dhcpsvc: finish leases methods

internal/dhcpsvc/dhcpsvc.go

@@ -14,7 +14,9 @@ import (
 // Interface is a DHCP service.
 //
 // TODO(e.burkov):  Separate HostByIP, MACByIP, IPByHost into a separate
-// interface.  This is also valid for Enabled method.
+// interface.  This is also applicable to Enabled method.
+//
+// TODO(e.burkov):  Reconsider the requirements for the leases validity.
 type Interface interface {
 	agh.ServiceWithConfig[*Config]
 
@@ -49,7 +51,7 @@ type Interface interface {
 	AddLease(l *Lease) (err error)
 
 	// UpdateStaticLease changes an existing DHCP lease.  It returns an error if
-	// there is no lease with such hardware addressor if new values are invalid
+	// there is no lease with such hardware address or if new values are invalid
 	// or already exist.
 	UpdateStaticLease(l *Lease) (err error)
 

internal/dhcpsvc/interface.go

@@ -38,3 +38,29 @@ func (iface *netInterface) insertLease(l *Lease) (err error) {
 
 	return nil
 }
+
+// updateLease changes an existing lease within iface.  It returns an error if
+// there is no lease with such hardware address.
+func (iface *netInterface) updateLease(l *Lease) (prev *Lease, err error) {
+	i, found := slices.BinarySearchFunc(iface.leases, l, compareLeaseMAC)
+	if !found {
+		return nil, fmt.Errorf("no lease for mac %s", l.HWAddr)
+	}
+
+	prev, iface.leases[i] = iface.leases[i], l
+
+	return prev, nil
+}
+
+// removeLease removes an existing lease from iface.  It returns an error if
+// there is no lease equal to l.
+func (iface *netInterface) removeLease(l *Lease) (err error) {
+	i, found := slices.BinarySearchFunc(iface.leases, l, compareLeaseMAC)
+	if !found {
+		return fmt.Errorf("no lease for mac %s", l.HWAddr)
+	}
+
+	iface.leases = slices.Delete(iface.leases, i, i+1)
+
+	return nil
+}

internal/dhcpsvc/server.go

@@ -193,19 +193,112 @@ func (srv *DHCPServer) AddLease(l *Lease) (err error) {
 		iface, ok = srv.interfaces6.find(addr)
 	}
 	if !ok {
-		return fmt.Errorf("no interface for IP address %s", addr)
+		return fmt.Errorf("no interface for ip %s", addr)
 	}
 
+	loweredHostname := strings.ToLower(l.Hostname)
+
 	srv.leasesMu.Lock()
 	defer srv.leasesMu.Unlock()
 
+	if _, ok = srv.leaseByIP[addr]; ok {
+		return fmt.Errorf("lease for ip %s already exists", addr)
+	} else if _, ok = srv.leaseByName[loweredHostname]; ok {
+		return fmt.Errorf("lease for hostname %s already exists", l.Hostname)
+	}
+
 	err = iface.insertLease(l)
 	if err != nil {
 		return err
 	}
 
-	srv.leaseByIP[l.IP] = l
-	srv.leaseByName[strings.ToLower(l.Hostname)] = l
+	srv.leaseByIP[addr] = l
+	srv.leaseByName[loweredHostname] = l
+
+	return nil
+}
+
+// UpdateStaticLease implements the [Interface] interface for *DHCPServer.
+//
+// TODO(e.burkov):  Support moving leases between interfaces.
+func (srv *DHCPServer) UpdateStaticLease(l *Lease) (err error) {
+	var ok bool
+	var iface *netInterface
+
+	addr := l.IP
+
+	if addr.Is4() {
+		iface, ok = srv.interfaces4.find(addr)
+	} else {
+		iface, ok = srv.interfaces6.find(addr)
+	}
+	if !ok {
+		return fmt.Errorf("no interface for ip %s", addr)
+	}
+
+	loweredHostname := strings.ToLower(l.Hostname)
+
+	srv.leasesMu.Lock()
+	defer srv.leasesMu.Unlock()
+
+	existing, ok := srv.leaseByIP[addr]
+	if ok && !slices.Equal(l.HWAddr, existing.HWAddr) {
+		return fmt.Errorf("lease for ip %s already exists", addr)
+	}
+
+	existing, ok = srv.leaseByName[loweredHostname]
+	if ok && !slices.Equal(l.HWAddr, existing.HWAddr) {
+		return fmt.Errorf("lease for hostname %s already exists", l.Hostname)
+	}
+
+	prev, err := iface.updateLease(l)
+	if err != nil {
+		return err
+	}
+
+	delete(srv.leaseByIP, prev.IP)
+	srv.leaseByIP[addr] = l
+
+	delete(srv.leaseByName, strings.ToLower(prev.Hostname))
+	srv.leaseByName[loweredHostname] = l
+
+	return nil
+}
+
+// RemoveLease implements the [Interface] interface for *DHCPServer.
+func (srv *DHCPServer) RemoveLease(l *Lease) (err error) {
+	var ok bool
+	var iface *netInterface
+
+	addr := l.IP
+
+	if addr.Is4() {
+		iface, ok = srv.interfaces4.find(addr)
+	} else {
+		iface, ok = srv.interfaces6.find(addr)
+	}
+	if !ok {
+		return fmt.Errorf("no interface for ip %s", addr)
+	}
+
+	loweredHostname := strings.ToLower(l.Hostname)
+
+	srv.leasesMu.Lock()
+	defer srv.leasesMu.Unlock()
+
+	if _, ok = srv.leaseByIP[addr]; !ok {
+		return fmt.Errorf("no lease for ip %s", addr)
+	} else if _, ok = srv.leaseByName[loweredHostname]; !ok {
+		return fmt.Errorf("no lease for hostname %s", l.Hostname)
+	}
+
+	err = iface.removeLease(l)
+	if err != nil {
+		return err
+	}
+
+	delete(srv.leaseByIP, addr)
+	delete(srv.leaseByName, loweredHostname)
 
 	return nil
 }