github.com/bigzoro/my_simplechain@v0.0.0-20240315012955-8ad0a2a29bb9/consensus/scrypt/consensus.go

// Copyright (c) 2019 Simplechain
//
// This program 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.
//
// This program 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 this program. If not, see <http://www.gnu.org/licenses/>.

package scrypt

import (
	"bytes"
	"errors"
	"fmt"
	"math/big"
	"runtime"
	"time"

	"github.com/bigzoro/my_simplechain/common"
	"github.com/bigzoro/my_simplechain/consensus"
	"github.com/bigzoro/my_simplechain/core/state"
	"github.com/bigzoro/my_simplechain/core/types"
	"github.com/bigzoro/my_simplechain/params"
	"github.com/bigzoro/my_simplechain/rlp"

	mapset "github.com/deckarep/golang-set"
	"golang.org/x/crypto/sha3"
)

// Scrypt proof-of-work protocol constants.
var (
	maxUncles                       = 2                // Maximum number of uncles allowed in a single block
	allowedFutureBlockTime          = 15 * time.Second // Max time from current time allowed for blocks, before they're considered future blocks
	BlockReward            *big.Int = new(big.Int).Mul(big.NewInt(1e+18), big.NewInt(20))
	BlockAttenuation       *big.Int = big.NewInt(2500000)
	big5                   *big.Int = big.NewInt(5)
	big100                 *big.Int = big.NewInt(100)
)

// 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 (
	errZeroBlockTime     = errors.New("timestamp equals parent's")
	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 (powScrypt *PowScrypt) Author(header *types.Header) (common.Address, error) {
	return header.Coinbase, nil
}

// VerifyHeader checks whether a header conforms to the consensus rules of the
// stock Simplechain scrypt engine.
func (powScrypt *PowScrypt) VerifyHeader(chain consensus.ChainReader, header *types.Header, seal bool) error {
	// If we're running a full engine faking, accept any input as valid
	if powScrypt.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 powScrypt.verifyHeader(chain, header, parent, false, seal)
}

// VerifyHeaders is similar to VerifyHeader, but verifies a batch of headers
// concurrently. The method returns a quit channel to abort the operations and
// a results channel to retrieve the async verifications.
func (powScrypt *PowScrypt) VerifyHeaders(chain consensus.ChainReader, headers []*types.Header, seals []bool) (chan<- struct{}, <-chan error) {
	// If we're running a full engine faking, accept any input as valid
	if powScrypt.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{})
	)
	for i := 0; i < workers; i++ {
		go func() {
			for index := range inputs {
				errors[index] = powScrypt.verifyHeaderWorker(chain, headers, seals, index)
				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 (powScrypt *PowScrypt) verifyHeaderWorker(chain consensus.ChainReader, headers []*types.Header, seals []bool, index int) 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
	}
	if chain.GetHeader(headers[index].Hash(), headers[index].Number.Uint64()) != nil {
		return nil // known block
	}
	return powScrypt.verifyHeader(chain, headers[index], parent, false, seals[index])
}

// VerifyUncles verifies that the given block's uncles conform to the consensus
// rules of the stock SimpleChain scrypt engine.
func (powScrypt *PowScrypt) VerifyUncles(chain consensus.ChainReader, block *types.Block) error {
	// If we're running a full engine faking, accept any input as valid
	if powScrypt.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++ {
		ancestor := chain.GetBlock(parent, number)
		if ancestor == nil {
			break
		}
		ancestors[ancestor.Hash()] = ancestor.Header()
		for _, uncle := range ancestor.Uncles() {
			uncles.Add(uncle.Hash())
		}
		parent, number = ancestor.ParentHash(), number-1
	}
	ancestors[block.Hash()] = block.Header()
	uncles.Add(block.Hash())

	// Verify each of the uncles that it's recent, but not an ancestor
	for _, uncle := range block.Uncles() {
		// Make sure every uncle is rewarded only once
		hash := uncle.Hash()
		if uncles.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 := powScrypt.verifyHeader(chain, uncle, ancestors[uncle.ParentHash], true, true); err != nil {
			return err
		}
	}
	return nil
}

// verifyHeader checks whether a header conforms to the consensus rules of the
// stock Simplechain scrypt engine.
// See YP section 4.3.4. "Block Header Validity"
func (powScrypt *PowScrypt) verifyHeader(chain consensus.ChainReader, header, parent *types.Header, uncle bool, seal bool) error {
	// Ensure that the header's extra-data section is of a reasonable size
	if uint64(len(header.Extra)) > params.MaximumExtraDataSize {
		return fmt.Errorf("extra-data too long: %d > %d", len(header.Extra), params.MaximumExtraDataSize)
	}
	// Verify the header's timestamp
	if !uncle {
		if header.Time > uint64(time.Now().Add(allowedFutureBlockTime).Unix()) {
			return consensus.ErrFutureBlock
		}
	}
	if header.Time <= parent.Time {
		return errZeroBlockTime
	}
	// Verify the block's difficulty based in its timestamp and parent's difficulty
	expected := powScrypt.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
	cap := uint64(0x7fffffffffffffff)
	if header.GasLimit > cap {
		return fmt.Errorf("invalid gasLimit: have %v, max %v", header.GasLimit, cap)
	}
	// 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 that the gas limit remains within allowed bounds
	diff := int64(parent.GasLimit) - int64(header.GasLimit)
	if diff < 0 {
		diff *= -1
	}
	limit := parent.GasLimit / params.GasLimitBoundDivisor

	if uint64(diff) >= limit || header.GasLimit < params.MinGasLimit {
		return fmt.Errorf("invalid gas limit: have %d, want %d += %d", header.GasLimit, parent.GasLimit, limit)
	}
	// Verify that the block number is parent's +1
	if diff := new(big.Int).Sub(header.Number, parent.Number); diff.Cmp(big.NewInt(1)) != 0 {
		return consensus.ErrInvalidNumber
	}
	// Verify the engine specific seal securing the block
	if seal {
		if err := powScrypt.VerifySeal(chain, header); err != nil {
			return err
		}
	}
	return nil
}

// CalcDifficulty is the difficulty adjustment algorithm. It returns
// the difficulty that a new block should have when created at time
// given the parent block's time and difficulty.
func (powScrypt *PowScrypt) CalcDifficulty(chain consensus.ChainReader, 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 {
	//TODO: handle forks
	return calcDifficultySimpleChain(time, parent)
}

// Some weird constants to avoid constant memory allocs for them.
var (
	big1         = big.NewInt(1)
	big2         = big.NewInt(2)
	big3         = big.NewInt(3)
	big5000      = big.NewInt(5000)
	big900       = big.NewInt(900)
	big1000      = big.NewInt(1000)
	big100000    = big.NewInt(100000)
	big100000000 = big.NewInt(100000000)
)

func calcDifficultySimpleChain(time uint64, parent *types.Header) *big.Int {
	// diff = 200000
	// parent.UncleHash = 2 if len(parent.uncles) else 1
	// diff =  parent_diff
	//          + parent_diff * ( MIN ( timestamp - parent.timestamp , 900 ) ) ^ 2 * 3 / 100000000
	//          - parent_diff * ( MIN ( timestamp - parent.timestamp , 900 ) ) * 8 / 100000
	//          + parent_diff * parent.UncleHash / 1000
	// diff = max ( diff , 5000 )

	x := big.NewInt(0)
	yn := big.NewInt(0)
	y1 := big.NewInt(0)
	y2 := big.NewInt(0)
	y3 := big.NewInt(0)
	y_uncle := big.NewInt(0)

	bigTime := new(big.Int).SetUint64(time)

	if parent.UncleHash == types.EmptyUncleHash {
		y_uncle.Set(big1)
	} else {
		y_uncle.Set(big2)
	}

	x.Sub(bigTime, new(big.Int).SetUint64(parent.Time))
	timeDiff := x
	if timeDiff.Cmp(big900) > 0 {
		timeDiff.Set(big900)
	}

	y1.Mul(timeDiff, timeDiff)
	y1.Mul(y1, parent.Difficulty)
	y1.Mul(y1, big3)
	y1.Div(y1, big100000000)

	y2.Mul(parent.Difficulty, timeDiff)
	y2.Mul(y2, big8)
	y2.Div(y2, big100000)

	y3.Mul(parent.Difficulty, y_uncle)
	y3.Div(y3, big1000)

	yn.Add(yn, parent.Difficulty)
	yn.Add(yn, y1)
	yn.Sub(yn, y2)
	yn.Add(yn, y3)
	if yn.Cmp(big5000) < 0 {
		yn.Set(big5000)
	}

	return yn
}

// VerifySeal implements consensus.Engine, checking whether the given block satisfies
// the PoW difficulty requirements.
func (powScrypt *PowScrypt) VerifySeal(chain consensus.ChainReader, header *types.Header) error {
	return powScrypt.verifySeal(chain, header)
}

// verifySeal checks whether a block satisfies the PoW difficulty requirements,
func (powScrypt *PowScrypt) verifySeal(chain consensus.ChainReader, header *types.Header) error {
	// If we're running a fake PoW, accept any seal as valid
	if powScrypt.config.PowMode == ModeFake || powScrypt.config.PowMode == ModeFullFake {
		time.Sleep(powScrypt.fakeDelay)
		if powScrypt.fakeFail == header.Number.Uint64() {
			return errInvalidPoW
		}
		return nil
	}
	// Ensure that we have a valid difficulty for the block
	if header.Difficulty.Sign() <= 0 {
		return errInvalidDifficulty
	}

	digest, result := ScryptHash(powScrypt.SealHash(header).Bytes(), header.Nonce.Uint64())

	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 (powScrypt *PowScrypt) Prepare(chain consensus.ChainReader, header *types.Header) error {
	parent := chain.GetHeader(header.ParentHash, header.Number.Uint64()-1)
	if parent == nil {
		return consensus.ErrUnknownAncestor
	}
	header.Difficulty = powScrypt.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 (powScrypt *PowScrypt) Finalize(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, _ []*types.Receipt) error {
	// Accumulate any block and uncle rewards and commit the final state root
	accumulateRewards(chain.Config(), state, header, uncles)
	header.Root = state.IntermediateRoot(true)
	return nil
}

// FinalizeAndAssemble implements consensus.Engine, accumulating the block and
// uncle rewards, setting the final state and assembling the block.
func (powScrypt *PowScrypt) FinalizeAndAssemble(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
	// Accumulate any block and uncle rewards and commit the final state root
	accumulateRewards(chain.Config(), state, header, uncles)
	header.Root = state.IntermediateRoot(true)

	// Header seems complete, assemble into a block and return
	return types.NewBlock(header, txs, uncles, receipts), nil
}

// SealHash returns the hash of a block prior to it being sealed.
func (powScrypt *PowScrypt) SealHash(header *types.Header) (hash common.Hash) {
	hasher := sha3.NewLegacyKeccak256()

	_ = rlp.Encode(hasher, []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,
	})
	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) {
	blockReward := CalculateFixedRewards(header.Number)
	uncleReward := big.NewInt(0)
	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)
		uncleReward.Add(uncleReward, r)
	}

	foundation := CalculateFoundationRewards(header.Number, blockReward)
	blockReward.Sub(blockReward, foundation)
	blockReward.Add(blockReward, uncleReward)
	state.AddBalance(header.Coinbase, blockReward)
	state.AddBalance(params.FoundationAddress, foundation)

}

func CalculateFixedRewards(blockNumber *big.Int) *big.Int {
	reward := new(big.Int).Set(BlockReward)
	number := new(big.Int).Set(blockNumber)
	if number.Sign() == 1 {
		number.Div(number, BlockAttenuation)
		base := big.NewInt(0)
		base.Exp(big.NewInt(2), number, big.NewInt(0))
		reward.Div(reward, base)
	}
	return reward
}

func CalculateFoundationRewards(blockNumber *big.Int, blockReward *big.Int) *big.Int {
	foundation := new(big.Int).Set(blockReward)
	foundation.Mul(foundation, big5)
	number := new(big.Int).Set(blockNumber)
	if number.Sign() == 1 {
		number.Div(number, BlockAttenuation)
		base := big.NewInt(0)
		base.Exp(big.NewInt(2), number, big.NewInt(0))
		foundation.Div(foundation, base)
	}
	foundation.Div(foundation, big100)
	return foundation
}