- DHCP: normalize leases on startup (prioritize static leases over dynamic)

dhcpd/db.go

@@ -36,6 +36,8 @@ func ipInRange(start, stop, ip net.IP) bool {
 func (s *Server) dbLoad() {
 	s.leases = nil
 	s.IPpool = make(map[[4]byte]net.HardwareAddr)
+	dynLeases := []*Lease{}
+	staticLeases := []*Lease{}
 
 	data, err := ioutil.ReadFile(s.conf.DBFilePath)
 	if err != nil {
@@ -69,11 +71,47 @@ func (s *Server) dbLoad() {
 			Expiry:   time.Unix(obj[i].Expiry, 0),
 		}
 
-		s.leases = append(s.leases, &lease)
+		if obj[i].Expiry == leaseExpireStatic {
+			staticLeases = append(staticLeases, &lease)
+		} else {
+			dynLeases = append(dynLeases, &lease)
+		}
+	}
 
+	s.leases = normalizeLeases(staticLeases, dynLeases)
+
+	for _, lease := range s.leases {
 		s.reserveIP(lease.IP, lease.HWAddr)
 	}
-	log.Info("DHCP: loaded %d leases from DB", numLeases)
+
+	log.Info("DHCP: loaded %d (%d) leases from DB", len(s.leases), numLeases)
+}
+
+// Skip duplicate leases
+// Static leases have a priority over dynamic leases
+func normalizeLeases(staticLeases, dynLeases []*Lease) []*Lease {
+	leases := []*Lease{}
+	index := map[string]int{}
+
+	for i, lease := range staticLeases {
+		_, ok := index[lease.HWAddr.String()]
+		if ok {
+			continue // skip the lease with the same HW address
+		}
+		index[lease.HWAddr.String()] = i
+		leases = append(leases, lease)
+	}
+
+	for i, lease := range dynLeases {
+		_, ok := index[lease.HWAddr.String()]
+		if ok {
+			continue // skip the lease with the same HW address
+		}
+		index[lease.HWAddr.String()] = i
+		leases = append(leases, lease)
+	}
+
+	return leases
 }
 
 // Store lease table in DB