com.rometools.rome.io.WireFeedInput Maven / Gradle / Ivy
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/*
* 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.rometools.rome.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.Locale;
import java.util.Map;
import java.util.WeakHashMap;
import org.jdom2.Document;
import org.jdom2.JDOMException;
import org.jdom2.input.DOMBuilder;
import org.jdom2.input.JDOMParseException;
import org.jdom2.input.sax.XMLReaders;
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.rometools.rome.feed.WireFeed;
import com.rometools.rome.feed.impl.ConfigurableClassLoader;
import com.rometools.rome.io.impl.FeedParsers;
import com.rometools.rome.io.impl.XmlFixerReader;
/**
* Parses an XML document (File, InputStream, Reader, W3C SAX InputSource, W3C DOM Document or JDom
* DOcument) into an WireFeed (RSS/Atom).
*
* 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).
*
* The WireFeedInput useds liberal parsers.
*/
public class WireFeedInput {
private static final InputSource EMPTY_INPUTSOURCE = new InputSource(new ByteArrayInputStream(new byte[0]));
private static final EntityResolver RESOLVER = new EmptyEntityResolver();
private static Map clMap = new WeakHashMap();
private final boolean validate;
private final Locale locale;
private boolean xmlHealerOn;
private boolean allowDoctypes = false;
private static FeedParsers getFeedParsers() {
synchronized (WireFeedInput.class) {
final ClassLoader classLoader = ConfigurableClassLoader.INSTANCE.getClassLoader();
FeedParsers parsers = clMap.get(classLoader);
if (parsers == null) {
parsers = new FeedParsers();
clMap.put(classLoader, parsers);
}
return parsers;
}
}
private static class EmptyEntityResolver implements EntityResolver {
@Override
public InputSource resolveEntity(final String publicId, final String systemId) {
if (systemId != null && systemId.endsWith(".dtd")) {
return EMPTY_INPUTSOURCE;
}
return null;
}
}
/**
* Returns the list of supported input feed types.
*
*
* @see WireFeed for details on the format of these strings.
*
* @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.
*
*
*/
public WireFeedInput() {
this(false, Locale.US);
}
/**
* Creates a WireFeedInput instance.
*
*
* @param validate indicates if the input should be validated. NOT IMPLEMENTED YET (validation
* does not happen)
*
*/
public WireFeedInput(final boolean validate, final Locale locale) {
this.validate = false; // TODO FIX THIS THINGY
xmlHealerOn = true;
this.locale = locale;
}
/**
* Enables XML healing in the WiredFeedInput instance.
*
* Healing trims leading chars from the stream (empty spaces and comments) until the XML prolog.
*
* Healing resolves HTML entities (from literal to code number) in the reader.
*
* The healing is done only with the build(File) and build(Reader) signatures.
*
* By default is TRUE.
*
*
* @param heals TRUE enables stream healing, FALSE disables it.
*
*/
public void setXmlHealerOn(final boolean heals) {
xmlHealerOn = heals;
}
/**
* Indicates if the WiredFeedInput instance will XML heal (if necessary) the character stream.
*
* Healing trims leading chars from the stream (empty spaces and comments) until the XML prolog.
*
* Healing resolves HTML entities (from literal to code number) in the reader.
*
* The healing is done only with the build(File) and build(Reader) signatures.
*
* By default is TRUE.
*
*
* @return TRUE if healing is enabled, FALSE if not.
*
*/
public boolean getXmlHealerOn() {
return xmlHealerOn;
}
/**
* Indicates whether Doctype declarations are allowed.
*
* @return true when Doctype declarations are allowed, false otherwise
*/
public boolean isAllowDoctypes() {
return allowDoctypes;
}
/**
* Since ROME 1.5.1 we fixed a security vulnerability by disallowing Doctype declarations by default.
* This change breaks the compatibility with at least RSS 0.91N because it requires a Doctype declaration.
* You are able to allow Doctype declarations again with this property. You should only activate it
* when the feeds that you process are absolutely trustful.
*
* @param allowDoctypes true when Doctype declarations should be allowed again, false otherwise
*/
public void setAllowDoctypes(boolean allowDoctypes) {
this.allowDoctypes = allowDoctypes;
}
/**
* Builds an WireFeed (RSS or Atom) from a file.
*
* NOTE: This method delages to the 'AsbtractFeed WireFeedInput#build(org.jdom2.Document)'.
*
*
* @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(final File file) throws FileNotFoundException, IOException, IllegalArgumentException, FeedException {
WireFeed feed;
Reader reader = new FileReader(file);
try {
if (xmlHealerOn) {
reader = new XmlFixerReader(reader);
}
feed = this.build(reader);
} finally {
reader.close();
}
return feed;
}
/**
* Builds an WireFeed (RSS or Atom) from an Reader.
*
* NOTE: This method delages to the 'AsbtractFeed WireFeedInput#build(org.jdom2.Document)'.
*
*
* @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 {
final SAXBuilder saxBuilder = createSAXBuilder();
try {
if (xmlHealerOn) {
reader = new XmlFixerReader(reader);
}
final Document document = saxBuilder.build(reader);
return this.build(document);
} catch (final JDOMParseException ex) {
throw new ParsingFeedException("Invalid XML: " + ex.getMessage(), ex);
} catch (final IllegalArgumentException ex) {
throw ex;
} catch (final Exception ex) {
throw new ParsingFeedException("Invalid XML", ex);
}
}
/**
* Builds an WireFeed (RSS or Atom) from an W3C SAX InputSource.
*
* NOTE: This method delages to the 'AsbtractFeed WireFeedInput#build(org.jdom2.Document)'.
*
*
* @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(final InputSource is) throws IllegalArgumentException, FeedException {
final SAXBuilder saxBuilder = createSAXBuilder();
try {
final Document document = saxBuilder.build(is);
return this.build(document);
} catch (final JDOMParseException ex) {
throw new ParsingFeedException("Invalid XML: " + ex.getMessage(), ex);
} catch (final IllegalArgumentException ex) {
throw ex;
} catch (final Exception ex) {
throw new ParsingFeedException("Invalid XML", ex);
}
}
/**
* Builds an WireFeed (RSS or Atom) from an W3C DOM document.
*
* NOTE: This method delages to the 'AsbtractFeed WireFeedInput#build(org.jdom2.Document)'.
*
*
* @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(final org.w3c.dom.Document document) throws IllegalArgumentException, FeedException {
final DOMBuilder domBuilder = new DOMBuilder();
try {
final Document jdomDoc = domBuilder.build(document);
return this.build(jdomDoc);
} catch (final IllegalArgumentException ex) {
throw ex;
} catch (final Exception ex) {
throw new ParsingFeedException("Invalid XML", ex);
}
}
/**
* Builds an WireFeed (RSS or Atom) from an JDOM document.
*
* NOTE: All other build methods delegate to this method.
*
*
* @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(final Document document) throws IllegalArgumentException, FeedException {
final WireFeedParser parser = getFeedParsers().getParserFor(document);
if (parser == null) {
throw new IllegalArgumentException("Invalid document");
}
return parser.parse(document, validate, locale);
}
/**
* Creates and sets up a org.jdom2.input.SAXBuilder for parsing.
*
* @return a new org.jdom2.input.SAXBuilder object
*/
protected SAXBuilder createSAXBuilder() {
SAXBuilder saxBuilder;
if (validate) {
saxBuilder = new SAXBuilder(XMLReaders.DTDVALIDATING);
} else {
saxBuilder = new SAXBuilder(XMLReaders.NONVALIDATING);
}
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 {
final XMLReader parser = saxBuilder.createParser();
setFeature(saxBuilder, parser, "http://xml.org/sax/features/external-general-entities", false);
setFeature(saxBuilder, parser, "http://xml.org/sax/features/external-parameter-entities", false);
setFeature(saxBuilder, parser, "http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
if(!allowDoctypes) {
setFeature(saxBuilder, parser, "http://apache.org/xml/features/disallow-doctype-decl", true);
}
} catch (final JDOMException e) {
throw new IllegalStateException("JDOM could not create a SAX parser", e);
}
saxBuilder.setExpandEntities(false);
return saxBuilder;
}
private void setFeature(SAXBuilder saxBuilder, XMLReader parser, String feature, boolean value) {
if (isFeatureSupported(parser, feature, value)) {
saxBuilder.setFeature(feature, value);
}
}
private boolean isFeatureSupported(XMLReader parser, String feature, boolean value) {
try {
parser.setFeature(feature, value);
return true;
} catch (final SAXNotRecognizedException e) {
return false;
} catch (final SAXNotSupportedException e) {
return false;
}
}
}