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Java > Open Source Codes > org > apache > ldap > server > db > ScopeEvaluator


1 /*
2  * Copyright 2004 The Apache Software Foundation
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  *
16  */
17
18 /*
19  * $Id: ScopeEvaluator.java,v 1.3 2003/10/15 01:59:46 akarasulu Exp $
20  *
21  * -- (c) LDAPd Group --
22  * -- Please refer to the LICENSE.txt file in the root directory of --
23  * -- any LDAPd project for copyright and distribution information. --
24  *
25  * Created on Oct 9, 2003
26  */
27 package org.apache.ldap.server.db;
28
29
30 import org.apache.ldap.common.filter.ExprNode;
31 import org.apache.ldap.common.filter.ScopeNode;
32 import org.apache.ldap.common.message.DerefAliasesEnum;
33
34 import javax.naming.NamingException JavaDoc;
35 import javax.naming.directory.SearchControls JavaDoc;
36 import java.math.BigInteger JavaDoc;
37
38
39 /**
40  * Evaluates ScopeNode assertions on candidates using a database.
41  *
42  * @author <a HREF="mailto:dev@directory.apache.org">Apache Directory Project</a>
43  * @version $Rev: 169198 $
44  */
45 public class ScopeEvaluator implements Evaluator
46 {
47     /** Database used to evaluate scope with */
48     private Database db;
49
50
51     /**
52      * Creates a scope node evaluator for search expressions.
53      *
54      * @param db the database used to evaluate scope node
55      */
56     public ScopeEvaluator( Database db )
57     {
58         this.db = db;
59     }
60
61
62     /**
63      * @see org.apache.ldap.server.db.Evaluator#evaluate(ExprNode, org.apache.ldap.server.db.IndexRecord)
64      */
65     public boolean evaluate( ExprNode node, IndexRecord record )
66         throws NamingException JavaDoc
67     {
68         ScopeNode snode = ( ScopeNode ) node;
69         
70         switch( snode.getScope() )
71         {
72         case( SearchControls.OBJECT_SCOPE ):
73             String JavaDoc dn = db.getEntryDn( record.getEntryId() );
74             return dn.equals( snode.getBaseDn() );
75         case( SearchControls.ONELEVEL_SCOPE ):
76             return assertOneLevelScope( snode, record.getEntryId() );
77         case( SearchControls.SUBTREE_SCOPE ):
78             return assertSubtreeScope( snode, record.getEntryId() );
79         default:
80             throw new NamingException JavaDoc( "Unrecognized search scope!" );
81         }
82     }
83     
84     
85     /**
86      * Asserts whether or not a candidate has one level scope while taking
87      * alias dereferencing into account.
88      *
89      * @param node the scope node containing the base and alias handling mode
90      * @param id the candidate to assert which can be any db entry's id
91      * @return true if the candidate is within one level scope whether or not
92      * alias dereferencing is enabled.
93      * @throws NamingException if the index lookups fail.
94      */
95     public boolean assertSubtreeScope( final ScopeNode node,
96         final BigInteger JavaDoc id ) throws NamingException JavaDoc
97     {
98         String JavaDoc dn = db.getEntryDn( id );
99         DerefAliasesEnum mode = node.getDerefAliases();
100         Object JavaDoc baseId = db.getEntryId( node.getBaseDn() );
101         boolean isDescendant = dn.endsWith( node.getBaseDn() );
102         
103         /*
104          * The candidate id could be any entry in the db. If search
105          * dereferencing is not enabled then we return the results of the
106          * descendant test.
107          */
108         if ( ! mode.derefInSearching() )
109         {
110             return isDescendant;
111         }
112
113         /*
114          * From here down alias dereferencing is enabled. We determine if the
115          * candidate id is an alias, if so we reject it since aliases should
116          * not be returned.
117          */
118         Index idx = db.getAliasIndex();
119         if ( null != idx.reverseLookup( id ) )
120         {
121             return false;
122         }
123         
124         /*
125          * The candidate is NOT an alias at this point. So if it is a
126          * descendant we just return it since it is in normal subtree scope.
127          */
128         if ( isDescendant )
129         {
130             return true;
131         }
132         
133         /*
134          * At this point the candidate is not a descendant and it is not an
135          * alias. We need to check if the candidate is in extended subtree
136          * scope by performing a lookup on the subtree alias index. This index
137          * stores a tuple mapping the baseId to the ids of objects brought
138          * into subtree scope of the base by an alias:
139          *
140          * ( baseId, aliasedObjId )
141          *
142          * If the candidate id is an object brought into subtree scope then
143          * the lookup returns true accepting the candidate. Otherwise the
144          * candidate is rejected with a false return because it is not in scope.
145          */
146         idx = db.getSubAliasIndex();
147         return idx.hasValue( baseId, id );
148     }
149     
150     
151     /**
152      * Asserts whether or not a candidate has one level scope while taking
153      * alias dereferencing into account.
154      *
155      * @param node the scope node containing the base and alias handling mode
156      * @param id the candidate to assert which can be any db entry's id
157      * @return true if the candidate is within one level scope whether or not
158      * alias dereferencing is enabled.
159      * @throws NamingException if the index lookups fail.
160      */
161     public boolean assertOneLevelScope( final ScopeNode node,
162         final BigInteger JavaDoc id ) throws NamingException JavaDoc
163     {
164         DerefAliasesEnum mode = node.getDerefAliases();
165         Object JavaDoc baseId = db.getEntryId( node.getBaseDn() );
166         Index idx = db.getHierarchyIndex();
167         boolean isChild = idx.hasValue( baseId, id );
168
169         /*
170          * The candidate id could be any entry in the db. If search
171          * dereferencing is not enabled then we return the results of the child
172          * test.
173          */
174         if ( ! mode.derefInSearching() )
175         {
176             return isChild;
177         }
178
179         /*
180          * From here down alias dereferencing is enabled. We determine if the
181          * candidate id is an alias, if so we reject it since aliases should
182          * not be returned.
183          */
184         idx = db.getAliasIndex();
185         if ( null != idx.reverseLookup( id ) )
186         {
187             return false;
188         }
189         
190         /*
191          * The candidate is NOT an alias at this point. So if it is a child we
192          * just return it since it is in normal one level scope.
193          */
194         if ( isChild )
195         {
196             return true;
197         }
198         
199         /*
200          * At this point the candidate is not a child and it is not an alias.
201          * We need to check if the candidate is in extended one level scope by
202          * performing a lookup on the one level alias index. This index stores
203          * a tuple mapping the baseId to the id of objects brought into the
204          * one level scope of the base by an alias: ( baseId, aliasedObjId )
205          * If the candidate id is an object brought into one level scope then
206          * the lookup returns true accepting the candidate. Otherwise the
207          * candidate is rejected with a false return because it is not in scope.
208          */
209         idx = db.getOneAliasIndex();
210         return idx.hasValue( baseId, id );
211     }
212 }
213
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