[ECOS] question about bridging code.

[ECOS] question about bridging code.

[bill guckel]

Hello,
I'm hoping someone can answer a question about the function
bridge_input() in net/tcpip/current/src/sys/net/if_bridge.c.
Specifically:
        /*
         * Unicast, make sure it's not for us.
         */
        for (ifl = LIST_FIRST(&sc->sc_iflist);ifl; ifl =
LIST_NEXT(ifl,next)) {
                if (ifl->ifp->if_type != IFT_ETHER)
                        continue;
                ac = (struct arpcom *)ifl->ifp;
                if (bcmp(ac->ac_enaddr, eh->ether_dhost, ETHER_ADDR_LEN) ==
0) {
                        if (ifl->bif_flags & IFBIF_LEARNING)
                                bridge_rtupdate(sc,
                                    (struct ether_addr *)&eh->ether_dhost,
                                    ifp, 0, IFBAF_DYNAMIC);
                        m->m_pkthdr.rcvif = ifl->ifp;
                        return (m);
                }

My question concerns the the passing of 'ether_dhost' to
'bridge_rtupdate()'.
Why not 'ether_shost' ?  This would seem to me (not a bridging expert) be a
more important address to learn.  Note that I may be using old code since
it's been a while since I took new source.

thanks,
bill guckel


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[ECOS] Re: question about bridging code.

[Daniel Néri]

"bill guckel" <bguckel@cisco.com> writes:

> I'm hoping someone can answer a question about the function
> bridge_input() in net/tcpip/current/src/sys/net/if_bridge.c.

[code snipped]

> My question concerns the the passing of 'ether_dhost' to
> 'bridge_rtupdate()'.  Why not 'ether_shost' ?  This would seem to me
> (not a bridging expert) be a more important address to learn.

It seems you are right.

> Note that I may be using old code since it's been a while since I
> took new source.

As far as I can see, this bug still exists in recent source. Though it
was fixed in the original code two years ago:

   http://www.openbsd.org/cgi-bin/cvsweb/src/sys/net/if_bridge.c.diff?r1=1.48&r2=1.49&f=h


Regards,

-- 
Daniel Néri, Sigicom AB, Sweden


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Re: [ECOS] Re: question about bridging code.

[Jonathan Larmour]

Daniel Néri wrote:
> 
> As far as I can see, this bug still exists in recent source. Though it
> was fixed in the original code two years ago:
> 
>    http://www.openbsd.org/cgi-bin/cvsweb/src/sys/net/if_bridge.c.diff?r1=1.48&r2=1.49&f=h

I've made this change.

Hm.. it seems the bridge stuff isn't in the FreeBSD stack. That would be 
something that needs to be added before we could ever drop the old stack :-|.

Jifl

Index: ChangeLog
===================================================================
RCS file: /cvs/ecos/ecos-opt/net/net/tcpip/current/ChangeLog,v
retrieving revision 1.41
diff -u -5 -p -r1.41 ChangeLog
--- ChangeLog	22 Dec 2002 11:03:52 -0000	1.41
+++ ChangeLog	30 Jan 2003 15:36:52 -0000
@@ -1,5 +1,11 @@
+2003-01-30  Jonathan Larmour  <jifl@eCosCentric.com>
+
+	* src/sys/net/if_bridge.c (bridge_input): Learn source host addr,
+	not dest host addr.
+	Fix pointed to by Daniel Néri.
+
  2002-12-14  Nick Garnett  <nickg@ecoscentric.com>

  	* src/sys/netinet/tcp_usrreq.c (tcp_usrreq): Rearranged ifndef on
  	PRU_SENSE case to keep the case in the switch and let it return a
  	sensible result. Otherwise a stat() on a socket causes a panic().
Index: src/sys/net/if_bridge.c
===================================================================
RCS file: /cvs/ecos/ecos-opt/net/net/tcpip/current/src/sys/net/if_bridge.c,v
retrieving revision 1.8
diff -u -5 -p -r1.8 if_bridge.c
--- src/sys/net/if_bridge.c	20 May 2002 22:25:20 -0000	1.8
+++ src/sys/net/if_bridge.c	30 Jan 2003 15:36:54 -0000
@@ -1168,11 +1168,11 @@ bridge_input(ifp, eh, m)
  			continue;
  		ac = (struct arpcom *)ifl->ifp;
  		if (bcmp(ac->ac_enaddr, eh->ether_dhost, ETHER_ADDR_LEN) == 0) {
  			if (ifl->bif_flags & IFBIF_LEARNING)
  				bridge_rtupdate(sc,
-				    (struct ether_addr *)&eh->ether_dhost,
+				    (struct ether_addr *)&eh->ether_shost,
  				    ifp, 0, IFBAF_DYNAMIC);
  			m->m_pkthdr.rcvif = ifl->ifp;
  			return (m);
  		}
  		if (bcmp(ac->ac_enaddr, eh->ether_shost, ETHER_ADDR_LEN) == 0) {

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