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.security.Credentials;
033import org.apache.hadoop.security.UserGroupInformation;
034
035/**
036 * Serve delegation tokens over http for use in hftp.
037 */
038@SuppressWarnings("serial")
039public 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}