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	/*
	* Copyright (c) 2000, 2013, 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.util.*;
	import java.security.Permission;
	import java.security.PermissionCollection;
	import java.io.ObjectStreamField;
	import java.io.ObjectOutputStream;
	import java.io.ObjectInputStream;
	import java.io.IOException;

	/**
	* This class is used to protect Kerberos services and the
	* credentials necessary to access those services. There is a one to
	* one mapping of a service principal and the credentials necessary
	* to access the service. Therefore granting access to a service
	* principal implicitly grants access to the credential necessary to
	* establish a security context with the service principal. This
	* applies regardless of whether the credentials are in a cache
	* or acquired via an exchange with the KDC. The credential can
	* be either a ticket granting ticket, a service ticket or a secret
	* key from a key table.
	* <p>
	* A ServicePermission contains a service principal name and
	* a list of actions which specify the context the credential can be
	* used within.
	* <p>
	* The service principal name is the canonical name of the
	* {@code KerberosPrincipal} supplying the service, that is
	* the KerberosPrincipal represents a Kerberos service
	* principal. This name is treated in a case sensitive manner.
	* An asterisk may appear by itself, to signify any service principal.
	* <p>
	* Granting this permission implies that the caller can use a cached
	* credential (TGT, service ticket or secret key) within the context
	* designated by the action. In the case of the TGT, granting this
	* permission also implies that the TGT can be obtained by an
	* Authentication Service exchange.
	* <p>
	* The possible actions are:
	*
	* <pre>
	* initiate - allow the caller to use the credential to
	* initiate a security context with a service
	* principal.
	*
	* accept - allow the caller to use the credential to
	* accept security context as a particular
	* principal.
	* </pre>
	*
	* For example, to specify the permission to access to the TGT to
	* initiate a security context the permission is constructed as follows:
	*
	* <pre>
	* ServicePermission("krbtgt/EXAMPLE.COM@EXAMPLE.COM", "initiate");
	* </pre>
	* <p>
	* To obtain a service ticket to initiate a context with the "host"
	* service the permission is constructed as follows:
	* <pre>
	* ServicePermission("host/foo.example.com@EXAMPLE.COM", "initiate");
	* </pre>
	* <p>
	* For a Kerberized server the action is "accept". For example, the permission
	* necessary to access and use the secret key of the Kerberized "host"
	* service (telnet and the likes) would be constructed as follows:
	*
	* <pre>
	* ServicePermission("host/foo.example.com@EXAMPLE.COM", "accept");
	* </pre>
	*
	* @since 1.4
	*/

	public final class ServicePermission extends Permission
	implements java.io.Serializable {

	private static final long serialVersionUID = -1227585031618624935L;

	/**
	* Initiate a security context to the specified service
	*/
	private final static int INITIATE = 0x1;

	/**
	* Accept a security context
	*/
	private final static int ACCEPT = 0x2;

	/**
	* All actions
	*/
	private final static int ALL = INITIATE\|ACCEPT;

	/**
	* No actions.
	*/
	private final static int NONE = 0x0;

	// the actions mask
	private transient int mask;

	/**
	* the actions string.
	*
	* @serial
	*/

	private String actions; // Left null as long as possible, then
	// created and re-used in the getAction function.

	/**
	* Create a new {@code ServicePermission}
	* with the specified {@code servicePrincipal}
	* and {@code action}.
	*
	* @param servicePrincipal the name of the service principal.
	* An asterisk may appear by itself, to signify any service principal.
	* <p>
	* @param action the action string
	*/
	public ServicePermission(String servicePrincipal, String action) {
	// Note: servicePrincipal can be "@REALM" which means any principal in
	// this realm implies it. action can be "-" which means any
	// action implies it.
	super(servicePrincipal);
	init(servicePrincipal, getMask(action));
	}


	/**
	* Initialize the ServicePermission object.
	*/
	private void init(String servicePrincipal, int mask) {

	if (servicePrincipal == null)
	throw new NullPointerException("service principal can't be null");

	if ((mask & ALL) != mask)
	throw new IllegalArgumentException("invalid actions mask");

	this.mask = mask;
	}


	/**
	* Checks if this Kerberos service permission object "implies" the
	* specified permission.
	* <P>
	* If none of the above are true, {@code implies} returns false.
	* @param p the permission to check against.
	*
	* @return true if the specified permission is implied by this object,
	* false if not.
	*/
	public boolean implies(Permission p) {
	if (!(p instanceof ServicePermission))
	return false;

	ServicePermission that = (ServicePermission) p;

	return ((this.mask & that.mask) == that.mask) &&
	impliesIgnoreMask(that);
	}


	boolean impliesIgnoreMask(ServicePermission p) {
	return ((this.getName().equals("*")) \|\|
	this.getName().equals(p.getName()) \|\|
	(p.getName().startsWith("@") &&
	this.getName().endsWith(p.getName())));
	}

	/**
	* Checks two ServicePermission objects for equality.
	* <P>
	* @param obj the object to test for equality with this object.
	*
	* @return true if <i>obj</i> is a ServicePermission, and has the
	* same service principal, and actions as this
	* ServicePermission object.
	*/
	public boolean equals(Object obj) {
	if (obj == this)
	return true;

	if (! (obj instanceof ServicePermission))
	return false;

	ServicePermission that = (ServicePermission) obj;
	return ((this.mask & that.mask) == that.mask) &&
	this.getName().equals(that.getName());


	}

	/**
	* Returns the hash code value for this object.
	*
	* @return a hash code value for this object.
	*/

	public int hashCode() {
	return (getName().hashCode() ^ mask);
	}


	/**
	* Returns the "canonical string representation" of the actions in the
	* specified mask.
	* Always returns present actions in the following order:
	* initiate, accept.
	*
	* @param mask a specific integer action mask to translate into a string
	* @return the canonical string representation of the actions
	*/
	private static String getActions(int mask)
	{
	StringBuilder sb = new StringBuilder();
	boolean comma = false;

	if ((mask & INITIATE) == INITIATE) {
	if (comma) sb.append(',');
	else comma = true;
	sb.append("initiate");
	}

	if ((mask & ACCEPT) == ACCEPT) {
	if (comma) sb.append(',');
	else comma = true;
	sb.append("accept");
	}

	return sb.toString();
	}

	/**
	* Returns the canonical string representation of the actions.
	* Always returns present actions in the following order:
	* initiate, accept.
	*/
	public String getActions() {
	if (actions == null)
	actions = getActions(this.mask);

	return actions;
	}


	/**
	* Returns a PermissionCollection object for storing
	* ServicePermission objects.
	* <br>
	* ServicePermission 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
	* ServicePermissions.
	*/
	public PermissionCollection newPermissionCollection() {
	return new KrbServicePermissionCollection();
	}

	/**
	* Return the current action mask.
	*
	* @return the actions mask.
	*/
	int getMask() {
	return mask;
	}

	/**
	* Convert an action string to an integer actions mask.
	*
	* Note: if action is "-", action will be NONE, which means any
	* action implies it.
	*
	* @param action the action string.
	* @return the action mask
	*/
	private static int getMask(String action) {

	if (action == null) {
	throw new NullPointerException("action can't be null");
	}

	if (action.equals("")) {
	throw new IllegalArgumentException("action can't be empty");
	}

	int mask = NONE;

	char[] a = action.toCharArray();

	if (a.length == 1 && a[0] == '-') {
	return mask;
	}

	int i = a.length - 1;

	while (i != -1) {
	char c;

	// skip whitespace
	while ((i!=-1) && ((c = a[i]) == ' ' \|\|
	c == '\r' \|\|
	c == '\n' \|\|
	c == '\f' \|\|
	c == '\t'))
	i--;

	// check for the known strings
	int matchlen;

	if (i >= 7 && (a[i-7] == 'i' \|\| a[i-7] == 'I') &&
	(a[i-6] == 'n' \|\| a[i-6] == 'N') &&
	(a[i-5] == 'i' \|\| a[i-5] == 'I') &&
	(a[i-4] == 't' \|\| a[i-4] == 'T') &&
	(a[i-3] == 'i' \|\| a[i-3] == 'I') &&
	(a[i-2] == 'a' \|\| a[i-2] == 'A') &&
	(a[i-1] == 't' \|\| a[i-1] == 'T') &&
	(a[i] == 'e' \|\| a[i] == 'E'))
	{
	matchlen = 8;
	mask \|= INITIATE;

	} else if (i >= 5 && (a[i-5] == 'a' \|\| a[i-5] == 'A') &&
	(a[i-4] == 'c' \|\| a[i-4] == 'C') &&
	(a[i-3] == 'c' \|\| a[i-3] == 'C') &&
	(a[i-2] == 'e' \|\| a[i-2] == 'E') &&
	(a[i-1] == 'p' \|\| a[i-1] == 'P') &&
	(a[i] == 't' \|\| a[i] == 'T'))
	{
	matchlen = 6;
	mask \|= ACCEPT;

	} else {
	// parse error
	throw new IllegalArgumentException(
	"invalid permission: " + action);
	}

	// make sure we didn't just match the tail of a word
	// like "ackbarfaccept". Also, skip to the comma.
	boolean seencomma = false;
	while (i >= matchlen && !seencomma) {
	switch(a[i-matchlen]) {
	case ',':
	seencomma = true;
	break;
	case ' ': case '\r': case '\n':
	case '\f': case '\t':
	break;
	default:
	throw new IllegalArgumentException(
	"invalid permission: " + action);
	}
	i--;
	}

	// point i at the location of the comma minus one (or -1).
	i -= matchlen;
	}

	return mask;
	}


	/**
	* WriteObject is called to save the state of the ServicePermission
	* to a stream. The actions are serialized, and the superclass
	* takes care of the name.
	*/
	private void writeObject(java.io.ObjectOutputStream s)
	throws IOException
	{
	// Write out the actions. The superclass takes care of the name
	// call getActions to make sure actions field is initialized
	if (actions == null)
	getActions();
	s.defaultWriteObject();
	}

	/**
	* readObject is called to restore the state of the
	* ServicePermission from a stream.
	*/
	private void readObject(java.io.ObjectInputStream s)
	throws IOException, ClassNotFoundException
	{
	// Read in the action, then initialize the rest
	s.defaultReadObject();
	init(getName(),getMask(actions));
	}


	/*
	public static void main(String args[]) throws Exception {
	ServicePermission this_ =
	new ServicePermission(args[0], "accept");
	ServicePermission that_ =
	new ServicePermission(args[1], "accept,initiate");
	System.out.println("-----\n");
	System.out.println("this.implies(that) = " + this_.implies(that_));
	System.out.println("-----\n");
	System.out.println("this = "+this_);
	System.out.println("-----\n");
	System.out.println("that = "+that_);
	System.out.println("-----\n");

	KrbServicePermissionCollection nps =
	new KrbServicePermissionCollection();
	nps.add(this_);
	nps.add(new ServicePermission("nfs/example.com@EXAMPLE.COM",
	"accept"));
	nps.add(new ServicePermission("host/example.com@EXAMPLE.COM",
	"initiate"));
	System.out.println("nps.implies(that) = " + nps.implies(that_));
	System.out.println("-----\n");

	Enumeration e = nps.elements();

	while (e.hasMoreElements()) {
	ServicePermission x =
	(ServicePermission) e.nextElement();
	System.out.println("nps.e = " + x);
	}

	}
	*/

	}


	final class KrbServicePermissionCollection extends PermissionCollection
	implements java.io.Serializable {

	// Not serialized; see serialization section at end of class
	private transient List<Permission> perms;

	public KrbServicePermissionCollection() {
	perms = new ArrayList<Permission>();
	}

	/**
	* 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.
	*/
	public boolean implies(Permission permission) {
	if (! (permission instanceof ServicePermission))
	return false;

	ServicePermission np = (ServicePermission) permission;
	int desired = np.getMask();

	if (desired == 0) {
	for (Permission p: perms) {
	ServicePermission sp = (ServicePermission)p;
	if (sp.impliesIgnoreMask(np)) {
	return true;
	}
	}
	return false;
	}

	int effective = 0;
	int needed = desired;

	synchronized (this) {
	int len = perms.size();

	// need to deal with the case where the needed permission has
	// more than one action and the collection has individual permissions
	// that sum up to the needed.

	for (int i = 0; i < len; i++) {
	ServicePermission x = (ServicePermission) perms.get(i);

	//System.out.println(" trying "+x);
	if (((needed & x.getMask()) != 0) && x.impliesIgnoreMask(np)) {
	effective \|= x.getMask();
	if ((effective & desired) == desired)
	return true;
	needed = (desired ^ effective);
	}
	}
	}
	return false;
	}

	/**
	* Adds a permission to the ServicePermissions. The key for
	* the hash is the name.
	*
	* @param permission the Permission object to add.
	*
	* @exception IllegalArgumentException - if the permission is not a
	* ServicePermission
	*
	* @exception SecurityException - if this PermissionCollection object
	* has been marked readonly
	*/
	public void add(Permission permission) {
	if (! (permission instanceof ServicePermission))
	throw new IllegalArgumentException("invalid permission: "+
	permission);
	if (isReadOnly())
	throw new SecurityException("attempt to add a Permission to a readonly PermissionCollection");

	synchronized (this) {
	perms.add(0, permission);
	}
	}

	/**
	* Returns an enumeration of all the ServicePermission objects
	* in the container.
	*
	* @return an enumeration of all the ServicePermission objects.
	*/

	public Enumeration<Permission> elements() {
	// Convert Iterator into Enumeration
	synchronized (this) {
	return Collections.enumeration(perms);
	}
	}

	private static final long serialVersionUID = -4118834211490102011L;

	// Need to maintain serialization interoperability with earlier releases,
	// which had the serializable field:
	// private Vector permissions;

	/**
	* @serialField permissions java.util.Vector
	* A list of ServicePermission objects.
	*/
	private static final ObjectStreamField[] serialPersistentFields = {
	new ObjectStreamField("permissions", Vector.class),
	};

	/**
	* @serialData "permissions" field (a Vector containing the ServicePermissions).
	*/
	/*
	* 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.size());

	synchronized (this) {
	permissions.addAll(perms);
	}

	ObjectOutputStream.PutField pfields = out.putFields();
	pfields.put("permissions", permissions);
	out.writeFields();
	}

	/*
	* Reads in a Vector of ServicePermissions 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 ArrayList<Permission>(permissions.size());
	perms.addAll(permissions);
	}
	}

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