org.xacml4j.v30.spi.pip.DefaultPolicyInformationPoint.java Source code

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Here is the source code for org.xacml4j.v30.spi.pip.DefaultPolicyInformationPoint.java

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package org.xacml4j.v30.spi.pip;

/*
 * #%L
 * Xacml4J Core Engine Implementation
 * %%
 * Copyright (C) 2009 - 2014 Xacml4J.org
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/lgpl-3.0.html>.
 * #L%
 */

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Node;
import org.xacml4j.v30.AttributeDesignatorKey;
import org.xacml4j.v30.BagOfAttributeExp;
import org.xacml4j.v30.CategoryId;
import org.xacml4j.v30.EvaluationContext;
import org.xacml4j.v30.EvaluationException;

import com.google.common.base.Preconditions;
import com.google.common.collect.Iterables;

/**
 * A default implementation of {@link PolicyInformationPoint}
 *
 * @author Giedrius Trumpickas
 */
public class DefaultPolicyInformationPoint implements PolicyInformationPoint {
    private final static Logger log = LoggerFactory.getLogger(DefaultPolicyInformationPoint.class);

    private String id;
    private PolicyInformationPointCacheProvider cache;
    private ResolverRegistry registry;

    public DefaultPolicyInformationPoint(String id, ResolverRegistry resolvers,
            PolicyInformationPointCacheProvider cache) {
        Preconditions.checkNotNull(id);
        Preconditions.checkNotNull(resolvers);
        Preconditions.checkNotNull(cache);
        this.id = id;
        this.cache = cache;
        this.registry = resolvers;
    }

    @Override
    public String getId() {
        return id;
    }

    @Override
    public BagOfAttributeExp resolve(final EvaluationContext context, AttributeDesignatorKey ref) throws Exception {
        if (log.isDebugEnabled()) {
            log.debug("Trying to resolve designator=\"{}\"", ref);
        }
        Iterable<AttributeResolver> resolvers = registry.getMatchingAttributeResolvers(context, ref);
        if (Iterables.isEmpty(resolvers)) {
            if (log.isDebugEnabled()) {
                log.debug("No matching resolver found for designator=\"{}\"", ref);
            }
            return null;
        }
        for (AttributeResolver r : resolvers) {
            AttributeResolverDescriptor d = r.getDescriptor();
            Preconditions.checkState(d.canResolve(ref));
            ResolverContext rContext = createContext(context, d);
            AttributeSet attributes = null;
            if (d.isCacheable()) {
                if (log.isDebugEnabled()) {
                    log.debug("Trying to find resolver id=\"{}\" values in cache", d.getId());
                }
                attributes = cache.getAttributes(rContext);
                if (attributes != null && !isExpired(attributes, context)) {
                    if (log.isDebugEnabled()) {
                        log.debug("Found cached resolver id=\"{}\" values=\"{}\"", d.getId(), attributes);
                    }
                    return attributes.get(ref.getAttributeId());
                }
            }
            try {
                if (log.isDebugEnabled()) {
                    log.debug("Trying to resolve values with resolver id=\"{}\"", d.getId());
                }
                attributes = r.resolve(rContext);
                if (attributes.isEmpty()) {
                    if (log.isDebugEnabled()) {
                        log.debug("Resolver id=\"{}\" failed to resolve attributes", d.getId());
                    }
                    continue;
                }
                if (log.isDebugEnabled()) {
                    log.debug("Resolved attributes=\"{}\"", attributes);
                }
            } catch (Exception e) {
                if (log.isDebugEnabled()) {
                    log.debug("Resolver id=\"{}\" failed to resolve attributes", d.getId(), e);
                }
                continue;
            }
            // check if resolver
            // descriptor allows long term caching
            if (d.isCacheable() && !attributes.isEmpty()) {
                cache.putAttributes(rContext, attributes);
            }
            context.setDecisionCacheTTL(d.getPreferredCacheTTL());
            return attributes.get(ref.getAttributeId());
        }
        return ref.getDataType().emptyBag();
    }

    private boolean isExpired(AttributeSet v, EvaluationContext context) {
        return ((context.getTicker().read() - v.getCreatedTime()) / 1000000000L) >= v.getDescriptor()
                .getPreferredCacheTTL();
    }

    private boolean isExpired(Content v, EvaluationContext context) {
        long duration = context.getTicker().read() - v.getTimestamp() / 1000000000L;

        if (log.isDebugEnabled()) {
            log.debug("Attribute set=\"{}\" age=\"{}\" in cache", v, duration);
        }
        return duration >= v.getDescriptor().getPreferredCacheTTL();
    }

    @Override
    public Node resolve(final EvaluationContext context, CategoryId category) throws Exception {
        ContentResolver r = registry.getMatchingContentResolver(context, category);
        if (r == null) {
            return null;
        }
        ContentResolverDescriptor d = r.getDescriptor();
        ResolverContext pipContext = createContext(context, d);
        Content v = null;
        if (d.isCacheable()) {
            v = cache.getContent(pipContext);
            if (v != null && !isExpired(v, context)) {
                if (log.isDebugEnabled()) {
                    log.debug("Found cached content=\"{}\"", v);
                }
                return v.getContent();
            }
        }
        try {
            v = r.resolve(pipContext);
        } catch (Exception e) {
            if (log.isDebugEnabled()) {
                log.debug("Received error while resolving content for category=\"{}\"", category, e);
            }
            return null;
        }
        if (d.isCacheable()) {
            cache.putContent(pipContext, v);
        }
        context.setDecisionCacheTTL(d.getPreferredCacheTTL());
        return v.getContent();
    }

    @Override
    public ResolverRegistry getRegistry() {
        return registry;
    }

    private ResolverContext createContext(EvaluationContext context, ResolverDescriptor d)
            throws EvaluationException {
        return new DefaultResolverContext(context, d);
    }
}