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 io.netty.buffer.ByteBuf;
  import io.netty.buffer.Unpooled;
  
  import org.apache.spark.network.buffer.NettyManagedBuffer;
  import org.apache.spark.network.protocol.Encoders;
  import org.apache.spark.network.protocol.AbstractMessage;
  
  /**
   * Encodes a Sasl-related message which is attempting to authenticate using some credentials tagged
   * with the given appId. This appId allows a single SaslRpcHandler to multiplex different
   * applications which may be using different sets of credentials.
   */
  class SaslMessage extends AbstractMessage {
  
    /** Serialization tag used to catch incorrect payloads. */
    private static final byte TAG_BYTE = (byte) 0xEA;
  
    public final String appId;
  
    SaslMessage(String appId, byte[] message) {
      this(appId, Unpooled.wrappedBuffer(message));
    }
  
    SaslMessage(String appId, ByteBuf message) {
      super(new NettyManagedBuffer(message), true);
      this.appId = appId;
    }
  
    @Override
    public Type type() { return Type.User; }
  
    @Override
    public int encodedLength() {
      // The integer (a.k.a. the body size) is not really used, since that information is already
      // encoded in the frame length. But this maintains backwards compatibility with versions of
      // RpcRequest that use Encoders.ByteArrays.
      return 1 + Encoders.Strings.encodedLength(appId) + 4;
    }
  
    @Override
    public void encode(ByteBuf buf) {
      buf.writeByte(TAG_BYTE);
      Encoders.Strings.encode(buf, appId);
      // See comment in encodedLength().
      buf.writeInt((int) body().size());
    }
  
    public static SaslMessage decode(ByteBuf buf) {
      if (buf.readByte() != TAG_BYTE) {
        throw new IllegalStateException("Expected SaslMessage, received something else"
          + " (maybe your client does not have SASL enabled?)");
      }
  
      String appId = Encoders.Strings.decode(buf);
      // See comment in encodedLength().
      buf.readInt();
      return new SaslMessage(appId, buf.retain());
    }
  }
  