001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements. See the NOTICE file distributed with this
004     * work for additional information regarding copyright ownership. The ASF
005     * licenses this file to you under the Apache License, Version 2.0 (the
006     * "License"); you may not use this file except in compliance with the License.
007     * You may obtain a copy of the License at
008     * 
009     * http://www.apache.org/licenses/LICENSE-2.0
010     * 
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
013     * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
014     * License for the specific language governing permissions and limitations under
015     * the License.
016     */
017    package org.apache.hadoop.hdfs.server.namenode;
018    
019    import java.io.IOException;
020    import java.security.PrivilegedExceptionAction;
021    
022    import javax.servlet.ServletContext;
023    import javax.servlet.ServletException;
024    import javax.servlet.http.HttpServletRequest;
025    import javax.servlet.http.HttpServletResponse;
026    
027    import org.apache.commons.logging.Log;
028    import org.apache.commons.logging.LogFactory;
029    import org.apache.hadoop.conf.Configuration;
030    import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
031    import org.apache.hadoop.security.UserGroupInformation;
032    import org.apache.hadoop.security.token.Token;
033    
034    /**
035     * Cancel delegation tokens over http for use in hftp.
036     */
037    @SuppressWarnings("serial")
038    public class CancelDelegationTokenServlet extends DfsServlet {
039      private static final Log LOG = LogFactory.getLog(CancelDelegationTokenServlet.class);
040      public static final String PATH_SPEC = "/cancelDelegationToken";
041      public static final String TOKEN = "token";
042      
043      @Override
044      protected void doGet(final HttpServletRequest req, final HttpServletResponse resp)
045          throws ServletException, IOException {
046        final UserGroupInformation ugi;
047        final ServletContext context = getServletContext();
048        final Configuration conf = NameNodeHttpServer.getConfFromContext(context);
049        try {
050          ugi = getUGI(req, conf);
051        } catch(IOException ioe) {
052          LOG.info("Request for token received with no authentication from "
053              + req.getRemoteAddr(), ioe);
054          resp.sendError(HttpServletResponse.SC_FORBIDDEN, 
055              "Unable to identify or authenticate user");
056          return;
057        }
058        final NameNode nn = NameNodeHttpServer.getNameNodeFromContext(
059            context);
060        String tokenString = req.getParameter(TOKEN);
061        if (tokenString == null) {
062          resp.sendError(HttpServletResponse.SC_MULTIPLE_CHOICES,
063                         "Token to renew not specified");
064        }
065        final Token<DelegationTokenIdentifier> token = 
066          new Token<DelegationTokenIdentifier>();
067        token.decodeFromUrlString(tokenString);
068        
069        try {
070          ugi.doAs(new PrivilegedExceptionAction<Void>() {
071            @Override
072            public Void run() throws Exception {
073              nn.getRpcServer().cancelDelegationToken(token);
074              return null;
075            }
076          });
077        } catch(Exception e) {
078          LOG.info("Exception while cancelling token. Re-throwing. ", e);
079          resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
080                         e.getMessage());
081        }
082      }
083    }