/*

 * Copyright (c) 2015, 2019, 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.security.util;

import java.security.AccessController;

import java.security.AlgorithmConstraints;

import java.security.PrivilegedAction;

import java.security.Security;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.List;

import java.util.Set;

/**

 * The class contains common functionality for algorithm constraints classes.

 */

public abstract class AbstractAlgorithmConstraints

        implements AlgorithmConstraints {

    protected final AlgorithmDecomposer decomposer;

    protected AbstractAlgorithmConstraints(AlgorithmDecomposer decomposer) {

        this.decomposer = decomposer;

    }

    // Get algorithm constraints from the specified security property.

    static List<String> getAlgorithms(String propertyName) {

        String property = AccessController.doPrivileged(

                new PrivilegedAction<String>() {

                    @Override

                    public String run() {

                        return Security.getProperty(propertyName);

                    }

                });

        String[] algorithmsInProperty = null;

        if (property != null && !property.isEmpty()) {

            // remove double quote marks from beginning/end of the property

            if (property.length() >= 2 && property.charAt(0) == '"' &&

                    property.charAt(property.length() - 1) == '"') {

                property = property.substring(1, property.length() - 1);

            }

            algorithmsInProperty = property.split(",");

            for (int i = 0; i < algorithmsInProperty.length; i++) {

                algorithmsInProperty[i] = algorithmsInProperty[i].trim();

            }

        }

        // map the disabled algorithms

        if (algorithmsInProperty == null) {

            return Collections.emptyList();

        }

        return new ArrayList<>(Arrays.asList(algorithmsInProperty));

    }

    static boolean checkAlgorithm(List<String> algorithms, String algorithm,

            AlgorithmDecomposer decomposer) {

        if (algorithm == null || algorithm.length() == 0) {

            throw new IllegalArgumentException("No algorithm name specified");

        }

        Set<String> elements = null;

        for (String item : algorithms) {

            if (item == null || item.isEmpty()) {

                continue;

            }

            // check the full name

            if (item.equalsIgnoreCase(algorithm)) {

                return false;

            }

            // decompose the algorithm into sub-elements

            if (elements == null) {

                elements = decomposer.decompose(algorithm);

            }

            // check the items of the algorithm

            for (String element : elements) {

                if (item.equalsIgnoreCase(element)) {

                    return false;

                }

            }

        }

        return true;

    }

}