bgpd: Late registration of Extended Nexthop should allow RA's to happen

When we have a late registration of the Extended Nexthop capability
for BGP and the peer already has nexthop information stored, go
through and enable RA on the important interfaces.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>

3 files changed, 60 insertions, 0 deletions

diff --git a/bgpd/bgp_nht.c b/bgpd/bgp_nht.c
index 8aa7798af4..0dce96f432 100644
--- a/bgpd/bgp_nht.c
+++ b/bgpd/bgp_nht.c
@@ -838,3 +838,48 @@ void bgp_nht_register_nexthops(struct bgp *bgp)
 		}
 	}
 }
+
+void bgp_nht_register_enhe_capability_interfaces(struct peer *peer)
+{
+	struct bgp *bgp;
+	struct bgp_node *rn;
+	struct bgp_nexthop_cache *bnc;
+	struct nexthop *nhop;
+	struct interface *ifp;
+	struct prefix p;
+
+	if (peer->ifp)
+		return;
+
+	bgp = peer->bgp;
+
+	if (!bgp->nexthop_cache_table[AFI_IP6])
+		return;
+
+	if (!sockunion2hostprefix(&peer->su, &p)) {
+		if (BGP_DEBUG(nht, NHT))
+			zlog_debug("%s: Unable to convert prefix to sockunion",
+				   __PRETTY_FUNCTION__);
+		return;
+	}
+
+	if (p.family != AF_INET6)
+		return;
+	rn = bgp_node_lookup(bgp->nexthop_cache_table[AFI_IP6], &p);
+
+	bnc = bgp_nexthop_get_node_info(rn);
+	if (!bnc)
+		return;
+
+	if (peer != bnc->nht_info)
+		return;
+
+	for (nhop = bnc->nexthop; nhop; nhop = nhop->next) {
+		ifp = if_lookup_by_index(nhop->ifindex,
+					 nhop->vrf_id);
+		zclient_send_interface_radv_req(zclient,
+						nhop->vrf_id,
+						ifp, true,
+						BGP_UNNUM_DEFAULT_RA_INTERVAL);
+	}
+}
diff --git a/bgpd/bgp_nht.h b/bgpd/bgp_nht.h
index 96dd915596..7daae93b25 100644
--- a/bgpd/bgp_nht.h
+++ b/bgpd/bgp_nht.h
@@ -88,4 +88,13 @@ extern void path_nh_map(struct bgp_path_info *path,
  */
 extern void bgp_nht_register_nexthops(struct bgp *bgp);
 
+/*
+ * When we have the the PEER_FLAG_CAPABILITY_ENHE flag
+ * set on a peer *after* it has been brought up we need
+ * to notice and setup the interface based RA,
+ * this code can walk the registered nexthops and
+ * register the important ones with zebra for RA.
+ */
+extern void bgp_nht_register_enhe_capability_interfaces(struct peer *peer);
+
 #endif /* _BGP_NHT_H */
diff --git a/bgpd/bgpd.c b/bgpd/bgpd.c
index 19384eec2f..0c26fa6720 100644
--- a/bgpd/bgpd.c
+++ b/bgpd/bgpd.c
@@ -3905,6 +3905,9 @@ static int peer_flag_modify(struct peer *peer, uint32_t flag, int set)
 		return 0;
 	}
 
+	if (set && flag == PEER_FLAG_CAPABILITY_ENHE)
+		bgp_nht_register_enhe_capability_interfaces(peer);
+
 	/*
 	 * Update peer-group members, unless they are explicitely overriding
 	 * peer-group configuration.
@@ -3928,6 +3931,9 @@ static int peer_flag_modify(struct peer *peer, uint32_t flag, int set)
 		/* Update flag on peer-group member. */
 		COND_FLAG(member->flags, flag, set != member_invert);
 
+		if (set && flag == PEER_FLAG_CAPABILITY_ENHE)
+			bgp_nht_register_enhe_capability_interfaces(member);
+
 		/* Execute flag action on peer-group member. */
 		if (action.type == peer_change_reset)
 			peer_flag_modify_action(member, flag);