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.DataOutputStream;
020    import java.io.IOException;
021    import java.security.PrivilegedExceptionAction;
022    
023    import javax.servlet.ServletContext;
024    import javax.servlet.ServletException;
025    import javax.servlet.http.HttpServletRequest;
026    import javax.servlet.http.HttpServletResponse;
027    
028    import org.apache.commons.logging.Log;
029    import org.apache.commons.logging.LogFactory;
030    import org.apache.hadoop.conf.Configuration;
031    import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSecretManager;
032    import org.apache.hadoop.security.Credentials;
033    import org.apache.hadoop.security.UserGroupInformation;
034    
035    /**
036     * Serve delegation tokens over http for use in hftp.
037     */
038    @SuppressWarnings("serial")
039    public class GetDelegationTokenServlet extends DfsServlet {
040      private static final Log LOG = LogFactory.getLog(GetDelegationTokenServlet.class);
041      public static final String PATH_SPEC = "/getDelegationToken";
042      public static final String RENEWER = "renewer";
043      
044      @Override
045      protected void doGet(final HttpServletRequest req, final HttpServletResponse resp)
046          throws ServletException, IOException {
047        final UserGroupInformation ugi;
048        final ServletContext context = getServletContext();
049        final Configuration conf = NameNodeHttpServer.getConfFromContext(context);
050        try {
051          ugi = getUGI(req, conf);
052        } catch(IOException ioe) {
053          LOG.info("Request for token received with no authentication from "
054              + req.getRemoteAddr(), ioe);
055          resp.sendError(HttpServletResponse.SC_FORBIDDEN, 
056              "Unable to identify or authenticate user");
057          return;
058        }
059        LOG.info("Sending token: {" + ugi.getUserName() + "," + req.getRemoteAddr() +"}");
060        final NameNode nn = NameNodeHttpServer.getNameNodeFromContext(context);
061        String renewer = req.getParameter(RENEWER);
062        final String renewerFinal = (renewer == null) ? 
063            req.getUserPrincipal().getName() : renewer;
064        
065        DataOutputStream dos = null;
066        try {
067          dos = new DataOutputStream(resp.getOutputStream());
068          final DataOutputStream dosFinal = dos; // for doAs block
069          ugi.doAs(new PrivilegedExceptionAction<Void>() {
070            @Override
071            public Void run() throws IOException {
072              final Credentials ts = DelegationTokenSecretManager.createCredentials(
073                  nn, ugi, renewerFinal);
074              ts.write(dosFinal);
075              return null;
076            }
077          });
078    
079        } catch(Exception e) {
080          LOG.info("Exception while sending token. Re-throwing ", e);
081          resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
082        } finally {
083          if(dos != null) dos.close();
084        }
085      }
086    }