ComputeCallback.cc

/*
 * Copyright 2003 Michael A. Marsh, Cornell University. All rights reserved.
 * This software is released under the modified BSD license.
 * See the file LICENSE in the top-level directory for details.
 */
//
// $Id: ComputeCallback.cc,v 1.3 2004/05/19 15:56:23 mmarsh Exp $
//
// $Log: ComputeCallback.cc,v $
// Revision 1.3  2004/05/19 15:56:23  mmarsh
// Added copyright and license statements.
//
// Revision 1.2  2003/11/04 22:31:45  mmarsh
// *** empty log message ***
//
//

#include "ComputeCallback.h"
#include "StateInfo.h"
#include "CODEX_Server/ServerState.h"

#include "CODEX_Exceptions/BignumExceptions.h"
#include "CODEX_Server/ServerExceptions.h"

#include "timing.h"

using namespace CODEX_APSS;

ComputeCallback::ComputeCallback( const LabelType& label ) :
   m_label( label ),
   m_completed( false )
{
}

ComputeCallback::~ComputeCallback()
{
}

bool
ComputeCallback::operator()( unsigned int server, CODEX_Quorum::Message* msg )
{
   if ( m_completed )
   {
      if ( 0 != msg ) delete msg;
      return true;
   }

   if ( 0 == msg )
   {
      return false;
   }

#ifdef TIMING
   ActiveTimer.start();
#endif
   CODEX_Server::ServerState* serverState =
      CODEX_Server::ServerState::instance();
   if ( 0 == serverState )
   {
      delete msg;
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return false;
   }

   StateInfo* stateInfo = StateInfo::instance();
   if ( 0 == stateInfo )
   {
      delete msg;
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return false;
   }

   // See if we're already in the next epoch.
   const unsigned long epoch = stateInfo->version( m_label.num().value() );
   const unsigned long version = m_label.version().value();
   if ( epoch >= version )
   {
      delete msg;
      m_completed = true;
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return true;
   }

   // Unmarshal the message.
   unsigned char* data = (unsigned char*)msg->buffer();
   int length = msg->length();

   if ( length < 2 )
   {
      delete msg;
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return false;
   }

   if ( stateInfo->domain() != data[0] )
   {
      delete msg;
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return false;
   }
   ++data;
   --length;

   if ( ( kComputedMsg | SignatureMask ) != data[0] )
   {
      delete msg;
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return false;
   }
   ++data;
   --length;

   SignedComputedMsg* signedResponse = new SignedComputedMsg;
   if ( 0 == signedResponse )
   {
      delete msg;
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return false;
   }
   if ( 0 == signedResponse->unmarshal( 0, &data, length ) )
   {
      delete msg;
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return false;
   }
   delete msg;

   // Make sure the response is valid.
   const ComputedMsg& response = signedResponse->message();

   unsigned int computor = response.computor().value();
   if ( computor != server )
   {
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return false;
   }

   if ( response.shareLabel() != m_label )
   {
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return false;
   }

   // Check the signature.
   BIGNUM * digest = 0;
   try
   {
      digest = response.digest( serverState->hashFunc() );
      if ( 0 == digest )
      {
         throw CODEX_Exceptions::BignumNullException( __FILE__ , __LINE__ );
      }
      if ( ! serverState->publicKey(server).verifySignature(
         signedResponse->signature(),
         digest ) )
      {
         throw CODEX_Server::SignatureVerificationFailedException( __FILE__ ,
                                                                   __LINE__ );
      }
      BN_free(digest);
   }
   catch ( ... )
   {
      if ( 0 != digest ) BN_free(digest);
#ifdef TIMING
      ActiveTimer.stop();
#endif
      return false;
   }

   // Add the response to the evidence set.
   m_evidence.append( signedResponse );

   CODEX_Quorum::QuorumSystem* qs = serverState->quorumSystem();
   if ( 0 == qs )
   {
#ifdef TIMING
      ActiveTimer.stop();
#endif
      throw CODEX_Server::NoQuorumSystemException( __FILE__ , __LINE__ );
   }

   if ( m_evidence.size() >= qs->quorumSize() )
   {
      // Compose the finished message.
      FinishedMsg fm( m_label.version(), m_label.id(), m_evidence );

      // Sign the finished message.
      BIGNUM * digest = 0;
      CODEX_Ciphers::RSASignature* signature = 0;
      try
      {
         const CODEX_Ciphers::HashFunction& hashFunc = serverState->hashFunc();
         digest = fm.digest( hashFunc );
         const CODEX_Ciphers::RSAPrivateKey& key = serverState->privateKey();
         signature = key.sign( digest );
         BN_free(digest);
         digest = 0;
         if ( 0 == signature )
         {
            throw CODEX_Exceptions::BignumNullException( __FILE__ , __LINE__ );
         }
      }
      catch ( ... )
      {
         if ( 0 != digest ) BN_free( digest );
         if ( 0 != signature ) delete signature;
#ifdef TIMING
         ActiveTimer.stop();
#endif
         throw;
      }
      SignedFinishedMsg signedFM( fm, *signature );
      delete signature;

      // Create the marshalled message.
      CODEX_Quorum::Message m;
      m.fill( serverState->hostNum() |
              CODEX_Server::ServerState::OutgoingMask );
      const unsigned char* seqNum = serverState->newSequenceNumber();
      m.fill( seqNum, CODEX_Server::ServerState::nMID );
      m.fill( stateInfo->domain() );
      m.fill( kFinishedMsg | SignatureMask );
      int length = signedFM.marshal(0);
      unsigned char* buffer = new unsigned char[length];
      unsigned char* pBuffer = buffer;
      signedFM.marshal(&pBuffer);
      m.fill( buffer, length );
      delete [] buffer;

      // Broadcast finished message.  No callback is registered.
      stateInfo->broadcast( m, 0 );

      m_completed = true;

#ifdef TIMING
      ComputeTimer[m_label.num().value()].stop();
#endif

   }

#ifdef TIMING
   ActiveTimer.stop();
#endif
   return true;
}

---