Documents with an Internal Subset DOCTYPE shouldn't stop trying to bind

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/extensions/contentmodel/participants/diagnostics/LSPXMLParserConfiguration.java

@@ -0,0 +1,75 @@
+/*******************************************************************************
+* Copyright (c) 2019 Red Hat Inc. and others.
+* All rights reserved. This program and the accompanying materials
+* which accompanies this distribution, and is available at
+* http://www.eclipse.org/legal/epl-v20.html
+*
+* Contributors:
+*     Red Hat Inc. - initial API and implementation
+*******************************************************************************/
+package org.eclipse.lsp4xml.extensions.contentmodel.participants.diagnostics;
+
+import org.apache.xerces.impl.dtd.XMLDTDValidator;
+import org.apache.xerces.parsers.XIncludeAwareParserConfiguration;
+import org.apache.xerces.xni.XNIException;
+import org.apache.xerces.xni.parser.XMLComponentManager;
+import org.apache.xerces.xni.parser.XMLConfigurationException;
+
+/**
+ * Custom Xerces XML parser configuration to :
+ * 
+ * <ul>
+ * <li>disable only DTD validation if required</li>
+ * </ul>
+ *
+ */
+class LSPXMLParserConfiguration extends XIncludeAwareParserConfiguration {
+
+	private final boolean disableDTDValidation;
+
+	public LSPXMLParserConfiguration(boolean disableDTDValidation) {
+		this.disableDTDValidation = disableDTDValidation;
+	}
+
+	@Override
+	protected void reset() throws XNIException {
+		super.reset();
+		if (disableDTDValidation) {
+			// reset again DTD validator by setting "http://xml.org/sax/features/validation"
+			// to false.
+			disableDTDValidation();
+		}
+	}
+
+	private void disableDTDValidation() {
+		XMLDTDValidator validator = (XMLDTDValidator) super.getProperty(DTD_VALIDATOR);
+		if (validator != null) {
+			// Calling XMLDTDValidator#setFeature("http://xml.org/sax/features/validation",
+			// false) does nothing.
+			// The only way to set "http://xml.org/sax/features/validation" to false is to
+			// call XMLDTDValidator#reset with the proper component.
+			// We need to create a new component and not use the current configuration
+			// otherwise set
+			// "http://xml.org/sax/features/validation" to the configuration
+			// will update the other component and will disable validation too for XML
+			// Schema
+			XMLComponentManager disableDTDComponent = new XMLComponentManager() {
+
+				@Override
+				public Object getProperty(String propertyId) throws XMLConfigurationException {
+					return LSPXMLParserConfiguration.this.getProperty(propertyId);
+				}
+
+				@Override
+				public boolean getFeature(String featureId) throws XMLConfigurationException {
+					if ("http://xml.org/sax/features/validation".equals(featureId)) {
+						return false;
+					}
+					return LSPXMLParserConfiguration.this.getFeature(featureId);
+				}
+			};
+			validator.reset(disableDTDComponent);
+		}
+	}
+
+}

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/extensions/contentmodel/participants/diagnostics/XMLValidator.java

@@ -22,7 +22,6 @@
 
 import org.apache.xerces.impl.XMLEntityManager;
 import org.apache.xerces.parsers.SAXParser;
-import org.apache.xerces.parsers.XIncludeAwareParserConfiguration;
 import org.apache.xerces.xni.XNIException;
 import org.apache.xerces.xni.parser.XMLEntityResolver;
 import org.apache.xerces.xni.parser.XMLInputSource;
@@ -61,21 +60,20 @@ public class XMLValidator {
 	public static void doDiagnostics(DOMDocument document, XMLEntityResolver entityResolver,
 			List<Diagnostic> diagnostics, ContentModelSettings contentModelSettings, CancelChecker monitor) {
 		try {
-			// it should be better to cache XML Schema with XMLGrammarCachingConfiguration,
+			// It should be better to cache XML Schema with XMLGrammarCachingConfiguration,
 			// but we cannot use
 			// XMLGrammarCachingConfiguration because cache is done with target namespaces.
 			// There are conflicts when
 			// 2 XML Schemas don't define target namespaces.
-			XMLParserConfiguration configuration = new XIncludeAwareParserConfiguration(); // new
-																							// XMLGrammarCachingConfiguration();
+			LSPXMLParserConfiguration configuration = new LSPXMLParserConfiguration(
+					isDisableOnlyDTDValidation(document));
 
 			if (entityResolver != null) {
 				configuration.setProperty("http://apache.org/xml/properties/internal/entity-resolver", entityResolver); //$NON-NLS-1$
 			}
 
 			final LSPErrorReporterForXML reporter = new LSPErrorReporterForXML(document, diagnostics);
 			boolean externalDTDValid = checkExternalDTD(document, reporter, configuration);
-
 			SAXParser parser = new SAXParser(configuration);
 			// Add LSP error reporter to fill LSP diagnostics from Xerces errors
 			parser.setProperty("http://apache.org/xml/properties/internal/error-reporter", reporter);
@@ -124,6 +122,31 @@ public static void doDiagnostics(DOMDocument document, XMLEntityResolver entityR
 		}
 	}
 
+	/**
+	 * Returns true is DTD validation must be disabled and false otherwise.
+	 * 
+	 * @param document the DOM document
+	 * @return true is DTD validation must be disabled and false otherwise.
+	 */
+	private static boolean isDisableOnlyDTDValidation(DOMDocument document) {
+		// When XML declares a DOCTYPE only to define entities like
+		// <!DOCTYPE root [
+		// <!ENTITY foo "Bar">
+		// ]>
+		// Xerces try to validate the XML and report an error on each XML elements
+		// because they are not declared in the DOCTYPE.
+		// In this case, DTD validation must be disabled.
+		if (!document.hasDTD()) {
+			return false;
+		}
+		DOMDocumentType docType = document.getDoctype();
+		if (docType.getKindNode() != null) {
+			return false;
+		}
+		// Disable the DTD validation only if there are not <!ELEMENT or an <!ATTRLIST
+		return !docType.getChildren().stream().anyMatch(node -> node.isDTDElementDecl() || node.isDTDAttListDecl());
+	}
+
 	/**
 	 * Returns true if the given document has a valid DTD (or doesn't define a DTD)
 	 * and false otherwise.
@@ -143,7 +166,7 @@ private static boolean checkExternalDTD(DOMDocument document, LSPErrorReporterFo
 		if (docType.getKindNode() == null) {
 			return true;
 		}
-		
+
 		// When XML is bound with a DTD path which doesn't exist, Xerces throws an
 		// IOException which breaks the validation of XML syntax instead of reporting it
 		// (like XML Schema). Here we parse only the
@@ -159,7 +182,7 @@ private static boolean checkExternalDTD(DOMDocument document, LSPErrorReporterFo
 		String xml = document.getText().substring(0, end);
 		xml += "<root/>";
 		try {
-			
+
 			// Customize the entity manager to collect the error when DTD doesn't exist.
 			XMLEntityManager entityManager = new XMLEntityManager() {
 				@Override
@@ -185,7 +208,7 @@ public String setupCurrentEntity(String name, XMLInputSource xmlInputSource, boo
 				}
 			};
 			entityManager.reset(configuration);
-			
+
 			SAXParser parser = new SAXParser(configuration);
 			parser.setProperty("http://apache.org/xml/properties/internal/entity-manager", entityManager);
 			InputSource inputSource = new InputSource();

org.eclipse.lsp4xml/src/test/java/org/eclipse/lsp4xml/extensions/contentmodel/DTDDoctypeDiagnosticsTest.java

@@ -54,4 +54,40 @@ public void MSG_OPEN_PAREN_OR_ELEMENT_TYPE_REQUIRED_IN_CHILDREN() throws Excepti
 				d(2, 19, 20, DTDErrorCode.MSG_OPEN_PAREN_OR_ELEMENT_TYPE_REQUIRED_IN_CHILDREN));
 	}
 
+	@Test
+	public void disableDTDValidationWhenNoElementDecl() throws Exception {
+		String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n" + //
+				"<!DOCTYPE article [\r\n" + //
+				"  <!ENTITY nbsp \"entity-value\">\r\n" + //
+				"]>           \r\n" + //
+				"<article>\r\n" + //
+				"	&nbsp;\r\n" + //
+				"</article>";
+		// No error, here DOCTYPE declares only ENTITY -> DTD validation is disabled
+		XMLAssert.testDiagnosticsFor(xml);
+
+		xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n" + //
+				"<!DOCTYPE article [\r\n" + //
+				"  <!ENTITY nbsp \"entity-value\">\r\n" + //
+				"  <!ELEMENT element-name (#PCDATA)>\r\n" + //
+				"]>           \r\n" + //
+				"<article>\r\n" + //
+				"	&nbsp;\r\n" + //
+				"</article>";
+		// Error -> DTD validation defines a !ELEMENT entity-value which doesn't match
+		// the article root element
+		XMLAssert.testDiagnosticsFor(xml, d(5, 1, 8, DTDErrorCode.MSG_ELEMENT_NOT_DECLARED));
+
+		xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n" + //
+				"<!DOCTYPE article [\r\n" + //
+				"  <!ENTITY nbsp \"entity-value\">\r\n" + //
+				"  <!ELEMENT article (#PCDATA)>\r\n" + //
+				"]>           \r\n" + //
+				"<article>\r\n" + //
+				"	&nbsp;\r\n" + //
+				"</article>";
+		// No error, DTD validation is done and XML matches the article element
+		// declaration
+		XMLAssert.testDiagnosticsFor(xml);
+	}
 }