basicpolicyfindermodule.java

sunxacml源码

/*
 * @(#)BasicPolicyFinderModule.java
 *
 * Copyright 2006 Sun Microsystems, Inc. All Rights Reserved.
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 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
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package com.sun.xacml.support.finder;

import com.sun.xacml.AbstractPolicy;
import com.sun.xacml.EvaluationCtx;
import com.sun.xacml.PolicyMetaData;
import com.sun.xacml.PolicyReference;
import com.sun.xacml.VersionConstraints;

import com.sun.xacml.combine.PolicyCombiningAlgorithm;

import com.sun.xacml.finder.PolicyFinder;
import com.sun.xacml.finder.PolicyFinderModule;
import com.sun.xacml.finder.PolicyFinderResult;

import java.net.URI;

import java.util.logging.Level;
import java.util.logging.Logger;


/**
 * This is a basic implementation of <code>PolicyFinderModule</code> that
 * accepts already created <code>AbstractPolicy</code>s and supports
 * finding by context and reference. All policies are held forever once
 * added to this module, and cannot be refreshed or removed. New policies
 * may be added at any point. You may optionally specify a combining
 * algorithm to use when more than one applicable policy is found, and then
 * a new PolicySet is wrapped around the policies using this algorithm. If
 * no combining algorithm is provided, then an error is returned if more
 * than one policy matches.
 * <p>
 * This module is provided as an example, but is still fully functional, and
 * should be useful for many simple applications. This is provided in the
 * <code>support</code> package rather than the core codebase because it
 * implements non-standard behavior.
 *
 * @since 2.0
 * @author Seth Proctor
 */
public class BasicPolicyFinderModule extends PolicyFinderModule
{

    // the collections used to handle both kinds of policies
    private PolicyCollection ctxPolicies;
    private PolicyCollection refPolicies;

    // the combining alg, or null if none is used
    private PolicyCombiningAlgorithm combiningAlg;

    // the policy identifier for any policy sets we dynamically create
    private static final String POLICY_ID =
        "urn:com:sun:xacml:support:finder:dynamic-policy-set";
    private static URI policyId = null;

    // the logger we'll use for all messages
    private static final Logger logger =
        Logger.getLogger(BasicPolicyFinderModule.class.getName());

    static {
        try {
            policyId = new URI(POLICY_ID);
        } catch (Exception e) {
            // this can't actually happen, but just in case...
            if (logger.isLoggable(Level.SEVERE))
                logger.log(Level.SEVERE, "couldn't assign default policy id");
        }
    };

    /**
     * Creates a <code>BasicPolicyFinderModule</code>.
     */
    public BasicPolicyFinderModule() {
        ctxPolicies = new PolicyCollection();
        refPolicies = new PolicyCollection();
    }

    /**
     * Creates a <code>BasicPolicyFinderModule</code> that can combine
     * multiple applicable policies under a single, dynamic PolicySet.
     *
     * @param combiningAlg the algorithm to use in a new PolicySet when more
     *                     than one policy applies
     */
    public BasicPolicyFinderModule(PolicyCombiningAlgorithm combiningAlg) {
        ctxPolicies = new PolicyCollection(combiningAlg, policyId);
        refPolicies = new PolicyCollection(combiningAlg, policyId);
    }

    /**
     * Adds a policy that will be available both by reference and by
     * matching to a context. The policy's identifier is used for finding
     * by reference. If a policy with the same identifier and version is
     * already handled by this module, then the policy is not added.
     *
     * @param policy the policy to add
     *
     * @return true if the policy was added, false otherwise
     */
    public synchronized boolean addPolicy(AbstractPolicy policy) {
        if (ctxPolicies.addPolicy(policy))
            return refPolicies.addPolicy(policy);
        else
            return false;
    }

    /**
     * Adds a policy that will be available only by matching to a context.
     * If a policy with the same identifier and version is already handled
     * by this module, then the policy is not added.
     *
     * @param policy the policy to add
     *
     * @return true if the policy was added, false otherwise
     */
    public synchronized boolean addPolicyNoRef(AbstractPolicy policy) {
        return ctxPolicies.addPolicy(policy);
    }

    /**
     * Adds a policy that will be available only by reference. The policy's
     * identifier is used for finding by reference. If a policy with the
     * same identifier and version is already handled by this module, then
     * the policy is not added.
     *
     * @param policy the policy to add
     *
     * @return true if the policy was added, false otherwise
     */
    public synchronized boolean addPolicyOnlyRef(AbstractPolicy policy) {
        return refPolicies.addPolicy(policy);
    }

    /**
     * Always returns <code>true</code> since this module does support
     * finding policies based on context matching.
     *
     * @return true
     */
    public boolean isRequestSupported() {
        return true;
    }

    /**
     * Always returns <code>true</code> since this module does support
     * finding policies based on reference.
     *
     * @return true
     */
    public boolean isIdReferenceSupported() {
        return true;
    }

    /**
     * Initialize this module. Typically this is called by
     * <code>PolicyFinder</code> when a PDP is created.
     *
     * @param finder the <code>PolicyFinder</code> using this module
     */
    public void init(PolicyFinder finder) {
        // we don't need to do anything here
    }

    /**
     * Finds a policy based on a request's context. If more than one policy
     * matches, then this either returns an error or a new policy wrapping
     * the multiple policies (depending on which constructor was used to
     * construct this instance).
     *
     * @param context the representation of the request data
     *
     * @return the result of trying to find an applicable policy
     */
    public PolicyFinderResult findPolicy(EvaluationCtx context) {
        try {
            AbstractPolicy policy = ctxPolicies.getPolicy(context);

            if (policy == null)
                return new PolicyFinderResult();
            else
                return new PolicyFinderResult(policy);
        } catch (TopLevelPolicyException tlpe) {
            return new PolicyFinderResult(tlpe.getStatus());
        }
    }

    /**
     * Attempts to find a policy by reference, based on the provided
     * parameters.
     *
     * @param idReference an identifier specifying some policy
     * @param type type of reference (policy or policySet) as identified by
     *             the fields in <code>PolicyReference</code>
     * @param constraints any optional constraints on the version of the
     *                    referenced policy (this will never be null, but
     *                    it may impose no constraints, and in fact will
     *                    never impose constraints when used from a pre-2.0
     *                    XACML policy)
     * @param parentMetaData the meta-data from the parent policy, which
     *                       provides XACML version, factories, etc.
     *
     * @return the result of looking for a matching policy
     */
    public PolicyFinderResult findPolicy(URI idReference, int type,
                                         VersionConstraints constraints,
                                         PolicyMetaData parentMetaData) {
        AbstractPolicy policy =
            refPolicies.getPolicy(idReference.toString(), type, constraints);

        if (policy == null)
            return new PolicyFinderResult();
        else
            return new PolicyFinderResult(policy);
    }

}