/*
* Copyright (c) 1998, 2014, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package sun.net;
import java.security.PrivilegedAction;
import java.security.Security;
public final class InetAddressCachePolicy {
// Controls the cache policy for successful lookups only
private static final String cachePolicyProp = "networkaddress.cache.ttl";
private static final String cachePolicyPropFallback =
"sun.net.inetaddr.ttl";
// Controls the cache policy for negative lookups only
private static final String negativeCachePolicyProp =
"networkaddress.cache.negative.ttl";
private static final String negativeCachePolicyPropFallback =
"sun.net.inetaddr.negative.ttl";
public static final int FOREVER = -1;
public static final int NEVER = 0;
/* default value for positive lookups */
public static final int DEFAULT_POSITIVE = 30;
/* The Java-level namelookup cache policy for successful lookups:
*
* -1: caching forever
* any positive value: the number of seconds to cache an address for
*
* default value is forever (FOREVER), as we let the platform do the
* caching. For security reasons, this caching is made forever when
* a security manager is set.
*/
private static volatile int cachePolicy = FOREVER;
/* The Java-level namelookup cache policy for negative lookups:
*
* -1: caching forever
* any positive value: the number of seconds to cache an address for
*
* default value is 0. It can be set to some other value for
* performance reasons.
*/
private static volatile int negativeCachePolicy = NEVER;
/*
* Whether or not the cache policy for successful lookups was set
* using a property (cmd line).
*/
private static boolean propertySet;
/*
* Whether or not the cache policy for negative lookups was set
* using a property (cmd line).
*/
private static boolean propertyNegativeSet;
/*
* Initialize
*/
static {
Integer tmp = java.security.AccessController.doPrivileged(
new PrivilegedAction<Integer>() {
public Integer run() {
try {
String tmpString = Security.getProperty(cachePolicyProp);
if (tmpString != null) {
return Integer.valueOf(tmpString);
}
} catch (NumberFormatException ignored) {
// Ignore
}
try {
String tmpString = System.getProperty(cachePolicyPropFallback);
if (tmpString != null) {
return Integer.decode(tmpString);
}
} catch (NumberFormatException ignored) {
// Ignore
}
return null;
}
});
if (tmp != null) {
cachePolicy = tmp < 0 ? FOREVER : tmp;
propertySet = true;
} else {
/* No properties defined for positive caching. If there is no
* security manager then use the default positive cache value.
*/
if (System.getSecurityManager() == null) {
cachePolicy = DEFAULT_POSITIVE;
}
}
tmp = java.security.AccessController.doPrivileged (
new PrivilegedAction<Integer>() {
public Integer run() {
try {
String tmpString = Security.getProperty(negativeCachePolicyProp);
if (tmpString != null) {
return Integer.valueOf(tmpString);
}
} catch (NumberFormatException ignored) {
// Ignore
}
try {
String tmpString = System.getProperty(negativeCachePolicyPropFallback);
if (tmpString != null) {
return Integer.decode(tmpString);
}
} catch (NumberFormatException ignored) {
// Ignore
}
return null;
}
});
if (tmp != null) {
negativeCachePolicy = tmp < 0 ? FOREVER : tmp;
propertyNegativeSet = true;
}
}
public static int get() {
return cachePolicy;
}
public static int getNegative() {
return negativeCachePolicy;
}
/**
* Sets the cache policy for successful lookups if the user has not
* already specified a cache policy for it using a
* command-property.
* @param newPolicy the value in seconds for how long the lookup
* should be cached
*/
public static synchronized void setIfNotSet(int newPolicy) {
/*
* When setting the new value we may want to signal that the
* cache should be flushed, though this doesn't seem strictly
* necessary.
*/
if (!propertySet) {
checkValue(newPolicy, cachePolicy);
cachePolicy = newPolicy;
}
}
/**
* Sets the cache policy for negative lookups if the user has not
* already specified a cache policy for it using a
* command-property.
* @param newPolicy the value in seconds for how long the lookup
* should be cached
*/
public static void setNegativeIfNotSet(int newPolicy) {
/*
* When setting the new value we may want to signal that the
* cache should be flushed, though this doesn't seem strictly
* necessary.
*/
if (!propertyNegativeSet) {
// Negative caching does not seem to have any security
// implications.
// checkValue(newPolicy, negativeCachePolicy);
// but we should normalize negative policy
negativeCachePolicy = newPolicy < 0 ? FOREVER : newPolicy;
}
}
private static void checkValue(int newPolicy, int oldPolicy) {
/*
* If malicious code gets a hold of this method, prevent
* setting the cache policy to something laxer or some
* invalid negative value.
*/
if (newPolicy == FOREVER)
return;
if ((oldPolicy == FOREVER) ||
(newPolicy < oldPolicy) ||
(newPolicy < FOREVER)) {
throw new
SecurityException("can't make InetAddress cache more lax");
}
}
}