Date: Wed, 26 Feb 2003 12:00:28 -0800 (PST) From: wpaul@FreeBSD.ORG (Bill Paul) To: julian@elischer.org (Julian Elischer) Cc: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/netgraph ng_fec.c Message-ID: <20030226200028.2584D37B401@hub.freebsd.org> In-Reply-To: <Pine.BSF.4.21.0302252331450.78515-100000@InterJet.elischer.org> from Julian Elischer at "Feb 25, 2003 11:41:02 pm"
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>
> On Tue, 25 Feb 2003, Bill Paul wrote:
>
> > wpaul 2003/02/25 22:38:54 PST
> >
> > Modified files:
> > sys/netgraph ng_fec.c
> > Log:
> > Attempt to make the ng_fec module play nice with BPF again. Things have
> > changed since this code was written:
> >
> > - The ng_ether_input_p hook only accepts two arguments now: the pointer
> > to the ether header structure is gone.
>
> The problem is that you should not be using ng_ether_input_p at all
> that is a private interface between ng_ether.c and if_ethersubr.c.
> You should be connecting a hook to ng_ether.c which will in turn
> use ng_ether_input_p.
[...]
Actually, there's a better (IMO) way. When I originally wrote this module,
I ended up using some netgraph features for two reasons: 1) using ngctl
saved me from having to write a separate feccontrol utility or mangling
ifconfig(8) to handle bundle configuration, and 2) I needed a way to snag
incoming frames. The ng_ether_input_p hook let me do that without having
to modify if_ethersubr.c myself, which I wanted to avoid. What I _really_
wanted to do was grab packets from the interfaces directly, before they
went into ether_input(), but I couldn't do that then.
I can, however, do it now. In 5.x, drivers call ifp->if_input rather than
using ether_input() directly, which makes it very simple to snarf frames
from them and massage them a bit before passing them on. I decided to
change ng_fec to work this way. As far as I'm concerned, it's a much
cleaner solution, and it avoids the collison with ng_ether.
-Bill
--
=============================================================================
-Bill Paul (510) 749-2329 | Senior Engineer, Master of Unix-Fu
wpaul@windriver.com | Wind River Systems
=============================================================================
"If stupidity were a handicap, you'd have the best parking spot."
=============================================================================
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