GUACAMOLE-641: Allow extensions to receive Environment via constructors.

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

@@ -23,6 +23,7 @@ import java.util.Set;
 import java.util.UUID;
 import org.apache.guacamole.GuacamoleClientException;
 import org.apache.guacamole.GuacamoleException;
+import org.apache.guacamole.environment.Environment;
 import org.apache.guacamole.net.auth.AuthenticatedUser;
 import org.apache.guacamole.net.auth.AuthenticationProvider;
 import org.apache.guacamole.net.auth.Credentials;
@@ -71,6 +72,9 @@ public class AuthenticationProviderFacade implements AuthenticationProvider {
      * facade will still succeed, but its use will result in errors being
      * logged, and all authentication attempts will fail.
      *
+     * @param environment
+     *      The Guacamole server environment.
+     *
      * @param authProviderClass
      *     The AuthenticationProvider subclass to instantiate.
      *
@@ -83,12 +87,12 @@ public class AuthenticationProviderFacade implements AuthenticationProvider {
      *     attempt. By default, errors during authentication halt the
      *     authentication process entirely.
      */
-    public AuthenticationProviderFacade(
+    public AuthenticationProviderFacade(Environment environment,
             Class<? extends AuthenticationProvider> authProviderClass,
             Set<String> tolerateFailures) {
         this.tolerateFailures = tolerateFailures;
-        this.authProvider = ProviderFactory.newInstance("authentication provider",
-            authProviderClass);
+        this.authProvider = ProviderFactory.newInstance(environment,
+                "authentication provider", authProviderClass);
     }
 
     @Override

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

@@ -199,7 +199,7 @@ public class ExtensionModule extends ServletModule {
         logger.debug("[{}] Binding AuthenticationProvider \"{}\".",
                 boundAuthenticationProviders.size(), authenticationProvider.getName());
         boundAuthenticationProviders.add(new AuthenticationProviderFacade(
-                authenticationProvider, tolerateFailures));
+                environment, authenticationProvider, tolerateFailures));
 
     }
 
@@ -255,7 +255,7 @@ public class ExtensionModule extends ServletModule {
 
         logger.debug("[{}] Binding listener \"{}\".",
                 boundListeners.size(), providerClass.getName());
-        boundListeners.addAll(ListenerFactory.createListeners(providerClass));
+        boundListeners.addAll(ListenerFactory.createListeners(environment, providerClass));
 
     }
 

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

@@ -30,6 +30,7 @@ import org.apache.guacamole.net.event.listener.*;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import org.apache.guacamole.environment.Environment;
 
 /**
  * A factory that reflectively instantiates Listener objects for a given
@@ -44,15 +45,20 @@ class ListenerFactory {
      * only listener type that will be returned. Otherwise, a list of Listener
      * objects that adapt the legacy listener interfaces will be returned.
      *
+     * @param environment
+     *      The Environment instance that should be passed to the constructor
+     *      of the given class, if a constructor accepting an Environment
+     *      instance is defined.
+     *
      * @param providerClass
      *      A class that represents a listener.
      *
      * @return
      *      The list of listeners represented by the given provider class.
      */
-    static List<Listener> createListeners(Class<?> providerClass) {
+    static List<Listener> createListeners(Environment environment, Class<?> providerClass) {
 
-        Object provider = ProviderFactory.newInstance("listener", providerClass);
+        Object provider = ProviderFactory.newInstance(environment, "listener", providerClass);
 
         if (provider instanceof Listener) {
             return Collections.singletonList((Listener) provider);

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

@@ -24,6 +24,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.lang.reflect.InvocationTargetException;
+import org.apache.guacamole.environment.Environment;
 
 /**
  * A utility for creating provider instances and logging unexpected outcomes
@@ -37,10 +38,18 @@ class ProviderFactory {
     private static final Logger logger = LoggerFactory.getLogger(ProviderFactory.class);
 
     /**
-     * Creates an instance of the specified provider class using the no-arg constructor.
+     * Creates an instance of the specified provider class using either the
+     * constructor accepting an instance of the Environment interface or, if no
+     * such constructor is defined, the no-arg constructor.
+     *
+     * @param environment
+     *      The Environment instance that should be passed to the constructor
+     *      of the given class, if a constructor accepting an Environment
+     *      instance is defined.
      *
      * @param typeName
-     *      The provider type name used for log messages; e.g. "authentication provider".
+     *      The provider type name used for log messages; e.g. "authentication
+     *      provider".
      *
      * @param providerClass
      *      The provider class to instantiate.
@@ -51,19 +60,33 @@ class ProviderFactory {
      * @return
      *      A provider instance or null if no instance was created due to error.
      */
-    static <T> T newInstance(String typeName, Class<? extends T> providerClass) {
+    static <T> T newInstance(Environment environment, String typeName,
+            Class<? extends T> providerClass) {
         T instance = null;
 
         try {
-            // Attempt to instantiate the provider
-            instance = providerClass.getConstructor().newInstance();
+
+            // Attempt to instantiate the provider while providing the
+            // Guacamole server's environment
+            try {
+                instance = providerClass.getConstructor(Environment.class).newInstance(environment);
+            }
+
+            // Fall back to no-arg constructor if no constructor accepts
+            // Environment
+            catch (NoSuchMethodException e) {
+                logger.debug("{} does not provide a constructor accepting "
+                        + "Environment. Falling back to no-arg constructor.",
+                        providerClass.getName());
+                instance = providerClass.getConstructor().newInstance();
+            }
+
         }
         catch (NoSuchMethodException e) {
             logger.error("The {} extension in use is not properly defined. "
                     + "Please contact the developers of the extension or, if you "
                     + "are the developer, turn on debug-level logging.", typeName);
-            logger.debug("{} is missing a default constructor.",
-                    providerClass.getName(), e);
+            logger.debug("{} is missing a usable constructor.", providerClass.getName(), e);
         }
         catch (SecurityException e) {
             logger.error("The Java security manager is preventing extensions "