On Thu, Jul 07, 2011 at 03:36:02AM -0500, Stan Hoeppner wrote:
> I received a request to ignore IPv4 addresses as well in order to
> improve performance. But given the extensive IF loops it seems
> we'd only save something like a few picoseconds of CPU time (<30
> expressions processed). If that's actually critical I could add
> something like
>
> /^([0-9]{1,3}\.){3}[0-9]{1,3}$/ DUNNO
>
> Crude testing with postmap -q shows this matches only a naked
> dotted quad, but I'd rather not unleash it without more thorough
> testing, or confirmation from resident regex gurus that this will
> work as intended. Many rDNS strings contain a dotted quad, so we
> want to return DUNNO only for a naked dotted quad.
The anchors at both ends mean you are safe. You start with ^ and end
with $, so nothing else can sneak in between those.
A simpler expression to accomplish the same thing:
/^[0-9\.]$/ DUNNO
In English, that says: match a string which contains nothing but
numerals and dots. It matches nonsense strings such as "...", but
would be safe as per your intent to only match bare IP addresses.
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