RE: [Quickfix-developers] Field with embedded null character

[Yihu F. <Yih...@re...>]

Hi,

Actually I am thinking what if a FIX engine sends a FIX message which
has embedded null character. After the message read off the socket
(which is a character array), the rest of the code is using STL string
to represent the message. A null character will basically truncate the
string.

For example, this message with an extra null in 55=3DIBM<null><soh>
=20
8=3DFIX.4.0<soh>9=3D71<soh>35=3DD<soh>49=3DFIRM0<soh>56=3DFIRM1<soh>11=3D12=
3<soh>21=3D
1<soh>38=3D456<soh>40=3D2<soh>44=3D789<soh>54=3D1<soh>55=3DIBM<null><soh>59=
=3D0<soh>
10=3D157<soh>

In Parser::readFixMessage, extractLength will extract the length of the
message which is larger than m_buffer.size() because m_buffer is a
string and the null character terminate the string in the middle of the
message.

This will in turn drop the whole character buffer in
ThreadedSocketConnection::readQueue() even if the buffer could have a
multiple FIX message in it.

There is no exception or error log in such a scenario.

How should QF handle this case?

Thanks.

-Yihu



-----Original Message-----
From: Caleb Epstein [mailto:cal...@gm...]=20
Sent: Thursday, October 28, 2004 9:06 AM
To: Yihu Fang
Cc: qui...@li...; Oren Miller
Subject: Re: [Quickfix-developers] Field with embedded null character

On Wed, 27 Oct 2004 21:23:04 -0400, Yihu Fang <yih...@re...>
wrote:
> However, in QuickFIX message constructor, it takes string as the
parameter.
> It will throw an invalid message exception because it thinks the
string is
> truncated at the null character and cannot find the Tag 10.=20

Make sure you construct the string you pass to the Message constructor
properly.  The std::string constructor can take a const char* with or
without a length.  If you don't pass the length, it'll stop at the
first embedded \0 and you'll end up with a truncated message.

That said, it does seem that QuickFIX has a bug in the message
serialization code when dealing with fields having embedded \0 bytes:

#include <quickfix/Message.h>
#include <iostream>

using namespace FIX; using namespace std;

int main () {
  Message m;
  m.setField (1000, string ("one\0", 4));
  cout << m.toString () << endl;
  cout << m.getField (1000) << endl;
}

Gives the output (where ^A =3D ASCII SOH and \0 is an ASCII NULL)

9=3D10^A1000=3D one^A10=3D057^A
one\0

Note extra space and lack of \0 for serialized message form.

--=20
Caleb Epstein
cal...@gm...



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