/*
* Copyright 2004 Sun Microsystems, 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 com.sun.syndication.io;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;
import org.jdom.Document;
import org.jdom.JDOMException;
import org.jdom.input.DOMBuilder;
import org.jdom.input.JDOMParseException;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;
import org.xml.sax.XMLReader;
import com.sun.syndication.feed.WireFeed;
import com.sun.syndication.io.impl.FeedParsers;
import com.sun.syndication.io.impl.XmlFixerReader;
/**
* Parses an XML document (File, InputStream, Reader, W3C SAX InputSource, W3C DOM Document or JDom DOcument)
* into an WireFeed (RSS/Atom).
* <p>
* It accepts all flavors of RSS (0.90, 0.91, 0.92, 0.93, 0.94, 1.0 and 2.0) and
* Atom 0.3 feeds. Parsers are plugable (they must implement the WireFeedParser interface).
* <p>
* The WireFeedInput useds liberal parsers.
* <p>
* @author Alejandro Abdelnur
*
*/
public class WireFeedInput {
private static Map clMap = new WeakHashMap();
private static FeedParsers getFeedParsers() {
synchronized(WireFeedInput.class) {
FeedParsers parsers = (FeedParsers)
clMap.get(Thread.currentThread().getContextClassLoader());
if (parsers == null) {
parsers = new FeedParsers();
clMap.put(Thread.currentThread().getContextClassLoader(), parsers);
}
return parsers;
}
}
private static final InputSource EMPTY_INPUTSOURCE = new InputSource(new ByteArrayInputStream(new byte[0]));
private static final EntityResolver RESOLVER = new EmptyEntityResolver();
private static class EmptyEntityResolver implements EntityResolver {
public InputSource resolveEntity(String publicId, String systemId) {
if(systemId != null && systemId.endsWith(".dtd")) return EMPTY_INPUTSOURCE;
return null;
}
}
private boolean _validate;
private boolean _xmlHealerOn;
/**
* Returns the list of supported input feed types.
* <p>
* @see WireFeed for details on the format of these strings.
* <p>
* @return a list of String elements with the supported input feed types.
*
*/
public static List getSupportedFeedTypes() {
return getFeedParsers().getSupportedFeedTypes();
}
/**
* Creates a WireFeedInput instance with input validation turned off.
* <p>
*
*/
public WireFeedInput() {
this (false);
}
/**
* Creates a WireFeedInput instance.
* <p>
* @param validate indicates if the input should be validated. NOT IMPLEMENTED YET (validation does not happen)
*
*/
public WireFeedInput(boolean validate) {
_validate = false; // TODO FIX THIS THINGY
_xmlHealerOn = true;
}
/**
* Enables XML healing in the WiredFeedInput instance.
* <p>
* Healing trims leading chars from the stream (empty spaces and comments) until the XML prolog.
* <p>
* Healing resolves HTML entities (from literal to code number) in the reader.
* <p>
* The healing is done only with the build(File) and build(Reader) signatures.
* <p>
* By default is TRUE.
* <p>
* @param heals TRUE enables stream healing, FALSE disables it.
*
*/
public void setXmlHealerOn(boolean heals) {
_xmlHealerOn = heals;
}
/**
* Indicates if the WiredFeedInput instance will XML heal (if necessary) the character stream.
* <p>
* Healing trims leading chars from the stream (empty spaces and comments) until the XML prolog.
* <p>
* Healing resolves HTML entities (from literal to code number) in the reader.
* <p>
* The healing is done only with the build(File) and build(Reader) signatures.
* <p>
* By default is TRUE.
* <p>
* @return TRUE if healing is enabled, FALSE if not.
*
*/
public boolean getXmlHealerOn() {
return _xmlHealerOn;
}
/**
* Builds an WireFeed (RSS or Atom) from a file.
* <p>
* NOTE: This method delages to the 'AsbtractFeed WireFeedInput#build(org.jdom.Document)'.
* <p>
* @param file file to read to create the WireFeed.
* @return the WireFeed read from the file.
* @throws FileNotFoundException thrown if the file could not be found.
* @throws IOException thrown if there is problem reading the file.
* @throws IllegalArgumentException thrown if feed type could not be understood by any of the underlying parsers.
* @throws FeedException if the feed could not be parsed
*
*/
public WireFeed build(File file) throws FileNotFoundException,IOException,IllegalArgumentException,FeedException {
WireFeed feed;
Reader reader = new FileReader(file);
if (_xmlHealerOn) {
reader = new XmlFixerReader(reader);
}
feed = build(reader);
reader.close();
return feed;
}
/**
* Builds an WireFeed (RSS or Atom) from an Reader.
* <p>
* NOTE: This method delages to the 'AsbtractFeed WireFeedInput#build(org.jdom.Document)'.
* <p>
* @param reader Reader to read to create the WireFeed.
* @return the WireFeed read from the Reader.
* @throws IllegalArgumentException thrown if feed type could not be understood by any of the underlying parsers.
* @throws FeedException if the feed could not be parsed
*
*/
public WireFeed build(Reader reader) throws IllegalArgumentException,FeedException {
SAXBuilder saxBuilder = createSAXBuilder();
try {
if (_xmlHealerOn) {
reader = new XmlFixerReader(reader);
}
Document document = saxBuilder.build(reader);
return build(document);
}
catch (JDOMParseException ex) {
throw new ParsingFeedException("Invalid XML: " + ex.getMessage(), ex);
}
catch (IllegalArgumentException ex) {
throw ex;
}
catch (Exception ex) {
throw new ParsingFeedException("Invalid XML",ex);
}
}
/**
* Builds an WireFeed (RSS or Atom) from an W3C SAX InputSource.
* <p>
* NOTE: This method delages to the 'AsbtractFeed WireFeedInput#build(org.jdom.Document)'.
* <p>
* @param is W3C SAX InputSource to read to create the WireFeed.
* @return the WireFeed read from the W3C SAX InputSource.
* @throws IllegalArgumentException thrown if feed type could not be understood by any of the underlying parsers.
* @throws FeedException if the feed could not be parsed
*
*/
public WireFeed build(InputSource is) throws IllegalArgumentException,FeedException {
SAXBuilder saxBuilder = createSAXBuilder();
try {
Document document = saxBuilder.build(is);
return build(document);
}
catch (JDOMParseException ex) {
throw new ParsingFeedException("Invalid XML: " + ex.getMessage(), ex);
}
catch (IllegalArgumentException ex) {
throw ex;
}
catch (Exception ex) {
throw new ParsingFeedException("Invalid XML",ex);
}
}
/**
* Builds an WireFeed (RSS or Atom) from an W3C DOM document.
* <p>
* NOTE: This method delages to the 'AsbtractFeed WireFeedInput#build(org.jdom.Document)'.
* <p>
* @param document W3C DOM document to read to create the WireFeed.
* @return the WireFeed read from the W3C DOM document.
* @throws IllegalArgumentException thrown if feed type could not be understood by any of the underlying parsers.
* @throws FeedException if the feed could not be parsed
*
*/
public WireFeed build(org.w3c.dom.Document document) throws IllegalArgumentException,FeedException {
DOMBuilder domBuilder = new DOMBuilder();
try {
Document jdomDoc = domBuilder.build(document);
return build(jdomDoc);
}
catch (IllegalArgumentException ex) {
throw ex;
}
catch (Exception ex) {
throw new ParsingFeedException("Invalid XML",ex);
}
}
/**
* Builds an WireFeed (RSS or Atom) from an JDOM document.
* <p>
* NOTE: All other build methods delegate to this method.
* <p>
* @param document JDOM document to read to create the WireFeed.
* @return the WireFeed read from the JDOM document.
* @throws IllegalArgumentException thrown if feed type could not be understood by any of the underlying parsers.
* @throws FeedException if the feed could not be parsed
*
*/
public WireFeed build(Document document) throws IllegalArgumentException,FeedException {
WireFeedParser parser = getFeedParsers().getParserFor(document);
if (parser==null) {
throw new IllegalArgumentException("Invalid document");
}
return parser.parse(document, _validate);
}
/**
* Creates and sets up a org.jdom.input.SAXBuilder for parsing.
*
* @return a new org.jdom.input.SAXBuilder object
*/
protected SAXBuilder createSAXBuilder() {
SAXBuilder saxBuilder = new SAXBuilder(_validate);
saxBuilder.setEntityResolver(RESOLVER);
//
// This code is needed to fix the security problem outlined in http://www.securityfocus.com/archive/1/297714
//
// Unfortunately there isn't an easy way to check if an XML parser supports a particular feature, so
// we need to set it and catch the exception if it fails. We also need to subclass the JDom SAXBuilder
// class in order to get access to the underlying SAX parser - otherwise the features don't get set until
// we are already building the document, by which time it's too late to fix the problem.
//
// Crimson is one parser which is known not to support these features.
try {
XMLReader parser = saxBuilder.createParser();
try {
parser.setFeature("http://xml.org/sax/features/external-general-entities", false);
saxBuilder.setFeature("http://xml.org/sax/features/external-general-entities", false);
} catch (SAXNotRecognizedException e) {
// ignore
} catch (SAXNotSupportedException e) {
// ignore
}
try {
parser.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
saxBuilder.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
} catch (SAXNotRecognizedException e) {
// ignore
} catch (SAXNotSupportedException e) {
// ignore
}
try {
parser.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
saxBuilder.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
} catch (SAXNotRecognizedException e) {
// ignore
} catch (SAXNotSupportedException e) {
// ignore
}
} catch (JDOMException e) {
throw new IllegalStateException("JDOM could not create a SAX parser");
}
saxBuilder.setExpandEntities(false);
return saxBuilder;
}
}