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# Nimbus
# Copyright (c) 2018 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
# http://www.apache.org/licenses/LICENSE-2.0)
# * MIT license ([LICENSE-MIT](LICENSE-MIT) or
# http://opensource.org/licenses/MIT)
# at your option. This file may not be copied, modified, or distributed except
# according to those terms.
##
## EIP-225 Clique PoA Consensus Protocol
## =====================================
##
## For details see
## `EIP-225 <https://github.com/ethereum/EIPs/blob/master/EIPS/eip-225.md>`_
## and
## `go-ethereum <https://github.com/ethereum/EIPs/blob/master/EIPS/eip-225.md>`_
##
import
../constants,
../db/[db_chain, state_db],
../utils,
./clique/[clique_cfg, clique_defs, clique_utils, ec_recover, recent_snaps],
chronicles,
chronos,
eth/[common, keys, rlp],
nimcrypto,
random,
sequtils,
strformat,
tables,
times
export
clique_cfg,
clique_defs
type
# clique/clique.go(142): type SignerFn func(signer [..]
CliqueSignerFn* = ## Hashes and signs the data to be signed by
## a backing account
proc(signer: EthAddress;
message: openArray[byte]): Result[Hash256,cstring] {.gcsafe.}
Proposals = Table[EthAddress,bool]
# clique/clique.go(172): type Clique struct { [..]
Clique* = object ## Clique is the proof-of-authority consensus engine
## proposed to support the Ethereum testnet following
## the Ropsten attacks.
cfg: CliqueCfg ## Consensus engine parameters to fine tune behaviour
recents: RecentSnaps ## Snapshots for recent block to speed up reorgs
# signatures => see CliqueCfg
proposals: Proposals ## Current list of proposals we are pushing
signer: EthAddress ## Ethereum address of the signing key
signFn: CliqueSignerFn ## Signer function to authorize hashes with
lock: AsyncLock ## Protects the signer fields
fakeDiff: bool ## Testing only: skip difficulty verifications
stopSealReq: bool ## Stop running `seal()` function
stopVHeaderReq: bool ## Stop running `verifyHeader()` function
{.push raises: [Defect,CatchableError].}
logScope:
topics = "clique PoA"
# ------------------------------------------------------------------------------
# Private Helpers
# ------------------------------------------------------------------------------
template doExclusively(c: var Clique; action: untyped) =
waitFor c.lock.acquire
action
c.lock.release
# ------------------------------------------------------------------------------
# Private functions
# ------------------------------------------------------------------------------
# clique/clique.go(145): func ecrecover(header [..]
proc ecrecover(c: var Clique;
header: BlockHeader): Result[EthAddress,CliqueError] =
## ecrecover extracts the Ethereum account address from a signed header.
c.cfg.signatures.getEcRecover(header)
# clique/clique.go(369): func (c *Clique) snapshot(chain [..]
proc snapshot(c: var Clique; blockNumber: BlockNumber; hash: Hash256;
parents: openArray[Blockheader]): Result[Snapshot,CliqueError] =
## snapshot retrieves the authorization snapshot at a given point in time.
c.recents.getRecentSnaps:
RecentArgs(blockHash: hash,
blockNumber: blockNumber,
parents: toSeq(parents))
# clique/clique.go(463): func (c *Clique) verifySeal(chain [..]
proc verifySeal(c: var Clique; header: BlockHeader;
parents: openArray[BlockHeader]): CliqueResult =
## Check 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.
# Verifying the genesis block is not supported
if header.blockNumber.isZero:
return err((errUnknownBlock,""))
# Retrieve the snapshot needed to verify this header and cache it
var snap = c.snapshot(header.blockNumber-1, header.parentHash, parents)
if snap.isErr:
return err(snap.error)
# Resolve the authorization key and check against signers
let signer = c.ecrecover(header)
if signer.isErr:
return err(signer.error)
if not snap.value.isSigner(signer.value):
return err((errUnauthorizedSigner,""))
let seen = snap.value.recent(signer.value)
if seen.isOk:
# Signer is among recents, only fail if the current block does not
# shift it out
if header.blockNumber - snap.value.signersThreshold.u256 < seen.value:
return err((errRecentlySigned,""))
# Ensure that the difficulty corresponds to the turn-ness of the signer
if not c.fakeDiff:
if snap.value.inTurn(header.blockNumber, signer.value):
if header.difficulty != DIFF_INTURN:
return err((errWrongDifficulty,""))
else:
if header.difficulty != DIFF_NOTURN:
return err((errWrongDifficulty,""))
return ok()
# clique/clique.go(314): func (c *Clique) verifyCascadingFields(chain [..]
proc verifyCascadingFields(c: var Clique; header: BlockHeader;
parents: openArray[BlockHeader]): CliqueResult =
## Verify 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.
# The genesis block is the always valid dead-end
if header.blockNumber.isZero:
return err((errZeroBlockNumberRejected,""))
# Ensure that the block's timestamp isn't too close to its parent
var parent: BlockHeader
if 0 < parents.len:
parent = parents[^1]
else:
let rc = c.cfg.dbChain.getBlockHeaderResult(header.blockNumber-1)
if rc.isErr:
return err((errUnknownAncestor,""))
parent = rc.value
if parent.blockNumber != header.blockNumber-1 or
parent.hash != header.parentHash:
return err((errUnknownAncestor,""))
if header.timestamp < parent.timestamp + c.cfg.period:
return err((errInvalidTimestamp,""))
# Verify that the gasUsed is <= gasLimit
if header.gasLimit < header.gasUsed:
return err((errCliqueExceedsGasLimit,
&"invalid gasUsed: have {header.gasUsed}, " &
&"gasLimit {header.gasLimit}"))
if not c.cfg.dbChain.config.isLondonOrLater(header.blockNumber):
# Verify BaseFee not present before EIP-1559 fork.
if not header.baseFee.isZero:
return err((errCliqueUnsupportedBaseFee,
"invalid baseFee before London fork: have " &
&"{header.baseFee}, want <0>"))
let rc = c.cfg.dbChain.validateGasLimit(header)
if rc.isErr:
return err(rc.error)
else:
let rc = c.cfg.dbChain.config.verify1559Header(parent = parent,
header = header)
if rc.isErr:
return err(rc.error)
# Retrieve the snapshot needed to verify this header and cache it
var snap = c.snapshot(header.blockNumber-1, header.parentHash, parents)
if snap.isErr:
return err(snap.error)
# If the block is a checkpoint block, verify the signer list
if (header.blockNumber mod c.cfg.epoch.u256) == 0:
let
signersList = snap.value.signers
extraList = header.extraData.extraDataSigners
if signersList != extraList:
return err((errMismatchingCheckpointSigners,""))
# All basic checks passed, verify the seal and return
return c.verifySeal(header, parents)
# clique/clique.go(246): func (c *Clique) verifyHeader(chain [..]
proc verifyHeader(c: var Clique; header: BlockHeader;
parents: openArray[BlockHeader]): CliqueResult =
## Check 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.
if header.blockNumber.isZero:
return err((errUnknownBlock,""))
# Don't waste time checking blocks from the future
if getTime() < header.timestamp:
return err((errFutureBlock,""))
# Checkpoint blocks need to enforce zero beneficiary
let isCheckPoint = (header.blockNumber mod c.cfg.epoch.u256) == 0
if isCheckPoint and not header.coinbase.isZero:
return err((errInvalidCheckpointBeneficiary,""))
# Nonces must be 0x00..0 or 0xff..f, zeroes enforced on checkpoints
if header.nonce != NONCE_AUTH and header.nonce != NONCE_DROP:
return err((errInvalidVote,""))
if isCheckPoint and header.nonce != NONCE_DROP:
return err((errInvalidCheckpointVote,""))
# Check that the extra-data contains both the vanity and signature
if header.extraData.len < EXTRA_VANITY:
return err((errMissingVanity,""))
if header.extraData.len < EXTRA_VANITY + EXTRA_SEAL:
return err((errMissingSignature,""))
# Ensure that the extra-data contains a signer list on checkpoint,
# but none otherwise
let signersBytes = header.extraData.len - EXTRA_VANITY - EXTRA_SEAL
if not isCheckPoint and signersBytes != 0:
return err((errExtraSigners,""))
if isCheckPoint and (signersBytes mod EthAddress.len) != 0:
return err((errInvalidCheckpointSigners,""))
# Ensure that the mix digest is zero as we do not have fork protection
# currently
if not header.mixDigest.isZero:
return err((errInvalidMixDigest,""))
# Ensure that the block does not contain any uncles which are meaningless
# in PoA
if header.ommersHash != EMPTY_UNCLE_HASH:
return err((errInvalidUncleHash,""))
# Ensure that the block's difficulty is meaningful (may not be correct at
# this point)
if not header.blockNumber.isZero:
if header.difficulty.isZero or
(header.difficulty != DIFF_INTURN and
header.difficulty != DIFF_NOTURN):
return err((errInvalidDifficulty,""))
# verify that the gas limit is <= 2^63-1
when header.gasLimit.typeof isnot int64:
if int64.high < header.gasLimit:
return err((errCliqueExceedsGasLimit,
&"invalid gasLimit: have {header.gasLimit}, must be int64"))
# If all checks passed, validate any special fields for hard forks
let rc = c.cfg.dbChain.config.verifyForkHashes(header)
if rc.isErr:
return err(rc.error)
# All basic checks passed, verify cascading fields
return c.verifyCascadingFields(header, parents)
# clique/clique.go(681): func calcDifficulty(snap [..]
proc calcDifficulty(snap: var Snapshot; signer: EthAddress): DifficultyInt =
if snap.inTurn(snap.blockNumber + 1, signer):
DIFF_INTURN
else:
DIFF_NOTURN
# ------------------------------------------------------------------------------
# Public functions
# ------------------------------------------------------------------------------
# clique/clique.go(191): func New(config [..]
proc initClique*(c: var Clique; cfg: CliqueCfg; testMode = false) =
## Initialiser for Clique proof-of-authority consensus engine with the
## initial signers set to the ones provided by the user.
c.cfg = cfg
c.recents = initRecentSnaps(cfg)
c.proposals = initTable[EthAddress,bool]()
c.lock = newAsyncLock()
c.fakeDiff = testMode
proc initClique*(cfg: CliqueCfg; testMode = false): Clique =
result.initClique(cfg, testMode)
# clique/clique.go(212): func (c *Clique) Author(header [..]
proc author*(c: var Clique;
header: BlockHeader): Result[EthAddress,CliqueError] =
## For the Consensus Engine, `author()` retrieves the Ethereum address of the
## account that minted the given block, which may be different from the
## header's coinbase if a consensus engine is based on signatures.
##
## This implementation returns the Ethereum address recovered from the
## signature in the header's extra-data section.
c.ecrecover(header)
# clique/clique.go(217): func (c *Clique) VerifyHeader(chain [..]
proc verifyHeader*(c: var Clique; header: BlockHeader): CliqueResult =
## For the Consensus Engine, `verifyHeader()` checks whether a header
## conforms to the consensus rules of a given engine. Verifying the seal
## may be done optionally here, or explicitly via the `verifySeal()` method.
##
## This implementation checks whether a header conforms to the consensus
## rules.
c.verifyHeader(header, @[])
# clique/clique.go(224): func (c *Clique) VerifyHeader(chain [..]
proc verifyHeaders*(c: var Clique; headers: openArray[BlockHeader]):
Future[seq[CliqueResult]] {.async,gcsafe.} =
## For the Consensus Engine, `verifyHeader()` s similar to VerifyHeader, but
## verifies a batch of headers concurrently. This method is accompanied
## by a `stopVerifyHeader()` method that can abort the operations.
##
## This implementation checks whether a header conforms to the consensus
## rules. It verifies a batch of headers. If running in the background,
## the process can be stopped by calling the `stopVerifyHeader()` function.
c.doExclusively:
c.stopVHeaderReq = false
for n in 0 ..< headers.len:
c.doExclusively:
let isStopRequest = c.stopVHeaderReq
if isStopRequest:
result.add cliqueResultErr((errCliqueStopped,""))
break ;
result.add c.verifyHeader(headers[n], headers[0 ..< n])
c.doExclusively:
c.stopVHeaderReq = false
proc stopVerifyHeader*(c: var Clique): bool {.discardable.} =
## Activate the stop flag for running `verifyHeader()` function.
## Returns `true` if the stop flag could be activated.
c.doExclusively:
if not c.stopVHeaderReq:
c.stopVHeaderReq = true
result = true
# clique/clique.go(450): func (c *Clique) VerifyUncles(chain [..]
proc verifyUncles*(c: var Clique; ethBlock: EthBlock): CliqueResult =
## For the Consensus Engine, `verifyUncles()` verifies that the given
## block's uncles conform to the consensus rules of a given engine.
##
## This implementation always returns an error for existing uncles as this
## consensus mechanism doesn't permit uncles.
if 0 < ethBlock.uncles.len:
return err((errCliqueUnclesNotAllowed,""))
result = ok()
# clique/clique.go(506): func (c *Clique) Prepare(chain [..]
proc prepare*(c: var Clique; header: var BlockHeader): CliqueResult =
## For the Consensus Engine, `prepare()` initializes the consensus fields
## of a block header according to the rules of a particular engine. The
## changes are executed inline.
##
## This implementation prepares all the consensus fields of the header for
## running the transactions on top.
# If the block isn't a checkpoint, cast a random vote (good enough for now)
header.coinbase.reset
header.nonce.reset
# Assemble the voting snapshot to check which votes make sense
var snap = c.snapshot(header.blockNumber-1, header.parentHash, @[])
if snap.isErr:
return err(snap.error)
if (header.blockNumber mod c.cfg.epoch) != 0:
c.doExclusively:
# Gather all the proposals that make sense voting on
var addresses: seq[EthAddress]
for (address,authorize) in c.proposals.pairs:
if snap.value.validVote(address, authorize):
addresses.add address
# If there's pending proposals, cast a vote on them
if 0 < addresses.len:
header.coinbase = addresses[c.cfg.prng.rand(addresses.len-1)]
header.nonce = if header.coinbase in c.proposals: NONCE_AUTH
else: NONCE_DROP
# Set the correct difficulty
header.difficulty = snap.value.calcDifficulty(c.signer)
# Ensure the extra data has all its components
header.extraData.setLen(EXTRA_VANITY)
if (header.blockNumber mod c.cfg.epoch) == 0:
header.extraData.add snap.value.signers.mapIt(toSeq(it)).concat
header.extraData.add 0.byte.repeat(EXTRA_SEAL)
# Mix digest is reserved for now, set to empty
header.mixDigest.reset
# Ensure the timestamp has the correct delay
let parent = c.cfg.dbChain.getBlockHeaderResult(header.blockNumber-1)
if parent.isErr:
return err((errUnknownAncestor,""))
header.timestamp = parent.value.timestamp + c.cfg.period
if header.timestamp < getTime():
header.timestamp = getTime()
return ok()
# clique/clique.go(571): func (c *Clique) Finalize(chain [..]
proc finalize*(c: var Clique; header: BlockHeader; db: AccountStateDB) =
## For the Consensus Engine, `finalize()` runs any post-transaction state
## modifications (e.g. block rewards) but does not assemble the block.
##
## Note: The block header and state database might be updated to reflect any
## consensus rules that happen at finalization (e.g. block rewards).
##
## Not implemented here, raises `AssertionDefect`
raiseAssert "Not implemented"
#
# ## This implementation ensures no uncles are set, nor block rewards given.
# # No block rewards in PoA, so the state remains as is and uncles are dropped
# let deleteEmptyObjectsOk = c.cfg.config.eip158block <= header.blockNumber
# header.stateRoot = db.intermediateRoot(deleteEmptyObjectsOk)
# header.ommersHash = EMPTY_UNCLE_HASH
# clique/clique.go(579): func (c *Clique) FinalizeAndAssemble(chain [..]
proc finalizeAndAssemble*(c: var Clique; header: BlockHeader;
db: AccountStateDB; txs: openArray[Transaction];
receipts: openArray[Receipt]):
Result[EthBlock,CliqueError] =
## For the Consensus Engine, `finalizeAndAssemble()` runs any
## post-transaction state modifications (e.g. block rewards) and assembles
## the final block.
##
## Note: The block header and state database might be updated to reflect any
## consensus rules that happen at finalization (e.g. block rewards).
##
## Not implemented here, raises `AssertionDefect`
raiseAssert "Not implemented"
# ## Ensuring no uncles are set, nor block rewards given, and returns the
# ## final block.
#
# # Finalize block
# c.finalize(header, state, txs, uncles)
#
# # Assemble and return the final block for sealing
# return types.NewBlock(header, txs, nil, receipts,
# trie.NewStackTrie(nil)), nil
# clique/clique.go(589): func (c *Clique) Authorize(signer [..]
proc authorize*(c: var Clique; signer: EthAddress; signFn: CliqueSignerFn) =
## Injects private key into the consensus engine to mint new blocks with.
c.doExclusively:
c.signer = signer
c.signFn = signFn
# clique/clique.go(724): func CliqueRLP(header [..]
proc cliqueRlp*(header: BlockHeader): seq[byte] =
## 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.
header.encodeSealHeader
# clique/clique.go(688): func SealHash(header *types.Header) common.Hash {
proc sealHash*(header: BlockHeader): Hash256 =
## For the Consensus Engine, `sealHash()` returns the hash of a block prior
## to it being sealed.
##
## This implementation returns the hash of a block prior to it being sealed.
header.hashSealHeader
# clique/clique.go(599): func (c *Clique) Seal(chain [..]
proc seal*(c: var Clique; ethBlock: EthBlock):
Future[Result[EthBlock,CliqueError]] {.async,gcsafe.} =
## For the Consensus Engine, `seal()` generates a new sealing request for
## the given input block and pushes the result into the given channel.
##
## Note, the method returns immediately and will send the result async. More
## than one result may also be returned depending on the consensus algorithm.
##
## This implementation attempts to create a sealed block using the local
## signing credentials. If running in the background, the process can be
## stopped by calling the `stopSeal()` function.
c.doExclusively:
c.stopSealReq = false
var header = ethBlock.header
# Sealing the genesis block is not supported
if header.blockNumber.isZero:
return err((errUnknownBlock,""))
# For 0-period chains, refuse to seal empty blocks (no reward but would spin
# sealing)
if c.cfg.period.isZero and ethBlock.txs.len == 0:
info $nilCliqueSealNoBlockYet
return err((nilCliqueSealNoBlockYet,""))
# Don't hold the signer fields for the entire sealing procedure
c.doExclusively:
let
signer = c.signer
signFn = c.signFn
# Bail out if we're unauthorized to sign a block
var snap = c.snapshot(header.blockNumber-1, header.parentHash, @[])
if snap.isErr:
return err(snap.error)
if not snap.value.isSigner(signer):
return err((errUnauthorizedSigner,""))
# If we're amongst the recent signers, wait for the next block
let seen = snap.value.recent(signer)
if seen.isOk:
# Signer is among recents, only wait if the current block does not
# shift it out
if header.blockNumber < seen.value + snap.value.signersThreshold.u256:
info $nilCliqueSealSignedRecently
return err((nilCliqueSealSignedRecently,""))
# Sweet, the protocol permits us to sign the block, wait for our time
var delay = header.timestamp - getTime()
if header.difficulty == DIFF_NOTURN:
# It's not our turn explicitly to sign, delay it a bit
let wiggle = snap.value.signersThreshold.int64 * WIGGLE_TIME
# Kludge for limited rand() argument range
if wiggle.inSeconds < (int.high div 1000).int64:
let rndWiggleMs = c.cfg.prng.rand(wiggle.inMilliSeconds.int)
delay += initDuration(milliseconds = rndWiggleMs)
else:
let rndWiggleSec = c.cfg.prng.rand((wiggle.inSeconds and int.high).int)
delay += initDuration(seconds = rndWiggleSec)
trace "Out-of-turn signing requested",
wiggle = $wiggle
# Sign all the things!
let sigHash = signFn(signer,header.cliqueRlp)
if sigHash.isErr:
return err((errCliqueSealSigFn,$sigHash.error))
let extraLen = header.extraData.len
if EXTRA_SEAL < extraLen:
header.extraData.setLen(extraLen - EXTRA_SEAL)
header.extraData.add sigHash.value.data
# Wait until sealing is terminated or delay timeout.
trace "Waiting for slot to sign and propagate",
delay = $delay
# FIXME: double check
let timeOutTime = getTime() + delay
while getTime() < timeOutTime:
c.doExclusively:
let isStopRequest = c.stopVHeaderReq
if isStopRequest:
warn "Sealing result is not read by miner",
sealhash = sealHash(header)
return err((errCliqueStopped,""))
poll()
c.doExclusively:
c.stopSealReq = false
return ok(ethBlock.withHeader(header))
proc stopSeal*(c: var Clique): bool {.discardable.} =
## Activate the stop flag for running `seal()` function.
## Returns `true` if the stop flag could be activated.
c.doExclusively:
if not c.stopSealReq:
c.stopSealReq = true
result =true
# clique/clique.go(673): func (c *Clique) CalcDifficulty(chain [..]
proc calcDifficulty(c: var Clique;
parent: BlockHeader): Result[DifficultyInt,CliqueError] =
## For the Consensus Engine, `calcDifficulty()` is the difficulty adjustment
## algorithm. It returns the difficulty that a new block should have.
##
## This implementation returns the difficulty that a new block should have:
## * DIFF_NOTURN(2) if BLOCK_NUMBER % SIGNER_COUNT != SIGNER_INDEX
## * DIFF_INTURN(1) if BLOCK_NUMBER % SIGNER_COUNT == SIGNER_INDEX
var snap = c.snapshot(parent.blockNumber, parent.blockHash, @[])
if snap.isErr:
return err(snap.error)
return ok(snap.value.calcDifficulty(c.signer))
# # clique/clique.go(710): func (c *Clique) SealHash(header [..]
# proc sealHash(c: var Clique; header: BlockHeader): Hash256 =
# ## SealHash returns the hash of a block prior to it being sealed.
# header.encodeSigHeader.keccakHash
# ------------------------------------------------------------------------------
# Test interface
# ------------------------------------------------------------------------------
proc snapshotInternal*(c: var Clique; number: BlockNumber; hash: Hash256;
parent: openArray[Blockheader]): auto =
c.snapshot(number, hash, parent)
proc cfgInternal*(c: var Clique): auto =
c.cfg
proc pp*(rc: var Result[Snapshot,CliqueError]; indent = 0): string =
if rc.isOk:
rc.value.pp(indent)
else:
"(error: " & rc.error.pp & ")"
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------
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