GUACAMOLE-1364: Merge add support for overriding extension priority without renaming files.

extensions/guacamole-auth-cas/src/main/resources/guac-manifest.json

@@ -3,7 +3,7 @@
     "guacamoleVersion" : "1.3.0",
 
     "name"      : "CAS Authentication Extension",
-    "namespace" : "guac-cas",
+    "namespace" : "cas",
 
     "authProviders" : [
         "org.apache.guacamole.auth.cas.CASAuthenticationProvider"

extensions/guacamole-auth-header/src/main/resources/guac-manifest.json

@@ -3,7 +3,7 @@
     "guacamoleVersion" : "1.2.0",
 
     "name"      : "HTTP Header Authentication Extension",
-    "namespace" : "guac-header",
+    "namespace" : "header",
 
     "authProviders" : [
         "org.apache.guacamole.auth.header.HTTPHeaderAuthenticationProvider"

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/resources/guac-manifest.json

@@ -3,7 +3,7 @@
     "guacamoleVersion" : "1.3.0",
 
     "name"      : "MySQL Authentication",
-    "namespace" : "guac-mysql",
+    "namespace" : "mysql",
 
     "authProviders" : [
         "org.apache.guacamole.auth.mysql.MySQLAuthenticationProvider",

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-postgresql/src/main/resources/guac-manifest.json

@@ -3,7 +3,7 @@
     "guacamoleVersion" : "1.3.0",
 
     "name"      : "PostgreSQL Authentication",
-    "namespace" : "guac-postgresql",
+    "namespace" : "postgresql",
 
     "authProviders" : [
         "org.apache.guacamole.auth.postgresql.PostgreSQLAuthenticationProvider",

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-sqlserver/src/main/resources/guac-manifest.json

@@ -3,7 +3,7 @@
     "guacamoleVersion" : "1.3.0",
 
     "name"      : "SQLServer Authentication",
-    "namespace" : "guac-sqlserver",
+    "namespace" : "sqlserver",
 
     "authProviders" : [
         "org.apache.guacamole.auth.sqlserver.SQLServerAuthenticationProvider",

extensions/guacamole-auth-json/src/main/resources/guac-manifest.json

@@ -3,7 +3,7 @@
     "guacamoleVersion" : "1.3.0",
 
     "name"      : "Encrypted JSON Authentication",
-    "namespace" : "guac-json",
+    "namespace" : "json",
 
     "authProviders" : [
         "org.apache.guacamole.auth.json.JSONAuthenticationProvider"

extensions/guacamole-auth-ldap/src/main/resources/guac-manifest.json

@@ -3,7 +3,7 @@
     "guacamoleVersion" : "1.3.0",
 
     "name"      : "LDAP Authentication",
-    "namespace" : "guac-ldap",
+    "namespace" : "ldap",
 
     "authProviders" : [
         "org.apache.guacamole.auth.ldap.LDAPAuthenticationProvider"

extensions/guacamole-auth-openid/src/main/resources/guac-manifest.json

@@ -3,7 +3,7 @@
     "guacamoleVersion" : "1.3.0",
 
     "name"      : "OpenID Authentication Extension",
-    "namespace" : "guac-openid",
+    "namespace" : "openid",
 
     "authProviders" : [
         "org.apache.guacamole.auth.openid.OpenIDAuthenticationProvider"

guacamole/src/main/java/org/apache/guacamole/extension/Extension.java

@@ -26,7 +26,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipException;
@@ -55,6 +55,11 @@ public class Extension {
      */
     private static final String MANIFEST_NAME = "guac-manifest.json";
 
+    /**
+     * The extension .jar file.
+     */
+    private final File file;
+
     /**
      * The parsed manifest file of this extension, describing the location of
      * resources within the extension.
@@ -144,7 +149,7 @@ public class Extension {
             return Collections.<String, Resource>emptyMap();
 
         // Add classpath resource for each path provided
-        Map<String, Resource> resources = new HashMap<String, Resource>(paths.size());
+        Map<String, Resource> resources = new LinkedHashMap<>(paths.size());
         for (String path : paths)
             resources.put(path, new ClassPathResource(classLoader, mimetype, path));
 
@@ -173,7 +178,7 @@ public class Extension {
             return Collections.<String, Resource>emptyMap();
 
         // Add classpath resource for each path/mimetype pair provided
-        Map<String, Resource> resources = new HashMap<String, Resource>(resourceTypes.size());
+        Map<String, Resource> resources = new LinkedHashMap<>(resourceTypes.size());
         for (Map.Entry<String, String> resource : resourceTypes.entrySet()) {
 
             // Get path and mimetype from entry
@@ -357,6 +362,9 @@ public class Extension {
      */
     public Extension(final ClassLoader parent, final File file) throws GuacamoleException {
 
+        // Associate extension abstraction with original file
+        this.file = file;
+
         try {
 
             // Open extension
@@ -427,6 +435,16 @@ public class Extension {
             largeIcon = null;
     }
 
+    /**
+     * Returns the .jar file containing this Guacamole extension.
+     *
+     * @return
+     *     The extension .jar file.
+     */
+    public File getFile() {
+        return file;
+    }
+
     /**
      * Returns the version of the Guacamole web application for which this
      * extension was built.

guacamole/src/main/java/org/apache/guacamole/extension/ExtensionModule.java

@@ -27,6 +27,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -40,7 +41,6 @@ import org.apache.guacamole.properties.StringSetProperty;
 import org.apache.guacamole.resource.Resource;
 import org.apache.guacamole.resource.ResourceServlet;
 import org.apache.guacamole.resource.SequenceResource;
-import org.apache.guacamole.resource.WebApplicationResource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -105,6 +105,22 @@ public class ExtensionModule extends ServletModule {
 
     };
 
+    /**
+     * A comma-separated list of the namespaces of all extensions that should
+     * be loaded in a specific order. The special value "*" can be used in
+     * lieu of a namespace to represent all extensions that are not listed. All
+     * extensions explicitly listed will be sorted in the order given, while
+     * all extensions not explicitly listed will be sorted by their filenames.
+     */
+    public static final ExtensionOrderProperty EXTENSION_PRIORITY = new ExtensionOrderProperty() {
+
+        @Override
+        public String getName() {
+            return "extension-priority";
+        }
+
+    };
+
     /**
      * The Guacamole server environment.
      */
@@ -394,9 +410,101 @@ public class ExtensionModule extends ServletModule {
 
     }
 
+    /**
+     * Returns a comparator that sorts extensions by their desired load order,
+     * as dictated by the "extension-priority" property and their filenames.
+     *
+     * @return
+     *     A comparator that sorts extensions by their desired load order.
+     */
+    private Comparator<Extension> getExtensionLoadOrder() {
+
+        // Parse desired sort order of extensions
+        try {
+            return environment.getProperty(EXTENSION_PRIORITY, ExtensionOrderProperty.DEFAULT_COMPARATOR);
+        }
+
+        // Sort by filename if the desired order cannot be read
+        catch (GuacamoleException e) {
+            logger.warn("The list of extensions specified via the \"{}\" property could not be parsed: {}", EXTENSION_PRIORITY.getName(), e.getMessage());
+            logger.debug("Unable to parse \"{}\" property.", EXTENSION_PRIORITY.getName(), e);
+            return ExtensionOrderProperty.DEFAULT_COMPARATOR;
+        }
+
+    }
+
+    /**
+     * Returns a list of all installed extensions in the order they should be
+     * loaded. Extension load order is dictated by the "extension-priority"
+     * property and by extension filename. Each extension within
+     * GUACAMOLE_HOME/extensions is read and validated, but not fully loaded.
+     * It is the responsibility of the caller to continue the load process with
+     * the extensions in the returned list.
+     *
+     * @return
+     *     A list of all installed extensions, ordered by load priority.
+     */
+    private List<Extension> getExtensions() {
+
+        // Retrieve and validate extensions directory
+        File extensionsDir = new File(environment.getGuacamoleHome(), EXTENSIONS_DIRECTORY);
+        if (!extensionsDir.isDirectory())
+            return Collections.emptyList();
+
+        // Retrieve list of all extension files within extensions directory
+        File[] extensionFiles = extensionsDir.listFiles(new FileFilter() {
+
+            @Override
+            public boolean accept(File file) {
+                return file.isFile() && file.getName().endsWith(EXTENSION_SUFFIX);
+            }
+
+        });
+
+        // Verify contents are accessible
+        if (extensionFiles == null) {
+            logger.warn("Although GUACAMOLE_HOME/" + EXTENSIONS_DIRECTORY + " exists, its contents cannot be read.");
+            return Collections.emptyList();
+        }
+
+        // Read (but do not fully load) each extension within the extension
+        // directory
+        List<Extension> extensions = new ArrayList<>(extensionFiles.length);
+        for (File extensionFile : extensionFiles) {
+
+            logger.debug("Reading extension: \"{}\"", extensionFile.getName());
+
+            try {
+
+                // Load extension from file
+                Extension extension = new Extension(getParentClassLoader(), extensionFile);
+
+                // Validate Guacamole version of extension
+                if (!isCompatible(extension.getGuacamoleVersion())) {
+                    logger.debug("Declared Guacamole version \"{}\" of extension \"{}\" is not compatible with this version of Guacamole.",
+                            extension.getGuacamoleVersion(), extensionFile.getName());
+                    throw new GuacamoleServerException("Extension \"" + extension.getName() + "\" is not "
+                            + "compatible with this version of Guacamole.");
+                }
+
+                extensions.add(extension);
+
+            }
+            catch (GuacamoleException e) {
+                logger.error("Extension \"{}\" could not be loaded: {}", extensionFile.getName(), e.getMessage());
+                logger.debug("Unable to load extension.", e);
+            }
+
+        }
+
+        extensions.sort(getExtensionLoadOrder());
+        return extensions;
+
+    }
+
     /**
      * Loads all extensions within the GUACAMOLE_HOME/extensions directory, if
-     * any, adding their static resource to the given resoure collections.
+     * any, adding their static resource to the given resource collections.
      *
      * @param javaScriptResources
      *     A modifiable collection of static JavaScript resources which may
@@ -420,47 +528,26 @@ public class ExtensionModule extends ServletModule {
             Collection<Resource> cssResources,
             Set<String> toleratedAuthProviders) {
 
-        // Retrieve and validate extensions directory
-        File extensionsDir = new File(environment.getGuacamoleHome(), EXTENSIONS_DIRECTORY);
-        if (!extensionsDir.isDirectory())
-            return;
+        // Advise of current extension load order and how the order may be
+        // changed
+        List<Extension> extensions = getExtensions();
+        if (extensions.size() > 1) {
+            logger.info("Multiple extensions are installed and will be "
+                    + "loaded in order of decreasing priority:");
 
-        // Retrieve list of all extension files within extensions directory
-        File[] extensionFiles = extensionsDir.listFiles(new FileFilter() {
-
-            @Override
-            public boolean accept(File file) {
-                return file.isFile() && file.getName().endsWith(EXTENSION_SUFFIX);
+            for (Extension extension : extensions) {
+                logger.info(" - [{}] \"{}\" ({})", extension.getNamespace(),
+                        extension.getName(), extension.getFile());
             }
 
-        });
-
-        // Verify contents are accessible
-        if (extensionFiles == null) {
-            logger.warn("Although GUACAMOLE_HOME/" + EXTENSIONS_DIRECTORY + " exists, its contents cannot be read.");
-            return;
+            logger.info("To change this order, set the \"{}\" property or "
+                    + "rename the extension files. The default priority of "
+                    + "extensions is dictated by the sort order of their "
+                    + "filenames.", EXTENSION_PRIORITY.getName());
         }
 
-        // Sort files lexicographically
-        Arrays.sort(extensionFiles);
-
-        // Load each extension within the extension directory
-        for (File extensionFile : extensionFiles) {
-
-            logger.debug("Loading extension: \"{}\"", extensionFile.getName());
-
-            try {
-
-                // Load extension from file
-                Extension extension = new Extension(getParentClassLoader(), extensionFile);
-
-                // Validate Guacamole version of extension
-                if (!isCompatible(extension.getGuacamoleVersion())) {
-                    logger.debug("Declared Guacamole version \"{}\" of extension \"{}\" is not compatible with this version of Guacamole.",
-                            extension.getGuacamoleVersion(), extensionFile.getName());
-                    throw new GuacamoleServerException("Extension \"" + extension.getName() + "\" is not "
-                            + "compatible with this version of Guacamole.");
-                }
+        // Load all extensions
+        for (Extension extension : extensions) {
 
             // Add any JavaScript / CSS resources
             javaScriptResources.addAll(extension.getJavaScriptResources().values());
@@ -491,13 +578,7 @@ public class ExtensionModule extends ServletModule {
                 serve("/images/logo-144.png").with(new ResourceServlet(extension.getLargeIcon()));
 
             // Log successful loading of extension by name
-                logger.info("Extension \"{}\" loaded.", extension.getName());
-
-            }
-            catch (GuacamoleException e) {
-                logger.error("Extension \"{}\" could not be loaded: {}", extensionFile.getName(), e.getMessage());
-                logger.debug("Unable to load extension.", e);
-            }
+            logger.info("Extension \"{}\" ({}) loaded.", extension.getName(), extension.getNamespace());
 
         }
 

guacamole/src/main/java/org/apache/guacamole/extension/ExtensionOrderProperty.java

@@ -0,0 +1,163 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.guacamole.extension;
+
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.regex.Pattern;
+import org.apache.guacamole.GuacamoleException;
+import org.apache.guacamole.properties.GuacamoleProperty;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A GuacamoleProperty that defines the order of Guacamole extensions. The
+ * property value is a comma-separated list of extension namespaces, with "*"
+ * used to represent all extensions that aren't listed. For example, a value
+ * like "saml, *, ldap" would order SAML support first and LDAP support last,
+ * with all other extensions loaded between the two in filename order. For
+ * values without "*", all other extensions are implicitly after all extensions
+ * that are explicitly listed.
+ */
+public abstract class ExtensionOrderProperty implements GuacamoleProperty<Comparator<Extension>> {
+
+    /**
+     * Logger for this class.
+     */
+    private static final Logger logger = LoggerFactory.getLogger(ExtensionOrderProperty.class);
+
+    /**
+     * A pattern which matches against the delimiters between values. This is
+     * currently simply a comma and any following whitespace. Parts of the
+     * input string which match this pattern will not be included in the parsed
+     * result.
+     */
+    private static final Pattern DELIMITER_PATTERN = Pattern.compile(",\\s*");
+
+    /**
+     * Static comparator instance that sorts extensions by their filenames
+     * alone.
+     */
+    public static final Comparator<Extension> DEFAULT_COMPARATOR = new ExtensionComparator();
+
+    /**
+     * Comparator that sorts extensions in order of priority, as dictated by a
+     * list of the extensions that should be ordered first or last. All
+     * extensions not explicitly listed will instead be sorted by filename.
+     */
+    private static class ExtensionComparator implements Comparator<Extension> {
+
+        /**
+         * The string value representing the set of all extensions not
+         * explicitly listed.
+         */
+        private final String OTHER_EXTENSIONS = "*";
+
+        /**
+         * The relative priorities of all extensions. Any extension not listed
+         * within this map should be sorted with the priority value stored in
+         * {@link #defaultPriority}.
+         */
+        private final Map<String, Integer> extensionPriority;
+
+        /**
+         * The relative priority that should be used for all extensions not
+         * explicitly listed within {@link #extensionPriority}.
+         */
+        private final int defaultPriority;
+
+        /**
+         * Creates a new ExtensionComparator that sorts all extensions by their
+         * filenames only.
+         */
+        public ExtensionComparator() {
+            defaultPriority = 0;
+            extensionPriority = Collections.emptyMap();
+        }
+
+        /**
+         * Creates a new ExtensionComparator that ensures each of the given
+         * extensions are sorted in the relative order listed, with any
+         * extensions not explicitly listed sorted by filename.
+         *
+         * @param name
+         *     The name of the property defining the provided list of
+         *     extensions.
+         *
+         * @param extensions
+         *     The namespaces of the extensions in the order they should be
+         *     sorted, with the special value "*" functioning as a
+         *     placeholder for all extensions that are not explicitly listed.
+         */
+        public ExtensionComparator(String name, String... extensions) {
+
+            extensionPriority = new HashMap<>(extensions.length);
+
+            for (int priority = 0; priority < extensions.length; priority++) {
+                String extension = extensions[priority];
+                if (extensionPriority.putIfAbsent(extension, priority) != null)
+                    logger.warn("The value \"{}\" was specified multiple "
+                            + "times for property \"{}\". Only the first "
+                            + "occurrence of this value will have any effect.",
+                            extension, name);
+            }
+
+            Integer otherExtensionPriority = extensionPriority.remove(OTHER_EXTENSIONS);
+            if (otherExtensionPriority != null)
+                defaultPriority = otherExtensionPriority;
+            else
+                defaultPriority = extensions.length;
+
+        }
+
+        @Override
+        public int compare(Extension extA, Extension extB) {
+
+            int priorityA = extensionPriority.getOrDefault(extA.getNamespace(), defaultPriority);
+            int priorityB = extensionPriority.getOrDefault(extB.getNamespace(), defaultPriority);
+
+            // Sort by explicit priority first
+            if (priorityA != priorityB)
+                return priorityA - priorityB;
+
+            // Sort all extensions without explicit priorities by their
+            // filenames (no extensions will have the same priority except
+            // those that aren't explicitly listed)
+            return extA.getFile().compareTo(extB.getFile());
+
+        }
+
+    }
+
+    @Override
+    public Comparator<Extension> parseValue(String value) throws GuacamoleException {
+
+        // If no property provided, return null.
+        if (value == null)
+            return null;
+
+        // Split string into a set of individual values
+        return new ExtensionComparator(getName(), DELIMITER_PATTERN.split(value));
+
+    }
+
+}