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Date:      Fri, 24 Oct 2014 20:27:08 +0000
From:      bugzilla-noreply@freebsd.org
To:        freebsd-net@FreeBSD.org
Subject:   [Bug 194453] [dummynet] pipe config bw parameter is limited to 2Gbits per second
Message-ID:  <bug-194453-2472-dQu6jPacAT@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-194453-2472@https.bugs.freebsd.org/bugzilla/>
References:  <bug-194453-2472@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=194453

--- Comment #5 from Hiren Panchasara <hiren@FreeBSD.org> ---
(In reply to boba from comment #4)
> (In reply to Hiren Panchasara from comment #2)
> > (In reply to boba from comment #0)
> > > It's impossible to create "pipe" with bandwidth higher than 2Gbits per
> > > second. Possible due to "signed" type of variable.
> > > 
> > > # ipfw pipe 1 config bw 2700mbit/s
> > > ipfw: bandwidth too large
> > 
> > I think you are right that its overflowing because of "signed" type.
> > 
> > A simple change like this may fix the problem:
> > 
> > Index: dummynet.c
> > ===================================================================
> > --- dummynet.c  (revision 270969)
> > +++ dummynet.c  (working copy)
> > @@ -546,7 +546,7 @@
> >                 if_name[namelen] = '\0';
> >                 *bandwidth = 0;
> >         } else {        /* read bandwidth value */
> > -               int bw;
> > +               uint32_t bw;
> >                 char *end = NULL;
> >  
> >                 bw = strtoul(arg, &end, 0);
> 
> This patch will not work at all because of following check few lines after
> it:
> 
>                 if (bw < 0)
>                         errx(EX_DATAERR, "bandwidth too large");

This patch is incomplete. But the check above is needed exactly for the reason
of catching overflowing values. 

Afaik, a couple of things need to be done to make the patch complete:
1) make sure whatever datatype we use for bandwidth is uniform across entire
dummynet codebase. i.e. in struct dn_link inside netinet/ip_dummynet.h

2) It currently only handles Mb/s and b/s and not Gb/s while setting bandwidth.

If someone else doesn't beat me to it, I'll try to spend some time next week on
this.

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