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.unmodifiableSet(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("no extended options");
  99         }
 100 
 101         @Override
 102         public Object getOption(FileDescriptor fd, SocketOption<?> option)
 103             throws SocketException
 104         {
 105             throw new UnsupportedOperationException("no extended options");
 106         }
 107     }
 108 }