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-rw-r--r--consensus/ethash/consensus.go496
1 files changed, 496 insertions, 0 deletions
diff --git a/consensus/ethash/consensus.go b/consensus/ethash/consensus.go
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+++ b/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 (
+ "bytes"
+ "errors"
+ "fmt"
+ "math/big"
+ "runtime"
+ "sync/atomic"
+ "time"
+
+ "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/core/state"
+ "github.com/ethereum/go-ethereum/core/types"
+ "github.com/ethereum/go-ethereum/params"
+ set "gopkg.in/fatih/set.v0"
+)
+
+// Ethash proof-of-work protocol constants.
+var (
+ blockReward *big.Int = big.NewInt(5e+18) // Block reward in wei for successfully mining a block
+ maxUncles = 2 // Maximum number of uncles allowed in a single block
+)
+
+var (
+ ErrInvalidChain = errors.New("invalid header chain")
+ ErrParentUnknown = errors.New("parent not known locally")
+ ErrFutureBlock = errors.New("block in the future")
+ ErrLargeBlockTimestamp = errors.New("timestamp too big")
+ ErrZeroBlockTime = errors.New("timestamp equals parent's")
+ ErrInvalidNumber = errors.New("invalid block number")
+ 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")
+ ErrNonceOutOfRange = errors.New("nonce out of range")
+ ErrInvalidDifficulty = errors.New("non-positive difficulty")
+ ErrInvalidMixDigest = errors.New("invalid mix digest")
+ ErrInvalidPoW = errors.New("invalid proof-of-work")
+)
+
+// VerifyHeader checks whether a header conforms to the consensus rules of the
+// stock Ethereum ethash engine.
+func (ethash *Ethash) VerifyHeader(chain consensus.ChainReader, header *types.Header, seal bool) error {
+ // If we're running a full engine faking, accept any input as valid
+ if ethash.fakeFull {
+ return nil
+ }
+ // Short circuit if the header is known, or it's 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 ErrParentUnknown
+ }
+ // Sanity checks passed, do a proper verification
+ return ethash.verifyHeader(chain, header, parent, false, seal)
+}
+
+// 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.ChainReader, headers []*types.Header, seals []bool) (chan<- struct{}, <-chan error) {
+ // If we're running a full engine faking, accept any input as valid
+ if ethash.fakeFull {
+ abort, results := make(chan struct{}), make(chan error, len(headers))
+ for i := 0; i < len(headers); i++ {
+ results <- nil
+ }
+ return abort, results
+ }
+ // Spawn as many workers as allowed threads
+ workers := runtime.GOMAXPROCS(0)
+ if len(headers) < workers {
+ workers = len(headers)
+ }
+ // Create a task channel and spawn the verifiers
+ type result struct {
+ index int
+ err error
+ }
+ inputs := make(chan int, workers)
+ outputs := make(chan result, len(headers))
+
+ var badblock uint64
+ for i := 0; i < workers; i++ {
+ go func() {
+ for index := range inputs {
+ // If we've found a bad block already before this, stop validating
+ if bad := atomic.LoadUint64(&badblock); bad != 0 && bad <= headers[index].Number.Uint64() {
+ outputs <- result{index: index, err: ErrInvalidChain}
+ continue
+ }
+ // We need to look up the first parent
+ var parent *types.Header
+ if index == 0 {
+ parent = chain.GetHeader(headers[0].ParentHash, headers[0].Number.Uint64()-1)
+ } else if headers[index-1].Hash() == headers[index].ParentHash {
+ parent = headers[index-1]
+ }
+ // Ensure the validation is useful and execute it
+ var failure error
+ switch {
+ case chain.GetHeader(headers[index].Hash(), headers[index].Number.Uint64()-1) != nil:
+ outputs <- result{index: index, err: nil}
+ case parent == nil:
+ failure = ErrParentUnknown
+ outputs <- result{index: index, err: failure}
+ default:
+ failure = ethash.verifyHeader(chain, headers[index], parent, false, seals[index])
+ outputs <- result{index: index, err: failure}
+ }
+ // If a validation failure occurred, mark subsequent blocks invalid
+ if failure != nil {
+ number := headers[index].Number.Uint64()
+ if prev := atomic.LoadUint64(&badblock); prev == 0 || prev > number {
+ // This two step atomic op isn't thread-safe in that `badblock` might end
+ // up slightly higher than the block number of the first failure (if many
+ // workers try to write at the same time), but it's fine as we're mostly
+ // interested to avoid large useless work, we don't care about 1-2 extra
+ // runs. Doing "full thread safety" would involve mutexes, which would be
+ // a noticeable sync overhead on the fast spinning worker routines.
+ atomic.StoreUint64(&badblock, number)
+ }
+ }
+ }
+ }()
+ }
+ // Feed item indices to the workers until done, sorting and feeding the results to the caller
+ dones := make([]bool, len(headers))
+ errors := make([]error, len(headers))
+
+ abort := make(chan struct{})
+ returns := make(chan error, len(headers))
+
+ go func() {
+ defer close(inputs)
+
+ input, output := 0, 0
+ for i := 0; i < len(headers)*2; i++ {
+ var res result
+
+ // If there are tasks left, push to workers
+ if input < len(headers) {
+ select {
+ case inputs <- input:
+ input++
+ continue
+ case <-abort:
+ return
+ case res = <-outputs:
+ }
+ } else {
+ // Otherwise keep waiting for results
+ select {
+ case <-abort:
+ return
+ case res = <-outputs:
+ }
+ }
+ // A result arrived, save and propagate if next
+ dones[res.index], errors[res.index] = true, res.err
+ for output < len(headers) && dones[output] {
+ returns <- errors[output]
+ output++
+ }
+ }
+ }()
+ return abort, returns
+}
+
+// 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
+ }
+ // Gather the set of past uncles and ancestors
+ uncles, ancestors := set.New(), make(map[common.Hash]*types.Header)
+
+ number, parent := block.NumberU64()-1, block.ParentHash()
+ for i := 0; i < 7; i++ {
+ ancestor := chain.GetBlock(parent, number)
+ if ancestor == nil {
+ break
+ }
+ ancestors[ancestor.Hash()] = ancestor.Header()
+ for _, uncle := range ancestor.Uncles() {
+ uncles.Add(uncle.Hash())
+ }
+ parent, number = ancestor.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.Has(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, true); 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.ChainReader, header, parent *types.Header, uncle bool, seal bool) 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.Cmp(math.MaxBig256) > 0 {
+ return ErrLargeBlockTimestamp
+ }
+ } else {
+ if header.Time.Cmp(big.NewInt(time.Now().Unix())) > 0 {
+ return ErrFutureBlock
+ }
+ }
+ if header.Time.Cmp(parent.Time) <= 0 {
+ return ErrZeroBlockTime
+ }
+ // Verify the block's difficulty based in it's timestamp and parent's difficulty
+ expected := CalcDifficulty(chain.Config(), header.Time.Uint64(), parent.Time.Uint64(), parent.Number, parent.Difficulty)
+ if expected.Cmp(header.Difficulty) != 0 {
+ return fmt.Errorf("invalid difficulty: have %v, want %v", header.Difficulty, expected)
+ }
+ // Verify that the gas limit remains within allowed bounds
+ diff := new(big.Int).Set(parent.GasLimit)
+ diff = diff.Sub(diff, header.GasLimit)
+ diff.Abs(diff)
+
+ limit := new(big.Int).Set(parent.GasLimit)
+ limit = limit.Div(limit, params.GasLimitBoundDivisor)
+
+ if diff.Cmp(limit) >= 0 || header.GasLimit.Cmp(params.MinGasLimit) < 0 {
+ return fmt.Errorf("invalid gas limit: have %v, want %v += %v", header.GasLimit, parent.GasLimit, limit)
+ }
+ // 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 ErrInvalidNumber
+ }
+ // Verify the engine specific seal securing the block
+ if seal {
+ if err := ethash.VerifySeal(chain, header); err != nil {
+ return err
+ }
+ }
+ // If all checks passed, validate any special fields for hard forks
+ if err := misc.VerifyDAOHeaderExtraData(chain.Config(), header); err != nil {
+ return err
+ }
+ if err := misc.VerifyForkHashes(chain.Config(), header, uncle); 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.
+//
+// TODO (karalabe): Move the chain maker into this package and make this private!
+func CalcDifficulty(config *params.ChainConfig, time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
+ if config.IsHomestead(new(big.Int).Add(parentNumber, common.Big1)) {
+ return calcDifficultyHomestead(time, parentTime, parentNumber, parentDiff)
+ }
+ return calcDifficultyFrontier(time, parentTime, parentNumber, parentDiff)
+}
+
+// Some weird constants to avoid constant memory allocs for them.
+var (
+ expDiffPeriod = big.NewInt(100000)
+ big10 = big.NewInt(10)
+ bigMinus99 = big.NewInt(-99)
+)
+
+// 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, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
+ // https://github.com/ethereum/EIPs/blob/master/EIPS/eip-2.mediawiki
+ // 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(parentTime)
+
+ // 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(common.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(parentDiff, params.DifficultyBoundDivisor)
+ x.Mul(y, x)
+ x.Add(parentDiff, 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(parentNumber, common.Big1)
+ periodCount.Div(periodCount, expDiffPeriod)
+
+ // the exponential factor, commonly referred to as "the bomb"
+ // diff = diff + 2^(periodCount - 2)
+ if periodCount.Cmp(common.Big1) > 0 {
+ y.Sub(periodCount, common.Big2)
+ y.Exp(common.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, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
+ diff := new(big.Int)
+ adjust := new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor)
+ bigTime := new(big.Int)
+ bigParentTime := new(big.Int)
+
+ bigTime.SetUint64(time)
+ bigParentTime.SetUint64(parentTime)
+
+ if bigTime.Sub(bigTime, bigParentTime).Cmp(params.DurationLimit) < 0 {
+ diff.Add(parentDiff, adjust)
+ } else {
+ diff.Sub(parentDiff, adjust)
+ }
+ if diff.Cmp(params.MinimumDifficulty) < 0 {
+ diff.Set(params.MinimumDifficulty)
+ }
+
+ periodCount := new(big.Int).Add(parentNumber, common.Big1)
+ periodCount.Div(periodCount, expDiffPeriod)
+ if periodCount.Cmp(common.Big1) > 0 {
+ // diff = diff + 2^(periodCount - 2)
+ expDiff := periodCount.Sub(periodCount, common.Big2)
+ expDiff.Exp(common.Big2, expDiff, nil)
+ diff.Add(diff, expDiff)
+ diff = math.BigMax(diff, params.MinimumDifficulty)
+ }
+ return diff
+}
+
+// VerifySeal implements consensus.Engine, checking whether the given block satisfies
+// the PoW difficulty requirements.
+func (ethash *Ethash) VerifySeal(chain consensus.ChainReader, header *types.Header) error {
+ // If we're running a fake PoW, accept any seal as valid
+ if ethash.fakeMode {
+ time.Sleep(ethash.fakeDelay)
+ if ethash.fakeFail == header.Number.Uint64() {
+ return ErrInvalidPoW
+ }
+ return nil
+ }
+ // If we're running a shared PoW, delegate verification to it
+ if ethash.shared != nil {
+ return ethash.shared.VerifySeal(chain, header)
+ }
+ // Sanity check that the block number is below the lookup table size (60M blocks)
+ number := header.Number.Uint64()
+ if number/epochLength >= uint64(len(cacheSizes)) {
+ // Go < 1.7 cannot calculate new cache/dataset sizes (no fast prime check)
+ return ErrNonceOutOfRange
+ }
+ // Ensure that we have a valid difficulty for the block
+ if header.Difficulty.Sign() <= 0 {
+ return ErrInvalidDifficulty
+ }
+ // Recompute the digest and PoW value and verify against the header
+ cache := ethash.cache(number)
+
+ size := datasetSize(number)
+ if ethash.tester {
+ size = 32 * 1024
+ }
+ digest, result := hashimotoLight(size, cache, header.HashNoNonce().Bytes(), header.Nonce.Uint64())
+ if !bytes.Equal(header.MixDigest[:], digest) {
+ return ErrInvalidMixDigest
+ }
+ target := new(big.Int).Div(maxUint256, header.Difficulty)
+ if new(big.Int).SetBytes(result).Cmp(target) > 0 {
+ return ErrInvalidPoW
+ }
+ return nil
+}
+
+// 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.ChainReader, header *types.Header) error {
+ parent := chain.GetHeader(header.ParentHash, header.Number.Uint64()-1)
+ if parent == nil {
+ return ErrParentUnknown
+ }
+ header.Difficulty = CalcDifficulty(chain.Config(), header.Time.Uint64(),
+ parent.Time.Uint64(), parent.Number, parent.Difficulty)
+
+ return nil
+}
+
+// Finalize implements consensus.Engine, accumulating the block and uncle rewards,
+// setting the final state and assembling the block.
+func (ethash *Ethash) Finalize(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
+ // Accumulate any block and uncle rewards and commit the final state root
+ AccumulateRewards(state, header, uncles)
+ header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
+
+ // Header seems complete, assemble into a block and return
+ return types.NewBlock(header, txs, uncles, receipts), nil
+}
+
+// Some weird constants to avoid constant memory allocs for them.
+var (
+ big8 = big.NewInt(8)
+ big32 = big.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.
+//
+// TODO (karalabe): Move the chain maker into this package and make this private!
+func AccumulateRewards(state *state.StateDB, header *types.Header, uncles []*types.Header) {
+ reward := new(big.Int).Set(blockReward)
+ r := new(big.Int)
+ for _, uncle := range uncles {
+ r.Add(uncle.Number, big8)
+ r.Sub(r, header.Number)
+ r.Mul(r, blockReward)
+ r.Div(r, big8)
+ state.AddBalance(uncle.Coinbase, r)
+
+ r.Div(blockReward, big32)
+ reward.Add(reward, r)
+ }
+ state.AddBalance(header.Coinbase, reward)
+}
generated by cgit (git 2.34.1) at 2024-11-12 16:27:10 +0800