/*
* @(#)DenyOverridesPolicyAlg.java
*
* Copyright 2003-2005 Sun Microsystems, Inc. All Rights Reserved.
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* This software is provided "AS IS," without a warranty of any kind. ALL
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package com.sun.xacml.combine;
import java.net.URI;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import com.sun.xacml.AbstractPolicy;
import com.sun.xacml.EvaluationCtx;
import com.sun.xacml.MatchResult;
import com.sun.xacml.Obligation;
import com.sun.xacml.ctx.Result;
/**
* This is the standard Deny Overrides policy combining algorithm. It allows a single evaluation of
* Deny to take precedence over any number of permit, not applicable or indeterminate results. Note
* that since this implementation does an ordered evaluation, this class also supports the Ordered
* Deny Overrides algorithm.
*
* @since 1.0
* @author Seth Proctor
*
* Adding generic type support by Christian Mueller (geotools)
*/
public class DenyOverridesPolicyAlg extends PolicyCombiningAlgorithm {
/**
* The standard URN used to identify this algorithm
*/
public static final String algId = "urn:oasis:names:tc:xacml:1.0:policy-combining-algorithm:"
+ "deny-overrides";
// a URI form of the identifier
private static final URI identifierURI = URI.create(algId);
/**
* Standard constructor.
*/
public DenyOverridesPolicyAlg() {
super(identifierURI);
}
/**
* Protected constructor used by the ordered version of this algorithm.
*
* @param identifier
* the algorithm's identifier
*/
protected DenyOverridesPolicyAlg(URI identifier) {
super(identifier);
}
/**
* Applies the combining rule to the set of policies based on the evaluation context.
*
* @param context
* the context from the request
* @param parameters
* a (possibly empty) non-null <code>List</code> of <code>CombinerParameter<code>s
* @param policyElements
* the policies to combine
*
* @return the result of running the combining algorithm
*/
public Result combine(EvaluationCtx context, List<CombinerParameter> parameters,
List<? extends CombinerElement> policyElements) {
boolean atLeastOnePermit = false;
Set<Obligation> permitObligations = new HashSet<Obligation>();
Iterator<? extends CombinerElement> it = policyElements.iterator();
while (it.hasNext()) {
AbstractPolicy policy = ((PolicyCombinerElement) (it.next())).getPolicy();
// make sure that the policy matches the context
MatchResult match = policy.match(context);
if (match.getResult() == MatchResult.INDETERMINATE)
return new Result(Result.DECISION_DENY, context.getResourceId().encode());
if (match.getResult() == MatchResult.MATCH) {
// evaluate the policy
Result result = policy.evaluate(context);
int effect = result.getDecision();
// unlike in the RuleCombining version of this alg, we always
// return DENY if any Policy returns DENY or INDETERMINATE
if ((effect == Result.DECISION_DENY) || (effect == Result.DECISION_INDETERMINATE))
return new Result(Result.DECISION_DENY, context.getResourceId().encode(),
result.getObligations());
// remember if at least one Policy said PERMIT
if (effect == Result.DECISION_PERMIT) {
atLeastOnePermit = true;
permitObligations.addAll(result.getObligations());
}
}
}
// if we got a PERMIT, return it, otherwise it's NOT_APPLICABLE
if (atLeastOnePermit)
return new Result(Result.DECISION_PERMIT, context.getResourceId().encode(),
permitObligations);
else
return new Result(Result.DECISION_NOT_APPLICABLE, context.getResourceId().encode());
}
}