/*

 * Copyright (c) 2014, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package javax.security.auth.kerberos;

import javax.security.auth.Destroyable;

import java.util.Arrays;

import java.util.Base64;

import java.util.Objects;

/**

 * This class encapsulates a Kerberos 5 KRB_CRED message which can be used to

 * send Kerberos credentials from one principal to another.<p>

 *

 * A KRB_CRED message is defined in Section 5.8.1 of the Kerberos Protocol

 * Specification (<a href=http://www.ietf.org/rfc/rfc4120.txt>RFC 4120</a>) as:

 * <pre>

 *    KRB-CRED        ::= [APPLICATION 22] SEQUENCE {

 *            pvno            [0] INTEGER (5),

 *            msg-type        [1] INTEGER (22),

 *            tickets         [2] SEQUENCE OF Ticket,

 *            enc-part        [3] EncryptedData -- EncKrbCredPart

 *    }

 * </pre><p>

 *

 * @since 1.9

 */

public final class KerberosCredMessage implements Destroyable {

    final private KerberosPrincipal sender;

    final private KerberosPrincipal recipient;

    final private byte[] message;

    private boolean destroyed = false;

    /**

     * Constructs a {@code KerberosCredMessage} object.

     * <p>

     * The contents of the {@code message} argument are copied; subsequent

     * modification of the byte array does not affect the newly created object.

     *

     * @param sender the sender of the message

     * @param recipient the recipient of the message

     * @param message the DER encoded KRB_CRED message

     * @throws NullPointerException if any of sender, recipient

     *                              or message is null

     */

    public KerberosCredMessage(KerberosPrincipal sender,

                               KerberosPrincipal recipient,

                               byte[] message) {

        this.sender = Objects.requireNonNull(sender);

        this.recipient = Objects.requireNonNull(recipient);

        this.message = Objects.requireNonNull(message).clone();

    }

    /**

     * Returns the DER encoded form of the KRB_CRED message.

     *

     * @return a newly allocated byte array that contains the encoded form

     * @throws IllegalStateException if the object is destroyed

     */

    public byte[] getEncoded() {

        if (destroyed) {

            throw new IllegalStateException("This object is no longer valid");

        }

        return message.clone();

    }

    /**

     * Returns the sender of this message.

     *

     * @return the sender

     * @throws IllegalStateException if the object is destroyed

     */

    public KerberosPrincipal getSender() {

        if (destroyed) {

            throw new IllegalStateException("This object is no longer valid");

        }

        return sender;

    }

    /**

     * Returns the recipient of this message.

     *

     * @return the recipient

     * @throws IllegalStateException if the object is destroyed

     */

    public KerberosPrincipal getRecipient() {

        if (destroyed) {

            throw new IllegalStateException("This object is no longer valid");

        }

        return recipient;

    }

    /**

     * Destroys this object by clearing out the message.

     */

    @Override

    public void destroy() {

        if (!destroyed) {

            Arrays.fill(message, (byte)0);

            destroyed = true;

        }

    }

    @Override

    public boolean isDestroyed() {

        return destroyed;

    }

    @Override

    public String toString() {

        if (destroyed) {

            return "Destroyed KerberosCredMessage";

        } else {

            return "KRB_CRED from " + sender + " to " + recipient + ":\n"

                    + Base64.getUrlEncoder().encodeToString(message);

        }

    }

    @Override

    public int hashCode() {

        if (isDestroyed()) {

            return -1;

        } else {

            return Objects.hash(sender, recipient, Arrays.hashCode(message));

        }

    }

    @Override

    public boolean equals(Object other) {

        if (other == this) {

            return true;

        }

        if (! (other instanceof KerberosCredMessage)) {

            return false;

        }

        KerberosCredMessage otherMessage = ((KerberosCredMessage) other);

        if (isDestroyed() || otherMessage.isDestroyed()) {

            return false;

        }

        return Objects.equals(sender, otherMessage.sender)

                && Objects.equals(recipient, otherMessage.recipient)

                && Arrays.equals(message, otherMessage.message);

    }

}