| /** |
| * 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.hadoop.lib.servlet; |
| |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| |
| import javax.servlet.Filter; |
| import javax.servlet.FilterChain; |
| import javax.servlet.FilterConfig; |
| import javax.servlet.ServletException; |
| import javax.servlet.ServletRequest; |
| import javax.servlet.ServletResponse; |
| import java.io.IOException; |
| import java.net.InetAddress; |
| import java.net.UnknownHostException; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Filter that resolves the requester hostname. |
| */ |
| @InterfaceAudience.Private |
| public class HostnameFilter implements Filter { |
| static final ThreadLocal<String> HOSTNAME_TL = new ThreadLocal<String>(); |
| private static final Logger log = LoggerFactory.getLogger(HostnameFilter.class); |
| |
| /** |
| * Initializes the filter. |
| * <p> |
| * This implementation is a NOP. |
| * |
| * @param config filter configuration. |
| * |
| * @throws ServletException thrown if the filter could not be initialized. |
| */ |
| @Override |
| public void init(FilterConfig config) throws ServletException { |
| } |
| |
| /** |
| * Resolves the requester hostname and delegates the request to the chain. |
| * <p> |
| * The requester hostname is available via the {@link #get} method. |
| * |
| * @param request servlet request. |
| * @param response servlet response. |
| * @param chain filter chain. |
| * |
| * @throws IOException thrown if an IO error occurs. |
| * @throws ServletException thrown if a servlet error occurs. |
| */ |
| @Override |
| public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) |
| throws IOException, ServletException { |
| try { |
| String hostname; |
| try { |
| String address = request.getRemoteAddr(); |
| if (address != null) { |
| hostname = InetAddress.getByName(address).getCanonicalHostName(); |
| } else { |
| log.warn("Request remote address is NULL"); |
| hostname = "???"; |
| } |
| } catch (UnknownHostException ex) { |
| log.warn("Request remote address could not be resolved, {0}", ex.toString(), ex); |
| hostname = "???"; |
| } |
| HOSTNAME_TL.set(hostname); |
| chain.doFilter(request, response); |
| } finally { |
| HOSTNAME_TL.remove(); |
| } |
| } |
| |
| /** |
| * Returns the requester hostname. |
| * |
| * @return the requester hostname. |
| */ |
| public static String get() { |
| return HOSTNAME_TL.get(); |
| } |
| |
| /** |
| * Destroys the filter. |
| * <p> |
| * This implementation is a NOP. |
| */ |
| @Override |
| public void destroy() { |
| } |
| } |