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 * Copyright (c) 2020, 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.

 *

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package com.sun.naming.internal;

import javax.naming.Reference;

import sun.misc.ObjectInputFilter;

import sun.misc.ObjectInputFilter.FilterInfo;

import sun.misc.ObjectInputFilter.Status;

import sun.security.util.SecurityProperties;

/**

 * This class implements the filter that validates object factories classes instantiated

 * during {@link Reference} lookups.

 * There is one system-wide filter instance per VM that can be set via

 * the {@code "jdk.jndi.object.factoriesFilter"} system property value, or via

 * setting the property in the security properties file. The system property value supersedes

 * the security property value. If none of the properties are specified the default

 * "*" value is used.

 * The filter is implemented as {@link ObjectInputFilter} with capabilities limited to the

 * validation of a factory's class types only ({@linkplain FilterInfo#serialClass()}).

 * Array length, number of object references, depth, and stream size filtering capabilities are

 * not supported by the filter.

 */

public final class ObjectFactoriesFilter {

    /**

     * Checks if serial filter configured with {@code "jdk.jndi.object.factoriesFilter"}

     * system property value allows instantiation of the specified objects factory class.

     * If the filter result is not {@linkplain Status#REJECTED REJECTED}, the filter will

     * allow the instantiation of objects factory class.

     *

     * @param factoryClass objects factory class

     * @return true - if the factory is allowed to be instantiated; false - otherwise

     */

    public static boolean canInstantiateObjectsFactory(Class<?> factoryClass) {

        return checkInput(() -> factoryClass);

    }

    private static boolean checkInput(FactoryInfo factoryInfo) {

        Status result = GLOBAL.checkInput(factoryInfo);

        return result != Status.REJECTED;

    }

    // FilterInfo to check if objects factory class is allowed by the system-wide

    // filter. Array length, number of object references, depth, and stream size

    // capabilities are ignored.

    @FunctionalInterface

    private interface FactoryInfo extends FilterInfo {

        @Override

        default long arrayLength() {

            return -1;

        }

        @Override

        default long depth() {

            return 1;

        }

        @Override

        default long references() {

            return 0;

        }

        @Override

        default long streamBytes() {

            return 0;

        }

    }

    // Prevent instantiation of the factories filter class

     private ObjectFactoriesFilter() {

         throw new InternalError("Not instantiable");

     }

    // System property name that contains the patterns to filter object factory names

    private static final String FACTORIES_FILTER_PROPNAME = "jdk.jndi.object.factoriesFilter";

    // Default system property value that allows the load of any object factory classes

    private static final String DEFAULT_SP_VALUE = "*";

    // System wide object factories filter constructed from the system property

    private static final ObjectInputFilter GLOBAL =

            ObjectInputFilter.Config.createFilter(getFilterPropertyValue());

    // Get security or system property value

    private static String getFilterPropertyValue() {

        String propVal = SecurityProperties.privilegedGetOverridable(FACTORIES_FILTER_PROPNAME);

        return propVal != null ? propVal : DEFAULT_SP_VALUE;

    }

}