Subject: Re: Question about libpcap
To: Gerald Lee <glee@force10networks.com>
From: David Maxwell <david@crlf.net>
List: tech-net
Date: 07/20/2007 13:07:13
On Fri, Jul 20, 2007 at 09:58:03AM -0700, Gerald Lee wrote:
> David Maxwell Thursday, July 19, 2007 7:47 PM
> >When you say 'the parser' - do you mean the bpf lex/yacc machine?
>
> Yes, sorry to be less than complete.
Quite all right. The bpf virtual machine is a packet parser, so I was
trying to figure out if you meant rules or packets... rules. Got it.
> >I'm not following the description of the problem here.
> >pcap_compile_nopcap takes the filter program as the str argument, and
> >shouldn't be touching any file handles...
>
> Once more, I'm working partially off of our engineers description of
> his interaction with it. It appears to be a an assumption that in
> the non-interactive case, yyin will be null or something like that.
I wouldn't expect an assumption like that to exist in the code, since
you can define whatever input mechanism you like...
Here's a page that describes the traditional hackey method for not using
STDIN, and a cleaner method supported by flex. Comparing these to what
you're using right now to set up string based input should give a hint
as to what's wrong.
http://pintday.org/kjell/hack/lex
--
David Maxwell, david@vex.net|david@maxwell.net -->
An organization gets what it rewards.
- Perry Metzger