/
congress.go
1017 lines (878 loc) · 35.6 KB
/
congress.go
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// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// Package congress implements the proof-of-stake-authority consensus engine.
package congress
import (
"bytes"
"errors"
"io"
"math"
"math/big"
"math/rand"
"sort"
"sync"
"time"
"github.com/ethereum/go-ethereum/accounts"
"github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/common"
"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/crypto"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/params"
"github.com/ethereum/go-ethereum/rlp"
"github.com/ethereum/go-ethereum/rpc"
"github.com/ethereum/go-ethereum/trie"
lru "github.com/hashicorp/golang-lru"
"golang.org/x/crypto/sha3"
)
const (
checkpointInterval = 1024 // Number of blocks after which to save the vote snapshot to the database
inmemorySnapshots = 128 // Number of recent vote snapshots to keep in memory
inmemorySignatures = 4096 // Number of recent block signatures to keep in memory
wiggleTime = 500 * time.Millisecond // Random delay (per validator) to allow concurrent validators
maxValidators = 21 // Max validators allowed to seal.
)
// Congress proof-of-stake-authority protocol constants.
var (
epochLength = uint64(30000) // Default number of blocks after which to checkpoint and reset the pending votes
extraVanity = 32 // Fixed number of extra-data prefix bytes reserved for validator vanity
extraSeal = crypto.SignatureLength // Fixed number of extra-data suffix bytes reserved for validator seal
uncleHash = types.CalcUncleHash(nil) // Always Keccak256(RLP([])) as uncles are meaningless outside of PoW.
diffInTurn = big.NewInt(2) // Block difficulty for in-turn signatures
diffNoTurn = big.NewInt(1) // Block difficulty for out-of-turn signatures
)
// System contract address.
var (
validatorsContractName = "validators"
punishContractName = "punish"
proposalContractName = "proposal"
validatorsContractAddr = common.HexToAddress("0x000000000000000000000000000000000000f000")
punishContractAddr = common.HexToAddress("0x000000000000000000000000000000000000f001")
proposalAddr = common.HexToAddress("0x000000000000000000000000000000000000f002")
)
// 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 (
// errUnknownBlock is returned when the list of validators is requested for a block
// that is not part of the local blockchain.
errUnknownBlock = errors.New("unknown block")
// errMissingVanity is returned if a block's extra-data section is shorter than
// 32 bytes, which is required to store the validator vanity.
errMissingVanity = errors.New("extra-data 32 byte vanity prefix missing")
// errMissingSignature is returned if a block's extra-data section doesn't seem
// to contain a 65 byte secp256k1 signature.
errMissingSignature = errors.New("extra-data 65 byte signature suffix missing")
// errExtraValidators is returned if non-checkpoint block contain validator data in
// their extra-data fields.
errExtraValidators = errors.New("non-checkpoint block contains extra validator list")
// errInvalidExtraValidators is returned if validator data in extra-data field is invalid.
errInvalidExtraValidators = errors.New("Invalid extra validators in extra data field")
// errInvalidCheckpointValidators is returned if a checkpoint block contains an
// invalid list of validators (i.e. non divisible by 20 bytes).
errInvalidCheckpointValidators = errors.New("invalid validator list on checkpoint block")
// errMismatchingCheckpointValidators is returned if a checkpoint block contains a
// list of validators different than the one the local node calculated.
errMismatchingCheckpointValidators = errors.New("mismatching validator list on checkpoint block")
// errInvalidMixDigest is returned if a block's mix digest is non-zero.
errInvalidMixDigest = errors.New("non-zero mix digest")
// errInvalidUncleHash is returned if a block contains an non-empty uncle list.
errInvalidUncleHash = errors.New("non empty uncle hash")
// errInvalidDifficulty is returned if the difficulty of a block neither 1 or 2.
errInvalidDifficulty = errors.New("invalid difficulty")
// errWrongDifficulty is returned if the difficulty of a block doesn't match the
// turn of the validator.
errWrongDifficulty = errors.New("wrong difficulty")
// errInvalidTimestamp is returned if the timestamp of a block is lower than
// the previous block's timestamp + the minimum block period.
errInvalidTimestamp = errors.New("invalid timestamp")
// ErrInvalidTimestamp is returned if the timestamp of a block is lower than
// the previous block's timestamp + the minimum block period.
ErrInvalidTimestamp = errors.New("invalid timestamp")
// errInvalidVotingChain is returned if an authorization list is attempted to
// be modified via out-of-range or non-contiguous headers.
errInvalidVotingChain = errors.New("invalid voting chain")
// errUnauthorizedValidator is returned if a header is signed by a non-authorized entity.
errUnauthorizedValidator = errors.New("unauthorized validator")
// errRecentlySigned is returned if a header is signed by an authorized entity
// that already signed a header recently, thus is temporarily not allowed to.
errRecentlySigned = errors.New("recently signed")
// errInvalidValidatorLen is returned if validators length is zero or bigger than maxValidators.
errInvalidValidatorsLength = errors.New("Invalid validators length")
// errInvalidCoinbase is returned if the coinbase isn't the validator of the block.
errInvalidCoinbase = errors.New("Invalid coin base")
)
// StateFn gets state by the state root hash.
type StateFn func(hash common.Hash) (*state.StateDB, error)
// ValidatorFn hashes and signs the data to be signed by a backing account.
type ValidatorFn func(validator accounts.Account, mimeType string, message []byte) ([]byte, error)
// ecrecover extracts the Ethereum account address from a signed header.
func ecrecover(header *types.Header, sigcache *lru.ARCCache) (common.Address, error) {
// If the signature's already cached, return that
hash := header.Hash()
if address, known := sigcache.Get(hash); known {
return address.(common.Address), nil
}
// Retrieve the signature from the header extra-data
if len(header.Extra) < extraSeal {
return common.Address{}, errMissingSignature
}
signature := header.Extra[len(header.Extra)-extraSeal:]
// Recover the public key and the Ethereum address
pubkey, err := crypto.Ecrecover(SealHash(header).Bytes(), signature)
if err != nil {
return common.Address{}, err
}
var validator common.Address
copy(validator[:], crypto.Keccak256(pubkey[1:])[12:])
sigcache.Add(hash, validator)
return validator, nil
}
// Congress is the proof-of-stake-authority consensus engine proposed to support the
// Ethereum testnet following the Ropsten attacks.
type Congress struct {
chainConfig *params.ChainConfig // ChainConfig to execute evm
config *params.CongressConfig // Consensus engine configuration parameters
db ethdb.Database // Database to store and retrieve snapshot checkpoints
recents *lru.ARCCache // Snapshots for recent block to speed up reorgs
signatures *lru.ARCCache // Signatures of recent blocks to speed up mining
proposals map[common.Address]bool // Current list of proposals we are pushing
validator common.Address // Ethereum address of the signing key
signFn ValidatorFn // Validator function to authorize hashes with
lock sync.RWMutex // Protects the validator fields
stateFn StateFn // Function to get state by state root
abi map[string]abi.ABI // Interactive with system contracts
// The fields below are for testing only
fakeDiff bool // Skip difficulty verifications
}
// New creates a Congress proof-of-stake-authority consensus engine with the initial
// validators set to the ones provided by the user.
func New(chainConfig *params.ChainConfig, db ethdb.Database) *Congress {
// Set any missing consensus parameters to their defaults
conf := *chainConfig.Congress
if conf.Epoch == 0 {
conf.Epoch = epochLength
}
// Allocate the snapshot caches and create the engine
recents, _ := lru.NewARC(inmemorySnapshots)
signatures, _ := lru.NewARC(inmemorySignatures)
abi := getInteractiveABI()
return &Congress{
chainConfig: chainConfig,
config: &conf,
db: db,
recents: recents,
signatures: signatures,
proposals: make(map[common.Address]bool),
abi: abi,
}
}
// SetStateFn sets the function to get state.
func (c *Congress) SetStateFn(fn StateFn) {
c.stateFn = fn
}
// Author implements consensus.Engine, returning the Ethereum address recovered
// from the signature in the header's extra-data section.
func (c *Congress) Author(header *types.Header) (common.Address, error) {
return header.Coinbase, nil
// return ecrecover(header, c.signatures)
}
// VerifyHeader checks whether a header conforms to the consensus rules.
func (c *Congress) VerifyHeader(chain consensus.ChainHeaderReader, header *types.Header, seal bool) error {
return c.verifyHeader(chain, header, nil)
}
// VerifyHeaders is similar to VerifyHeader, but verifies a batch of headers. 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).
func (c *Congress) VerifyHeaders(chain consensus.ChainHeaderReader, headers []*types.Header, seals []bool) (chan<- struct{}, <-chan error) {
abort := make(chan struct{})
results := make(chan error, len(headers))
go func() {
for i, header := range headers {
err := c.verifyHeader(chain, header, headers[:i])
select {
case <-abort:
return
case results <- err:
}
}
}()
return abort, results
}
// verifyHeader checks whether a header conforms to the consensus rules.The
// caller may optionally pass in a batch of parents (ascending order) to avoid
// looking those up from the database. This is useful for concurrently verifying
// a batch of new headers.
func (c *Congress) verifyHeader(chain consensus.ChainHeaderReader, header *types.Header, parents []*types.Header) error {
if header.Number == nil {
return errUnknownBlock
}
number := header.Number.Uint64()
// Don't waste time checking blocks from the future
if header.Time > uint64(time.Now().Unix()) {
return consensus.ErrFutureBlock
}
// Check that the extra-data contains the vanity, validators and signature.
if len(header.Extra) < extraVanity {
return errMissingVanity
}
if len(header.Extra) < extraVanity+extraSeal {
return errMissingSignature
}
// check extra data
isEpoch := number%c.config.Epoch == 0
// Ensure that the extra-data contains a validator list on checkpoint, but none otherwise
validatorsBytes := len(header.Extra) - extraVanity - extraSeal
if !isEpoch && validatorsBytes != 0 {
return errExtraValidators
}
// Ensure that the validator bytes length is valid
if isEpoch && validatorsBytes%common.AddressLength != 0 {
return errExtraValidators
}
// Ensure that the mix digest is zero as we don't have fork protection currently
if header.MixDigest != (common.Hash{}) {
return errInvalidMixDigest
}
// Ensure that the block doesn't contain any uncles which are meaningless in PoA
if header.UncleHash != uncleHash {
return errInvalidUncleHash
}
// Ensure that the block's difficulty is meaningful (may not be correct at this point)
if number > 0 && header.Difficulty == nil {
return errInvalidDifficulty
}
// If all checks passed, validate any special fields for hard forks
if err := misc.VerifyForkHashes(chain.Config(), header, false); err != nil {
return err
}
// All basic checks passed, verify cascading fields
return c.verifyCascadingFields(chain, header, parents)
}
// verifyCascadingFields verifies all the header fields that are not standalone,
// rather depend on a batch of previous headers. The caller may optionally pass
// in a batch of parents (ascending order) to avoid looking those up from the
// database. This is useful for concurrently verifying a batch of new headers.
func (c *Congress) verifyCascadingFields(chain consensus.ChainHeaderReader, header *types.Header, parents []*types.Header) error {
// The genesis block is the always valid dead-end
number := header.Number.Uint64()
if number == 0 {
return nil
}
var parent *types.Header
if len(parents) > 0 {
parent = parents[len(parents)-1]
} else {
parent = chain.GetHeader(header.ParentHash, number-1)
}
if parent == nil || parent.Number.Uint64() != number-1 || parent.Hash() != header.ParentHash {
return consensus.ErrUnknownAncestor
}
if parent.Time+c.config.Period > header.Time {
return ErrInvalidTimestamp
}
// All basic checks passed, verify the seal and return
return c.verifySeal(chain, header, parents)
}
// snapshot retrieves the authorization snapshot at a given point in time.
func (c *Congress) snapshot(chain consensus.ChainHeaderReader, number uint64, hash common.Hash, parents []*types.Header) (*Snapshot, error) {
// Search for a snapshot in memory or on disk for checkpoints
var (
headers []*types.Header
snap *Snapshot
)
for snap == nil {
// If an in-memory snapshot was found, use that
if s, ok := c.recents.Get(hash); ok {
snap = s.(*Snapshot)
break
}
// If an on-disk checkpoint snapshot can be found, use that
if number%checkpointInterval == 0 {
if s, err := loadSnapshot(c.config, c.signatures, c.db, hash); err == nil {
log.Trace("Loaded voting snapshot from disk", "number", number, "hash", hash)
snap = s
break
}
}
// If we're at the genesis, snapshot the initial state. Alternatively if we're
// at a checkpoint block without a parent (light client CHT), or we have piled
// up more headers than allowed to be reorged (chain reinit from a freezer),
// consider the checkpoint trusted and snapshot it.
if number == 0 || (number%c.config.Epoch == 0 && (len(headers) > params.FullImmutabilityThreshold || chain.GetHeaderByNumber(number-1) == nil)) {
checkpoint := chain.GetHeaderByNumber(number)
if checkpoint != nil {
hash := checkpoint.Hash()
validators := make([]common.Address, (len(checkpoint.Extra)-extraVanity-extraSeal)/common.AddressLength)
for i := 0; i < len(validators); i++ {
copy(validators[i][:], checkpoint.Extra[extraVanity+i*common.AddressLength:])
}
snap = newSnapshot(c.config, c.signatures, number, hash, validators)
if err := snap.store(c.db); err != nil {
return nil, err
}
log.Info("Stored checkpoint snapshot to disk", "number", number, "hash", hash)
break
}
}
// No snapshot for this header, gather the header and move backward
var header *types.Header
if len(parents) > 0 {
// If we have explicit parents, pick from there (enforced)
header = parents[len(parents)-1]
if header.Hash() != hash || header.Number.Uint64() != number {
return nil, consensus.ErrUnknownAncestor
}
parents = parents[:len(parents)-1]
} else {
// No explicit parents (or no more left), reach out to the database
header = chain.GetHeader(hash, number)
if header == nil {
return nil, consensus.ErrUnknownAncestor
}
}
headers = append(headers, header)
number, hash = number-1, header.ParentHash
}
// Previous snapshot found, apply any pending headers on top of it
for i := 0; i < len(headers)/2; i++ {
headers[i], headers[len(headers)-1-i] = headers[len(headers)-1-i], headers[i]
}
snap, err := snap.apply(headers, chain, parents)
if err != nil {
return nil, err
}
c.recents.Add(snap.Hash, snap)
// If we've generated a new checkpoint snapshot, save to disk
if snap.Number%checkpointInterval == 0 && len(headers) > 0 {
if err = snap.store(c.db); err != nil {
return nil, err
}
log.Trace("Stored voting snapshot to disk", "number", snap.Number, "hash", snap.Hash)
}
return snap, err
}
// VerifyUncles implements consensus.Engine, always returning an error for any
// uncles as this consensus mechanism doesn't permit uncles.
func (c *Congress) VerifyUncles(chain consensus.ChainReader, block *types.Block) error {
if len(block.Uncles()) > 0 {
return errors.New("uncles not allowed")
}
return nil
}
// VerifySeal implements consensus.Engine, checking whether the signature contained
// in the header satisfies the consensus protocol requirements.
func (c *Congress) VerifySeal(chain consensus.ChainHeaderReader, header *types.Header) error {
return c.verifySeal(chain, header, nil)
}
// verifySeal checks whether the signature contained in the header satisfies the
// consensus protocol requirements. The method accepts an optional list of parent
// headers that aren't yet part of the local blockchain to generate the snapshots
// from.
func (c *Congress) verifySeal(chain consensus.ChainHeaderReader, header *types.Header, parents []*types.Header) error {
// Verifying the genesis block is not supported
number := header.Number.Uint64()
if number == 0 {
return errUnknownBlock
}
// Retrieve the snapshot needed to verify this header and cache it
snap, err := c.snapshot(chain, number-1, header.ParentHash, parents)
if err != nil {
return err
}
// Resolve the authorization key and check against validators
signer, err := ecrecover(header, c.signatures)
if err != nil {
return err
}
if signer != header.Coinbase {
return errInvalidCoinbase
}
if _, ok := snap.Validators[signer]; !ok {
return errUnauthorizedValidator
}
for seen, recent := range snap.Recents {
if recent == signer {
// Validator is among recents, only fail if the current block doesn't shift it out
if limit := uint64(len(snap.Validators)/2 + 1); seen > number-limit {
return errRecentlySigned
}
}
}
// Ensure that the difficulty corresponds to the turn-ness of the signer
if !c.fakeDiff {
inturn := snap.inturn(header.Number.Uint64(), signer)
if inturn && header.Difficulty.Cmp(diffInTurn) != 0 {
return errWrongDifficulty
}
if !inturn && header.Difficulty.Cmp(diffNoTurn) != 0 {
return errWrongDifficulty
}
}
return nil
}
// Prepare implements consensus.Engine, preparing all the consensus fields of the
// header for running the transactions on top.
func (c *Congress) Prepare(chain consensus.ChainHeaderReader, header *types.Header) error {
// If the block isn't a checkpoint, cast a random vote (good enough for now)
header.Coinbase = c.validator
header.Nonce = types.BlockNonce{}
number := header.Number.Uint64()
snap, err := c.snapshot(chain, number-1, header.ParentHash, nil)
if err != nil {
return err
}
// Set the correct difficulty
header.Difficulty = calcDifficulty(snap, c.validator)
// Ensure the extra data has all its components
if len(header.Extra) < extraVanity {
header.Extra = append(header.Extra, bytes.Repeat([]byte{0x00}, extraVanity-len(header.Extra))...)
}
header.Extra = header.Extra[:extraVanity]
if number%c.config.Epoch == 0 {
newSortedValidators, err := c.getTopValidators(chain, header)
if err != nil {
return err
}
for _, validator := range newSortedValidators {
header.Extra = append(header.Extra, validator.Bytes()...)
}
}
header.Extra = append(header.Extra, make([]byte, extraSeal)...)
// Mix digest is reserved for now, set to empty
header.MixDigest = common.Hash{}
// Ensure the timestamp has the correct delay
parent := chain.GetHeader(header.ParentHash, number-1)
if parent == nil {
return consensus.ErrUnknownAncestor
}
header.Time = parent.Time + c.config.Period
if header.Time < uint64(time.Now().Unix()) {
header.Time = uint64(time.Now().Unix())
}
return nil
}
// Finalize implements consensus.Engine, ensuring no uncles are set, nor block
// rewards given.
func (c *Congress) Finalize(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header) error {
// Initialize all system contracts at block 1.
if header.Number.Cmp(common.Big1) == 0 {
if err := c.initializeSystemContracts(chain, header, state); err != nil {
log.Error("Initialize system contracts failed", "err", err)
return err
}
}
if header.Difficulty.Cmp(diffInTurn) != 0 {
if err := c.tryPunishValidator(chain, header, state); err != nil {
return err
}
}
// execute block reward tx.
if len(txs) > 0 {
if err := c.trySendBlockReward(chain, header, state); err != nil {
return err
}
}
// do epoch thing at the end, because it will update active validators
if header.Number.Uint64()%c.config.Epoch == 0 {
newValidators, err := c.doSomethingAtEpoch(chain, header, state)
if err != nil {
return err
}
validatorsBytes := make([]byte, len(newValidators)*common.AddressLength)
for i, validator := range newValidators {
copy(validatorsBytes[i*common.AddressLength:], validator.Bytes())
}
extraSuffix := len(header.Extra) - extraSeal
if !bytes.Equal(header.Extra[extraVanity:extraSuffix], validatorsBytes) {
return errInvalidExtraValidators
}
}
// No block rewards in PoA, so the state remains as is and uncles are dropped
header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
header.UncleHash = types.CalcUncleHash(nil)
return nil
}
// FinalizeAndAssemble implements consensus.Engine, ensuring no uncles are set,
// nor block rewards given, and returns the final block.
func (c *Congress) FinalizeAndAssemble(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
// Initialize all system contracts at block 1.
if header.Number.Cmp(common.Big1) == 0 {
if err := c.initializeSystemContracts(chain, header, state); err != nil {
panic(err)
}
}
// punish validator if necessary
if header.Difficulty.Cmp(diffInTurn) != 0 {
if err := c.tryPunishValidator(chain, header, state); err != nil {
panic(err)
}
}
// deposit block reward if any tx exists.
if len(txs) > 0 {
if err := c.trySendBlockReward(chain, header, state); err != nil {
panic(err)
}
}
// do epoch thing at the end, because it will update active validators
if header.Number.Uint64()%c.config.Epoch == 0 {
if _, err := c.doSomethingAtEpoch(chain, header, state); err != nil {
panic(err)
}
}
// No block rewards in PoA, so the state remains as is and uncles are dropped
header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
header.UncleHash = types.CalcUncleHash(nil)
// Assemble and return the final block for sealing
return types.NewBlock(header, txs, nil, receipts, new(trie.Trie)), nil
}
func (c *Congress) trySendBlockReward(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB) error {
fee := state.GetBalance(consensus.FeeRecoder)
if fee.Cmp(common.Big0) <= 0 {
return nil
}
// Miner will send tx to deposit block fees to contract, add to his balance first.
state.AddBalance(header.Coinbase, fee)
// reset fee
state.SetBalance(consensus.FeeRecoder, common.Big0)
method := "distributeBlockReward"
data, err := c.abi[validatorsContractName].Pack(method)
if err != nil {
log.Error("Can't pack data for distributeBlockReward", "err", err)
return err
}
nonce := state.GetNonce(header.Coinbase)
msg := types.NewMessage(header.Coinbase, &validatorsContractAddr, nonce, fee, math.MaxUint64, new(big.Int), data, true)
if _, err := executeMsg(msg, state, header, newChainContext(chain, c), c.chainConfig); err != nil {
return err
}
return nil
}
func (c *Congress) tryPunishValidator(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB) error {
number := header.Number.Uint64()
snap, err := c.snapshot(chain, number-1, header.ParentHash, nil)
if err != nil {
return err
}
validators := snap.validators()
outTurnValidator := validators[number%uint64(len(validators))]
// check sigend recently or not
signedRecently := false
for _, recent := range snap.Recents {
if recent == outTurnValidator {
signedRecently = true
break
}
}
if !signedRecently {
if err := c.punishValidator(outTurnValidator, chain, header, state); err != nil {
return err
}
}
return nil
}
func (c *Congress) doSomethingAtEpoch(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB) ([]common.Address, error) {
newSortedValidators, err := c.getTopValidators(chain, header)
if err != nil {
return []common.Address{}, err
}
// update contract new validators if new set exists
if err := c.updateValidators(newSortedValidators, chain, header, state); err != nil {
return []common.Address{}, err
}
// decrease validator missed blocks counter at epoch
if err := c.decreaseMissedBlocksCounter(chain, header, state); err != nil {
return []common.Address{}, err
}
return newSortedValidators, nil
}
// initializeSystemContracts initializes all system contracts.
func (c *Congress) initializeSystemContracts(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB) error {
snap, err := c.snapshot(chain, 0, header.ParentHash, nil)
if err != nil {
return err
}
genesisValidators := snap.validators()
if len(genesisValidators) == 0 || len(genesisValidators) > maxValidators {
return errInvalidValidatorsLength
}
method := "initialize"
contracts := []struct {
addr common.Address
packFun func() ([]byte, error)
}{
{validatorsContractAddr, func() ([]byte, error) {
return c.abi[validatorsContractName].Pack(method, genesisValidators)
}},
{punishContractAddr, func() ([]byte, error) { return c.abi[punishContractName].Pack(method) }},
{proposalAddr, func() ([]byte, error) { return c.abi[proposalContractName].Pack(method, genesisValidators) }},
}
for _, contract := range contracts {
data, err := contract.packFun()
if err != nil {
return err
}
nonce := state.GetNonce(header.Coinbase)
msg := types.NewMessage(header.Coinbase, &contract.addr, nonce, new(big.Int), math.MaxUint64, new(big.Int), data, true)
if _, err := executeMsg(msg, state, header, newChainContext(chain, c), c.chainConfig); err != nil {
return err
}
}
return nil
}
// call this at epoch block to get top validators based on the state of epoch block - 1
func (c *Congress) getTopValidators(chain consensus.ChainHeaderReader, header *types.Header) ([]common.Address, error) {
parent := chain.GetHeader(header.ParentHash, header.Number.Uint64()-1)
if parent == nil {
return []common.Address{}, consensus.ErrUnknownAncestor
}
statedb, err := c.stateFn(parent.Root)
if err != nil {
return []common.Address{}, err
}
method := "getTopValidators"
data, err := c.abi[validatorsContractName].Pack(method)
if err != nil {
log.Error("Can't pack data for getTopValidators", "error", err)
return []common.Address{}, err
}
msg := types.NewMessage(header.Coinbase, &validatorsContractAddr, 0, new(big.Int), math.MaxUint64, new(big.Int), data, false)
// use parent
result, err := executeMsg(msg, statedb, parent, newChainContext(chain, c), c.chainConfig)
if err != nil {
return []common.Address{}, err
}
// unpack data
ret, err := c.abi[validatorsContractName].Unpack(method, result)
if err != nil {
return []common.Address{}, err
}
if len(ret) != 1 {
return []common.Address{}, errors.New("Invalid params length")
}
validators, ok := ret[0].([]common.Address)
if !ok {
return []common.Address{}, errors.New("Invalid validators format")
}
sort.Sort(validatorsAscending(validators))
return validators, err
}
func (c *Congress) updateValidators(vals []common.Address, chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB) error {
// method
method := "updateActiveValidatorSet"
data, err := c.abi[validatorsContractName].Pack(method, vals, new(big.Int).SetUint64(c.config.Epoch))
if err != nil {
log.Error("Can't pack data for updateActiveValidatorSet", "error", err)
return err
}
// call contract
nonce := state.GetNonce(header.Coinbase)
msg := types.NewMessage(header.Coinbase, &validatorsContractAddr, nonce, new(big.Int), math.MaxUint64, new(big.Int), data, true)
if _, err := executeMsg(msg, state, header, newChainContext(chain, c), c.chainConfig); err != nil {
log.Error("Can't update validators to contract", "err", err)
return err
}
return nil
}
func (c *Congress) punishValidator(val common.Address, chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB) error {
// method
method := "punish"
data, err := c.abi[punishContractName].Pack(method, val)
if err != nil {
log.Error("Can't pack data for punish", "error", err)
return err
}
// call contract
nonce := state.GetNonce(header.Coinbase)
msg := types.NewMessage(header.Coinbase, &punishContractAddr, nonce, new(big.Int), math.MaxUint64, new(big.Int), data, true)
if _, err := executeMsg(msg, state, header, newChainContext(chain, c), c.chainConfig); err != nil {
log.Error("Can't punish validator", "err", err)
return err
}
return nil
}
func (c *Congress) decreaseMissedBlocksCounter(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB) error {
// method
method := "decreaseMissedBlocksCounter"
data, err := c.abi[punishContractName].Pack(method, new(big.Int).SetUint64(c.config.Epoch))
if err != nil {
log.Error("Can't pack data for decreaseMissedBlocksCounter", "error", err)
return err
}
// call contract
nonce := state.GetNonce(header.Coinbase)
msg := types.NewMessage(header.Coinbase, &punishContractAddr, nonce, new(big.Int), math.MaxUint64, new(big.Int), data, true)
if _, err := executeMsg(msg, state, header, newChainContext(chain, c), c.chainConfig); err != nil {
log.Error("Can't decrease missed blocks counter for validator", "err", err)
return err
}
return nil
}
// Authorize injects a private key into the consensus engine to mint new blocks
// with.
func (c *Congress) Authorize(validator common.Address, signFn ValidatorFn) {
c.lock.Lock()
defer c.lock.Unlock()
c.validator = validator
c.signFn = signFn
}
// Seal implements consensus.Engine, attempting to create a sealed block using
// the local signing credentials.
func (c *Congress) Seal(chain consensus.ChainHeaderReader, block *types.Block, results chan<- *types.Block, stop <-chan struct{}) error {
header := block.Header()
// Sealing the genesis block is not supported
number := header.Number.Uint64()
if number == 0 {
return errUnknownBlock
}
// For 0-period chains, refuse to seal empty blocks (no reward but would spin sealing)
if c.config.Period == 0 && len(block.Transactions()) == 0 {
log.Info("Sealing paused, waiting for transactions")
return nil
}
// Don't hold the val fields for the entire sealing procedure
c.lock.RLock()
val, signFn := c.validator, c.signFn
c.lock.RUnlock()
// Bail out if we're unauthorized to sign a block
snap, err := c.snapshot(chain, number-1, header.ParentHash, nil)
if err != nil {
return err
}
if _, authorized := snap.Validators[val]; !authorized {
return errUnauthorizedValidator
}
// If we're amongst the recent validators, wait for the next block
for seen, recent := range snap.Recents {
if recent == val {
// Validator is among recents, only wait if the current block doesn't shift it out
if limit := uint64(len(snap.Validators)/2 + 1); number < limit || seen > number-limit {
log.Info("Signed recently, must wait for others")
return nil
}
}
}
// Sweet, the protocol permits us to sign the block, wait for our time
delay := time.Unix(int64(header.Time), 0).Sub(time.Now()) // nolint: gosimple
if header.Difficulty.Cmp(diffNoTurn) == 0 {
// It's not our turn explicitly to sign, delay it a bit
wiggle := time.Duration(len(snap.Validators)/2+1) * wiggleTime
delay += time.Duration(rand.Int63n(int64(wiggle)))
log.Trace("Out-of-turn signing requested", "wiggle", common.PrettyDuration(wiggle))
}
// Sign all the things!
sighash, err := signFn(accounts.Account{Address: val}, accounts.MimetypeCongress, CongressRLP(header))
if err != nil {
return err
}
copy(header.Extra[len(header.Extra)-extraSeal:], sighash)
// Wait until sealing is terminated or delay timeout.
log.Trace("Waiting for slot to sign and propagate", "delay", common.PrettyDuration(delay))
go func() {
select {
case <-stop:
return
case <-time.After(delay):
}
select {
case results <- block.WithSeal(header):
default:
log.Warn("Sealing result is not read by miner", "sealhash", SealHash(header))
}
}()
return nil
}
// CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
// that a new block should have:
// * DIFF_NOTURN(2) if BLOCK_NUMBER % validator_COUNT != validator_INDEX
// * DIFF_INTURN(1) if BLOCK_NUMBER % validator_COUNT == validator_INDEX
func (c *Congress) CalcDifficulty(chain consensus.ChainHeaderReader, time uint64, parent *types.Header) *big.Int {
snap, err := c.snapshot(chain, parent.Number.Uint64(), parent.Hash(), nil)
if err != nil {
return nil
}
return calcDifficulty(snap, c.validator)
}
func calcDifficulty(snap *Snapshot, validator common.Address) *big.Int {
if snap.inturn(snap.Number+1, validator) {
return new(big.Int).Set(diffInTurn)
}
return new(big.Int).Set(diffNoTurn)
}
// SealHash returns the hash of a block prior to it being sealed.
func (c *Congress) SealHash(header *types.Header) common.Hash {
return SealHash(header)
}
// Close implements consensus.Engine. It's a noop for congress as there are no background threads.
func (c *Congress) Close() error {
return nil
}
// APIs implements consensus.Engine, returning the user facing RPC API to allow
// controlling the validator voting.
func (c *Congress) APIs(chain consensus.ChainHeaderReader) []rpc.API {
return []rpc.API{{
Namespace: "congress",
Version: "1.0",
Service: &API{chain: chain, congress: c},
Public: false,
}}
}
// SealHash returns the hash of a block prior to it being sealed.
func SealHash(header *types.Header) (hash common.Hash) {
hasher := sha3.NewLegacyKeccak256()
encodeSigHeader(hasher, header)
hasher.Sum(hash[:0])
return hash
}
// CongressRLP returns the rlp bytes which needs to be signed for the proof-of-stake-authority
// sealing. The RLP to sign consists of the entire header apart from the 65 byte signature
// contained at the end of the extra data.
//
// Note, the method requires the extra data to be at least 65 bytes, otherwise it
// panics. This is done to avoid accidentally using both forms (signature present
// or not), which could be abused to produce different hashes for the same header.
func CongressRLP(header *types.Header) []byte {
b := new(bytes.Buffer)
encodeSigHeader(b, header)
return b.Bytes()
}
func encodeSigHeader(w io.Writer, header *types.Header) {
err := rlp.Encode(w, []interface{}{
header.ParentHash,
header.UncleHash,
header.Coinbase,