bgpd: don't try to reconcile AS4_PATH with NULL
bgp_attr_munge_as4_attrs would previously try to reintegrate an AS4_PATH
with a NULL AS_PATH, leading to a rather nasty SEGV. Let's go by
RFC6793 and treat missing AS_PATH as 0-length AS_PATH, which in turn
means discarding the AS4_PATH.
[NB: we don't actually stick to the actual rule, which is discarding
AS4_PATH if it's longer than AS_PATH; indeed we should probably fix that
too]
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/bgpd/bgp_attr.c b/bgpd/bgp_attr.c
index 1dce39b..cbf2902 100644
--- a/bgpd/bgp_attr.c
+++ b/bgpd/bgp_attr.c
@@ -1360,6 +1360,9 @@
/* need to reconcile NEW_AS_PATH and AS_PATH */
if (!ignore_as4_path && (attr->flag & (ATTR_FLAG_BIT( BGP_ATTR_AS4_PATH))))
{
+ if (!attr->aspath)
+ return BGP_ATTR_PARSE_PROCEED;
+
newpath = aspath_reconcile_as4 (attr->aspath, as4_path);
aspath_unintern (&attr->aspath);
attr->aspath = aspath_intern (newpath);