Drop hostQueries to our overlay addresses (#1866)

* Drop hostQueries to our overlay addresses

Don't bother responding to hostQuery's for our overlay addresses.

lighthouse.go

@@ -34,7 +34,9 @@ type LightHouse struct {
 
 	myVpnNetworks      []netip.Prefix
 	myVpnNetworksTable *bart.Lite
-	punchy             *Punchy
+	// myVpnAddrsTable contains our overlay host addrs, as opposed to the overlay networks
+	myVpnAddrsTable *bart.Lite
+	punchy          *Punchy
 
 	// localAddrsFn enumerates the underlay addresses we advertise. It is a field so tests can supply simulated
 	// addresses rather than whatever this machine's NICs happen to be. Set it before Start.
@@ -104,6 +106,7 @@ func NewLightHouseFromConfig(ctx context.Context, l *slog.Logger, c *config.C, c
 		amLighthouse:       amLighthouse,
 		myVpnNetworks:      cs.myVpnNetworks,
 		myVpnNetworksTable: cs.myVpnNetworksTable,
+		myVpnAddrsTable:    cs.myVpnAddrsTable,
 		addrMap:            make(map[netip.Addr]*RemoteList),
 		nebulaPort:         nebulaPort,
 		punchy:             p,
@@ -1158,6 +1161,17 @@ func (lhh *LightHouseHandler) handleHostQuery(n *NebulaMeta, fromVpnAddrs []neti
 		return
 	}
 
+	// Don't respond to requests for us.
+	if lhh.lh.myVpnAddrsTable.Contains(queryVpnAddr) {
+		if lhh.l.Enabled(context.Background(), slog.LevelDebug) {
+			lhh.l.Debug("Ignoring HostQuery for one of my own addresses",
+				"fromVpnAddrs", fromVpnAddrs,
+				"queryVpnAddr", queryVpnAddr,
+			)
+		}
+		return
+	}
+
 	found, ln, err := lhh.lh.queryAndPrepMessage(queryVpnAddr, func(c *cache) (int, error) {
 		n = lhh.resetMeta()
 		n.Type = NebulaMeta_HostQueryReply