ip,ip6: reject duplicate routes with different nexthops

Previously, adding a route that already existed would silently succeed if
exist_ok was true, even when the nexthop was different.

This behavior is incorrect, as the user expects either the same route with
the same nexthop to exist, or an error to be returned.

This patch ensures that an error is returned when a route exists with a
different nexthop, regardless of the exist_ok flag.

Signed-off-by: Maxime Leroy <[email protected]>

Author: maxime-leroy

modules/infra/control/gr_nh_control.h

@@ -39,6 +39,9 @@ struct hoplist {
 struct nexthop *
 nexthop_lookup(gr_nh_type_t type, uint16_t vrf_id, uint16_t iface_id, const void *addr);
 
+// Compare two nexthops, return True if the same, else False
+bool nexthop_equal(struct nexthop *nh1, struct nexthop *nh2);
+
 // Allocate a new nexthop from the global pool with the provided initial values.
 struct nexthop *
 nexthop_new(gr_nh_type_t type, uint16_t vrf_id, uint16_t iface_id, const void *addr);

modules/infra/control/nexthop.c

@@ -137,6 +137,24 @@ nexthop_new(gr_nh_type_t type, uint16_t vrf_id, uint16_t iface_id, const void *a
 	return nh;
 }
 
+bool nexthop_equal(struct nexthop *nh1, struct nexthop *nh2) {
+	if (nh1->vrf_id != nh2->vrf_id || nh1->iface_id != nh2->iface_id || nh1->type != nh2->type)
+		return false;
+
+	switch (nh1->type) {
+	case GR_NH_IPV4:
+	case GR_NH_SR6_IPV4:
+		return (memcmp(&nh1->ipv4, &nh2->ipv4, sizeof(nh1->ipv4)) == 0);
+	case GR_NH_IPV6:
+	case GR_NH_SR6_IPV6:
+		return (memcmp(&nh1->ipv6, &nh2->ipv6, sizeof(nh1->ipv6)) == 0);
+	default:
+		ABORT("invalid nexthop type %hhu", nh1->type);
+	}
+
+	return false;
+}
+
 struct pool_iterator {
 	nh_iter_cb_t user_cb;
 	void *priv;

modules/ip/control/route.c

@@ -131,6 +131,7 @@ int rib4_insert(
 ) {
 	struct rte_rib *rib = get_or_create_rib(vrf_id);
 	struct rte_rib_node *rn;
+	struct nexthop *_nh;
 	gr_rt_origin_t *o;
 	int ret;
 
@@ -140,8 +141,9 @@ int rib4_insert(
 		ret = -errno;
 		goto fail;
 	}
-	if (rib4_lookup_exact(vrf_id, ip, prefixlen) != NULL) {
-		ret = -EEXIST;
+	_nh = rib4_lookup_exact(vrf_id, ip, prefixlen);
+	if (_nh != NULL) {
+		ret = nexthop_equal(nh, _nh) ? -EEXIST : -EBUSY;
 		goto fail;
 	}
 

modules/ip6/control/route.c

@@ -144,6 +144,7 @@ int rib6_insert(
 	const struct rte_ipv6_addr *scoped_ip;
 	struct rte_ipv6_addr tmp;
 	struct rte_rib6_node *rn;
+	struct nexthop *_nh;
 	gr_rt_origin_t *o;
 	int ret;
 
@@ -153,8 +154,9 @@ int rib6_insert(
 		ret = -errno;
 		goto fail;
 	}
-	if (rib6_lookup_exact(vrf_id, iface_id, ip, prefixlen) != NULL) {
-		ret = -EEXIST;
+	_nh = rib6_lookup_exact(vrf_id, iface_id, ip, prefixlen);
+	if (_nh != NULL) {
+		ret = nexthop_equal(nh, _nh) ? -EEXIST : -EBUSY;
 		goto fail;
 	}