WIP

peer/hub_poller.go

@@ -21,6 +21,7 @@ type HubPoller struct {
 	vpnNet    netip.Prefix
 	hubURL    string
 	apiKey    string
+	statePath string // where the network state cache is persisted
 	addCh     chan<- HubPeer
 	removeCh  chan<- wgtypes.Key
 	known     map[wgtypes.Key]int64 // pubKey → last seen version
@@ -30,6 +31,7 @@ func NewHubPoller(
 	selfVPNIP netip.Addr,
 	vpnNet netip.Prefix,
 	hubURL, apiKey string,
+	statePath string,
 	addCh chan<- HubPeer,
 	removeCh chan<- wgtypes.Key,
 ) (*HubPoller, error) {
@@ -44,6 +46,7 @@ func NewHubPoller(
 		vpnNet:    vpnNet,
 		hubURL:    u.String(),
 		apiKey:    apiKey,
+		statePath: statePath,
 		addCh:     addCh,
 		removeCh:  removeCh,
 		known:     make(map[wgtypes.Key]int64),
@@ -51,6 +54,14 @@ func NewHubPoller(
 }
 
 func (hp *HubPoller) Run() {
+	// Prime from the on-disk cache before reaching the hub, so the peer
+	// configures WireGuard from its last known state even if the hub is down.
+	// known starts empty, so this emits every cached peer as an add and seeds
+	// the version map; the first real poll then emits only deltas.
+	if state, err := loadNetworkState(hp.statePath); err == nil {
+		hp.apply(state)
+	}
+
 	hp.poll()
 	for range time.Tick(hubPollInterval) {
 		hp.poll()
@@ -90,10 +101,19 @@ func (hp *HubPoller) poll() {
 		return
 	}
 
-	hp.apply(state)
+	// Persist only when the state actually changed, to avoid needless writes
+	// on every poll.
+	if hp.apply(state) {
+		if err := saveNetworkState(hp.statePath, state); err != nil {
+			log.Printf("[HubPoller] save state: %v", err)
+		}
+	}
 }
 
-func (hp *HubPoller) apply(state m.NetworkState) {
+// apply diffs state against the known versions, emitting add events for new or
+// changed peers and remove events for peers that disappeared. It returns true
+// if anything changed.
+func (hp *HubPoller) apply(state m.NetworkState) (changed bool) {
 	seen := make(map[wgtypes.Key]struct{}, len(hp.known))
 
 	netAddr := hp.vpnNet.Addr().As4()
@@ -122,14 +142,18 @@ func (hp *HubPoller) apply(state m.NetworkState) {
 		}
 		hp.known[pubKey] = p.Version
 		hp.addCh <- hubPeerFrom(pubKey, vpnIP, p)
+		changed = true
 	}
 
 	for key := range hp.known {
 		if _, ok := seen[key]; !ok {
 			delete(hp.known, key)
 			hp.removeCh <- key
+			changed = true
 		}
 	}
+
+	return changed
 }
 
 func hubPeerFrom(pubKey wgtypes.Key, vpnIP netip.Addr, p *m.Peer) HubPeer {