node: arbitrum watcher fix (#1699)

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

@@ -0,0 +1,42 @@
+// On Arbitrum we are unable to get blocks by transaction hash using the go-ethereum library
+// because it fails with "transaction type not supported". However, calling the underlying
+// eth_getBlockByHash directly works. The sole function of this connector is to implement
+// TimeOfBlockByHash using the raw connection.
+
+package connectors
+
+import (
+	"context"
+	"fmt"
+	"strconv"
+
+	ethCommon "github.com/ethereum/go-ethereum/common"
+)
+
+type ArbitrumConnector struct {
+	Connector
+}
+
+func NewArbitrumConnector(ctx context.Context, baseConnector Connector) (*ArbitrumConnector, error) {
+	connector := &ArbitrumConnector{Connector: baseConnector}
+	return connector, nil
+}
+
+func (a *ArbitrumConnector) TimeOfBlockByHash(ctx context.Context, hash ethCommon.Hash) (uint64, error) {
+	type Marshaller struct {
+		Time string `json:"timestamp"        gencodec:"required"`
+	}
+
+	var m *Marshaller
+	err := a.RawCallContext(ctx, &m, "eth_getBlockByHash", hash, false)
+	if err != nil {
+		return 0, fmt.Errorf("failed to get block %s: %w", hash.String(), err)
+	}
+
+	num, err := strconv.ParseUint(m.Time[2:], 16, 64)
+	if err != nil {
+		return 0, fmt.Errorf("failed to parse time %s: %w", m.Time, err)
+	}
+
+	return num, nil
+}

node/pkg/watchers/evm/watcher.go

@@ -229,12 +229,18 @@ 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.ethConn, err = connectors.NewBlockPollConnector(ctx, baseConnector, finalizer, 250*time.Millisecond, false)
+		pollConnector, err := connectors.NewBlockPollConnector(ctx, baseConnector, finalizer, 250*time.Millisecond, false)
 		if err != nil {
 			ethConnectionErrors.WithLabelValues(w.networkName, "dial_error").Inc()
 			p2p.DefaultRegistry.AddErrorCount(w.chainID, 1)
 			return fmt.Errorf("creating block poll connector failed: %w", err)
 		}
+		w.ethConn, err = connectors.NewArbitrumConnector(ctx, pollConnector)
+		if err != nil {
+			ethConnectionErrors.WithLabelValues(w.networkName, "dial_error").Inc()
+			p2p.DefaultRegistry.AddErrorCount(w.chainID, 1)
+			return fmt.Errorf("creating arbitrum connector failed: %w", err)
+		}
 	} else {
 		w.ethConn, err = connectors.NewEthereumConnector(timeout, w.networkName, w.url, w.contract, logger)
 		if err != nil {