bgpd: support evpn nd ext community

EVPN ND ext community support NA flag R-bit, to have proxy ND.

Set R-bit in EVPN NA if a given router is default gateway or there is a
local
router attached, which can be determine based on local neighbor entry.

Implement BGP ext community attribute to generate and parse  R-bit and
pass along zebra to program neigh entry in kernel.

Upon receiving MAC/IP update with community type 0x06 and sub_type 0x08,
pass the R-bit to zebra to program neigh entry.

Set NTF_ROUTER in neigh entry and inform kernel to do proxy NA for EVPN.

Ref:
https://tools.ietf.org/html/draft-ietf-bess-evpn-na-flags-01

Ticket:CM-21712, CM-21711
Reviewed By:
Testing Done:
Configure Local vni enabled L3 Gateway, which would act as router,
checked
show evpn arp-cache vni x ip <ip of svi> on originated and remote VTEPs.
"Router" flag is set.

Signed-off-by: Chirag Shah <chirag@cumulusnetworks.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/bgpd/bgp_attr_evpn.c b/bgpd/bgp_attr_evpn.c
index 14ff01ada5..88e520fdc5 100644
--- a/bgpd/bgp_attr_evpn.c
+++ b/bgpd/bgp_attr_evpn.c
@@ -210,6 +210,39 @@ uint32_t bgp_attr_mac_mobility_seqnum(struct attr *attr, uint8_t *sticky)
 	return 0;
 }
 
+/*
+ * return true if attr contains router flag extended community
+ */
+void bgp_attr_evpn_na_flag(struct attr *attr, uint8_t *router_flag)
+{
+	struct ecommunity *ecom;
+	int i;
+	uint8_t val;
+
+	ecom = attr->ecommunity;
+	if (!ecom || !ecom->size)
+		return;
+
+	/* If there is a evpn na extendd community set router_flag */
+	for (i = 0; i < ecom->size; i++) {
+		uint8_t *pnt;
+		uint8_t type, sub_type;
+
+		pnt = (ecom->val + (i * ECOMMUNITY_SIZE));
+		type = *pnt++;
+		sub_type = *pnt++;
+
+		if (type == ECOMMUNITY_ENCODE_EVPN &&
+		    sub_type == ECOMMUNITY_EVPN_SUBTYPE_ND) {
+			val = *pnt++;
+			if (val & ECOMMUNITY_EVPN_SUBTYPE_ND_ROUTER_FLAG) {
+				*router_flag = 1;
+				break;
+			}
+		}
+	}
+}
+
 /* dst prefix must be AF_INET or AF_INET6 prefix, to forge EVPN prefix */
 extern int bgp_build_evpn_prefix(int evpn_type, uint32_t eth_tag,
 				 struct prefix *dst)