/*

 * 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.  Sun designates this

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

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.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.internal;

import sun.security.krb5.*;

import sun.security.krb5.internal.ccache.CredentialsCache;

import java.util.StringTokenizer;

import sun.security.krb5.internal.ktab.*;

import java.io.File;

import java.io.IOException;

import java.util.Date;

import java.util.Vector;

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.io.UnsupportedEncodingException;

import java.net.InetAddress;

/**

 * This class is a utility that contains much of the TGS-Exchange

 * protocol. It is used by ../Credentials.java for service ticket

 * acquisition in both the normal and the x-realm case.

 */

public class CredentialsUtil {

    private static boolean DEBUG = sun.security.krb5.internal.Krb5.DEBUG;

   /**

    * Acquires credentials for a specified service using initial credential. Wh

en the service has a different realm

    * from the initial credential, we do cross-realm authentication - first, we

 use the current credential to get

    * a cross-realm credential from the local KDC, then use that cross-realm cr

edential to request service credential

    * from the foreigh KDC.

    *

    * @param service the name of service principal using format components@real

m

    * @param ccreds client's initial credential.

    * @exception Exception general exception will be thrown when any error occu

rs.

    * @return a <code>Credentials</code> object.

    */

    public static Credentials acquireServiceCreds(

                String service, Credentials ccreds)

    throws KrbException, IOException {

        ServiceName sname = new ServiceName(service);

        String serviceRealm = sname.getRealmString();

        String localRealm = ccreds.getClient().getRealmString();

        String defaultRealm = Config.getInstance().getDefaultRealm();

        if (localRealm == null) {

            PrincipalName temp = null;

            if ((temp = ccreds.getServer()) != null)

                localRealm = temp.getRealmString();

        }

        if (localRealm == null) {

            localRealm = defaultRealm;

        }

        if (serviceRealm == null) {

            serviceRealm = localRealm;

            sname.setRealm(serviceRealm);

        }

        /*

          if (!localRealm.equalsIgnoreCase(serviceRealm)) { //do cross-realm auth entication

          if (DEBUG) {

          System.out.println(">>>DEBUG: Credentails request cross realm ticket for " + "krbtgt/" + serviceRealm + "@" + localRealm);

          }

          Credentials crossCreds = serviceCreds(new ServiceName("krbtgt/" + serviceRealm + "@" + localRealm), ccreds);

          if (DEBUG) {

          printDebug(crossCreds);

          }

          Credentials result = serviceCreds(sname, crossCreds);

          if (DEBUG) {

          printDebug(result);

          }

          return result;

          }

          else return serviceCreds(sname, ccreds);

        */

        if (localRealm.equals(serviceRealm))

        {

            if (DEBUG)

                System.out.println(">>> Credentials acquireServiceCreds: same realm");

            return serviceCreds(sname, ccreds);

        }

        // Get a list of realms to traverse

        String[] realms = Realm.getRealmsList(localRealm, serviceRealm);

        if (realms == null || realms.length == 0)

        {

            if (DEBUG)

                System.out.println(">>> Credentials acquireServiceCreds: no realms list");

            return null;

        }

        int i = 0, k = 0;

        Credentials cTgt = null, newTgt = null, theTgt = null;

        ServiceName tempService = null;

        String realm = null, newTgtRealm = null, theTgtRealm = null;

        for (cTgt = ccreds, i = 0; i < realms.length;)

        {

            tempService = new ServiceName(PrincipalName.TGS_DEFAULT_SRV_NAME,

                                          serviceRealm, realms[i]);

            if (DEBUG)

            {

                System.out.println(">>> Credentials acquireServiceCreds: main loop: [" + i +"] tempService=" + tempService);

            }

            try {

                newTgt = serviceCreds(tempService, cTgt);

            } catch (Exception exc) {

                newTgt = null;

            }

            if (newTgt == null)

            {

                if (DEBUG)

                {

                    System.out.println(">>> Credentials acquireServiceCreds: no tgt; searching backwards");

                }

                /*

                 * No tgt found. Try to get one for a

                 * realm as close to the target as possible.

                 * That means traversing the realms list backwards.

                 */

                for (newTgt = null, k = realms.length - 1;

                     newTgt == null && k > i; k--)

                {

                    tempService = new ServiceName(

                                       PrincipalName.TGS_DEFAULT_SRV_NAME,

                                       realms[k], realms[i]);

                    if (DEBUG)

                    {

                        System.out.println(">>> Credentials acquireServiceCreds: inner loop: [" + k +"] tempService=" + tempService);

                    }

                    try {

                        newTgt = serviceCreds(tempService, cTgt);

                    } catch (Exception exc) {

                        newTgt = null;

                    }

                }

            } // Ends 'if (newTgt == null)'

            if (newTgt == null)

            {

                if (DEBUG)

                {

                    System.out.println(">>> Credentials acquireServiceCreds: no tgt; cannot get creds");

                }

                break;

            }

            /*

             * We have a tgt. It may or may not be for the target.

             * If it's for the target realm, we're done looking for a tgt.

             */

            newTgtRealm = newTgt.getServer().getInstanceComponent();

            if (DEBUG)

            {

                System.out.println(">>> Credentials acquireServiceCreds: got tgt");

                //printDebug(newTgt);

            }

            if (newTgtRealm.equals(serviceRealm))

            {

                /* We got the right tgt */

                theTgt = newTgt;

                theTgtRealm = newTgtRealm;

                break;

            }

            /*

             * The new tgt is not for the target realm.

             * See if the realm of the new tgt is in the list of realms

             * and continue looking from there.

             */

            for (k = i+1; k < realms.length; k++)

            {

                if (newTgtRealm.equals(realms[k]))

                {

                    break;

                }

            }

            if (k < realms.length)

            {

                /*

                 * (re)set the counter so we start looking

                 * from the realm we just obtained a tgt for.

                 */

                i = k;

                cTgt = newTgt;

                if (DEBUG)

                {

                    System.out.println(">>> Credentials acquireServiceCreds: continuing with main loop counter reset to " + i);

                }

                continue;

            }

            else

            {

                /*

                 * The new tgt's realm is not in the heirarchy of realms.

                 * It's probably not safe to get a tgt from

                 * a tgs that is outside the known list of realms.

                 * Give up now.

                 */

                break;

            }

        } // Ends outermost/main 'for' loop

        Credentials theCreds = null;

        if (theTgt != null)

        {

            /* We have the right tgt. Let's get the service creds */

            if (DEBUG)

            {

                System.out.println(">>> Credentials acquireServiceCreds: got right tgt");

                //printDebug(theTgt);

                System.out.println(">>> Credentials acquireServiceCreds: obtaining service creds for " + sname);

            }

            try {

                theCreds = serviceCreds(sname, theTgt);

            } catch (Exception exc) {

              if (DEBUG)

                System.out.println(exc);

              theCreds = null;

            }

        }

        if (theCreds != null)

        {

            if (DEBUG)

            {

                System.out.println(">>> Credentials acquireServiceCreds: returning creds:");

                Credentials.printDebug(theCreds);

            }

            return theCreds;

        }

        throw new KrbApErrException(Krb5.KRB_AP_ERR_GEN_CRED,

                                    "No service creds");

    }

   /*

    * This method does the real job to request the service credential.

    */

    private static Credentials serviceCreds(

            ServiceName service, Credentials ccreds)

            throws KrbException, IOException {

        return new KrbTgsReq(ccreds, service).sendAndGetCreds();

    }

}