/*

 * Copyright 1997-2006 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.x509;

import java.io.IOException;

import java.io.OutputStream;

import java.security.cert.CertificateException;

import java.util.Enumeration;

import java.util.Vector;

import sun.security.util.*;

/**

 * This class defines the certificate extension which specifies the

 * Policy constraints.

 * <p>

 * The policy constraints extension can be used in certificates issued

 * to CAs. The policy constraints extension constrains path validation

 * in two ways. It can be used to prohibit policy mapping or require

 * that each certificate in a path contain an acceptable policy

 * identifier.<p>

 * The ASN.1 syntax for this is (IMPLICIT tagging is defined in the

 * module definition):

 * <pre>

 * PolicyConstraints ::= SEQUENCE {

 *     requireExplicitPolicy [0] SkipCerts OPTIONAL,

 *     inhibitPolicyMapping  [1] SkipCerts OPTIONAL

 * }

 * SkipCerts ::= INTEGER (0..MAX)

 * </pre>

 * @author Amit Kapoor

 * @author Hemma Prafullchandra

 * @see Extension

 * @see CertAttrSet

 */

public class PolicyConstraintsExtension extends Extension

implements CertAttrSet<String> {

    /**

     * Identifier for this attribute, to be used with the

     * get, set, delete methods of Certificate, x509 type.

     */

    public static final String IDENT = "x509.info.extensions.PolicyConstraints";

    /**

     * Attribute names.

     */

    public static final String NAME = "PolicyConstraints";

    public static final String REQUIRE = "require";

    public static final String INHIBIT = "inhibit";

    private static final byte TAG_REQUIRE = 0;

    private static final byte TAG_INHIBIT = 1;

    private int require = -1;

    private int inhibit = -1;

    // Encode this extension value.

    private void encodeThis() throws IOException {

        if (require == -1 && inhibit == -1) {

            this.extensionValue = null;

            return;

        }

        DerOutputStream tagged = new DerOutputStream();

        DerOutputStream seq = new DerOutputStream();

        if (require != -1) {

            DerOutputStream tmp = new DerOutputStream();

            tmp.putInteger(require);

            tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,

                         false, TAG_REQUIRE), tmp);

        }

        if (inhibit != -1) {

            DerOutputStream tmp = new DerOutputStream();

            tmp.putInteger(inhibit);

            tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,

                         false, TAG_INHIBIT), tmp);

        }

        seq.write(DerValue.tag_Sequence, tagged);

        this.extensionValue = seq.toByteArray();

    }

    /**

     * Create a PolicyConstraintsExtension object with both

     * require explicit policy and inhibit policy mapping. The

     * extension is marked non-critical.

     *

     * @param require require explicit policy (-1 for optional).

     * @param inhibit inhibit policy mapping (-1 for optional).

     */

    public PolicyConstraintsExtension(int require, int inhibit)

    throws IOException {

        this(Boolean.FALSE, require, inhibit);

    }

    /**

     * Create a PolicyConstraintsExtension object with specified

     * criticality and both require explicit policy and inhibit

     * policy mapping.

     *

     * @param critical true if the extension is to be treated as critical.

     * @param require require explicit policy (-1 for optional).

     * @param inhibit inhibit policy mapping (-1 for optional).

     */

    public PolicyConstraintsExtension(Boolean critical, int require, int inhibit)

    throws IOException {

        this.require = require;

        this.inhibit = inhibit;

        this.extensionId = PKIXExtensions.PolicyConstraints_Id;

        this.critical = critical.booleanValue();

        encodeThis();

    }

    /**

     * Create the extension from its DER encoded value and criticality.

     *

     * @param critical true if the extension is to be treated as critical.

     * @param value an array of DER encoded bytes of the actual value.

     * @exception ClassCastException if value is not an array of bytes

     * @exception IOException on error.

     */

    public PolicyConstraintsExtension(Boolean critical, Object value)

    throws IOException {

        this.extensionId = PKIXExtensions.PolicyConstraints_Id;

        this.critical = critical.booleanValue();

        this.extensionValue = (byte[]) value;

        DerValue val = new DerValue(this.extensionValue);

        if (val.tag != DerValue.tag_Sequence) {

            throw new IOException("Sequence tag missing for PolicyConstraint.");

        }

        DerInputStream in = val.data;

        while (in != null && in.available() != 0) {

            DerValue next = in.getDerValue();

            if (next.isContextSpecific(TAG_REQUIRE) && !next.isConstructed()) {

                if (this.require != -1)

                    throw new IOException("Duplicate requireExplicitPolicy" +

                          "found in the PolicyConstraintsExtension");

                next.resetTag(DerValue.tag_Integer);

                this.require = next.getInteger();

            } else if (next.isContextSpecific(TAG_INHIBIT) &&

                       !next.isConstructed()) {

                if (this.inhibit != -1)

                    throw new IOException("Duplicate inhibitPolicyMapping" +

                          "found in the PolicyConstraintsExtension");

                next.resetTag(DerValue.tag_Integer);

                this.inhibit = next.getInteger();

            } else

                throw new IOException("Invalid encoding of PolicyConstraint");

        }

    }

    /**

     * Return the extension as user readable string.

     */

    public String toString() {

        String s;

        s = super.toString() + "PolicyConstraints: [" + "  Require: ";

        if (require == -1)

            s += "unspecified;";

        else

            s += require + ";";

        s += "\tInhibit: ";

        if (inhibit == -1)

            s += "unspecified";

        else

            s += inhibit;

        s += " ]\n";

        return s;

    }

    /**

     * Write the extension to the DerOutputStream.

     *

     * @param out the DerOutputStream to write the extension to.

     * @exception IOException on encoding errors.

     */

    public void encode(OutputStream out) throws IOException {

        DerOutputStream tmp = new DerOutputStream();

        if (extensionValue == null) {

          extensionId = PKIXExtensions.PolicyConstraints_Id;

          critical = false;

          encodeThis();

        }

        super.encode(tmp);

        out.write(tmp.toByteArray());

    }

    /**

     * Set the attribute value.

     */

    public void set(String name, Object obj) throws IOException {

        if (!(obj instanceof Integer)) {

            throw new IOException("Attribute value should be of type Integer.");

        }

        if (name.equalsIgnoreCase(REQUIRE)) {

            require = ((Integer)obj).intValue();

        } else if (name.equalsIgnoreCase(INHIBIT)) {

            inhibit = ((Integer)obj).intValue();

        } else {

          throw new IOException("Attribute name " + "[" + name + "]" +

                                " not recognized by " +

                                "CertAttrSet:PolicyConstraints.");

        }

        encodeThis();

    }

    /**

     * Get the attribute value.

     */

    public Object get(String name) throws IOException {

        if (name.equalsIgnoreCase(REQUIRE)) {

            return new Integer(require);

        } else if (name.equalsIgnoreCase(INHIBIT)) {

            return new Integer(inhibit);

        } else {

          throw new IOException("Attribute name not recognized by " +

                                "CertAttrSet:PolicyConstraints.");

        }

    }

    /**

     * Delete the attribute value.

     */

    public void delete(String name) throws IOException {

        if (name.equalsIgnoreCase(REQUIRE)) {

            require = -1;

        } else if (name.equalsIgnoreCase(INHIBIT)) {

            inhibit = -1;

        } else {

          throw new IOException("Attribute name not recognized by " +

                                "CertAttrSet:PolicyConstraints.");

        }

        encodeThis();

    }

    /**

     * Return an enumeration of names of attributes existing within this

     * attribute.

     */

    public Enumeration<String> getElements() {

        AttributeNameEnumeration elements = new AttributeNameEnumeration();

        elements.addElement(REQUIRE);

        elements.addElement(INHIBIT);

        return (elements.elements());

    }

    /**

     * Return the name of this attribute.

     */

    public String getName() {

        return (NAME);

    }

}