Skip dBFT extensible verification during first node sync

consensus/dbft/dbft.go

@@ -185,7 +185,9 @@ type DBFT struct {
 	// downloader events. Downloader events are used to track miner's state since
 	// miner work may be temporary suspended due to the node sync.
 	mux *event.TypeMux
-	// syncing indicates whether the node is still syncing.
+	// syncing indicates whether the node is still syncing. This variable is updated
+	// irrespectively from the engine activity, and thus, may be relied on even when
+	// dBFT engine is not started.
 	syncing atomic.Bool
 
 	config *params.DBFTConfig // Consensus engine configuration parameters
@@ -712,6 +714,47 @@ func (c *DBFT) WithRequestTxs(f func(hashed []common.Hash)) {
 // the ongoing node sync process.
 func (c *DBFT) WithMux(mux *event.TypeMux) {
 	c.mux = mux
+
+	go c.syncWatcher()
+}
+
+// syncWatcher is a standalone loop aimed to be active irrespectively of dBFT engine
+// activity. It tracks the first chain sync attempt till its end.
+func (c *DBFT) syncWatcher() {
+	downloaderEvents := c.mux.Subscribe(downloader.StartEvent{}, downloader.DoneEvent{}, downloader.FailedEvent{})
+	defer func() {
+		if !downloaderEvents.Closed() {
+			downloaderEvents.Unsubscribe()
+		}
+	}()
+	dlEventCh := downloaderEvents.Chan()
+
+events:
+	for {
+		select {
+		case <-c.quit:
+			break events
+		case ev := <-dlEventCh:
+			if ev == nil {
+				// Unsubscription done, stop listening.
+				dlEventCh = nil
+				break events
+			}
+			switch ev.Data.(type) {
+			case downloader.StartEvent:
+				c.syncing.Store(true)
+
+			case downloader.FailedEvent:
+				c.syncing.Store(false)
+
+			case downloader.DoneEvent:
+				c.syncing.Store(false)
+
+				// Stop reacting to downloader events.
+				downloaderEvents.Unsubscribe()
+			}
+		}
+	}
 }
 
 // WithTxPool initializes transaction pool API for DBFT interactions with memory pool
@@ -1244,7 +1287,7 @@ func (c *DBFT) eventLoop() {
 	// been broadcasted the events are unregistered and the loop is exited. This to
 	// prevent a major security vuln where external parties can DOS you with blocks
 	// and halt your dBFT operation for as long as the DOS continues.
-	downloaderEvents := c.mux.Subscribe(downloader.StartEvent{}, downloader.DoneEvent{}, downloader.FailedEvent{})
+	downloaderEvents := c.mux.Subscribe(downloader.DoneEvent{}, downloader.FailedEvent{})
 	defer func() {
 		if !downloaderEvents.Closed() {
 			downloaderEvents.Unsubscribe()
@@ -1296,7 +1339,7 @@ events:
 		case tx := <-c.txs:
 			c.dbft.OnTransaction(&Transaction{Tx: tx})
 		case b := <-c.chainHeadEvents:
-			err := c.handleChainBlock(b.Block.Header())
+			err := c.handleChainBlock(b.Block.Header(), true)
 			if err != nil {
 				log.Warn("Failed to handle chain block",
 					"index", b.Block.NumberU64(),
@@ -1318,14 +1361,9 @@ events:
 				continue
 			}
 			switch ev.Data.(type) {
-			case downloader.StartEvent:
-				c.syncing.Store(true)
-
 			case downloader.FailedEvent:
-				c.syncing.Store(false)
-
 				latest := c.chain.CurrentHeader()
-				err := c.handleChainBlock(latest)
+				err := c.handleChainBlock(latest, false)
 				if err != nil {
 					log.Warn("Failed to handle latest chain block",
 						"index", latest.Number.Uint64(),
@@ -1334,13 +1372,11 @@ events:
 				}
 
 			case downloader.DoneEvent:
-				c.syncing.Store(false)
-
 				// Stop reacting to downloader events.
 				downloaderEvents.Unsubscribe()
 
 				latest := c.chain.CurrentHeader()
-				err := c.handleChainBlock(latest)
+				err := c.handleChainBlock(latest, false)
 				if err != nil {
 					log.Warn("Failed to handle latest chain block",
 						"index", latest.Number.Uint64(),
@@ -1361,7 +1397,7 @@ events:
 			}
 		}
 		if latestBlock.Block != nil {
-			err := c.handleChainBlock(latestBlock.Block.Header())
+			err := c.handleChainBlock(latestBlock.Block.Header(), true)
 			if err != nil {
 				log.Warn("Failed to handle latest chain block",
 					"index", latestBlock.Block.NumberU64(),
@@ -1410,6 +1446,10 @@ func (c *DBFT) OnPayload(cp *dbftproto.Message) error {
 		log.Debug("Skip dBFT payload handling: dbft is inactive or not started yet", "hash", cp.Hash())
 		return nil
 	}
+	if c.syncing.Load() {
+		log.Debug("Skip dBFT payload handling due to sync", "hash", cp.Hash())
+		return nil
+	}
 
 	p := payloadFromMessage(cp)
 	// decode payload data into message
@@ -1477,15 +1517,21 @@ func (c *DBFT) validatePayload(p *Payload) error {
 
 // IsExtensibleAllowed determines if address is allowed to send extensible payloads
 // (only consensus payloads for now) at the specified height.
-func (c *DBFT) IsExtensibleAllowed(h uint64, u common.Address) bool {
+func (c *DBFT) IsExtensibleAllowed(h uint64, u common.Address) error {
+	// Can't verify extensible sender if the node has an outdated state.
+	if c.syncing.Load() {
+		return dbftproto.ErrSyncing
+	}
 	// Only validators are included into extensible whitelist for now.
 	validators, err := c.getValidators(&h, nil, nil)
 	if err != nil {
-		return false
+		return fmt.Errorf("failed to get validators: %w", err)
 	}
 	n := sort.Search(len(validators), func(i int) bool { return validators[i].Cmp(u) >= 0 })
-	res := n < len(validators)
-	return res
+	if n >= len(validators) {
+		return fmt.Errorf("address is not a validator")
+	}
+	return nil
 }
 
 func (c *DBFT) newPayload(ctx *dbft.Context[common.Hash], t dbft.MessageType, msg any) dbft.ConsensusPayload[common.Hash] {
@@ -1503,11 +1549,11 @@ func (c *DBFT) newPayload(ctx *dbft.Context[common.Hash], t dbft.MessageType, ms
 	return cp
 }
 
-func (c *DBFT) handleChainBlock(h *types.Header) error {
+func (c *DBFT) handleChainBlock(h *types.Header, checkForSync bool) error {
 	// A short path if miner is not active and the node is in the process of block
 	// sync. In this case dBFT can't react properly on the newcoming blocks since no
 	// sealing task is expected from miner.
-	if c.syncing.Load() {
+	if checkForSync && c.syncing.Load() {
 		log.Info("Skipping dBFT block callback due to sync",
 			"block index", h.Number.Int64(),
 			"dbft index", c.dbft.BlockIndex,

eth/backend.go

@@ -276,7 +276,7 @@ func New(stack *node.Node, config *ethconfig.Config) (*Ethereum, error) {
 	var (
 		bft                 *dbft.DBFT
 		onPayload           func(*dbftproto.Message) error
-		isExtensibleAllowed func(uint64, common.Address) bool
+		isExtensibleAllowed func(uint64, common.Address) error
 	)
 	switch t := eth.engine.(type) {
 	case *dbft.DBFT:

eth/protocols/dbft/handler.go

@@ -34,6 +34,10 @@ const (
 	maxMessageSize = 4 * 1024 * 1024
 )
 
+// ErrSyncing is returned when operation can't be performed due to the fact that
+// the node is in the process of chain sync.
+var ErrSyncing = errors.New("node is syncing")
+
 var (
 	errMsgTooLarge    = errors.New("message too long")
 	errDecode         = errors.New("invalid message")

eth/protocols/dbft/ledger.go

@@ -10,10 +10,10 @@ import (
 
 type ledger struct {
 	bc                  BlockChainAPI
-	isExtensibleAllowed func(height uint64, addr common.Address) bool
+	isExtensibleAllowed func(height uint64, addr common.Address) error
 }
 
-func newLedger(bc BlockChainAPI, isExtensibleAllowed func(uint64, common.Address) bool) *ledger {
+func newLedger(bc BlockChainAPI, isExtensibleAllowed func(uint64, common.Address) error) *ledger {
 	return &ledger{
 		bc:                  bc,
 		isExtensibleAllowed: isExtensibleAllowed,
@@ -24,6 +24,6 @@ func (l *ledger) BlockHeight() uint64 {
 	return uint64(l.bc.BlockNumber())
 }
 
-func (l *ledger) IsAddressAllowed(addr common.Address) bool {
+func (l *ledger) IsAddressAllowed(addr common.Address) error {
 	return l.isExtensibleAllowed(l.BlockHeight(), addr)
 }

eth/protocols/dbft/pool.go

@@ -14,7 +14,7 @@ import (
 // Ledger is enough of Blockchain to satisfy Pool.
 type Ledger interface {
 	BlockHeight() uint64
-	IsAddressAllowed(common.Address) bool
+	IsAddressAllowed(common.Address) error
 }
 
 // Pool represents a pool of extensible payloads.
@@ -90,8 +90,13 @@ func (p *Pool) verify(m *Message) (bool, error) {
 		}
 		return false, errInvalidHeight
 	}
-	if !p.chain.IsAddressAllowed(m.Sender) {
-		return false, errDisallowedSender
+	err = p.chain.IsAddressAllowed(m.Sender)
+	if err != nil {
+		// There's no reliable way to check sender for syncing node.
+		if errors.Is(err, ErrSyncing) {
+			return false, nil
+		}
+		return false, err
 	}
 	return true, nil
 }
@@ -120,7 +125,7 @@ func (p *Pool) RemoveStale(index uint64) {
 			old := elem
 			elem = elem.Next()
 
-			if m.ValidBlockEnd <= index || !p.chain.IsAddressAllowed(m.Sender) {
+			if m.ValidBlockEnd <= index || p.chain.IsAddressAllowed(m.Sender) != nil {
 				delete(p.verified, h)
 				lst.Remove(old)
 				continue

eth/protocols/dbft/service.go

@@ -36,7 +36,7 @@ type Service struct {
 }
 
 // New creates a new instance of [Service].
-func New(bc BlockChainAPI, onPayload func(*Message) error, isExtensibleAllowed func(uint64, common.Address) bool) *Service {
+func New(bc BlockChainAPI, onPayload func(*Message) error, isExtensibleAllowed func(uint64, common.Address) error) *Service {
 	poolLedger := newLedger(bc, isExtensibleAllowed)
 	return &Service{
 		bc:        bc,