Re: [PATCH] Ephemeral port randomization

[Skip Ford <skip.ford@xxxxxxxxxxx>]

Jon Parise wrote:
> On Wed, Apr 28, 2004 at 06:04:37PM -0400, Skip Ford wrote:
> 
> >  			/*
> >  			 * counting down
> >  			 */
> > +			if (ipport_randomized)
> > +				*lastport = first - 
> > +					    (arc4random() % (first - last));
> >  			count = first - last;
> >  
> >  			do {
> > @@ -341,6 +349,9 @@
> >  			/*
> >  			 * counting up
> >  			 */
> > +			if (ipport_randomized)
> > +				*lastport = first + 
> > +					    (arc4random() % (last - first));
> >  			count = last - first;
>   
> I don't purport to know this code at all, but, based on these snippets
> from the diff, wouldn't it make sense to compute 'count' before the
> 'ipport_randomized' test and then use 'count' in the '*lastport'
> calculation (instead of repeating the '(last - first)' arithmetic)?

Yeah, but that's not how FreeBSD does it.  I was planning to send a
follow-up patch if they applied the first.  I dislike patches that do
multiple things so I decided importing FreeBSD's version and optimizing
it a bit should be done separately, just like FreeBSD did bringing
in OpenBSD's version.

-- 
Skip