code: /**
  Copyright (c) 2007-2013 Alysson Bessani, Eduardo Alchieri, Paulo Sousa, and the authors indicated in the @author tags
  
  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 bftsmart.tom.util;
  
  import java.io.ByteArrayInputStream;
  import java.io.DataInputStream;
  import java.nio.ByteBuffer;
  import java.util.Random;
  
  import bftsmart.reconfiguration.ServerViewController;
  import bftsmart.tom.core.messages.TOMMessage;
  import org.apache.log4j.Logger;
  
  
  /**
   * Batch format: N_MESSAGES(int) + N_MESSAGES*[MSGSIZE(int),MSG(byte)] +
   *               TIMESTAMP(long) + N_NONCES(int) + NONCES(byte[])
   *
   */
  public final class BatchReader {
      private final static Logger logger = Logger.getLogger(BatchReader.class);
      private ByteBuffer proposalBuffer;
      private boolean useSignatures;
  
      /** wrap buffer */
      public BatchReader(byte[] batch, boolean useSignatures) {
          proposalBuffer = ByteBuffer.wrap(batch);
          this.useSignatures = useSignatures;
      }
  
      public TOMMessage[] deserialiseRequests(ServerViewController controller) {
  
          //obtain the timestamps to be delivered to the application
          long timestamp = proposalBuffer.getLong();
  
          int numberOfNonces = proposalBuffer.getInt();
          
          long seed = 0;
  
          Random rnd = null;
          if(numberOfNonces > 0){
              seed = proposalBuffer.getLong();
              rnd = new Random(seed);
          }
          else numberOfNonces = 0; // make sure the value is correct
          
          int numberOfMessages = proposalBuffer.getInt();
  
          TOMMessage[] requests = new TOMMessage[numberOfMessages];
  
          for (int i = 0; i < numberOfMessages; i++) {
              //read the message and its signature from the batch
              int messageSize = proposalBuffer.getInt();
  
              byte[] message = new byte[messageSize];
              proposalBuffer.get(message);
  
              byte[] signature = null;
              if(useSignatures){
                  signature = new byte[TOMUtil.getSignatureSize(controller)];
                  proposalBuffer.get(signature);
              }
              //obtain the nonces to be delivered to the application
              byte[] nonces = new byte[numberOfNonces];
              if (nonces.length > 0) {
                  rnd.nextBytes(nonces);
              }
              try {
                  DataInputStream ois = new DataInputStream(new ByteArrayInputStream(message));
                  TOMMessage tm = new TOMMessage();
                  tm.rExternal(ois);
  
                  tm.serializedMessage = message;
                  tm.serializedMessageSignature = signature;
                  tm.numOfNonces = numberOfNonces;
                  tm.seed = seed;
                  tm.timestamp = timestamp;
                  requests[i] = tm;
  
              } catch (Exception e) {
  //                e.printStackTrace(System.out);
                  logger.error(e);
              }
          }
          return requests;
      }
  }
  