001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    package org.apache.hadoop.hdfs.web;
019    
020    import java.io.IOException;
021    
022    import org.apache.hadoop.security.UserGroupInformation;
023    import org.apache.hadoop.security.authentication.client.Authenticator;
024    import org.apache.hadoop.security.authentication.client.KerberosAuthenticator;
025    import org.apache.hadoop.security.authentication.client.PseudoAuthenticator;
026    
027    /**
028     * Use UserGroupInformation as a fallback authenticator
029     * if the server does not use Kerberos SPNEGO HTTP authentication.
030     */
031    public class KerberosUgiAuthenticator extends KerberosAuthenticator {
032      @Override
033      protected Authenticator getFallBackAuthenticator() {
034        return new PseudoAuthenticator() {
035          @Override
036          protected String getUserName() {
037            try {
038              return UserGroupInformation.getLoginUser().getUserName();
039            } catch (IOException e) {
040              throw new SecurityException("Failed to obtain current username", e);
041            }
042          }
043        };
044      }
045    }