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From: Christopher Sedore <cmsedore@maxwell.syr.edu>
To: "'freebsd-net@freebsd.org'" <freebsd-net@freebsd.org>
Subject: bpf output bug fix
Date: Fri, 26 Mar 1999 19:56:53 -0500
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Since it appears that 2 people (3 if you count me :) agree that having
the kernel overwrite the source ethernet mac address on sends through
bpf is a bug, I fixed it (patch on the end).

Basically, rather than setting the dst->sa_family to AF_UNSPEC in the
bpfwrite call, I set it to AF_LINK instead.  I added glue to
if_ethersubr.c to handle AF_LINK, implying that this usage would not
conflict with anything else since it wasn't handled previously.  

It works as expected in my testing.

-Chris

diff -c -r sys/net/bpf.c /usr/src/sys/net/bpf.c
*** sys/net/bpf.c       Mon Dec  7 21:58:36 1998
--- /usr/src/sys/net/bpf.c      Fri Mar 26 19:52:37 1999
***************
*** 177,185 ****
                break;

        case DLT_EN10MB:
!               sockp->sa_family = AF_UNSPEC;
!               /* XXX Would MAXLINKHDR be better? */
!               hlen = sizeof(struct ether_header);
                break;

        case DLT_FDDI:
--- 177,184 ----
                break;

        case DLT_EN10MB:
!               sockp->sa_family = AF_LINK;
!               hlen = 0;
                break;

        case DLT_FDDI:
diff -c -r sys/net/if_ethersubr.c /usr/src/sys/net/if_ethersubr.c
*** sys/net/if_ethersubr.c      Tue Jan 12 12:07:00 1999
--- /usr/src/sys/net/if_ethersubr.c     Fri Mar 26 18:58:58 1999
***************
*** 336,360 ****
                type = eh->ether_type;
                break;

        default:
                printf("%s%d: can't handle af%d\n", ifp->if_name,
ifp->if_unit,
                        dst->sa_family);
                senderr(EAFNOSUPPORT);
        }

!       /*
!        * Add local net header.  If no space in first mbuf,
!        * allocate another.
!        */
!       M_PREPEND(m, sizeof (struct ether_header), M_DONTWAIT);
!       if (m == 0)
!               senderr(ENOBUFS);
!       eh = mtod(m, struct ether_header *);
!       (void)memcpy(&eh->ether_type, &type,
!               sizeof(eh->ether_type));
!       (void)memcpy(eh->ether_dhost, edst, sizeof (edst));
!       (void)memcpy(eh->ether_shost, ac->ac_enaddr,
!           sizeof(eh->ether_shost));

        /*
         * If a simplex interface, and the packet is being sent to our
--- 336,369 ----
                type = eh->ether_type;
                break;

+       case AF_LINK:
+               loop_copy = -1;
+               break;
+
        default:
                printf("%s%d: can't handle af%d\n", ifp->if_name,
ifp->if_unit,
                        dst->sa_family);
                senderr(EAFNOSUPPORT);
        }

!       if (dst->sa_family!=AF_LINK) {
!
!               /*
!                * Add local net header.  If no space in first mbuf,
!                * allocate another.
!                */
!               M_PREPEND(m, sizeof (struct ether_header), M_DONTWAIT);
!               if (m == 0)
!                       senderr(ENOBUFS);
!               eh = mtod(m, struct ether_header *);
!               (void)memcpy(&eh->ether_type, &type,
!                       sizeof(eh->ether_type));
!               (void)memcpy(eh->ether_dhost, edst, sizeof (edst));
!               (void)memcpy(eh->ether_shost, ac->ac_enaddr,
!                   sizeof(eh->ether_shost));
!       } else {
!               eh = mtod(m, struct ether_header *);
!       }

        /*
         * If a simplex interface, and the packet is being sent to our


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