src/main/java/org/apache/sling/xss/impl/PolicyHandler.java

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 * Licensed to the Apache Software Foundation (ASF) under one or
 * more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding
 * copyright ownership. The ASF licenses this file to you under the
 * Apache License, Version 2.0 (the "License"); you may not use
 * this file except in compliance with the License. You may obtain
 * a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0 Unless required by
 * applicable law or agreed to in writing, software distributed
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 * See the License for the specific language governing permissions
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package org.apache.sling.xss.impl;

import java.io.IOException;
import java.io.InputStream;

import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.resource.ResourceResolverFactory;
import org.owasp.validator.html.AntiSamy;
import org.owasp.validator.html.Policy;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Class that provides the capability of securing input provided as plain text for
 * HTML output.
 */
public class PolicyHandler {

    /**
     * Logger
     */
    private static final Logger LOGGER = LoggerFactory.getLogger(PolicyHandler.class);

    private Policy policy;

    private AntiSamy antiSamy;

    /**
     * Try to load a policy from the given relative path.
     */
    public PolicyHandler(final ResourceResolverFactory factory, final String policyPath) throws Exception {
        final ResourceResolver resolver = factory.getAdministrativeResourceResolver(null);
        try {
            final Resource rsrc = resolver.getResource(policyPath);
            if (rsrc == null) {
                throw new IllegalArgumentException("Could not resolve '" + policyPath + " to a valid policy resource.");
            }
            LOGGER.debug("Loading policy from '{}'.", rsrc.getPath());

            InputStream policyStream = null;
            // fix for classloader issue with IBM JVM: see bug #31946
            // (currently: http://bugs.day.com/bugzilla/show_bug.cgi?id=31946)
            Thread currentThread = Thread.currentThread();
            ClassLoader cl = currentThread.getContextClassLoader();
            try {
                currentThread.setContextClassLoader(this.getClass().getClassLoader());
                policyStream = rsrc.adaptTo(InputStream.class);
                this.policy = Policy.getInstance(policyStream);
                this.antiSamy = new AntiSamy(this.policy);
            } finally {
                if (policyStream != null) {
                    try {
                        policyStream.close();
                    } catch (final IOException ioe) {
                        // ignored as we can't do anything about this (besides logging)
                    }
                }
                currentThread.setContextClassLoader(cl);
            }
        } finally {
            resolver.close();
        }
    }

    public Policy getPolicy() {
        return this.policy;
    }

    public AntiSamy getAntiSamy() {
        return this.antiSamy;
    }
}