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 */
017package org.apache.hadoop.hdfs.server.namenode;
018
019import java.io.DataOutputStream;
020import java.io.IOException;
021import java.security.PrivilegedExceptionAction;
022
023import javax.servlet.ServletContext;
024import javax.servlet.ServletException;
025import javax.servlet.http.HttpServletRequest;
026import javax.servlet.http.HttpServletResponse;
027
028import org.apache.commons.logging.Log;
029import org.apache.commons.logging.LogFactory;
030import org.apache.hadoop.conf.Configuration;
031import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSecretManager;
032import org.apache.hadoop.hdfs.security.token.delegation.DelegationUtilsClient;
033import org.apache.hadoop.security.Credentials;
034import org.apache.hadoop.security.UserGroupInformation;
035
036/**
037 * Serve delegation tokens over http for use in hftp.
038 */
039@SuppressWarnings("serial")
040public class GetDelegationTokenServlet extends DfsServlet {
041  private static final Log LOG = LogFactory.getLog(GetDelegationTokenServlet.class);
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    LOG.info("Sending token: {" + ugi.getUserName() + "," + req.getRemoteAddr() +"}");
059    final NameNode nn = NameNodeHttpServer.getNameNodeFromContext(context);
060    String renewer = req.getParameter(DelegationUtilsClient.RENEWER);
061    final String renewerFinal = (renewer == null) ? 
062        req.getUserPrincipal().getName() : renewer;
063    
064    DataOutputStream dos = null;
065    try {
066      dos = new DataOutputStream(resp.getOutputStream());
067      final DataOutputStream dosFinal = dos; // for doAs block
068      ugi.doAs(new PrivilegedExceptionAction<Void>() {
069        @Override
070        public Void run() throws IOException {
071          final Credentials ts = DelegationTokenSecretManager.createCredentials(
072              nn, ugi, renewerFinal);
073          ts.write(dosFinal);
074          return null;
075        }
076      });
077
078    } catch(Exception e) {
079      LOG.info("Exception while sending token. Re-throwing ", e);
080      resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
081    } finally {
082      if(dos != null) dos.close();
083    }
084  }
085}