Fix gossip validation not detecting UUID mismatch on success

dht.go

@@ -51,6 +51,12 @@ type DHT struct {
 	pendingRequests map[string]chan *DHTMessage
 	pendingMu       sync.RWMutex
 
+	// Inbound connection tracking (for outbound-only detection)
+	startTime           time.Time
+	hasReceivedInbound  bool
+	inboundMu           sync.RWMutex
+	lastInboundWarning  time.Time
+
 	// Shutdown coordination
 	shutdown chan struct{}
 	wg       sync.WaitGroup
@@ -64,6 +70,7 @@ func NewDHT(localSystem *System, storage *Storage, listenAddr string) *DHT {
 		listenAddr:      listenAddr,
 		pendingRequests: make(map[string]chan *DHTMessage),
 		shutdown:        make(chan struct{}),
+		startTime:       time.Now(),
 		httpClient: &http.Client{
 			Timeout: RequestTimeout,
 		},
@@ -106,6 +113,43 @@ func (dht *DHT) Stop() {
 	log.Printf("DHT stopped")
 }
 
+// markInboundReceived records that we've received an inbound connection
+func (dht *DHT) markInboundReceived() {
+	dht.inboundMu.Lock()
+	dht.hasReceivedInbound = true
+	dht.inboundMu.Unlock()
+}
+
+// checkInboundStatus logs a warning if no inbound connections after startup period
+func (dht *DHT) checkInboundStatus() {
+	dht.inboundMu.RLock()
+	hasInbound := dht.hasReceivedInbound
+	lastWarning := dht.lastInboundWarning
+	dht.inboundMu.RUnlock()
+
+	if hasInbound {
+		return
+	}
+
+	// Only warn after 10 minutes of uptime
+	if time.Since(dht.startTime) < 10*time.Minute {
+		return
+	}
+
+	// Repeat warning every 6 hours
+	if !lastWarning.IsZero() && time.Since(lastWarning) < 6*time.Hour {
+		return
+	}
+
+	dht.inboundMu.Lock()
+	dht.lastInboundWarning = time.Now()
+	dht.inboundMu.Unlock()
+
+	log.Printf("WARNING: No inbound connections received after 10 minutes.")
+	log.Printf("  Your node may be in outbound-only mode (can see network but others can't reach you).")
+	log.Printf("  Check that port %s is open and forwarded correctly, as UPnP may have failed.", dht.listenAddr)
+}
+
 // updateRoutingTable adds a node to the peer cache
 // Simplified from Kademlia - we just cache all peers we hear about
 func (dht *DHT) updateRoutingTable(sys *System) {
@@ -218,6 +262,9 @@ func (dht *DHT) handleDHTMessage(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Mark that we've received an inbound request (not a response)
+	dht.markInboundReceived()
+
 	switch msg.Type {
 	case MessageTypePing:
 		response, err = dht.handlePing(&msg)

dht_maintenance.go

@@ -54,6 +54,7 @@ func (dht *DHT) peerLivenessLoop() {
 			return
 		case <-ticker.C:
 			dht.checkPeerLiveness()
+			dht.checkInboundStatus()
 		}
 	}
 }
@@ -208,7 +209,7 @@ func (dht *DHT) validateGossipSystems() {
 		}
 
 		// Try to ping the system directly
-		_, err := dht.Ping(sys.PeerAddress)
+		respSystem, err := dht.Ping(sys.PeerAddress)
 		if err != nil {
 			// Failed to contact - check if this is the expected system
 			// The Ping function already handles UUID mismatches
@@ -223,6 +224,16 @@ func (dht *DHT) validateGossipSystems() {
 				dht.routingTable.RemoveFromCache(sys.ID)
 				removed++
 			}
+		} else if respSystem != nil && respSystem.ID != sys.ID {
+			// UUID mismatch - a different system now lives at this address
+			// The gossip entry is stale, remove it
+			log.Printf("  %s (%s): UUID mismatch - address now belongs to %s (%s), removing stale entry",
+				sys.Name, sys.ID.String()[:8], respSystem.Name, respSystem.ID.String()[:8])
+			dht.routingTable.RemoveFromCache(sys.ID)
+			if err := dht.storage.DeletePeerSystem(sys.ID); err != nil {
+				log.Printf("Warning: failed to delete stale peer system %s: %v", sys.ID.String()[:8], err)
+			}
+			removed++
 		} else {
 			verified++
 			log.Printf("  %s: verified", sys.Name)