nexthop: add a identical helper function

Not all attributes of a nexthop are id attributes, e.g. the flags will contain state (LINKDOWN, DEAD) of the attached link about which the kernel will not send route updates. Likewise, the weight may not exist when processing an ECMP IPv6 route update which only contains a single nexthop. Since rtnl_nexthop isn't a first class cache object, we cannot use nl_object_identical(), so add a separate identical helper function which compares only fixed attributes. Signed-off-by: Jonas Gorski <[email protected]>
thom311 · May 14, 2024 · 8cf29d7 · 8cf29d7
1 parent 7cc72d1
commit 8cf29d7
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diff --git a/include/netlink/route/nexthop.h b/include/netlink/route/nexthop.h
@@ -30,6 +30,9 @@ extern int		rtnl_route_nh_compare(struct rtnl_nexthop *,
 					      struct rtnl_nexthop *,
 					      uint32_t, int);
 
+extern int		rtnl_route_nh_identical(struct rtnl_nexthop *,
+						struct rtnl_nexthop *);
+
 extern void		rtnl_route_nh_dump(struct rtnl_nexthop *,
 					   struct nl_dump_params *);
 

diff --git a/lib/route/nexthop.c b/lib/route/nexthop.c
@@ -136,6 +136,23 @@ int rtnl_route_nh_compare(struct rtnl_nexthop *a, struct rtnl_nexthop *b,
 	return diff;
 }
 
+/**
+ * Check if the fixed attributes of two nexthops are identical, and may
+ * only differ in flags or weight.
+ *
+ * @arg a		a nexthop
+ * @arg b		another nexthop
+ *
+ * @return true if both nexthop have equal attributes, otherwise false.
+ */
+int rtnl_route_nh_identical(struct rtnl_nexthop *a, struct rtnl_nexthop *b)
+{
+	return !rtnl_route_nh_compare(a, b,
+				      NH_ATTR_IFINDEX | NH_ATTR_REALMS |
+				      NH_ATTR_GATEWAY | NH_ATTR_NEWDST |
+				      NH_ATTR_VIA | NH_ATTR_ENCAP, 0);
+}
+
 static void nh_dump_line(struct rtnl_nexthop *nh, struct nl_dump_params *dp)
 {
 	struct nl_cache *link_cache;

diff --git a/libnl-route-3.sym b/libnl-route-3.sym
@@ -1328,4 +1328,5 @@ global:
 	rtnl_link_bridge_set_port_vlan_map_range;
 	rtnl_link_bridge_set_port_vlan_pvid;
 	rtnl_link_bridge_unset_port_vlan_map_range;
+	rtnl_route_nh_identical;
 } libnl_3_9;