/*
 * %W% %E%
 *
 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */


package com.sun.security.auth.module;

import java.io.*;
import java.net.*;
import java.text.MessageFormat;
import java.util.*;

import javax.security.auth.*;
import javax.security.auth.kerberos.*;
import javax.security.auth.callback.*;
import javax.security.auth.login.*;
import javax.security.auth.spi.*;

import sun.security.krb5.*;
import sun.security.krb5.Config;
import sun.security.krb5.RealmException;
import sun.security.util.AuthResources;
import sun.security.jgss.krb5.Krb5Util;
import sun.security.krb5.Credentials;
import sun.misc.HexDumpEncoder;

/**
 * <p> This <code>LoginModule</code> authenticates users using 
 * Kerberos protocols. 
 *
 * <p> The configuration entry for <code>Krb5LoginModule</code> has 
 * several options that control the authentication process and 
 * additions to the <code>Subject</code>'s private credential
 * set. Irrespective of these options, the <code>Subject</code>'s
 * principal set and private credentials set are updated only when 
 * <code>commit</code> is called.
 * When <code>commit</code> is called, the <code>KerberosPrincipal</code>
 * is added to the  <code>Subject</code>'s
 * principal set and <code>KerberosTicket</code> is
 * added to the <code>Subject</code>'s private credentials.
 *
 * <p> If the configuration entry for <code>KerberosLoginModule</code> 
 * has the option <code>storeKey</code> set to true, then  
 * <code>KerberosKey</code> will also be added to the 
 * subject's private credentials. <code>KerberosKey</code>, the principal's
 * key will be either obtained from the keytab or
 * derived from user's password.
 * 
 * <p> This <code>LoginModule</code> recognizes the <code>doNotPrompt</code> 
 * option. If set to true the user will not be prompted for the password.
 *
 * <p> The user can  specify the location of the ticket cache by using 
 * the option <code>ticketCache</code> in the configuration entry. 
 * 
 * <p>The user can specify the keytab location by using 
 * the option <code>keyTab</code>
 * in the configuration entry.
 *
 * <p> The principal name can be specified in the configuration entry 
 * by using the option <code>principal</code>. The principal name 
 * can either be a simple user name or a service name such as
 * <code>host/mission.eng.sun.com</code>. The principal can also 
 * be set using the system property <code>sun.security.krb5.principal</code>. 
 * This property is checked during login. If this property is not set, then
 * the principal name from the configuration is used. In the
 * case where the principal property is not set and the principal
 * entry also does not exist, the user is prompted for the name.   
 *
 * <p> The following is a list of configuration options supported 
 * for <code>Krb5LoginModule</code>:
 * <dl>
 * <blockquote><dt><b><code>refreshKrb5Config</code></b>:</dt>
 * <dd> Set this to true, if you want the configuration
 * to be refreshed before the <code>login</code> method is called.</dd>
 * <P>
 * <dt><b><code>useTicketCache</code></b>:</dt> 
 * <dd>Set this to true, if you want the 
 * TGT to be obtained
 * from the ticket cache. Set this option 
 * to false if you do not want this module to use the ticket cache.
 * (Default is False).
 * This module will 
 * search for the tickect 
 * cache in the following locations:
 * For Windows 2000, it will use Local Security Authority (LSA) API 
 * to get the TGT. On Solaris and Linux 
 * it will look for the ticket cache in /tmp/krb5cc_<code>uid</code>
 * where the uid is numeric user
 * identifier. If the ticket cache is 
 * not available in either of the above locations, or if we are on a
 * different Windows platform,  it will look for the cache as 
 * {user.home}{file.separator}krb5cc_{user.name}.
 * You can override the ticket cache location by using
 * <code>ticketCache</code> 
 * <P>
 * <dt><b><code>ticketCache</code></b>:</dt> 
 * <dd>Set this to the name of the ticket 
 * cache that  contains user's TGT. 
 * If this is set,  <code>useTicketCache</code> 
 * must also be set to true; Otherwise a configuration error will 
 * be returned.</dd>
 *  <P> 
 * <dt><b><code>renewTGT</code></b>:</dt> 
 * <dd>Set this to true, if you want to renew
 * the TGT. If this is set, <code>useTicketCache</code> must also be 
 * set to true; otherwise a configuration error will be returned.</dd> 
 * <p>
 * <dt><b><code>doNotPrompt</code></b>:</dt> 
 * <dd>Set this to true if you do not want to be
 * prompted for the password 
 * if credentials can 
 * not be obtained from the cache or keytab.(Default is false)  
 * If set to true authentication will fail if credentials can 
 * not be obtained from the cache or keytab.</dd> 
 * <P>
 * <dt><b><code>useKeyTab</code></b>:</dt> 
 * <dd>Set this to true if you 
 * want the module to get the principal's key from the
 * the keytab.(default value is False) 
 * If <code>keyatb</code> 
 * is not set then
 * the module will locate the keytab from the 
 * Kerberos configuration file.</dd> 
 * If it is not specifed in the Kerberos configuration file 
 * then it will look for the file
 * <code>{user.home}{file.separator}</code>krb5.keytab.</dd>
 * <P>
 * <dt><b><code>keyTab</code></b>:</dt> 
 * <dd>Set this to the file name of the 
 * keytab to get principal's secret key.</dd>
 * <P>
 * <dt><b><code>storeKey</code></b>:</dt> 
 * <dd>Set this to true to if you want the
 * principal's key to be stored in the Subject's private credentials. </dd>
 * <p> 
 * <dt><b><code>principal</code></b>:</dt>
 * <dd>The name of the principal that should 
 * be used. The principal can be a simple username such as 
 * "<code>testuser</code>" or a service name such as
 * "<code>host/testhost.eng.sun.com</code>". You can use the
 * <code>principal</code>  option to set the principal when there are
 * credentials for multiple principals in the
 * <code>keyTab</code> or when you want a specific ticket cache only.  
 * The principal can also be set using the system property 
 * <code>sun.security.krb5.principal</code>. In addition, if this 
 * system property is defined, then it will be used. If this property 
 * is not set, then the principal name from the configuration will be 
 * used.</dd>
 * <P>
 * <dt><b><code>isInitiator</code></b>:</dt> 
 * <dd>Set this to true, if initiator. Set this to false, if acceptor only.
 * (Default is true).
 * Note: Do not set this value to false for initiators.</dd>
 * </dl></blockquote>
 *
 * <p> This <code>LoginModule</code> also recognizes the following additional 
 * <code>Configuration</code>
 * options that enable you to share username and passwords across different 
 * authentication modules:
 * <pre>
 *
 *    useFirstPass   if, true, this LoginModule retrieves the
 *                   username and password from the module's shared state,
 *                   using "javax.security.auth.login.name" and
 *                   "javax.security.auth.login.password" as the respective
 *                   keys. The retrieved values are used for authentication.
 *                   If authentication fails, no attempt for a retry
 *                   is made, and the failure is reported back to the
 *                   calling application.
 *
 *    tryFirstPass   if, true, this LoginModule retrieves the
 *                   the username and password from the module's shared
 *                   state using "javax.security.auth.login.name" and
 *                   "javax.security.auth.login.password" as the respective
 *                   keys.  The retrieved values are used for
 *                   authentication.
 *                   If authentication fails, the module uses the
 *                   CallbackHandler to retrieve a new username
 *                   and password, and another attempt to authenticate
 *                   is made. If the authentication fails, 
 *                   the failure is reported back to the calling application
 *
 *    storePass      if, true, this LoginModule stores the username and
 *                   password obtained from the CallbackHandler in the
 *                   modules shared state, using 
 *                   "javax.security.auth.login.name" and 
 *                   "javax.security.auth.login.password" as the respective
 *                   keys.  This is not performed if existing values already
 *                   exist for the username and password in the shared
 *                   state, or if authentication fails.
 *
 *    clearPass     if, true, this <code>LoginModule</code> clears the
 *                  username and password stored in the module's shared
 *                  state  after both phases of authentication
 *                  (login and commit)  have completed.
 * </pre>
 * <p>Examples of some configuration values for Krb5LoginModule in 
 * JAAS config file and the results are:
 * <ul>
 * <p> <code>doNotPrompt</code>=true;
 * </ul>
 * <p> This is an illegal combination since <code>useTicketCache</code>
 * is not set and the user can not be prompted for the password.
 *<ul>
 * <p> <code>ticketCache</code> = < filename >;
 *</ul>
 * <p> This is an illegal combination since <code>useTicketCache</code>
 * is not set to true and the ticketCache is set. A configuration error
 * will occur.
 * <ul>
 * <p> <code>renewTGT</code>=true;
 *</ul>
 * <p> This is an illegal combination since <code>useTicketCache</code> is
 * not set to true and renewTGT is set. A configuration error will occur.
 * <ul>
 * <p> <code>storeKey</code>=true
 * <code>useTicketCache</code> = true
 * <code>doNotPrompt</code>=true;;
 *</ul>
 * <p> This is an illegal combination since  <code>storeKey</code> is set to
 * true but the key can not be obtained either by prompting the user or from
 * the keytab.A configuration error will occur.
 * <ul>
 * <p>  <code>keyTab</code> = < filename > <code>doNotPrompt</code>=true ;
 * </ul>
 * <p>This is an illegal combination since useKeyTab is not set to true and
 * the keyTab is set. A configuration error will occur.
 * <ul>
 * <p> <code>debug=true </code>
 *</ul>
 * <p> Prompt the user for the principal name and the password.
 * Use the authentication exchange to get TGT from the KDC and 
 * populate the <code>Subject</code> with the principal and TGT. 
 * Output debug messages.
 * <ul>
 * <p> <code>useTicketCache</code> = true <code>doNotPrompt</code>=true;
 *</ul>
 * <p>Check the default cache for TGT and populate the <code>Subject</code>
 * with the principal and TGT. If the TGT is not available, 
 * do not prompt the user, instead fail the authentication.
 * <ul>
 * <p><code>principal</code>=< name ><code>useTicketCache</code> = true 
 * <code>doNotPrompt</code>=true;
 *</ul>
 * <p> Get the TGT from the default cache for the principal and populate the
 * Subject's principal and private creds set. If ticket cache is
 * not available or does not contain the principal's TGT 
 * authentication will fail.
 * <ul>
 * <p> <code>useTicketCache</code> = true 
 * <code>ticketCache</code>=< file name ><code>useKeyTab</code> = true 
 * <code> keyTab</code>=< keytab filename >
 * <code>principal</code> = < principal name >
 * <code>doNotPrompt</code>=true;
 *</ul>
 * <p>  Search the cache for the principal's TGT. If it is not available 
 * use the key in the keytab to perform authentication exchange with the 
 * KDC and acquire the TGT.
 * The Subject will be populated with the principal and the TGT.
 * If the key is not available or valid then authentication will fail.
 * <ul>
 * <p><code>useTicketCache</code> = true 
 * <code>ticketCache</code>=< file name >
 *</ul>
 * <p> The TGT will be obtained from the cache specified. 
 * The Kerberos principal name used will be the principal name in
 * the Ticket cache. If the TGT is not available in the
 * ticket cache the user will be prompted for the principal name 
 * and the password. The TGT will be obtained using the authentication 
 * exchange with the KDC.
 * The Subject will be populated with the TGT.
 *<ul>
 * <p> <code>useKeyTab</code> = true 
 * <code>keyTab</code>=< keytab filename >
 * <code>principal</code>= < principal name > 
 * <code>storeKey</code>=true;
 *</ul>
 * <p>  The key for the principal will be retrieved from the keytab.
 * If the key is not available in the keytab the user will be prompted
 * for the principal's password. The Subject will be populated
 * with the principal's key either from the keytab or derived from the
 * password entered.
 * <ul>
 * <p> <code>useKeyTab</code> = true 
 * <code>keyTab</code>=< keytabname >
 * <code>storeKey</code>=true
 * <code>doNotPrompt</code>=true;
 *</ul>
 * <p>The user will be prompted for the service principal name. 
 * If the principal's
 * longterm key is available in the keytab , it will be added to the
 * Subject's private credentials. An authentication exchange will be 
 * attempted with the principal name and the key from the Keytab. 
 * If successful the TGT will be added to the
 * Subject's private credentials set. Otherwise the authentication will
 * fail.
 *<ul>
 * <p><code>useKeyTab</code> = true
 * <code>keyTab</code>=< file name > <code>storeKey</code>=true
 * <code>principal</code>= < principal name > 
 * <code>useTicketCache</code>=true
 * <code>ticketCache</code>=< file name >;
 *</ul>
 * <p>The principal's key will be retrieved from the keytab and added
 * to the <code>Subject</code>'s private credentials. If the key 
 * is not available, the
 * user will be prompted for the password; the key derived from the password
 * will be added to the Subject's private credentials set. The
 * client's TGT will be retrieved from the ticket cache and added to the
 * <code>Subject</code>'s private credentials. If the TGT is not available  
 * in the ticket cache, it will be obtained using the authentication
 * exchange and added to the Subject's private credentials.
 * <ul>
 * <p><code>isInitiator</code> = false 
 *</ul>
 * <p>Configured to act as acceptor only, credentials are not acquired
 * via AS exchange. For acceptors only, set this value to false. 
 * For initiators, do not set this value to false.
 * <ul>
 * <p><code>isInitiator</code> = true 
 *</ul>
 * <p>Configured to act as initiator, credentials are acquired
 * via AS exchange. For initiators, set this value to true, or leave this
 * option unset, in which case default value (true) will be used.
 *
 * @version 1.18, 01/11/00
 * @author Ram Marti
 */

public class Krb5LoginModule implements LoginModule {

    // initial state
    private Subject subject;
    private CallbackHandler callbackHandler;
    private Map sharedState;
    private Map options;

    // configurable option
    private boolean debug = false;
    private boolean storeKey = false;
    private boolean doNotPrompt = false;
    private boolean useTicketCache = false;
    private boolean useKeyTab = false;
    private String ticketCacheName = null;
    private String keyTabName = null;
    private String princName = null;

    private boolean useFirstPass = false;
    private boolean tryFirstPass = false;
    private boolean storePass = false;
    private boolean clearPass = false;
    private boolean refreshKrb5Config = false;
    private boolean renewTGT = false;

    // specify if initiator.
    // perform authentication exchange if initiator
    private boolean isInitiator = true;

    // the authentication status
    private boolean succeeded = false;
    private boolean commitSucceeded = false;
    private String username;
    private EncryptionKey[] encKeys = null;
    private Credentials cred = null;

    private PrincipalName principal = null;
    private KerberosPrincipal kerbClientPrinc = null;
    private KerberosTicket kerbTicket = null;
    private KerberosKey[] kerbKeys = null;
    private StringBuffer krb5PrincName = null;
    private char[] password = null;

    private static final String NAME = "javax.security.auth.login.name";
    private static final String PWD = "javax.security.auth.login.password";
    static final java.util.ResourceBundle rb =
        java.util.ResourceBundle.getBundle("sun.security.util.AuthResources");

    /**
     * Initialize this <code>LoginModule</code>.
     *
     * <p>
     * @param subject the <code>Subject</code> to be authenticated. <p>
     *
     * @param callbackHandler a <code>CallbackHandler</code> for 
     *                  communication with the end user (prompting for
     *                  usernames and passwords, for example). <p>
     *
     * @param sharedState shared <code>LoginModule</code> state. <p>
     *
     * @param options options specified in the login
     *          <code>Configuration</code> for this particular
     *          <code>LoginModule</code>.
     */

    public void initialize(Subject subject, 
               CallbackHandler callbackHandler,
               Map<String, ?> sharedState,
               Map<String, ?> options) {
 
    this.subject = subject;
    this.callbackHandler = callbackHandler;
    this.sharedState = sharedState;
    this.options = options;

    // initialize any configured options

    debug = "true".equalsIgnoreCase((String)options.get("debug"));
    storeKey = "true".equalsIgnoreCase((String)options.get("storeKey"));
    doNotPrompt = "true".equalsIgnoreCase((String)options.get
                          ("doNotPrompt"));
    useTicketCache = "true".equalsIgnoreCase((String)options.get
                         ("useTicketCache"));
    useKeyTab = "true".equalsIgnoreCase((String)options.get("useKeyTab"));
    ticketCacheName = (String)options.get("ticketCache");
    keyTabName = (String)options.get("keyTab");
    princName = (String)options.get("principal");
    refreshKrb5Config =
        "true".equalsIgnoreCase((String)options.get("refreshKrb5Config"));
    renewTGT =
        "true".equalsIgnoreCase((String)options.get("renewTGT"));

    // check isInitiator value
    String isInitiatorValue = ((String)options.get("isInitiator"));
    if (isInitiatorValue == null) {
        // use default, if value not set
    } else {
        isInitiator = "true".equalsIgnoreCase(isInitiatorValue);
    }

    tryFirstPass =
        "true".equalsIgnoreCase
        ((String)options.get("tryFirstPass"));
    useFirstPass =
        "true".equalsIgnoreCase
        ((String)options.get("useFirstPass"));
    storePass =
        "true".equalsIgnoreCase((String)options.get("storePass"));
    clearPass =
        "true".equalsIgnoreCase((String)options.get("clearPass"));
    if (debug) {
        System.out.print("Debug is  " + debug  
                 + " storeKey " + storeKey 
                 + " useTicketCache " + useTicketCache
                 + " useKeyTab " + useKeyTab
                 + " doNotPrompt " + doNotPrompt
                 + " ticketCache is " + ticketCacheName
                 + " isInitiator " + isInitiator
                 + " KeyTab is " + keyTabName
                 + " refreshKrb5Config is " + refreshKrb5Config
                     + " principal is " + princName
                 + " tryFirstPass is " + tryFirstPass 
                 + " useFirstPass is " + useFirstPass
                 + " storePass is " + storePass
                 + " clearPass is " + clearPass + "\n");
    }
    }
    

    /**
     * Authenticate the user 
     *
     * <p>
     *
     * @return true in all cases since this <code>LoginModule</code>
     *      should not be ignored.
     *
     * @exception FailedLoginException if the authentication fails. <p>
     *
     * @exception LoginException if this <code>LoginModule</code>
     *      is unable to perform the authentication.
     */
    public boolean login() throws LoginException {

    int len;    
    validateConfiguration();
    if (refreshKrb5Config) {
        try {
        if (debug) {
            System.out.println("Refreshing Kerberos configuration");
        }
            sun.security.krb5.Config.refresh();
        } catch (KrbException ke) {
            LoginException le = new LoginException(ke.getMessage());
            le.initCause(ke);
            throw le;
        }
    }
    String principalProperty = System.getProperty
        ("sun.security.krb5.principal"); 
    if (principalProperty != null) {
        krb5PrincName = new StringBuffer(principalProperty);
    } else {
        if (princName != null) {
        krb5PrincName = new StringBuffer(princName);
        }
        }
    
    if (tryFirstPass) {
        try {
        attemptAuthentication(true);    
        if (debug)
            System.out.println("\t\t[Krb5LoginModule] " +
                       "authentication succeeded");
        succeeded = true;
        cleanState();
        return true;
        } catch (LoginException le) {
        // authentication failed -- try again below by prompting
        cleanState();
        if (debug) {
            System.out.println("\t\t[Krb5LoginModule] " +
                       "tryFirstPass failed with:" +
                       le.getMessage());
        }
        } 
    } else if (useFirstPass) {
        try {
        attemptAuthentication(true);
        succeeded = true;
        cleanState();
        return true;
        } catch (LoginException e) {
        // authentication failed -- clean out state
        if (debug) {
            System.out.println("\t\t[Krb5LoginModule] " +
                       "authentication failed \n" +
                       e.getMessage());
        }
        succeeded = false;
        cleanState();
        throw e;
        } 
    }
    
    // attempt the authentication by getting the username and pwd 
    // by prompting or configuration i.e. not from shared state
    
    try {
        attemptAuthentication(false);
        succeeded = true;
        cleanState();
        return true;
    } catch (LoginException e) {
        // authentication failed -- clean out state
        if (debug) {
        System.out.println("\t\t[Krb5LoginModule] " +
                   "authentication failed \n" +
                   e.getMessage());
        }
        succeeded = false;
        cleanState();
        throw e;
    }
    }
    /** 
     * process the configuration options
     * Get the TGT either out of
     * cache or from the KDC using the password entered
     * Check the  permission before getting the TGT
     */

    private void attemptAuthentication(boolean getPasswdFromSharedState)
    throws LoginException {
    
    /* 
     * Check the creds cache to see whether 
     * we have TGT for this client principal
     */
    if (krb5PrincName != null) {
        try {
            principal = new PrincipalName
            (krb5PrincName.toString(),
             PrincipalName.KRB_NT_PRINCIPAL);
        } catch (KrbException e) {
        LoginException le = new LoginException(e.getMessage());
        le.initCause(e);
        throw le;
        }
    }

    try { 
        if (useTicketCache) {
        // ticketCacheName == null implies the default cache
        if (debug)
            System.out.println("Acquire TGT from Cache");
        cred  = Credentials.acquireTGTFromCache
            (principal, ticketCacheName);

        if (cred != null) {
            // check to renew credentials
            if (!isCurrent(cred)) {
            if (renewTGT) {
                cred = renewCredentials(cred);
            } else {
                // credentials have expired
                cred = null;
                if (debug)
                System.out.println("Credentials are" +
                        " no longer valid");
            }
            }
        }

        if (cred != null) {
           // get the principal name from the ticket cache
           if (principal == null) { 
            principal = cred.getClient();
           }
        }
        if (debug) {
            System.out.println("Principal is " + principal);
            if (cred == null) {
            System.out.println
                ("null credentials from Ticket Cache");
            }
        }
        }            

        // cred = null indicates that we didn't get the creds
        // from the cache or useTicketCache was false
        
        if (cred == null) {
        // We need the principal name whether we use keytab
        // or AS Exchange
        if (principal == null) {
            promptForName(getPasswdFromSharedState);
            principal = new PrincipalName
            (krb5PrincName.toString(),
             PrincipalName.KRB_NT_PRINCIPAL);
        }
        if (useKeyTab) {
            encKeys = 
            EncryptionKey.acquireSecretKeys(principal, keyTabName);

            if (debug) {
            if (encKeys != null)
                System.out.println
                ("principal's key obtained from the keytab");
            else
                System.out.println
                ("Key for the principal " + 
                 principal  + 
                 " not available in " + 
                 ((keyTabName == null) ? 
                  "default key tab" : keyTabName));
            }
            
        }   
        // We can't get the key from the keytab so prompt    
        if (encKeys == null) {  
            promptForPass(getPasswdFromSharedState);

            encKeys = EncryptionKey.acquireSecretKeys(
            password, principal.getSalt());

            if (isInitiator) {
            if (debug)
                System.out.println("Acquire TGT using AS Exchange");
            cred = Credentials.acquireTGT(principal, 
                        encKeys, password);
            // update keys after pre-auth
            encKeys = EncryptionKey.acquireSecretKeys(password, 
                            principal.getSalt());
            }
        } else {
            if (isInitiator) {
            if (debug)
                System.out.println("Acquire TGT using AS Exchange");
            cred = Credentials.acquireTGT(principal, 
                        encKeys, password);
            }
        }

        // Get the TGT using AS Exchange
        if (debug) {
            System.out.println("principal is " + principal);
            HexDumpEncoder hd = new HexDumpEncoder();   
            for (int i = 0; i < encKeys.length; i++) {
            System.out.println("EncryptionKey: keyType=" + 
                encKeys[i].getEType() + " keyBytes (hex dump)=" +
                            hd.encode(encKeys[i].getBytes()));
            }
        }

        // we should hava a non-null cred
        if (isInitiator && (cred == null)) {
            throw new LoginException 
            ("TGT Can not be obtained from the KDC ");
        }

        }
    } catch (KrbException e) {
        LoginException le = new LoginException(e.getMessage());
        le.initCause(e);
        throw le;
    } catch (IOException ioe) {
        LoginException ie = new LoginException(ioe.getMessage());
        ie.initCause(ioe);
        throw ie;
    }
    }
    
    private void promptForName(boolean getPasswdFromSharedState)
    throws LoginException {
    krb5PrincName = new StringBuffer("");
    if (getPasswdFromSharedState) {
        // use the name saved by the first module in the stack
        username = (String)sharedState.get(NAME);
        if (debug) {
        System.out.println
            ("username from shared state is " + username + "\n");
        }
        if (username == null) {
        System.out.println
            ("username from shared state is null\n");
        throw new LoginException
            ("Username can not be obtained from sharedstate ");
        }
        if (debug) {
        System.out.println
            ("username from shared state is " + username + "\n");
        }
        if (username != null && username.length() > 0) {
        krb5PrincName.insert(0, username);
        return;
        }
    }
   
    if (doNotPrompt) {
        throw new LoginException
        ("Unable to obtain Princpal Name for authentication ");
    } else {
        if (callbackHandler == null)
        throw new LoginException("No CallbackHandler "
                     + "available "
                     + "to garner authentication " 
                     + "information from the user");
        try {
        String defUsername = System.getProperty("user.name");
        
        Callback[] callbacks = new Callback[1];
        MessageFormat form = new MessageFormat(
                       rb.getString(
                       "Kerberos username [[defUsername]]: "));
            Object[] source =  {defUsername};
        callbacks[0] = new NameCallback(form.format(source));
        callbackHandler.handle(callbacks);
        username = ((NameCallback)callbacks[0]).getName();
        if (username == null || username.length() == 0)
            username = defUsername;
        krb5PrincName.insert(0, username);
        
        } catch (java.io.IOException ioe) {
        throw new LoginException(ioe.getMessage());
        } catch (UnsupportedCallbackException uce) {
        throw new LoginException
            (uce.getMessage()
             +" not available to garner " 
             +" authentication information " 
             +" from the user");
        }
    }
    }
    
    private void promptForPass(boolean getPasswdFromSharedState) 
    throws LoginException {

    if (getPasswdFromSharedState) {
        // use the password saved by the first module in the stack
        password = (char[])sharedState.get(PWD);
        if (password == null) {
        if (debug) {
            System.out.println
            ("Password from shared state is null");
        }
        throw new LoginException
            ("Password can not be obtained from sharedstate ");
        }
        if (debug) {
        System.out.println
            ("password is " + new String(password));
        }
        return;
    }
    if (doNotPrompt) {
        throw new LoginException
        ("Unable to obtain password from user\n");
    } else {
        if (callbackHandler == null)
        throw new LoginException("No CallbackHandler "
                     + "available "
                     + "to garner authentication " 
                     + "information from the user");
        try {
        Callback[] callbacks = new Callback[1];
        String userName = krb5PrincName.toString();
        MessageFormat form = new MessageFormat(
                     rb.getString(
                     "Kerberos password for [username]: "));
            Object[] source = {userName};
        callbacks[0] = new PasswordCallback(
                            form.format(source),
                            false);
        callbackHandler.handle(callbacks);
        char[] tmpPassword = ((PasswordCallback)
                      callbacks[0]).getPassword();
        if (tmpPassword == null) {
            // treat a NULL password as an empty password
            tmpPassword = new char[0];
        }
        password = new char[tmpPassword.length];
        System.arraycopy(tmpPassword, 0,
                 password, 0, tmpPassword.length);
        ((PasswordCallback)callbacks[0]).clearPassword();
        

        // clear tmpPassword
        for (int i = 0; i < tmpPassword.length; i++)
            tmpPassword[i] = ' ';
        tmpPassword = null;
        if (debug) {
            System.out.println("\t\t[Krb5LoginModule] " +
                       "user entered username: " +
                       krb5PrincName);
            System.out.println();
        }
        } catch (java.io.IOException ioe) {
        throw new LoginException(ioe.getMessage());
        } catch (UnsupportedCallbackException uce) {
        throw new LoginException(uce.getMessage()
                     +" not available to garner " 
                     +" authentication information " 
                     + "from the user");
        }
    }   
    }

    private void validateConfiguration() throws LoginException {
    if (doNotPrompt && !useTicketCache && !useKeyTab)
        throw new LoginException
        ("Configuration Error" 
         + " - either doNotPrompt should be "
         + " false or useTicketCache/useKeyTab "
         + " should be true");
    if (ticketCacheName != null && !useTicketCache)
        throw new LoginException
        ("Configuration Error " 
         + " - useTicketCache should be set "
         + "to true to use the ticket cache" 
         + ticketCacheName);
    if (keyTabName != null & !useKeyTab)
        throw new LoginException
        ("Configuration Error - useKeyTab should be set to true "
         + "to use the keytab" + keyTabName);
    if (storeKey && doNotPrompt && !useKeyTab) 
        throw new LoginException
        ("Configuration Error - either doNotPrompt "
         + "should be set to false or "
         + "useKeyTab must be set to true for storeKey option");
    if (renewTGT && !useTicketCache)
        throw new LoginException
        ("Configuration Error" 
         + " - either useTicketCache should be "
         + " true or renewTGT should be false");
    }
  
    private boolean isCurrent(Credentials creds)
    {
    Date endTime = creds.getEndTime();
    if (endTime != null) {
        return (System.currentTimeMillis() <= endTime.getTime());
    }
    return true;
    }

    private Credentials renewCredentials(Credentials creds) 
    {
    Credentials lcreds;
    try {
        if (!creds.isRenewable())
        throw new RefreshFailedException("This ticket" +
                " is not renewable");
        if (System.currentTimeMillis() > cred.getRenewTill().getTime())
        throw new RefreshFailedException("This ticket is past "
                                             + "its last renewal time.");
        lcreds = creds.renew();
        if (debug)
        System.out.println("Renewed Kerberos Ticket");
    } catch (Exception e) {
        lcreds = null;
        if (debug)
        System.out.println("Ticket could not be renewed : "
                + e.getMessage());
    }
    return lcreds;
    }

    /**
     * <p> This method is called if the LoginContext's
     * overall authentication succeeded
     * (the relevant REQUIRED, REQUISITE, SUFFICIENT and OPTIONAL
     * LoginModules succeeded).
     *
     * <p> If this LoginModule's own authentication attempt
     * succeeded (checked by retrieving the private state saved by the
     * <code>login</code> method), then this method associates a
     * <code>Krb5Principal</code>
     * with the <code>Subject</code> located in the
     * <code>LoginModule</code>. It adds Kerberos Credentials to the
     *  the Subject's private credentials set. If this LoginModule's own
     * authentication attempted failed, then this method removes
     * any state that was originally saved.
     *
     * <p>
     *
     * @exception LoginException if the commit fails.
     *
     * @return true if this LoginModule's own login and commit
     *      attempts succeeded, or false otherwise.
     */

    public boolean commit() throws LoginException {

    /*
     * Let us add the Krb5 Creds to the Subject's 
     * private credentials. The credentials are of type
     * KerberosKey or KerberosTicket
     */
    if (succeeded == false) {
        return false;
    } else {

        if (isInitiator && (cred == null)) {
        succeeded = false;
        throw new LoginException("Null Client Credential");
        }

        if (subject.isReadOnly()) {
            cleanKerberosCred();
        throw new LoginException("Subject is Readonly");
        }

        /*
         * Add the Principal (authenticated identity)
         * to the Subject's principal set and
         * add the credentials (TGT or Service key) to the
         * Subject's private credentials
         */

        Set privCredSet =  subject.getPrivateCredentials();
        Set princSet  = subject.getPrincipals();
        kerbClientPrinc = new KerberosPrincipal(principal.getName());
    
        // create Kerberos Ticket 
        if (isInitiator) {
        kerbTicket = Krb5Util.credsToTicket(cred);
        }

        if (storeKey) {
        if (encKeys == null || encKeys.length <= 0) {
            succeeded = false;
            throw new LoginException("Null Server Key ");
        }

        kerbKeys = new KerberosKey[encKeys.length];
        for (int i = 0; i < encKeys.length; i ++) {
                Integer temp = encKeys[i].getKeyVersionNumber();
            kerbKeys[i] = new KerberosKey(kerbClientPrinc,
                      encKeys[i].getBytes(),
                      encKeys[i].getEType(),
                      (temp == null?
                      0: temp.intValue()));
                }
        
        }
        // Let us add the kerbClientPrinc,kerbTicket and kerbKey (if
        // storeKey is true)
        if (!princSet.contains(kerbClientPrinc))
        princSet.add(kerbClientPrinc);

        // add the TGT
        if (kerbTicket != null) {
        if (!privCredSet.contains(kerbTicket))  
            privCredSet.add(kerbTicket);
        }

        if (storeKey) {
        for (int i = 0; i < kerbKeys.length; i++) {
            if (!privCredSet.contains(kerbKeys[i])) {   
                privCredSet.add(kerbKeys[i]);
            }
            encKeys[i].destroy();
            encKeys[i] = null;
            if (debug) {
                System.out.println("Added server's key"
                    + kerbKeys[i]);         
                System.out.println("\t\t[Krb5LoginModule] " +
                       "added Krb5Principal  " + 
                       kerbClientPrinc.toString()
                       + " to Subject");
            }           
        }
        }
    }
    commitSucceeded = true;
    if (debug)
        System.out.println("Commit Succeeded \n");
    return true;
    }
    
    /**
     * <p> This method is called if the LoginContext's
     * overall authentication failed.
     * (the relevant REQUIRED, REQUISITE, SUFFICIENT and OPTIONAL 
     * LoginModules did not succeed).
     *
     * <p> If this LoginModule's own authentication attempt
     * succeeded (checked by retrieving the private state saved by the
     * <code>login</code> and <code>commit</code> methods),
     * then this method cleans up any state that was originally saved.
     *
     * <p>
     *
     * @exception LoginException if the abort fails.
     *
     * @return false if this LoginModule's own login and/or commit attempts
     *      failed, and true otherwise.
     */

    public boolean abort() throws LoginException {
    if (succeeded == false) {
        return false;
    } else if (succeeded == true && commitSucceeded == false) {
        // login succeeded but overall authentication failed
        succeeded = false;
        cleanKerberosCred();
    } else {
        // overall authentication succeeded and commit succeeded,
        // but someone else's commit failed
        logout();
    }
    return true;
    }
    
    /**
     * Logout the user.
     *
     * <p> This method removes the <code>Krb5Principal</code>
     * that was added by the <code>commit</code> method.
     *
     * <p>
     *
     * @exception LoginException if the logout fails.
     *
     * @return true in all cases since this <code>LoginModule</code>
     *          should not be ignored.
     */
    public boolean logout() throws LoginException {

        if (debug) {
            System.out.println("\t\t[Krb5LoginModule]: " +
                "Entering logout");
        }

        if (subject.isReadOnly()) {
        cleanKerberosCred();
            throw new LoginException("Subject is Readonly");
        }
    
    subject.getPrincipals().remove(kerbClientPrinc);
       // Let us remove all Kerberos credentials stored in the Subject 
    Iterator it = subject.getPrivateCredentials().iterator();
    while (it.hasNext()) {
        Object o = it.next();
        if (o instanceof KerberosTicket ||
        o instanceof KerberosKey) {
        it.remove();
        }
    }
    // clean the kerberos ticket and keys
    cleanKerberosCred();

    succeeded = false;
    commitSucceeded = false;
    if (debug) {
            System.out.println("\t\t[Krb5LoginModule]: " +
                   "logged out Subject");
        }
    return true;
    }

    /**
     * Clean Kerberos credentials
     */ 
    private void cleanKerberosCred() throws LoginException {
    // Clean the ticket and server key
    try {
        if (kerbTicket != null)
        kerbTicket.destroy();
        if (kerbKeys != null) {
            for (int i = 0; i < kerbKeys.length; i++) {
            kerbKeys[i].destroy();
        }
            }
    } catch (DestroyFailedException e) {
        throw new LoginException
        ("Destroy Failed on Kerberos Private Credentials");
    }
    kerbTicket = null;
    kerbKeys = null;
    kerbClientPrinc = null;
    }

    /**
     * Clean out the state 
     */
    private void cleanState() {
       
    // save input as shared state only if
    // authentication succeeded
    if (succeeded) {
        if (storePass &&
        !sharedState.containsKey(NAME) &&
        !sharedState.containsKey(PWD)) {
        sharedState.put(NAME, username);
        sharedState.put(PWD, password);
        }
    }
    username = null;
    password = null;
    if (krb5PrincName != null && krb5PrincName.length() != 0)
        krb5PrincName.delete(0, krb5PrincName.length());
    krb5PrincName = null;
    if (clearPass) {
        sharedState.remove(NAME);
        sharedState.remove(PWD);
    }
    }
}