/*

 * Copyright 2000-2003 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.security.provider.certpath;

import java.util.*;

import java.security.cert.*;

import sun.security.util.Debug;

import sun.security.x509.PKIXExtensions;

/**

 * KeyChecker is a <code>PKIXCertPathChecker</code> that checks that the

 * keyCertSign bit is set in the keyUsage extension in an intermediate CA

 * certificate. It also checks whether the final certificate in a

 * certification path meets the specified target constraints specified as

 * a CertSelector in the PKIXParameters passed to the CertPathValidator.

 *

 * @since       1.4

 * @author      Yassir Elley

 */

class KeyChecker extends PKIXCertPathChecker {

    private static final Debug debug = Debug.getInstance("certpath");

    // the index of keyCertSign in the boolean KeyUsage array

    private static final int keyCertSign = 5;

    private final int certPathLen;

    private CertSelector targetConstraints;

    private int remainingCerts;

    /**

     * Default Constructor

     *

     * @param certPathLen allowable cert path length

     * @param targetCertSel a CertSelector object specifying the constraints

     * on the target certificate

     */

    KeyChecker(int certPathLen, CertSelector targetCertSel)

        throws CertPathValidatorException

    {

        this.certPathLen = certPathLen;

        this.targetConstraints = targetCertSel;

        init(false);

    }

    /**

     * Initializes the internal state of the checker from parameters

     * specified in the constructor

     */

    public void init(boolean forward) throws CertPathValidatorException {

        if (!forward) {

            remainingCerts = certPathLen;

        } else {

            throw new CertPathValidatorException("forward checking not supported");

        }

    }

    public boolean isForwardCheckingSupported() {

        return false;

    }

    public Set<String> getSupportedExtensions() {

        if (supportedExts == null) {

            supportedExts = new HashSet<String>();

            supportedExts.add(PKIXExtensions.KeyUsage_Id.toString());

            supportedExts.add(PKIXExtensions.ExtendedKeyUsage_Id.toString());

            supportedExts.add(PKIXExtensions.SubjectAlternativeName_Id.toString());

            supportedExts = Collections.unmodifiableSet(supportedExts);

        }

        return supportedExts;

    }

    /**

     * Checks that keyUsage and target constraints are satisfied by

     * the specified certificate.

     *

     * @param cert the Certificate

     * @param unresolvedCritExts the unresolved critical extensions

     * @exception CertPathValidatorException Exception thrown if certificate

     * does not verify

     */

    public void check(Certificate cert, Collection<String> unresCritExts)

        throws CertPathValidatorException

    {

        X509Certificate currCert = (X509Certificate) cert;

        remainingCerts--;

        // if final certificate, check that target constraints are satisfied

        if (remainingCerts == 0) {

            if ((targetConstraints != null) &&

                (targetConstraints.match(currCert) == false)) {

                throw new CertPathValidatorException("target certificate " +

                    "constraints check failed");

            }

        } else {

            // otherwise, verify that keyCertSign bit is set in CA certificate

            verifyCAKeyUsage(currCert);

        }

        // remove the extensions that we have checked

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

            unresCritExts.remove(PKIXExtensions.KeyUsage_Id.toString());

            unresCritExts.remove(PKIXExtensions.ExtendedKeyUsage_Id.toString());

            unresCritExts.remove(

                PKIXExtensions.SubjectAlternativeName_Id.toString());

        }

    }

    /**

     * Static method to verify that the key usage and extended key usage

     * extension in a CA cert. The key usage extension, if present, must

     * assert the keyCertSign bit. The extended key usage extension, if

     * present, must include anyExtendedKeyUsage.

     */

    static void verifyCAKeyUsage(X509Certificate cert)

            throws CertPathValidatorException {

        String msg = "CA key usage";

        if (debug != null) {

            debug.println("KeyChecker.verifyCAKeyUsage() ---checking " + msg

                + "...");

        }

        boolean[] keyUsageBits = cert.getKeyUsage();

        // getKeyUsage returns null if the KeyUsage extension is not present

        // in the certificate - in which case there is nothing to check

        if (keyUsageBits == null) {

            return;

        }

        // throw an exception if the keyCertSign bit is not set

        if (!keyUsageBits[keyCertSign]) {

            throw new CertPathValidatorException(msg + " check failed: "

                + "keyCertSign bit is not set");

        }

        if (debug != null) {

            debug.println("KeyChecker.verifyCAKeyUsage() " + msg

                + " verified.");

        }

    }

}