WirePermission


1   /*
2    * $Header: /cvshome/build/org.osgi.service.wireadmin/src/org/osgi/service/wireadmin/WirePermission.java,v 1.13 2006/07/12 21:22:14 hargrave Exp $
3    *
4    * Copyright (c) OSGi Alliance (2002, 2006). All Rights Reserved.
5    *
6    * Licensed under the Apache License, Version 2.0 (the "License");
7    * you may not use this file except in compliance with the License.
8    * You may obtain a copy of the License at
9    *
10   *      http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.osgi.service.wireadmin;
19  
20  import java.io.IOException  ;
21  import java.security.*;
22  import java.util.Enumeration  ;
23  import java.util.Hashtable  ;
24  
25  /**
26   * Permission for the scope of a <code>Wire</code> object. When a
27   * <code>Envelope</code> object is used for communication with the <code>poll</code>
28   * or <code>update</code> method, and the scope is set, then the <code>Wire</code>
29   * object must verify that the Consumer service has
30   * <code>WirePermission[name,CONSUME]</code> and the Producer service has
31   * <code>WirePermission[name,PRODUCE]</code> for all names in the scope.
32   * <p>
33   * The names are compared with the normal rules for permission names. This means
34   * that they may end with a "*" to indicate wildcards. E.g. Door.* indicates all
35   * scope names starting with the string "Door". The last period is required due
36   * to the implementations of the <code>BasicPermission</code> class.
37   * 
38   * @version $Revision: 1.13 $
39   */
40  final public class WirePermission extends BasicPermission {
41      static final long serialVersionUID = -5583709391516569321L;
42      /**
43       * The action string for the <code>PRODUCE</code> action: value is "produce".
44       */
45      public static final String    PRODUCE         = "produce";
46      /**
47       * The action string for the <code>CONSUME</code> action: value is "consume".
48       */
49      public static final String    CONSUME         = "consume";
50      private final static int    ACTION_PRODUCE  = 0x00000001;
51      private final static int    ACTION_CONSUME  = 0x00000002;
52      private final static int    ACTION_ALL      = ACTION_PRODUCE
53                                                          | ACTION_CONSUME;
54      private final static int    ACTION_NONE     = 0;
55      /**
56       * The actions mask.
57       */
58      private transient int       action_mask     = ACTION_NONE;
59      /**
60       * The actions in canonical form.
61       * 
62       * @serial
63       */
64      private String                actions         = null;
65  
66      /**
67       * Create a new WirePermission with the given name (may be wildcard) and
68       * actions.
69       * @param name Wire name.
70       * @param actions <code>produce</code>, <code>consume</code>
71       *        (canonical order).
72       */
73      public WirePermission(String   name, String   actions) {
74          this(name, getMask(actions));
75      }
76  
77      /**
78       * Package private constructor used by WirePermissionCollection.
79       * 
80       * @param name class name
81       * @param mask action mask
82       */
83      WirePermission(String   name, int mask) {
84          super(name);
85          init(mask);
86      }
87  
88      /**
89       * Called by constructors and when deserialized.
90       * 
91       * @param mask action mask
92       */
93      private void init(int mask) {
94          if ((mask == ACTION_NONE) || ((mask & ACTION_ALL) != mask)) {
95              throw new IllegalArgumentException  ("invalid action string");
96          }
97          action_mask = mask;
98      }
99  
100     /**
101      * Parse action string into action mask.
102      * 
103      * @param actions Action string.
104      * @return action mask.
105      */
106     private static int getMask(String   actions) {
107         boolean seencomma = false;
108         int mask = ACTION_NONE;
109         if (actions == null) {
110             return mask;
111         }
112         char[] a = actions.toCharArray();
113         int i = a.length - 1;
114         if (i < 0)
115             return mask;
116         while (i != -1) {
117             char c;
118             // skip whitespace
119             while ((i != -1)
120                     && ((c = a[i]) == ' ' || c == '\r' || c == '\n'
121                             || c == '\f' || c == '\t'))
122                 i--;
123             // check for the known strings
124             int matchlen;
125             if (i >= 6 && (a[i - 6] == 'p' || a[i - 6] == 'P')
126                     && (a[i - 5] == 'r' || a[i - 5] == 'R')
127                     && (a[i - 4] == 'o' || a[i - 4] == 'O')
128                     && (a[i - 3] == 'd' || a[i - 3] == 'D')
129                     && (a[i - 2] == 'u' || a[i - 2] == 'U')
130                     && (a[i - 1] == 'c' || a[i - 1] == 'C')
131                     && (a[i] == 'e' || a[i] == 'E')) {
132                 matchlen = 7;
133                 mask |= ACTION_PRODUCE;
134             }
135             else
136                 if (i >= 6 && (a[i - 6] == 'c' || a[i - 6] == 'C')
137                         && (a[i - 5] == 'o' || a[i - 5] == 'O')
138                         && (a[i - 4] == 'n' || a[i - 4] == 'N')
139                         && (a[i - 3] == 's' || a[i - 3] == 'S')
140                         && (a[i - 2] == 'u' || a[i - 2] == 'U')
141                         && (a[i - 1] == 'm' || a[i - 1] == 'M')
142                         && (a[i] == 'e' || a[i] == 'E')) {
143                     matchlen = 7;
144                     mask |= ACTION_CONSUME;
145                 }
146                 else {
147                     // parse error
148                     throw new IllegalArgumentException  ("invalid permission: "
149                             + actions);
150                 }
151             // make sure we didn't just match the tail of a word
152             // like "ackbarfregister". Also, skip to the comma.
153             seencomma = false;
154             while (i >= matchlen && !seencomma) {
155                 switch (a[i - matchlen]) {
156                     case ',' :
157                         seencomma = true;
158                     /* FALLTHROUGH */
159                     case ' ' :
160                     case '\r' :
161                     case '\n' :
162                     case '\f' :
163                     case '\t' :
164                         break;
165                     default :
166                         throw new IllegalArgumentException  (
167                                 "invalid permission: " + actions);
168                 }
169                 i--;
170             }
171             // point i at the location of the comma minus one (or -1).
172             i -= matchlen;
173         }
174         if (seencomma) {
175             throw new IllegalArgumentException  ("invalid permission: " + actions);
176         }
177         return mask;
178     }
179 
180     /**
181      * Checks if this <code>WirePermission</code> object <code>implies</code> the
182      * specified permission.
183      * <P>
184      * More specifically, this method returns <code>true</code> if:
185      * <p>
186      * <ul>
187      * <li><i>p </i> is an instanceof the <code>WirePermission</code> class,
188      * <li><i>p </i>'s actions are a proper subset of this object's actions,
189      * and
190      * <li><i>p </i>'s name is implied by this object's name. For example,
191      * <code>java.*</code> implies <code>java.home</code>.
192      * </ul>
193      * 
194      * @param p The permission to check against.
195      * 
196      * @return <code>true</code> if the specified permission is implied by this
197      *         object; <code>false</code> otherwise.
198      */
199     public boolean implies(Permission p) {
200         if (p instanceof WirePermission) {
201             WirePermission target = (WirePermission) p;
202             return ((action_mask & target.action_mask) == target.action_mask)
203                     && super.implies(p);
204         }
205         return false;
206     }
207 
208     /**
209      * Returns the canonical string representation of the actions. Always
210      * returns present actions in the following order: <code>produce</code>,
211      * <code>consume</code>.
212      * 
213      * @return The canonical string representation of the actions.
214      */
215     public String   getActions() {
216         if (actions == null) {
217             StringBuffer   sb = new StringBuffer  ();
218             boolean comma = false;
219             if ((action_mask & ACTION_PRODUCE) == ACTION_PRODUCE) {
220                 sb.append(PRODUCE);
221                 comma = true;
222             }
223             if ((action_mask & ACTION_CONSUME) == ACTION_CONSUME) {
224                 if (comma)
225                     sb.append(',');
226                 sb.append(CONSUME);
227             }
228             actions = sb.toString();
229         }
230         return actions;
231     }
232 
233     /**
234      * Returns a new <code>PermissionCollection</code> object for storing
235      * <code>WirePermission</code> objects.
236      * 
237      * @return A new <code>PermissionCollection</code> object suitable for storing
238      *         <code>WirePermission</code> objects.
239      */
240     public PermissionCollection newPermissionCollection() {
241         return new WirePermissionCollection();
242     }
243 
244     /**
245      * Determines the equalty of two <code>WirePermission</code> objects.
246      * 
247      * Checks that specified object has the same name and actions as this
248      * <code>WirePermission</code> object.
249      * 
250      * @param obj The object to test for equality.
251      * @return true if <code>obj</code> is a <code>WirePermission</code>, and has
252      *         the same name and actions as this <code>WirePermission</code>
253      *         object; <code>false</code> otherwise.
254      */
255     public boolean equals(Object   obj) {
256         if (obj == this) {
257             return true;
258         }
259         if (!(obj instanceof WirePermission)) {
260             return false;
261         }
262         WirePermission p = (WirePermission) obj;
263         return (action_mask == p.action_mask) && getName().equals(p.getName());
264     }
265 
266     /**
267      * Returns the hash code value for this object.
268      * 
269      * @return Hash code value for this object.
270      */
271     public int hashCode() {
272         return getName().hashCode() ^ getActions().hashCode();
273     }
274 
275     /**
276      * Returns the current action mask. Used by the WirePermissionCollection
277      * object.
278      * 
279      * @return The actions mask.
280      */
281     int getMask() {
282         return action_mask;
283     }
284 
285     /**
286      * Returns a string describing this <code>WirePermission</code>. The
287      * convention is to specify the class name, the permission name, and the
288      * actions in the following format:
289      * '(org.osgi.service.wireadmin.WirePermission &quot;name&quot;
290      * &quot;actions&quot;)'.
291      * 
292      * @return information about this <code>Permission</code> object.
293      */
294     public String   toString() {
295         StringBuffer   sb = new StringBuffer  ();
296         sb.append('(');
297         sb.append(getClass().getName());
298         sb.append(" \"");
299         sb.append(getName());
300         sb.append("\" \"");
301         sb.append(getActions());
302         sb.append("\")");
303         return sb.toString();
304     }
305 
306     /**
307      * WriteObject is called to save the state of the ServicePermission to a
308      * stream. The actions are serialized, and the superclass takes care of the
309      * name.
310      */
311     private synchronized void writeObject(java.io.ObjectOutputStream   s)
312             throws IOException   {
313         // Write out the actions. The superclass takes care of the name
314         // call getActions to make sure actions field is initialized
315         if (actions == null)
316             getActions();
317         s.defaultWriteObject();
318     }
319 
320     /**
321      * readObject is called to restore the state of the ServicePermission from a
322      * stream.
323      */
324     private synchronized void readObject(java.io.ObjectInputStream   s)
325             throws IOException  , ClassNotFoundException   {
326         // Read in the action, then initialize the rest
327         s.defaultReadObject();
328         init(getMask(actions));
329     }
330 }
331 /**
332  * A <code>WirePermissionCollection</code> stores a set of <code>WirePermission</code>
333  * permissions.
334  */
335 
336 final class WirePermissionCollection extends PermissionCollection {
337     static final long serialVersionUID = 2617521094909826016L;
338     /**
339      * Table of permissions.
340      * 
341      * @serial
342      */
343     private Hashtable     permissions;
344     /**
345      * Boolean saying if "*" is in the collection.
346      * 
347      * @serial
348      */
349     private boolean     all_allowed;
350 
351     /**
352      * Creates an empty WirePermissionCollection object.
353      *  
354      */
355     public WirePermissionCollection() {
356         permissions = new Hashtable  ();
357         all_allowed = false;
358     }
359 
360     /**
361      * Adds a permission to this PermissionCollection.
362      * 
363      * @param permission The Permission object to add.
364      * 
365      * @throws IllegalArgumentException If the permission is not a
366      *            WirePermission object.
367      * 
368      * @throws SecurityException If this PermissionCollection has been marked
369      *            read-only.
370      */
371     public void add(Permission permission) {
372         if (!(permission instanceof WirePermission))
373             throw new IllegalArgumentException  ("invalid permission: "
374                     + permission);
375         if (isReadOnly())
376             throw new SecurityException  ("attempt to add a Permission to a "
377                     + "readonly PermissionCollection");
378         WirePermission p = (WirePermission) permission;
379         String   name = p.getName();
380         WirePermission existing = (WirePermission) permissions.get(name);
381         if (existing != null) {
382             int oldMask = existing.getMask();
383             int newMask = p.getMask();
384             if (oldMask != newMask) {
385                 permissions.put(name, new WirePermission(name, oldMask
386                         | newMask));
387             }
388         }
389         else {
390             permissions.put(name, permission);
391         }
392         if (!all_allowed) {
393             if (name.equals("*"))
394                 all_allowed = true;
395         }
396     }
397 
398     /**
399      * Determines if a set of permissions implies the permissions expressed in
400      * <code>permission</code>.
401      * 
402      * @param permission The Permission object to compare.
403      * 
404      * @return <code>true</code> if <code>permission</code> is a proper subset of a
405      *         permission in the set; <code>false</code> otherwise.
406      */
407     public boolean implies(Permission permission) {
408         if (!(permission instanceof WirePermission))
409             return false;
410         WirePermission p = (WirePermission) permission;
411         WirePermission x;
412         int desired = p.getMask();
413         int effective = 0;
414         // short circuit if the "*" Permission was added
415         if (all_allowed) {
416             x = (WirePermission) permissions.get("*");
417             if (x != null) {
418                 effective |= x.getMask();
419                 if ((effective & desired) == desired)
420                     return true;
421             }
422         }
423         // strategy:
424         // Check for full match first. Then work our way up the
425         // name looking for matches on a.b.*
426         String   name = p.getName();
427         x = (WirePermission) permissions.get(name);
428         if (x != null) {
429             // we have a direct hit!
430             effective |= x.getMask();
431             if ((effective & desired) == desired)
432                 return true;
433         }
434         // work our way up the tree...
435         int last, offset;
436         offset = name.length() - 1;
437         while ((last = name.lastIndexOf(".", offset)) != -1) {
438             name = name.substring(0, last + 1) + "*";
439             x = (WirePermission) permissions.get(name);
440             if (x != null) {
441                 effective |= x.getMask();
442                 if ((effective & desired) == desired)
443                     return (true);
444             }
445             offset = last - 1;
446         }
447         // we don't have to check for "*" as it was already checked
448         // at the top (all_allowed), so we just return false
449         return false;
450     }
451 
452     /**
453      * Returns an enumeration of all the Permission objects in the container.
454      * 
455      * @return Enumeration of all the Permission objects.
456      */
457     public Enumeration   elements() {
458         return permissions.elements();
459     }
460 }
461
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