consensus, core, eth/downloader, params: 4844 chain validation (#27382)

consensus/misc/eip1559.go

@@ -27,10 +27,10 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
-// VerifyEip1559Header verifies some header attributes which were changed in EIP-1559,
+// VerifyEIP1559Header verifies some header attributes which were changed in EIP-1559,
 // - gas limit check
 // - basefee check
-func VerifyEip1559Header(config *params.ChainConfig, parent, header *types.Header) error {
+func VerifyEIP1559Header(config *params.ChainConfig, parent, header *types.Header) error {
 	// Verify that the gas limit remains within allowed bounds
 	parentGasLimit := parent.GasLimit
 	if !config.IsLondon(parent.Number) {

consensus/misc/eip1559_test.go

@@ -95,7 +95,7 @@ func TestBlockGasLimits(t *testing.T) {
 			BaseFee:  initial,
 			Number:   big.NewInt(tc.pNum + 1),
 		}
-		err := VerifyEip1559Header(config(), parent, header)
+		err := VerifyEIP1559Header(config(), parent, header)
 		if tc.ok && err != nil {
 			t.Errorf("test %d: Expected valid header: %s", i, err)
 		}

consensus/misc/eip4844.go

@@ -17,8 +17,11 @@
 package misc
 
 import (
+	"errors"
+	"fmt"
 	"math/big"
 
+	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/params"
 )
 
@@ -27,13 +30,54 @@ var (
 	dataGaspriceUpdateFraction = big.NewInt(params.BlobTxDataGaspriceUpdateFraction)
 )
 
-// CalcBlobFee calculates the blobfee from the header's excess data gas field.
-func CalcBlobFee(excessDataGas *big.Int) *big.Int {
-	// If this block does not yet have EIP-4844 enabled, return the starting fee
-	if excessDataGas == nil {
-		return big.NewInt(params.BlobTxMinDataGasprice)
+// VerifyEIP4844Header verifies the presence of the excessDataGas field and that
+// if the current block contains no transactions, the excessDataGas is updated
+// accordingly.
+func VerifyEIP4844Header(parent, header *types.Header) error {
+	// Verify the header is not malformed
+	if header.ExcessDataGas == nil {
+		return errors.New("header is missing excessDataGas")
 	}
-	return fakeExponential(minDataGasPrice, excessDataGas, dataGaspriceUpdateFraction)
+	if header.DataGasUsed == nil {
+		return errors.New("header is missing dataGasUsed")
+	}
+	// Verify that the data gas used remains within reasonable limits.
+	if *header.DataGasUsed > params.BlobTxMaxDataGasPerBlock {
+		return fmt.Errorf("data gas used %d exceeds maximum allowance %d", *header.DataGasUsed, params.BlobTxMaxDataGasPerBlock)
+	}
+	if *header.DataGasUsed%params.BlobTxDataGasPerBlob != 0 {
+		return fmt.Errorf("data gas used %d not a multiple of data gas per blob %d", header.DataGasUsed, params.BlobTxDataGasPerBlob)
+	}
+	// Verify the excessDataGas is correct based on the parent header
+	var (
+		parentExcessDataGas uint64
+		parentDataGasUsed   uint64
+	)
+	if parent.ExcessDataGas != nil {
+		parentExcessDataGas = *parent.ExcessDataGas
+		parentDataGasUsed = *parent.DataGasUsed
+	}
+	expectedExcessDataGas := CalcExcessDataGas(parentExcessDataGas, parentDataGasUsed)
+	if *header.ExcessDataGas != expectedExcessDataGas {
+		return fmt.Errorf("invalid excessDataGas: have %d, want %d, parent excessDataGas %d, parent blobDataUsed %d",
+			*header.ExcessDataGas, expectedExcessDataGas, parentExcessDataGas, parentDataGasUsed)
+	}
+	return nil
+}
+
+// CalcExcessDataGas calculates the excess data gas after applying the set of
+// blobs on top of the excess data gas.
+func CalcExcessDataGas(parentExcessDataGas uint64, parentDataGasUsed uint64) uint64 {
+	excessDataGas := parentExcessDataGas + parentDataGasUsed
+	if excessDataGas < params.BlobTxTargetDataGasPerBlock {
+		return 0
+	}
+	return excessDataGas - params.BlobTxTargetDataGasPerBlock
+}
+
+// CalcBlobFee calculates the blobfee from the header's excess data gas field.
+func CalcBlobFee(excessDataGas uint64) *big.Int {
+	return fakeExponential(minDataGasPrice, new(big.Int).SetUint64(excessDataGas), dataGaspriceUpdateFraction)
 }
 
 // fakeExponential approximates factor * e ** (numerator / denominator) using

consensus/misc/eip4844_test.go

@@ -24,9 +24,42 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
+func TestCalcExcessDataGas(t *testing.T) {
+	var tests = []struct {
+		excess uint64
+		blobs  uint64
+		want   uint64
+	}{
+		// The excess data gas should not increase from zero if the used blob
+		// slots are below - or equal - to the target.
+		{0, 0, 0},
+		{0, 1, 0},
+		{0, params.BlobTxTargetDataGasPerBlock / params.BlobTxDataGasPerBlob, 0},
+
+		// If the target data gas is exceeded, the excessDataGas should increase
+		// by however much it was overshot
+		{0, (params.BlobTxTargetDataGasPerBlock / params.BlobTxDataGasPerBlob) + 1, params.BlobTxDataGasPerBlob},
+		{1, (params.BlobTxTargetDataGasPerBlock / params.BlobTxDataGasPerBlob) + 1, params.BlobTxDataGasPerBlob + 1},
+		{1, (params.BlobTxTargetDataGasPerBlock / params.BlobTxDataGasPerBlob) + 2, 2*params.BlobTxDataGasPerBlob + 1},
+
+		// The excess data gas should decrease by however much the target was
+		// under-shot, capped at zero.
+		{params.BlobTxTargetDataGasPerBlock, params.BlobTxTargetDataGasPerBlock / params.BlobTxDataGasPerBlob, params.BlobTxTargetDataGasPerBlock},
+		{params.BlobTxTargetDataGasPerBlock, (params.BlobTxTargetDataGasPerBlock / params.BlobTxDataGasPerBlob) - 1, params.BlobTxDataGasPerBlob},
+		{params.BlobTxTargetDataGasPerBlock, (params.BlobTxTargetDataGasPerBlock / params.BlobTxDataGasPerBlob) - 2, 0},
+		{params.BlobTxDataGasPerBlob - 1, (params.BlobTxTargetDataGasPerBlock / params.BlobTxDataGasPerBlob) - 1, 0},
+	}
+	for _, tt := range tests {
+		result := CalcExcessDataGas(tt.excess, tt.blobs*params.BlobTxDataGasPerBlob)
+		if result != tt.want {
+			t.Errorf("excess data gas mismatch: have %v, want %v", result, tt.want)
+		}
+	}
+}
+
 func TestCalcBlobFee(t *testing.T) {
 	tests := []struct {
-		excessDataGas int64
+		excessDataGas uint64
 		blobfee       int64
 	}{
 		{0, 1},
@@ -34,12 +67,8 @@ func TestCalcBlobFee(t *testing.T) {
 		{1542707, 2},
 		{10 * 1024 * 1024, 111},
 	}
-	have := CalcBlobFee(nil)
-	if have.Int64() != params.BlobTxMinDataGasprice {
-		t.Errorf("nil test: blobfee mismatch: have %v, want %v", have, params.BlobTxMinDataGasprice)
-	}
 	for i, tt := range tests {
-		have := CalcBlobFee(big.NewInt(tt.excessDataGas))
+		have := CalcBlobFee(tt.excessDataGas)
 		if have.Int64() != tt.blobfee {
 			t.Errorf("test %d: blobfee mismatch: have %v want %v", i, have, tt.blobfee)
 		}