ldpd: fix processing of redistributed routes

Commit 5048fe changed the way zebra behave when a route is updated. Now,
whenever a route is changed, zebra advertises its new version without
withdrawing the old one. This patch adapts ldpd to understand this new
behavior. After processing a ZEBRA_REDISTRIBUTE_IPV[46]_ADD message,
we need to check for nexthops that were removed and, for each of them
(if any), withdraw the associated labels from zebra.

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

5 files changed, 42 insertions, 1 deletions

diff --git a/ldpd/lde.c b/ldpd/lde.c
index ae29ef6a7..904d0f8d9 100644
--- a/ldpd/lde.c
+++ b/ldpd/lde.c
@@ -406,6 +406,7 @@ lde_dispatch_parent(struct thread *thread)
 
 		switch (imsg.hdr.type) {
 		case IMSG_NETWORK_ADD:
+		case IMSG_NETWORK_ADD_END:
 		case IMSG_NETWORK_DEL:
 			if (imsg.hdr.len != IMSG_HEADER_SIZE + sizeof(kr)) {
 				log_warnx("%s: wrong imsg len", __func__);
@@ -433,6 +434,9 @@ lde_dispatch_parent(struct thread *thread)
 				lde_kernel_insert(&fec, kr.af, &kr.nexthop,
 				    kr.priority, kr.flags & F_CONNECTED, NULL);
 				break;
+			case IMSG_NETWORK_ADD_END:
+				lde_kernel_reevaluate(&fec);
+				break;
 			case IMSG_NETWORK_DEL:
 				lde_kernel_remove(&fec, kr.af, &kr.nexthop,
 				    kr.priority);
diff --git a/ldpd/lde.h b/ldpd/lde.h
index 0fce5565a..cf8f2129a 100644
--- a/ldpd/lde.h
+++ b/ldpd/lde.h
@@ -102,7 +102,9 @@ struct fec_nh {
 	union ldpd_addr		 nexthop;
 	uint32_t		 remote_label;
 	uint8_t			 priority;
+	uint8_t			 flags;
 };
+#define F_FEC_NH_NEW		0x01
 
 struct fec_node {
 	struct fec		 fec;
@@ -167,6 +169,7 @@ void		 lde_kernel_insert(struct fec *, int, union ldpd_addr *,
 		    uint8_t, int, void *);
 void		 lde_kernel_remove(struct fec *, int, union ldpd_addr *,
 		    uint8_t);
+void		 lde_kernel_reevaluate(struct fec *);
 void		 lde_check_mapping(struct map *, struct lde_nbr *);
 void		 lde_check_request(struct map *, struct lde_nbr *);
 void		 lde_check_release(struct map *, struct lde_nbr *);
diff --git a/ldpd/lde_lib.c b/ldpd/lde_lib.c
index 568761bd6..c72a25985 100644
--- a/ldpd/lde_lib.c
+++ b/ldpd/lde_lib.c
@@ -334,8 +334,11 @@ lde_kernel_insert(struct fec *fec, int af, union ldpd_addr *nexthop,
 	fn = (struct fec_node *)fec_find(&ft, fec);
 	if (fn == NULL)
 		fn = fec_add(fec);
-	if (fec_nh_find(fn, af, nexthop, priority) != NULL)
+	fnh = fec_nh_find(fn, af, nexthop, priority);
+	if (fnh != NULL) {
+		fnh->flags |= F_FEC_NH_NEW;
 		return;
+	}
 
 	if (fn->fec.type == FEC_TYPE_PWID)
 		fn->data = data;
@@ -352,6 +355,7 @@ lde_kernel_insert(struct fec *fec, int af, union ldpd_addr *nexthop,
 	}
 
 	fnh = fec_nh_add(fn, af, nexthop, priority);
+	fnh->flags |= F_FEC_NH_NEW;
 	lde_send_change_klabel(fn, fnh);
 
 	switch (fn->fec.type) {
@@ -402,6 +406,31 @@ lde_kernel_remove(struct fec *fec, int af, union ldpd_addr *nexthop,
 	}
 }
 
+/*
+ * Whenever a route is changed, zebra advertises its new version without
+ * withdrawing the old one. So, after processing a ZEBRA_REDISTRIBUTE_IPV[46]_ADD
+ * message, we need to check for nexthops that were removed and, for each of
+ * them (if any), withdraw the associated labels from zebra.
+ */
+void
+lde_kernel_reevaluate(struct fec *fec)
+{
+	struct fec_node		*fn;
+	struct fec_nh		*fnh, *safe;
+
+	fn = (struct fec_node *)fec_find(&ft, fec);
+	if (fn == NULL)
+		return;
+
+	LIST_FOREACH_SAFE(fnh, &fn->nexthops, entry, safe) {
+		if (fnh->flags & F_FEC_NH_NEW)
+			fnh->flags &= ~F_FEC_NH_NEW;
+		else
+			lde_kernel_remove(fec, fnh->af, &fnh->nexthop,
+			    fnh->priority);
+	}
+}
+
 void
 lde_check_mapping(struct map *map, struct lde_nbr *ln)
 {
diff --git a/ldpd/ldp_zebra.c b/ldpd/ldp_zebra.c
index 6c4137d30..b796b6f6d 100644
--- a/ldpd/ldp_zebra.c
+++ b/ldpd/ldp_zebra.c
@@ -438,6 +438,10 @@ ldp_zebra_read_route(int command, struct zclient *zclient, zebra_size_t length,
 		}
 	}
 
+	if (command == ZEBRA_REDISTRIBUTE_IPV4_ADD ||
+	    command == ZEBRA_REDISTRIBUTE_IPV6_ADD)
+		main_imsg_compose_lde(IMSG_NETWORK_ADD_END, 0, &kr, sizeof(kr));
+
 	return (0);
 }
 
diff --git a/ldpd/ldpd.h b/ldpd/ldpd.h
index 9601f25f7..b94794208 100644
--- a/ldpd/ldpd.h
+++ b/ldpd/ldpd.h
@@ -117,6 +117,7 @@ enum imsg_type {
 	IMSG_NEIGHBOR_UP,
 	IMSG_NEIGHBOR_DOWN,
 	IMSG_NETWORK_ADD,
+	IMSG_NETWORK_ADD_END,
 	IMSG_NETWORK_DEL,
 	IMSG_SOCKET_IPC,
 	IMSG_SOCKET_NET,