plugeth/consensus/misc/eip4844/eip4844.go

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// Copyright 2023 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package eip4844
import (
"errors"
"fmt"
"math/big"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/params"
)
var (
minBlobGasPrice = big.NewInt(params.BlobTxMinBlobGasprice)
blobGaspriceUpdateFraction = big.NewInt(params.BlobTxBlobGaspriceUpdateFraction)
)
// VerifyEIP4844Header verifies the presence of the excessBlobGas field and that
// if the current block contains no transactions, the excessBlobGas is updated
// accordingly.
func VerifyEIP4844Header(parent, header *types.Header) error {
// Verify the header is not malformed
if header.ExcessBlobGas == nil {
return errors.New("header is missing excessBlobGas")
}
if header.BlobGasUsed == nil {
return errors.New("header is missing blobGasUsed")
}
// Verify that the blob gas used remains within reasonable limits.
if *header.BlobGasUsed > params.MaxBlobGasPerBlock {
return fmt.Errorf("blob gas used %d exceeds maximum allowance %d", *header.BlobGasUsed, params.MaxBlobGasPerBlock)
}
if *header.BlobGasUsed%params.BlobTxBlobGasPerBlob != 0 {
return fmt.Errorf("blob gas used %d not a multiple of blob gas per blob %d", header.BlobGasUsed, params.BlobTxBlobGasPerBlob)
}
// Verify the excessBlobGas is correct based on the parent header
var (
parentExcessBlobGas uint64
parentBlobGasUsed uint64
)
if parent.ExcessBlobGas != nil {
parentExcessBlobGas = *parent.ExcessBlobGas
parentBlobGasUsed = *parent.BlobGasUsed
}
expectedExcessBlobGas := CalcExcessBlobGas(parentExcessBlobGas, parentBlobGasUsed)
if *header.ExcessBlobGas != expectedExcessBlobGas {
return fmt.Errorf("invalid excessBlobGas: have %d, want %d, parent excessBlobGas %d, parent blobDataUsed %d",
*header.ExcessBlobGas, expectedExcessBlobGas, parentExcessBlobGas, parentBlobGasUsed)
}
return nil
}
// CalcExcessBlobGas calculates the excess blob gas after applying the set of
// blobs on top of the excess blob gas.
func CalcExcessBlobGas(parentExcessBlobGas uint64, parentBlobGasUsed uint64) uint64 {
excessBlobGas := parentExcessBlobGas + parentBlobGasUsed
if excessBlobGas < params.BlobTxTargetBlobGasPerBlock {
return 0
}
return excessBlobGas - params.BlobTxTargetBlobGasPerBlock
}
// CalcBlobFee calculates the blobfee from the header's excess blob gas field.
func CalcBlobFee(excessBlobGas uint64) *big.Int {
return fakeExponential(minBlobGasPrice, new(big.Int).SetUint64(excessBlobGas), blobGaspriceUpdateFraction)
}
// fakeExponential approximates factor * e ** (numerator / denominator) using
// Taylor expansion.
func fakeExponential(factor, numerator, denominator *big.Int) *big.Int {
var (
output = new(big.Int)
accum = new(big.Int).Mul(factor, denominator)
)
for i := 1; accum.Sign() > 0; i++ {
output.Add(output, accum)
accum.Mul(accum, numerator)
accum.Div(accum, denominator)
accum.Div(accum, big.NewInt(int64(i)))
}
return output.Div(output, denominator)
}