "gotten", since sockets are bound at creation time,
	* and so the locally bound address cannot be changed). The default local
	* address of a socket is INADDR_ANY, meaning any local address on a
	* multi-homed host. A multi-homed host can use this option to accept
	* connections to only one of its addresses (in the case of a
	* ServerSocket or DatagramSocket), or to specify its return address
	* to the peer (for a Socket or DatagramSocket). The parameter of
	* this option is an InetAddress.
	* <P>
	* This option <B>must</B> be specified in the constructor.
	* <P>
	* Valid for: SocketImpl, DatagramSocketImpl
	*
	* @see Socket#getLocalAddress
	* @see DatagramSocket#getLocalAddress
	*/

	@Native public final static int SO_BINDADDR = 0x000F;

	/** Sets SO_REUSEADDR for a socket. This is used only for MulticastSockets
	* in java, and it is set by default for MulticastSockets.
	* <P>
	* Valid for: DatagramSocketImpl
	*/

	@Native public final static int SO_REUSEADDR = 0x04;

	/**
	* Sets SO_BROADCAST for a socket. This option enables and disables
	* the ability of the process to send broadcast messages. It is supported
	* for only datagram sockets and only on networks that support
	* the concept of a broadcast message (e.g. Ethernet, token ring, etc.),
	* and it is set by default for DatagramSockets.
	* @since 1.4
	*/

	@Native public final static int SO_BROADCAST = 0x0020;

	/** Set which outgoing interface on which to send multicast packets.
	* Useful on hosts with multiple network interfaces, where applications
	* want to use other than the system default. Takes/returns an InetAddress.
	* <P>
	* Valid for Multicast: DatagramSocketImpl
	*
	* @see MulticastSocket#setInterface(InetAddress)
	* @see MulticastSocket#getInterface()
	*/

	@Native public final static int IP_MULTICAST_IF = 0x10;

	/** Same as above. This option is introduced so that the behaviour
	* with IP_MULTICAST_IF will be kept the same as before, while
	* this new option can support setting outgoing interfaces with either
	* IPv4 and IPv6 addresses.
	*
	* NOTE: make sure there is no conflict with this
	* @see MulticastSocket#setNetworkInterface(NetworkInterface)
	* @see MulticastSocket#getNetworkInterface()
	* @since 1.4
	*/
	@Native public final static int IP_MULTICAST_IF2 = 0x1f;

	/**
	* This option enables or disables local loopback of multicast datagrams.
	* This option is enabled by default for Multicast Sockets.
	* @since 1.4
	*/

	@Native public final static int IP_MULTICAST_LOOP = 0x12;

	/**
	* This option sets the type-of-service or traffic class field
	* in the IP header for a TCP or UDP socket.
	* @since 1.4
	*/

	@Native public final static int IP_TOS = 0x3;

	/**
	* Specify a linger-on-close timeout. This option disables/enables
	* immediate return from a <B>close()</B> of a TCP Socket. Enabling
	* this option with a non-zero Integer <I>timeout</I> means that a
	* <B>close()</B> will block pending the transmission and acknowledgement
	* of all data written to the peer, at which point the socket is closed
	* <I>gracefully</I>. Upon reaching the linger timeout, the socket is
	* closed <I>forcefully</I>, with a TCP RST. Enabling the option with a
	* timeout of zero does a forceful close immediately. If the specified
	* timeout value exceeds 65,535 it will be reduced to 65,535.
	* <P>
	* Valid only for TCP: SocketImpl
	*
	* @see Socket#setSoLinger
	* @see Socket#getSoLinger
	*/
	@Native public final static int SO_LINGER = 0x0080;

	/** Set a timeout on blocking Socket operations:
	* <PRE>
	* ServerSocket.accept();
	* SocketInputStream.read();
	* DatagramSocket.receive();
	* </PRE>
	*
	* <P> The option must be set prior to entering a blocking
	* operation to take effect. If the timeout expires and the
	* operation would continue to block,
	* <B>java.io.InterruptedIOException</B> is raised. The Socket is
	* not closed in this case.
	*
	* <P> Valid for all sockets: SocketImpl, DatagramSocketImpl
	*
	* @see Socket#setSoTimeout
	* @see ServerSocket#setSoTimeout
	* @see DatagramSocket#setSoTimeout
	*/
	@Native public final static int SO_TIMEOUT = 0x1006;

	/**
	* Set a hint the size of the underlying buffers used by the
	* platform for outgoing network I/O. When used in set, this is a
	* suggestion to the kernel from the application about the size of
	* buffers to use for the data to be sent over the socket. When
	* used in get, this must return the size of the buffer actually
	* used by the platform when sending out data on this socket.
	*
	* Valid for all sockets: SocketImpl, DatagramSocketImpl
	*
	* @see Socket#setSendBufferSize
	* @see Socket#getSendBufferSize
	* @see DatagramSocket#setSendBufferSize
	* @see DatagramSocket#getSendBufferSize
	*/
	@Native public final static int SO_SNDBUF = 0x1001;

	/**
	* Set a hint the size of the underlying buffers used by the
	* platform for incoming network I/O. When used in set, this is a
	* suggestion to the kernel from the application about the size of
	* buffers to use for the data to be received over the
	* socket. When used in get, this must return the size of the
	* buffer actually used by the platform when receiving in data on
	* this socket.
	*
	* Valid for all sockets: SocketImpl, DatagramSocketImpl
	*
	* @see Socket#setReceiveBufferSize
	* @see Socket#getReceiveBufferSize
	* @see DatagramSocket#setReceiveBufferSize
	* @see DatagramSocket#getReceiveBufferSize
	*/
	@Native public final static int SO_RCVBUF = 0x1002;

	/**
	* When the keepalive option is set for a TCP socket and no data
	* has been exchanged across the socket in either direction for
	* 2 hours (NOTE: the actual value is implementation dependent),
	* TCP automatically sends a keepalive probe to the peer. This probe is a
	* TCP segment to which the peer must respond.
	* One of three responses is expected:
	* 1. The peer responds with the expected ACK. The application is not
	* notified (since everything is OK). TCP will send another probe
	* following another 2 hours of inactivity.
	* 2. The peer responds with an RST, which tells the local TCP that
	* the peer host has crashed and rebooted. The socket is closed.
	* 3. There is no response from the peer. The socket is closed.
	*
	* The purpose of this option is to detect if the peer host crashes.
	*
	* Valid only for TCP socket: SocketImpl
	*
	* @see Socket#setKeepAlive
	* @see Socket#getKeepAlive
	*/
	@Native public final static int SO_KEEPALIVE = 0x0008;

	/**
	* When the OOBINLINE option is set, any TCP urgent data received on
	* the socket will be received through the socket input stream.
	* When the option is disabled (which is the default) urgent data
	* is silently discarded.
	*
	* @see Socket#setOOBInline
	* @see Socket#getOOBInline
	*/
	@Native public final static int SO_OOBINLINE = 0x1003;
	}

Back to index...