Handle broken chain due to ParentHash mismatch in testnet

models/block.go

@@ -5,8 +5,10 @@ import (
 	"math/big"
 
 	"github.com/onflow/cadence"
+	"github.com/onflow/cadence/runtime/common"
 	"github.com/onflow/flow-go/fvm/evm/events"
 	"github.com/onflow/flow-go/fvm/evm/types"
+	"github.com/onflow/flow-go/fvm/systemcontracts"
 	"github.com/onflow/flow-go/model/flow"
 	gethCommon "github.com/onflow/go-ethereum/common"
 	gethCrypto "github.com/onflow/go-ethereum/crypto"
@@ -18,6 +20,19 @@ var (
 	EarliestBlockNumber = big.NewInt(0)
 )
 
+var testnetEVMBlockExecutedEventID = common.NewAddressLocation(
+	nil,
+	common.Address(systemcontracts.SystemContractsForChain(flow.Testnet).EVMContract.Address),
+	string(events.EventTypeBlockExecuted),
+).ID()
+
+// Testnet block heights at which the block hash calculation had a breaking change.
+// To properly handle this, we must assign the parent block hash, with a manual
+// mapping.
+var testnetParentHashMapping = map[uint64]gethCommon.Hash{
+	1385491: gethCommon.HexToHash("0xfc9a0204b12bc4875ed880300d07f27de4f9857be67d13cf72f53b09e8942ced"),
+}
+
 func GenesisBlock(chainID flow.ChainID) *Block {
 	block := types.GenesisBlock(chainID)
 	if chainID == flow.Testnet {
@@ -106,6 +121,14 @@ func decodeBlockEvent(event cadence.Event) (*Block, error) {
 		return nil, fmt.Errorf("failed to cadence decode block [%s]: %w", event.String(), err)
 	}
 
+	if event.EventType.ID() == testnetEVMBlockExecutedEventID {
+		for height, parentBlockHash := range testnetParentHashMapping {
+			if payload.Height == height {
+				payload.ParentBlockHash = parentBlockHash
+			}
+		}
+	}
+
 	return &Block{
 		Block: &types.Block{
 			ParentBlockHash:     payload.ParentBlockHash,