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 com.datastax.oss.driver.api.core.auth;
  
  import com.datastax.oss.driver.internal.core.util.concurrent.CompletableFutures;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import edu.umd.cs.findbugs.annotations.Nullable;
  import java.nio.ByteBuffer;
  import java.util.concurrent.CompletionStage;
  
  /**
   * An authenticator that performs all of its operations synchronously, on the calling thread.
   *
   * <p>This is intended for simple implementations that are fast and lightweight enough, and do not
   * perform any blocking operations.
   */
  public interface SyncAuthenticator extends Authenticator {
  
    /**
     * Obtain an initial response token for initializing the SASL handshake.
     *
     * <p>{@link #initialResponse()} calls this and wraps the result in an immediately completed
     * future.
     *
     * @return The initial response to send to the server (which may be {@code null}). Note that, if
     *     the returned byte buffer is writable, the driver will <b>clear its contents</b> immediately
     *     after use (to avoid keeping sensitive information in memory); do not reuse the same buffer
     *     across multiple invocations. Alternatively, if the contents are not sensitive, you can make
     *     the buffer {@linkplain ByteBuffer#asReadOnlyBuffer() read-only} and safely reuse it.
     */
    @Nullable
    ByteBuffer initialResponseSync();
  
    /**
     * Evaluate a challenge received from the server.
     *
     * <p>{@link #evaluateChallenge(ByteBuffer)} calls this and wraps the result in an immediately
     * completed future.
     *
     * @param challenge the server's SASL challenge; may be {@code null}.
     * @return The updated SASL token (which may be {@code null} to indicate the client requires no
     *     further action). Note that, if the returned byte buffer is writable, the driver will
     *     <b>clear its contents</b> immediately after use (to avoid keeping sensitive information in
     *     memory); do not reuse the same buffer across multiple invocations. Alternatively, if the
     *     contents are not sensitive, you can make the buffer {@linkplain
     *     ByteBuffer#asReadOnlyBuffer() read-only} and safely reuse it.
     */
    @Nullable
    ByteBuffer evaluateChallengeSync(@Nullable ByteBuffer challenge);
  
    /**
     * Called when authentication is successful with the last information optionally sent by the
     * server.
     *
     * <p>{@link #onAuthenticationSuccess(ByteBuffer)} calls this, and then returns an immediately
     * completed future.
     *
     * @param token the information sent by the server with the authentication successful message.
     *     This will be {@code null} if the server sends no particular information on authentication
     *     success.
     */
    void onAuthenticationSuccessSync(@Nullable ByteBuffer token);
  
    @NonNull
    @Override
    default CompletionStage<ByteBuffer> initialResponse() {
      return CompletableFutures.wrap(this::initialResponseSync);
    }
  
    @NonNull
    @Override
    default CompletionStage<ByteBuffer> evaluateChallenge(@Nullable ByteBuffer challenge) {
      return CompletableFutures.wrap(() -> evaluateChallengeSync(challenge));
    }
  
    @NonNull
    @Override
    default CompletionStage<Void> onAuthenticationSuccess(@Nullable ByteBuffer token) {
      return CompletableFutures.wrap(
          () -> {
            onAuthenticationSuccessSync(token);
            return null;
          });
    }
  }
  