content: /*
   * 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.spark.network.sasl;
  
  import java.io.IOException;
  import java.util.Map;
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.auth.callback.NameCallback;
  import javax.security.auth.callback.PasswordCallback;
  import javax.security.auth.callback.UnsupportedCallbackException;
  import javax.security.sasl.RealmCallback;
  import javax.security.sasl.RealmChoiceCallback;
  import javax.security.sasl.Sasl;
  import javax.security.sasl.SaslClient;
  import javax.security.sasl.SaslException;
  
  import com.google.common.base.Throwables;
  import com.google.common.collect.ImmutableMap;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static org.apache.spark.network.sasl.SparkSaslServer.*;
  
  /**
   * A SASL Client for Spark which simply keeps track of the state of a single SASL session, from the
   * initial state to the "authenticated" state. This client initializes the protocol via a
   * firstToken, which is then followed by a set of challenges and responses.
   */
  public class SparkSaslClient implements SaslEncryptionBackend {
    private static final Logger logger = LoggerFactory.getLogger(SparkSaslClient.class);
  
    private final String secretKeyId;
    private final SecretKeyHolder secretKeyHolder;
    private final String expectedQop;
    private SaslClient saslClient;
  
    public SparkSaslClient(String secretKeyId, SecretKeyHolder secretKeyHolder, boolean encrypt) {
      this.secretKeyId = secretKeyId;
      this.secretKeyHolder = secretKeyHolder;
      this.expectedQop = encrypt ? QOP_AUTH_CONF : QOP_AUTH;
  
      Map<String, String> saslProps = ImmutableMap.<String, String>builder()
        .put(Sasl.QOP, expectedQop)
        .build();
      try {
        this.saslClient = Sasl.createSaslClient(new String[] { DIGEST }, null, null, DEFAULT_REALM,
          saslProps, new ClientCallbackHandler());
      } catch (SaslException e) {
        throw Throwables.propagate(e);
      }
    }
  
    /** Used to initiate SASL handshake with server. */
    public synchronized byte[] firstToken() {
      if (saslClient != null && saslClient.hasInitialResponse()) {
        try {
          return saslClient.evaluateChallenge(new byte[0]);
        } catch (SaslException e) {
          throw Throwables.propagate(e);
        }
      } else {
        return new byte[0];
      }
    }
  
    /** Determines whether the authentication exchange has completed. */
    public synchronized boolean isComplete() {
      return saslClient != null && saslClient.isComplete();
    }
  
    /** Returns the value of a negotiated property. */
    public Object getNegotiatedProperty(String name) {
      return saslClient.getNegotiatedProperty(name);
    }
  
    /**
     * Respond to server's SASL token.
     * @param token contains server's SASL token
     * @return client's response SASL token
     */
    public synchronized byte[] response(byte[] token) {
      try {
        return saslClient != null ? saslClient.evaluateChallenge(token) : new byte[0];
      } catch (SaslException e) {
        throw Throwables.propagate(e);
      }
    }
  
    /**
     * Disposes of any system resources or security-sensitive information the
     * SaslClient might be using.
     */
    @Override
    public synchronized void dispose() {
      if (saslClient != null) {
        try {
          saslClient.dispose();
        } catch (SaslException e) {
          // ignore
        } finally {
          saslClient = null;
        }
      }
    }
  
    /**
     * Implementation of javax.security.auth.callback.CallbackHandler
     * that works with share secrets.
     */
    private class ClientCallbackHandler implements CallbackHandler {
      @Override
      public void handle(Callback[] callbacks) throws IOException, UnsupportedCallbackException {
  
        for (Callback callback : callbacks) {
          if (callback instanceof NameCallback) {
            logger.trace("SASL client callback: setting username");
            NameCallback nc = (NameCallback) callback;
            nc.setName(encodeIdentifier(secretKeyHolder.getSaslUser(secretKeyId)));
          } else if (callback instanceof PasswordCallback) {
            logger.trace("SASL client callback: setting password");
            PasswordCallback pc = (PasswordCallback) callback;
            pc.setPassword(encodePassword(secretKeyHolder.getSecretKey(secretKeyId)));
          } else if (callback instanceof RealmCallback) {
            logger.trace("SASL client callback: setting realm");
            RealmCallback rc = (RealmCallback) callback;
            rc.setText(rc.getDefaultText());
          } else if (callback instanceof RealmChoiceCallback) {
            // ignore (?)
          } else {
            throw new UnsupportedCallbackException(callback, "Unrecognized SASL DIGEST-MD5 Callback");
          }
        }
      }
    }
  
    @Override
    public byte[] wrap(byte[] data, int offset, int len) throws SaslException {
      return saslClient.wrap(data, offset, len);
    }
  
    @Override
    public byte[] unwrap(byte[] data, int offset, int len) throws SaslException {
      return saslClient.unwrap(data, offset, len);
    }
  
  }
  