From 48bba206f6ee50e573b6c425c52fbcb558989013 Mon Sep 17 00:00:00 2001
From: David <david@taiko.xyz>
Date: Mon, 26 Jun 2023 04:11:58 +0800
Subject: [PATCH] feat(driver): check the mismatch of last verified block
 (#296)

---
 driver/chain_syncer/calldata/syncer.go | 43 +++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 4 deletions(-)

diff --git a/driver/chain_syncer/calldata/syncer.go b/driver/chain_syncer/calldata/syncer.go
index ffb8a0ddd..11295fa40 100644
--- a/driver/chain_syncer/calldata/syncer.go
+++ b/driver/chain_syncer/calldata/syncer.go
@@ -116,12 +116,35 @@ func (s *Syncer) onBlockProposed(
 
 	if !s.progressTracker.Triggered() {
 		// Check whteher we need to reorg the L2 chain at first.
-		reorged, l1CurrentToReset, lastInsertedBlockIDToReset, err := s.rpc.CheckL1Reorg(
-			ctx,
-			new(big.Int).Sub(event.Id, common.Big1),
+		// 1. Last verified block
+		var (
+			reorged                    bool
+			l1CurrentToReset           *types.Header
+			lastInsertedBlockIDToReset *big.Int
+			err                        error
 		)
+		reorged, err = s.checkLastVerifiedBlockMismatch(ctx)
 		if err != nil {
-			return fmt.Errorf("failed to check whether L1 chain has been reorged: %w", err)
+			return fmt.Errorf("failed to check if last verified block in L2 EE has been reorged: %w", err)
+		}
+
+		// 2. Parent block
+		if reorged {
+			genesisL1Header, err := s.rpc.GetGenesisL1Header(ctx)
+			if err != nil {
+				return fmt.Errorf("failed to fetch genesis L1 header: %w", err)
+			}
+
+			l1CurrentToReset = genesisL1Header
+			lastInsertedBlockIDToReset = common.Big0
+		} else {
+			reorged, l1CurrentToReset, lastInsertedBlockIDToReset, err = s.rpc.CheckL1Reorg(
+				ctx,
+				new(big.Int).Sub(event.Id, common.Big1),
+			)
+			if err != nil {
+				return fmt.Errorf("failed to check whether L1 chain has been reorged: %w", err)
+			}
 		}
 
 		if reorged {
@@ -427,3 +450,15 @@ func (s *Syncer) createExecutionPayloads(
 
 	return payload, nil
 }
+
+// checkLastVerifiedBlockMismatch checks if there is a mismatch between protocol's last verified block hash and
+// the corresponding L2 EE block hash.
+func (s *Syncer) checkLastVerifiedBlockMismatch(ctx context.Context) (bool, error) {
+	lastVerifiedBlockInfo := s.state.GetLatestVerifiedBlock()
+	l2Header, err := s.rpc.L2.HeaderByNumber(ctx, lastVerifiedBlockInfo.Height)
+	if err != nil {
+		return false, err
+	}
+
+	return l2Header.Hash() != lastVerifiedBlockInfo.Hash, nil
+}