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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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,

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 *

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package javax.security.auth.kerberos;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.ObjectStreamField;

import java.security.BasicPermission;

import java.security.Permission;

import java.security.PermissionCollection;

import java.util.*;

import java.util.concurrent.ConcurrentHashMap;

/**

 * This class is used to restrict the usage of the Kerberos

 * delegation model, ie: forwardable and proxiable tickets.

 * <p>

 * The target name of this {@code Permission} specifies a pair of

 * kerberos service principals. The first is the subordinate service principal

 * being entrusted to use the TGT. The second service principal designates

 * the target service the subordinate service principal is to

 * interact with on behalf of the initiating KerberosPrincipal. This

 * latter service principal is specified to restrict the use of a

 * proxiable ticket.

 * <p>

 * For example, to specify the "host" service use of a forwardable TGT the

 * target permission is specified as follows:

 *

 * <pre>

 *  DelegationPermission("\"host/foo.example.com@EXAMPLE.COM\" \"krbtgt/EXAMPLE.COM@EXAMPLE.COM\"");

 * </pre>

 * <p>

 * To give the "backup" service a proxiable nfs service ticket the target permission

 * might be specified:

 *

 * <pre>

 *  DelegationPermission("\"backup/bar.example.com@EXAMPLE.COM\" \"nfs/home.EXAMPLE.COM@EXAMPLE.COM\"");

 * </pre>

 *

 * @since 1.4

 */

public final class DelegationPermission extends BasicPermission

    implements java.io.Serializable {

    private static final long serialVersionUID = 883133252142523922L;

    private transient String subordinate, service;

    /**

     * Create a new {@code DelegationPermission}

     * with the specified subordinate and target principals.

     *

     * @param principals the name of the subordinate and target principals

     *

     * @throws NullPointerException if {@code principals} is {@code null}.

     */

    public DelegationPermission(String principals) {

        super(principals);

        init(principals);

    }

    /**

     * Create a new {@code DelegationPermission}

     * with the specified subordinate and target principals.

     *

     * @param principals the name of the subordinate and target principals

     *

     * @param actions should be null.

     *

     * @throws NullPointerException if {@code principals} is {@code null}.

     */

    public DelegationPermission(String principals, String actions) {

        super(principals, actions);

        init(principals);

    }

    /**

     * Initialize the DelegationPermission object.

     */

    private void init(String target) {

        StringTokenizer t = null;

        if (!target.startsWith("\"")) {

            throw new IllegalArgumentException

                ("service principal [" + target +

                 "] syntax invalid: " +

                 "improperly quoted");

        } else {

            t = new StringTokenizer(target, "\"", false);

            subordinate = t.nextToken();

            }

        }

    }

    /**

     * Checks if this Kerberos delegation permission object "implies" the

     * specified permission.

     * <P>

     * This method returns true if this {@code DelegationPermission}

     * is equal to {@code p}, and returns false otherwise.

     *

     * @param p the permission to check against.

     *

     * @return true if the specified permission is implied by this object,

     * false if not.

     */

    @Override

    public boolean implies(Permission p) {

        return equals(p);

    }

    /**

     * Checks two DelegationPermission objects for equality.

     *

     * @param obj the object to test for equality with this object.

     *

     * @return true if {@code obj} is a DelegationPermission, and

     *  has the same subordinate and service principal as this

     *  DelegationPermission object.

     */

    @Override

    public boolean equals(Object obj) {

        if (obj == this) {

            return true;

        }

        if (!(obj instanceof DelegationPermission)) {

            return false;

        }

        DelegationPermission that = (DelegationPermission) obj;

        return this.subordinate.equals(that.subordinate) &&

                this.service.equals(that.service);

    }

    /**

     * Returns the hash code value for this object.

     *

     * @return a hash code value for this object.

     */

    @Override

    public int hashCode() {

        return 17 * subordinate.hashCode() + 31 * service.hashCode();

    }

    /**

     * Returns a PermissionCollection object for storing

     * DelegationPermission objects.

     * <br>

     * DelegationPermission objects must be stored in a manner that

     * allows them to be inserted into the collection in any order, but

     * that also enables the PermissionCollection implies method to

     * be implemented in an efficient (and consistent) manner.

     *

     * @return a new PermissionCollection object suitable for storing

     * DelegationPermissions.

     */

    @Override

    public PermissionCollection newPermissionCollection() {

        return new KrbDelegationPermissionCollection();

    }

    /**

     * WriteObject is called to save the state of the DelegationPermission

     * to a stream. The actions are serialized, and the superclass

     * takes care of the name.

     */

    private synchronized void writeObject(java.io.ObjectOutputStream s)

        throws IOException

    {

        s.defaultWriteObject();

    }

    /**

     * readObject is called to restore the state of the

     * DelegationPermission from a stream.

     */

    private synchronized void readObject(java.io.ObjectInputStream s)

         throws IOException, ClassNotFoundException

    {

        // Read in the action, then initialize the rest

        s.defaultReadObject();

        init(getName());

    }

}

final class KrbDelegationPermissionCollection extends PermissionCollection

    implements java.io.Serializable {

    // Not serialized; see serialization section at end of class.

    private transient ConcurrentHashMap<Permission, Boolean> perms;

    public KrbDelegationPermissionCollection() {

        perms = new ConcurrentHashMap<>();

    }

    /**

     * Check and see if this collection of permissions implies the permissions

     * expressed in "permission".

     *

     * @param permission the Permission object to compare

     *

     * @return true if "permission" is a proper subset of a permission in

     * the collection, false if not.

     */

    @Override

    public boolean implies(Permission permission) {

        if (! (permission instanceof DelegationPermission))

            return false;

        // if map contains key, then it automatically implies it

        return perms.containsKey(permission);

    }

    /**

     * Adds a permission to the DelegationPermissions. The key for

     * the hash is the name.

     *

     * @param permission the Permission object to add.

     *

     * @exception IllegalArgumentException - if the permission is not a

     *                                       DelegationPermission

     *

     * @exception SecurityException - if this PermissionCollection object

     *                                has been marked readonly

     */

    @Override

    public void add(Permission permission) {

        if (! (permission instanceof DelegationPermission))

            throw new IllegalArgumentException("invalid permission: "+

                                               permission);

        if (isReadOnly())

            throw new SecurityException("attempt to add a Permission to a readonly PermissionCollection");

        perms.put(permission, Boolean.TRUE);

    }

    /**

     * Returns an enumeration of all the DelegationPermission objects

     * in the container.

     *

     * @return an enumeration of all the DelegationPermission objects.

     */

    @Override

    public Enumeration<Permission> elements() {

        return perms.keys();

    }

    private static final long serialVersionUID = -3383936936589966948L;

    // Need to maintain serialization interoperability with earlier releases,

    // which had the serializable field:

    //    private Vector permissions;

    /**

     * @serialField permissions java.util.Vector

     *     A list of DelegationPermission objects.

     */

    private static final ObjectStreamField[] serialPersistentFields = {

        new ObjectStreamField("permissions", Vector.class),

    };

    /**

     * @serialData "permissions" field (a Vector containing the DelegationPermissions).

     */

    /*

     * Writes the contents of the perms field out as a Vector for

     * serialization compatibility with earlier releases.

     */

    private void writeObject(ObjectOutputStream out) throws IOException {

        // Don't call out.defaultWriteObject()

        // Write out Vector

        Vector<Permission> permissions = new Vector<>(perms.keySet());

        ObjectOutputStream.PutField pfields = out.putFields();

        pfields.put("permissions", permissions);

        out.writeFields();

    }

    /*

     * Reads in a Vector of DelegationPermissions and saves them in the perms field.

     */

    @SuppressWarnings("unchecked")

    private void readObject(ObjectInputStream in)

        throws IOException, ClassNotFoundException

    {

        // Don't call defaultReadObject()

        // Read in serialized fields

        ObjectInputStream.GetField gfields = in.readFields();

        // Get the one we want

        Vector<Permission> permissions =

            (Vector<Permission>)gfields.get("permissions", null);

        perms = new ConcurrentHashMap<>(permissions.size());

        for (Permission perm : permissions) {

            perms.put(perm, Boolean.TRUE);

        }

    }

}