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Copy pathDefaultDatagramSocketImplFactory.java
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142 lines (128 loc) · 4.72 KB
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/*
* Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*/
package java.net;
import java.security.AccessController;
import java.security.PrivilegedAction;
/**
* This class defines a factory for creating DatagramSocketImpls. It defaults
* to creating plain DatagramSocketImpls, but may create other DatagramSocketImpls
* by setting the impl.prefix system property.
*
* For Windows versions lower than Windows Vista a TwoStacksPlainDatagramSocketImpl
* is always created. This impl supports IPv6 on these platform where available.
*
* On Windows platforms greater than Vista that support a dual layer TCP/IP stack
* a DualStackPlainDatagramSocketImpl is created for DatagramSockets. For MulticastSockets
* a TwoStacksPlainDatagramSocketImpl is always created. This is to overcome the lack
* of behavior defined for multicasting over a dual layer socket by the RFC.
*
* @author Chris Hegarty
*/
class DefaultDatagramSocketImplFactory
{
private final static Class<?> prefixImplClass;
/* the windows version. */
private static float version;
/* java.net.preferIPv4Stack */
private static boolean preferIPv4Stack = false;
/* If the version supports a dual stack TCP implementation */
private final static boolean useDualStackImpl;
/* sun.net.useExclusiveBind */
private static String exclBindProp;
/* True if exclusive binding is on for Windows */
private final static boolean exclusiveBind;
static {
Class<?> prefixImplClassLocal = null;
boolean useDualStackImplLocal = false;
boolean exclusiveBindLocal = true;
// Determine Windows Version.
java.security.AccessController.doPrivileged(
new PrivilegedAction<Object>() {
public Object run() {
version = 0;
try {
version = Float.parseFloat(System.getProperties()
.getProperty("os.version"));
preferIPv4Stack = Boolean.parseBoolean(
System.getProperties()
.getProperty(
"java.net.preferIPv4Stack"));
exclBindProp = System.getProperty(
"sun.net.useExclusiveBind");
} catch (NumberFormatException e) {
assert false : e;
}
return null; // nothing to return
}
});
// (version >= 6.0) implies Vista or greater.
if (version >= 6.0 && !preferIPv4Stack) {
useDualStackImplLocal = true;
}
if (exclBindProp != null) {
// sun.net.useExclusiveBind is true
exclusiveBindLocal = exclBindProp.length() == 0 ? true
: Boolean.parseBoolean(exclBindProp);
} else if (version < 6.0) {
exclusiveBindLocal = false;
}
// impl.prefix
String prefix = null;
try {
prefix = AccessController.doPrivileged(
new sun.security.action.GetPropertyAction("impl.prefix", null));
if (prefix != null)
prefixImplClassLocal = Class.forName("java.net."+prefix+"DatagramSocketImpl");
} catch (Exception e) {
System.err.println("Can't find class: java.net." +
prefix +
"DatagramSocketImpl: check impl.prefix property");
}
prefixImplClass = prefixImplClassLocal;
useDualStackImpl = useDualStackImplLocal;
exclusiveBind = exclusiveBindLocal;
}
/**
* Creates a new <code>DatagramSocketImpl</code> instance.
*
* @param isMulticast true if this impl is to be used for a MutlicastSocket
* @return a new instance of <code>PlainDatagramSocketImpl</code>.
*/
static DatagramSocketImpl createDatagramSocketImpl(boolean isMulticast)
throws SocketException {
if (prefixImplClass != null) {
try {
return (DatagramSocketImpl) prefixImplClass.newInstance();
} catch (Exception e) {
throw new SocketException("can't instantiate DatagramSocketImpl");
}
} else {
if (useDualStackImpl && !isMulticast)
return new DualStackPlainDatagramSocketImpl(exclusiveBind);
else
return new TwoStacksPlainDatagramSocketImpl(exclusiveBind && !isMulticast);
}
}
}