/*
* Copyright (c) 2016 Network New Technologies Inc.
*
* Licensed 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 com.networknt.exception;
import com.networknt.config.Config;
import com.networknt.handler.MiddlewareHandler;
import com.networknt.status.Status;
import com.networknt.utility.ModuleRegistry;
import io.undertow.Handlers;
import io.undertow.server.HttpHandler;
import io.undertow.server.HttpServerExchange;
import io.undertow.server.protocol.framed.FrameHeaderData;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;
/**
* This is a middleware handler that should be put in the beginning of request/response
* chain. It wraps the entire chain so that any un-handled exceptions will finally reach
* here and to be handled gracefully. It is encouraged to handle exceptions in business
* handler because the context is clear and the exchange will be terminated at the right
* place.
*
* This handler is plugged in by default from light-codegen and it should be enabled on
* production as the last defence line. It also dispatch the request to worker thread
* pool from IO thread pool. Only turn this off if you understand the impact and have a
* very good reason to do so.
*
* @author Steve Hu
*/
public class ExceptionHandler implements MiddlewareHandler {
static final Logger logger = LoggerFactory.getLogger(ExceptionHandler.class);
public static final String CONFIG_NAME = "exception";
static final ExceptionConfig config =
(ExceptionConfig)Config.getInstance().getJsonObjectConfig(CONFIG_NAME, ExceptionConfig.class);
static final String STATUS_RUNTIME_EXCEPTION = "ERR10010";
static final String STATUS_UNCAUGHT_EXCEPTION = "ERR10011";
private volatile HttpHandler next;
public ExceptionHandler() {
}
@Override
public void handleRequest(final HttpServerExchange exchange) throws Exception {
// dispatch here to make sure that all exceptions will be capture in this handler
// otherwise, some of the exceptions will be captured in Connectors class in Undertow
// As we've updated Server.java to redirect the logs to slf4j but still it make sense
// to handle the exception on our ExcpetionHandler.
if (exchange.isInIoThread()) {
exchange.dispatch(this);
return;
}
try {
next.handleRequest(exchange);
} catch (Throwable e) {
logger.error("Exception:", e);
if(exchange.isResponseChannelAvailable()) {
//handle exceptions
if(e instanceof RuntimeException) {
// check if it is FrameworkException which is subclass of RuntimeException.
if(e instanceof FrameworkException) {
FrameworkException fe = (FrameworkException)e;
exchange.setStatusCode(fe.getStatus().getStatusCode());
exchange.getResponseSender().send(fe.getStatus().toString());
} else {
Status status = new Status(STATUS_RUNTIME_EXCEPTION);
exchange.setStatusCode(status.getStatusCode());
exchange.getResponseSender().send(status.toString());
}
} else {
if(e instanceof ApiException) {
ApiException ae = (ApiException)e;
exchange.setStatusCode(ae.getStatus().getStatusCode());
exchange.getResponseSender().send(ae.getStatus().toString());
} else {
Status status = new Status(STATUS_UNCAUGHT_EXCEPTION);
exchange.setStatusCode(status.getStatusCode());
exchange.getResponseSender().send(status.toString());
}
}
}
} finally {
// at last, clean the MDC. Most likely, correlationId in side.
//logger.debug("Clear MDC");
MDC.clear();
}
}
@Override
public HttpHandler getNext() {
return next;
}
@Override
public MiddlewareHandler setNext(final HttpHandler next) {
Handlers.handlerNotNull(next);
this.next = next;
return this;
}
@Override
public boolean isEnabled() {
return config.isEnabled();
}
@Override
public void register() {
ModuleRegistry.registerModule(ExceptionHandler.class.getName(), Config.getInstance().getJsonMapConfigNoCache(CONFIG_NAME), null);
}
}