On 8 Dec 2003, Scott A Crosby wrote:
> On Mon, 08 Dec 2003 16:43:15 -0500, Matt Kettler <[EMAIL PROTECTED]> writes:
>
> > Or *, to catch more than one obfuscating character..
> >
> > ie: V...i..a.gr..a
> >
> > As I suggested in my email, there's lots of combinations that spammers
> > can do to avoid the original rule. There's also lots of ways to
> > construct the rule to get a broader hit-base, at the expense of
> > greater processing time.
>
> In theory, this isn't that much additional matching time, especially
> with an automata. In practice though, these sorts of rules will kill
> performance because Perl cannot apply the literal optimization,
> especially if they're applied widely. (There's more than just Vxxxxx
> -- most of the phrase rules need this sort of treatment.)
>
> Scott
Scott,
If it's a bounded wild-card (".{0,6}") as opposed to unbounded (".*")
is it less of a hit? (IE reasonable thing to do).
Are there any reasonably simple ways to do this with out killing things?
(EG .? == OK, .* == BAD, .{0,n} == acceptable, for small values of 'n')
Are there any studies of the Perl matching engine for efficiency
and rules-of-thumb?
Dave
--
Dave Funk University of Iowa
<dbfunk (at) engineering.uiowa.edu> College of Engineering
319/335-5751 FAX: 319/384-0549 1256 Seamans Center
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