/*

 * Copyright (c) 2000, 2018, 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 sun.security.jgss.krb5;

import org.ietf.jgss.*;

import java.io.InputStream;

import java.io.IOException;

import sun.security.action.GetPropertyAction;

import sun.security.krb5.*;

import java.net.InetAddress;

import sun.security.krb5.internal.AuthorizationData;

import sun.security.krb5.internal.KerberosTime;

class InitSecContextToken extends InitialToken {

    // If non-mutual authentication is requested, there is no AP-REP message.

    // The acceptor thus has no chance to send the seq-number field to the

    // initiator. In this case, the initiator and acceptor should has an

    // agreement to derive acceptor's initial seq-number if the acceptor wishes

    // to send messages to the initiator.

    // If this flag is true, it will the same as the initiator's initial

    // seq-number (as MIT krb5 and Windows SSPI do). Otherwise, it will be zero

    // (as Heimdal does). The default value is true.

    private static final boolean ACCEPTOR_USE_INITIATOR_SEQNUM;

    static {

        // The ACCEPTOR_USE_INITIATOR_SEQNUM value is determined by the system

        // property "sun.security.krb5.acceptor.sequence.number.nonmutual",

        // which can be set to "initiator", "zero" or "0".

        String propName = "sun.security.krb5.acceptor.sequence.number.nonmutual";

        String s = GetPropertyAction.privilegedGetProperty(propName, "initiator");

        if (s.equals("initiator")) {

            ACCEPTOR_USE_INITIATOR_SEQNUM = true;

        } else if (s.equals("zero") || s.equals("0")) {

            ACCEPTOR_USE_INITIATOR_SEQNUM = false;

        } else {

            throw new AssertionError("Unrecognized value for " + propName

                    + ": " + s);

        }

    }

    private KrbApReq apReq = null;

    /**

     * For the context initiator to call. It constructs a new

     * InitSecContextToken to send over to the peer containing the desired

     * flags and the AP-REQ. It also updates the context with the local

     * sequence number and shared context key.

     * (When mutual auth is enabled the peer has an opportunity to

     * renegotiate the session key in the followup AcceptSecContextToken

     * that it sends.)

     */

    InitSecContextToken(Krb5Context context,

                               Credentials tgt,

                               Credentials serviceTicket)

        throws KrbException, IOException, GSSException {

        boolean mutualRequired = context.getMutualAuthState();

        boolean useSubkey = true; // MIT Impl will crash if this is not set!

        boolean useSequenceNumber = true;

        OverloadedChecksum gssChecksum =

            new OverloadedChecksum(context, tgt, serviceTicket);

        Checksum checksum = gssChecksum.getChecksum();

        context.setTktFlags(serviceTicket.getFlags());

        context.setAuthTime(

                new KerberosTime(serviceTicket.getAuthTime()).toString());

        apReq = new KrbApReq(serviceTicket,

                             mutualRequired,

                             useSubkey,

                             useSequenceNumber,

                             checksum);

        context.resetMySequenceNumber(apReq.getSeqNumber().intValue());

        EncryptionKey subKey = apReq.getSubKey();

        if (subKey != null)

            context.setKey(Krb5Context.INITIATOR_SUBKEY, subKey);

        else

            context.setKey(Krb5Context.SESSION_KEY, serviceTicket.getSessionKey());

        if (!mutualRequired)

            context.resetPeerSequenceNumber(

                    ACCEPTOR_USE_INITIATOR_SEQNUM

                    ? apReq.getSeqNumber().intValue()

                    : 0);

    }

    /**

     * For the context acceptor to call. It reads the bytes out of an

     * InputStream and constructs an InitSecContextToken with them.

     */

    InitSecContextToken(Krb5Context context, Krb5AcceptCredential cred,

                               InputStream is)

        throws IOException, GSSException, KrbException  {

        int tokenId = ((is.read()<<8) | is.read());

        if (tokenId != Krb5Token.AP_REQ_ID)

            throw new GSSException(GSSException.DEFECTIVE_TOKEN, -1,

                                   "AP_REQ token id does not match!");

        // XXX Modify KrbApReq cons to take an InputStream

        byte[] apReqBytes =

            new sun.security.util.DerValue(is).toByteArray();

        //debug("=====ApReqBytes: [" + getHexBytes(apReqBytes) + "]\n");

        InetAddress addr = null;

        if (context.getChannelBinding() != null) {

            addr = context.getChannelBinding().getInitiatorAddress();

        }

        apReq = new KrbApReq(apReqBytes, cred, addr);

        //debug("\nReceived AP-REQ and authenticated it.\n");

        EncryptionKey sessionKey = apReq.getCreds().getSessionKey();

        /*

          System.out.println("\n\nSession key from service ticket is: " +

          getHexBytes(sessionKey.getBytes()));

        */

        EncryptionKey subKey = apReq.getSubKey();

        if (subKey != null) {

            context.setKey(Krb5Context.INITIATOR_SUBKEY, subKey);

            /*

              System.out.println("Sub-Session key from authenticator is: " +

              getHexBytes(subKey.getBytes()) + "\n");

            */

        } else {

            context.setKey(Krb5Context.SESSION_KEY, sessionKey);

            //System.out.println("Sub-Session Key Missing in Authenticator.\n");

        }

        OverloadedChecksum gssChecksum = new OverloadedChecksum(

                context, apReq.getChecksum(), sessionKey, subKey);

        gssChecksum.setContextFlags(context);

        Credentials delegCred = gssChecksum.getDelegatedCreds();

        if (delegCred != null) {

            Krb5CredElement credElement =

                Krb5InitCredential.getInstance(

                                   (Krb5NameElement)context.getSrcName(),

                                   delegCred);

            context.setDelegCred(credElement);

        }

        Integer apReqSeqNumber = apReq.getSeqNumber();

        int peerSeqNumber = (apReqSeqNumber != null ?

                             apReqSeqNumber.intValue() :

                             0);

        context.resetPeerSequenceNumber(peerSeqNumber);

        if (!context.getMutualAuthState()) {

            context.resetMySequenceNumber(

                    ACCEPTOR_USE_INITIATOR_SEQNUM

                            ? peerSeqNumber

                            : 0);

        }

        context.setAuthTime(

                new KerberosTime(apReq.getCreds().getAuthTime()).toString());

        context.setTktFlags(apReq.getCreds().getFlags());

        AuthorizationData ad = apReq.getCreds().getAuthzData();

        context.setAuthzData(ad);

    }

    public final KrbApReq getKrbApReq() {

        return apReq;

    }

    public final byte[] encode() throws IOException {

        byte[] apReqBytes = apReq.getMessage();

        byte[] retVal = new byte[2 + apReqBytes.length];

        writeInt(Krb5Token.AP_REQ_ID, retVal, 0);

        System.arraycopy(apReqBytes, 0, retVal, 2, apReqBytes.length);

        //      System.out.println("GSS-Token with AP_REQ is:");

        //      System.out.println(getHexBytes(retVal));

        return retVal;

    }

}