feat: Waku v2 bridge

Issue #12610

vendor/github.com/ethereum/go-ethereum/consensus/consensus.go

@@ -0,0 +1,130 @@
+// 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 consensus implements different Ethereum consensus engines.
+package consensus
+
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+// ChainHeaderReader defines a small collection of methods needed to access the local
+// blockchain during header verification.
+type ChainHeaderReader interface {
+	// Config retrieves the blockchain's chain configuration.
+	Config() *params.ChainConfig
+
+	// CurrentHeader retrieves the current header from the local chain.
+	CurrentHeader() *types.Header
+
+	// GetHeader retrieves a block header from the database by hash and number.
+	GetHeader(hash common.Hash, number uint64) *types.Header
+
+	// GetHeaderByNumber retrieves a block header from the database by number.
+	GetHeaderByNumber(number uint64) *types.Header
+
+	// GetHeaderByHash retrieves a block header from the database by its hash.
+	GetHeaderByHash(hash common.Hash) *types.Header
+
+	// GetTd retrieves the total difficulty from the database by hash and number.
+	GetTd(hash common.Hash, number uint64) *big.Int
+}
+
+// ChainReader defines a small collection of methods needed to access the local
+// blockchain during header and/or uncle verification.
+type ChainReader interface {
+	ChainHeaderReader
+
+	// GetBlock retrieves a block from the database by hash and number.
+	GetBlock(hash common.Hash, number uint64) *types.Block
+}
+
+// Engine is an algorithm agnostic consensus engine.
+type Engine interface {
+	// Author retrieves the Ethereum address of the account that minted the given
+	// block, which may be different from the header's coinbase if a consensus
+	// engine is based on signatures.
+	Author(header *types.Header) (common.Address, error)
+
+	// VerifyHeader checks whether a header conforms to the consensus rules of a
+	// given engine. Verifying the seal may be done optionally here, or explicitly
+	// via the VerifySeal method.
+	VerifyHeader(chain ChainHeaderReader, header *types.Header, seal bool) error
+
+	// 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 (the order is that of
+	// the input slice).
+	VerifyHeaders(chain ChainHeaderReader, headers []*types.Header, seals []bool) (chan<- struct{}, <-chan error)
+
+	// VerifyUncles verifies that the given block's uncles conform to the consensus
+	// rules of a given engine.
+	VerifyUncles(chain ChainReader, block *types.Block) error
+
+	// Prepare initializes the consensus fields of a block header according to the
+	// rules of a particular engine. The changes are executed inline.
+	Prepare(chain ChainHeaderReader, header *types.Header) error
+
+	// Finalize runs any post-transaction state modifications (e.g. block rewards)
+	// but does not assemble the block.
+	//
+	// Note: The block header and state database might be updated to reflect any
+	// consensus rules that happen at finalization (e.g. block rewards).
+	Finalize(chain ChainHeaderReader, header *types.Header, state *state.StateDB, txs []*types.Transaction,
+		uncles []*types.Header)
+
+	// FinalizeAndAssemble runs any post-transaction state modifications (e.g. block
+	// rewards) and assembles the final block.
+	//
+	// Note: The block header and state database might be updated to reflect any
+	// consensus rules that happen at finalization (e.g. block rewards).
+	FinalizeAndAssemble(chain ChainHeaderReader, header *types.Header, state *state.StateDB, txs []*types.Transaction,
+		uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error)
+
+	// Seal generates a new sealing request for the given input block and pushes
+	// the result into the given channel.
+	//
+	// Note, the method returns immediately and will send the result async. More
+	// than one result may also be returned depending on the consensus algorithm.
+	Seal(chain ChainHeaderReader, block *types.Block, results chan<- *types.Block, stop <-chan struct{}) error
+
+	// SealHash returns the hash of a block prior to it being sealed.
+	SealHash(header *types.Header) common.Hash
+
+	// CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
+	// that a new block should have.
+	CalcDifficulty(chain ChainHeaderReader, time uint64, parent *types.Header) *big.Int
+
+	// APIs returns the RPC APIs this consensus engine provides.
+	APIs(chain ChainHeaderReader) []rpc.API
+
+	// Close terminates any background threads maintained by the consensus engine.
+	Close() error
+}
+
+// PoW is a consensus engine based on proof-of-work.
+type PoW interface {
+	Engine
+
+	// Hashrate returns the current mining hashrate of a PoW consensus engine.
+	Hashrate() float64
+}

vendor/github.com/ethereum/go-ethereum/consensus/errors.go

@@ -0,0 +1,41 @@
+// 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 consensus
+
+import "errors"
+
+var (
+	// ErrUnknownAncestor is returned when validating a block requires an ancestor
+	// that is unknown.
+	ErrUnknownAncestor = errors.New("unknown ancestor")
+
+	// ErrPrunedAncestor is returned when validating a block requires an ancestor
+	// that is known, but the state of which is not available.
+	ErrPrunedAncestor = errors.New("pruned ancestor")
+
+	// ErrFutureBlock is returned when a block's timestamp is in the future according
+	// to the current node.
+	ErrFutureBlock = errors.New("block in the future")
+
+	// ErrInvalidNumber is returned if a block's number doesn't equal its parent's
+	// plus one.
+	ErrInvalidNumber = errors.New("invalid block number")
+
+	// ErrInvalidTerminalBlock is returned if a block is invalid wrt. the terminal
+	// total difficulty.
+	ErrInvalidTerminalBlock = errors.New("invalid terminal block")
+)

vendor/github.com/ethereum/go-ethereum/consensus/ethash/api.go

@@ -0,0 +1,113 @@
+// Copyright 2018 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"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/core/types"
+)
+
+var errEthashStopped = errors.New("ethash stopped")
+
+// API exposes ethash related methods for the RPC interface.
+type API struct {
+	ethash *Ethash
+}
+
+// GetWork returns a work package for external miner.
+//
+// The work package consists of 3 strings:
+//
+//	result[0] - 32 bytes hex encoded current block header pow-hash
+//	result[1] - 32 bytes hex encoded seed hash used for DAG
+//	result[2] - 32 bytes hex encoded boundary condition ("target"), 2^256/difficulty
+//	result[3] - hex encoded block number
+func (api *API) GetWork() ([4]string, error) {
+	if api.ethash.remote == nil {
+		return [4]string{}, errors.New("not supported")
+	}
+
+	var (
+		workCh = make(chan [4]string, 1)
+		errc   = make(chan error, 1)
+	)
+	select {
+	case api.ethash.remote.fetchWorkCh <- &sealWork{errc: errc, res: workCh}:
+	case <-api.ethash.remote.exitCh:
+		return [4]string{}, errEthashStopped
+	}
+	select {
+	case work := <-workCh:
+		return work, nil
+	case err := <-errc:
+		return [4]string{}, err
+	}
+}
+
+// SubmitWork can be used by external miner to submit their POW solution.
+// It returns an indication if the work was accepted.
+// Note either an invalid solution, a stale work a non-existent work will return false.
+func (api *API) SubmitWork(nonce types.BlockNonce, hash, digest common.Hash) bool {
+	if api.ethash.remote == nil {
+		return false
+	}
+
+	var errc = make(chan error, 1)
+	select {
+	case api.ethash.remote.submitWorkCh <- &mineResult{
+		nonce:     nonce,
+		mixDigest: digest,
+		hash:      hash,
+		errc:      errc,
+	}:
+	case <-api.ethash.remote.exitCh:
+		return false
+	}
+	err := <-errc
+	return err == nil
+}
+
+// SubmitHashrate can be used for remote miners to submit their hash rate.
+// This enables the node to report the combined hash rate of all miners
+// which submit work through this node.
+//
+// It accepts the miner hash rate and an identifier which must be unique
+// between nodes.
+func (api *API) SubmitHashrate(rate hexutil.Uint64, id common.Hash) bool {
+	if api.ethash.remote == nil {
+		return false
+	}
+
+	var done = make(chan struct{}, 1)
+	select {
+	case api.ethash.remote.submitRateCh <- &hashrate{done: done, rate: uint64(rate), id: id}:
+	case <-api.ethash.remote.exitCh:
+		return false
+	}
+
+	// Block until hash rate submitted successfully.
+	<-done
+	return true
+}
+
+// GetHashrate returns the current hashrate for local CPU miner and remote miner.
+func (api *API) GetHashrate() uint64 {
+	return uint64(api.ethash.Hashrate())
+}

vendor/github.com/ethereum/go-ethereum/consensus/ethash/consensus.go

@@ -0,0 +1,675 @@
+// 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"
+	"time"
+
+	mapset "github.com/deckarep/golang-set"
+	"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"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/trie"
+	"golang.org/x/crypto/sha3"
+)
+
+// Ethash proof-of-work protocol constants.
+var (
+	FrontierBlockReward           = big.NewInt(5e+18) // Block reward in wei for successfully mining a block
+	ByzantiumBlockReward          = big.NewInt(3e+18) // Block reward in wei for successfully mining a block upward from Byzantium
+	ConstantinopleBlockReward     = big.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
+
+	// 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))
+
+	// calcDifficultyConstantinople is the difficulty adjustment algorithm for Constantinople.
+	// 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, but with
+	// bomb offset 5M.
+	// Specification EIP-1234: https://eips.ethereum.org/EIPS/eip-1234
+	calcDifficultyConstantinople = makeDifficultyCalculator(big.NewInt(5000000))
+
+	// 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.
+	// 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")
+	errInvalidDifficulty = errors.New("non-positive difficulty")
+	errInvalidMixDigest  = errors.New("invalid mix digest")
+	errInvalidPoW        = errors.New("invalid proof-of-work")
+)
+
+// 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, seal bool) error {
+	// If we're running a full engine faking, accept any input as valid
+	if ethash.config.PowMode == ModeFullFake {
+		return nil
+	}
+	// 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, seal, 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, seals []bool) (chan<- struct{}, <-chan error) {
+	// If we're running a full engine faking, accept any input as valid
+	if ethash.config.PowMode == ModeFullFake || 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
+	}
+
+	// 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
+	var (
+		inputs  = make(chan int)
+		done    = make(chan int, workers)
+		errors  = make([]error, len(headers))
+		abort   = make(chan struct{})
+		unixNow = time.Now().Unix()
+	)
+	for i := 0; i < workers; i++ {
+		go func() {
+			for index := range inputs {
+				errors[index] = ethash.verifyHeaderWorker(chain, headers, seals, index, unixNow)
+				done <- index
+			}
+		}()
+	}
+
+	errorsOut := make(chan error, len(headers))
+	go func() {
+		defer close(inputs)
+		var (
+			in, out = 0, 0
+			checked = make([]bool, len(headers))
+			inputs  = inputs
+		)
+		for {
+			select {
+			case inputs <- in:
+				if in++; in == len(headers) {
+					// Reached end of headers. Stop sending to workers.
+					inputs = nil
+				}
+			case index := <-done:
+				for checked[index] = true; checked[out]; out++ {
+					errorsOut <- errors[out]
+					if out == len(headers)-1 {
+						return
+					}
+				}
+			case <-abort:
+				return
+			}
+		}
+	}()
+	return abort, errorsOut
+}
+
+func (ethash *Ethash) verifyHeaderWorker(chain consensus.ChainHeaderReader, headers []*types.Header, seals []bool, index int, unixNow int64) error {
+	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]
+	}
+	if parent == nil {
+		return consensus.ErrUnknownAncestor
+	}
+	return ethash.verifyHeader(chain, headers[index], parent, false, seals[index], unixNow)
+}
+
+// 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.config.PowMode == ModeFullFake {
+		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(), 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 {
+			// 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, 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, seal 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 := misc.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
+	}
+	// Verify the engine specific seal securing the block
+	if seal {
+		if err := ethash.verifySeal(chain, header, false); 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.
+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)
+)
+
+// 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 {
+	// 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)
+	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)
+
+		// 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)
+		}
+		// calculate a fake block number for the ice-age delay
+		// Specification: https://eips.ethereum.org/EIPS/eip-1234
+		fakeBlockNumber := new(big.Int)
+		if parent.Number.Cmp(bombDelayFromParent) >= 0 {
+			fakeBlockNumber = fakeBlockNumber.Sub(parent.Number, bombDelayFromParent)
+		}
+		// 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
+
+// verifySeal checks whether a block satisfies the PoW difficulty requirements,
+// either using the usual ethash cache for it, or alternatively using a full DAG
+// to make remote mining fast.
+func (ethash *Ethash) verifySeal(chain consensus.ChainHeaderReader, header *types.Header, fulldag bool) error {
+	// If we're running a fake PoW, accept any seal as valid
+	if ethash.config.PowMode == ModeFake || ethash.config.PowMode == ModeFullFake {
+		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, fulldag)
+	}
+	// Ensure that we have a valid difficulty for the block
+	if header.Difficulty.Sign() <= 0 {
+		return errInvalidDifficulty
+	}
+	// Recompute the digest and PoW values
+	number := header.Number.Uint64()
+
+	var (
+		digest []byte
+		result []byte
+	)
+	// If fast-but-heavy PoW verification was requested, use an ethash dataset
+	if fulldag {
+		dataset := ethash.dataset(number, true)
+		if dataset.generated() {
+			digest, result = hashimotoFull(dataset.dataset, ethash.SealHash(header).Bytes(), header.Nonce.Uint64())
+
+			// Datasets are unmapped in a finalizer. Ensure that the dataset stays alive
+			// until after the call to hashimotoFull so it's not unmapped while being used.
+			runtime.KeepAlive(dataset)
+		} else {
+			// Dataset not yet generated, don't hang, use a cache instead
+			fulldag = false
+		}
+	}
+	// If slow-but-light PoW verification was requested (or DAG not yet ready), use an ethash cache
+	if !fulldag {
+		cache := ethash.cache(number)
+
+		size := datasetSize(number)
+		if ethash.config.PowMode == ModeTest {
+			size = 32 * 1024
+		}
+		digest, result = hashimotoLight(size, cache.cache, ethash.SealHash(header).Bytes(), header.Nonce.Uint64())
+
+		// Caches are unmapped in a finalizer. Ensure that the cache stays alive
+		// until after the call to hashimotoLight so it's not unmapped while being used.
+		runtime.KeepAlive(cache)
+	}
+	// Verify the calculated values against the ones provided in the header
+	if !bytes.Equal(header.MixDigest[:], digest) {
+		return errInvalidMixDigest
+	}
+	target := new(big.Int).Div(two256, 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.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,
+// setting the final state on the header
+func (ethash *Ethash) Finalize(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header) {
+	// Accumulate any block and uncle rewards and commit the final state root
+	accumulateRewards(chain.Config(), state, header, uncles)
+	header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
+}
+
+// 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, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
+	// Finalize block
+	ethash.Finalize(chain, header, state, txs, uncles)
+
+	// Header seems complete, assemble into a block and return
+	return types.NewBlock(header, txs, 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)
+	}
+	rlp.Encode(hasher, enc)
+	hasher.Sum(hash[:0])
+	return hash
+}
+
+// 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.
+func accumulateRewards(config *params.ChainConfig, state *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(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)
+}

vendor/github.com/ethereum/go-ethereum/consensus/ethash/difficulty.go

@@ -0,0 +1,191 @@
+// Copyright 2020 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 (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/holiman/uint256"
+)
+
+const (
+	// frontierDurationLimit is for Frontier:
+	// The decision boundary on the blocktime duration used to determine
+	// whether difficulty should go up or down.
+	frontierDurationLimit = 13
+	// minimumDifficulty The minimum that the difficulty may ever be.
+	minimumDifficulty = 131072
+	// expDiffPeriod is the exponential difficulty period
+	expDiffPeriodUint = 100000
+	// difficultyBoundDivisorBitShift is the bound divisor of the difficulty (2048),
+	// This constant is the right-shifts to use for the division.
+	difficultyBoundDivisor = 11
+)
+
+// CalcDifficultyFrontierU256 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 CalcDifficultyFrontierU256(time uint64, parent *types.Header) *big.Int {
+	/*
+		Algorithm
+		block_diff = pdiff + pdiff / 2048 * (1 if time - ptime < 13 else -1) + int(2^((num // 100000) - 2))
+
+		Where:
+		- pdiff  = parent.difficulty
+		- ptime = parent.time
+		- time = block.timestamp
+		- num = block.number
+	*/
+
+	pDiff, _ := uint256.FromBig(parent.Difficulty) // pDiff: pdiff
+	adjust := pDiff.Clone()
+	adjust.Rsh(adjust, difficultyBoundDivisor) // adjust: pDiff / 2048
+
+	if time-parent.Time < frontierDurationLimit {
+		pDiff.Add(pDiff, adjust)
+	} else {
+		pDiff.Sub(pDiff, adjust)
+	}
+	if pDiff.LtUint64(minimumDifficulty) {
+		pDiff.SetUint64(minimumDifficulty)
+	}
+	// 'pdiff' now contains:
+	// pdiff + pdiff / 2048 * (1 if time - ptime < 13 else -1)
+
+	if periodCount := (parent.Number.Uint64() + 1) / expDiffPeriodUint; periodCount > 1 {
+		// diff = diff + 2^(periodCount - 2)
+		expDiff := adjust.SetOne()
+		expDiff.Lsh(expDiff, uint(periodCount-2)) // expdiff: 2 ^ (periodCount -2)
+		pDiff.Add(pDiff, expDiff)
+	}
+	return pDiff.ToBig()
+}
+
+// CalcDifficultyHomesteadU256 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 CalcDifficultyHomesteadU256(time uint64, parent *types.Header) *big.Int {
+	/*
+		https://github.com/ethereum/EIPs/blob/master/EIPS/eip-2.md
+		Algorithm:
+		block_diff = pdiff + pdiff / 2048 * max(1 - (time - ptime) / 10, -99) + 2 ^ int((num / 100000) - 2))
+
+		Our modification, to use unsigned ints:
+		block_diff = pdiff - pdiff / 2048 * max((time - ptime) / 10 - 1, 99) + 2 ^ int((num / 100000) - 2))
+
+		Where:
+		- pdiff  = parent.difficulty
+		- ptime = parent.time
+		- time = block.timestamp
+		- num = block.number
+	*/
+
+	pDiff, _ := uint256.FromBig(parent.Difficulty) // pDiff: pdiff
+	adjust := pDiff.Clone()
+	adjust.Rsh(adjust, difficultyBoundDivisor) // adjust: pDiff / 2048
+
+	x := (time - parent.Time) / 10 // (time - ptime) / 10)
+	var neg = true
+	if x == 0 {
+		x = 1
+		neg = false
+	} else if x >= 100 {
+		x = 99
+	} else {
+		x = x - 1
+	}
+	z := new(uint256.Int).SetUint64(x)
+	adjust.Mul(adjust, z) // adjust: (pdiff / 2048) * max((time - ptime) / 10 - 1, 99)
+	if neg {
+		pDiff.Sub(pDiff, adjust) // pdiff - pdiff / 2048 * max((time - ptime) / 10 - 1, 99)
+	} else {
+		pDiff.Add(pDiff, adjust) // pdiff + pdiff / 2048 * max((time - ptime) / 10 - 1, 99)
+	}
+	if pDiff.LtUint64(minimumDifficulty) {
+		pDiff.SetUint64(minimumDifficulty)
+	}
+	// for the exponential factor, a.k.a "the bomb"
+	// diff = diff + 2^(periodCount - 2)
+	if periodCount := (1 + parent.Number.Uint64()) / expDiffPeriodUint; periodCount > 1 {
+		expFactor := adjust.Lsh(adjust.SetOne(), uint(periodCount-2))
+		pDiff.Add(pDiff, expFactor)
+	}
+	return pDiff.ToBig()
+}
+
+// MakeDifficultyCalculatorU256 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 MakeDifficultyCalculatorU256(bombDelay *big.Int) func(time uint64, parent *types.Header) *big.Int {
+	// 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 := bombDelay.Uint64() - 1
+	return func(time uint64, parent *types.Header) *big.Int {
+		/*
+			https://github.com/ethereum/EIPs/issues/100
+			pDiff = parent.difficulty
+			BLOCK_DIFF_FACTOR = 9
+			a = pDiff + (pDiff // BLOCK_DIFF_FACTOR) * adj_factor
+			b = min(parent.difficulty, MIN_DIFF)
+			child_diff = max(a,b )
+		*/
+		x := (time - parent.Time) / 9 // (block_timestamp - parent_timestamp) // 9
+		c := uint64(1)                // if parent.unclehash == emptyUncleHashHash
+		if parent.UncleHash != types.EmptyUncleHash {
+			c = 2
+		}
+		xNeg := x >= c
+		if xNeg {
+			// x is now _negative_ adjustment factor
+			x = x - c // - ( (t-p)/p -( 2 or 1) )
+		} else {
+			x = c - x // (2 or 1) - (t-p)/9
+		}
+		if x > 99 {
+			x = 99 // max(x, 99)
+		}
+		// parent_diff + (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
+		y := new(uint256.Int)
+		y.SetFromBig(parent.Difficulty)    // y: p_diff
+		pDiff := y.Clone()                 // pdiff: p_diff
+		z := new(uint256.Int).SetUint64(x) //z : +-adj_factor (either pos or negative)
+		y.Rsh(y, difficultyBoundDivisor)   // y: p__diff / 2048
+		z.Mul(y, z)                        // z: (p_diff / 2048 ) * (+- adj_factor)
+
+		if xNeg {
+			y.Sub(pDiff, z) // y: parent_diff + parent_diff/2048 * adjustment_factor
+		} else {
+			y.Add(pDiff, z) // y: parent_diff + parent_diff/2048 * adjustment_factor
+		}
+		// minimum difficulty can ever be (before exponential factor)
+		if y.LtUint64(minimumDifficulty) {
+			y.SetUint64(minimumDifficulty)
+		}
+		// calculate a fake block number for the ice-age delay
+		// Specification: https://eips.ethereum.org/EIPS/eip-1234
+		var pNum = parent.Number.Uint64()
+		if pNum >= bombDelayFromParent {
+			if fakeBlockNumber := pNum - bombDelayFromParent; fakeBlockNumber >= 2*expDiffPeriodUint {
+				z.SetOne()
+				z.Lsh(z, uint(fakeBlockNumber/expDiffPeriodUint-2))
+				y.Add(z, y)
+			}
+		}
+		return y.ToBig()
+	}
+}

vendor/github.com/ethereum/go-ethereum/consensus/ethash/ethash.go

@@ -0,0 +1,697 @@
+// 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 implements the ethash proof-of-work consensus engine.
+package ethash
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"math/big"
+	"math/rand"
+	"os"
+	"path/filepath"
+	"reflect"
+	"runtime"
+	"strconv"
+	"sync"
+	"sync/atomic"
+	"time"
+	"unsafe"
+
+	"github.com/edsrzf/mmap-go"
+	"github.com/ethereum/go-ethereum/consensus"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/metrics"
+	"github.com/ethereum/go-ethereum/rpc"
+	"github.com/hashicorp/golang-lru/simplelru"
+)
+
+var ErrInvalidDumpMagic = errors.New("invalid dump magic")
+
+var (
+	// two256 is a big integer representing 2^256
+	two256 = new(big.Int).Exp(big.NewInt(2), big.NewInt(256), big.NewInt(0))
+
+	// sharedEthash is a full instance that can be shared between multiple users.
+	sharedEthash *Ethash
+
+	// algorithmRevision is the data structure version used for file naming.
+	algorithmRevision = 23
+
+	// dumpMagic is a dataset dump header to sanity check a data dump.
+	dumpMagic = []uint32{0xbaddcafe, 0xfee1dead}
+)
+
+func init() {
+	sharedConfig := Config{
+		PowMode:       ModeNormal,
+		CachesInMem:   3,
+		DatasetsInMem: 1,
+	}
+	sharedEthash = New(sharedConfig, nil, false)
+}
+
+// isLittleEndian returns whether the local system is running in little or big
+// endian byte order.
+func isLittleEndian() bool {
+	n := uint32(0x01020304)
+	return *(*byte)(unsafe.Pointer(&n)) == 0x04
+}
+
+// memoryMap tries to memory map a file of uint32s for read only access.
+func memoryMap(path string, lock bool) (*os.File, mmap.MMap, []uint32, error) {
+	file, err := os.OpenFile(path, os.O_RDONLY, 0644)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	mem, buffer, err := memoryMapFile(file, false)
+	if err != nil {
+		file.Close()
+		return nil, nil, nil, err
+	}
+	for i, magic := range dumpMagic {
+		if buffer[i] != magic {
+			mem.Unmap()
+			file.Close()
+			return nil, nil, nil, ErrInvalidDumpMagic
+		}
+	}
+	if lock {
+		if err := mem.Lock(); err != nil {
+			mem.Unmap()
+			file.Close()
+			return nil, nil, nil, err
+		}
+	}
+	return file, mem, buffer[len(dumpMagic):], err
+}
+
+// memoryMapFile tries to memory map an already opened file descriptor.
+func memoryMapFile(file *os.File, write bool) (mmap.MMap, []uint32, error) {
+	// Try to memory map the file
+	flag := mmap.RDONLY
+	if write {
+		flag = mmap.RDWR
+	}
+	mem, err := mmap.Map(file, flag, 0)
+	if err != nil {
+		return nil, nil, err
+	}
+	// The file is now memory-mapped. Create a []uint32 view of the file.
+	var view []uint32
+	header := (*reflect.SliceHeader)(unsafe.Pointer(&view))
+	header.Data = (*reflect.SliceHeader)(unsafe.Pointer(&mem)).Data
+	header.Cap = len(mem) / 4
+	header.Len = header.Cap
+	return mem, view, nil
+}
+
+// memoryMapAndGenerate tries to memory map a temporary file of uint32s for write
+// access, fill it with the data from a generator and then move it into the final
+// path requested.
+func memoryMapAndGenerate(path string, size uint64, lock bool, generator func(buffer []uint32)) (*os.File, mmap.MMap, []uint32, error) {
+	// Ensure the data folder exists
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		return nil, nil, nil, err
+	}
+	// Create a huge temporary empty file to fill with data
+	temp := path + "." + strconv.Itoa(rand.Int())
+
+	dump, err := os.Create(temp)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	if err = ensureSize(dump, int64(len(dumpMagic))*4+int64(size)); err != nil {
+		dump.Close()
+		os.Remove(temp)
+		return nil, nil, nil, err
+	}
+	// Memory map the file for writing and fill it with the generator
+	mem, buffer, err := memoryMapFile(dump, true)
+	if err != nil {
+		dump.Close()
+		os.Remove(temp)
+		return nil, nil, nil, err
+	}
+	copy(buffer, dumpMagic)
+
+	data := buffer[len(dumpMagic):]
+	generator(data)
+
+	if err := mem.Unmap(); err != nil {
+		return nil, nil, nil, err
+	}
+	if err := dump.Close(); err != nil {
+		return nil, nil, nil, err
+	}
+	if err := os.Rename(temp, path); err != nil {
+		return nil, nil, nil, err
+	}
+	return memoryMap(path, lock)
+}
+
+// lru tracks caches or datasets by their last use time, keeping at most N of them.
+type lru struct {
+	what string
+	new  func(epoch uint64) interface{}
+	mu   sync.Mutex
+	// Items are kept in a LRU cache, but there is a special case:
+	// We always keep an item for (highest seen epoch) + 1 as the 'future item'.
+	cache      *simplelru.LRU
+	future     uint64
+	futureItem interface{}
+}
+
+// newlru create a new least-recently-used cache for either the verification caches
+// or the mining datasets.
+func newlru(what string, maxItems int, new func(epoch uint64) interface{}) *lru {
+	if maxItems <= 0 {
+		maxItems = 1
+	}
+	cache, _ := simplelru.NewLRU(maxItems, func(key, value interface{}) {
+		log.Trace("Evicted ethash "+what, "epoch", key)
+	})
+	return &lru{what: what, new: new, cache: cache}
+}
+
+// get retrieves or creates an item for the given epoch. The first return value is always
+// non-nil. The second return value is non-nil if lru thinks that an item will be useful in
+// the near future.
+func (lru *lru) get(epoch uint64) (item, future interface{}) {
+	lru.mu.Lock()
+	defer lru.mu.Unlock()
+
+	// Get or create the item for the requested epoch.
+	item, ok := lru.cache.Get(epoch)
+	if !ok {
+		if lru.future > 0 && lru.future == epoch {
+			item = lru.futureItem
+		} else {
+			log.Trace("Requiring new ethash "+lru.what, "epoch", epoch)
+			item = lru.new(epoch)
+		}
+		lru.cache.Add(epoch, item)
+	}
+	// Update the 'future item' if epoch is larger than previously seen.
+	if epoch < maxEpoch-1 && lru.future < epoch+1 {
+		log.Trace("Requiring new future ethash "+lru.what, "epoch", epoch+1)
+		future = lru.new(epoch + 1)
+		lru.future = epoch + 1
+		lru.futureItem = future
+	}
+	return item, future
+}
+
+// cache wraps an ethash cache with some metadata to allow easier concurrent use.
+type cache struct {
+	epoch uint64    // Epoch for which this cache is relevant
+	dump  *os.File  // File descriptor of the memory mapped cache
+	mmap  mmap.MMap // Memory map itself to unmap before releasing
+	cache []uint32  // The actual cache data content (may be memory mapped)
+	once  sync.Once // Ensures the cache is generated only once
+}
+
+// newCache creates a new ethash verification cache and returns it as a plain Go
+// interface to be usable in an LRU cache.
+func newCache(epoch uint64) interface{} {
+	return &cache{epoch: epoch}
+}
+
+// generate ensures that the cache content is generated before use.
+func (c *cache) generate(dir string, limit int, lock bool, test bool) {
+	c.once.Do(func() {
+		size := cacheSize(c.epoch*epochLength + 1)
+		seed := seedHash(c.epoch*epochLength + 1)
+		if test {
+			size = 1024
+		}
+		// If we don't store anything on disk, generate and return.
+		if dir == "" {
+			c.cache = make([]uint32, size/4)
+			generateCache(c.cache, c.epoch, seed)
+			return
+		}
+		// Disk storage is needed, this will get fancy
+		var endian string
+		if !isLittleEndian() {
+			endian = ".be"
+		}
+		path := filepath.Join(dir, fmt.Sprintf("cache-R%d-%x%s", algorithmRevision, seed[:8], endian))
+		logger := log.New("epoch", c.epoch)
+
+		// We're about to mmap the file, ensure that the mapping is cleaned up when the
+		// cache becomes unused.
+		runtime.SetFinalizer(c, (*cache).finalizer)
+
+		// Try to load the file from disk and memory map it
+		var err error
+		c.dump, c.mmap, c.cache, err = memoryMap(path, lock)
+		if err == nil {
+			logger.Debug("Loaded old ethash cache from disk")
+			return
+		}
+		logger.Debug("Failed to load old ethash cache", "err", err)
+
+		// No previous cache available, create a new cache file to fill
+		c.dump, c.mmap, c.cache, err = memoryMapAndGenerate(path, size, lock, func(buffer []uint32) { generateCache(buffer, c.epoch, seed) })
+		if err != nil {
+			logger.Error("Failed to generate mapped ethash cache", "err", err)
+
+			c.cache = make([]uint32, size/4)
+			generateCache(c.cache, c.epoch, seed)
+		}
+		// Iterate over all previous instances and delete old ones
+		for ep := int(c.epoch) - limit; ep >= 0; ep-- {
+			seed := seedHash(uint64(ep)*epochLength + 1)
+			path := filepath.Join(dir, fmt.Sprintf("cache-R%d-%x%s*", algorithmRevision, seed[:8], endian))
+			files, _ := filepath.Glob(path) // find also the temp files that are generated.
+			for _, file := range files {
+				os.Remove(file)
+			}
+		}
+	})
+}
+
+// finalizer unmaps the memory and closes the file.
+func (c *cache) finalizer() {
+	if c.mmap != nil {
+		c.mmap.Unmap()
+		c.dump.Close()
+		c.mmap, c.dump = nil, nil
+	}
+}
+
+// dataset wraps an ethash dataset with some metadata to allow easier concurrent use.
+type dataset struct {
+	epoch   uint64    // Epoch for which this cache is relevant
+	dump    *os.File  // File descriptor of the memory mapped cache
+	mmap    mmap.MMap // Memory map itself to unmap before releasing
+	dataset []uint32  // The actual cache data content
+	once    sync.Once // Ensures the cache is generated only once
+	done    uint32    // Atomic flag to determine generation status
+}
+
+// newDataset creates a new ethash mining dataset and returns it as a plain Go
+// interface to be usable in an LRU cache.
+func newDataset(epoch uint64) interface{} {
+	return &dataset{epoch: epoch}
+}
+
+// generate ensures that the dataset content is generated before use.
+func (d *dataset) generate(dir string, limit int, lock bool, test bool) {
+	d.once.Do(func() {
+		// Mark the dataset generated after we're done. This is needed for remote
+		defer atomic.StoreUint32(&d.done, 1)
+
+		csize := cacheSize(d.epoch*epochLength + 1)
+		dsize := datasetSize(d.epoch*epochLength + 1)
+		seed := seedHash(d.epoch*epochLength + 1)
+		if test {
+			csize = 1024
+			dsize = 32 * 1024
+		}
+		// If we don't store anything on disk, generate and return
+		if dir == "" {
+			cache := make([]uint32, csize/4)
+			generateCache(cache, d.epoch, seed)
+
+			d.dataset = make([]uint32, dsize/4)
+			generateDataset(d.dataset, d.epoch, cache)
+
+			return
+		}
+		// Disk storage is needed, this will get fancy
+		var endian string
+		if !isLittleEndian() {
+			endian = ".be"
+		}
+		path := filepath.Join(dir, fmt.Sprintf("full-R%d-%x%s", algorithmRevision, seed[:8], endian))
+		logger := log.New("epoch", d.epoch)
+
+		// We're about to mmap the file, ensure that the mapping is cleaned up when the
+		// cache becomes unused.
+		runtime.SetFinalizer(d, (*dataset).finalizer)
+
+		// Try to load the file from disk and memory map it
+		var err error
+		d.dump, d.mmap, d.dataset, err = memoryMap(path, lock)
+		if err == nil {
+			logger.Debug("Loaded old ethash dataset from disk")
+			return
+		}
+		logger.Debug("Failed to load old ethash dataset", "err", err)
+
+		// No previous dataset available, create a new dataset file to fill
+		cache := make([]uint32, csize/4)
+		generateCache(cache, d.epoch, seed)
+
+		d.dump, d.mmap, d.dataset, err = memoryMapAndGenerate(path, dsize, lock, func(buffer []uint32) { generateDataset(buffer, d.epoch, cache) })
+		if err != nil {
+			logger.Error("Failed to generate mapped ethash dataset", "err", err)
+
+			d.dataset = make([]uint32, dsize/4)
+			generateDataset(d.dataset, d.epoch, cache)
+		}
+		// Iterate over all previous instances and delete old ones
+		for ep := int(d.epoch) - limit; ep >= 0; ep-- {
+			seed := seedHash(uint64(ep)*epochLength + 1)
+			path := filepath.Join(dir, fmt.Sprintf("full-R%d-%x%s", algorithmRevision, seed[:8], endian))
+			os.Remove(path)
+		}
+	})
+}
+
+// generated returns whether this particular dataset finished generating already
+// or not (it may not have been started at all). This is useful for remote miners
+// to default to verification caches instead of blocking on DAG generations.
+func (d *dataset) generated() bool {
+	return atomic.LoadUint32(&d.done) == 1
+}
+
+// finalizer closes any file handlers and memory maps open.
+func (d *dataset) finalizer() {
+	if d.mmap != nil {
+		d.mmap.Unmap()
+		d.dump.Close()
+		d.mmap, d.dump = nil, nil
+	}
+}
+
+// MakeCache generates a new ethash cache and optionally stores it to disk.
+func MakeCache(block uint64, dir string) {
+	c := cache{epoch: block / epochLength}
+	c.generate(dir, math.MaxInt32, false, false)
+}
+
+// MakeDataset generates a new ethash dataset and optionally stores it to disk.
+func MakeDataset(block uint64, dir string) {
+	d := dataset{epoch: block / epochLength}
+	d.generate(dir, math.MaxInt32, false, false)
+}
+
+// Mode defines the type and amount of PoW verification an ethash engine makes.
+type Mode uint
+
+const (
+	ModeNormal Mode = iota
+	ModeShared
+	ModeTest
+	ModeFake
+	ModeFullFake
+)
+
+// Config are the configuration parameters of the ethash.
+type Config struct {
+	CacheDir         string
+	CachesInMem      int
+	CachesOnDisk     int
+	CachesLockMmap   bool
+	DatasetDir       string
+	DatasetsInMem    int
+	DatasetsOnDisk   int
+	DatasetsLockMmap bool
+	PowMode          Mode
+
+	// When set, notifications sent by the remote sealer will
+	// be block header JSON objects instead of work package arrays.
+	NotifyFull bool
+
+	Log log.Logger `toml:"-"`
+}
+
+// Ethash is a consensus engine based on proof-of-work implementing the ethash
+// algorithm.
+type Ethash struct {
+	config Config
+
+	caches   *lru // In memory caches to avoid regenerating too often
+	datasets *lru // In memory datasets to avoid regenerating too often
+
+	// Mining related fields
+	rand     *rand.Rand    // Properly seeded random source for nonces
+	threads  int           // Number of threads to mine on if mining
+	update   chan struct{} // Notification channel to update mining parameters
+	hashrate metrics.Meter // Meter tracking the average hashrate
+	remote   *remoteSealer
+
+	// The fields below are hooks for testing
+	shared    *Ethash       // Shared PoW verifier to avoid cache regeneration
+	fakeFail  uint64        // Block number which fails PoW check even in fake mode
+	fakeDelay time.Duration // Time delay to sleep for before returning from verify
+
+	lock      sync.Mutex // Ensures thread safety for the in-memory caches and mining fields
+	closeOnce sync.Once  // Ensures exit channel will not be closed twice.
+}
+
+// New creates a full sized ethash PoW scheme and starts a background thread for
+// remote mining, also optionally notifying a batch of remote services of new work
+// packages.
+func New(config Config, notify []string, noverify bool) *Ethash {
+	if config.Log == nil {
+		config.Log = log.Root()
+	}
+	if config.CachesInMem <= 0 {
+		config.Log.Warn("One ethash cache must always be in memory", "requested", config.CachesInMem)
+		config.CachesInMem = 1
+	}
+	if config.CacheDir != "" && config.CachesOnDisk > 0 {
+		config.Log.Info("Disk storage enabled for ethash caches", "dir", config.CacheDir, "count", config.CachesOnDisk)
+	}
+	if config.DatasetDir != "" && config.DatasetsOnDisk > 0 {
+		config.Log.Info("Disk storage enabled for ethash DAGs", "dir", config.DatasetDir, "count", config.DatasetsOnDisk)
+	}
+	ethash := &Ethash{
+		config:   config,
+		caches:   newlru("cache", config.CachesInMem, newCache),
+		datasets: newlru("dataset", config.DatasetsInMem, newDataset),
+		update:   make(chan struct{}),
+		hashrate: metrics.NewMeterForced(),
+	}
+	if config.PowMode == ModeShared {
+		ethash.shared = sharedEthash
+	}
+	ethash.remote = startRemoteSealer(ethash, notify, noverify)
+	return ethash
+}
+
+// NewTester creates a small sized ethash PoW scheme useful only for testing
+// purposes.
+func NewTester(notify []string, noverify bool) *Ethash {
+	return New(Config{PowMode: ModeTest}, notify, noverify)
+}
+
+// NewFaker creates a ethash consensus engine with a fake PoW scheme that accepts
+// all blocks' seal as valid, though they still have to conform to the Ethereum
+// consensus rules.
+func NewFaker() *Ethash {
+	return &Ethash{
+		config: Config{
+			PowMode: ModeFake,
+			Log:     log.Root(),
+		},
+	}
+}
+
+// NewFakeFailer creates a ethash consensus engine with a fake PoW scheme that
+// accepts all blocks as valid apart from the single one specified, though they
+// still have to conform to the Ethereum consensus rules.
+func NewFakeFailer(fail uint64) *Ethash {
+	return &Ethash{
+		config: Config{
+			PowMode: ModeFake,
+			Log:     log.Root(),
+		},
+		fakeFail: fail,
+	}
+}
+
+// NewFakeDelayer creates a ethash consensus engine with a fake PoW scheme that
+// accepts all blocks as valid, but delays verifications by some time, though
+// they still have to conform to the Ethereum consensus rules.
+func NewFakeDelayer(delay time.Duration) *Ethash {
+	return &Ethash{
+		config: Config{
+			PowMode: ModeFake,
+			Log:     log.Root(),
+		},
+		fakeDelay: delay,
+	}
+}
+
+// NewFullFaker creates an ethash consensus engine with a full fake scheme that
+// accepts all blocks as valid, without checking any consensus rules whatsoever.
+func NewFullFaker() *Ethash {
+	return &Ethash{
+		config: Config{
+			PowMode: ModeFullFake,
+			Log:     log.Root(),
+		},
+	}
+}
+
+// NewShared creates a full sized ethash PoW shared between all requesters running
+// in the same process.
+func NewShared() *Ethash {
+	return &Ethash{shared: sharedEthash}
+}
+
+// Close closes the exit channel to notify all backend threads exiting.
+func (ethash *Ethash) Close() error {
+	return ethash.StopRemoteSealer()
+}
+
+// StopRemoteSealer stops the remote sealer
+func (ethash *Ethash) StopRemoteSealer() error {
+	ethash.closeOnce.Do(func() {
+		// Short circuit if the exit channel is not allocated.
+		if ethash.remote == nil {
+			return
+		}
+		close(ethash.remote.requestExit)
+		<-ethash.remote.exitCh
+	})
+	return nil
+}
+
+// cache tries to retrieve a verification cache for the specified block number
+// by first checking against a list of in-memory caches, then against caches
+// stored on disk, and finally generating one if none can be found.
+func (ethash *Ethash) cache(block uint64) *cache {
+	epoch := block / epochLength
+	currentI, futureI := ethash.caches.get(epoch)
+	current := currentI.(*cache)
+
+	// Wait for generation finish.
+	current.generate(ethash.config.CacheDir, ethash.config.CachesOnDisk, ethash.config.CachesLockMmap, ethash.config.PowMode == ModeTest)
+
+	// If we need a new future cache, now's a good time to regenerate it.
+	if futureI != nil {
+		future := futureI.(*cache)
+		go future.generate(ethash.config.CacheDir, ethash.config.CachesOnDisk, ethash.config.CachesLockMmap, ethash.config.PowMode == ModeTest)
+	}
+	return current
+}
+
+// dataset tries to retrieve a mining dataset for the specified block number
+// by first checking against a list of in-memory datasets, then against DAGs
+// stored on disk, and finally generating one if none can be found.
+//
+// If async is specified, not only the future but the current DAG is also
+// generates on a background thread.
+func (ethash *Ethash) dataset(block uint64, async bool) *dataset {
+	// Retrieve the requested ethash dataset
+	epoch := block / epochLength
+	currentI, futureI := ethash.datasets.get(epoch)
+	current := currentI.(*dataset)
+
+	// If async is specified, generate everything in a background thread
+	if async && !current.generated() {
+		go func() {
+			current.generate(ethash.config.DatasetDir, ethash.config.DatasetsOnDisk, ethash.config.DatasetsLockMmap, ethash.config.PowMode == ModeTest)
+
+			if futureI != nil {
+				future := futureI.(*dataset)
+				future.generate(ethash.config.DatasetDir, ethash.config.DatasetsOnDisk, ethash.config.DatasetsLockMmap, ethash.config.PowMode == ModeTest)
+			}
+		}()
+	} else {
+		// Either blocking generation was requested, or already done
+		current.generate(ethash.config.DatasetDir, ethash.config.DatasetsOnDisk, ethash.config.DatasetsLockMmap, ethash.config.PowMode == ModeTest)
+
+		if futureI != nil {
+			future := futureI.(*dataset)
+			go future.generate(ethash.config.DatasetDir, ethash.config.DatasetsOnDisk, ethash.config.DatasetsLockMmap, ethash.config.PowMode == ModeTest)
+		}
+	}
+	return current
+}
+
+// Threads returns the number of mining threads currently enabled. This doesn't
+// necessarily mean that mining is running!
+func (ethash *Ethash) Threads() int {
+	ethash.lock.Lock()
+	defer ethash.lock.Unlock()
+
+	return ethash.threads
+}
+
+// SetThreads updates the number of mining threads currently enabled. Calling
+// this method does not start mining, only sets the thread count. If zero is
+// specified, the miner will use all cores of the machine. Setting a thread
+// count below zero is allowed and will cause the miner to idle, without any
+// work being done.
+func (ethash *Ethash) SetThreads(threads int) {
+	ethash.lock.Lock()
+	defer ethash.lock.Unlock()
+
+	// If we're running a shared PoW, set the thread count on that instead
+	if ethash.shared != nil {
+		ethash.shared.SetThreads(threads)
+		return
+	}
+	// Update the threads and ping any running seal to pull in any changes
+	ethash.threads = threads
+	select {
+	case ethash.update <- struct{}{}:
+	default:
+	}
+}
+
+// Hashrate implements PoW, returning the measured rate of the search invocations
+// per second over the last minute.
+// Note the returned hashrate includes local hashrate, but also includes the total
+// hashrate of all remote miner.
+func (ethash *Ethash) Hashrate() float64 {
+	// Short circuit if we are run the ethash in normal/test mode.
+	if ethash.config.PowMode != ModeNormal && ethash.config.PowMode != ModeTest {
+		return ethash.hashrate.Rate1()
+	}
+	var res = make(chan uint64, 1)
+
+	select {
+	case ethash.remote.fetchRateCh <- res:
+	case <-ethash.remote.exitCh:
+		// Return local hashrate only if ethash is stopped.
+		return ethash.hashrate.Rate1()
+	}
+
+	// Gather total submitted hash rate of remote sealers.
+	return ethash.hashrate.Rate1() + float64(<-res)
+}
+
+// APIs implements consensus.Engine, returning the user facing RPC APIs.
+func (ethash *Ethash) APIs(chain consensus.ChainHeaderReader) []rpc.API {
+	// In order to ensure backward compatibility, we exposes ethash RPC APIs
+	// to both eth and ethash namespaces.
+	return []rpc.API{
+		{
+			Namespace: "eth",
+			Service:   &API{ethash},
+		},
+		{
+			Namespace: "ethash",
+			Service:   &API{ethash},
+		},
+	}
+}
+
+// SeedHash is the seed to use for generating a verification cache and the mining
+// dataset.
+func SeedHash(block uint64) []byte {
+	return seedHash(block)
+}

vendor/github.com/ethereum/go-ethereum/consensus/ethash/mmap_help_linux.go

@@ -0,0 +1,35 @@
+// Copyright 2021 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/>.
+
+//go:build linux
+// +build linux
+
+package ethash
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+// ensureSize expands the file to the given size. This is to prevent runtime
+// errors later on, if the underlying file expands beyond the disk capacity,
+// even though it ostensibly is already expanded, but due to being sparse
+// does not actually occupy the full declared size on disk.
+func ensureSize(f *os.File, size int64) error {
+	// Docs: https://www.man7.org/linux/man-pages/man2/fallocate.2.html
+	return unix.Fallocate(int(f.Fd()), 0, 0, size)
+}

vendor/github.com/ethereum/go-ethereum/consensus/ethash/mmap_help_other.go

@@ -0,0 +1,36 @@
+// Copyright 2021 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/>.
+
+//go:build !linux
+// +build !linux
+
+package ethash
+
+import (
+	"os"
+)
+
+// ensureSize expands the file to the given size. This is to prevent runtime
+// errors later on, if the underlying file expands beyond the disk capacity,
+// even though it ostensibly is already expanded, but due to being sparse
+// does not actually occupy the full declared size on disk.
+func ensureSize(f *os.File, size int64) error {
+	// On systems which do not support fallocate, we merely truncate it.
+	// More robust alternatives  would be to
+	// - Use posix_fallocate, or
+	// - explicitly fill the file with zeroes.
+	return f.Truncate(size)
+}

vendor/github.com/ethereum/go-ethereum/consensus/ethash/sealer.go

@@ -0,0 +1,451 @@
+// 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"
+	"context"
+	crand "crypto/rand"
+	"encoding/json"
+	"errors"
+	"math"
+	"math/big"
+	"math/rand"
+	"net/http"
+	"runtime"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/consensus"
+	"github.com/ethereum/go-ethereum/core/types"
+)
+
+const (
+	// staleThreshold is the maximum depth of the acceptable stale but valid ethash solution.
+	staleThreshold = 7
+)
+
+var (
+	errNoMiningWork      = errors.New("no mining work available yet")
+	errInvalidSealResult = errors.New("invalid or stale proof-of-work solution")
+)
+
+// Seal implements consensus.Engine, attempting to find a nonce that satisfies
+// the block's difficulty requirements.
+func (ethash *Ethash) Seal(chain consensus.ChainHeaderReader, block *types.Block, results chan<- *types.Block, stop <-chan struct{}) error {
+	// If we're running a fake PoW, simply return a 0 nonce immediately
+	if ethash.config.PowMode == ModeFake || ethash.config.PowMode == ModeFullFake {
+		header := block.Header()
+		header.Nonce, header.MixDigest = types.BlockNonce{}, common.Hash{}
+		select {
+		case results <- block.WithSeal(header):
+		default:
+			ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "fake", "sealhash", ethash.SealHash(block.Header()))
+		}
+		return nil
+	}
+	// If we're running a shared PoW, delegate sealing to it
+	if ethash.shared != nil {
+		return ethash.shared.Seal(chain, block, results, stop)
+	}
+	// Create a runner and the multiple search threads it directs
+	abort := make(chan struct{})
+
+	ethash.lock.Lock()
+	threads := ethash.threads
+	if ethash.rand == nil {
+		seed, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
+		if err != nil {
+			ethash.lock.Unlock()
+			return err
+		}
+		ethash.rand = rand.New(rand.NewSource(seed.Int64()))
+	}
+	ethash.lock.Unlock()
+	if threads == 0 {
+		threads = runtime.NumCPU()
+	}
+	if threads < 0 {
+		threads = 0 // Allows disabling local mining without extra logic around local/remote
+	}
+	// Push new work to remote sealer
+	if ethash.remote != nil {
+		ethash.remote.workCh <- &sealTask{block: block, results: results}
+	}
+	var (
+		pend   sync.WaitGroup
+		locals = make(chan *types.Block)
+	)
+	for i := 0; i < threads; i++ {
+		pend.Add(1)
+		go func(id int, nonce uint64) {
+			defer pend.Done()
+			ethash.mine(block, id, nonce, abort, locals)
+		}(i, uint64(ethash.rand.Int63()))
+	}
+	// Wait until sealing is terminated or a nonce is found
+	go func() {
+		var result *types.Block
+		select {
+		case <-stop:
+			// Outside abort, stop all miner threads
+			close(abort)
+		case result = <-locals:
+			// One of the threads found a block, abort all others
+			select {
+			case results <- result:
+			default:
+				ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "local", "sealhash", ethash.SealHash(block.Header()))
+			}
+			close(abort)
+		case <-ethash.update:
+			// Thread count was changed on user request, restart
+			close(abort)
+			if err := ethash.Seal(chain, block, results, stop); err != nil {
+				ethash.config.Log.Error("Failed to restart sealing after update", "err", err)
+			}
+		}
+		// Wait for all miners to terminate and return the block
+		pend.Wait()
+	}()
+	return nil
+}
+
+// mine is the actual proof-of-work miner that searches for a nonce starting from
+// seed that results in correct final block difficulty.
+func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan struct{}, found chan *types.Block) {
+	// Extract some data from the header
+	var (
+		header  = block.Header()
+		hash    = ethash.SealHash(header).Bytes()
+		target  = new(big.Int).Div(two256, header.Difficulty)
+		number  = header.Number.Uint64()
+		dataset = ethash.dataset(number, false)
+	)
+	// Start generating random nonces until we abort or find a good one
+	var (
+		attempts  = int64(0)
+		nonce     = seed
+		powBuffer = new(big.Int)
+	)
+	logger := ethash.config.Log.New("miner", id)
+	logger.Trace("Started ethash search for new nonces", "seed", seed)
+search:
+	for {
+		select {
+		case <-abort:
+			// Mining terminated, update stats and abort
+			logger.Trace("Ethash nonce search aborted", "attempts", nonce-seed)
+			ethash.hashrate.Mark(attempts)
+			break search
+
+		default:
+			// We don't have to update hash rate on every nonce, so update after after 2^X nonces
+			attempts++
+			if (attempts % (1 << 15)) == 0 {
+				ethash.hashrate.Mark(attempts)
+				attempts = 0
+			}
+			// Compute the PoW value of this nonce
+			digest, result := hashimotoFull(dataset.dataset, hash, nonce)
+			if powBuffer.SetBytes(result).Cmp(target) <= 0 {
+				// Correct nonce found, create a new header with it
+				header = types.CopyHeader(header)
+				header.Nonce = types.EncodeNonce(nonce)
+				header.MixDigest = common.BytesToHash(digest)
+
+				// Seal and return a block (if still needed)
+				select {
+				case found <- block.WithSeal(header):
+					logger.Trace("Ethash nonce found and reported", "attempts", nonce-seed, "nonce", nonce)
+				case <-abort:
+					logger.Trace("Ethash nonce found but discarded", "attempts", nonce-seed, "nonce", nonce)
+				}
+				break search
+			}
+			nonce++
+		}
+	}
+	// Datasets are unmapped in a finalizer. Ensure that the dataset stays live
+	// during sealing so it's not unmapped while being read.
+	runtime.KeepAlive(dataset)
+}
+
+// This is the timeout for HTTP requests to notify external miners.
+const remoteSealerTimeout = 1 * time.Second
+
+type remoteSealer struct {
+	works        map[common.Hash]*types.Block
+	rates        map[common.Hash]hashrate
+	currentBlock *types.Block
+	currentWork  [4]string
+	notifyCtx    context.Context
+	cancelNotify context.CancelFunc // cancels all notification requests
+	reqWG        sync.WaitGroup     // tracks notification request goroutines
+
+	ethash       *Ethash
+	noverify     bool
+	notifyURLs   []string
+	results      chan<- *types.Block
+	workCh       chan *sealTask   // Notification channel to push new work and relative result channel to remote sealer
+	fetchWorkCh  chan *sealWork   // Channel used for remote sealer to fetch mining work
+	submitWorkCh chan *mineResult // Channel used for remote sealer to submit their mining result
+	fetchRateCh  chan chan uint64 // Channel used to gather submitted hash rate for local or remote sealer.
+	submitRateCh chan *hashrate   // Channel used for remote sealer to submit their mining hashrate
+	requestExit  chan struct{}
+	exitCh       chan struct{}
+}
+
+// sealTask wraps a seal block with relative result channel for remote sealer thread.
+type sealTask struct {
+	block   *types.Block
+	results chan<- *types.Block
+}
+
+// mineResult wraps the pow solution parameters for the specified block.
+type mineResult struct {
+	nonce     types.BlockNonce
+	mixDigest common.Hash
+	hash      common.Hash
+
+	errc chan error
+}
+
+// hashrate wraps the hash rate submitted by the remote sealer.
+type hashrate struct {
+	id   common.Hash
+	ping time.Time
+	rate uint64
+
+	done chan struct{}
+}
+
+// sealWork wraps a seal work package for remote sealer.
+type sealWork struct {
+	errc chan error
+	res  chan [4]string
+}
+
+func startRemoteSealer(ethash *Ethash, urls []string, noverify bool) *remoteSealer {
+	ctx, cancel := context.WithCancel(context.Background())
+	s := &remoteSealer{
+		ethash:       ethash,
+		noverify:     noverify,
+		notifyURLs:   urls,
+		notifyCtx:    ctx,
+		cancelNotify: cancel,
+		works:        make(map[common.Hash]*types.Block),
+		rates:        make(map[common.Hash]hashrate),
+		workCh:       make(chan *sealTask),
+		fetchWorkCh:  make(chan *sealWork),
+		submitWorkCh: make(chan *mineResult),
+		fetchRateCh:  make(chan chan uint64),
+		submitRateCh: make(chan *hashrate),
+		requestExit:  make(chan struct{}),
+		exitCh:       make(chan struct{}),
+	}
+	go s.loop()
+	return s
+}
+
+func (s *remoteSealer) loop() {
+	defer func() {
+		s.ethash.config.Log.Trace("Ethash remote sealer is exiting")
+		s.cancelNotify()
+		s.reqWG.Wait()
+		close(s.exitCh)
+	}()
+
+	ticker := time.NewTicker(5 * time.Second)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case work := <-s.workCh:
+			// Update current work with new received block.
+			// Note same work can be past twice, happens when changing CPU threads.
+			s.results = work.results
+			s.makeWork(work.block)
+			s.notifyWork()
+
+		case work := <-s.fetchWorkCh:
+			// Return current mining work to remote miner.
+			if s.currentBlock == nil {
+				work.errc <- errNoMiningWork
+			} else {
+				work.res <- s.currentWork
+			}
+
+		case result := <-s.submitWorkCh:
+			// Verify submitted PoW solution based on maintained mining blocks.
+			if s.submitWork(result.nonce, result.mixDigest, result.hash) {
+				result.errc <- nil
+			} else {
+				result.errc <- errInvalidSealResult
+			}
+
+		case result := <-s.submitRateCh:
+			// Trace remote sealer's hash rate by submitted value.
+			s.rates[result.id] = hashrate{rate: result.rate, ping: time.Now()}
+			close(result.done)
+
+		case req := <-s.fetchRateCh:
+			// Gather all hash rate submitted by remote sealer.
+			var total uint64
+			for _, rate := range s.rates {
+				// this could overflow
+				total += rate.rate
+			}
+			req <- total
+
+		case <-ticker.C:
+			// Clear stale submitted hash rate.
+			for id, rate := range s.rates {
+				if time.Since(rate.ping) > 10*time.Second {
+					delete(s.rates, id)
+				}
+			}
+			// Clear stale pending blocks
+			if s.currentBlock != nil {
+				for hash, block := range s.works {
+					if block.NumberU64()+staleThreshold <= s.currentBlock.NumberU64() {
+						delete(s.works, hash)
+					}
+				}
+			}
+
+		case <-s.requestExit:
+			return
+		}
+	}
+}
+
+// makeWork creates a work package for external miner.
+//
+// The work package consists of 3 strings:
+//
+//	result[0], 32 bytes hex encoded current block header pow-hash
+//	result[1], 32 bytes hex encoded seed hash used for DAG
+//	result[2], 32 bytes hex encoded boundary condition ("target"), 2^256/difficulty
+//	result[3], hex encoded block number
+func (s *remoteSealer) makeWork(block *types.Block) {
+	hash := s.ethash.SealHash(block.Header())
+	s.currentWork[0] = hash.Hex()
+	s.currentWork[1] = common.BytesToHash(SeedHash(block.NumberU64())).Hex()
+	s.currentWork[2] = common.BytesToHash(new(big.Int).Div(two256, block.Difficulty()).Bytes()).Hex()
+	s.currentWork[3] = hexutil.EncodeBig(block.Number())
+
+	// Trace the seal work fetched by remote sealer.
+	s.currentBlock = block
+	s.works[hash] = block
+}
+
+// notifyWork notifies all the specified mining endpoints of the availability of
+// new work to be processed.
+func (s *remoteSealer) notifyWork() {
+	work := s.currentWork
+
+	// Encode the JSON payload of the notification. When NotifyFull is set,
+	// this is the complete block header, otherwise it is a JSON array.
+	var blob []byte
+	if s.ethash.config.NotifyFull {
+		blob, _ = json.Marshal(s.currentBlock.Header())
+	} else {
+		blob, _ = json.Marshal(work)
+	}
+
+	s.reqWG.Add(len(s.notifyURLs))
+	for _, url := range s.notifyURLs {
+		go s.sendNotification(s.notifyCtx, url, blob, work)
+	}
+}
+
+func (s *remoteSealer) sendNotification(ctx context.Context, url string, json []byte, work [4]string) {
+	defer s.reqWG.Done()
+
+	req, err := http.NewRequest("POST", url, bytes.NewReader(json))
+	if err != nil {
+		s.ethash.config.Log.Warn("Can't create remote miner notification", "err", err)
+		return
+	}
+	ctx, cancel := context.WithTimeout(ctx, remoteSealerTimeout)
+	defer cancel()
+	req = req.WithContext(ctx)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		s.ethash.config.Log.Warn("Failed to notify remote miner", "err", err)
+	} else {
+		s.ethash.config.Log.Trace("Notified remote miner", "miner", url, "hash", work[0], "target", work[2])
+		resp.Body.Close()
+	}
+}
+
+// submitWork verifies the submitted pow solution, returning
+// whether the solution was accepted or not (not can be both a bad pow as well as
+// any other error, like no pending work or stale mining result).
+func (s *remoteSealer) submitWork(nonce types.BlockNonce, mixDigest common.Hash, sealhash common.Hash) bool {
+	if s.currentBlock == nil {
+		s.ethash.config.Log.Error("Pending work without block", "sealhash", sealhash)
+		return false
+	}
+	// Make sure the work submitted is present
+	block := s.works[sealhash]
+	if block == nil {
+		s.ethash.config.Log.Warn("Work submitted but none pending", "sealhash", sealhash, "curnumber", s.currentBlock.NumberU64())
+		return false
+	}
+	// Verify the correctness of submitted result.
+	header := block.Header()
+	header.Nonce = nonce
+	header.MixDigest = mixDigest
+
+	start := time.Now()
+	if !s.noverify {
+		if err := s.ethash.verifySeal(nil, header, true); err != nil {
+			s.ethash.config.Log.Warn("Invalid proof-of-work submitted", "sealhash", sealhash, "elapsed", common.PrettyDuration(time.Since(start)), "err", err)
+			return false
+		}
+	}
+	// Make sure the result channel is assigned.
+	if s.results == nil {
+		s.ethash.config.Log.Warn("Ethash result channel is empty, submitted mining result is rejected")
+		return false
+	}
+	s.ethash.config.Log.Trace("Verified correct proof-of-work", "sealhash", sealhash, "elapsed", common.PrettyDuration(time.Since(start)))
+
+	// Solutions seems to be valid, return to the miner and notify acceptance.
+	solution := block.WithSeal(header)
+
+	// The submitted solution is within the scope of acceptance.
+	if solution.NumberU64()+staleThreshold > s.currentBlock.NumberU64() {
+		select {
+		case s.results <- solution:
+			s.ethash.config.Log.Debug("Work submitted is acceptable", "number", solution.NumberU64(), "sealhash", sealhash, "hash", solution.Hash())
+			return true
+		default:
+			s.ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "remote", "sealhash", sealhash)
+			return false
+		}
+	}
+	// The submitted block is too old to accept, drop it.
+	s.ethash.config.Log.Warn("Work submitted is too old", "number", solution.NumberU64(), "sealhash", sealhash, "hash", solution.Hash())
+	return false
+}

vendor/github.com/ethereum/go-ethereum/consensus/merger.go

@@ -0,0 +1,110 @@
+// Copyright 2021 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 consensus
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/ethereum/go-ethereum/core/rawdb"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/rlp"
+)
+
+// transitionStatus describes the status of eth1/2 transition. This switch
+// between modes is a one-way action which is triggered by corresponding
+// consensus-layer message.
+type transitionStatus struct {
+	LeftPoW    bool // The flag is set when the first NewHead message received
+	EnteredPoS bool // The flag is set when the first FinalisedBlock message received
+}
+
+// Merger is an internal help structure used to track the eth1/2 transition status.
+// It's a common structure can be used in both full node and light client.
+type Merger struct {
+	db     ethdb.KeyValueStore
+	status transitionStatus
+	mu     sync.RWMutex
+}
+
+// NewMerger creates a new Merger which stores its transition status in the provided db.
+func NewMerger(db ethdb.KeyValueStore) *Merger {
+	var status transitionStatus
+	blob := rawdb.ReadTransitionStatus(db)
+	if len(blob) != 0 {
+		if err := rlp.DecodeBytes(blob, &status); err != nil {
+			log.Crit("Failed to decode the transition status", "err", err)
+		}
+	}
+	return &Merger{
+		db:     db,
+		status: status,
+	}
+}
+
+// ReachTTD is called whenever the first NewHead message received
+// from the consensus-layer.
+func (m *Merger) ReachTTD() {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if m.status.LeftPoW {
+		return
+	}
+	m.status = transitionStatus{LeftPoW: true}
+	blob, err := rlp.EncodeToBytes(m.status)
+	if err != nil {
+		panic(fmt.Sprintf("Failed to encode the transition status: %v", err))
+	}
+	rawdb.WriteTransitionStatus(m.db, blob)
+	log.Info("Left PoW stage")
+}
+
+// FinalizePoS is called whenever the first FinalisedBlock message received
+// from the consensus-layer.
+func (m *Merger) FinalizePoS() {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if m.status.EnteredPoS {
+		return
+	}
+	m.status = transitionStatus{LeftPoW: true, EnteredPoS: true}
+	blob, err := rlp.EncodeToBytes(m.status)
+	if err != nil {
+		panic(fmt.Sprintf("Failed to encode the transition status: %v", err))
+	}
+	rawdb.WriteTransitionStatus(m.db, blob)
+	log.Info("Entered PoS stage")
+}
+
+// TDDReached reports whether the chain has left the PoW stage.
+func (m *Merger) TDDReached() bool {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	return m.status.LeftPoW
+}
+
+// PoSFinalized reports whether the chain has entered the PoS stage.
+func (m *Merger) PoSFinalized() bool {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	return m.status.EnteredPoS
+}

vendor/github.com/ethereum/go-ethereum/consensus/misc/dao.go

@@ -0,0 +1,86 @@
+// Copyright 2016 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 misc
+
+import (
+	"bytes"
+	"errors"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+var (
+	// ErrBadProDAOExtra is returned if a header doesn't support the DAO fork on a
+	// pro-fork client.
+	ErrBadProDAOExtra = errors.New("bad DAO pro-fork extra-data")
+
+	// ErrBadNoDAOExtra is returned if a header does support the DAO fork on a no-
+	// fork client.
+	ErrBadNoDAOExtra = errors.New("bad DAO no-fork extra-data")
+)
+
+// VerifyDAOHeaderExtraData validates the extra-data field of a block header to
+// ensure it conforms to DAO hard-fork rules.
+//
+// DAO hard-fork extension to the header validity:
+//
+//   - if the node is no-fork, do not accept blocks in the [fork, fork+10) range
+//     with the fork specific extra-data set.
+//   - if the node is pro-fork, require blocks in the specific range to have the
+//     unique extra-data set.
+func VerifyDAOHeaderExtraData(config *params.ChainConfig, header *types.Header) error {
+	// Short circuit validation if the node doesn't care about the DAO fork
+	if config.DAOForkBlock == nil {
+		return nil
+	}
+	// Make sure the block is within the fork's modified extra-data range
+	limit := new(big.Int).Add(config.DAOForkBlock, params.DAOForkExtraRange)
+	if header.Number.Cmp(config.DAOForkBlock) < 0 || header.Number.Cmp(limit) >= 0 {
+		return nil
+	}
+	// Depending on whether we support or oppose the fork, validate the extra-data contents
+	if config.DAOForkSupport {
+		if !bytes.Equal(header.Extra, params.DAOForkBlockExtra) {
+			return ErrBadProDAOExtra
+		}
+	} else {
+		if bytes.Equal(header.Extra, params.DAOForkBlockExtra) {
+			return ErrBadNoDAOExtra
+		}
+	}
+	// All ok, header has the same extra-data we expect
+	return nil
+}
+
+// ApplyDAOHardFork modifies the state database according to the DAO hard-fork
+// rules, transferring all balances of a set of DAO accounts to a single refund
+// contract.
+func ApplyDAOHardFork(statedb *state.StateDB) {
+	// Retrieve the contract to refund balances into
+	if !statedb.Exist(params.DAORefundContract) {
+		statedb.CreateAccount(params.DAORefundContract)
+	}
+
+	// Move every DAO account and extra-balance account funds into the refund contract
+	for _, addr := range params.DAODrainList() {
+		statedb.AddBalance(params.DAORefundContract, statedb.GetBalance(addr))
+		statedb.SetBalance(addr, new(big.Int))
+	}
+}

vendor/github.com/ethereum/go-ethereum/consensus/misc/eip1559.go

@@ -0,0 +1,93 @@
+// Copyright 2021 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 misc
+
+import (
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/math"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+// 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 {
+	// Verify that the gas limit remains within allowed bounds
+	parentGasLimit := parent.GasLimit
+	if !config.IsLondon(parent.Number) {
+		parentGasLimit = parent.GasLimit * params.ElasticityMultiplier
+	}
+	if err := VerifyGaslimit(parentGasLimit, header.GasLimit); err != nil {
+		return err
+	}
+	// Verify the header is not malformed
+	if header.BaseFee == nil {
+		return fmt.Errorf("header is missing baseFee")
+	}
+	// Verify the baseFee is correct based on the parent header.
+	expectedBaseFee := CalcBaseFee(config, parent)
+	if header.BaseFee.Cmp(expectedBaseFee) != 0 {
+		return fmt.Errorf("invalid baseFee: have %s, want %s, parentBaseFee %s, parentGasUsed %d",
+			header.BaseFee, expectedBaseFee, parent.BaseFee, parent.GasUsed)
+	}
+	return nil
+}
+
+// CalcBaseFee calculates the basefee of the header.
+func CalcBaseFee(config *params.ChainConfig, parent *types.Header) *big.Int {
+	// If the current block is the first EIP-1559 block, return the InitialBaseFee.
+	if !config.IsLondon(parent.Number) {
+		return new(big.Int).SetUint64(params.InitialBaseFee)
+	}
+
+	parentGasTarget := parent.GasLimit / params.ElasticityMultiplier
+	// If the parent gasUsed is the same as the target, the baseFee remains unchanged.
+	if parent.GasUsed == parentGasTarget {
+		return new(big.Int).Set(parent.BaseFee)
+	}
+
+	var (
+		num   = new(big.Int)
+		denom = new(big.Int)
+	)
+
+	if parent.GasUsed > parentGasTarget {
+		// If the parent block used more gas than its target, the baseFee should increase.
+		// max(1, parentBaseFee * gasUsedDelta / parentGasTarget / baseFeeChangeDenominator)
+		num.SetUint64(parent.GasUsed - parentGasTarget)
+		num.Mul(num, parent.BaseFee)
+		num.Div(num, denom.SetUint64(parentGasTarget))
+		num.Div(num, denom.SetUint64(params.BaseFeeChangeDenominator))
+		baseFeeDelta := math.BigMax(num, common.Big1)
+
+		return num.Add(parent.BaseFee, baseFeeDelta)
+	} else {
+		// Otherwise if the parent block used less gas than its target, the baseFee should decrease.
+		// max(0, parentBaseFee * gasUsedDelta / parentGasTarget / baseFeeChangeDenominator)
+		num.SetUint64(parentGasTarget - parent.GasUsed)
+		num.Mul(num, parent.BaseFee)
+		num.Div(num, denom.SetUint64(parentGasTarget))
+		num.Div(num, denom.SetUint64(params.BaseFeeChangeDenominator))
+		baseFee := num.Sub(parent.BaseFee, num)
+
+		return math.BigMax(baseFee, common.Big0)
+	}
+}

vendor/github.com/ethereum/go-ethereum/consensus/misc/forks.go

@@ -0,0 +1,43 @@
+// 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 misc
+
+import (
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+// VerifyForkHashes verifies that blocks conforming to network hard-forks do have
+// the correct hashes, to avoid clients going off on different chains. This is an
+// optional feature.
+func VerifyForkHashes(config *params.ChainConfig, header *types.Header, uncle bool) error {
+	// We don't care about uncles
+	if uncle {
+		return nil
+	}
+	// If the homestead reprice hash is set, validate it
+	if config.EIP150Block != nil && config.EIP150Block.Cmp(header.Number) == 0 {
+		if config.EIP150Hash != (common.Hash{}) && config.EIP150Hash != header.Hash() {
+			return fmt.Errorf("homestead gas reprice fork: have %#x, want %#x", header.Hash(), config.EIP150Hash)
+		}
+	}
+	// All ok, return
+	return nil
+}

vendor/github.com/ethereum/go-ethereum/consensus/misc/gaslimit.go

@@ -0,0 +1,42 @@
+// Copyright 2021 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 misc
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/params"
+)
+
+// VerifyGaslimit verifies the header gas limit according increase/decrease
+// in relation to the parent gas limit.
+func VerifyGaslimit(parentGasLimit, headerGasLimit uint64) error {
+	// Verify that the gas limit remains within allowed bounds
+	diff := int64(parentGasLimit) - int64(headerGasLimit)
+	if diff < 0 {
+		diff *= -1
+	}
+	limit := parentGasLimit / params.GasLimitBoundDivisor
+	if uint64(diff) >= limit {
+		return fmt.Errorf("invalid gas limit: have %d, want %d +-= %d", headerGasLimit, parentGasLimit, limit-1)
+	}
+	if headerGasLimit < params.MinGasLimit {
+		return errors.New("invalid gas limit below 5000")
+	}
+	return nil
+}