consensus/misc/4844: add exception for OP-Stack in CalcBlobFee

consensus/misc/eip4844/eip4844.go

@@ -81,6 +81,16 @@ func CalcExcessBlobGas(config *params.ChainConfig, parent *types.Header, headTim
 
 // CalcBlobFee calculates the blobfee from the header's excess blob gas field.
 func CalcBlobFee(config *params.ChainConfig, header *types.Header) *big.Int {
+	// OP-Stack chains don't support blobs, but still set the excessBlobGas field (always to zero).
+	// So this function is called in many places for OP-Stack chains too. In order to not require
+	// a blob schedule in the chain config, we short circuit here.
+	if config.IsOptimism() {
+		if config.BlobScheduleConfig != nil || header.ExcessBlobGas == nil || *header.ExcessBlobGas != 0 {
+			panic("OP-Stack: CalcBlobFee: unexpected blob schedule or excess blob gas")
+		}
+		return minBlobGasPrice
+	}
+
 	var frac uint64
 	switch config.LatestFork(header.Time) {
 	case forks.Prague:

consensus/misc/eip4844/eip4844_test.go

@@ -21,6 +21,8 @@ import (
 	"math/big"
 	"testing"
 
+	"github.com/stretchr/testify/require"
+
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/params"
 )
@@ -90,6 +92,28 @@ func TestCalcBlobFee(t *testing.T) {
 	}
 }
 
+func TestCalcBlobFeeOPStack(t *testing.T) {
+	zero := uint64(0)
+	header := &types.Header{ExcessBlobGas: &zero}
+	// any non-nil optimism confic should do
+	config := &params.ChainConfig{Optimism: new(params.OptimismConfig)}
+	bfee := CalcBlobFee(config, header)
+	require.Equal(t, int64(1), bfee.Int64())
+
+	reqPanic := func() {
+		require.PanicsWithValue(t,
+			"OP-Stack: CalcBlobFee: unexpected blob schedule or excess blob gas",
+			func() { CalcBlobFee(config, header) })
+	}
+	(*header.ExcessBlobGas)++
+	reqPanic()
+	header.ExcessBlobGas = nil
+	reqPanic()
+	header.ExcessBlobGas = &zero
+	config.BlobScheduleConfig = params.DefaultBlobSchedule
+	reqPanic()
+}
+
 func TestFakeExponential(t *testing.T) {
 	tests := []struct {
 		factor      int64