/*
 * Copyright 2000-2006 Sun Microsystems, Inc.  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.  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.
 */

package sun.security.jgss.krb5;

import org.ietf.jgss.*;
import sun.security.jgss.GSSUtil;
import sun.security.jgss.spi.*;
import sun.security.krb5.*;
import javax.security.auth.kerberos.*;
import java.io.IOException;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.security.AccessController;
import java.security.AccessControlContext;
import javax.security.auth.DestroyFailedException;

/**
 * Implements the krb5 acceptor credential element.
 *
 * @author Mayank Upadhyay
 * @since 1.4
 */
public class Krb5AcceptCredential
    extends KerberosKey
    implements Krb5CredElement {

    private static final long serialVersionUID = 7714332137352567952L;

    private Krb5NameElement name;

    /**
     * We cache an EncryptionKey representation of this key because many
     * Krb5 operation require a key in that form. At some point we might do
     * away with EncryptionKey altogether and use the base class
     * KerberosKey everywhere.
     */
    private EncryptionKey[] krb5EncryptionKeys;

    private Krb5AcceptCredential(Krb5NameElement name, KerberosKey[] keys) {
        /*
         * Initialize this instance with the data from the acquired
         * KerberosKey. This class needs to be a KerberosKey too
         * hence we can't just store a reference.
         */
        super(keys[0].getPrincipal(),
              keys[0].getEncoded(),
              keys[0].getKeyType(),
              keys[0].getVersionNumber());

        this.name = name;
        // Cache this for later use by the sun.security.krb5 package.
        krb5EncryptionKeys = new EncryptionKey[keys.length];
        for (int i = 0; i < keys.length; i++) {
            krb5EncryptionKeys[i] = new EncryptionKey(keys[i].getEncoded(),
                                    keys[i].getKeyType(),
                                    new Integer(keys[i].getVersionNumber()));
        }
    }

    static Krb5AcceptCredential getInstance(final int caller, Krb5NameElement name)
        throws GSSException {

        final String serverPrinc = (name == null? null:
            name.getKrb5PrincipalName().getName());
        final AccessControlContext acc = AccessController.getContext();

        KerberosKey[] keys;
        try {
            keys = AccessController.doPrivileged(
                        new PrivilegedExceptionAction<KerberosKey[]>() {
                public KerberosKey[] run() throws Exception {
                    return Krb5Util.getKeys(
                        caller == GSSUtil.CALLER_UNKNOWN ? GSSUtil.CALLER_ACCEPT: caller,
                        serverPrinc, acc);
                }});
        } catch (PrivilegedActionException e) {
            GSSException ge =
                new GSSException(GSSException.NO_CRED, -1,
                    "Attempt to obtain new ACCEPT credentials failed!");
            ge.initCause(e.getException());
            throw ge;
        }

        if (keys == null || keys.length == 0)
            throw new GSSException(GSSException.NO_CRED, -1,
                                   "Failed to find any Kerberos Key");

        if (name == null) {
            String fullName = keys[0].getPrincipal().getName();
            name = Krb5NameElement.getInstance(fullName,
                                       Krb5MechFactory.NT_GSS_KRB5_PRINCIPAL);
        }

        return new Krb5AcceptCredential(name, keys);
    }

    /**
     * Returns the principal name for this credential. The name
     * is in mechanism specific format.
     *
     * @return GSSNameSpi representing principal name of this credential
     * @exception GSSException may be thrown
     */
    public final GSSNameSpi getName() throws GSSException {
        return name;
    }

    /**
     * Returns the init lifetime remaining.
     *
     * @return the init lifetime remaining in seconds
     * @exception GSSException may be thrown
     */
    public int getInitLifetime() throws GSSException {
        return 0;
    }

    /**
     * Returns the accept lifetime remaining.
     *
     * @return the accept lifetime remaining in seconds
     * @exception GSSException may be thrown
     */
    public int getAcceptLifetime() throws GSSException {
        return GSSCredential.INDEFINITE_LIFETIME;
    }

    public boolean isInitiatorCredential() throws GSSException {
        return false;
    }

    public boolean isAcceptorCredential() throws GSSException {
        return true;
    }

    /**
     * Returns the oid representing the underlying credential
     * mechanism oid.
     *
     * @return the Oid for this credential mechanism
     * @exception GSSException may be thrown
     */
    public final Oid getMechanism() {
        return Krb5MechFactory.GSS_KRB5_MECH_OID;
    }

    public final java.security.Provider getProvider() {
        return Krb5MechFactory.PROVIDER;
    }

    EncryptionKey[] getKrb5EncryptionKeys() {
        return krb5EncryptionKeys;
    }

    /**
     * Called to invalidate this credential element.
     */
    public void dispose() throws GSSException {
        try {
            destroy();
        } catch (DestroyFailedException e) {
            GSSException gssException =
                new GSSException(GSSException.FAILURE, -1,
                 "Could not destroy credentials - " + e.getMessage());
            gssException.initCause(e);
        }
    }

    /**
     * Destroys the locally cached EncryptionKey value and then calls
     * destroy in the base class.
     */
    public void destroy() throws DestroyFailedException {
        if (krb5EncryptionKeys != null) {
            for (int i = 0; i < krb5EncryptionKeys.length; i++) {
                krb5EncryptionKeys[i].destroy();
            }
            krb5EncryptionKeys = null;
        }

        super.destroy();
    }
}