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/*
 * Copyright 2019-present Open Networking Foundation
 * Copyright © 2020 camunda services GmbH ([email protected])
 *
 * Licensed 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 io.atomix.cluster.messaging.impl;

import static com.google.common.base.Preconditions.checkState;

import io.atomix.utils.net.Address;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import java.util.List;

/** Protocol version 2 message decoder. */
class MessageDecoderV2 extends AbstractMessageDecoder {

  private DecoderState currentState = DecoderState.READ_SENDER_HOST_LENGTH;
  private int senderHostLength;
  private String senderHost;
  private int senderPort;
  private Address senderAddress;
  private ProtocolMessage.Type type;
  private long messageId;
  private int contentLength;
  private byte[] content;
  private int subjectLength;

  @Override
  @SuppressWarnings({"squid:S128"}) // suppress switch fall through warning
  protected void decode(
      final ChannelHandlerContext context, final ByteBuf buffer, final List out)
      throws Exception {

    switch (currentState) {
      case READ_SENDER_HOST_LENGTH:
        if (buffer.readableBytes() < Short.BYTES) {
          return;
        }
        senderHostLength = buffer.readShort();
        currentState = DecoderState.READ_SENDER_HOST;
      case READ_SENDER_HOST:
        if (buffer.readableBytes() < senderHostLength) {
          return;
        }
        senderHost = readString(buffer, senderHostLength);
        currentState = DecoderState.READ_SENDER_PORT;
      case READ_SENDER_PORT:
        if (buffer.readableBytes() < Integer.BYTES) {
          return;
        }
        senderPort = buffer.readInt();
        senderAddress = Address.from(senderHost, senderPort);
        currentState = DecoderState.READ_TYPE;
      case READ_TYPE:
        if (buffer.readableBytes() < Byte.BYTES) {
          return;
        }
        type = ProtocolMessage.Type.forId(buffer.readByte());
        currentState = DecoderState.READ_MESSAGE_ID;
      case READ_MESSAGE_ID:
        try {
          messageId = readLong(buffer);
        } catch (final Escape e) {
          return;
        }
        currentState = DecoderState.READ_CONTENT_LENGTH;
      case READ_CONTENT_LENGTH:
        try {
          contentLength = readInt(buffer);
        } catch (final Escape e) {
          return;
        }
        currentState = DecoderState.READ_CONTENT;
      case READ_CONTENT:
        if (buffer.readableBytes() < contentLength) {
          return;
        }
        if (contentLength > 0) {
          // TODO: Perform a sanity check on the size before allocating
          content = new byte[contentLength];
          buffer.readBytes(content);
        } else {
          content = EMPTY_PAYLOAD;
        }

        switch (type) {
          case REQUEST:
            currentState = DecoderState.READ_SUBJECT_LENGTH;
            break;
          case REPLY:
            currentState = DecoderState.READ_STATUS;
            break;
          default:
            checkState(false, "Must not be here");
        }
        break;
      default:
        break;
    }

    switch (type) {
      case REQUEST:
        switch (currentState) {
          case READ_SUBJECT_LENGTH:
            if (buffer.readableBytes() < Short.BYTES) {
              return;
            }
            subjectLength = buffer.readShort();
            currentState = DecoderState.READ_SUBJECT;
          case READ_SUBJECT:
            if (buffer.readableBytes() < subjectLength) {
              return;
            }
            final String subject = readString(buffer, subjectLength);
            final ProtocolRequest message =
                new ProtocolRequest(messageId, senderAddress, subject, content);
            out.add(message);
            currentState = DecoderState.READ_TYPE;
            break;
          default:
            break;
        }
        break;
      case REPLY:
        switch (currentState) {
          case READ_STATUS:
            if (buffer.readableBytes() < Byte.BYTES) {
              return;
            }
            final ProtocolReply.Status status = ProtocolReply.Status.forId(buffer.readByte());
            final ProtocolReply message = new ProtocolReply(messageId, content, status);
            out.add(message);
            currentState = DecoderState.READ_TYPE;
            break;
          default:
            break;
        }
        break;
      default:
        checkState(false, "Must not be here");
    }
  }

  /** V2 decoder state. */
  enum DecoderState {
    READ_TYPE,
    READ_MESSAGE_ID,
    READ_SENDER_HOST_LENGTH,
    READ_SENDER_HOST,
    READ_SENDER_PORT,
    READ_SUBJECT_LENGTH,
    READ_SUBJECT,
    READ_STATUS,
    READ_CONTENT_LENGTH,
    READ_CONTENT
  }
}
    

    

    

            

    

            



    
    






    
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