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Date:      Fri, 09 Oct 1998 10:58:48 +0100
From:      Brian Somers <brian@Awfulhak.org>
To:        Bill Fenner <fenner@parc.xerox.com>
Cc:        Eivind Eklund <eivind@yes.no>, Brian Somers <brian@Awfulhak.org>, Kris Kennaway <kkennawa@physics.adelaide.edu.au>, current@FreeBSD.ORG
Subject:   Re: Improper sharing of modem bandwidth 
Message-ID:  <199810090958.KAA00774@woof.lan.awfulhak.org>
In-Reply-To: Your message of "Thu, 08 Oct 1998 15:21:21 PDT." <98Oct8.152124pdt.177476@crevenia.parc.xerox.com> 

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> In message <19981008211441.00286@follo.net> Eivind wrote:
> >#2 is probably the best (from the view of which possibilities it
> >gives), but I also suspect it is what would give most work (unless bpf
> >already can be used this way; then it would just be a question of
> >making PPP use it.)
> 
> [Jumping straight in where I know none of the context...]
> 
> 	i = bpf_filter(program, (u_char *)m, ip->ip_len, 0)
> 
> is all you need to do to run BPF program "program" on the packet in
> mbuf m.
> 
> The BPF program can return the packet's priority (i.e. by looking at
> TCP ports or IP TOS or whatever) and then you could order the packets
> in the queue by their priority.

Maybe this is over-flexible ?
It would be far easier (IMHO anyway) and wouldn't require any bpf 
code to create an ioctl something like

struct portlist {
  int nports;
  u_short port[1];
};

struct portlist *p = (struct portlist *)
  malloc(sizeof *p + (nports-1) * sizeof p->port);
p->nports = nports;
for (i = 0; i < nports; i++)
  p->port[i] = ...;
ioctl(tunfd, TIOCSETINTERACTIVEPORTS, p);

Closing the device would clear the list, and ppp could simply

#ifdef TIOCSETINTERACTIVEPORTS

to see if it needs to do this...

>   Bill

Having said all that, I suspect it would be easier to s/20/100/ as I 
originally suggested.  If you've got more than 100 packets queued at 
a given time, surely the TCP window is way to large.

-- 
Brian <brian@Awfulhak.org>, <brian@FreeBSD.org>, <brian@OpenBSD.org>
      <http://www.Awfulhak.org>;
Don't _EVER_ lose your sense of humour....



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