op-node: Audit use of L1 State

The L1 State can return uninitialized values. I have checked every
usage in the op-node and either check the return value from L1
state if is important or let the empty value through.

op-node/rollup/driver/conf_depth.go

@@ -6,7 +6,6 @@ import (
 	"github.com/ethereum-optimism/optimism/op-node/eth"
 	"github.com/ethereum-optimism/optimism/op-node/rollup/derive"
 	"github.com/ethereum/go-ethereum"
-	"github.com/ethereum/go-ethereum/common"
 )
 
 // confDepth is an util that wraps the L1 input fetcher used in the pipeline,
@@ -33,7 +32,10 @@ func (c *confDepth) L1BlockRefByNumber(ctx context.Context, num uint64) (eth.L1B
 
 	// Don't apply the conf depth is l1Head is empty (as it is during the startup case before the l1State is initialized).
 	l1Head := c.l1Head()
-	if num == 0 || c.depth == 0 || num+c.depth <= l1Head.Number || l1Head.Hash == (common.Hash{}) {
+	if l1Head == (eth.L1BlockRef{}) {
+		return c.L1Fetcher.L1BlockRefByNumber(ctx, num)
+	}
+	if num == 0 || c.depth == 0 || num+c.depth <= l1Head.Number {
 		return c.L1Fetcher.L1BlockRefByNumber(ctx, num)
 	}
 	return eth.L1BlockRef{}, ethereum.NotFound

op-node/rollup/driver/l1_state.go

@@ -63,14 +63,20 @@ func (s *L1State) HandleNewL1FinalizedBlock(finalized eth.L1BlockRef) {
 	s.l1Finalized = finalized
 }
 
+// L1Head returns either the stored L1 head or an empty block reference
+// if the L1 Head has not been initialized yet.
 func (s *L1State) L1Head() eth.L1BlockRef {
 	return s.l1Head
 }
 
+// L1Safe returns either the stored L1 safe block or an empty block reference
+// if the L1 safe block has not been initialized yet.
 func (s *L1State) L1Safe() eth.L1BlockRef {
 	return s.l1Safe
 }
 
+// L1Finalized returns either the stored L1 finalized block or an empty block reference
+// if the L1 finalized block has not been initialized yet.
 func (s *L1State) L1Finalized() eth.L1BlockRef {
 	return s.l1Finalized
 }

op-node/rollup/driver/state.go

@@ -134,8 +134,13 @@ func (s *Driver) createNewL2Block(ctx context.Context) error {
 	l2Safe := s.derivation.SafeL2Head()
 	l2Finalized := s.derivation.Finalized()
 
+	l1Head := s.l1State.L1Head()
+	if l1Head == (eth.L1BlockRef{}) {
+		return derive.NewTemporaryError(errors.New("L1 Head in L1 State is not initizalited yet"))
+	}
+
 	// Figure out which L1 origin block we're going to be building on top of.
-	l1Origin, err := s.l1OriginSelector.FindL1Origin(ctx, s.l1State.L1Head(), l2Head)
+	l1Origin, err := s.l1OriginSelector.FindL1Origin(ctx, l1Head, l2Head)
 	if err != nil {
 		s.log.Error("Error finding next L1 Origin", "err", err)
 		return err
@@ -261,9 +266,8 @@ func (s *Driver) eventLoop() {
 
 		case <-l2BlockCreationReqCh:
 			s.snapshot("L2 Block Creation Request")
-			l1Head := s.l1State.L1Head()
 			if !s.idleDerivation {
-				s.log.Warn("not creating block, node is deriving new l2 data", "head_l1", l1Head)
+				s.log.Warn("not creating block, node is deriving new l2 data", "head_l1", s.l1State.L1Head())
 				break
 			}
 			ctx, cancel := context.WithTimeout(ctx, 20*time.Minute)