MessagePolicyInterceptor.java

package xdi2.messaging.container.interceptor.impl;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import xdi2.core.Graph;
import xdi2.core.features.policy.PolicyRoot;
import xdi2.core.features.policy.evaluation.PolicyEvaluationContext;
import xdi2.messaging.Message;
import xdi2.messaging.container.MessagingContainer;
import xdi2.messaging.container.Prototype;
import xdi2.messaging.container.exceptions.Xdi2MessagingException;
import xdi2.messaging.container.exceptions.Xdi2NotAuthorizedException;
import xdi2.messaging.container.execution.ExecutionContext;
import xdi2.messaging.container.execution.ExecutionResult;
import xdi2.messaging.container.interceptor.InterceptorResult;
import xdi2.messaging.container.interceptor.MessageInterceptor;
import xdi2.messaging.container.interceptor.impl.util.MessagePolicyEvaluationContext;

/**
 * This interceptor evaluates message policies.
 * 
 * @author markus
 */
public class MessagePolicyInterceptor extends AbstractInterceptor<MessagingContainer> implements MessageInterceptor, Prototype<MessagePolicyInterceptor> {

	private static Logger log = LoggerFactory.getLogger(MessagePolicyInterceptor.class.getName());

	private Graph messagePolicyGraph; 

	public MessagePolicyInterceptor(Graph messagePolicyGraph) {

		this.messagePolicyGraph = messagePolicyGraph;
	}

	public MessagePolicyInterceptor() {

		this.messagePolicyGraph = null;
	}

	/*
	 * Prototype
	 */

	@Override
	public MessagePolicyInterceptor instanceFor(PrototypingContext prototypingContext) {

		// done

		return this;
	}

	/*
	 * MessageInterceptor
	 */

	@Override
	public InterceptorResult before(Message message, ExecutionContext executionContext, ExecutionResult executionResult) throws Xdi2MessagingException {

		// evaluate the XDI policy of this message

		PolicyRoot policyRoot = message.getPolicyRoot(false);
		boolean policyRootResult = policyRoot == null ? true : this.evaluatePolicyRoot(message, policyRoot, executionContext);
		if (policyRoot != null) if (log.isDebugEnabled()) log.debug("Message " + message + " policy evaluated to " + policyRootResult);

		if (policyRootResult) {

			return InterceptorResult.DEFAULT;
		}

		// done

		throw new Xdi2NotAuthorizedException("Message policy violation for message " + message.toString() + ".", null, executionContext);
	}

	@Override
	public InterceptorResult after(Message message, ExecutionContext executionContext, ExecutionResult executionResult) throws Xdi2MessagingException {

		// done

		return InterceptorResult.DEFAULT;
	}

	/*
	 * Helper methods
	 */

	private boolean evaluatePolicyRoot(Message message, PolicyRoot policyRoot, ExecutionContext executionContext) throws Xdi2MessagingException {

		PolicyEvaluationContext policyEvaluationContext = new MessagePolicyEvaluationContext(message, this.getMessagePolicyGraph(executionContext));

		return policyRoot.evaluate(policyEvaluationContext);
	}

	/*
	 * Getters and setters
	 */

	public Graph getMessagePolicyGraph(ExecutionContext executionContext) {

		Graph messagePolicyGraph = this.getMessagePolicyGraph();
		if (messagePolicyGraph == null) messagePolicyGraph = executionContext.getCurrentGraph();
		if (messagePolicyGraph == null) throw new NullPointerException("No message policy graph.");

		return messagePolicyGraph;
	}

	public Graph getMessagePolicyGraph() {

		return this.messagePolicyGraph;
	}

	public void setMessagePolicyGraph(Graph messagePolicyGraph) {

		this.messagePolicyGraph = messagePolicyGraph;
	}
}