/*

 * Copyright (c) 1998, 2010, 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

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

 * questions.

 */

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 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 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 = null;

        try {

            tmp = new Integer(

              java.security.AccessController.doPrivileged (

                new PrivilegedAction<String>() {

                  public String run() {

                      return Security.getProperty(cachePolicyProp);

                  }

              }));

        } catch (NumberFormatException e) {

            // ignore

        }

        if (tmp != null) {

            cachePolicy = tmp.intValue();

            if (cachePolicy < 0) {

                cachePolicy = FOREVER;

            }

            propertySet = true;

        } else {

            tmp = java.security.AccessController.doPrivileged

                (new sun.security.action.GetIntegerAction(cachePolicyPropFallback));

            if (tmp != null) {

                cachePolicy = tmp.intValue();

                if (cachePolicy < 0) {

                    cachePolicy = FOREVER;

                }

                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;

                }

            }

        }

        try {

            tmp = new Integer(

              java.security.AccessController.doPrivileged (

                new PrivilegedAction<String>() {

                  public String run() {

                      return Security.getProperty(negativeCachePolicyProp);

                  }

              }));

        } catch (NumberFormatException e) {

            // ignore

        }

        if (tmp != null) {

            negativeCachePolicy = tmp.intValue();

            if (negativeCachePolicy < 0) {

                negativeCachePolicy = FOREVER;

            }

            propertyNegativeSet = true;

        } else {

            tmp = java.security.AccessController.doPrivileged

                (new sun.security.action.GetIntegerAction(negativeCachePolicyPropFallback));

            if (tmp != null) {

                negativeCachePolicy = tmp.intValue();

                if (negativeCachePolicy < 0) {

                    negativeCachePolicy = FOREVER;

                }

                propertyNegativeSet = true;

            }

        }

    }

    public static synchronized int get() {

        return cachePolicy;

    }

    public static synchronized 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 synchronized 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);

            negativeCachePolicy = 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");

        }

    }

}