GWC make use of XMLUtils to make better use of GeoTools Hints (#1534)

* Add PMD rules to check and recommend use of XMLUtils
* Using GT utility classes for XML parsing/producing
* GeoRSSReader: making use of XMLUtils utility class from GT
* Adding a PMD rule to avoid direct calls to XMLInputFactory.newInstance()
* Also go through XMLUtils for sensible defaults on DocumentBuilderFactory
* XMLConfiguration - block external schema resolution
* Make use of XMLUtils.newSchemaFactory() and fix up validation based on GeoWebCache 2.0.0

---------

Co-authored-by: Pierre Mauduit <pierre.mauduit@camptocamp.com>

Author: jodygarnett

geowebcache/core/pom.xml

@@ -23,6 +23,10 @@
       <groupId>org.geotools</groupId>
       <artifactId>gt-coverage</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.geotools</groupId>
+      <artifactId>gt-xml</artifactId>
+    </dependency>
     <dependency>
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-collections4</artifactId>

geowebcache/core/src/main/java/org/geowebcache/config/XMLConfiguration.java

@@ -21,7 +21,9 @@
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.OutputStream;
 import java.io.OutputStreamWriter;
+import java.io.PrintWriter;
 import java.io.UnsupportedEncodingException;
 import java.net.MalformedURLException;
 import java.net.URL;
@@ -41,19 +43,21 @@
 import java.util.logging.Logger;
 import java.util.stream.Collectors;
 import javax.annotation.Nullable;
+import javax.xml.XMLConstants;
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.transform.Transformer;
 import javax.xml.transform.TransformerException;
-import javax.xml.transform.TransformerFactory;
 import javax.xml.transform.TransformerFactoryConfigurationError;
 import javax.xml.transform.dom.DOMResult;
 import javax.xml.transform.dom.DOMSource;
+import javax.xml.transform.stream.StreamResult;
 import javax.xml.transform.stream.StreamSource;
 import javax.xml.validation.Schema;
 import javax.xml.validation.SchemaFactory;
 import javax.xml.validation.Validator;
 import org.geotools.util.logging.Logging;
+import org.geotools.xml.XMLUtils;
 import org.geowebcache.GeoWebCacheEnvironment;
 import org.geowebcache.GeoWebCacheException;
 import org.geowebcache.GeoWebCacheExtensions;
@@ -117,6 +121,10 @@ public class XMLConfiguration
 
     public static final String DEFAULT_CONFIGURATION_FILE_NAME = "geowebcache.xml";
 
+    public static final String SCHEMA_NAMESPACE_PREFIX = "http://geowebcache.org/schema/";
+
+    public static final String DEFAULT_SCHEMA_RESOURCE = "geowebcache.xsd";
+
     private static Logger log = Logging.getLogger(XMLConfiguration.class.getName());
 
     /** Web app context, used to look up {@link XMLConfigurationProvider}s. */
@@ -614,9 +622,9 @@ private synchronized void addOrReplaceGridSet(final XMLGridSet gridSet) throws I
     static Node loadDocument(InputStream xmlFile) throws ConfigurationException, IOException {
         Node topNode = null;
         try {
-            DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
+            DocumentBuilderFactory docBuilderFactory = XMLUtils.newDocumentBuilderFactory();
             docBuilderFactory.setNamespaceAware(true);
-            DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
+            DocumentBuilder docBuilder = XMLUtils.newDocumentBuilder(docBuilderFactory);
             topNode = checkAndTransform(docBuilder.parse(xmlFile));
         } catch (Exception e) {
             throw (IOException) new IOException(e.getMessage()).initCause(e);
@@ -629,14 +637,12 @@ private static Node checkAndTransform(Document doc) throws ConfigurationExceptio
         Node rootNode = doc.getDocumentElement();
 
         // debugPrint(rootNode);
-
         if (!rootNode.getNodeName().equals("gwcConfiguration")) {
             log.config("The configuration file is of the pre 1.0 type, trying to convert.");
             rootNode = applyTransform(rootNode, "geowebcache_pre10.xsl").getFirstChild();
         }
 
         // debugPrint(rootNode);
-
         if (rootNode.getNamespaceURI().equals("http://geowebcache.org/schema/1.0.0")) {
             log.config("Updating configuration from 1.0.0 to 1.0.1");
             rootNode = applyTransform(rootNode, "geowebcache_100.xsl").getFirstChild();
@@ -716,6 +722,11 @@ private static Node checkAndTransform(Document doc) throws ConfigurationExceptio
             rootNode = applyTransform(rootNode, "geowebcache_151.xsl").getFirstChild();
         }
 
+        if (!rootNode.getNamespaceURI().equals("http://geowebcache.org/schema/2.0.0")) {
+            log.config("Updating configuration to 2.0.0");
+            rootNode = applyTransform(rootNode, "geowebcache_200.xsl").getFirstChild();
+        }
+
         // Check again after transform
         if (!rootNode.getNodeName().equals("gwcConfiguration")) {
             log.log(Level.SEVERE, "Unable to parse file, expected gwcConfiguration at root after transform.");
@@ -726,8 +737,8 @@ private static Node checkAndTransform(Document doc) throws ConfigurationExceptio
                 validate(rootNode);
                 log.config("TileLayerConfiguration file validated fine.");
             } catch (SAXException e) {
-                log.warning("GWC configuration validation error: " + e.getMessage());
-                log.warning(
+                log.fine("GWC configuration validation error: " + e.getMessage());
+                log.fine(
                         "Will try to use configuration anyway. Please check the order of declared elements against the schema.");
             } catch (IOException e) {
                 throw new RuntimeException(e.getMessage(), e);
@@ -739,11 +750,14 @@ private static Node checkAndTransform(Document doc) throws ConfigurationExceptio
 
     static void validate(Node rootNode) throws SAXException, IOException {
         // Perform validation
-        // TODO dont know why this one suddenly failed to look up, revert to
-        // XMLConstants.W3C_XML_SCHEMA_NS_URI
-        SchemaFactory factory = SchemaFactory.newInstance("http://www.w3.org/2001/XMLSchema");
+        SchemaFactory factory = XMLUtils.newSchemaFactory(XMLConstants.W3C_XML_SCHEMA_NS_URI);
+        // We do not need access to external schemas
+        factory.setProperty(XMLConstants.ACCESS_EXTERNAL_SCHEMA, "");
+        factory.setProperty(XMLConstants.ACCESS_EXTERNAL_DTD, "");
         try (InputStream is = XMLConfiguration.class.getResourceAsStream("geowebcache.xsd")) {
-
+            if (is == null) {
+                throw new IOException("Could not load schema resource 'geowebcache.xsd'");
+            }
             Schema schema = factory.newSchema(new StreamSource(is));
             Validator validator = schema.newValidator();
 
@@ -758,7 +772,7 @@ static String getCurrentSchemaVersion() {
 
         Document dom;
         try (InputStream is = XMLConfiguration.class.getResourceAsStream("geowebcache.xsd")) {
-            dom = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(is);
+            dom = XMLUtils.newDocumentBuilder().parse(is);
         } catch (Exception e) {
             throw new RuntimeException(e);
         }
@@ -777,7 +791,7 @@ private static Node applyTransform(Node oldRootNode, String xslFilename) {
         try (InputStream is = XMLConfiguration.class.getResourceAsStream(xslFilename)) {
 
             try {
-                transformer = TransformerFactory.newInstance().newTransformer(new StreamSource(is));
+                transformer = XMLUtils.newTransformer(new StreamSource(is));
                 transformer.transform(new DOMSource(oldRootNode), result);
             } catch (TransformerFactoryConfigurationError | TransformerException e) {
                 log.log(Level.FINE, e.getMessage(), e);
@@ -1462,4 +1476,17 @@ public void deinitialize() throws Exception {
         this.layers = null;
         this.gwcConfig = null;
     }
+
+    /** Print a DOM tree to an output stream or if there is an exception while doing so, print the stack trace. */
+    public static void printDom(Node dom, OutputStream os) {
+        Transformer trans;
+        PrintWriter w = new PrintWriter(os);
+        try {
+            trans = XMLUtils.newTransformer(); // XMLUtils.newTransformer()
+            trans.transform(new DOMSource(dom), new StreamResult(new OutputStreamWriter(os)));
+        } catch (TransformerException e) {
+            w.println("An error ocurred while transforming the given DOM:");
+            e.printStackTrace(w);
+        }
+    }
 }

geowebcache/core/src/main/resources/org/geowebcache/config/geowebcache.xsd

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xml="http://www.w3.org/XML/1998/namespace"
-  targetNamespace="http://geowebcache.org/schema/1.28.0" xmlns:gwc="http://geowebcache.org/schema/1.28.0"
-  elementFormDefault="qualified" version="1.28.0">
+  targetNamespace="http://geowebcache.org/schema/2.0.0" xmlns:gwc="http://geowebcache.org/schema/2.0.0"
+  elementFormDefault="qualified" version="2.0.0">
 
   <xs:element name="gwcConfiguration">
     <xs:annotation>

geowebcache/core/src/main/resources/org/geowebcache/config/geowebcache_200.xsl

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="utf-8"?>
+<xsl:stylesheet xmlns:gwc="http://geowebcache.org/schema/1.6.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+<xsl:output method="xml" version="1.0" encoding="utf-8" indent="yes"/>
+
+<xsl:template match="node()|*">
+  <xsl:copy>
+    <xsl:apply-templates/>
+  </xsl:copy>
+</xsl:template>
+
+<xsl:template match="/|comment()|processing-instruction()">
+    <xsl:copy>
+      <xsl:apply-templates/>
+    </xsl:copy>
+</xsl:template>
+
+<xsl:template match="*">
+    <xsl:element name="{local-name()}">
+      <xsl:apply-templates select="@*|node()"/>
+    </xsl:element>
+</xsl:template>
+
+<xsl:template match="@*">
+    <xsl:attribute name="{local-name()}">
+      <xsl:value-of select="."/>
+    </xsl:attribute>
+</xsl:template>
+
+<xsl:template match="gwc:keyword">
+  <string><xsl:apply-templates/></string>
+</xsl:template>
+
+<xsl:template match="gwc:gwcConfiguration">
+  <gwcConfiguration xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="http://geowebcache.org/schema/2.0.0"
+    xsi:schemaLocation="http://geowebcache.org/schema/2.0.0 http://geowebcache.org/schema/2.0.0/geowebcache.xsd">
+    <xsl:apply-templates/>
+  </gwcConfiguration>
+</xsl:template>
+
+</xsl:stylesheet>

geowebcache/core/src/test/java/org/geowebcache/config/ServerConfigurationTest.java

@@ -36,7 +36,7 @@
 
 public class ServerConfigurationTest {
 
-    private static final String VERSION_PATTERN = "1(\\.\\d+)+(\\-\\w+)*";
+    private static final String VERSION_PATTERN = "2(\\.\\d+)+(\\-\\w+)*";
 
     ServerConfiguration config;
 

geowebcache/core/src/test/java/org/geowebcache/config/XMLConfigurationBackwardsCompatibilityTest.java

@@ -29,6 +29,7 @@
 import javax.xml.transform.TransformerFactory;
 import javax.xml.transform.dom.DOMSource;
 import javax.xml.transform.stream.StreamResult;
+import org.geotools.xml.XMLUtils;
 import org.geowebcache.GeoWebCacheException;
 import org.geowebcache.config.meta.ServiceInformation;
 import org.geowebcache.filter.request.RequestFilter;
@@ -45,7 +46,9 @@ public class XMLConfigurationBackwardsCompatibilityTest {
 
     public static final String GWC_125_CONFIG_FILE = "geowebcache_125.xml";
 
-    public static final String LATEST_FILENAME = "geowebcache_130.xml";
+    public static final String GWC_130_CONFIG_FILE = "geowebcache_130.xml";
+
+    public static final String LATEST_FILENAME = "geowebcache_200.xml";
 
     @Test
     public void testLoadPre10() throws Exception {
@@ -227,14 +230,14 @@ private XMLConfiguration loadConfig(String fileName) throws Exception {
 
     /** Utility method to print out a dom. */
     protected void print(Document dom) throws Exception {
-        TransformerFactory txFactory = TransformerFactory.newInstance();
+        TransformerFactory txFactory = XMLUtils.newTransformerFactory();
         try {
             txFactory.setAttribute("{http://xml.apache.org/xalan}indent-number", Integer.valueOf(2));
         } catch (Exception e) {
             // some
         }
 
-        Transformer tx = txFactory.newTransformer();
+        Transformer tx = XMLUtils.newTransformer(txFactory);
         tx.setOutputProperty(OutputKeys.METHOD, "xml");
         tx.setOutputProperty(OutputKeys.INDENT, "yes");