bridge(4) unicast behaviour

[Masao Uebayashi <uebayasi%gmail.com@localhost>]

I'm trying to use bridge(4) with tap(4) for emulator's network driver backend.
Multicast packets going from within emulator can reach addresses in the
bridge, but unicast packets "disappear" misteriously.  I've tracked this and
found a suspicious code fragment in sys/net/if_bridge.c:bridge_input():

   1494         /*
   1495          * Unicast.  Make sure it's not for us.
   1496          */
   1497         LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
   1498                 /* It is destined for us. */
   1499                 if (memcmp(CLLADDR(bif->bif_ifp->if_sadl), 
eh->ether_dhost,
   1500                     ETHER_ADDR_LEN) == 0
   1501 #if NCARP > 0
   1502                     || (bif->bif_ifp->if_carp && 
carp_ourether(bif->bif_ifp->if_carp,
   1503                         eh, IFT_ETHER, 0) != NULL)
   1504 #endif /* NCARP > 0 */
   1505                     ) {
   1506                         if (bif->bif_flags & IFBIF_LEARNING)
   1507                                 (void) bridge_rtupdate(sc,
   1508                                     eh->ether_shost, ifp, 0, 
IFBAF_DYNAMIC);
   1509                         m->m_pkthdr.rcvif = bif->bif_ifp;
   1510                         return (m);
   1511                 }
   1512
   1513                 /* We just received a packet that we sent out. */
   1514                 if (memcmp(CLLADDR(bif->bif_ifp->if_sadl), 
eh->ether_shost,
   1515                     ETHER_ADDR_LEN) == 0
   1516 #if NCARP > 0
   1517                     || (bif->bif_ifp->if_carp && 
carp_ourether(bif->bif_ifp->if_carp,
   1518                         eh, IFT_ETHER, 1) != NULL)
   1519 #endif /* NCARP > 0 */
   1520                     ) {
   1521                         m_freem(m);
   1522                         return (NULL);
   1523                 }
   1524         }

This is a loop looking for a destination interface in a given bridge.  The
first if () is to compare if_sadl with packet's eh->ether_dhost, which is
OK.  But the 2nd if (), which is comparing a given interface's address with
packet's source address (eh->ether_shost), happens to match, the packet just
"disappears".  I don't think that this is intended behaviour.

(Think of the case that if the next interface (bif) in the list is the inteface
which has the matching destination address.  This LIST_FOREACH() behaviour
depends on the order of interfaces in the list.)

Masao