1 /*
2 * Copyright (c) 2007, 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 package java.net;
26
27 import java.security.AccessController;
28 import java.security.PrivilegedAction;
29
30 /**
31 * This class defines a factory for creating DatagramSocketImpls. It defaults
32 * to creating plain DatagramSocketImpls, but may create other DatagramSocketImpls
33 * by setting the impl.prefix system property.
34 *
35 * For Windows versions lower than Windows Vista a TwoStacksPlainDatagramSocketImpl
36 * is always created. This impl supports IPv6 on these platform where available.
37 *
38 * On Windows platforms greater than Vista that support a dual layer TCP/IP stack
39 * a DualStackPlainDatagramSocketImpl is created for DatagramSockets. For MulticastSockets
40 * a TwoStacksPlainDatagramSocketImpl is always created. This is to overcome the lack
41 * of behavior defined for multicasting over a dual layer socket by the RFC.
42 *
43 * @author Chris Hegarty
44 */
45
46 class DefaultDatagramSocketImplFactory
47 {
48 static Class prefixImplClass = null;
49
50 /* the windows version. */
51 private static float version;
52
53 /* java.net.preferIPv4Stack */
54 private static boolean preferIPv4Stack = false;
55
56 /* If the version supports a dual stack TCP implementation */
57 private static boolean useDualStackImpl = false;
58
59 /* sun.net.useExclusiveBind */
60 private static String exclBindProp;
61
62 /* True if exclusive binding is on for Windows */
63 private static boolean exclusiveBind = true;
64
65
66 static {
67 // Determine Windows Version.
68 java.security.AccessController.doPrivileged(
69 new PrivilegedAction<Object>() {
70 public Object run() {
71 version = 0;
72 try {
73 version = Float.parseFloat(System.getProperties()
74 .getProperty("os.version"));
75 preferIPv4Stack = Boolean.parseBoolean(
76 System.getProperties()
77 .getProperty(
78 "java.net.preferIPv4Stack"));
79 exclBindProp = System.getProperty(
80 "sun.net.useExclusiveBind");
81 } catch (NumberFormatException e ) {
82 assert false : e;
83 }
84 return null; // nothing to return
85 }
86 });
87
88 // (version >= 6.0) implies Vista or greater.
89 if (version >= 6.0 && !preferIPv4Stack) {
90 useDualStackImpl = true;
91 }
92 if (exclBindProp != null) {
93 // sun.net.useExclusiveBind is true
94 exclusiveBind = exclBindProp.length() == 0 ? true
95 : Boolean.parseBoolean(exclBindProp);
96 } else if (version < 6.0) {
97 exclusiveBind = false;
98 }
99
100 // impl.prefix
101 String prefix = null;
102 try {
103 prefix = AccessController.doPrivileged(
104 new sun.security.action.GetPropertyAction("impl.prefix", null));
105 if (prefix != null)
106 prefixImplClass = Class.forName("java.net."+prefix+"DatagramSocketImpl");
107 } catch (Exception e) {
108 System.err.println("Can't find class: java.net." +
109 prefix +
110 "DatagramSocketImpl: check impl.prefix property");
111 }
112 }
113
114 /**
115 * Creates a new <code>DatagramSocketImpl</code> instance.
116 *
117 * @param isMulticast true if this impl is to be used for a MutlicastSocket
118 * @return a new instance of <code>PlainDatagramSocketImpl</code>.
119 */
120 static DatagramSocketImpl createDatagramSocketImpl(boolean isMulticast)
121 throws SocketException {
122 if (prefixImplClass != null) {
123 try {
124 return (DatagramSocketImpl) prefixImplClass.newInstance();
125 } catch (Exception e) {
126 throw new SocketException("can't instantiate DatagramSocketImpl");
127 }
128 } else {
129 if (isMulticast)
130 exclusiveBind = false;
131 if (useDualStackImpl && !isMulticast)
132 return new DualStackPlainDatagramSocketImpl(exclusiveBind);
133 else
134 return new TwoStacksPlainDatagramSocketImpl(exclusiveBind);
135 }
136 }
137 }