/*

 * 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.util.Arrays;

import sun.security.util.*;

/**

 * Represent a X509 Extension Attribute.

 *

 * <p>Extensions are additional attributes which can be inserted in a X509

 * v3 certificate. For example a "Driving License Certificate" could have

 * the driving license number as a extension.

 *

 * <p>Extensions are represented as a sequence of the extension identifier

 * (Object Identifier), a boolean flag stating whether the extension is to

 * be treated as being critical and the extension value itself (this is again

 * a DER encoding of the extension value).

 * <pre>

 * ASN.1 definition of Extension:

 * Extension ::= SEQUENCE {

 *      ExtensionId     OBJECT IDENTIFIER,

 *      critical        BOOLEAN DEFAULT FALSE,

 *      extensionValue  OCTET STRING

 * }

 * </pre>

 * All subclasses need to implement a constructor of the form

 * <pre>

 *     <subclass> (Boolean, Object)

 * </pre>

 * where the Object is typically an array of DER encoded bytes.

 * <p>

 * @author Amit Kapoor

 * @author Hemma Prafullchandra

 */

public class Extension implements java.security.cert.Extension {

    protected ObjectIdentifier  extensionId = null;

    protected boolean           critical = false;

    protected byte[]            extensionValue = null;

    /**

     * Default constructor.  Used only by sub-classes.

     */

    public Extension() { }

    /**

     * Constructs an extension from a DER encoded array of bytes.

     */

    public Extension(DerValue derVal) throws IOException {

        DerInputStream in = derVal.toDerInputStream();

        // Object identifier

        extensionId = in.getOID();

        // If the criticality flag was false, it will not have been encoded.

        DerValue val = in.getDerValue();

        if (val.tag == DerValue.tag_Boolean) {

            critical = val.getBoolean();

            // Extension value (DER encoded)

            val = in.getDerValue();

            extensionValue = val.getOctetString();

        } else {

            critical = false;

            extensionValue = val.getOctetString();

        }

    }

    /**

     * Constructs an Extension from individual components of ObjectIdentifier,

     * criticality and the DER encoded OctetString.

     *

     * @param extensionId the ObjectIdentifier of the extension

     * @param critical the boolean indicating if the extension is critical

     * @param extensionValue the DER encoded octet string of the value.

     */

    public Extension(ObjectIdentifier extensionId, boolean critical,

                     byte[] extensionValue) throws IOException {

        this.extensionId = extensionId;

        this.critical = critical;

        // passed in a DER encoded octet string, strip off the tag

        // and length

        DerValue inDerVal = new DerValue(extensionValue);

        this.extensionValue = inDerVal.getOctetString();

    }

    /**

     * Constructs an Extension from another extension. To be used for

     * creating decoded subclasses.

     *

     * @param ext the extension to create from.

     */

    public Extension(Extension ext) {

        this.extensionId = ext.extensionId;

        this.critical = ext.critical;

        this.extensionValue = ext.extensionValue;

    }

    /**

     * Constructs an Extension from individual components of ObjectIdentifier,

     * criticality and the raw encoded extension value.

     *

     * @param extensionId the ObjectIdentifier of the extension

     * @param critical the boolean indicating if the extension is critical

     * @param rawExtensionValue the raw DER-encoded extension value (this

     * is not the encoded OctetString).

     */

    public static Extension newExtension(ObjectIdentifier extensionId,

        boolean critical, byte[] rawExtensionValue) throws IOException {

        Extension ext = new Extension();

        ext.extensionId = extensionId;

        ext.critical = critical;

        ext.extensionValue = rawExtensionValue;

        return ext;

    }

    public void encode(OutputStream out) throws IOException {

        if (out == null) {

            throw new NullPointerException();

        }

        DerOutputStream dos1 = new DerOutputStream();

        DerOutputStream dos2 = new DerOutputStream();

        dos1.putOID(extensionId);

        if (critical) {

            dos1.putBoolean(critical);

        }

        dos1.putOctetString(extensionValue);

        dos2.write(DerValue.tag_Sequence, dos1);

        out.write(dos2.toByteArray());

    }

    /**

     * Write the extension to the DerOutputStream.

     *

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

     * @exception IOException on encoding errors

     */

    public void encode(DerOutputStream out) throws IOException {

        if (extensionId == null)

            throw new IOException("Null OID to encode for the extension!");

        if (extensionValue == null)

            throw new IOException("No value to encode for the extension!");

        DerOutputStream dos = new DerOutputStream();

        dos.putOID(extensionId);

        if (critical)

            dos.putBoolean(critical);

        dos.putOctetString(extensionValue);

        out.write(DerValue.tag_Sequence, dos);

    }

    /**

     * Returns true if extension is critical.

     */

    public boolean isCritical() {

        return critical;

    }

    /**

     * Returns the ObjectIdentifier of the extension.

     */

    public ObjectIdentifier getExtensionId() {

        return extensionId;

    }

    public byte[] getValue() {

        return extensionValue.clone();

    }

    /**

     * Returns the extension value as an byte array for further processing.

     * Note, this is the raw DER value of the extension, not the DER

     * encoded octet string which is in the certificate.

     * This method does not return a clone; it is the responsibility of the

     * caller to clone the array if necessary.

     */

    public byte[] getExtensionValue() {

        return extensionValue;

    }

    public String getId() {

        return extensionId.toString();

    }

    /**

     * Returns the Extension in user readable form.

     */

    public String toString() {

        String s = "ObjectId: " + extensionId.toString();

        if (critical) {

            s += " Criticality=true\n";

        } else {

            s += " Criticality=false\n";

        }

        return (s);

    }

    // Value to mix up the hash

    private static final int hashMagic = 31;

    /**

     * Returns a hashcode value for this Extension.

     *

     * @return the hashcode value.

     */

    public int hashCode() {

        int h = 0;

        if (extensionValue != null) {

            byte[] val = extensionValue;

            int len = val.length;

            while (len > 0)

                h += len * val[--len];

        }

        h = h * hashMagic + extensionId.hashCode();

        h = h * hashMagic + (critical?1231:1237);

        return h;

    }

    /**

     * Compares this Extension for equality with the specified

     * object. If the <code>other</code> object is an

     * <code>instanceof</code> <code>Extension</code>, then

     * its encoded form is retrieved and compared with the

     * encoded form of this Extension.

     *

     * @param other the object to test for equality with this Extension.

     * @return true iff the other object is of type Extension, and the

     * criticality flag, object identifier and encoded extension value of

     * the two Extensions match, false otherwise.

     */

    public boolean equals(Object other) {

        if (this == other)

            return true;

        if (!(other instanceof Extension))

            return false;

        Extension otherExt = (Extension) other;

        if (critical != otherExt.critical)

            return false;

        if (!extensionId.equals(otherExt.extensionId))

            return false;

        return Arrays.equals(extensionValue, otherExt.extensionValue);

    }

}