zebra: fix sockaddr_dl length assumptions (BZ#737)

Quagga makes bad assumptions about sockaddr_dl (on NetBSD, but possibly
on other systems as well).  Particularly, sizeof(struct sockaddr_dl)
returns a size that does not include the full sdl_data field, leading to
not enough data being copied.  This breaks IPv6 RAs in particular, as
a broken mac address from sockaddr_dl will be included in the packets.

From: Matthias-Christian Ott <ott@mirix.org>
Tested-by: Uwe Toenjes <6bone@6bone.informatik.uni-leipzig.de>
[further simplified + more comments]
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
5 files changed