Netlink: Use route replace for IPv4 (8235c474) · Commits · 戴 / Bird

sysdep/linux/netlink.c

+27 −10

Original line number	Diff line number	Diff line
		@@ -69,6 +69,7 @@
		#define RTA_ENCAP 22
		#endif

		#define krt_ipv4(p) ((p)->af == AF_INET)
		#define krt_ecmp6(p) ((p)->af == AF_INET6)

		const int rt_default_ecmp = 16;
		@@ -1368,27 +1369,43 @@ nl_delete_rte(struct krt_proto p, rte e)
		return err;
		}

		static inline int
		nl_replace_rte(struct krt_proto p, rte e)
		{
		rta *a = e->attrs;
		return nl_send_route(p, e, NL_OP_REPLACE, a->dest, &(a->nh));
		}


		void
		krt_replace_rte(struct krt_proto p, net n, rte new, rte old)
		{
		int err = 0;

		/*
		* We could use NL_OP_REPLACE, but route replace on Linux has some problems:
		* We use NL_OP_REPLACE for IPv4, it has an issue with not checking for
		* matching rtm_protocol, but that is OK when dedicated priority is used.
		*
		* 1) Does not check for matching rtm_protocol
		* 2) Has broken semantics for IPv6 ECMP
		* 3) Crashes some kernel version when used for IPv6 ECMP
		* We do not use NL_OP_REPLACE for IPv6, as it has broken semantics for ECMP
		* and with some kernel versions ECMP replace crashes kernel. Would need more
		* testing and checks for kernel versions.
		*
		* So we use NL_OP_DELETE and then NL_OP_ADD. We also do not trust the old
		* route value, so we do not try to optimize IPv6 ECMP reconfigurations.
		* For IPv6, we use NL_OP_DELETE and then NL_OP_ADD. We also do not trust the
		* old route value, so we do not try to optimize IPv6 ECMP reconfigurations.
		*/

		if (krt_ipv4(p) && old && new)
		{
		err = nl_replace_rte(p, new);
		}
		else
		{
		if (old)
		nl_delete_rte(p, old);

		if (new)
		err = nl_add_rte(p, new);
		}

		if (err < 0)
		n->n.flags \|= KRF_SYNC_ERROR;

Admin message