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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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/*
 * Copyright 2022 Red Hat, Inc.
 *
 * Licensed 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 under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.wildfly.common.xml;

import org.wildfly.common.annotation.NotNull;

import static javax.xml.XMLConstants.FEATURE_SECURE_PROCESSING;
import static javax.xml.XMLConstants.ACCESS_EXTERNAL_DTD;
import static javax.xml.XMLConstants.ACCESS_EXTERNAL_STYLESHEET;
import static org.wildfly.common.xml.Log.XML_FACTORY_LOGGER;

import javax.xml.XMLConstants;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerFactory;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * Factory provides {@link TransformerFactory} with secure defaults set. Properties not supported generate a warning, but the
 * factory process creation will continue and return a result.
 * Settings based on recommendations of
 * Sonarcloud RSPEC-2755 and
 * OWASP XML
 * External Entity Prevention Cheatsheet.
 * 
 *
 * 

 * {@link javax.xml.XMLConstants#FEATURE_SECURE_PROCESSING} is set to true.
 * {@link javax.xml.XMLConstants#ACCESS_EXTERNAL_DTD} is set to empty.
 * {@link javax.xml.XMLConstants#ACCESS_EXTERNAL_STYLESHEET} is set to empty.
 * 
 *
 * @author Boris Unckel
 * @since 1.6.0.Final
 */
public final class TransformerFactoryUtil {

    /*
     * Prevent recurring log messages (per classloader).
     */
    private static final AtomicBoolean TO_BE_LOGGED = new AtomicBoolean(true);

    @NotNull
    public static TransformerFactory create() {
        final TransformerFactory instance = TransformerFactory.newInstance();
        final boolean toBeLogged = TO_BE_LOGGED.compareAndSet(true, false);

        try {
            instance.setFeature(FEATURE_SECURE_PROCESSING, true);
        } catch (TransformerConfigurationException e) {
            if (toBeLogged) {
                XML_FACTORY_LOGGER.xmlFactoryPropertyNotSupported(e, FEATURE_SECURE_PROCESSING,
                        instance.getClass().getCanonicalName());
            }
        }

        try {
            instance.setAttribute(ACCESS_EXTERNAL_DTD, "");
        } catch (IllegalArgumentException e) {
            if (toBeLogged) {
                XML_FACTORY_LOGGER.xmlFactoryPropertyNotSupported(e, ACCESS_EXTERNAL_DTD,
                        instance.getClass().getCanonicalName());
            }
        }

        try {
            instance.setAttribute(ACCESS_EXTERNAL_STYLESHEET, "");
        } catch (IllegalArgumentException e) {
            if (toBeLogged) {
                XML_FACTORY_LOGGER.xmlFactoryPropertyNotSupported(e, ACCESS_EXTERNAL_STYLESHEET,
                        instance.getClass().getCanonicalName());
            }
        }

        return instance;
    }

    /**
     * No instance.
     */
    private TransformerFactoryUtil() {
        throw new IllegalStateException("No instance");
    }

}