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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.
 The target name of this 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. 

For example, to specify the "host" service use of a forwardable TGT the
target permission is specified as follows:
 DelegationPermission("\"host/foo.example.com@EXAMPLE.COM\" \"krbtgt/EXAMPLE.COM@EXAMPLE.COM\"");


To give the "backup" service a proxiable nfs service ticket the target permission
might be specified:
 DelegationPermission("\"backup/bar.example.com@EXAMPLE.COM\" \"nfs/home.EXAMPLE.COM@EXAMPLE.COM\"");

Since:
1.4/**
 * 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 DelegationPermission with the specified subordinate and target principals. 
Params:
principals – the name of the subordinate and target principals
Throws:
NullPointerException – if principals is null.
IllegalArgumentException – if principals is empty./**
     * 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}.
     * @throws IllegalArgumentException if {@code principals} is empty.
     */
    public DelegationPermission(String principals) {
        super(principals);
        init(principals);
    }

    
Create a new DelegationPermission with the specified subordinate and target principals. 
Params:
principals – the name of the subordinate and target principals
actions – should be null.
Throws:
NullPointerException – if principals is null.
IllegalArgumentException – if principals is empty./**
     * 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}.
     * @throws IllegalArgumentException if {@code principals} is empty.
     */
    public DelegationPermission(String principals, String actions) {
        super(principals, actions);
        init(principals);
    }


    
Initialize the DelegationPermission object.
/**
     * 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();
            if (t.countTokens() == 2) {
                t.nextToken();  // bypass whitespace
                service = t.nextToken();
            } else if (t.countTokens() > 0) {
                throw new IllegalArgumentException
                    ("service principal [" + t.nextToken() +
                     "] syntax invalid: " +
                     "improperly quoted");
            }
        }
    }

    
Checks if this Kerberos delegation permission object "implies" the
specified permission.
 This method returns true if this DelegationPermission is equal to p, and returns false otherwise. 
Params:
p – the permission to check against.
Returns:
true if the specified permission is implied by this object,
false if not./**
     * 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.
Params:
obj – the object to test for equality with this object.
Returns:
true if obj is a DelegationPermission, and has the same subordinate and service principal as this DelegationPermission object./**
     * 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.
Returns:
a hash code value for this object./**
     * 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.


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.
Returns:
a new PermissionCollection object suitable for storing
DelegationPermissions./**
     * 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.
/**
     * 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.
/**
     * 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".
Params:
permission – the Permission object to compare
Returns:
true if "permission" is a proper subset of a permission in
the collection, false if not./**
     * 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.
Params:
permission – the Permission object to add.
Throws:
IllegalArgumentException – - if the permission is not a
                                      DelegationPermission
SecurityException – - if this PermissionCollection object
                               has been marked readonly/**
     * 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.
Returns:
an enumeration of all the DelegationPermission objects./**
     * 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./**
     * @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)./**
     * @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);
        }
    }
}