deal with TODOs:

1. implement is_owner() method.
2. add skew time to VrrpInstance state
3. Implement send advert with priority 0
    when shutdown functionality is being carried out

holo-vrrp/src/instance.rs

@@ -192,9 +192,22 @@ impl Instance {
     }
 
     pub(crate) fn shutdown(&mut self, interface: &InterfaceView) {
-        if self.state.state == fsm::State::Master {
+        if self.state.state == fsm::State::Master
+            && let Some(src_ip) = interface.system.addresses.first()
+            && let Some(net) = &self.net
+        {
             // Send an advertisement with Priority = 0.
-            // TODO
+            let mut pkt = self.generate_vrrp_packet();
+            pkt.priority = 0;
+            pkt.generate_checksum();
+
+            let packet = VrrpPacket {
+                ip: self.generate_ipv4_packet(src_ip.ip()),
+                vrrp: pkt,
+            };
+
+            let msg = NetTxPacketMsg::Vrrp { packet };
+            let _ = net.net_tx_packetp.send(msg);
         }
 
         // Transition to the Initialize state.
@@ -410,6 +423,16 @@ impl Instance {
             let _ = net.net_tx_packetp.send(msg);
         }
     }
+
+    pub(crate) fn is_owner(&self, interface_sys: &InterfaceSys) -> bool {
+        let iter = self.config.virtual_addresses.iter();
+        for addr in iter {
+            if interface_sys.addresses.contains(addr) {
+                return true;
+            }
+        }
+        false
+    }
 }
 
 impl Drop for Instance {

holo-vrrp/src/northbound/state.rs

@@ -40,19 +40,17 @@ fn load_callbacks() -> Callbacks<Interface> {
             let iter = interface.instances.iter().map(|(vrid, instance)| ListEntry::Instance(*vrid, instance));
             Some(Box::new(iter))
         })
-        .get_object(|_interface, args| {
+        .get_object(|interface, args| {
             use interfaces::interface::ipv4::vrrp::vrrp_instance::VrrpInstance;
             let (vrid, instance) = args.list_entry.as_instance().unwrap();
             Box::new(VrrpInstance {
                 vrid: *vrid,
                 state: Some(instance.state.state.to_yang()),
-                // TODO
-                is_owner: None,
+                is_owner: Some(instance.is_owner(&interface.system)),
                 last_adv_source: instance.state.last_adv_src.map(std::convert::Into::into).map(Cow::Owned).ignore_in_testing(),
                 up_datetime: instance.state.up_time.as_ref().map(Cow::Borrowed).ignore_in_testing(),
                 master_down_interval: instance.state.timer.as_master_down_timer().map(|task| task.remaining().as_millis() as u32 / 10).ignore_in_testing(),
-                // TODO
-                skew_time: None,
+                skew_time: Some(instance.config.skew_time() as u32),
                 last_event: Some(instance.state.last_event.to_yang()).ignore_in_testing(),
                 new_master_reason: Some(instance.state.new_master_reason.to_yang()),
             })
@@ -81,7 +79,8 @@ fn load_callbacks() -> Callbacks<Interface> {
 
 impl Provider for Interface {
     // TODO
-    const STATE_PATH: &'static str = "";
+    const STATE_PATH: &'static str =
+        "/ietf-interfaces:interfaces/interface[type=holo-vrrp:vrrp][name='main']/ietf-vrrp:vrrp";
 
     type ListEntry<'a> = ListEntry<'a>;