org.fourthline.cling.transport.impl.RecoverGENAEventProcessor.java Source code

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Here is the source code for org.fourthline.cling.transport.impl.RecoverGENAEventProcessor.java

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/*
 * Copyright (C) 2011 4th Line GmbH, Switzerland
 *
 * 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 2 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.fourthline.cling.transport.impl;

import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.lang3.StringEscapeUtils;
import org.apache.commons.lang3.StringUtils;
import org.fourthline.cling.model.message.UpnpMessage;
import org.fourthline.cling.model.message.gena.IncomingEventRequestMessage;
import org.fourthline.cling.transport.spi.UnsupportedDataException;
import org.seamless.xml.XmlPullParserUtils;

/**
 * implementation based on the <em>Xml Pull Parser</em> XML processing API. 
 * <p>
 * This processor try hard to recover broken XML
 * </p>
 * @author Michael Pujos
 */
public class RecoverGENAEventProcessor extends PullGENAEventProcessor {

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

    public void readBody(IncomingEventRequestMessage requestMessage) throws UnsupportedDataException {

        checkRequestBodyValidity(requestMessage);

        try {
            super.readBody(requestMessage);
        } catch (UnsupportedDataException ex) {

            log.warning("bad GENA Event XML found: " + ex);

            // some properties may have been read by the pull parser at this point, so reset the list
            requestMessage.getStateVariableValues().clear();

            String fixedBody = fixXMLEncodedLastChange(
                    XmlPullParserUtils.fixXMLEntities(requestMessage.getBodyString()));
            requestMessage.setBody(UpnpMessage.BodyType.STRING, fixedBody);

            try {
                super.readBody(requestMessage);
                log.info("sucessfully fixed bad GENA XML");
            } catch (UnsupportedDataException ex2) {

                // check if some properties were read
                if (requestMessage.getStateVariableValues().isEmpty()) {
                    // throw the initial exception containing unmodified xml
                    throw ex;
                }

                log.warning("partial read of GENA event properties (probably due to truncated XML)");

            }
        }
    }

    private String fixXMLEncodedLastChange(String xml) {
        Pattern pattern = Pattern.compile("<LastChange>(.*)</LastChange>", Pattern.DOTALL);
        Matcher matcher = pattern.matcher(xml);

        if (matcher.find() && matcher.groupCount() == 1) {

            String xmlEncodedLastChange = matcher.group(1);

            if (XmlPullParserUtils.isNullOrEmpty(xmlEncodedLastChange))
                return xml;

            xmlEncodedLastChange = xmlEncodedLastChange.trim();

            String fixedXmlEncodedLastChange;

            // first look if LastChange text is XML encoded (some renderers will sent it not XML encoded)
            if (xmlEncodedLastChange.charAt(0) == '<') {
                fixedXmlEncodedLastChange = StringEscapeUtils.escapeXml(xmlEncodedLastChange);
                log.warning("fixed LastChange that was not XML encoded");
            } else {
                // delete potential funky characters (at least found in the Philips NP2900 that inserts garbage HTML)
                fixedXmlEncodedLastChange = StringUtils.replaceChars(xmlEncodedLastChange, "<>", null);
                if (fixedXmlEncodedLastChange.equals(xmlEncodedLastChange)) {
                    // no change
                    return xml;
                }

                log.warning("deleted invalid characters in LastChange");
            }

            String fixedXml = "<?xml version=\"1.0\" encoding=\"utf-8\"?>"
                    + "<e:propertyset xmlns:e=\"urn:schemas-upnp-org:event-1-0\">" + "<e:property>" + "<LastChange>"
                    + fixedXmlEncodedLastChange + "</LastChange>" + "</e:property>" + "</e:propertyset>";

            return fixedXml;

        }

        return xml;
    }

}