GUACAMOLE-566: Implement GuacamoleExceptionMapper to deal with

exceptions thrown in REST APIs in extensions.

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

@@ -39,6 +39,7 @@ 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.apache.guacamole.rest.GuacamoleExceptionMapper;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -418,6 +419,9 @@ public class ExtensionModule extends ServletModule {
         bind(LanguageResourceService.class).toInstance(languageResourceService);
         bind(PatchResourceService.class).toInstance(patchResourceService);
 
+        // Get ExceptionMapper to rewrite exceptions in JSON.
+        bind(GuacamoleExceptionMapper.class);
+        
         // Load initial language resources from servlet context
         languageResourceService.addLanguageResources(getServletContext());
 

guacamole/src/main/java/org/apache/guacamole/rest/GuacamoleExceptionMapper.java

@@ -0,0 +1,54 @@
+/*
+ * 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.rest;
+
+import com.google.inject.Singleton;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.ext.ExceptionMapper;
+import javax.ws.rs.ext.Provider;
+import org.apache.guacamole.GuacamoleException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A class that maps GuacamoleExceptions in a way that returns a
+ * custom response to the user via JSON rather than allowing the default
+ * web application error handling to take place.
+ */
+@Provider
+@Singleton
+public class GuacamoleExceptionMapper
+        implements ExceptionMapper<GuacamoleException> {
+        
+    private final Logger logger = LoggerFactory.getLogger(GuacamoleExceptionMapper.class);
+    
+    @Override
+    public Response toResponse(GuacamoleException e) {
+        logger.debug(">>>EXMAPPER<<< Mapping exception {}", e.getMessage());
+        return Response
+                .status(e.getHttpStatusCode())
+                .entity(new APIError(e))
+                .type(MediaType.APPLICATION_JSON)
+                .build();
+      
+    }
+    
+}

guacamole/src/main/java/org/apache/guacamole/rest/RESTExceptionWrapper.java

@@ -28,10 +28,7 @@ import javax.ws.rs.WebApplicationException;
 import javax.ws.rs.core.Response;
 import org.aopalliance.intercept.MethodInterceptor;
 import org.aopalliance.intercept.MethodInvocation;
-import org.apache.guacamole.GuacamoleClientException;
 import org.apache.guacamole.GuacamoleException;
-import org.apache.guacamole.GuacamoleResourceNotFoundException;
-import org.apache.guacamole.GuacamoleSecurityException;
 import org.apache.guacamole.GuacamoleUnauthorizedException;
 import org.apache.guacamole.rest.auth.AuthenticationService;
 import org.slf4j.Logger;

guacamole/src/main/java/org/apache/guacamole/rest/RESTServiceModule.java

@@ -88,6 +88,9 @@ public class RESTServiceModule extends ServletModule {
         MethodInterceptor interceptor = new RESTExceptionWrapper();
         requestInjection(interceptor);
         bindInterceptor(Matchers.any(), new RESTMethodMatcher(), interceptor);
+        
+        // Get the ExceptionMapper that will rewrite exceptions into JSON.
+        bind(GuacamoleExceptionMapper.class);
 
         // Set up the API endpoints
         bind(ExtensionRESTService.class);