/*

 * Copyright (c) 2011, 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.

 */

package javax.security.auth.kerberos;

import java.io.File;

import java.util.Objects;

import sun.security.krb5.EncryptionKey;

import sun.security.krb5.KerberosSecrets;

import sun.security.krb5.PrincipalName;

import sun.security.krb5.RealmException;

/**

 * This class encapsulates a keytab file.

 * <p>

 * A Kerberos JAAS login module that obtains long term secret keys from a

 * keytab file should use this class. The login module will store

 * an instance of this class in the private credential set of a

 * {@link javax.security.auth.Subject Subject} during the commit phase of the

 * authentication process.

 * <p>

 * It might be necessary for the application to be granted a

 * {@link javax.security.auth.PrivateCredentialPermission

 * PrivateCredentialPermission} if it needs to access the KeyTab

 * instance from a Subject. This permission is not needed when the

 * application depends on the default JGSS Kerberos mechanism to access the

 * KeyTab. In that case, however, the application will need an appropriate

 * {@link javax.security.auth.kerberos.ServicePermission ServicePermission}.

 * <p>

 * The keytab file format is described at

 * <a href="http://www.ioplex.com/utilities/keytab.txt">

 * http://www.ioplex.com/utilities/keytab.txt</a>.

 * @since 1.7

 */

public final class KeyTab {

    /*

     * Impl notes:

     *

     * This class is only a name, a permanent link to the keytab source

     * (can be missing). Itself has no content. In order to read content,

     * take a snapshot and read from it.

     *

     * The snapshot is of type sun.security.krb5.internal.ktab.KeyTab, which

     * contains the content of the keytab file when the snapshot is taken.

     * Itself has no refresh function and mostly an immutable class (except

     * for the create/add/save methods only used by the ktab command).

     */

    // Source, null if using the default one. Note that the default name

    // is maintained in snapshot, this field is never "resolved".

    private final File file;

    // Set up JavaxSecurityAuthKerberosAccess in KerberosSecrets

    static {

        KerberosSecrets.setJavaxSecurityAuthKerberosAccess(

                new JavaxSecurityAuthKerberosAccessImpl());

    }

        this.file = file;

    }

    /**

     * <p>

     * The result of this method is never null. This method only associates

     * the returned {@code KeyTab} object with the file and does not read it.

     * @param file the keytab {@code File} object, must not be null

     * @return the keytab instance

     * @throws NullPointerException if the {@code file} argument is null

     */

    public static KeyTab getInstance(File file) {

        if (file == null) {

            throw new NullPointerException("file must be non null");

        }

    }

    /**

     * <p>

     * The result of this method is never null. This method only associates

     * the returned {@code KeyTab} object with the default keytab file and

     * does not read it.

     * @return the default keytab instance.

     */

    public static KeyTab getInstance() {

    }

    //Takes a snapshot of the keytab content

        return sun.security.krb5.internal.ktab.KeyTab.getInstance(file);

    }

    /**

     * Returns fresh keys for the given Kerberos principal.

     * <p>

     * Implementation of this method should make sure the returned keys match

     * the latest content of the keytab file. The result is a newly created

     * copy that can be modified by the caller without modifying the keytab

     * object. The caller should {@link KerberosKey#destroy() destroy} the

     * result keys after they are used.

     * <p>

     * Please note that the keytab file can be created after the

     * {@code KeyTab} object is instantiated and its content may change over

     * time. Therefore, an application should call this method only when it

     * needs to use the keys. Any previous result from an earlier invocation

     * could potentially be expired.

     * <p>

     * If there is any error (say, I/O error or format error)

     * during the reading process of the KeyTab file, a saved result should be

     * returned. If there is no saved result (say, this is the first time this

     * method is called, or, all previous read attempts failed), an empty array

     * should be returned. This can make sure the result is not drastically

     * changed during the (probably slow) update of the keytab file.

     * <p>

     * Each time this method is called and the reading of the file succeeds

     * with no exception (say, I/O error or file format error),

     * the result should be saved for {@code principal}. The implementation can

     * also save keys for other principals having keys in the same keytab object

     * if convenient.

     * <p>

     * Any unsupported key read from the keytab is ignored and not included

     * in the result.

     *

     * @param principal the Kerberos principal, must not be null.

     * @return the keys (never null, may be empty)

     * @throws NullPointerException if the {@code principal}

     * argument is null

     * @throws SecurityException if a security manager exists and the read

     * access to the keytab file is not permitted

     */

    public KerberosKey[] getKeys(KerberosPrincipal principal) {

        try {

            KerberosKey[] kks = new KerberosKey[keys.length];

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

                Integer tmp = keys[i].getKeyVersionNumber();

                kks[i] = new KerberosKey(

                        principal,

                        keys[i].getBytes(),

                        keys[i].getEType(),

                        tmp == null ? 0 : tmp.intValue());

                keys[i].destroy();

            }

            return kks;

        } catch (RealmException re) {

            return new KerberosKey[0];

        }

    }

    EncryptionKey[] getEncryptionKeys(PrincipalName principal) {

        return takeSnapshot().readServiceKeys(principal);

    }

    /**

     * Checks if the keytab file exists. Implementation of this method

     * should make sure that the result matches the latest status of the

     * keytab file.

     * <p>

     * The caller can use the result to determine if it should fallback to

     * another mechanism to read the keys.

     * @return true if the keytab file exists; false otherwise.

     * @throws SecurityException if a security manager exists and the read

     * access to the keytab file is not permitted

     */

    public boolean exists() {

        return !takeSnapshot().isMissing();

    }

    public String toString() {

    }

    /**

     * Returns a hashcode for this KeyTab.

     *

     * @return a hashCode() for the <code>KeyTab</code>

     */

    public int hashCode() {

    }

    /**

     * Compares the specified Object with this KeyTab for equality.

     * Returns true if the given object is also a

     * <code>KeyTab</code> and the two

     * <code>KeyTab</code> instances are equivalent.

     *

     * @param other the Object to compare to

     * @return true if the specified object is equal to this KeyTab

     */

    public boolean equals(Object other) {

        if (other == this)

            return true;

        if (! (other instanceof KeyTab)) {

            return false;

        }

        KeyTab otherKtab = (KeyTab) other;

    }

}