iplink: bridge: add support for IFLA_BR_MCAST_ROUTER

This patch implements support for the IFLA_BR_MCAST_ROUTER attribute
in iproute2 so it can change the multicast router value.
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

ip/iplink_bridge.c

@@ -33,6 +33,7 @@ static void print_explain(FILE *f)
 		"                  [ vlan_filtering VLAN_FILTERING ]\n"
 		"                  [ vlan_protocol VLAN_PROTOCOL ]\n"
 		"                  [ vlan_default_pvid VLAN_DEFAULT_PVID ]\n"
+		"                  [ mcast_router MULTICAST_ROUTER ]\n"
 		"\n"
 		"Where: VLAN_PROTOCOL := { 802.1Q | 802.1ad }\n"
 	);
@@ -140,6 +141,14 @@ static int bridge_parse_opt(struct link_util *lu, int argc, char **argv,
 
 			addattr16(n, 1024, IFLA_BR_VLAN_DEFAULT_PVID,
 				  default_pvid);
+		} else if (matches(*argv, "mcast_router") == 0) {
+			__u8 mcast_router;
+
+			NEXT_ARG();
+			if (get_u8(&mcast_router, *argv, 0))
+				invarg("invalid mcast_router", *argv);
+
+			addattr8(n, 1024, IFLA_BR_MCAST_ROUTER, mcast_router);
 		} else if (matches(*argv, "help") == 0) {
 			explain();
 			return -1;
@@ -277,6 +286,10 @@ static void bridge_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
 				    RTA_PAYLOAD(tb[IFLA_BR_GROUP_ADDR]),
 				    1 /*ARPHDR_ETHER*/, mac, sizeof(mac)));
 	}
+
+	if (tb[IFLA_BR_MCAST_ROUTER])
+		fprintf(f, "mcast_router %u ",
+			rta_getattr_u8(tb[IFLA_BR_MCAST_ROUTER]));
 }
 
 static void bridge_print_help(struct link_util *lu, int argc, char **argv,