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.celeborn.common.network.sasl;
  
  import static org.apache.celeborn.common.network.sasl.SaslUtils.*;
  
  import java.util.Map;
  
  import javax.annotation.Nullable;
  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.AuthorizeCallback;
  import javax.security.sasl.RealmCallback;
  import javax.security.sasl.Sasl;
  import javax.security.sasl.SaslException;
  import javax.security.sasl.SaslServer;
  
  import com.google.common.base.Preconditions;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.celeborn.common.network.client.TransportClient;
  
  /**
   * A SASL Server for Celeborn which simply keeps track of the state of a single SASL session, from
   * the initial state to the "authenticated" state. (It is not a server in the sense of accepting
   * connections on some socket.)
   */
  public class CelebornSaslServer {
    private static final Logger logger = LoggerFactory.getLogger(CelebornSaslServer.class);
  
    private SaslServer saslServer;
  
    public CelebornSaslServer(
        String saslMechanism,
        @Nullable Map<String, String> saslProps,
        @Nullable CallbackHandler callbackHandler) {
      Preconditions.checkNotNull(saslMechanism);
      initializeSaslProviders();
      try {
        this.saslServer =
            Sasl.createSaslServer(saslMechanism, null, DEFAULT_REALM, saslProps, callbackHandler);
      } catch (SaslException e) {
        throw new IllegalArgumentException(e);
      }
    }
  
    /** Determines whether the authentication exchange has completed successfully. */
    public synchronized boolean isComplete() {
      return saslServer != null && saslServer.isComplete();
    }
  
    /** Returns the value of a negotiated property. */
    public synchronized Object getNegotiatedProperty(String name) {
      return saslServer.getNegotiatedProperty(name);
    }
  
    /**
     * Used to respond to server SASL tokens.
     *
     * @param token Server's SASL token
     * @return response to send back to the server.
     */
    public synchronized byte[] response(byte[] token) {
      try {
        return saslServer != null ? saslServer.evaluateResponse(token) : EMPTY_BYTE_ARRAY;
      } catch (SaslException e) {
        throw new RuntimeException(e);
      }
    }
  
    /**
     * Disposes of any system resources or security-sensitive information the SaslServer might be
     * using.
     */
    public synchronized void dispose() {
      if (saslServer != null) {
        try {
          saslServer.dispose();
        } catch (SaslException e) {
          // ignore
        } finally {
          saslServer = null;
        }
      }
    }
  
    /**
     * Implementation of javax.security.auth.callback.CallbackHandler for SASL DIGEST-MD5 mechanism.
     */
    static class DigestCallbackHandler implements CallbackHandler {
      private final SecretRegistry secretRegistry;
      private final TransportClient client;
  
      /**
       * The use of 'volatile' is not necessary here because the 'handle' invocation includes both the
       * NameCallback and PasswordCallback (with the name preceding the password), all within the same
       * thread.
       */
      private String userName = null;
  
      DigestCallbackHandler(TransportClient client, SecretRegistry secretRegistry) {
        this.client = Preconditions.checkNotNull(client);
        this.secretRegistry = Preconditions.checkNotNull(secretRegistry);
      }
  
      @Override
      public void handle(Callback[] callbacks) throws UnsupportedCallbackException, SaslException {
        for (Callback callback : callbacks) {
          if (callback instanceof NameCallback) {
            logger.trace("SASL server callback: setting username");
            NameCallback nc = (NameCallback) callback;
            String encodedName = nc.getName() != null ? nc.getName() : nc.getDefaultName();
            if (encodedName == null) {
              throw new SaslException("No username provided by client");
            }
            userName = decodeIdentifier(encodedName);
            client.setClientId(userName);
          } else if (callback instanceof PasswordCallback) {
            logger.trace("SASL server callback: setting password");
            PasswordCallback pc = (PasswordCallback) callback;
            String secret = secretRegistry.getSecretKey(userName);
            if (secret == null) {
              throw new RuntimeException("Registration information not found for " + userName);
            }
            pc.setPassword(encodePassword(secret));
          } else if (callback instanceof RealmCallback) {
            logger.trace("SASL server callback: setting realm");
            RealmCallback rc = (RealmCallback) callback;
            rc.setText(rc.getDefaultText());
          } else if (callback instanceof AuthorizeCallback) {
            AuthorizeCallback ac = (AuthorizeCallback) callback;
            String authId = ac.getAuthenticationID();
            String authzId = ac.getAuthorizationID();
            ac.setAuthorized(authId.equals(authzId));
            if (ac.isAuthorized()) {
              ac.setAuthorizedID(authzId);
            }
            logger.debug("SASL Authorization complete, authorized set to {}", ac.isAuthorized());
          } else {
            throw new UnsupportedCallbackException(callback, "Unrecognized callback: " + callback);
          }
        }
      }
    }
  }
  