001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *      http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019
020package org.apache.oozie.servlet;
021
022import org.apache.oozie.util.XLog;
023
024import javax.servlet.Filter;
025import javax.servlet.FilterChain;
026import javax.servlet.FilterConfig;
027import javax.servlet.ServletException;
028import javax.servlet.ServletRequest;
029import javax.servlet.ServletResponse;
030import java.io.IOException;
031import java.net.InetAddress;
032import java.net.UnknownHostException;
033
034/**
035 * Filter that resolves the requester hostname.
036 */
037public class HostnameFilter implements Filter {
038    private static final XLog LOG = XLog.getLog(HostnameFilter.class);
039
040    static final ThreadLocal<String> HOSTNAME_TL = new ThreadLocal<String>();
041
042    /**
043     * Initializes the filter.
044     * <p>
045     * This implementation is a NOP.
046     *
047     * @param config filter configuration.
048     *
049     * @throws ServletException thrown if the filter could not be initialized.
050     */
051    @Override
052    public void init(FilterConfig config) throws ServletException {
053    }
054
055    /**
056     * Resolves the requester hostname and delegates the request to the chain.
057     * <p>
058     * The requester hostname is available via the {@link #get} method.
059     *
060     * @param request servlet request.
061     * @param response servlet response.
062     * @param chain filter chain.
063     *
064     * @throws IOException thrown if an IO error occurrs.
065     * @throws ServletException thrown if a servet error occurrs.
066     */
067    @Override
068    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
069        throws IOException, ServletException {
070        try {
071            String hostname;
072            try {
073                String address = request.getRemoteAddr();
074                if (address != null) {
075                    hostname = InetAddress.getByName(address).getCanonicalHostName();
076                } else {
077                    LOG.warn("Request remote address is NULL");
078                    hostname = "???";
079                }
080            } catch (UnknownHostException ex) {
081                LOG.warn("Request remote address could not be resolved, {0}", ex.toString(), ex);
082                hostname = "???";
083            }
084            HOSTNAME_TL.set(hostname);
085            XLog.Info.get().clear();
086            chain.doFilter(request, response);
087        }
088        finally {
089            HOSTNAME_TL.remove();
090        }
091    }
092
093    /**
094     * Returns the requester hostname.
095     *
096     * @return the requester hostname.
097     */
098    public static String get() {
099        return HOSTNAME_TL.get();
100    }
101
102    /**
103     * Destroys the filter.
104     * <p>
105     * This implementation is a NOP.
106     */
107    @Override
108    public void destroy() {
109    }
110}