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