Node: Support for EVM watcher safe blocks (#1727)

* Node: Support for EVM watcher safe blocks

* Fix merge error

* Add check of publishSafeBlocks if not useFinalized

node/pkg/watchers/evm/connectors/common.go

@@ -18,6 +18,7 @@ type NewBlock struct {
 	Number        *big.Int
 	Hash          common.Hash
 	L1BlockNumber *big.Int // This is only populated on some chains (Arbitrum)
+	Safe          bool
 }
 
 // Connector exposes Wormhole-specific interactions with an EVM-based network

node/pkg/watchers/evm/connectors/poller.go

@@ -25,16 +25,21 @@ type BlockPollConnector struct {
 	Connector
 	Delay             time.Duration
 	useFinalized      bool
+	publishSafeBlocks bool
 	finalizer         PollFinalizer
 	blockFeed         ethEvent.Feed
 	errFeed           ethEvent.Feed
 }
 
-func NewBlockPollConnector(ctx context.Context, baseConnector Connector, finalizer PollFinalizer, delay time.Duration, useFinalized bool) (*BlockPollConnector, error) {
+func NewBlockPollConnector(ctx context.Context, baseConnector Connector, finalizer PollFinalizer, delay time.Duration, useFinalized bool, publishSafeBlocks bool) (*BlockPollConnector, error) {
+	if publishSafeBlocks && !useFinalized {
+		return nil, fmt.Errorf("publishSafeBlocks may only be enabled if useFinalized is enabled")
+	}
 	connector := &BlockPollConnector{
 		Connector:         baseConnector,
 		Delay:             delay,
 		useFinalized:      useFinalized,
+		publishSafeBlocks: publishSafeBlocks,
 		finalizer:         finalizer,
 	}
 	err := supervisor.Run(ctx, "blockPoller", connector.run)
@@ -47,11 +52,19 @@ func NewBlockPollConnector(ctx context.Context, baseConnector Connector, finaliz
 func (b *BlockPollConnector) run(ctx context.Context) error {
 	logger := supervisor.Logger(ctx).With(zap.String("eth_network", b.Connector.NetworkName()))
 
-	lastBlock, err := b.getBlock(ctx, logger, nil)
+	lastBlock, err := b.getBlock(ctx, logger, nil, false)
 	if err != nil {
 		return err
 	}
 
+	var lastSafeBlock *NewBlock
+	if b.publishSafeBlocks {
+		lastSafeBlock, err = b.getBlock(ctx, logger, nil, true)
+		if err != nil {
+			return err
+		}
+	}
+
 	timer := time.NewTimer(time.Millisecond) // Start immediately.
 	supervisor.Signal(ctx, supervisor.SignalHealthy)
 
@@ -62,17 +75,30 @@ func (b *BlockPollConnector) run(ctx context.Context) error {
 			return ctx.Err()
 		case <-timer.C:
 			for count := 0; count < 3; count++ {
-				lastBlock, err = b.pollBlocks(ctx, logger, lastBlock)
+				lastBlock, err = b.pollBlocks(ctx, logger, lastBlock, false)
 				if err == nil {
 					break
 				}
-				logger.Error("polling encountered an error", zap.Error(err))
+				logger.Error("polling of block encountered an error", zap.Error(err))
 
 				// Wait an interval before trying again. We stay in this loop so that we
 				// try up to three times before causing the watcher to restart.
 				time.Sleep(b.Delay)
 			}
 
+			if err == nil && b.publishSafeBlocks {
+				for count := 0; count < 3; count++ {
+					lastSafeBlock, err = b.pollBlocks(ctx, logger, lastSafeBlock, true)
+					if err == nil {
+						break
+					}
+					logger.Error("polling of safe block encountered an error", zap.Error(err))
+
+					// Same wait as above.
+					time.Sleep(b.Delay)
+				}
+			}
+
 			if err != nil {
 				b.errFeed.Send(fmt.Sprint("polling encountered an error: ", err))
 			}
@@ -81,7 +107,7 @@ func (b *BlockPollConnector) run(ctx context.Context) error {
 	}
 }
 
-func (b *BlockPollConnector) pollBlocks(ctx context.Context, logger *zap.Logger, lastBlock *NewBlock) (lastPublishedBlock *NewBlock, retErr error) {
+func (b *BlockPollConnector) pollBlocks(ctx context.Context, logger *zap.Logger, lastBlock *NewBlock, safe bool) (lastPublishedBlock *NewBlock, retErr error) {
 	// Some of the testnet providers (like the one we are using for Arbitrum) limit how many transactions we can do. When that happens, the call hangs.
 	// Use a timeout so that the call will fail and the runable will get restarted. This should not happen in mainnet, but if it does, we will need to
 	// investigate why the runable is dying and fix the underlying problem.
@@ -94,7 +120,7 @@ func (b *BlockPollConnector) pollBlocks(ctx context.Context, logger *zap.Logger,
 	// Fetch the latest block on the chain
 	// We could do this on every iteration such that if a new block is created while this function is being executed,
 	// it would automatically fetch new blocks but in order to reduce API load this will be done on the next iteration.
-	latestBlock, err := b.getBlock(timeout, logger, nil)
+	latestBlock, err := b.getBlock(timeout, logger, nil, safe)
 	if err != nil {
 		logger.Error("failed to look up latest block",
 			zap.Uint64("lastSeenBlock", lastBlock.Number.Uint64()), zap.Error(err))
@@ -108,7 +134,7 @@ func (b *BlockPollConnector) pollBlocks(ctx context.Context, logger *zap.Logger,
 
 		// Try to fetch the next block between lastBlock and latestBlock
 		nextBlockNumber := new(big.Int).Add(lastPublishedBlock.Number, big.NewInt(1))
-		block, err := b.getBlock(timeout, logger, nextBlockNumber)
+		block, err := b.getBlock(timeout, logger, nextBlockNumber, safe)
 		if err != nil {
 			logger.Error("failed to fetch next block",
 				zap.Uint64("block", nextBlockNumber.Uint64()), zap.Error(err))
@@ -164,17 +190,21 @@ func (b *BlockPollConnector) SubscribeForBlocks(ctx context.Context, sink chan<-
 	return sub, nil
 }
 
-func (b *BlockPollConnector) getBlock(ctx context.Context, logger *zap.Logger, number *big.Int) (*NewBlock, error) {
+func (b *BlockPollConnector) getBlock(ctx context.Context, logger *zap.Logger, number *big.Int, safe bool) (*NewBlock, error) {
-	return getBlock(ctx, logger, b.Connector, number, b.useFinalized)
+	return getBlock(ctx, logger, b.Connector, number, b.useFinalized, safe)
 }
 
 // getBlock is a free function that can be called from other connectors to get a single block.
-func getBlock(ctx context.Context, logger *zap.Logger, conn Connector, number *big.Int, useFinalized bool) (*NewBlock, error) {
+func getBlock(ctx context.Context, logger *zap.Logger, conn Connector, number *big.Int, useFinalized bool, safe bool) (*NewBlock, error) {
 	var numStr string
 	if number != nil {
 		numStr = ethHexUtils.EncodeBig(number)
 	} else if useFinalized {
+		if safe {
+			numStr = "safe"
+		} else {
 			numStr = "finalized"
+		}
 	} else {
 		numStr = "latest"
 	}
@@ -213,5 +243,6 @@ func getBlock(ctx context.Context, logger *zap.Logger, conn Connector, number *b
 		Number:        &n,
 		Hash:          m.Hash,
 		L1BlockNumber: l1bn,
+		Safe:          safe,
 	}, nil
 }

node/pkg/watchers/evm/connectors/polygon.go

@@ -147,7 +147,7 @@ func (c *PolygonConnector) postBlock(ctx context.Context, blockNum *big.Int, sin
 		return fmt.Errorf("blockNum is nil")
 	}
 
-	block, err := getBlock(ctx, c.logger, c.Connector, blockNum, false)
+	block, err := getBlock(ctx, c.logger, c.Connector, blockNum, false, false)
 	if err != nil {
 		return fmt.Errorf("failed to get block %s: %w", blockNum.String(), err)
 	}

node/pkg/watchers/evm/watcher.go

@@ -186,6 +186,8 @@ func (w *Watcher) Run(ctx context.Context) error {
 	timeout, cancel := context.WithTimeout(ctx, 15*time.Second)
 	defer cancel()
 
+	safeBlocksSupported := false
+
 	var err error
 	if w.chainID == vaa.ChainIDCelo && !w.unsafeDevMode {
 		// When we are running in mainnet or testnet, we need to use the Celo ethereum library rather than go-ethereum.
@@ -197,14 +199,20 @@ func (w *Watcher) Run(ctx context.Context) error {
 			return fmt.Errorf("dialing eth client failed: %w", err)
 		}
 	} else if useFinalizedBlocks {
+		if w.chainID == vaa.ChainIDEthereum && !w.unsafeDevMode {
+			safeBlocksSupported = true
+			logger.Info("using finalized blocks, will publish safe blocks")
+		} else {
 			logger.Info("using finalized blocks")
+		}
+
 		baseConnector, err := connectors.NewEthereumConnector(timeout, w.networkName, w.url, w.contract, logger)
 		if err != nil {
 			ethConnectionErrors.WithLabelValues(w.networkName, "dial_error").Inc()
 			p2p.DefaultRegistry.AddErrorCount(w.chainID, 1)
 			return fmt.Errorf("dialing eth client failed: %w", err)
 		}
-		w.ethConn, err = connectors.NewBlockPollConnector(ctx, baseConnector, finalizers.NewDefaultFinalizer(), 250*time.Millisecond, true)
+		w.ethConn, err = connectors.NewBlockPollConnector(ctx, baseConnector, finalizers.NewDefaultFinalizer(), 250*time.Millisecond, true, safeBlocksSupported)
 		if err != nil {
 			ethConnectionErrors.WithLabelValues(w.networkName, "dial_error").Inc()
 			p2p.DefaultRegistry.AddErrorCount(w.chainID, 1)
@@ -218,7 +226,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 			return fmt.Errorf("dialing eth client failed: %w", err)
 		}
 		finalizer := finalizers.NewMoonbeamFinalizer(logger, baseConnector)
-		w.ethConn, err = connectors.NewBlockPollConnector(ctx, baseConnector, finalizer, 250*time.Millisecond, false)
+		w.ethConn, err = connectors.NewBlockPollConnector(ctx, baseConnector, finalizer, 250*time.Millisecond, false, false)
 		if err != nil {
 			ethConnectionErrors.WithLabelValues(w.networkName, "dial_error").Inc()
 			p2p.DefaultRegistry.AddErrorCount(w.chainID, 1)
@@ -235,7 +243,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 			return fmt.Errorf("dialing eth client failed: %w", err)
 		}
 		finalizer := finalizers.NewNeonFinalizer(logger, baseConnector, baseConnector.Client(), w.l1Finalizer)
-		pollConnector, err := connectors.NewBlockPollConnector(ctx, baseConnector, finalizer, 250*time.Millisecond, false)
+		pollConnector, err := connectors.NewBlockPollConnector(ctx, baseConnector, finalizer, 250*time.Millisecond, false, false)
 		if err != nil {
 			ethConnectionErrors.WithLabelValues(w.networkName, "dial_error").Inc()
 			p2p.DefaultRegistry.AddErrorCount(w.chainID, 1)
@@ -258,7 +266,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 			return fmt.Errorf("dialing eth client failed: %w", err)
 		}
 		finalizer := finalizers.NewArbitrumFinalizer(logger, baseConnector, baseConnector.Client(), w.l1Finalizer)
-		pollConnector, err := connectors.NewBlockPollConnector(ctx, baseConnector, finalizer, 250*time.Millisecond, false)
+		pollConnector, err := connectors.NewBlockPollConnector(ctx, baseConnector, finalizer, 250*time.Millisecond, false, false)
 		if err != nil {
 			ethConnectionErrors.WithLabelValues(w.networkName, "dial_error").Inc()
 			p2p.DefaultRegistry.AddErrorCount(w.chainID, 1)
@@ -281,7 +289,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 			return fmt.Errorf("dialing eth client failed: %w", err)
 		}
 		finalizer := finalizers.NewOptimismFinalizer(timeout, logger, baseConnector, w.l1Finalizer)
-		w.ethConn, err = connectors.NewBlockPollConnector(ctx, baseConnector, finalizer, 250*time.Millisecond, false)
+		w.ethConn, err = connectors.NewBlockPollConnector(ctx, baseConnector, finalizer, 250*time.Millisecond, false, false)
 		if err != nil {
 			ethConnectionErrors.WithLabelValues(w.networkName, "dial_error").Inc()
 			p2p.DefaultRegistry.AddErrorCount(w.chainID, 1)
@@ -348,9 +356,10 @@ func (w *Watcher) Run(ctx context.Context) error {
 		}
 	}()
 
-	// Track the current block number so we can compare it to the block number of
+	// Track the current block numbers so we can compare it to the block number of
 	// the message publication for observation requests.
 	var currentBlockNumber uint64
+	var currentSafeBlockNumber uint64
 
 	go func() {
 		for {
@@ -377,11 +386,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 				// always sends the head before it sends the logs (implicit synchronization
 				// by relying on the same websocket connection).
 				blockNumberU := atomic.LoadUint64(&currentBlockNumber)
-				if blockNumberU == 0 {
+				safeBlockNumberU := atomic.LoadUint64(&currentSafeBlockNumber)
-					logger.Error("no block number available, ignoring observation request",
-						zap.String("eth_network", w.networkName))
-					continue
-				}
 
 				timeout, cancel := context.WithTimeout(ctx, 5*time.Second)
 				blockNumber, msgs, err := MessageEventsForTransaction(timeout, w.ethConn, w.contract, w.chainID, tx)
@@ -407,6 +412,43 @@ func (w *Watcher) Run(ctx context.Context) error {
 						continue
 					}
 
+					if msg.ConsistencyLevel == vaa.ConsistencyLevelSafe && safeBlocksSupported {
+						if safeBlockNumberU == 0 {
+							logger.Error("no safe block number available, ignoring observation request",
+								zap.String("eth_network", w.networkName))
+							continue
+						}
+
+						if blockNumber <= safeBlockNumberU {
+							logger.Info("re-observed message publication transaction",
+								zap.Stringer("tx", msg.TxHash),
+								zap.Stringer("emitter_address", msg.EmitterAddress),
+								zap.Uint64("sequence", msg.Sequence),
+								zap.Uint64("current_safe_block", safeBlockNumberU),
+								zap.Uint64("observed_block", blockNumber),
+								zap.String("eth_network", w.networkName),
+							)
+							w.msgChan <- msg
+						} else {
+							logger.Info("ignoring re-observed message publication transaction",
+								zap.Stringer("tx", msg.TxHash),
+								zap.Stringer("emitter_address", msg.EmitterAddress),
+								zap.Uint64("sequence", msg.Sequence),
+								zap.Uint64("current_safe_block", safeBlockNumberU),
+								zap.Uint64("observed_block", blockNumber),
+								zap.String("eth_network", w.networkName),
+							)
+						}
+
+						continue
+					}
+
+					if blockNumberU == 0 {
+						logger.Error("no block number available, ignoring observation request",
+							zap.String("eth_network", w.networkName))
+						continue
+					}
+
 					var expectedConfirmations uint64
 					if w.waitForConfirmations {
 						expectedConfirmations = uint64(msg.ConsistencyLevel)
@@ -554,7 +596,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 					continue
 				}
 				if ev.Number == nil {
-					logger.Error("new header block number is nil", zap.String("eth_network", w.networkName))
+					logger.Error("new header block number is nil", zap.String("eth_network", w.networkName), zap.Bool("is_safe_block", ev.Safe))
 					continue
 				}
 
@@ -563,6 +605,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 				logger.Info("processing new header",
 					zap.Stringer("current_block", ev.Number),
 					zap.Stringer("current_blockhash", currentHash),
+					zap.Bool("is_safe_block", ev.Safe),
 					zap.String("eth_network", w.networkName))
 				currentEthHeight.WithLabelValues(w.networkName).Set(float64(ev.Number.Int64()))
 				readiness.SetReady(w.readiness)
@@ -574,12 +617,24 @@ func (w *Watcher) Run(ctx context.Context) error {
 				w.pendingMu.Lock()
 
 				blockNumberU := ev.Number.Uint64()
+				if ev.Safe {
+					atomic.StoreUint64(&currentSafeBlockNumber, blockNumberU)
+				} else {
 					atomic.StoreUint64(&currentBlockNumber, blockNumberU)
 					atomic.StoreUint64(&w.latestFinalizedBlockNumber, blockNumberU)
+				}
 
 				for key, pLock := range w.pending {
+					// If this block is safe, only process messages wanting safe.
+					// If it's not safe, only process messages wanting finalized.
+					if safeBlocksSupported {
+						if ev.Safe != (pLock.message.ConsistencyLevel == vaa.ConsistencyLevelSafe) {
+							continue
+						}
+					}
+
 					var expectedConfirmations uint64
-					if w.waitForConfirmations {
+					if w.waitForConfirmations && !ev.Safe {
 						expectedConfirmations = uint64(pLock.message.ConsistencyLevel)
 					}
 
@@ -591,6 +646,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 							zap.Stringer("emitter_address", key.EmitterAddress),
 							zap.Uint64("sequence", key.Sequence),
 							zap.Stringer("current_block", ev.Number),
+							zap.Bool("is_safe_block", ev.Safe),
 							zap.Stringer("current_blockhash", currentHash),
 							zap.String("eth_network", w.networkName),
 							zap.Uint64("expectedConfirmations", expectedConfirmations),
@@ -622,6 +678,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 								zap.Stringer("emitter_address", key.EmitterAddress),
 								zap.Uint64("sequence", key.Sequence),
 								zap.Stringer("current_block", ev.Number),
+								zap.Bool("is_safe_block", ev.Safe),
 								zap.Stringer("current_blockhash", currentHash),
 								zap.String("eth_network", w.networkName),
 								zap.Error(err))
@@ -640,6 +697,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 								zap.Stringer("emitter_address", key.EmitterAddress),
 								zap.Uint64("sequence", key.Sequence),
 								zap.Stringer("current_block", ev.Number),
+								zap.Bool("is_safe_block", ev.Safe),
 								zap.Stringer("current_blockhash", currentHash),
 								zap.String("eth_network", w.networkName),
 								zap.Error(err))
@@ -656,6 +714,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 								zap.Stringer("emitter_address", key.EmitterAddress),
 								zap.Uint64("sequence", key.Sequence),
 								zap.Stringer("current_block", ev.Number),
+								zap.Bool("is_safe_block", ev.Safe),
 								zap.Stringer("current_blockhash", currentHash),
 								zap.String("eth_network", w.networkName),
 								zap.Error(err))
@@ -672,6 +731,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 								zap.Stringer("emitter_address", key.EmitterAddress),
 								zap.Uint64("sequence", key.Sequence),
 								zap.Stringer("current_block", ev.Number),
+								zap.Bool("is_safe_block", ev.Safe),
 								zap.Stringer("current_blockhash", currentHash),
 								zap.String("eth_network", w.networkName))
 							delete(w.pending, key)
@@ -685,6 +745,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 							zap.Stringer("emitter_address", key.EmitterAddress),
 							zap.Uint64("sequence", key.Sequence),
 							zap.Stringer("current_block", ev.Number),
+							zap.Bool("is_safe_block", ev.Safe),
 							zap.Stringer("current_blockhash", currentHash),
 							zap.String("eth_network", w.networkName))
 						delete(w.pending, key)
@@ -696,6 +757,7 @@ func (w *Watcher) Run(ctx context.Context) error {
 				w.pendingMu.Unlock()
 				logger.Info("processed new header",
 					zap.Stringer("current_block", ev.Number),
+					zap.Bool("is_safe_block", ev.Safe),
 					zap.Stringer("current_blockhash", currentHash),
 					zap.Duration("took", time.Since(start)),
 					zap.String("eth_network", w.networkName))

sdk/vaa/structs.go

@@ -116,6 +116,7 @@ type (
 
 const (
 	ConsistencyLevelPublishImmediately = uint8(200)
+	ConsistencyLevelSafe               = uint8(201)
 )
 
 func (a Address) MarshalJSON() ([]byte, error) {