/*

 * Copyright (c) 2000, 2019, 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.

 */

/*

 *

 *  (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.krb5.internal.crypto.EType;

import sun.security.util.*;

import java.io.IOException;

import java.util.Objects;

import javax.security.auth.kerberos.KeyTab;

import sun.security.jgss.krb5.Krb5Util;

/**

 * This class encapsulates a AS-REP message that the KDC sends to the

 * client.

 */

class KrbAsRep extends KrbKdcRep {

    private ASRep rep;  // The AS-REP message

    private Credentials creds;  // The Credentials provide by the AS-REP

                                // message, created by initiator after calling

                                // the decrypt() method

    private boolean DEBUG = Krb5.DEBUG;

    KrbAsRep(byte[] ibuf) throws

            KrbException, Asn1Exception, IOException {

        DerValue encoding = new DerValue(ibuf);

        try {

            rep = new ASRep(encoding);

        } catch (Asn1Exception e) {

            rep = null;

            KRBError err = new KRBError(encoding);

            String errStr = err.getErrorString();

            String eText = null; // pick up text sent by the server (if any)

            if (errStr != null && errStr.length() > 0) {

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

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

                else

                    eText = errStr;

            }

            KrbException ke;

            if (eText == null) {

                // no text sent from server

                ke = new KrbException(err);

            } else {

                if (DEBUG) {

                    System.out.println("KRBError received: " + eText);

                }

                // override default text with server text

                ke = new KrbException(err, eText);

            }

            ke.initCause(e);

            throw ke;

        }

    }

    // KrbAsReqBuilder need to read back the PA for key generation

    PAData[] getPA() {

        return rep.pAData;

    }

    /**

     * Called by KrbAsReqBuilder to resolve a AS-REP message using a keytab.

     * @param ktab the keytab, not null

     * @param asReq the original AS-REQ sent, used to validate AS-REP

     * @param cname the user principal name, used to locate keys in ktab

     */

    void decryptUsingKeyTab(KeyTab ktab, KrbAsReq asReq, PrincipalName cname)

            throws KrbException, Asn1Exception, IOException {

        EncryptionKey dkey = null;

        int encPartKeyType = rep.encPart.getEType();

        Integer encPartKvno = rep.encPart.kvno;

            try {

                dkey = EncryptionKey.findKey(encPartKeyType, encPartKvno,

                        Krb5Util.keysFromJavaxKeyTab(ktab, cname));

            } catch (KrbException ke) {

                if (ke.returnCode() == Krb5.KRB_AP_ERR_BADKEYVER) {

                    // Fallback to no kvno. In some cases, keytab is generated

                    // not by sysadmin but Java's ktab command

                    dkey = EncryptionKey.findKey(encPartKeyType,

                            Krb5Util.keysFromJavaxKeyTab(ktab, cname));

                }

            }

            if (dkey == null) {

                throw new KrbException(Krb5.API_INVALID_ARG,

                    "Cannot find key for type/kvno to decrypt AS REP - " +

                    EType.toString(encPartKeyType) + "/" + encPartKvno);

            }

        decrypt(dkey, asReq, cname);

    }

    /**

     * Called by KrbAsReqBuilder to resolve a AS-REP message using a password.

     * @param password user provided password. not null

     * @param asReq the original AS-REQ sent, used to validate AS-REP

     * @param cname the user principal name, used to provide salt

     */

    void decryptUsingPassword(char[] password,

            KrbAsReq asReq, PrincipalName cname)

            throws KrbException, Asn1Exception, IOException {

        int encPartKeyType = rep.encPart.getEType();

        EncryptionKey dkey = EncryptionKey.acquireSecretKey(

                cname,

                password,

                encPartKeyType,

                PAData.getSaltAndParams(encPartKeyType, rep.pAData));

        decrypt(dkey, asReq, cname);

    }

    /**

     * Decrypts encrypted content inside AS-REP. Called by initiator.

     * @param dkey the decryption key to use

     * @param asReq the original AS-REQ sent, used to validate AS-REP

     */

    private void decrypt(EncryptionKey dkey, KrbAsReq asReq,

            PrincipalName cname)

            throws KrbException, Asn1Exception, IOException {

        byte[] enc_as_rep_bytes = rep.encPart.decrypt(dkey,

            KeyUsage.KU_ENC_AS_REP_PART);

        byte[] enc_as_rep_part = rep.encPart.reset(enc_as_rep_bytes);

        DerValue encoding = new DerValue(enc_as_rep_part);

        EncASRepPart enc_part = new EncASRepPart(encoding);

        rep.encKDCRepPart = enc_part;

        ASReq req = asReq.getMessage();

        check(true, req, rep, dkey);

        PrincipalName clientAlias = cname;

        if (clientAlias.equals(rep.cname))

            clientAlias = null;

        creds = new Credentials(

                                rep.ticket,

                                rep.cname,

                                clientAlias,

                                enc_part.sname,

                                null, // No server alias expected in a TGT

                                enc_part.key,

                                enc_part.flags,

                                enc_part.authtime,

                                enc_part.starttime,

                                enc_part.endtime,

                                enc_part.renewTill,

                                enc_part.caddr);

        if (DEBUG) {

            System.out.println(">>> KrbAsRep cons in KrbAsReq.getReply " +

                               req.reqBody.cname.getNameString());

        }

    }

    Credentials getCreds() {

        return Objects.requireNonNull(creds, "Creds not available yet.");

    }

    sun.security.krb5.internal.ccache.Credentials getCCreds() {

        return new sun.security.krb5.internal.ccache.Credentials(rep);

    }

}