Re: [Quickfix-developers] Contributing code

[Howard E. <ho...@ex...>]

I have made minor modifications to the qf lib to fix the following two
issues.  These changes have been tested and running on our servers
without problems.  I hope they can be added for future release.

thanks,

Howard

Issues:

1.) A second socket connection (to acceptor) made using a SessionID
already in uses causes the library to behave erratically.
2.) FIX Field 141 (ResetSeqNumFlag) on the Logon Message is ignored.


Issue #1
If a FIX client connects to the QuickFIX acceptor, using a SessionID
already in use, it fouls the state of the Session object associated with
that SessionID resulting in the Second connection being dropped, but the
first connection no longer calling events on the Application class.  It
is also impossible to prevent the second connection from being accepted
within the Application class override, because the OnLogon event is
never raised. 

Fix
My fix for this solution is to disconnect an existing connection when a
second connection with a "connected" SessionID comes in.  The first
connection is disconnected (App gets LogOut event) and the second
connection is accepted (App gets Logon event).

Modules Affected: (Acceptor.cpp, SocketConnection.cpp)

Acceptor.cpp
======================================
Method:  Acceptor::getSession, at line 149
Adding the disconnect line will cause any existing session using that 
SessionID
to be LoggedOff and the socket connection to be closed.  If there is no 
connection currently using that SessionID the call is harmless.

Change 
---------------
    Sessions::iterator i = m_sessions.find( sessionID );
    if ( i != m_sessions.end() )
    {
      i->second->setResponder( &responder );
      return i->second;
    }

To
---------------
    Sessions::iterator i = m_sessions.find( sessionID );
    if ( i != m_sessions.end() )
    {
      // ADD THE NEXT LINE
      i->second->disconnect();
      i->second->setResponder( &responder );
      return i->second;
    }

SocketConnection.cpp
======================================
Method:  SocketConnection::disconnect
This clearing the Session ptr of a SocketConnection prevents
the Session disconnect method from being called twice (called
the first time in the Acceptor::getSession method) when the
SocketMonitor drop is processed.

Change 
---------------
void SocketConnection::disconnect()
{ QF_STACK_PUSH(SocketConnection::disconnect)

  if ( m_pMonitor )
    m_pMonitor->drop( m_socket );

  QF_STACK_POP
}

To
---------------
void SocketConnection::disconnect()
{ QF_STACK_PUSH(SocketConnection::disconnect)
 // ADD THE NEXT LINE
  m_pSession = 0;
  if ( m_pMonitor )
    m_pMonitor->drop( m_socket );

  QF_STACK_POP
}

Issue #2
The ResetSeqNumFlag tag is ignored when Sessions logon to quickfix
server.

Fix
Add code to the Session::nextLogon and the Session::generateLogon
methods
to handle the request.

I list the diffs, followed by the full modified methods
Modules Affected: (Session.cpp)

Session.cpp
======================================
Method: Session::nextLogon

Remove
------------
<   bool verified = verify( logon, false, true );
Add
------------
>   ResetSeqNumFlag resetSeqNumFlag(false);
>   logon.getField(resetSeqNumFlag);
> 
>   bool verified = verify( logon, false, (false ==
resetSeqNumFlag.getValue()) );
213a217,224
>   if (resetSeqNumFlag.getValue() == true)
>   {
>       m_state.onEvent( "Received Logon with SequenceReset FROM: "
>                                               +
IntConvertor::convert(getExpectedTargetNum()) + 
>                                               " TO: 1" );
>       m_state.store()->reset();
>   }
> 

Method: Session::generateLogon
Add
------------
544a556,563
> 
>   if (aLogon.isSetField(FIELD::ResetSeqNumFlag))
>   {
>     ResetSeqNumFlag resetSeqNumFlag(false);
>       aLogon.getField(resetSeqNumFlag);
>     logon.setField(resetSeqNumFlag);
>   }
> 



void Session::nextLogon( const Message& logon )
{ QF_STACK_PUSH(Session::nextLogon)

  if ( m_state.shouldSendLogon() )
  {
    m_state.onEvent( "Received logon response before sending request" );
    disconnect();
    return ;
  }

  SenderCompID senderCompID;
  TargetCompID targetCompID;
  logon.getHeader().getField( senderCompID );
  logon.getHeader().getField( targetCompID );

  ResetSeqNumFlag resetSeqNumFlag(false);
  logon.getField(resetSeqNumFlag);

  bool verified = verify( logon, false, (false ==
resetSeqNumFlag.getValue()) );
  if ( isCorrectCompID( senderCompID, targetCompID ) )
    m_state.receivedLogon( true );
  if ( !verified ) return ;

  if ( !m_state.initiate() )
  {
    logon.getField( m_state.heartBtInt() );
    m_state.onEvent( "Received logon request" );
    generateLogon( logon );
    m_state.onEvent( "Responding to logon request" );
  }
  else
    m_state.onEvent( "Received logon response" );

  if (resetSeqNumFlag.getValue() == true)
  {
    m_state.onEvent( "Received Logon with SequenceReset FROM: "
                        + IntConvertor::convert(getExpectedTargetNum())
+
                        " TO: 1" );
    m_state.store()->reset();
  }

  MsgSeqNum msgSeqNum;
  logon.getHeader().getField( msgSeqNum );
  if ( isTargetTooHigh( msgSeqNum ) )
  {
    doTargetTooHigh( logon );
  }
  else
  {
    m_state.incrNextTargetMsgSeqNum();
    nextQueued();
  }

  if ( isLoggedOn() )
    m_application.onLogon( m_sessionID );

  QF_STACK_POP
}



void Session::generateLogon( const Message& aLogon )
{ QF_STACK_PUSH(Session::generateLogon)

  Message logon;
  EncryptMethod encryptMethod;
  HeartBtInt heartBtInt;
  logon.setField( EncryptMethod( 0 ) );
  aLogon.getField( heartBtInt );
  logon.getHeader().setField( MsgType( "A" ) );
  logon.setField( heartBtInt );

  if (aLogon.isSetField(FIELD::ResetSeqNumFlag))
  {
    ResetSeqNumFlag resetSeqNumFlag(false);
    aLogon.getField(resetSeqNumFlag);
    logon.setField(resetSeqNumFlag);
  }

  fill( logon.getHeader() );
  sendRaw( logon );
  m_state.sentLogon( true );

  QF_STACK_POP
}


On Mon, 2003-11-17 at 23:24,
qui...@li... wrote:


> 
> --__--__--
> 
> Message: 2
> Subject: Re: [Quickfix-developers] Contributing code
> Date: Mon, 17 Nov 2003 12:02:23 -0600
> From: "Miller, Oren" <OM...@ri...>
> To: <ho...@ex...>,
> 	<qui...@li...>
> 
> Post them to this list.
> 
> --------------------------
> Sent from my BlackBerry Wireless Handheld
> 
> 
> -----Original Message-----
> From: Howard Engelhart <ho...@ex...>
> To: QuickFIX Questions <qui...@li...>
> Sent: Mon Nov 17 11:43:03 2003
> Subject: [Quickfix-developers] Contributing code
> 
> I have made a couple of minor changes to the QuickFIX lib that I would =
> like to submit for review for possible inclusion into the next version =
> of QuickFIX.  Is that possible?  If so how should I proceed?
> 
> Thanks,
> 
> Howard
> ho...@ex...
>