/*

 * 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

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

 *

 * 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.

 *

 */

/*

 *

 *  (C) Copyright IBM Corp. 1999 All Rights Reserved.

 *  Copyright 1997 The Open Group Research Institute.  All rights reserved.

 */

package sun.security.krb5;

import sun.security.krb5.internal.*;

import sun.security.krb5.internal.crypto.KeyUsage;

import sun.security.util.*;

import java.io.IOException;

/**

 * This class encapsulates a KRB-AP-REP sent from the service to the

 * client.

 */

public class KrbApRep {

    private byte[] obuf;

    private byte[] ibuf;

    private EncAPRepPart encPart; // although in plain text

    private APRep apRepMessg;

    /**

     * Constructs a KRB-AP-REP to send to a client.

     * @throws KrbException

     * @throws IOException

     */

     // Used in AcceptSecContextToken

    public KrbApRep(KrbApReq incomingReq,

                    boolean useSeqNumber,

        boolean useSubKey) throws KrbException, IOException {

        EncryptionKey subKey =

            (useSubKey?

             new EncryptionKey(incomingReq.getCreds().getSessionKey()):null);

        SeqNumber seqNum = new LocalSeqNumber();

        init(incomingReq, subKey, seqNum);

    }

    /**

     * Constructs a KRB-AP-REQ from the bytes received from a service.

     * @throws KrbException

     * @throws IOException

     */

     // Used in AcceptSecContextToken

    public KrbApRep(byte[] message, Credentials tgtCreds,

                    KrbApReq outgoingReq) throws KrbException, IOException {

        this(message, tgtCreds);

        authenticate(outgoingReq);

    }

    private void init(KrbApReq apReq,

              EncryptionKey subKey,

        SeqNumber seqNumber)

        throws KrbException, IOException {

        createMessage(

                      apReq.getCreds().key,

                      apReq.getCtime(),

                      apReq.cusec(),

                      subKey,

                      seqNumber);

        obuf = apRepMessg.asn1Encode();

    }

    /**

     * Constructs a KrbApRep object.

     * @param msg a byte array of reply message.

     * @param tgs_creds client's credential.

     * @exception KrbException

     * @exception IOException

     */

    private KrbApRep(byte[] msg, Credentials tgs_creds)

        throws KrbException, IOException {

        this(new DerValue(msg), tgs_creds);

    }

    /**

     * Constructs a KrbApRep object.

     * @param msg a byte array of reply message.

     * @param tgs_creds client's credential.

     * @exception KrbException

     * @exception IOException

     */

    private KrbApRep(DerValue encoding, Credentials tgs_creds)

        throws KrbException, IOException {

        APRep rep = null;

        try {

            rep = new APRep(encoding);

        } catch (Asn1Exception e) {

            rep = null;

            KRBError err = new KRBError(encoding);

            String errStr = err.getErrorString();

            String eText;

            if (errStr.charAt(errStr.length() - 1) == 0)

                eText = errStr.substring(0, errStr.length() - 1);

            else

                eText = errStr;

            KrbException ke = new KrbException(err.getErrorCode(), eText);

            ke.initCause(e);

            throw ke;

        }

        byte[] temp = rep.encPart.decrypt(tgs_creds.key,

            KeyUsage.KU_ENC_AP_REP_PART);

        byte[] enc_ap_rep_part = rep.encPart.reset(temp, true);

        encoding = new DerValue(enc_ap_rep_part);

        encPart = new EncAPRepPart(encoding);

    }

    private void authenticate(KrbApReq apReq)

        throws KrbException, IOException {

        if (encPart.ctime.getSeconds() != apReq.getCtime().getSeconds() ||

            encPart.cusec != apReq.getCtime().getMicroSeconds())

            throw new KrbApErrException(Krb5.KRB_AP_ERR_MUT_FAIL);

    }

    /**

     * Returns the optional subkey stored in

     * this message. Returns null if none is stored.

     */

    public EncryptionKey getSubKey() {

        // XXX Can encPart be null

        return encPart.getSubKey();

    }

    /**

     * Returns the optional sequence number stored in the

     * this message. Returns null if none is stored.

     */

    public Integer getSeqNumber() {

        // XXX Can encPart be null

        return encPart.getSeqNumber();

    }

    /**

     * Returns the ASN.1 encoding that should be sent to the peer.

     */

    public byte[] getMessage() {

        return obuf;

    }

    private void createMessage(

                               EncryptionKey key,

                               KerberosTime ctime,

                               int cusec,

                               EncryptionKey subKey,

                               SeqNumber seqNumber)

        throws Asn1Exception, IOException,

               KdcErrException, KrbCryptoException {

        Integer seqno = null;

        if (seqNumber != null)

            seqno = new Integer(seqNumber.current());

        encPart = new EncAPRepPart(ctime,

                                   cusec,

                                   subKey,

                                   seqno);

        byte[] encPartEncoding = encPart.asn1Encode();

        EncryptedData encEncPart = new EncryptedData(key, encPartEncoding,

            KeyUsage.KU_ENC_AP_REP_PART);

        apRepMessg = new APRep(encEncPart);

    }

}