1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   5  * This code is free software; you can redistribute it and/or modify it
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   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.
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  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).
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  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  23  * questions.
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  25 
  26 package java.net;
  27 
  28 /**
  29  * Interface of methods to get/set socket options.  This interface is
  30  * implemented by: <B>SocketImpl</B> and  <B>DatagramSocketImpl</B>.
  31  * Subclasses of these should override the methods
  32  * of this interface in order to support their own options.
  33  * <P>
  34  * The methods and constants which specify options in this interface are
  35  * for implementation only.  If you're not subclassing SocketImpl or
  36  * DatagramSocketImpl, <B>you won't use these directly.</B> There are
  37  * type-safe methods to get/set each of these options in Socket, ServerSocket,
  38  * DatagramSocket and MulticastSocket.
  39  * <P>
  40  * @author David Brown
  41  */
  42 
  43 
  44 public interface SocketOptions {
  45 
  46     /**
  47      * Enable/disable the option specified by <I>optID</I>.  If the option
  48      * is to be enabled, and it takes an option-specific "value",  this is
  49      * passed in <I>value</I>.  The actual type of value is option-specific,
  50      * and it is an error to pass something that isn't of the expected type:
  51      * <BR><PRE>
  52      * SocketImpl s;
  53      * ...
  54      * s.setOption(SO_LINGER, new Integer(10));
  55      *    // OK - set SO_LINGER w/ timeout of 10 sec.
  56      * s.setOption(SO_LINGER, new Double(10));
  57      *    // ERROR - expects java.lang.Integer
  58      *</PRE>
  59      * If the requested option is binary, it can be set using this method by
  60      * a java.lang.Boolean:
  61      * <BR><PRE>
  62      * s.setOption(TCP_NODELAY, new Boolean(true));
  63      *    // OK - enables TCP_NODELAY, a binary option
  64      * </PRE>
  65      * <BR>
  66      * Any option can be disabled using this method with a Boolean(false):
  67      * <BR><PRE>
  68      * s.setOption(TCP_NODELAY, new Boolean(false));
  69      *    // OK - disables TCP_NODELAY
  70      * s.setOption(SO_LINGER, new Boolean(false));
  71      *    // OK - disables SO_LINGER
  72      * </PRE>
  73      * <BR>
  74      * For an option that has a notion of on and off, and requires
  75      * a non-boolean parameter, setting its value to anything other than
  76      * <I>Boolean(false)</I> implicitly enables it.
  77      * <BR>
  78      * Throws SocketException if the option is unrecognized,
  79      * the socket is closed, or some low-level error occurred
  80      * <BR>
  81      * @param optID identifies the option
  82      * @param value the parameter of the socket option
  83      * @throws SocketException if the option is unrecognized,
  84      * the socket is closed, or some low-level error occurred
  85      * @see #getOption(int)
  86      */
  87     public void
  88         setOption(int optID, Object value) throws SocketException;
  89 
  90     /**
  91      * Fetch the value of an option.
  92      * Binary options will return java.lang.Boolean(true)
  93      * if enabled, java.lang.Boolean(false) if disabled, e.g.:
  94      * <BR><PRE>
  95      * SocketImpl s;
  96      * ...
  97      * Boolean noDelay = (Boolean)(s.getOption(TCP_NODELAY));
  98      * if (noDelay.booleanValue()) {
  99      *     // true if TCP_NODELAY is enabled...
 100      * ...
 101      * }
 102      * </PRE>
 103      * <P>
 104      * For options that take a particular type as a parameter,
 105      * getOption(int) will return the parameter's value, else
 106      * it will return java.lang.Boolean(false):
 107      * <PRE>
 108      * Object o = s.getOption(SO_LINGER);
 109      * if (o instanceof Integer) {
 110      *     System.out.print("Linger time is " + ((Integer)o).intValue());
 111      * } else {
 112      *   // the true type of o is java.lang.Boolean(false);
 113      * }
 114      * </PRE>
 115      *
 116      * @param optID an <code>int</code> identifying the option to fetch
 117      * @return the value of the option
 118      * @throws SocketException if the socket is closed
 119      * @throws SocketException if <I>optID</I> is unknown along the
 120      *         protocol stack (including the SocketImpl)
 121      * @see #setOption(int, java.lang.Object)
 122      */
 123     public Object getOption(int optID) throws SocketException;
 124 
 125     /**
 126      * The java-supported BSD-style options.
 127      */
 128 
 129     /**
 130      * Disable Nagle's algorithm for this connection.  Written data
 131      * to the network is not buffered pending acknowledgement of
 132      * previously written data.
 133      *<P>
 134      * Valid for TCP only: SocketImpl.
 135      * <P>
 136      * @see Socket#setTcpNoDelay
 137      * @see Socket#getTcpNoDelay
 138      */
 139 
 140     public final static int TCP_NODELAY = 0x0001;
 141 
 142     /**
 143      * Fetch the local address binding of a socket (this option cannot
 144      * be "set" only "gotten", since sockets are bound at creation time,
 145      * and so the locally bound address cannot be changed).  The default local
 146      * address of a socket is INADDR_ANY, meaning any local address on a
 147      * multi-homed host.  A multi-homed host can use this option to accept
 148      * connections to only one of its addresses (in the case of a
 149      * ServerSocket or DatagramSocket), or to specify its return address
 150      * to the peer (for a Socket or DatagramSocket).  The parameter of
 151      * this option is an InetAddress.
 152      * <P>
 153      * This option <B>must</B> be specified in the constructor.
 154      * <P>
 155      * Valid for: SocketImpl, DatagramSocketImpl
 156      * <P>
 157      * @see Socket#getLocalAddress
 158      * @see DatagramSocket#getLocalAddress
 159      */
 160 
 161     public final static int SO_BINDADDR = 0x000F;
 162 
 163     /** Sets SO_REUSEADDR for a socket.  This is used only for MulticastSockets
 164      * in java, and it is set by default for MulticastSockets.
 165      * <P>
 166      * Valid for: DatagramSocketImpl
 167      */
 168 
 169     public final static int SO_REUSEADDR = 0x04;
 170 
 171     /**
 172      * Sets SO_BROADCAST for a socket. This option enables and disables
 173      * the ability of the process to send broadcast messages. It is supported
 174      * for only datagram sockets and only on networks that support
 175      * the concept of a broadcast message (e.g. Ethernet, token ring, etc.),
 176      * and it is set by default for DatagramSockets.
 177      * @since 1.4
 178      */
 179 
 180     public final static int SO_BROADCAST = 0x0020;
 181 
 182     /** Set which outgoing interface on which to send multicast packets.
 183      * Useful on hosts with multiple network interfaces, where applications
 184      * want to use other than the system default.  Takes/returns an InetAddress.
 185      * <P>
 186      * Valid for Multicast: DatagramSocketImpl
 187      * <P>
 188      * @see MulticastSocket#setInterface(InetAddress)
 189      * @see MulticastSocket#getInterface()
 190      */
 191 
 192     public final static int IP_MULTICAST_IF = 0x10;
 193 
 194     /** Same as above. This option is introduced so that the behaviour
 195      *  with IP_MULTICAST_IF will be kept the same as before, while
 196      *  this new option can support setting outgoing interfaces with either
 197      *  IPv4 and IPv6 addresses.
 198      *
 199      *  NOTE: make sure there is no conflict with this
 200      * @see MulticastSocket#setNetworkInterface(NetworkInterface)
 201      * @see MulticastSocket#getNetworkInterface()
 202      * @since 1.4
 203      */
 204     public final static int IP_MULTICAST_IF2 = 0x1f;
 205 
 206     /**
 207      * This option enables or disables local loopback of multicast datagrams.
 208      * This option is enabled by default for Multicast Sockets.
 209      * @since 1.4
 210      */
 211 
 212     public final static int IP_MULTICAST_LOOP = 0x12;
 213 
 214     /**
 215      * This option sets the type-of-service or traffic class field
 216      * in the IP header for a TCP or UDP socket.
 217      * @since 1.4
 218      */
 219 
 220     public final static int IP_TOS = 0x3;
 221 
 222     /**
 223      * Specify a linger-on-close timeout.  This option disables/enables
 224      * immediate return from a <B>close()</B> of a TCP Socket.  Enabling
 225      * this option with a non-zero Integer <I>timeout</I> means that a
 226      * <B>close()</B> will block pending the transmission and acknowledgement
 227      * of all data written to the peer, at which point the socket is closed
 228      * <I>gracefully</I>.  Upon reaching the linger timeout, the socket is
 229      * closed <I>forcefully</I>, with a TCP RST. Enabling the option with a
 230      * timeout of zero does a forceful close immediately. If the specified
 231      * timeout value exceeds 65,535 it will be reduced to 65,535.
 232      * <P>
 233      * Valid only for TCP: SocketImpl
 234      *
 235      * @see Socket#setSoLinger
 236      * @see Socket#getSoLinger
 237      */
 238     public final static int SO_LINGER = 0x0080;
 239 
 240     /** Set a timeout on blocking Socket operations:
 241      * <PRE>
 242      * ServerSocket.accept();
 243      * SocketInputStream.read();
 244      * DatagramSocket.receive();
 245      * </PRE>
 246      *
 247      * <P> The option must be set prior to entering a blocking
 248      * operation to take effect.  If the timeout expires and the
 249      * operation would continue to block,
 250      * <B>java.io.InterruptedIOException</B> is raised.  The Socket is
 251      * not closed in this case.
 252      *
 253      * <P> Valid for all sockets: SocketImpl, DatagramSocketImpl
 254      *
 255      * @see Socket#setSoTimeout
 256      * @see ServerSocket#setSoTimeout
 257      * @see DatagramSocket#setSoTimeout
 258      */
 259     public final static int SO_TIMEOUT = 0x1006;
 260 
 261     /**
 262      * Set a hint the size of the underlying buffers used by the
 263      * platform for outgoing network I/O. When used in set, this is a
 264      * suggestion to the kernel from the application about the size of
 265      * buffers to use for the data to be sent over the socket. When
 266      * used in get, this must return the size of the buffer actually
 267      * used by the platform when sending out data on this socket.
 268      *
 269      * Valid for all sockets: SocketImpl, DatagramSocketImpl
 270      *
 271      * @see Socket#setSendBufferSize
 272      * @see Socket#getSendBufferSize
 273      * @see DatagramSocket#setSendBufferSize
 274      * @see DatagramSocket#getSendBufferSize
 275      */
 276     public final static int SO_SNDBUF = 0x1001;
 277 
 278     /**
 279      * Set a hint the size of the underlying buffers used by the
 280      * platform for incoming network I/O. When used in set, this is a
 281      * suggestion to the kernel from the application about the size of
 282      * buffers to use for the data to be received over the
 283      * socket. When used in get, this must return the size of the
 284      * buffer actually used by the platform when receiving in data on
 285      * this socket.
 286      *
 287      * Valid for all sockets: SocketImpl, DatagramSocketImpl
 288      *
 289      * @see Socket#setReceiveBufferSize
 290      * @see Socket#getReceiveBufferSize
 291      * @see DatagramSocket#setReceiveBufferSize
 292      * @see DatagramSocket#getReceiveBufferSize
 293      */
 294     public final static int SO_RCVBUF = 0x1002;
 295 
 296     /**
 297      * When the keepalive option is set for a TCP socket and no data
 298      * has been exchanged across the socket in either direction for
 299      * 2 hours (NOTE: the actual value is implementation dependent),
 300      * TCP automatically sends a keepalive probe to the peer. This probe is a
 301      * TCP segment to which the peer must respond.
 302      * One of three responses is expected:
 303      * 1. The peer responds with the expected ACK. The application is not
 304      *    notified (since everything is OK). TCP will send another probe
 305      *    following another 2 hours of inactivity.
 306      * 2. The peer responds with an RST, which tells the local TCP that
 307      *    the peer host has crashed and rebooted. The socket is closed.
 308      * 3. There is no response from the peer. The socket is closed.
 309      *
 310      * The purpose of this option is to detect if the peer host crashes.
 311      *
 312      * Valid only for TCP socket: SocketImpl
 313      *
 314      * @see Socket#setKeepAlive
 315      * @see Socket#getKeepAlive
 316      */
 317     public final static int SO_KEEPALIVE = 0x0008;
 318 
 319     /**
 320      * When the OOBINLINE option is set, any TCP urgent data received on
 321      * the socket will be received through the socket input stream.
 322      * When the option is disabled (which is the default) urgent data
 323      * is silently discarded.
 324      *
 325      * @see Socket#setOOBInline
 326      * @see Socket#getOOBInline
 327      */
 328     public final static int SO_OOBINLINE = 0x1003;
 329 }