1 /*

     2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.

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

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     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.

    10  *

    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).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package sun.net.ext;

    27 

    28 import java.io.FileDescriptor;

    29 import java.net.SocketException;

    30 import java.net.SocketOption;

    31 import java.util.Collections;

    32 import java.util.Set;

    33 

    34 /**

    35  * Defines the infrastructure to support extended socket options, beyond those

    36  * defined in {@link java.net.StandardSocketOptions}.

    37  *

    38  * Extended socket options are accessed through the jdk.net API, which is in

    39  * the jdk.net module.

    40  */

    41 public abstract class ExtendedSocketOptions {

    42 

    43     private final Set<SocketOption<?>> options;

    44 

    45     /** Tells whether or not the option is supported. */

    46     public final boolean isOptionSupported(SocketOption<?> option) {

    47         return options().contains(option);

    48     }

    49 

    50     /** Return the, possibly empty, set of extended socket options available. */

    51     public final Set<SocketOption<?>> options() { return options; }

    52 

    53     /** Sets the value of a socket option, for the given socket. */

    54     public abstract void setOption(FileDescriptor fd, SocketOption<?> option, Object value)

    55             throws SocketException;

    56 

    57     /** Returns the value of a socket option, for the given socket. */

    58     public abstract Object getOption(FileDescriptor fd, SocketOption<?> option)

    59             throws SocketException;

    60 

    61     protected ExtendedSocketOptions(Set<SocketOption<?>> options) {

    62         this.options = options;

    63     }

    64 

    65     private static volatile ExtendedSocketOptions instance;

    66 

    67     public static final ExtendedSocketOptions getInstance() { return instance; }

    68 

    69     /** Registers support for extended socket options. Invoked by the jdk.net module. */

    70     public static final void register(ExtendedSocketOptions extOptions) {

    71         if (instance != null)

    72             throw new InternalError("Attempting to reregister extended options");

    73 

    74         instance = extOptions;

    75     }

    76 

    77     static {

    78         try {

    79             // If the class is present, it will be initialized which

    80             // triggers registration of the extended socket options.

    81             Class<?> c = Class.forName("jdk.net.ExtendedSocketOptions");

    82         } catch (ClassNotFoundException e) {

    83             // the jdk.net module is not present => no extended socket options

    84             instance = new NoExtendedSocketOptions();

    85         }

    86     }

    87 

    88     static final class NoExtendedSocketOptions extends ExtendedSocketOptions {

    89 

    90         NoExtendedSocketOptions() {

    91             super(Collections.<SocketOption<?>>emptySet());

    92         }

    93 

    94         @Override

    95         public void setOption(FileDescriptor fd, SocketOption<?> option, Object value)

    96             throws SocketException

    97         {

    98             throw new UnsupportedOperationException(

    99                     "no extended options: " + option.name());

   100         }

   101 

   102         @Override

   103         public Object getOption(FileDescriptor fd, SocketOption<?> option)

   104             throws SocketException

   105         {

   106             throw new UnsupportedOperationException(

   107                     "no extended options: " + option.name());

   108         }

   109     }

   110 }