source: fedd/abac-src/rbtm/engine/AbstractProofNode.java @ 866c983

axis_examplecompt_changesinfo-opsversion-1.30version-2.00version-3.01version-3.02
Last change on this file since 866c983 was 8780cbec, checked in by Jay Jacobs <Jay.Jacobs@…>, 15 years ago

ABAC sources from Cobham

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1package edu.stanford.peer.rbtm.engine;
2
3import java.util.*;
4
5import edu.stanford.peer.rbtm.credential.*;
6import edu.stanford.peer.rbtm.util.*;
7
8/**
9 * The parent class of all proof nodes. This is the base class which contains
10 * default implementations of all common methods.
11 */
12public abstract class AbstractProofNode implements ProofNode
13{
14    // The following two fields can't be changed by other classes. 
15    // If subclasses need to access them, use get methods
16
17    /** The EntityExpression this node is about. */
18    EntityExpression   _roleExp; 
19   
20    /**
21     * The proof _graph this node is in, this reference is used while
22     * processing this node
23     */
24    ProofGraph       _graph;
25
26    /** Processing mode for subclassed node types */
27    public final boolean addRole = true;
28   
29    /** Nodes that can reach this node directly, evidences are credentials. */
30    protected ResultEvidenceMap  parents;
31
32    /** Nodes that this node can reach directly, evidecens are credentials. */
33    protected ResultEvidenceMap  children; 
34
35        /** Backward solutions on this node  */
36    protected ResultEvidenceMap  backwardSolutions;
37
38        /** Forward solutions on this node */
39    protected ResultEvidenceMap  forwardSolutions;
40
41    protected ArrayList  backwardListeners;
42    protected ArrayList  forwardListeners;
43
44    boolean backwardProcessed;
45    boolean forwardProcessed;
46
47    AbstractProofNode (ProofGraph graph, EntityExpression re, int trackType)
48    {
49        _graph = graph;
50        _roleExp = re;
51        Debug.debugInfo("A new node is created for " + re);
52
53        parents = new ResultEvidenceMap(trackType); 
54        children = new ResultEvidenceMap(trackType); 
55        backwardSolutions = new ResultEvidenceMap(trackType);
56        forwardSolutions = new ResultEvidenceMap(trackType);
57       
58        backwardListeners = new ArrayList(10);
59        forwardListeners = new ArrayList(10);
60    }
61
62    public ProofGraph getGraph() {
63        return _graph;
64    }
65   
66    public EntityExpression getRoleExp() {
67        return _roleExp;
68    }
69   
70    public ResultEvidenceMap getForwardSolutions() {
71        return forwardSolutions;
72    }
73   
74    public ResultEvidenceMap getBackwardSolutions() {
75        return backwardSolutions;
76    }
77   
78    public ResultEvidenceMap getChildren() {
79        return children;
80    }
81   
82    public ResultEvidenceMap getParents() {
83        return parents;
84    }
85   
86    /**
87     * A single iteration of evidence gathering. This recursive method is
88     * polymorphic and may be extended in child proof node implementations.
89     * @param size the size of the evidence set (of credentials)
90     * @param target the parent expression to be found in the cred graph
91     */
92    public HashSet getChain(int size, EntityExpression target) {
93        return new HashSet(size);
94    }
95
96
97    public void invalidateForward() {
98        Debug.debugInfo("Invalidate forward result on " + this);
99        if(forwardProcessed) {
100            forwardProcessed = false;
101            //reuse the credential and update the forward search
102            getGraph().addForwardNode(getRoleExp());
103        }
104    }
105
106    public void invalidateBackward() {
107        Debug.debugInfo("Invalidate backward result on " + this);
108        if(backwardProcessed) {
109            backwardProcessed = false;
110            //reuse the credential and update the backward search
111            getGraph().addBackwardNode(getRoleExp());
112        }
113    }
114
115    public void backwardProcess() {
116        if (backwardProcessed) { return; }
117        Predicate p = getGraph().getPredicate();
118        EntityExpression expr = getRoleExp();
119        Debug.debugInfo("Backward processing " + this);
120        if(p == null) { // cred mgr has null predicate
121            // backwards compatibility for credential manager
122            backwardSolutionAdded(this, expr);
123            additionalBackwardProcess();
124        }
125        else {
126            if(p.test(expr)) { 
127                // add this expression to the soln and stop
128                backwardSolutionAdded(this, expr);
129            } else {   
130                // skip this soln and continue processing
131                additionalBackwardProcess();
132            }
133        }
134        backwardProcessed = true;
135    }
136   
137    // The method that does the work when we visit a node
138    public void forwardProcess() 
139    {
140        if (forwardProcessed) {
141            return;
142        }
143       
144        // first step: go over all credentials that have this as subject
145        Debug.debugInfo("Forward processing " + this);
146        Iterator  credIt = _graph.findCredentialsBySubject(_roleExp);
147        while (credIt.hasNext()) { 
148            StaticCredential credential = (StaticCredential) credIt.next();
149            Debug.debugInfo("Find one credential: " + credential);
150            ProofNode node = _graph.addForwardNode(credential.getDefinedRole());
151            node.addParent(this, credential);
152            //_graph.addProofEdge(this, node, credential);
153        }
154       
155                  additionalForwardProcess();
156                  forwardProcessed = true;
157                 
158                  // second step: find partial solutions which match this node's
159                  //              role expression, unless its an intersection
160                  if (_roleExp instanceof Intersection) { return;       }
161                  credIt = _graph.findCredentialsByPartialSubject(_roleExp);
162                  while (credIt.hasNext()) { 
163                                StaticCredential credential = (StaticCredential) credIt.next();
164                                ProofNode node = _graph.addForwardNode(credential.getSubject());
165                                node.backwardProcess();
166                                // Forward discovery of roles
167                                //
168                                // This is not reuired according to the algorithm from
169                                // "Distributed Credential Chain Discovery in Trust Management"
170                                // in JCS but is needed for credential discovery in ATN where
171                                // forward search takes place from sensitive roles.
172                                node.forwardProcess();
173                                //int j =
174                                //((Intersection) credential.getSubject()).getIndexOf(_roleExp);
175                                //forward.solutionAdded(new PartialSolution(_roleExp, j));
176                  }
177    }
178   
179    abstract protected void additionalForwardProcess();
180    abstract protected void additionalBackwardProcess();
181   
182   
183    public void addBackwardListener(BackwardSolutionListener sl) {
184        Debug.debugInfo(sl + " is now listening on " + this + 
185                        " for backward solutions");
186        backwardListeners.add(sl);
187        propagateBackwardSolutionsTo(sl);
188    }
189   
190    public void addForwardListener(ForwardSolutionListener sl) {
191        Debug.debugInfo(sl + " is now listening on " + this + 
192                        " for forward solutions");
193        forwardListeners.add(sl);
194        propagateForwardSolutionsTo(sl);
195    }
196   
197    /**
198     * Add a node as a parent to this node
199     * @param  node: the parent node
200     */
201    public void addParent(ProofNode node, Object evidence) {
202        if (parents.putResultEvidence(node.getRoleExp(), evidence)) { 
203            addForwardListener(node);
204        }
205    }
206   
207    public void addChild(ProofNode node, Object evidence) {
208        if (children.putResultEvidence(node.getRoleExp(), evidence)) { 
209            addBackwardListener(node);
210        }
211    }
212   
213    public void backwardSolutionAdded(ProofNode s, BackwardSolution r)
214    {
215        if (backwardSolutions.putResultEvidence(r, s)) {   
216            // when solution r is new
217            Debug.debugInfo("Backward solution added to: " + this + 
218                            " from: " + s + " value: " + r);
219            propagateBackwardSolution(r);
220        }
221    }
222   
223    public void forwardSolutionAdded(ProofNode s, ForwardSolution r) {
224        /*
225       if (r instanceof PartialSolution) {
226            Intersection re = r.getIntersection();
227            Integer index = r.getNumber();
228            HashMap value = (HashMap) partialSols.get(re);
229            if (value == null) {   // first piece
230                value = new HashMap();
231                partialSols.put(re, value);
232            }
233            SmallSet evidences = value.get(index);
234            if (evidences == null) { // A new piece
235                evidences = new SmallSet(s);
236                value.put(index, evidences);
237                if (value.size() == re.getK()) { // have all pieces
238                    // Add an edge from current node to re
239                    // addEdge();
240                }
241            } else if (trackAll) {
242                evidences.add(s);
243            }
244                        return;
245        }
246        */
247        if (forwardSolutions.putResultEvidence(r, s)) {
248            Debug.debugInfo("Forward solution added to: " + this + 
249                            " from: " + s + " value: " + r);
250            propagateForwardSolution(r);
251        }
252    }
253
254    /** propagate backward solutions to all listening nodes. */
255    protected void propagateBackwardSolutionsTo(BackwardSolutionListener listener)
256    {
257        Object[] sols = backwardSolutions.resultSet().toArray();
258        for (int i=0; i<sols.length; i++) {
259            listener.backwardSolutionAdded(this, (BackwardSolution)(sols[i]));
260        }
261    }
262   
263    protected void propagateForwardSolutionsTo(ForwardSolutionListener listener)
264    {
265        Object[] sols = forwardSolutions.resultSet().toArray();
266        for (int i=0; i<sols.length; i++) {
267            listener.forwardSolutionAdded(this, (ForwardSolution)(sols[i]));
268        }
269    }
270   
271    protected void propagateBackwardSolution(BackwardSolution g)
272    {
273        Object[] listeners = backwardListeners.toArray();
274        for (int i=0; i<listeners.length; i++) {
275            ((BackwardSolutionListener)listeners[i]).backwardSolutionAdded(this, g);
276        }
277    }
278   
279    protected void propagateForwardSolution(ForwardSolution g)
280    {
281        Object[] listeners = forwardListeners.toArray();
282        for (int i=0; i<listeners.length; i++) {
283            ((ForwardSolutionListener)listeners[i]).forwardSolutionAdded(this, g);
284        }
285    }
286   
287    public String toString() 
288    {
289                  return "node " + _roleExp;
290    }
291   
292
293    // boolean hasParent(ProofNode node) { return parents.containsResult(node._roleExp); }
294
295
296        //////////// code for SelectiveProofNode
297    /*
298     * The following two fields store desired goals.  Only desired goals are
299     * passed through edges.  Setting them to null means all goals are
300     * desired.
301     * In backward search, if child A.r only wants to see one solution, while
302     * child A.r1.r2 wants to see all solutions.  All goals are desired, so
303     * they are passed to A.r as well.  But A.r should have only one desired
304     * solution, and so A.r will not propagate them further.
305     */
306    // SmallSet  backwardGoals = new SmallSet();
307    // SmallSet  forwardGoals = new SmallSet();
308
309    /*
310    void enableBackwardGoal(EntityExpression g)
311    {
312        if (backwardGoals != null && ! backwardGoals.containsGoal(g)) {
313                // has not been enabled before
314            backwardGoals.addGoal(g);
315            if (backwardSoltuions.containsResult(g)) {
316                        propagateBackwardSolution(g);
317            }
318            // Enable this backward goal for all parents
319            Object[] list = parents.toArray();  // inform listeners
320            for (int i=0; i<list.length; i++) {
321                ((ProofNode)list[i]).enableBackwardGoal(g);
322            }
323        }
324    }
325
326    void enableAllBackwardGoals()
327    {
328        if (backwardGoals == null ) {
329            backwardGoals = null;
330            // if have been procesed, loop over all parents, and enable them
331            // if haven't been processed, just enable it
332        }
333    }
334    */
335} // End of class ProofNode
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