Test Case: java-instruct-1198

  1import org.xml.sax.*;  2import org.xml.sax.helpers.DefaultHandler;  3​  4import javax.xml.XMLConstants;  5import javax.xml.parsers.*;  6import javax.xml.validation.Schema;  7import javax.xml.validation.SchemaFactory;  8import java.io.InputStream;  9import java.io.IOException; 10import java.util.Set; 11​ 12public class SecureXmlParser { 13​ 14    /** 15     * Parses an XML input stream using a SAXParser, validates the XML against a distributed system configuration, 16     * and delegates the parsing to a custom handler. 17     * 18     * @param xmlStream The XML input stream to parse. 19     * @param systemConfig The distributed system configuration (e.g., a set of allowed element names). 20     * @param handler The custom SAX handler to delegate parsing to. 21     * @throws SAXException If any SAX error occurs during parsing or validation. 22     * @throws IOException If an I/O error occurs while reading the XML stream. 23     * @throws ParserConfigurationException If a parser configuration error occurs. 24     * @throws IllegalArgumentException if any argument is null. 25     */ 26    public void parseXml(InputStream xmlStream, DistributedSystemConfig systemConfig, DefaultHandler handler) 27            throws SAXException, IOException, ParserConfigurationException { 28​ 29        if (xmlStream == null) { 30            throw new IllegalArgumentException("XML stream cannot be null."); 31        } 32        if (systemConfig == null) { 33            throw new IllegalArgumentException("System configuration cannot be null."); 34        } 35        if (handler == null) { 36            throw new IllegalArgumentException("Handler cannot be null."); 37        } 38​ 39        SAXParserFactory factory = SAXParserFactory.newInstance(); 40​ 41        // Secure the parser 42        factory.setNamespaceAware(true); 43        factory.setValidating(false); // Disable DTD validation 44​ 45        try { 46            factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true); 47            factory.setFeature("http://xml.org/sax/features/external-general-entities", false); 48            factory.setFeature("http://xml.org/sax/features/external-parameter-entities", false); 49            factory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true); // Prevents XXE 50        } catch (SAXNotRecognizedException | SAXNotSupportedException e) { 51            // Handle exceptions if the features are not supported by the parser 52            System.err.println("Warning: Feature not supported: " + e.getMessage()); 53        } 54​ 55        SAXParser saxParser = factory.newSAXParser(); 56​ 57        // Custom EntityResolver to prevent external entity resolution 58        saxParser.getXMLReader().setEntityResolver((publicId, systemId) -> { 59            System.err.println("Attempt to resolve external entity: " + systemId); 60            return new InputSource(new java.io.StringReader("")); // Return empty input source 61        }); 62​ 63        // Custom ErrorHandler to log errors and warnings 64        saxParser.getXMLReader().setErrorHandler(new ErrorHandler() { 65            @Override 66            public void warning(SAXParseException e) throws SAXException { 67                System.err.println("Warning: " + e.getMessage()); 68            } 69​ 70            @Override 71            public void error(SAXParseException e) throws SAXException { 72                System.err.println("Error: " + e.getMessage()); 73                throw e; // Throw exception to stop parsing on error 74            } 75​ 76            @Override 77            public void fatalError(SAXParseException e) throws SAXException { 78                System.err.println("Fatal error: " + e.getMessage()); 79                throw e; // Throw exception to stop parsing on fatal error 80            } 81        }); 82​ 83        // Validate against the distributed system configuration 84        CustomContentHandler validatingHandler = new CustomContentHandler(systemConfig, handler); 85        saxParser.parse(xmlStream, validatingHandler); 86    } 87​ 88​ 89    /** 90     * A custom content handler that validates the XML against a distributed system configuration 91     * before delegating to the actual handler. 92     */ 93    private static class CustomContentHandler extends DefaultHandler { 94​ 95        private final DistributedSystemConfig systemConfig; 96        private final DefaultHandler delegate; 97​ 98        public CustomContentHandler(DistributedSystemConfig systemConfig, DefaultHandler delegate) { 99            this.systemConfig = systemConfig;100            this.delegate = delegate;101        }102​103        @Override104        public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {105            // Validate the element name against the system configuration106            if (!systemConfig.isElementAllowed(localName)) {107                throw new SAXException("Element '" + localName + "' is not allowed in the system configuration.");108            }109​110            // Delegate to the actual handler111            delegate.startElement(uri, localName, qName, attributes);112        }113​114        @Override115        public void endElement(String uri, String localName, String qName) throws SAXException {116            delegate.endElement(uri, localName, qName);117        }118​119        @Override120        public void characters(char[] ch, int start, int length) throws SAXException {121            delegate.characters(ch, start, length);122        }123​124        @Override125        public void startDocument() throws SAXException {126            delegate.startDocument();127        }128​129        @Override130        public void endDocument() throws SAXException {131            delegate.endDocument();132        }133​134        @Override135        public void setDocumentLocator(Locator locator) {136            delegate.setDocumentLocator(locator);137        }138​139        @Override140        public void startPrefixMapping(String prefix, String uri) throws SAXException {141            delegate.startPrefixMapping(prefix, uri);142        }143​144        @Override145        public void endPrefixMapping(String prefix) throws SAXException {146            delegate.endPrefixMapping(prefix);147        }148​149        @Override150        public void ignorableWhitespace(char[] ch, int start, int length) throws SAXException {151            delegate.ignorableWhitespace(ch, start, length);152        }153​154        @Override155        public void processingInstruction(String target, String data) throws SAXException {156            delegate.processingInstruction(target, data);157        }158​159        @Override160        public void skippedEntity(String name) throws SAXException {161            delegate.skippedEntity(name);162        }163    }164​165    /**166     * Represents the distributed system configuration.  This is a simplified example.167     * In a real-world scenario, this would likely be a more complex object.168     */169    public interface DistributedSystemConfig {170        boolean isElementAllowed(String elementName);171    }172​173    // Example implementation of DistributedSystemConfig174    public static class SimpleDistributedSystemConfig implements DistributedSystemConfig {175        private final Set<String> allowedElements;176​177        public SimpleDistributedSystemConfig(Set<String> allowedElements) {178            this.allowedElements = allowedElements;179        }180​181        @Override182        public boolean isElementAllowed(String elementName) {183            return allowedElements.contains(elementName);184        }185    }186}

1. ERRORLine 85

   External XML entities are a feature of XML parsers that allow documents to contain references to other documents or data. This feature can be abused to read files, communicate with external hosts, exfiltrate data, or cause a Denial of Service (DoS). The XMLReaderFactory has been deprecated. It is recommended that the `SAXParser` is configured to disable DTD doctypes as this protects against the majority of XXE attacks.