/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hive.thrift.client;

import java.io.IOException;
import java.security.PrivilegedExceptionAction;

import org.apache.hadoop.hive.thrift.TFilterTransport;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.thrift.transport.TTransport;
import org.apache.thrift.transport.TTransportException;

/**
  * The Thrift SASL transports call Sasl.createSaslServer and Sasl.createSaslClient
  * inside open(). So, we need to assume the correct UGI when the transport is opened
  * so that the SASL mechanisms have access to the right principal. This transport
  * wraps the Sasl transports to set up the right UGI context for open().
  *
  * This is used on the client side, where the API explicitly opens a transport to
  * the server.
  */
 public class TUGIAssumingTransport extends TFilterTransport {
   protected UserGroupInformation ugi;

   public TUGIAssumingTransport(TTransport wrapped, UserGroupInformation ugi) {
     super(wrapped);
     this.ugi = ugi;
   }

   @Override
   public void open() throws TTransportException {
     try {
       ugi.doAs(new PrivilegedExceptionAction<Void>() {
         public Void run() {
           try {
             wrapped.open();
           } catch (TTransportException tte) {
             // Wrap the transport exception in an RTE, since UGI.doAs() then goes
             // and unwraps this for us out of the doAs block. We then unwrap one
             // more time in our catch clause to get back the TTE. (ugh)
             throw new RuntimeException(tte);
           }
           return null;
         }
       });
     } catch (IOException ioe) {
       throw new RuntimeException("Received an ioe we never threw!", ioe);
     } catch (InterruptedException ie) {
       throw new RuntimeException("Received an ie we never threw!", ie);
     } catch (RuntimeException rte) {
       if (rte.getCause() instanceof TTransportException) {
         throw (TTransportException)rte.getCause();
       } else {
         throw rte;
       }
     }
   }
 }
