/*

 * Copyright (c) 2000, 2013, 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.*;

import sun.security.jgss.krb5.Krb5AcceptCredential;

import java.net.InetAddress;

import sun.security.util.*;

import java.io.IOException;

import java.util.Arrays;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import sun.security.krb5.internal.rcache.AuthTimeWithHash;

/**

 * This class encapsulates a KRB-AP-REQ that a client sends to a

 * server for authentication.

 */

public class KrbApReq {

    private byte[] obuf;

    private KerberosTime ctime;

    private int cusec;

    private Authenticator authenticator;

    private Credentials creds;

    private APReq apReqMessg;

    // Used by acceptor side

    private static ReplayCache rcache = ReplayCache.getInstance();

    private static boolean DEBUG = Krb5.DEBUG;

    private static final char[] hexConst = "0123456789ABCDEF".toCharArray();

    private static final MessageDigest md;

    static {

        try {

            md = MessageDigest.getInstance("MD5");

        } catch (NoSuchAlgorithmException ex) {

            throw new RuntimeException("Impossible");

        }

    }

    /**

     * Constructs an AP-REQ message to send to the peer.

     * @param tgsCred the <code>Credentials</code> to be used to construct the

     *          AP Request  protocol message.

     * @param mutualRequired Whether mutual authentication is required

     * @param useSubkey Whether the subkey is to be used to protect this

     *        specific application session. If this is not set then the

     *        session key from the ticket will be used.

     * @throws KrbException for any Kerberos protocol specific error

     * @throws IOException for any IO related errors

     *          (e.g. socket operations)

     */

     /*

     // Not Used

    public KrbApReq(Credentials tgsCred,

                    boolean mutualRequired,

                    boolean useSubKey,

                    boolean useSeqNumber) throws Asn1Exception,

                    KrbCryptoException, KrbException, IOException {

        this(tgsCred, mutualRequired, useSubKey, useSeqNumber, null);

    }

*/

    /**

     * Constructs an AP-REQ message to send to the peer.

     * @param tgsCred the <code>Credentials</code> to be used to construct the

     *          AP Request  protocol message.

     * @param mutualRequired Whether mutual authentication is required

     * @param useSubkey Whether the subkey is to be used to protect this

     *        specific application session. If this is not set then the

     *        session key from the ticket will be used.

     * @param checksum checksum of the the application data that accompanies

     *        the KRB_AP_REQ.

     * @throws KrbException for any Kerberos protocol specific error

     * @throws IOException for any IO related errors

     *          (e.g. socket operations)

     */

     // Used in InitSecContextToken

    public KrbApReq(Credentials tgsCred,

                    boolean mutualRequired,

                    boolean useSubKey,

                    boolean useSeqNumber,

                    Checksum cksum) throws Asn1Exception,

                    KrbCryptoException, KrbException, IOException  {

        APOptions apOptions = (mutualRequired?

                               new APOptions(Krb5.AP_OPTS_MUTUAL_REQUIRED):

                               new APOptions());

        if (DEBUG)

            System.out.println(">>> KrbApReq: APOptions are " + apOptions);

        EncryptionKey subKey = (useSubKey?

                                new EncryptionKey(tgsCred.getSessionKey()):

                                null);

        SeqNumber seqNum = new LocalSeqNumber();

        init(apOptions,

             tgsCred,

             cksum,

             subKey,

             seqNum,

             null,   // AuthorizationData authzData

            KeyUsage.KU_AP_REQ_AUTHENTICATOR);

    }

    /**

     * Constructs an AP-REQ message from the bytes received from the

     * peer.

     * @param message The message received from the peer

     * @param keys <code>EncrtyptionKey</code>s to decrypt the message;

     *       key selected will depend on etype used to encrypte data

     * @throws KrbException for any Kerberos protocol specific error

     * @throws IOException for any IO related errors

     *          (e.g. socket operations)

     */

     // Used in InitSecContextToken (for AP_REQ and not TGS REQ)

    public KrbApReq(byte[] message,

                    Krb5AcceptCredential cred,

                    InetAddress initiator)

        throws KrbException, IOException {

        obuf = message;

        if (apReqMessg == null)

            decode();

        authenticate(cred, initiator);

    }

    /**

     * Constructs an AP-REQ message from the bytes received from the

     * peer.

     * @param value The <code>DerValue</code> that contains the

     *              DER enoded AP-REQ protocol message

     * @param keys <code>EncrtyptionKey</code>s to decrypt the message;

     *

     * @throws KrbException for any Kerberos protocol specific error

     * @throws IOException for any IO related errors

     *          (e.g. socket operations)

     */

     /*

    public KrbApReq(DerValue value, EncryptionKey[] key, InetAddress initiator)

        throws KrbException, IOException {

        obuf = value.toByteArray();

        if (apReqMessg == null)

            decode(value);

        authenticate(keys, initiator);

    }

    KrbApReq(APOptions options,

             Credentials tgs_creds,

             Checksum cksum,

             EncryptionKey subKey,

             SeqNumber seqNumber,

             AuthorizationData authorizationData)

        throws KrbException, IOException {

        init(options, tgs_creds, cksum, subKey, seqNumber, authorizationData);

    }

*/

     /** used by KrbTgsReq **/

    KrbApReq(APOptions apOptions,

             Ticket ticket,

             EncryptionKey key,

             PrincipalName cname,

             Checksum cksum,

             KerberosTime ctime,

             EncryptionKey subKey,

             SeqNumber seqNumber,

        AuthorizationData authorizationData)

        throws Asn1Exception, IOException,

               KdcErrException, KrbCryptoException {

        init(apOptions, ticket, key, cname,

             cksum, ctime, subKey, seqNumber, authorizationData,

            KeyUsage.KU_PA_TGS_REQ_AUTHENTICATOR);

    }

    private void init(APOptions options,

                      Credentials tgs_creds,

                      Checksum cksum,

                      EncryptionKey subKey,

                      SeqNumber seqNumber,

                      AuthorizationData authorizationData,

        int usage)

        throws KrbException, IOException {

        ctime = KerberosTime.now();

        init(options,

             tgs_creds.ticket,

             tgs_creds.key,

             tgs_creds.client,

             cksum,

             ctime,

             subKey,

             seqNumber,

             authorizationData,

            usage);

    }

    private void init(APOptions apOptions,

                      Ticket ticket,

                      EncryptionKey key,

                      PrincipalName cname,

                      Checksum cksum,

                      KerberosTime ctime,

                      EncryptionKey subKey,

                      SeqNumber seqNumber,

                      AuthorizationData authorizationData,

        int usage)

        throws Asn1Exception, IOException,

               KdcErrException, KrbCryptoException {

        createMessage(apOptions, ticket, key, cname,

                      cksum, ctime, subKey, seqNumber, authorizationData,

            usage);

        obuf = apReqMessg.asn1Encode();

    }

    void decode() throws KrbException, IOException {

        DerValue encoding = new DerValue(obuf);

        decode(encoding);

    }

    void decode(DerValue encoding) throws KrbException, IOException {

        apReqMessg = null;

        try {

            apReqMessg = new APReq(encoding);

        } catch (Asn1Exception e) {

            apReqMessg = 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;

        }

    }

    private void authenticate(Krb5AcceptCredential cred, InetAddress initiator)

        throws KrbException, IOException {

        int encPartKeyType = apReqMessg.ticket.encPart.getEType();

        Integer kvno = apReqMessg.ticket.encPart.getKeyVersionNumber();

        EncryptionKey[] keys = cred.getKrb5EncryptionKeys(apReqMessg.ticket.sname);

        EncryptionKey dkey = EncryptionKey.findKey(encPartKeyType, kvno, keys);

        if (dkey == null) {

            throw new KrbException(Krb5.API_INVALID_ARG,

                "Cannot find key of appropriate type to decrypt AP-REQ - " +

                                   EType.toString(encPartKeyType));

        }

        byte[] bytes = apReqMessg.ticket.encPart.decrypt(dkey,

            KeyUsage.KU_TICKET);

        byte[] temp = apReqMessg.ticket.encPart.reset(bytes);

        EncTicketPart enc_ticketPart = new EncTicketPart(temp);

        checkPermittedEType(enc_ticketPart.key.getEType());

        byte[] bytes2 = apReqMessg.authenticator.decrypt(enc_ticketPart.key,

            KeyUsage.KU_AP_REQ_AUTHENTICATOR);

        byte[] temp2 = apReqMessg.authenticator.reset(bytes2);

        authenticator = new Authenticator(temp2);

        ctime = authenticator.ctime;

        cusec = authenticator.cusec;

        authenticator.ctime =

                authenticator.ctime.withMicroSeconds(authenticator.cusec);

        if (!authenticator.cname.equals(enc_ticketPart.cname)) {

            throw new KrbApErrException(Krb5.KRB_AP_ERR_BADMATCH);

        }

        if (!authenticator.ctime.inClockSkew())

            throw new KrbApErrException(Krb5.KRB_AP_ERR_SKEW);

        byte[] hash = md.digest(apReqMessg.authenticator.cipher);

        char[] h = new char[hash.length * 2];

        for (int i=0; i<hash.length; i++) {

            h[2*i] = hexConst[(hash[i]&0xff)>>4];

            h[2*i+1] = hexConst[hash[i]&0xf];

        }

        AuthTimeWithHash time = new AuthTimeWithHash(

                authenticator.cname.toString(),

                apReqMessg.ticket.sname.toString(),

                authenticator.ctime.getSeconds(),

                authenticator.cusec,

                new String(h));

        rcache.checkAndStore(KerberosTime.now(), time);

        if (initiator != null) {

            // sender host address

            HostAddress sender = new HostAddress(initiator);

            if (enc_ticketPart.caddr != null

                    && !enc_ticketPart.caddr.inList(sender)) {

                if (DEBUG) {

                    System.out.println(">>> KrbApReq: initiator is "

                            + sender.getInetAddress()

                            + ", but caddr is "

                            + Arrays.toString(

                                enc_ticketPart.caddr.getInetAddresses()));

                }

                throw new KrbApErrException(Krb5.KRB_AP_ERR_BADADDR);

            }

        }

        // XXX check for repeated authenticator

        // if found

        //    throw new KrbApErrException(Krb5.KRB_AP_ERR_REPEAT);

        // else

        //    save authenticator to check for later

        KerberosTime now = KerberosTime.now();

        if ((enc_ticketPart.starttime != null &&

             enc_ticketPart.starttime.greaterThanWRTClockSkew(now)) ||

            enc_ticketPart.flags.get(Krb5.TKT_OPTS_INVALID))

            throw new KrbApErrException(Krb5.KRB_AP_ERR_TKT_NYV);

        // if the current time is later than end time by more

        // than the allowable clock skew, throws ticket expired exception.

        if (enc_ticketPart.endtime != null &&

            now.greaterThanWRTClockSkew(enc_ticketPart.endtime)) {

            throw new KrbApErrException(Krb5.KRB_AP_ERR_TKT_EXPIRED);

        }

        creds = new Credentials(

                                apReqMessg.ticket,

                                authenticator.cname,

                                apReqMessg.ticket.sname,

                                enc_ticketPart.key,

                                enc_ticketPart.flags,

                                enc_ticketPart.authtime,

                                enc_ticketPart.starttime,

                                enc_ticketPart.endtime,

                                enc_ticketPart.renewTill,

                                enc_ticketPart.caddr,

                                enc_ticketPart.authorizationData);

        if (DEBUG) {

            System.out.println(">>> KrbApReq: authenticate succeed.");

        }

    }

    /**

     * Returns the credentials that are contained in the ticket that

     * is part of this AP-REQ.

     */

    public Credentials getCreds() {

        return creds;

    }

    KerberosTime getCtime() {

        if (ctime != null)

            return ctime;

        return authenticator.ctime;

    }

    int cusec() {

        return cusec;

    }

    APOptions getAPOptions() throws KrbException, IOException {

        if (apReqMessg == null)

            decode();

        if (apReqMessg != null)

            return apReqMessg.apOptions;

        return null;

    }

    /**

     * Returns true if mutual authentication is required and hence an

     * AP-REP will need to be generated.

     * @throws KrbException

     * @throws IOException

     */

    public boolean getMutualAuthRequired() throws KrbException, IOException {

        if (apReqMessg == null)

            decode();

        if (apReqMessg != null)

            return apReqMessg.apOptions.get(Krb5.AP_OPTS_MUTUAL_REQUIRED);

        return false;

    }

    boolean useSessionKey() throws KrbException, IOException {

        if (apReqMessg == null)

            decode();

        if (apReqMessg != null)

            return apReqMessg.apOptions.get(Krb5.AP_OPTS_USE_SESSION_KEY);

        return false;

    }

    /**

     * Returns the optional subkey stored in the Authenticator for

     * this message. Returns null if none is stored.

     */

    public EncryptionKey getSubKey() {

        // XXX Can authenticator be null

        return authenticator.getSubKey();

    }

    /**

     * Returns the optional sequence number stored in the

     * Authenticator for this message. Returns null if none is

     * stored.

     */

    public Integer getSeqNumber() {

        // XXX Can authenticator be null

        return authenticator.getSeqNumber();

    }

    /**

     * Returns the optional Checksum stored in the

     * Authenticator for this message. Returns null if none is

     * stored.

     */

    public Checksum getChecksum() {

        return authenticator.getChecksum();

    }

    /**

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

     */

    public byte[] getMessage() {

        return obuf;

    }

    /**

     * Returns the principal name of the client that generated this

     * message.

     */

    public PrincipalName getClient() {

        return creds.getClient();

    }

    private void createMessage(APOptions apOptions,

                               Ticket ticket,

                               EncryptionKey key,

                               PrincipalName cname,

                               Checksum cksum,

                               KerberosTime ctime,

                               EncryptionKey subKey,

                               SeqNumber seqNumber,

                               AuthorizationData authorizationData,

        int usage)

        throws Asn1Exception, IOException,

               KdcErrException, KrbCryptoException {

        Integer seqno = null;

        if (seqNumber != null)

        authenticator =

            new Authenticator(cname,

                              cksum,

                              ctime.getMicroSeconds(),

                              ctime,

                              subKey,

                              seqno,

                              authorizationData);

        byte[] temp = authenticator.asn1Encode();

        EncryptedData encAuthenticator =

            new EncryptedData(key, temp, usage);

        apReqMessg =

            new APReq(apOptions, ticket, encAuthenticator);

    }

     // Check that key is one of the permitted types

     private static void checkPermittedEType(int target) throws KrbException {

        int[] etypes = EType.getDefaults("permitted_enctypes");

        if (!EType.isSupported(target, etypes)) {

            throw new KrbException(EType.toString(target) +

                " encryption type not in permitted_enctypes list");

        }

     }

}