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.alipay.remoting.rpc.protocol;
  
  import com.alipay.remoting.codec.ProtocolCodeBasedDecoder;
  
  import io.netty.buffer.ByteBuf;
  
  /**
   * Rpc protocol decoder.
   *
   * @author tsui
   * @version $Id: RpcProtocolDecoder.java, v 0.1 2018-03-27 19:28 tsui Exp $
   */
  public class RpcProtocolDecoder extends ProtocolCodeBasedDecoder {
      public static final int MIN_PROTOCOL_CODE_WITH_VERSION = 2;
  
      public RpcProtocolDecoder(int protocolCodeLength) {
          super(protocolCodeLength);
      }
  
      @Override
      protected byte decodeProtocolVersion(ByteBuf in) {
          in.resetReaderIndex();
          if (in.readableBytes() >= protocolCodeLength + DEFAULT_PROTOCOL_VERSION_LENGTH) {
              byte rpcProtocolCodeByte = in.readByte();
              if (rpcProtocolCodeByte >= MIN_PROTOCOL_CODE_WITH_VERSION) {
                  return in.readByte();
              }
          }
          return DEFAULT_ILLEGAL_PROTOCOL_VERSION_LENGTH;
      }
  }