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>
diff --git a/lib/if.h b/lib/if.h
index 841ce51..2116e12 100644
--- a/lib/if.h
+++ b/lib/if.h
@@ -103,7 +103,13 @@
/* Hardware address. */
#ifdef HAVE_STRUCT_SOCKADDR_DL
- struct sockaddr_dl sdl;
+ union {
+ /* note that sdl_storage is never accessed, it only exists to make space.
+ * all actual uses refer to sdl - but use sizeof(sdl_storage)! this fits
+ * best with C aliasing rules. */
+ struct sockaddr_dl sdl;
+ struct sockaddr_storage sdl_storage;
+ };
#else
unsigned short hw_type;
u_char hw_addr[INTERFACE_HWADDR_MAX];