/*
 * @(#)KerberosTicket.java	1.16 04/06/02
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
  
package javax.security.auth.kerberos;

import java.io.*;
import java.util.Date;
import java.util.Arrays;
import java.net.InetAddress;
import javax.crypto.SecretKey;
import javax.security.auth.Refreshable;
import javax.security.auth.Destroyable;
import javax.security.auth.RefreshFailedException;
import javax.security.auth.DestroyFailedException;
import sun.misc.HexDumpEncoder;
import sun.security.krb5.EncryptionKey;
import sun.security.krb5.Asn1Exception;
import sun.security.util.*;

/**
 * This class encapsulates a Kerberos ticket and associated
 * information as viewed from the client's point of view. It captures all
 * information that the Key Distribution Center (KDC) sends to the client
 * in the reply message KDC-REP defined in the Kerberos Protocol
 * Specification (<a href=http://www.ietf.org/rfc/rfc1510.txt>RFC 1510</a>).
 * <p>
 * All Kerberos JAAS login modules that authenticate a user to a KDC should
 * use this class. Where available, the login module might even read this 
 * information from a ticket cache in the operating system instead of
 * directly communicating with the KDC. During the commit phase of the JAAS
 * authentication process, the JAAS login module should instantiate this
 * class and store the instance in the private credential set of a
 * {@link javax.security.auth.Subject Subject}.<p>
 *
 * It might be necessary for the application to be granted a
 * {@link javax.security.auth.PrivateCredentialPermission 
 * PrivateCredentialPermission} if it needs to access a KerberosTicket
 * instance from a Subject. This permission is not needed when the
 * application depends on the default JGSS Kerberos mechanism to access the
 * KerberosTicket. In that case, however, the application will need an
 * appropriate
 * {@link javax.security.auth.kerberos.ServicePermission ServicePermission}.
 * <p>
 * Note that this class is applicable to both ticket granting tickets and
 * other regular service tickets. A ticket granting ticket is just a
 * special case of a more generalized service ticket.
 *
 * @see javax.security.auth.Subject
 * @see javax.security.auth.PrivateCredentialPermission
 * @see javax.security.auth.login.LoginContext
 * @see org.ietf.jgss.GSSCredential
 * @see org.ietf.jgss.GSSManager
 * 
 * @author Mayank Upadhyay
 * @version 1.16, 06/02/04
 * @since 1.4
 */
public class KerberosTicket implements Destroyable, Refreshable,
	 java.io.Serializable {

    private static final long serialVersionUID = 7395334370157380539L;

    // TBD: Make these flag indices public
    private static final int FORWARDABLE_TICKET_FLAG = 1;
    private static final int FORWARDED_TICKET_FLAG   = 2;
    private static final int PROXIABLE_TICKET_FLAG   = 3;
    private static final int PROXY_TICKET_FLAG       = 4;
    private static final int POSTDATED_TICKET_FLAG   = 6;
    private static final int RENEWABLE_TICKET_FLAG   = 8;
    private static final int INITIAL_TICKET_FLAG     = 9;

    private static final int NUM_FLAGS = 32;

    /**
     * 
     * ASN.1 DER Encoding of the Ticket as defined in the 
     * Kerberos Protocol Specification RFC1510.
     *
     * @serial
     */

    private byte[] asn1Encoding;

    /**
     *<code>KeyImpl</code> is serialized by writing out the ASN1 Encoded bytes 
     * of the encryption key. The ASN1 encoding is defined in RFC1510 and as
     * follows:
     * <pre>		
     *			EncryptionKey ::=   SEQUENCE {
     *				keytype[0]    INTEGER,
     *				keyvalue[1]   OCTET STRING    	
     *				}
     * </pre>
     *
     * @serial
     */

    private KeyImpl sessionKey;

    /**
     * 
     * Ticket Flags as defined in the Kerberos Protocol Specification RFC1510.
     *
     * @serial
     */

    private boolean[] flags;

    /**
     * 
     * Time of initial authentication 
     *
     * @serial
     */

    private Date authTime;

    /**
     * 
     * Time after which the ticket is valid.
     * @serial
     */
    private Date startTime;

    /**
     * 
     * Time after which the ticket will not be honored. (its expiration time).
     *
     * @serial
     */

    private Date endTime;

    /**
     * 
     * For renewable Tickets it indicates the maximum endtime that may be 
     * included in a renewal. It can be thought of as the absolute expiration 
     * time for the ticket, including all renewals. This field may be null
     * for tickets that are not renewable.
     *
     * @serial
     */

    private Date renewTill;

    /**
     * 
     * Client that owns the service ticket
     * 
     * @serial
     */

    private KerberosPrincipal client;

    /**
     * 
     * The service for which the ticket was issued.
     * 
     * @serial
     */

    private KerberosPrincipal server;
	
    /**
     * 
     * The addresses from where the ticket may be used by the client. 
     * This field may be null when the ticket is usable from any address.
     *
     * @serial
     */


    private InetAddress[] clientAddresses;

    private transient boolean destroyed = false;

    /**
     * Constructs a KerberosTicket using credentials information that a
     * client either receives from a KDC or reads from a cache.
     *
     * @param asn1Encoding the ASN.1 encoding of the ticket as defined by
     * the Kerberos protocol specification.
     * @param client the client that owns this service
     * ticket
     * @param server the service that this ticket is for
     * @param sessionKey the raw bytes for the session key that must be
     * used to encrypt the authenticator that will be sent to the server
     * @param keyType the key type for the session key as defined by the
     * Kerberos protocol specification.
     * @param flags the ticket flags. Each element in this array indicates
     * the value for the corresponding bit in the ASN.1 BitString that
     * represents the ticket flags. If the number of elements in this array 
     * is less than the number of flags used by the Kerberos protocol,
     * then the missing flags will be filled in with false.
     * @param authTime the time of initial authentication for the client
     * @param startTime the time after which the ticket will be valid. This 
     * may be null in which case the value of authTime is treated as the
     * startTime.
     * @param endTime the time after which the ticket will no longer be
     * valid
     * @param renewTill an absolute expiration time for the ticket,
     * including all renewal that might be possible. This field may be null 
     * for tickets that are not renewable.
     * @param clientAddresses the addresses from where the ticket may be
     * used by the client. This field may be null when the ticket is usable 
     * from any address.
     */
    public KerberosTicket(byte[] asn1Encoding, 
			 KerberosPrincipal client,
			 KerberosPrincipal server,
			 byte[] sessionKey,
			 int keyType,
			 boolean[] flags,
			 Date authTime,
			 Date startTime,
			 Date endTime,
			 Date renewTill,
			 InetAddress[] clientAddresses) {
       
	init(asn1Encoding, client, server, sessionKey, keyType, flags,
	    authTime, startTime, endTime, renewTill, clientAddresses);
    }
    
    private void init(byte[] asn1Encoding, 
			 KerberosPrincipal client,
			 KerberosPrincipal server,
			 byte[] sessionKey,
			 int keyType,
			 boolean[] flags,
			 Date authTime,
			 Date startTime,
			 Date endTime,
			 Date renewTill,
			 InetAddress[] clientAddresses) {

	if (asn1Encoding == null)
	   throw new IllegalArgumentException("ASN.1 encoding of ticket"
					      + " cannot be null");
	this.asn1Encoding = asn1Encoding.clone();

	if (client == null)
	   throw new IllegalArgumentException("Client name in ticket"
					      + " cannot be null");
	this.client = client;

	if (server == null)
	   throw new IllegalArgumentException("Server name in ticket"
					      + " cannot be null");
	this.server = server;

	if (sessionKey == null)
	   throw new IllegalArgumentException("Session key for ticket"
					      + " cannot be null");
	this.sessionKey = new KeyImpl(sessionKey, keyType);

	if (flags != null) {
	   if (flags.length >= NUM_FLAGS)
		this.flags = (boolean[]) flags.clone();
	   else {
		this.flags = new boolean[NUM_FLAGS];
		// Fill in whatever we have
		for (int i = 0; i < flags.length; i++)
		    this.flags[i] = flags[i];
	   }
	} else
	   this.flags = new boolean[NUM_FLAGS];

	if (this.flags[RENEWABLE_TICKET_FLAG]) {
	   if (renewTill == null)
		throw new IllegalArgumentException("The renewable period "
		       + "end time cannot be null for renewable tickets.");

	   this.renewTill = renewTill;
	}

	if (authTime == null)
	   throw new IllegalArgumentException("Authentication time of ticket"
					      + " cannot be null");
	this.authTime = authTime;

	this.startTime = (startTime != null? startTime: authTime);

	if (endTime == null)
	   throw new IllegalArgumentException("End time for ticket validity"
					      + " cannot be null");
	this.endTime = endTime;

	if (clientAddresses != null)
	   this.clientAddresses = (InetAddress[]) clientAddresses.clone();
    }

    /**
     * Returns the client principal associated with this ticket.
     *
     * @return the client principal.
     */
    public final KerberosPrincipal getClient() {
	return client;
    }
    
    /**
     * Returns the service principal associated with this ticket.
     *
     * @return the service principal.
     */
    public final KerberosPrincipal getServer() {
	return server;
    }
    
    /**
     * Returns the session key associated with this ticket.
     *
     * @return the session key.
     */
    public final SecretKey getSessionKey() {
	if (destroyed)
	    throw new IllegalStateException("This ticket is no longer valid");
	return sessionKey;
    }

    /**
     * Returns the key type of the session key associated with this
     * ticket as defined by the Kerberos Protocol Specification.
     *
     * @return the key type of the session key associated with this
     * ticket.
     *
     * @see #getSessionKey()
     */
    public final int getSessionKeyType() {
	if (destroyed)
	    throw new IllegalStateException("This ticket is no longer valid");
	return sessionKey.getKeyType();
    }

    /** 
     * Determines if this ticket is forwardable.
     *
     * @return true if this ticket is forwardable, false if not.
     */
    public final boolean isForwardable() {
	return flags[FORWARDABLE_TICKET_FLAG];
    }

    /** 
     * Determines if this ticket had been forwarded or was issued based on
     * authentication involving a forwarded ticket-granting ticket.
     *
     * @return true if this ticket had been forwarded or was issued based on
     * authentication involving a forwarded ticket-granting ticket,
     * false otherwise.
     */
    public final boolean isForwarded() {
	return flags[FORWARDED_TICKET_FLAG];
    }

    /** 
     * Determines if this ticket is proxiable.
     *
     * @return true if this ticket is proxiable, false if not.
     */
    public final boolean isProxiable() {
	return flags[PROXIABLE_TICKET_FLAG];
    }

    /** 
     * Determines is this ticket is a proxy-ticket.
     *
     * @return true if this ticket is a proxy-ticket, false if not.
     */
    public final boolean isProxy() {
	return flags[PROXY_TICKET_FLAG];
    }


    /** 
     * Determines is this ticket is post-dated.
     *
     * @return true if this ticket is post-dated, false if not.
     */
    public final boolean isPostdated() {
	return flags[POSTDATED_TICKET_FLAG];
    }

    /** 
     * Determines is this ticket is renewable. If so, the {@link #refresh() 
     * refresh} method can be called, assuming the validity period for
     * renewing is not already over.
     *
     * @return true if this ticket is renewable, false if not.
     */
    public final boolean isRenewable() {
	return flags[RENEWABLE_TICKET_FLAG];
    }

    /** 
     * Determines if this ticket was issued using the Kerberos AS-Exchange
     * protocol, and not issued based on some ticket-granting ticket.
     *
     * @return true if this ticket was issued using the Kerberos AS-Exchange
     * protocol, false if not.
     */
    public final boolean isInitial() {
	return flags[INITIAL_TICKET_FLAG];
    }

    /**
     * Returns the flags associated with this ticket. Each element in the
     * returned array indicates the value for the corresponding bit in the
     * ASN.1 BitString that represents the ticket flags.
     *
     * @return the flags associated with this ticket.
     */
    public final boolean[]  getFlags() {
	return (flags == null? null: (boolean[]) flags.clone());
    }

    /**
     * Returns the time that the client was authenticated.
     *
     * @return the time that the client was authenticated.
     */
    public final java.util.Date getAuthTime() {
	return (authTime == null) ? null : new Date(authTime.getTime());
    }

    /**
     * Returns the start time for this ticket's validity period.
     *
     * @return the start time for this ticket's validity period.
     */
    public final java.util.Date getStartTime() {
	return (startTime == null) ? null : new Date(startTime.getTime());
    }

    /**
     * Returns the expiration time for this ticket's validity period.
     *
     * @return the expiration time for this ticket's validity period.
     */
    public final java.util.Date getEndTime() {
	return (endTime == null) ? null : new Date(endTime.getTime());
    }

    /**
     * Returns the latest expiration time for this ticket, including all
     * renewals. This will return a null value for non-renewable tickets.
     *
     * @return the latest expiration time for this ticket.
     */
    public final java.util.Date getRenewTill() {
	return (renewTill == null) ? null: new Date(renewTill.getTime());
    }
    
    /**
     * Returns a list of addresses from where the ticket can be used.
     * 
     * @return ths list of addresses or null, if the field was not
     * provided.
     */
    public final java.net.InetAddress[] getClientAddresses() {
	return (clientAddresses == null? 
		null: (InetAddress[]) clientAddresses.clone());
    }

    /**
     * Returns an ASN.1 encoding of the entire ticket.
     *
     * @return an ASN.1 encoding of the entire ticket.
     */
    public final byte[] getEncoded() {
	if (destroyed)
	    throw new IllegalStateException("This ticket is no longer valid");
	return (byte[]) asn1Encoding.clone();
    }

    /** Determines if this ticket is still current.  */
    public boolean isCurrent() {
	return (System.currentTimeMillis() <= getEndTime().getTime());
    }

    /**
     * Extends the validity period of this ticket. The ticket will contain
     * a new session key if the refresh operation succeeds. The refresh
     * operation will fail if the ticket is not renewable or the latest
     * allowable renew time has passed. Any other error returned by the
     * KDC will also cause this method to fail.
     *
     * Note: This method is not synchronized with the the accessor
     * methods of this object. Hence callers need to be aware of multiple
     * threads that might access this and try to renew it at the same
     * time.
     *
     * @throws RefreshFailedException if the ticket is not renewable, or
     * the latest allowable renew time has passed, or the KDC returns some
     * error.
     *
     * @see #isRenewable()
     * @see #getRenewTill()
     */
    public void refresh() throws RefreshFailedException {

	if (destroyed)
	    throw new RefreshFailedException("A destroyed ticket "
					     + "cannot be renewd.");

	if (!isRenewable())
	    throw new RefreshFailedException("This ticket is not renewable");

	if (System.currentTimeMillis() > getRenewTill().getTime())
	    throw new RefreshFailedException("This ticket is past "
					     + "its last renewal time.");
	Throwable e = null;
	sun.security.krb5.Credentials krb5Creds = null;

	try {
	    krb5Creds = new sun.security.krb5.Credentials(asn1Encoding,
						    client.toString(),
						    server.toString(),
						    sessionKey.getEncoded(),
						    sessionKey.getKeyType(),
						    flags,
						    authTime,
						    startTime,
						    endTime,
						    renewTill,
						    clientAddresses);
	    krb5Creds = krb5Creds.renew();
	} catch (sun.security.krb5.KrbException krbException) {
	    e = krbException;
	} catch (java.io.IOException ioException) {
	    e = ioException;
	}

	if (e != null) {
	    RefreshFailedException rfException
		= new RefreshFailedException("Failed to renew Kerberos Ticket "
					     + "for client " + client 
					     + " and server " + server
					     + " - " + e.getMessage());
	    rfException.initCause(e);
	    throw rfException;
	}

	/*
	 * In case multiple threads try to refresh it at the same time.
	 */
	synchronized (this) {
	    try {
		this.destroy();
	    } catch (DestroyFailedException dfException) {
		// Squelch it since we don't care about the old ticket.
	    }
	    init(krb5Creds.getEncoded(),
		 new KerberosPrincipal(krb5Creds.getClient().getName()),
		 new KerberosPrincipal(krb5Creds.getServer().getName()),
		 krb5Creds.getSessionKey().getBytes(), 
		 krb5Creds.getSessionKey().getEType(), 
		 krb5Creds.getFlags(), 
		 krb5Creds.getAuthTime(), 
		 krb5Creds.getStartTime(), 
		 krb5Creds.getEndTime(), 
		 krb5Creds.getRenewTill(), 
		 krb5Creds.getClientAddresses());
	    destroyed = false;
	}
    }

    /**
     * Destroys the ticket and destroys any sensitive information stored in
     * it.
     */
    public void destroy() throws DestroyFailedException {
	if (!destroyed) {
	    Arrays.fill(asn1Encoding, (byte) 0);
	    client = null;
	    server = null;
	    sessionKey.destroy();
	    flags = null;
	    authTime = null;
	    startTime = null;
	    endTime = null;
	    renewTill = null;
	    clientAddresses = null;
	    destroyed = true;
	}
    }

    /** 
     * Determines if this ticket has been destroyed.
     */
    public boolean isDestroyed() {
	return destroyed;
    }

    public String toString() {
	if (destroyed)
	    throw new IllegalStateException("This ticket is no longer valid");
	StringBuffer caddrBuf = new StringBuffer();
	if (clientAddresses != null) {
	    for (int i = 0; i < clientAddresses.length; i++) {
		caddrBuf.append("clientAddresses[" + i + "] = " + 
				 clientAddresses[i].toString());
	    }
	}
	return ("Ticket (hex) = " + "\n" +
		 (new HexDumpEncoder()).encode(asn1Encoding) + "\n" +
		"Client Principal = " + client.toString() + "\n" +
		"Server Principal = " + server.toString() + "\n" +
		"Session Key = " + sessionKey.toString() + "\n" +
		"Forwardable Ticket " + flags[FORWARDABLE_TICKET_FLAG] + "\n" +
		"Forwarded Ticket " + flags[FORWARDED_TICKET_FLAG] + "\n" +
	        "Proxiable Ticket " + flags[PROXIABLE_TICKET_FLAG] + "\n" +
	        "Proxy Ticket " + flags[PROXY_TICKET_FLAG] + "\n" +
	        "Postdated Ticket " + flags[POSTDATED_TICKET_FLAG] + "\n" +
	        "Renewable Ticket " + flags[RENEWABLE_TICKET_FLAG] + "\n" +
	        "Initial Ticket " + flags[RENEWABLE_TICKET_FLAG] + "\n" +
		"Auth Time = " + authTime.toString() + "\n" +
		"Start Time = " + startTime.toString() + "\n" +
		"End Time = " + endTime.toString() + "\n" +
		"Renew Till = " +
		  (renewTill == null ? "Null " : renewTill.toString()) + "\n" +
		"Client Addresses " +
		(clientAddresses == null ? " Null " : caddrBuf.toString() +
		"\n"));
    }

}