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    package org.apache.oozie.servlet;
020    
021    import org.apache.oozie.util.XLog;
022    
023    import javax.servlet.Filter;
024    import javax.servlet.FilterChain;
025    import javax.servlet.FilterConfig;
026    import javax.servlet.ServletException;
027    import javax.servlet.ServletRequest;
028    import javax.servlet.ServletResponse;
029    import java.io.IOException;
030    import java.net.InetAddress;
031    import java.net.UnknownHostException;
032    
033    /**
034     * Filter that resolves the requester hostname.
035     */
036    public class HostnameFilter implements Filter {
037        private static final XLog LOG = XLog.getLog(HostnameFilter.class);
038    
039        static final ThreadLocal<String> HOSTNAME_TL = new ThreadLocal<String>();
040    
041        /**
042         * Initializes the filter.
043         * <p/>
044         * This implementation is a NOP.
045         *
046         * @param config filter configuration.
047         *
048         * @throws ServletException thrown if the filter could not be initialized.
049         */
050        @Override
051        public void init(FilterConfig config) throws ServletException {
052        }
053    
054        /**
055         * Resolves the requester hostname and delegates the request to the chain.
056         * <p/>
057         * The requester hostname is available via the {@link #get} method.
058         *
059         * @param request servlet request.
060         * @param response servlet response.
061         * @param chain filter chain.
062         *
063         * @throws IOException thrown if an IO error occurrs.
064         * @throws ServletException thrown if a servet error occurrs.
065         */
066        @Override
067        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
068            throws IOException, ServletException {
069            try {
070                String hostname;
071                try {
072                    String address = request.getRemoteAddr();
073                    if (address != null) {
074                        hostname = InetAddress.getByName(address).getCanonicalHostName();
075                    } else {
076                        LOG.warn("Request remote address is NULL");
077                        hostname = "???";
078                    }
079                } catch (UnknownHostException ex) {
080                    LOG.warn("Request remote address could not be resolved, {0}", ex.toString(), ex);
081                    hostname = "???";
082                }
083                HOSTNAME_TL.set(hostname);
084                chain.doFilter(request, response);
085            }
086            finally {
087                HOSTNAME_TL.remove();
088            }
089        }
090    
091        /**
092         * Returns the requester hostname.
093         *
094         * @return the requester hostname.
095         */
096        public static String get() {
097            return HOSTNAME_TL.get();
098        }
099    
100        /**
101         * Destroys the filter.
102         * <p/>
103         * This implementation is a NOP.
104         */
105        @Override
106        public void destroy() {
107        }
108    }