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-rw-r--r--consensus/clique/api.go119
-rw-r--r--consensus/clique/clique.go742
-rw-r--r--consensus/clique/snapshot.go326
3 files changed, 1187 insertions, 0 deletions
diff --git a/consensus/clique/api.go b/consensus/clique/api.go
new file mode 100644
index 0000000..04e74eb
--- /dev/null
+++ b/consensus/clique/api.go
@@ -0,0 +1,119 @@
+// 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 clique
+
+import (
+ "github.com/ava-labs/coreth/consensus"
+ "github.com/ava-labs/coreth/core/types"
+ "github.com/ava-labs/coreth/rpc"
+ "github.com/ava-labs/go-ethereum/common"
+)
+
+// API is a user facing RPC API to allow controlling the signer and voting
+// mechanisms of the proof-of-authority scheme.
+type API struct {
+ chain consensus.ChainReader
+ clique *Clique
+}
+
+// GetSnapshot retrieves the state snapshot at a given block.
+func (api *API) GetSnapshot(number *rpc.BlockNumber) (*Snapshot, error) {
+ // Retrieve the requested block number (or current if none requested)
+ var header *types.Header
+ if number == nil || *number == rpc.LatestBlockNumber {
+ header = api.chain.CurrentHeader()
+ } else {
+ header = api.chain.GetHeaderByNumber(uint64(number.Int64()))
+ }
+ // Ensure we have an actually valid block and return its snapshot
+ if header == nil {
+ return nil, errUnknownBlock
+ }
+ return api.clique.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
+}
+
+// GetSnapshotAtHash retrieves the state snapshot at a given block.
+func (api *API) GetSnapshotAtHash(hash common.Hash) (*Snapshot, error) {
+ header := api.chain.GetHeaderByHash(hash)
+ if header == nil {
+ return nil, errUnknownBlock
+ }
+ return api.clique.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
+}
+
+// GetSigners retrieves the list of authorized signers at the specified block.
+func (api *API) GetSigners(number *rpc.BlockNumber) ([]common.Address, error) {
+ // Retrieve the requested block number (or current if none requested)
+ var header *types.Header
+ if number == nil || *number == rpc.LatestBlockNumber {
+ header = api.chain.CurrentHeader()
+ } else {
+ header = api.chain.GetHeaderByNumber(uint64(number.Int64()))
+ }
+ // Ensure we have an actually valid block and return the signers from its snapshot
+ if header == nil {
+ return nil, errUnknownBlock
+ }
+ snap, err := api.clique.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
+ if err != nil {
+ return nil, err
+ }
+ return snap.signers(), nil
+}
+
+// GetSignersAtHash retrieves the list of authorized signers at the specified block.
+func (api *API) GetSignersAtHash(hash common.Hash) ([]common.Address, error) {
+ header := api.chain.GetHeaderByHash(hash)
+ if header == nil {
+ return nil, errUnknownBlock
+ }
+ snap, err := api.clique.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
+ if err != nil {
+ return nil, err
+ }
+ return snap.signers(), nil
+}
+
+// Proposals returns the current proposals the node tries to uphold and vote on.
+func (api *API) Proposals() map[common.Address]bool {
+ api.clique.lock.RLock()
+ defer api.clique.lock.RUnlock()
+
+ proposals := make(map[common.Address]bool)
+ for address, auth := range api.clique.proposals {
+ proposals[address] = auth
+ }
+ return proposals
+}
+
+// Propose injects a new authorization proposal that the signer will attempt to
+// push through.
+func (api *API) Propose(address common.Address, auth bool) {
+ api.clique.lock.Lock()
+ defer api.clique.lock.Unlock()
+
+ api.clique.proposals[address] = auth
+}
+
+// Discard drops a currently running proposal, stopping the signer from casting
+// further votes (either for or against).
+func (api *API) Discard(address common.Address) {
+ api.clique.lock.Lock()
+ defer api.clique.lock.Unlock()
+
+ delete(api.clique.proposals, address)
+}
diff --git a/consensus/clique/clique.go b/consensus/clique/clique.go
new file mode 100644
index 0000000..3714733
--- /dev/null
+++ b/consensus/clique/clique.go
@@ -0,0 +1,742 @@
+// 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 clique implements the proof-of-authority consensus engine.
+package clique
+
+import (
+ "bytes"
+ "errors"
+ "io"
+ "math/big"
+ "math/rand"
+ "sync"
+ "time"
+
+ "github.com/ava-labs/coreth/accounts"
+ "github.com/ava-labs/coreth/consensus"
+ "github.com/ava-labs/coreth/consensus/misc"
+ "github.com/ava-labs/coreth/core/state"
+ "github.com/ava-labs/coreth/core/types"
+ "github.com/ava-labs/coreth/params"
+ "github.com/ava-labs/coreth/rpc"
+ "github.com/ava-labs/go-ethereum/common"
+ "github.com/ava-labs/go-ethereum/common/hexutil"
+ "github.com/ava-labs/go-ethereum/crypto"
+ "github.com/ava-labs/go-ethereum/ethdb"
+ "github.com/ava-labs/go-ethereum/log"
+ "github.com/ava-labs/go-ethereum/rlp"
+ 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 signer) to allow concurrent signers
+)
+
+// Clique proof-of-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 signer vanity
+ extraSeal = crypto.SignatureLength // Fixed number of extra-data suffix bytes reserved for signer seal
+
+ nonceAuthVote = hexutil.MustDecode("0xffffffffffffffff") // Magic nonce number to vote on adding a new signer
+ nonceDropVote = hexutil.MustDecode("0x0000000000000000") // Magic nonce number to vote on removing a signer.
+
+ 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
+)
+
+// 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 signers is requested for a block
+ // that is not part of the local blockchain.
+ errUnknownBlock = errors.New("unknown block")
+
+ // errInvalidCheckpointBeneficiary is returned if a checkpoint/epoch transition
+ // block has a beneficiary set to non-zeroes.
+ errInvalidCheckpointBeneficiary = errors.New("beneficiary in checkpoint block non-zero")
+
+ // errInvalidVote is returned if a nonce value is something else that the two
+ // allowed constants of 0x00..0 or 0xff..f.
+ errInvalidVote = errors.New("vote nonce not 0x00..0 or 0xff..f")
+
+ // errInvalidCheckpointVote is returned if a checkpoint/epoch transition block
+ // has a vote nonce set to non-zeroes.
+ errInvalidCheckpointVote = errors.New("vote nonce in checkpoint block non-zero")
+
+ // errMissingVanity is returned if a block's extra-data section is shorter than
+ // 32 bytes, which is required to store the signer 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")
+
+ // errExtraSigners is returned if non-checkpoint block contain signer data in
+ // their extra-data fields.
+ errExtraSigners = errors.New("non-checkpoint block contains extra signer list")
+
+ // errInvalidCheckpointSigners is returned if a checkpoint block contains an
+ // invalid list of signers (i.e. non divisible by 20 bytes).
+ errInvalidCheckpointSigners = errors.New("invalid signer list on checkpoint block")
+
+ // errMismatchingCheckpointSigners is returned if a checkpoint block contains a
+ // list of signers different than the one the local node calculated.
+ errMismatchingCheckpointSigners = errors.New("mismatching signer 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 signer.
+ 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")
+
+ // 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")
+
+ // errUnauthorizedSigner is returned if a header is signed by a non-authorized entity.
+ errUnauthorizedSigner = errors.New("unauthorized signer")
+
+ // 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")
+)
+
+// SignerFn is a signer callback function to request a header to be signed by a
+// backing account.
+type SignerFn func(accounts.Account, string, []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 signer common.Address
+ copy(signer[:], crypto.Keccak256(pubkey[1:])[12:])
+
+ sigcache.Add(hash, signer)
+ return signer, nil
+}
+
+// Clique is the proof-of-authority consensus engine proposed to support the
+// Ethereum testnet following the Ropsten attacks.
+type Clique struct {
+ config *params.CliqueConfig // 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
+
+ signer common.Address // Ethereum address of the signing key
+ signFn SignerFn // Signer function to authorize hashes with
+ lock sync.RWMutex // Protects the signer fields
+
+ // The fields below are for testing only
+ fakeDiff bool // Skip difficulty verifications
+}
+
+// New creates a Clique proof-of-authority consensus engine with the initial
+// signers set to the ones provided by the user.
+func New(config *params.CliqueConfig, db ethdb.Database) *Clique {
+ // Set any missing consensus parameters to their defaults
+ conf := *config
+ if conf.Epoch == 0 {
+ conf.Epoch = epochLength
+ }
+ // Allocate the snapshot caches and create the engine
+ recents, _ := lru.NewARC(inmemorySnapshots)
+ signatures, _ := lru.NewARC(inmemorySignatures)
+
+ return &Clique{
+ config: &conf,
+ db: db,
+ recents: recents,
+ signatures: signatures,
+ proposals: make(map[common.Address]bool),
+ }
+}
+
+// Author implements consensus.Engine, returning the Ethereum address recovered
+// from the signature in the header's extra-data section.
+func (c *Clique) Author(header *types.Header) (common.Address, error) {
+ return ecrecover(header, c.signatures)
+}
+
+// VerifyHeader checks whether a header conforms to the consensus rules.
+func (c *Clique) VerifyHeader(chain consensus.ChainReader, 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 *Clique) VerifyHeaders(chain consensus.ChainReader, 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 *Clique) verifyHeader(chain consensus.ChainReader, 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
+ }
+ // Checkpoint blocks need to enforce zero beneficiary
+ checkpoint := (number % c.config.Epoch) == 0
+ if checkpoint && header.Coinbase != (common.Address{}) {
+ return errInvalidCheckpointBeneficiary
+ }
+ // Nonces must be 0x00..0 or 0xff..f, zeroes enforced on checkpoints
+ if !bytes.Equal(header.Nonce[:], nonceAuthVote) && !bytes.Equal(header.Nonce[:], nonceDropVote) {
+ return errInvalidVote
+ }
+ if checkpoint && !bytes.Equal(header.Nonce[:], nonceDropVote) {
+ return errInvalidCheckpointVote
+ }
+ // Check that the extra-data contains both the vanity and signature
+ if len(header.Extra) < extraVanity {
+ return errMissingVanity
+ }
+ if len(header.Extra) < extraVanity+extraSeal {
+ return errMissingSignature
+ }
+ // Ensure that the extra-data contains a signer list on checkpoint, but none otherwise
+ signersBytes := len(header.Extra) - extraVanity - extraSeal
+ if !checkpoint && signersBytes != 0 {
+ return errExtraSigners
+ }
+ if checkpoint && signersBytes%common.AddressLength != 0 {
+ return errInvalidCheckpointSigners
+ }
+ // 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 {
+ if header.Difficulty == nil || (header.Difficulty.Cmp(diffInTurn) != 0 && header.Difficulty.Cmp(diffNoTurn) != 0) {
+ 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 *Clique) verifyCascadingFields(chain consensus.ChainReader, 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
+ }
+ // Ensure that the block's timestamp isn't too close to it's parent
+ 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
+ }
+ // 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
+ }
+ // If the block is a checkpoint block, verify the signer list
+ if number%c.config.Epoch == 0 {
+ signers := make([]byte, len(snap.Signers)*common.AddressLength)
+ for i, signer := range snap.signers() {
+ copy(signers[i*common.AddressLength:], signer[:])
+ }
+ extraSuffix := len(header.Extra) - extraSeal
+ if !bytes.Equal(header.Extra[extraVanity:extraSuffix], signers) {
+ return errMismatchingCheckpointSigners
+ }
+ }
+ // 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 *Clique) snapshot(chain consensus.ChainReader, 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.ImmutabilityThreshold || chain.GetHeaderByNumber(number-1) == nil)) {
+ checkpoint := chain.GetHeaderByNumber(number)
+ if checkpoint != nil {
+ hash := checkpoint.Hash()
+
+ signers := make([]common.Address, (len(checkpoint.Extra)-extraVanity-extraSeal)/common.AddressLength)
+ for i := 0; i < len(signers); i++ {
+ copy(signers[i][:], checkpoint.Extra[extraVanity+i*common.AddressLength:])
+ }
+ snap = newSnapshot(c.config, c.signatures, number, hash, signers)
+ 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)
+ 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 *Clique) 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 *Clique) VerifySeal(chain consensus.ChainReader, 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 *Clique) verifySeal(chain consensus.ChainReader, 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 signers
+ signer, err := ecrecover(header, c.signatures)
+ if err != nil {
+ return err
+ }
+ if _, ok := snap.Signers[signer]; !ok {
+ return errUnauthorizedSigner
+ }
+ for seen, recent := range snap.Recents {
+ if recent == signer {
+ // Signer is among recents, only fail if the current block doesn't shift it out
+ if limit := uint64(len(snap.Signers)/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 *Clique) Prepare(chain consensus.ChainReader, header *types.Header) error {
+ // If the block isn't a checkpoint, cast a random vote (good enough for now)
+ header.Coinbase = common.Address{}
+ header.Nonce = types.BlockNonce{}
+
+ number := header.Number.Uint64()
+ // Assemble the voting snapshot to check which votes make sense
+ snap, err := c.snapshot(chain, number-1, header.ParentHash, nil)
+ if err != nil {
+ return err
+ }
+ if number%c.config.Epoch != 0 {
+ c.lock.RLock()
+
+ // Gather all the proposals that make sense voting on
+ addresses := make([]common.Address, 0, len(c.proposals))
+ for address, authorize := range c.proposals {
+ if snap.validVote(address, authorize) {
+ addresses = append(addresses, address)
+ }
+ }
+ // If there's pending proposals, cast a vote on them
+ if len(addresses) > 0 {
+ header.Coinbase = addresses[rand.Intn(len(addresses))]
+ if c.proposals[header.Coinbase] {
+ copy(header.Nonce[:], nonceAuthVote)
+ } else {
+ copy(header.Nonce[:], nonceDropVote)
+ }
+ }
+ c.lock.RUnlock()
+ }
+ // Set the correct difficulty
+ header.Difficulty = CalcDifficulty(snap, c.signer)
+
+ // Ensure the extra data has all it's 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 {
+ for _, signer := range snap.signers() {
+ header.Extra = append(header.Extra, signer[:]...)
+ }
+ }
+ 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 *Clique) Finalize(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header) {
+ // 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)
+}
+
+// FinalizeAndAssemble implements consensus.Engine, ensuring no uncles are set,
+// nor block rewards given, and returns the final block.
+func (c *Clique) FinalizeAndAssemble(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
+ // 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, nil), nil
+}
+
+// Authorize injects a private key into the consensus engine to mint new blocks
+// with.
+func (c *Clique) Authorize(signer common.Address, signFn SignerFn) {
+ c.lock.Lock()
+ defer c.lock.Unlock()
+
+ c.signer = signer
+ c.signFn = signFn
+}
+
+// Seal implements consensus.Engine, attempting to create a sealed block using
+// the local signing credentials.
+func (c *Clique) Seal(chain consensus.ChainReader, 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 signer fields for the entire sealing procedure
+ c.lock.RLock()
+ signer, signFn := c.signer, 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.Signers[signer]; !authorized {
+ return errUnauthorizedSigner
+ }
+ // If we're amongst the recent signers, wait for the next block
+ for seen, recent := range snap.Recents {
+ if recent == signer {
+ // Signer is among recents, only wait if the current block doesn't shift it out
+ if limit := uint64(len(snap.Signers)/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.Signers)/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: signer}, accounts.MimetypeClique, CliqueRLP(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 based on the previous blocks in the chain and the
+// current signer.
+func (c *Clique) CalcDifficulty(chain consensus.ChainReader, 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.signer)
+}
+
+// CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
+// that a new block should have based on the previous blocks in the chain and the
+// current signer.
+func CalcDifficulty(snap *Snapshot, signer common.Address) *big.Int {
+ if snap.inturn(snap.Number+1, signer) {
+ 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 *Clique) SealHash(header *types.Header) common.Hash {
+ return SealHash(header)
+}
+
+// Close implements consensus.Engine. It's a noop for clique as there are no background threads.
+func (c *Clique) Close() error {
+ return nil
+}
+
+// APIs implements consensus.Engine, returning the user facing RPC API to allow
+// controlling the signer voting.
+func (c *Clique) APIs(chain consensus.ChainReader) []rpc.API {
+ return []rpc.API{{
+ Namespace: "clique",
+ Version: "1.0",
+ Service: &API{chain: chain, clique: 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
+}
+
+// CliqueRLP returns the rlp bytes which needs to be signed for the proof-of-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 CliqueRLP(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,
+ header.Root,
+ header.TxHash,
+ header.ReceiptHash,
+ header.Bloom,
+ header.Difficulty,
+ header.Number,
+ header.GasLimit,
+ header.GasUsed,
+ header.Time,
+ header.Extra[:len(header.Extra)-crypto.SignatureLength], // Yes, this will panic if extra is too short
+ header.MixDigest,
+ header.Nonce,
+ })
+ if err != nil {
+ panic("can't encode: " + err.Error())
+ }
+}
+
+func (c *Clique) ExtraStateChange(_ *types.Block, _ *state.StateDB) error {
+ return nil
+}
diff --git a/consensus/clique/snapshot.go b/consensus/clique/snapshot.go
new file mode 100644
index 0000000..6660c0f
--- /dev/null
+++ b/consensus/clique/snapshot.go
@@ -0,0 +1,326 @@
+// 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 clique
+
+import (
+ "bytes"
+ "encoding/json"
+ "sort"
+ "time"
+
+ "github.com/ava-labs/coreth/core/types"
+ "github.com/ava-labs/coreth/params"
+ "github.com/ava-labs/go-ethereum/common"
+ "github.com/ava-labs/go-ethereum/ethdb"
+ "github.com/ava-labs/go-ethereum/log"
+ lru "github.com/hashicorp/golang-lru"
+)
+
+// Vote represents a single vote that an authorized signer made to modify the
+// list of authorizations.
+type Vote struct {
+ Signer common.Address `json:"signer"` // Authorized signer that cast this vote
+ Block uint64 `json:"block"` // Block number the vote was cast in (expire old votes)
+ Address common.Address `json:"address"` // Account being voted on to change its authorization
+ Authorize bool `json:"authorize"` // Whether to authorize or deauthorize the voted account
+}
+
+// Tally is a simple vote tally to keep the current score of votes. Votes that
+// go against the proposal aren't counted since it's equivalent to not voting.
+type Tally struct {
+ Authorize bool `json:"authorize"` // Whether the vote is about authorizing or kicking someone
+ Votes int `json:"votes"` // Number of votes until now wanting to pass the proposal
+}
+
+// Snapshot is the state of the authorization voting at a given point in time.
+type Snapshot struct {
+ config *params.CliqueConfig // Consensus engine parameters to fine tune behavior
+ sigcache *lru.ARCCache // Cache of recent block signatures to speed up ecrecover
+
+ Number uint64 `json:"number"` // Block number where the snapshot was created
+ Hash common.Hash `json:"hash"` // Block hash where the snapshot was created
+ Signers map[common.Address]struct{} `json:"signers"` // Set of authorized signers at this moment
+ Recents map[uint64]common.Address `json:"recents"` // Set of recent signers for spam protections
+ Votes []*Vote `json:"votes"` // List of votes cast in chronological order
+ Tally map[common.Address]Tally `json:"tally"` // Current vote tally to avoid recalculating
+}
+
+// signersAscending implements the sort interface to allow sorting a list of addresses
+type signersAscending []common.Address
+
+func (s signersAscending) Len() int { return len(s) }
+func (s signersAscending) Less(i, j int) bool { return bytes.Compare(s[i][:], s[j][:]) < 0 }
+func (s signersAscending) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+
+// newSnapshot creates a new snapshot with the specified startup parameters. This
+// method does not initialize the set of recent signers, so only ever use if for
+// the genesis block.
+func newSnapshot(config *params.CliqueConfig, sigcache *lru.ARCCache, number uint64, hash common.Hash, signers []common.Address) *Snapshot {
+ snap := &Snapshot{
+ config: config,
+ sigcache: sigcache,
+ Number: number,
+ Hash: hash,
+ Signers: make(map[common.Address]struct{}),
+ Recents: make(map[uint64]common.Address),
+ Tally: make(map[common.Address]Tally),
+ }
+ for _, signer := range signers {
+ snap.Signers[signer] = struct{}{}
+ }
+ return snap
+}
+
+// loadSnapshot loads an existing snapshot from the database.
+func loadSnapshot(config *params.CliqueConfig, sigcache *lru.ARCCache, db ethdb.Database, hash common.Hash) (*Snapshot, error) {
+ blob, err := db.Get(append([]byte("clique-"), hash[:]...))
+ if err != nil {
+ return nil, err
+ }
+ snap := new(Snapshot)
+ if err := json.Unmarshal(blob, snap); err != nil {
+ return nil, err
+ }
+ snap.config = config
+ snap.sigcache = sigcache
+
+ return snap, nil
+}
+
+// store inserts the snapshot into the database.
+func (s *Snapshot) store(db ethdb.Database) error {
+ blob, err := json.Marshal(s)
+ if err != nil {
+ return err
+ }
+ return db.Put(append([]byte("clique-"), s.Hash[:]...), blob)
+}
+
+// copy creates a deep copy of the snapshot, though not the individual votes.
+func (s *Snapshot) copy() *Snapshot {
+ cpy := &Snapshot{
+ config: s.config,
+ sigcache: s.sigcache,
+ Number: s.Number,
+ Hash: s.Hash,
+ Signers: make(map[common.Address]struct{}),
+ Recents: make(map[uint64]common.Address),
+ Votes: make([]*Vote, len(s.Votes)),
+ Tally: make(map[common.Address]Tally),
+ }
+ for signer := range s.Signers {
+ cpy.Signers[signer] = struct{}{}
+ }
+ for block, signer := range s.Recents {
+ cpy.Recents[block] = signer
+ }
+ for address, tally := range s.Tally {
+ cpy.Tally[address] = tally
+ }
+ copy(cpy.Votes, s.Votes)
+
+ return cpy
+}
+
+// validVote returns whether it makes sense to cast the specified vote in the
+// given snapshot context (e.g. don't try to add an already authorized signer).
+func (s *Snapshot) validVote(address common.Address, authorize bool) bool {
+ _, signer := s.Signers[address]
+ return (signer && !authorize) || (!signer && authorize)
+}
+
+// cast adds a new vote into the tally.
+func (s *Snapshot) cast(address common.Address, authorize bool) bool {
+ // Ensure the vote is meaningful
+ if !s.validVote(address, authorize) {
+ return false
+ }
+ // Cast the vote into an existing or new tally
+ if old, ok := s.Tally[address]; ok {
+ old.Votes++
+ s.Tally[address] = old
+ } else {
+ s.Tally[address] = Tally{Authorize: authorize, Votes: 1}
+ }
+ return true
+}
+
+// uncast removes a previously cast vote from the tally.
+func (s *Snapshot) uncast(address common.Address, authorize bool) bool {
+ // If there's no tally, it's a dangling vote, just drop
+ tally, ok := s.Tally[address]
+ if !ok {
+ return false
+ }
+ // Ensure we only revert counted votes
+ if tally.Authorize != authorize {
+ return false
+ }
+ // Otherwise revert the vote
+ if tally.Votes > 1 {
+ tally.Votes--
+ s.Tally[address] = tally
+ } else {
+ delete(s.Tally, address)
+ }
+ return true
+}
+
+// apply creates a new authorization snapshot by applying the given headers to
+// the original one.
+func (s *Snapshot) apply(headers []*types.Header) (*Snapshot, error) {
+ // Allow passing in no headers for cleaner code
+ if len(headers) == 0 {
+ return s, nil
+ }
+ // Sanity check that the headers can be applied
+ for i := 0; i < len(headers)-1; i++ {
+ if headers[i+1].Number.Uint64() != headers[i].Number.Uint64()+1 {
+ return nil, errInvalidVotingChain
+ }
+ }
+ if headers[0].Number.Uint64() != s.Number+1 {
+ return nil, errInvalidVotingChain
+ }
+ // Iterate through the headers and create a new snapshot
+ snap := s.copy()
+
+ var (
+ start = time.Now()
+ logged = time.Now()
+ )
+ for i, header := range headers {
+ // Remove any votes on checkpoint blocks
+ number := header.Number.Uint64()
+ if number%s.config.Epoch == 0 {
+ snap.Votes = nil
+ snap.Tally = make(map[common.Address]Tally)
+ }
+ // Delete the oldest signer from the recent list to allow it signing again
+ if limit := uint64(len(snap.Signers)/2 + 1); number >= limit {
+ delete(snap.Recents, number-limit)
+ }
+ // Resolve the authorization key and check against signers
+ signer, err := ecrecover(header, s.sigcache)
+ if err != nil {
+ return nil, err
+ }
+ if _, ok := snap.Signers[signer]; !ok {
+ return nil, errUnauthorizedSigner
+ }
+ for _, recent := range snap.Recents {
+ if recent == signer {
+ return nil, errRecentlySigned
+ }
+ }
+ snap.Recents[number] = signer
+
+ // Header authorized, discard any previous votes from the signer
+ for i, vote := range snap.Votes {
+ if vote.Signer == signer && vote.Address == header.Coinbase {
+ // Uncast the vote from the cached tally
+ snap.uncast(vote.Address, vote.Authorize)
+
+ // Uncast the vote from the chronological list
+ snap.Votes = append(snap.Votes[:i], snap.Votes[i+1:]...)
+ break // only one vote allowed
+ }
+ }
+ // Tally up the new vote from the signer
+ var authorize bool
+ switch {
+ case bytes.Equal(header.Nonce[:], nonceAuthVote):
+ authorize = true
+ case bytes.Equal(header.Nonce[:], nonceDropVote):
+ authorize = false
+ default:
+ return nil, errInvalidVote
+ }
+ if snap.cast(header.Coinbase, authorize) {
+ snap.Votes = append(snap.Votes, &Vote{
+ Signer: signer,
+ Block: number,
+ Address: header.Coinbase,
+ Authorize: authorize,
+ })
+ }
+ // If the vote passed, update the list of signers
+ if tally := snap.Tally[header.Coinbase]; tally.Votes > len(snap.Signers)/2 {
+ if tally.Authorize {
+ snap.Signers[header.Coinbase] = struct{}{}
+ } else {
+ delete(snap.Signers, header.Coinbase)
+
+ // Signer list shrunk, delete any leftover recent caches
+ if limit := uint64(len(snap.Signers)/2 + 1); number >= limit {
+ delete(snap.Recents, number-limit)
+ }
+ // Discard any previous votes the deauthorized signer cast
+ for i := 0; i < len(snap.Votes); i++ {
+ if snap.Votes[i].Signer == header.Coinbase {
+ // Uncast the vote from the cached tally
+ snap.uncast(snap.Votes[i].Address, snap.Votes[i].Authorize)
+
+ // Uncast the vote from the chronological list
+ snap.Votes = append(snap.Votes[:i], snap.Votes[i+1:]...)
+
+ i--
+ }
+ }
+ }
+ // Discard any previous votes around the just changed account
+ for i := 0; i < len(snap.Votes); i++ {
+ if snap.Votes[i].Address == header.Coinbase {
+ snap.Votes = append(snap.Votes[:i], snap.Votes[i+1:]...)
+ i--
+ }
+ }
+ delete(snap.Tally, header.Coinbase)
+ }
+ // If we're taking too much time (ecrecover), notify the user once a while
+ if time.Since(logged) > 8*time.Second {
+ log.Info("Reconstructing voting history", "processed", i, "total", len(headers), "elapsed", common.PrettyDuration(time.Since(start)))
+ logged = time.Now()
+ }
+ }
+ if time.Since(start) > 8*time.Second {
+ log.Info("Reconstructed voting history", "processed", len(headers), "elapsed", common.PrettyDuration(time.Since(start)))
+ }
+ snap.Number += uint64(len(headers))
+ snap.Hash = headers[len(headers)-1].Hash()
+
+ return snap, nil
+}
+
+// signers retrieves the list of authorized signers in ascending order.
+func (s *Snapshot) signers() []common.Address {
+ sigs := make([]common.Address, 0, len(s.Signers))
+ for sig := range s.Signers {
+ sigs = append(sigs, sig)
+ }
+ sort.Sort(signersAscending(sigs))
+ return sigs
+}
+
+// inturn returns if a signer at a given block height is in-turn or not.
+func (s *Snapshot) inturn(number uint64, signer common.Address) bool {
+ signers, offset := s.signers(), 0
+ for offset < len(signers) && signers[offset] != signer {
+ offset++
+ }
+ return (number % uint64(len(signers))) == uint64(offset)
+}
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