/*

 * Copyright (c) 2003, 2005, 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 com.sun.jmx.remote.security;

import java.security.AccessControlContext;

import java.security.AccessController;

import java.security.CodeSource;

import java.security.Permissions;

import java.security.ProtectionDomain;

import javax.security.auth.Subject;

import javax.security.auth.SubjectDomainCombiner;

/**

 * <p>This class represents an extension to the {@link SubjectDomainCombiner}

 * and is used to add a new {@link ProtectionDomain}, comprised of a null

 * codesource/signers and an empty permission set, to the access control

 * context with which this combiner is combined.</p>

 *

 * <p>When the {@link #combine} method is called the {@link ProtectionDomain}

 * is augmented with the permissions granted to the set of principals present

 * in the supplied {@link Subject}.</p>

 */

public class JMXSubjectDomainCombiner extends SubjectDomainCombiner {

    public JMXSubjectDomainCombiner(Subject s) {

        super(s);

    }

    public ProtectionDomain[] combine(ProtectionDomain[] current,

                                      ProtectionDomain[] assigned) {

        // Add a new ProtectionDomain with the null codesource/signers, and

        // the empty permission set, to the end of the array containing the

        // 'current' protections domains, i.e. the ones that will be augmented

        // with the permissions granted to the set of principals present in

        // the supplied subject.

        //

        ProtectionDomain[] newCurrent;

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

            newCurrent = new ProtectionDomain[1];

            newCurrent[0] = pdNoPerms;

        } else {

            newCurrent = new ProtectionDomain[current.length + 1];

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

                newCurrent[i] = current[i];

            }

            newCurrent[current.length] = pdNoPerms;

        }

        return super.combine(newCurrent, assigned);

    }

    /**

     * A null CodeSource.

     */

    private static final CodeSource nullCodeSource =

        new CodeSource(null, (java.security.cert.Certificate[]) null);

    /**

     * A ProtectionDomain with a null CodeSource and an empty permission set.

     */

    private static final ProtectionDomain pdNoPerms =

        new ProtectionDomain(nullCodeSource, new Permissions(), null, null);

    /**

     * Get the current AccessControlContext combined with the supplied subject.

     */

    public static AccessControlContext getContext(Subject subject) {

        return new AccessControlContext(AccessController.getContext(),

                                        new JMXSubjectDomainCombiner(subject));

    }

    /**

     * Get the AccessControlContext of the domain combiner created with

     * the supplied subject, i.e. an AccessControlContext with the domain

     * combiner created with the supplied subject and where the caller's

     * context has been removed.

     */

    public static AccessControlContext

        getDomainCombinerContext(Subject subject) {

        return new AccessControlContext(

            new AccessControlContext(new ProtectionDomain[0]),

            new JMXSubjectDomainCombiner(subject));

    }

}