go-ethereum/consensus/ethash/consensus.go

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// Copyright 2017 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 ethash
import (
"errors"
"fmt"
"math/big"
"time"
mapset "github.com/deckarep/golang-set/v2"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/consensus"
"github.com/ethereum/go-ethereum/consensus/misc"
"github.com/ethereum/go-ethereum/consensus/misc/eip1559"
"github.com/ethereum/go-ethereum/core/state"
"github.com/ethereum/go-ethereum/core/tracing"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/params"
"github.com/ethereum/go-ethereum/rlp"
"github.com/ethereum/go-ethereum/trie"
"github.com/holiman/uint256"
"golang.org/x/crypto/sha3"
)
// Ethash proof-of-work protocol constants.
var (
FrontierBlockReward = uint256.NewInt(5e+18) // Block reward in wei for successfully mining a block
ByzantiumBlockReward = uint256.NewInt(3e+18) // Block reward in wei for successfully mining a block upward from Byzantium
ConstantinopleBlockReward = uint256.NewInt(2e+18) // Block reward in wei for successfully mining a block upward from Constantinople
maxUncles = 2 // Maximum number of uncles allowed in a single block
allowedFutureBlockTimeSeconds = int64(15) // Max seconds from current time allowed for blocks, before they're considered future blocks
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// calcDifficultyEip5133 is the difficulty adjustment algorithm as specified by EIP 5133.
// It offsets the bomb a total of 11.4M blocks.
// Specification EIP-5133: https://eips.ethereum.org/EIPS/eip-5133
calcDifficultyEip5133 = makeDifficultyCalculator(big.NewInt(11_400_000))
// calcDifficultyEip4345 is the difficulty adjustment algorithm as specified by EIP 4345.
// It offsets the bomb a total of 10.7M blocks.
// Specification EIP-4345: https://eips.ethereum.org/EIPS/eip-4345
calcDifficultyEip4345 = makeDifficultyCalculator(big.NewInt(10_700_000))
// calcDifficultyEip3554 is the difficulty adjustment algorithm as specified by EIP 3554.
// It offsets the bomb a total of 9.7M blocks.
// Specification EIP-3554: https://eips.ethereum.org/EIPS/eip-3554
calcDifficultyEip3554 = makeDifficultyCalculator(big.NewInt(9700000))
// calcDifficultyEip2384 is the difficulty adjustment algorithm as specified by EIP 2384.
// It offsets the bomb 4M blocks from Constantinople, so in total 9M blocks.
// Specification EIP-2384: https://eips.ethereum.org/EIPS/eip-2384
calcDifficultyEip2384 = makeDifficultyCalculator(big.NewInt(9000000))
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// calcDifficultyConstantinople is the difficulty adjustment algorithm for Constantinople.
// It returns the difficulty that a new block should have when created at time given the
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// parent block's time and difficulty. The calculation uses the Byzantium rules, but with
// bomb offset 5M.
// Specification EIP-1234: https://eips.ethereum.org/EIPS/eip-1234
calcDifficultyConstantinople = makeDifficultyCalculator(big.NewInt(5000000))
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// calcDifficultyByzantium is the difficulty adjustment algorithm. It returns
// the difficulty that a new block should have when created at time given the
// parent block's time and difficulty. The calculation uses the Byzantium rules.
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// Specification EIP-649: https://eips.ethereum.org/EIPS/eip-649
calcDifficultyByzantium = makeDifficultyCalculator(big.NewInt(3000000))
)
// Various error messages to mark blocks invalid. These should be private to
// prevent engine specific errors from being referenced in the remainder of the
// codebase, inherently breaking if the engine is swapped out. Please put common
// error types into the consensus package.
var (
errOlderBlockTime = errors.New("timestamp older than parent")
errTooManyUncles = errors.New("too many uncles")
errDuplicateUncle = errors.New("duplicate uncle")
errUncleIsAncestor = errors.New("uncle is ancestor")
errDanglingUncle = errors.New("uncle's parent is not ancestor")
)
// Author implements consensus.Engine, returning the header's coinbase as the
// proof-of-work verified author of the block.
func (ethash *Ethash) Author(header *types.Header) (common.Address, error) {
return header.Coinbase, nil
}
// VerifyHeader checks whether a header conforms to the consensus rules of the
// stock Ethereum ethash engine.
func (ethash *Ethash) VerifyHeader(chain consensus.ChainHeaderReader, header *types.Header) error {
// Short circuit if the header is known, or its parent not
number := header.Number.Uint64()
if chain.GetHeader(header.Hash(), number) != nil {
return nil
}
parent := chain.GetHeader(header.ParentHash, number-1)
if parent == nil {
return consensus.ErrUnknownAncestor
}
// Sanity checks passed, do a proper verification
return ethash.verifyHeader(chain, header, parent, false, time.Now().Unix())
}
// VerifyHeaders is similar to VerifyHeader, but verifies a batch of headers
// concurrently. The method returns a quit channel to abort the operations and
// a results channel to retrieve the async verifications.
func (ethash *Ethash) VerifyHeaders(chain consensus.ChainHeaderReader, headers []*types.Header) (chan<- struct{}, <-chan error) {
// If we're running a full engine faking, accept any input as valid
if ethash.fakeFull || len(headers) == 0 {
abort, results := make(chan struct{}), make(chan error, len(headers))
for i := 0; i < len(headers); i++ {
results <- nil
}
return abort, results
}
abort := make(chan struct{})
results := make(chan error, len(headers))
unixNow := time.Now().Unix()
go func() {
for i, header := range headers {
var parent *types.Header
if i == 0 {
parent = chain.GetHeader(headers[0].ParentHash, headers[0].Number.Uint64()-1)
} else if headers[i-1].Hash() == headers[i].ParentHash {
parent = headers[i-1]
}
var err error
if parent == nil {
err = consensus.ErrUnknownAncestor
} else {
err = ethash.verifyHeader(chain, header, parent, false, unixNow)
}
select {
case <-abort:
return
case results <- err:
}
}
}()
return abort, results
}
// VerifyUncles verifies that the given block's uncles conform to the consensus
// rules of the stock Ethereum ethash engine.
func (ethash *Ethash) VerifyUncles(chain consensus.ChainReader, block *types.Block) error {
// If we're running a full engine faking, accept any input as valid
if ethash.fakeFull {
return nil
}
// Verify that there are at most 2 uncles included in this block
if len(block.Uncles()) > maxUncles {
return errTooManyUncles
}
if len(block.Uncles()) == 0 {
return nil
}
// Gather the set of past uncles and ancestors
uncles, ancestors := mapset.NewSet[common.Hash](), make(map[common.Hash]*types.Header)
number, parent := block.NumberU64()-1, block.ParentHash()
for i := 0; i < 7; i++ {
ancestorHeader := chain.GetHeader(parent, number)
if ancestorHeader == nil {
break
}
ancestors[parent] = ancestorHeader
// If the ancestor doesn't have any uncles, we don't have to iterate them
if ancestorHeader.UncleHash != types.EmptyUncleHash {
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// Need to add those uncles to the banned list too
ancestor := chain.GetBlock(parent, number)
if ancestor == nil {
break
}
for _, uncle := range ancestor.Uncles() {
uncles.Add(uncle.Hash())
}
}
parent, number = ancestorHeader.ParentHash, number-1
}
ancestors[block.Hash()] = block.Header()
uncles.Add(block.Hash())
// Verify each of the uncles that it's recent, but not an ancestor
for _, uncle := range block.Uncles() {
// Make sure every uncle is rewarded only once
hash := uncle.Hash()
if uncles.Contains(hash) {
return errDuplicateUncle
}
uncles.Add(hash)
// Make sure the uncle has a valid ancestry
if ancestors[hash] != nil {
return errUncleIsAncestor
}
if ancestors[uncle.ParentHash] == nil || uncle.ParentHash == block.ParentHash() {
return errDanglingUncle
}
if err := ethash.verifyHeader(chain, uncle, ancestors[uncle.ParentHash], true, time.Now().Unix()); err != nil {
return err
}
}
return nil
}
// verifyHeader checks whether a header conforms to the consensus rules of the
// stock Ethereum ethash engine.
// See YP section 4.3.4. "Block Header Validity"
func (ethash *Ethash) verifyHeader(chain consensus.ChainHeaderReader, header, parent *types.Header, uncle bool, unixNow int64) error {
// Ensure that the header's extra-data section is of a reasonable size
if uint64(len(header.Extra)) > params.MaximumExtraDataSize {
return fmt.Errorf("extra-data too long: %d > %d", len(header.Extra), params.MaximumExtraDataSize)
}
// Verify the header's timestamp
if !uncle {
if header.Time > uint64(unixNow+allowedFutureBlockTimeSeconds) {
return consensus.ErrFutureBlock
}
}
if header.Time <= parent.Time {
return errOlderBlockTime
}
// Verify the block's difficulty based on its timestamp and parent's difficulty
expected := ethash.CalcDifficulty(chain, header.Time, parent)
if expected.Cmp(header.Difficulty) != 0 {
return fmt.Errorf("invalid difficulty: have %v, want %v", header.Difficulty, expected)
}
// Verify that the gas limit is <= 2^63-1
if header.GasLimit > params.MaxGasLimit {
return fmt.Errorf("invalid gasLimit: have %v, max %v", header.GasLimit, params.MaxGasLimit)
}
// Verify that the gasUsed is <= gasLimit
if header.GasUsed > header.GasLimit {
return fmt.Errorf("invalid gasUsed: have %d, gasLimit %d", header.GasUsed, header.GasLimit)
}
// Verify the block's gas usage and (if applicable) verify the base fee.
if !chain.Config().IsLondon(header.Number) {
// Verify BaseFee not present before EIP-1559 fork.
if header.BaseFee != nil {
return fmt.Errorf("invalid baseFee before fork: have %d, expected 'nil'", header.BaseFee)
}
if err := misc.VerifyGaslimit(parent.GasLimit, header.GasLimit); err != nil {
return err
}
} else if err := eip1559.VerifyEIP1559Header(chain.Config(), parent, header); err != nil {
// Verify the header's EIP-1559 attributes.
return err
}
// Verify that the block number is parent's +1
if diff := new(big.Int).Sub(header.Number, parent.Number); diff.Cmp(big.NewInt(1)) != 0 {
return consensus.ErrInvalidNumber
}
if chain.Config().IsShanghai(header.Number, header.Time) {
return errors.New("ethash does not support shanghai fork")
}
// Verify the non-existence of withdrawalsHash.
if header.WithdrawalsHash != nil {
return fmt.Errorf("invalid withdrawalsHash: have %x, expected nil", header.WithdrawalsHash)
}
if chain.Config().IsCancun(header.Number, header.Time) {
return errors.New("ethash does not support cancun fork")
}
// Verify the non-existence of cancun-specific header fields
switch {
case header.ExcessBlobGas != nil:
return fmt.Errorf("invalid excessBlobGas: have %d, expected nil", header.ExcessBlobGas)
case header.BlobGasUsed != nil:
return fmt.Errorf("invalid blobGasUsed: have %d, expected nil", header.BlobGasUsed)
case header.ParentBeaconRoot != nil:
return fmt.Errorf("invalid parentBeaconRoot, have %#x, expected nil", header.ParentBeaconRoot)
}
// Add some fake checks for tests
if ethash.fakeDelay != nil {
time.Sleep(*ethash.fakeDelay)
}
if ethash.fakeFail != nil && *ethash.fakeFail == header.Number.Uint64() {
return errors.New("invalid tester pow")
}
// If all checks passed, validate any special fields for hard forks
if err := misc.VerifyDAOHeaderExtraData(chain.Config(), header); err != nil {
return err
}
return nil
}
// CalcDifficulty is the difficulty adjustment algorithm. It returns
// the difficulty that a new block should have when created at time
// given the parent block's time and difficulty.
func (ethash *Ethash) CalcDifficulty(chain consensus.ChainHeaderReader, time uint64, parent *types.Header) *big.Int {
return CalcDifficulty(chain.Config(), time, parent)
}
// CalcDifficulty is the difficulty adjustment algorithm. It returns
// the difficulty that a new block should have when created at time
// given the parent block's time and difficulty.
func CalcDifficulty(config *params.ChainConfig, time uint64, parent *types.Header) *big.Int {
next := new(big.Int).Add(parent.Number, big1)
switch {
case config.IsGrayGlacier(next):
return calcDifficultyEip5133(time, parent)
case config.IsArrowGlacier(next):
return calcDifficultyEip4345(time, parent)
case config.IsLondon(next):
return calcDifficultyEip3554(time, parent)
case config.IsMuirGlacier(next):
return calcDifficultyEip2384(time, parent)
case config.IsConstantinople(next):
return calcDifficultyConstantinople(time, parent)
case config.IsByzantium(next):
return calcDifficultyByzantium(time, parent)
case config.IsHomestead(next):
return calcDifficultyHomestead(time, parent)
default:
return calcDifficultyFrontier(time, parent)
}
}
// Some weird constants to avoid constant memory allocs for them.
var (
expDiffPeriod = big.NewInt(100000)
big1 = big.NewInt(1)
big2 = big.NewInt(2)
big9 = big.NewInt(9)
big10 = big.NewInt(10)
bigMinus99 = big.NewInt(-99)
)
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// makeDifficultyCalculator creates a difficultyCalculator with the given bomb-delay.
// the difficulty is calculated with Byzantium rules, which differs from Homestead in
// how uncles affect the calculation
func makeDifficultyCalculator(bombDelay *big.Int) func(time uint64, parent *types.Header) *big.Int {
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// Note, the calculations below looks at the parent number, which is 1 below
// the block number. Thus we remove one from the delay given
bombDelayFromParent := new(big.Int).Sub(bombDelay, big1)
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return func(time uint64, parent *types.Header) *big.Int {
// https://github.com/ethereum/EIPs/issues/100.
// algorithm:
// diff = (parent_diff +
// (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
// ) + 2^(periodCount - 2)
bigTime := new(big.Int).SetUint64(time)
bigParentTime := new(big.Int).SetUint64(parent.Time)
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// holds intermediate values to make the algo easier to read & audit
x := new(big.Int)
y := new(big.Int)
// (2 if len(parent_uncles) else 1) - (block_timestamp - parent_timestamp) // 9
x.Sub(bigTime, bigParentTime)
x.Div(x, big9)
if parent.UncleHash == types.EmptyUncleHash {
x.Sub(big1, x)
} else {
x.Sub(big2, x)
}
// max((2 if len(parent_uncles) else 1) - (block_timestamp - parent_timestamp) // 9, -99)
if x.Cmp(bigMinus99) < 0 {
x.Set(bigMinus99)
}
// parent_diff + (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
y.Div(parent.Difficulty, params.DifficultyBoundDivisor)
x.Mul(y, x)
x.Add(parent.Difficulty, x)
// minimum difficulty can ever be (before exponential factor)
if x.Cmp(params.MinimumDifficulty) < 0 {
x.Set(params.MinimumDifficulty)
}
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// calculate a fake block number for the ice-age delay
// Specification: https://eips.ethereum.org/EIPS/eip-1234
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fakeBlockNumber := new(big.Int)
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if parent.Number.Cmp(bombDelayFromParent) >= 0 {
fakeBlockNumber = fakeBlockNumber.Sub(parent.Number, bombDelayFromParent)
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}
// for the exponential factor
periodCount := fakeBlockNumber
periodCount.Div(periodCount, expDiffPeriod)
// the exponential factor, commonly referred to as "the bomb"
// diff = diff + 2^(periodCount - 2)
if periodCount.Cmp(big1) > 0 {
y.Sub(periodCount, big2)
y.Exp(big2, y, nil)
x.Add(x, y)
}
return x
}
}
// calcDifficultyHomestead is the difficulty adjustment algorithm. It returns
// the difficulty that a new block should have when created at time given the
// parent block's time and difficulty. The calculation uses the Homestead rules.
func calcDifficultyHomestead(time uint64, parent *types.Header) *big.Int {
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-2.md
// algorithm:
// diff = (parent_diff +
// (parent_diff / 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99))
// ) + 2^(periodCount - 2)
bigTime := new(big.Int).SetUint64(time)
bigParentTime := new(big.Int).SetUint64(parent.Time)
// holds intermediate values to make the algo easier to read & audit
x := new(big.Int)
y := new(big.Int)
// 1 - (block_timestamp - parent_timestamp) // 10
x.Sub(bigTime, bigParentTime)
x.Div(x, big10)
x.Sub(big1, x)
// max(1 - (block_timestamp - parent_timestamp) // 10, -99)
if x.Cmp(bigMinus99) < 0 {
x.Set(bigMinus99)
}
// (parent_diff + parent_diff // 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99))
y.Div(parent.Difficulty, params.DifficultyBoundDivisor)
x.Mul(y, x)
x.Add(parent.Difficulty, x)
// minimum difficulty can ever be (before exponential factor)
if x.Cmp(params.MinimumDifficulty) < 0 {
x.Set(params.MinimumDifficulty)
}
// for the exponential factor
periodCount := new(big.Int).Add(parent.Number, big1)
periodCount.Div(periodCount, expDiffPeriod)
// the exponential factor, commonly referred to as "the bomb"
// diff = diff + 2^(periodCount - 2)
if periodCount.Cmp(big1) > 0 {
y.Sub(periodCount, big2)
y.Exp(big2, y, nil)
x.Add(x, y)
}
return x
}
// calcDifficultyFrontier is the difficulty adjustment algorithm. It returns the
// difficulty that a new block should have when created at time given the parent
// block's time and difficulty. The calculation uses the Frontier rules.
func calcDifficultyFrontier(time uint64, parent *types.Header) *big.Int {
diff := new(big.Int)
adjust := new(big.Int).Div(parent.Difficulty, params.DifficultyBoundDivisor)
bigTime := new(big.Int)
bigParentTime := new(big.Int)
bigTime.SetUint64(time)
bigParentTime.SetUint64(parent.Time)
if bigTime.Sub(bigTime, bigParentTime).Cmp(params.DurationLimit) < 0 {
diff.Add(parent.Difficulty, adjust)
} else {
diff.Sub(parent.Difficulty, adjust)
}
if diff.Cmp(params.MinimumDifficulty) < 0 {
diff.Set(params.MinimumDifficulty)
}
periodCount := new(big.Int).Add(parent.Number, big1)
periodCount.Div(periodCount, expDiffPeriod)
if periodCount.Cmp(big1) > 0 {
// diff = diff + 2^(periodCount - 2)
expDiff := periodCount.Sub(periodCount, big2)
expDiff.Exp(big2, expDiff, nil)
diff.Add(diff, expDiff)
diff = math.BigMax(diff, params.MinimumDifficulty)
}
return diff
}
// Exported for fuzzing
var FrontierDifficultyCalculator = calcDifficultyFrontier
var HomesteadDifficultyCalculator = calcDifficultyHomestead
var DynamicDifficultyCalculator = makeDifficultyCalculator
// Prepare implements consensus.Engine, initializing the difficulty field of a
// header to conform to the ethash protocol. The changes are done inline.
func (ethash *Ethash) Prepare(chain consensus.ChainHeaderReader, header *types.Header) error {
parent := chain.GetHeader(header.ParentHash, header.Number.Uint64()-1)
if parent == nil {
return consensus.ErrUnknownAncestor
}
header.Difficulty = ethash.CalcDifficulty(chain, header.Time, parent)
return nil
}
// Finalize implements consensus.Engine, accumulating the block and uncle rewards.
func (ethash *Ethash) Finalize(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB, body *types.Body) {
// Accumulate any block and uncle rewards
accumulateRewards(chain.Config(), state, header, body.Uncles)
}
// FinalizeAndAssemble implements consensus.Engine, accumulating the block and
// uncle rewards, setting the final state and assembling the block.
func (ethash *Ethash) FinalizeAndAssemble(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB, body *types.Body, receipts []*types.Receipt) (*types.Block, error) {
if len(body.Withdrawals) > 0 {
return nil, errors.New("ethash does not support withdrawals")
}
// Finalize block
ethash.Finalize(chain, header, state, body)
// Assign the final state root to header.
header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
// Header seems complete, assemble into a block and return
return types.NewBlock(header, body.Transactions, body.Uncles, receipts, trie.NewStackTrie(nil)), nil
}
// SealHash returns the hash of a block prior to it being sealed.
func (ethash *Ethash) SealHash(header *types.Header) (hash common.Hash) {
hasher := sha3.NewLegacyKeccak256()
enc := []interface{}{
header.ParentHash,
header.UncleHash,
header.Coinbase,
header.Root,
header.TxHash,
header.ReceiptHash,
header.Bloom,
header.Difficulty,
header.Number,
header.GasLimit,
header.GasUsed,
header.Time,
header.Extra,
}
if header.BaseFee != nil {
enc = append(enc, header.BaseFee)
}
if header.WithdrawalsHash != nil {
panic("withdrawal hash set on ethash")
}
if header.ExcessBlobGas != nil {
panic("excess blob gas set on ethash")
}
if header.BlobGasUsed != nil {
panic("blob gas used set on ethash")
}
if header.ParentBeaconRoot != nil {
panic("parent beacon root set on ethash")
}
rlp.Encode(hasher, enc)
hasher.Sum(hash[:0])
return hash
}
// Some weird constants to avoid constant memory allocs for them.
var (
u256_8 = uint256.NewInt(8)
u256_32 = uint256.NewInt(32)
)
// AccumulateRewards credits the coinbase of the given block with the mining
// reward. The total reward consists of the static block reward and rewards for
// included uncles. The coinbase of each uncle block is also rewarded.
func accumulateRewards(config *params.ChainConfig, stateDB *state.StateDB, header *types.Header, uncles []*types.Header) {
// Select the correct block reward based on chain progression
blockReward := FrontierBlockReward
if config.IsByzantium(header.Number) {
blockReward = ByzantiumBlockReward
}
if config.IsConstantinople(header.Number) {
blockReward = ConstantinopleBlockReward
}
// Accumulate the rewards for the miner and any included uncles
reward := new(uint256.Int).Set(blockReward)
r := new(uint256.Int)
hNum, _ := uint256.FromBig(header.Number)
for _, uncle := range uncles {
uNum, _ := uint256.FromBig(uncle.Number)
r.AddUint64(uNum, 8)
r.Sub(r, hNum)
r.Mul(r, blockReward)
r.Div(r, u256_8)
stateDB.AddBalance(uncle.Coinbase, r, tracing.BalanceIncreaseRewardMineUncle)
r.Div(blockReward, u256_32)
reward.Add(reward, r)
}
stateDB.AddBalance(header.Coinbase, reward, tracing.BalanceIncreaseRewardMineBlock)
}