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# beacon_chain
# Copyright (c) 2019-2022 Status Research & Development GmbH
# Licensed and distributed under either of
# * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
# * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.
{.push raises: [Defect].}
import
# Status
chronicles, chronos, metrics,
stew/results,
# Internals
../spec/datatypes/[phase0, altair, bellatrix],
../spec/[
beaconstate, state_transition_block, forks, helpers, network, signatures],
../consensus_object_pools/[
attestation_pool, blockchain_dag, block_quarantine, exit_pool, spec_cache,
sync_committee_msg_pool],
".."/[beacon_clock],
./batch_validation
from libp2p/protocols/pubsub/pubsub import ValidationResult
export results, ValidationResult
logScope:
topics = "gossip_checks"
declareCounter beacon_attestations_dropped_queue_full,
"Number of attestations dropped because queue is full"
declareCounter beacon_aggregates_dropped_queue_full,
"Number of aggregates dropped because queue is full"
declareCounter beacon_sync_messages_dropped_queue_full,
"Number of sync committee messages dropped because queue is full"
declareCounter beacon_contributions_dropped_queue_full,
"Number of sync committee contributions dropped because queue is full"
# This result is a little messy in that it returns Result.ok for
# ValidationResult.Accept and an err for the others - this helps transport
# an error message to callers but could arguably be done in an cleaner way.
type
ValidationError* = (ValidationResult, cstring)
template errIgnore*(msg: cstring): untyped =
err((ValidationResult.Ignore, cstring msg))
template errReject*(msg: cstring): untyped =
err((ValidationResult.Reject, cstring msg))
# Internal checks
# ----------------------------------------------------------------
func check_attestation_block(
pool: AttestationPool, attestationSlot: Slot, blck: BlockRef):
Result[void, ValidationError] =
# The voted-for block must be a descendant of the finalized block, thus it
# must at least as new than the finalized checkpoint - in theory it could be
# equal, but then we're voting for an already-finalized block which is pretty
# useless - other blocks that are not rooted in the finalized chain will be
# pruned by the chain dag, and thus we can no longer get a BlockRef for them
if not (blck.slot > pool.dag.finalizedHead.slot):
return errIgnore("Voting for already-finalized block")
# The attestation shouldn't be voting for a block that didn't exist at the
# time - not in spec, but hard to reason about
if not (attestationSlot >= blck.slot):
return errIgnore("Voting for block that didn't exist at the time")
# We'll also cap it at 4 epochs which is somewhat arbitrary, but puts an
# upper bound on the processing done to validate the attestation
# TODO revisit with less arbitrary approach
if not ((attestationSlot - blck.slot) <= uint64(4 * SLOTS_PER_EPOCH)):
return errIgnore("Voting for very old block")
ok()
func check_propagation_slot_range(
msgSlot: Slot, wallTime: BeaconTime): Result[Slot, ValidationError] =
let
futureSlot = (wallTime + MAXIMUM_GOSSIP_CLOCK_DISPARITY).toSlot()
if not futureSlot.afterGenesis or msgSlot > futureSlot.slot:
return errIgnore("Attestation slot in the future")
let
pastSlot = (wallTime - MAXIMUM_GOSSIP_CLOCK_DISPARITY).toSlot()
# https://github.com/ethereum/consensus-specs/blob/v1.1.9/specs/phase0/p2p-interface.md#configuration
# The spec value of ATTESTATION_PROPAGATION_SLOT_RANGE is 32, but it can
# retransmit attestations on the cusp of being out of spec, and which by
# the time they reach their destination might be out of spec.
const ATTESTATION_PROPAGATION_SLOT_RANGE = 28
if pastSlot.afterGenesis and
msgSlot + ATTESTATION_PROPAGATION_SLOT_RANGE < pastSlot.slot:
return errIgnore("Attestation slot in the past")
ok(msgSlot)
func check_beacon_and_target_block(
pool: var AttestationPool, data: AttestationData):
Result[BlockSlot, ValidationError] =
# The block being voted for (data.beacon_block_root) passes validation - by
# extension, the target block must at that point also pass validation.
# The target block is returned.
# We rely on the chain DAG to have been validated, so check for the existence
# of the block in the pool.
let blck = pool.dag.getBlockRef(data.beacon_block_root).valueOr:
pool.quarantine[].addMissing(data.beacon_block_root)
return errIgnore("Attestation block unknown")
# Not in spec - check that rewinding to the state is sane
? check_attestation_block(pool, data.slot, blck)
# [REJECT] The attestation's target block is an ancestor of the block named
# in the LMD vote -- i.e. get_ancestor(store,
# attestation.data.beacon_block_root,
# compute_start_slot_at_epoch(attestation.data.target.epoch)) ==
# attestation.data.target.root
# the sanity of target.epoch has been checked by check_attestation_slot_target
let
target = blck.atSlot(data.target.epoch.start_slot())
if isNil(target.blck):
# Shouldn't happen - we've checked that the target epoch is within range
# already
return errReject("Attestation target block not found")
if not (target.blck.root == data.target.root):
return errReject(
"Attestation target block not the correct ancestor of LMD vote block")
ok(target)
func check_aggregation_count(
attestation: Attestation, singular: bool): Result[void, ValidationError] =
let ones = attestation.aggregation_bits.countOnes()
if singular and ones != 1:
return errReject("Attestation must have a single attestation bit set")
elif not singular and ones < 1:
return errReject("Attestation must have at least one attestation bit set")
ok()
func check_attestation_subnet(
epochRef: EpochRef, slot: Slot, committee_index: CommitteeIndex,
subnet_id: SubnetId): Result[void, ValidationError] =
let
expectedSubnet = compute_subnet_for_attestation(
get_committee_count_per_slot(epochRef), slot, committee_index)
if expectedSubnet != subnet_id:
return errReject("Attestation not on the correct subnet")
ok()
# Gossip Validation
# ----------------------------------------------------------------
template checkedReject(msg: cstring): untyped =
if verifyFinalization in pool.dag.updateFlags:
# This doesn't depend on the wall clock or the exact state of the DAG; it's
# an internal consistency/correctness check only, and effectively never has
# false positives. These don't, for example, arise from timeouts.
raiseAssert $msg
errReject(msg)
template checkedReject(error: ValidationError): untyped =
doAssert error[0] == ValidationResult.Reject
if verifyFinalization in pool.dag.updateFlags:
# This doesn't depend on the wall clock or the exact state of the DAG; it's
# an internal consistency/correctness check only, and effectively never has
# false positives. These don't, for example, arise from timeouts.
raiseAssert $error[1]
err(error)
template validateBeaconBlockBellatrix(
signed_beacon_block: phase0.SignedBeaconBlock |
altair.SignedBeaconBlock,
parent: BlockRef): untyped =
discard
# https://github.com/ethereum/consensus-specs/blob/v1.1.7/specs/merge/p2p-interface.md#beacon_block
template validateBeaconBlockBellatrix(
signed_beacon_block: bellatrix.SignedBeaconBlock,
parent: BlockRef): untyped =
# If the execution is enabled for the block -- i.e.
# is_execution_enabled(state, block.body) then validate the following:
let executionEnabled =
if signed_beacon_block.message.body.execution_payload !=
default(ExecutionPayload):
true
elif dag.getEpochRef(parent, parent.slot.epoch, true).expect(
"parent EpochRef doesn't fail").merge_transition_complete:
# Should usually be inexpensive, but could require cache refilling - the
# parent block can be no older than the latest finalized block
true
else:
# Somewhat more expensive fallback, with database I/O, but should be
# mostly relevant around merge transition epochs. It's possible that
# the previous block is phase 0 or Altair, if this is the transition
# block itself.
let blockData = dag.getForkedBlock(parent)
case blockData.kind:
of BeaconBlockFork.Phase0:
false
of BeaconBlockFork.Altair:
false
of BeaconBlockFork.Bellatrix:
# https://github.com/ethereum/consensus-specs/blob/v1.1.10/specs/bellatrix/beacon-chain.md#process_execution_payload
# shows how this gets folded into the state each block; checking this
# is equivalent, without ever requiring state replay or any similarly
# expensive computation.
blockData.bellatrixData.message.body.execution_payload !=
default(ExecutionPayload)
if executionEnabled:
# [REJECT] The block's execution payload timestamp is correct with respect
# to the slot -- i.e. execution_payload.timestamp ==
# compute_timestamp_at_slot(state, block.slot).
let timestampAtSlot =
withState(dag.headState.data):
compute_timestamp_at_slot(state.data, signed_beacon_block.message.slot)
if not (signed_beacon_block.message.body.execution_payload.timestamp ==
timestampAtSlot):
quarantine[].addUnviable(signed_beacon_block.root)
return errReject("BeaconBlock: Mismatched execution payload timestamp")
# https://github.com/ethereum/consensus-specs/blob/v1.1.9/specs/phase0/p2p-interface.md#beacon_block
# https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/bellatrix/p2p-interface.md#beacon_block
proc validateBeaconBlock*(
dag: ChainDAGRef, quarantine: ref Quarantine,
signed_beacon_block: phase0.SignedBeaconBlock | altair.SignedBeaconBlock |
bellatrix.SignedBeaconBlock,
wallTime: BeaconTime, flags: UpdateFlags): Result[void, ValidationError] =
# In general, checks are ordered from cheap to expensive. Especially, crypto
# verification could be quite a bit more expensive than the rest. This is an
# externally easy-to-invoke function by tossing network packets at the node.
# [IGNORE] The block is not from a future slot (with a
# MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance) -- i.e. validate that
# signed_beacon_block.message.slot <= current_slot (a client MAY queue future
# blocks for processing at the appropriate slot).
if not (signed_beacon_block.message.slot <=
(wallTime + MAXIMUM_GOSSIP_CLOCK_DISPARITY).slotOrZero):
return errIgnore("BeaconBlock: slot too high")
# [IGNORE] The block is from a slot greater than the latest finalized slot --
# i.e. validate that signed_beacon_block.message.slot >
# compute_start_slot_at_epoch(state.finalized_checkpoint.epoch)
if not (signed_beacon_block.message.slot > dag.finalizedHead.slot):
return errIgnore("BeaconBlock: slot already finalized")
# [IGNORE] The block is the first block with valid signature received for the
# proposer for the slot, signed_beacon_block.message.slot.
#
# While this condition is similar to the proposer slashing condition at
# https://github.com/ethereum/consensus-specs/blob/v1.1.10/specs/phase0/validator.md#proposer-slashing
# it's not identical, and this check does not address slashing:
#
# (1) The beacon blocks must be conflicting, i.e. different, for the same
# slot and proposer. This check also catches identical blocks.
#
# (2) By this point in the function, it's not been checked whether they're
# signed yet. As in general, expensive checks should be deferred, this
# would add complexity not directly relevant this function.
#
# (3) As evidenced by point (1), the similarity in the validation condition
# and slashing condition, while not coincidental, aren't similar enough
# to combine, as one or the other might drift.
#
# (4) Furthermore, this function, as much as possible, simply returns a yes
# or no answer, without modifying other state for p2p network interface
# validation. Complicating this interface, for the sake of sharing only
# couple lines of code, wouldn't be worthwhile.
#
# TODO might check unresolved/orphaned blocks too, and this might not see all
# blocks at a given slot (though, in theory, those get checked elsewhere), or
# adding metrics that count how often these conditions occur.
if dag.containsForkBlock(signed_beacon_block.root):
# The gossip algorithm itself already does one round of hashing to find
# already-seen data, but it is fairly aggressive about forgetting about
# what it has seen already
# "[IGNORE] The block is the first block ..."
return errIgnore("BeaconBlock: already seen")
let
slotBlock = getBlockAtSlot(dag, signed_beacon_block.message.slot)
if slotBlock.isProposed() and
slotBlock.blck.slot == signed_beacon_block.message.slot:
let data = dag.getForkedBlock(slotBlock.blck)
if getForkedBlockField(data, proposer_index) ==
signed_beacon_block.message.proposer_index and
data.signature.toRaw() != signed_beacon_block.signature.toRaw():
return errIgnore("BeaconBlock: already proposed in the same slot")
# [IGNORE] The block's parent (defined by block.parent_root) has been seen
# (via both gossip and non-gossip sources) (a client MAY queue blocks for
# processing once the parent block is retrieved).
#
# And implicitly:
# [REJECT] The block's parent (defined by block.parent_root) passes validation.
let parent = dag.getBlockRef(signed_beacon_block.message.parent_root).valueOr:
if signed_beacon_block.message.parent_root in quarantine[].unviable:
quarantine[].addUnviable(signed_beacon_block.root)
return errReject("BeaconBlock: parent from unviable fork")
# When the parent is missing, we can't validate the block - we'll queue it
# in the quarantine for later processing
if not quarantine[].addOrphan(
dag.finalizedHead.slot,
ForkedSignedBeaconBlock.init(signed_beacon_block)):
debug "Block quarantine full"
return errIgnore("BeaconBlock: Parent not found")
# [REJECT] The block is from a higher slot than its parent.
if not (signed_beacon_block.message.slot > parent.bid.slot):
return errReject("BeaconBlock: block not from higher slot than its parent")
# [REJECT] The current finalized_checkpoint is an ancestor of block -- i.e.
# get_ancestor(store, block.parent_root,
# compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)) ==
# store.finalized_checkpoint.root
let
finalized_checkpoint = getStateField(
dag.headState.data, finalized_checkpoint)
ancestor = get_ancestor(parent, finalized_checkpoint.epoch.start_slot)
if ancestor.isNil:
# This shouldn't happen: we should always be able to trace the parent back
# to the finalized checkpoint (else it wouldn't be in the DAG)
return errIgnore("BeaconBlock: Can't find ancestor")
if not (
finalized_checkpoint.root == ancestor.root or
finalized_checkpoint.root.isZero):
quarantine[].addUnviable(signed_beacon_block.root)
return errReject("BeaconBlock: Finalized checkpoint not an ancestor")
# [REJECT] The block is proposed by the expected proposer_index for the
# block's slot in the context of the current shuffling (defined by
# parent_root/slot). If the proposer_index cannot immediately be verified
# against the expected shuffling, the block MAY be queued for later
# processing while proposers for the block's branch are calculated -- in such
# a case do not REJECT, instead IGNORE this message.
let
proposer = getProposer(dag, parent, signed_beacon_block.message.slot)
if proposer.isNone:
warn "cannot compute proposer for message"
return errIgnore("BeaconBlock: Cannot compute proposer") # internal issue
if uint64(proposer.get()) != signed_beacon_block.message.proposer_index:
quarantine[].addUnviable(signed_beacon_block.root)
return errReject("BeaconBlock: Unexpected proposer proposer")
# [REJECT] The proposer signature, signed_beacon_block.signature, is valid
# with respect to the proposer_index pubkey.
if not verify_block_signature(
dag.forkAtEpoch(signed_beacon_block.message.slot.epoch),
getStateField(dag.headState.data, genesis_validators_root),
signed_beacon_block.message.slot,
signed_beacon_block.root,
dag.validatorKey(proposer.get()).get(),
signed_beacon_block.signature):
quarantine[].addUnviable(signed_beacon_block.root)
return errReject("BeaconBlock: Invalid proposer signature")
validateBeaconBlockBellatrix(signed_beacon_block, parent)
ok()
# https://github.com/ethereum/consensus-specs/blob/v1.1.9/specs/phase0/p2p-interface.md#beacon_attestation_subnet_id
proc validateAttestation*(
pool: ref AttestationPool,
batchCrypto: ref BatchCrypto,
attestation: Attestation,
wallTime: BeaconTime,
subnet_id: SubnetId, checkSignature: bool):
Future[Result[
tuple[attesting_index: ValidatorIndex, sig: CookedSig],
ValidationError]] {.async.} =
# Some of the checks below have been reordered compared to the spec, to
# perform the cheap checks first - in particular, we want to avoid loading
# an `EpochRef` and checking signatures. This reordering might lead to
# different IGNORE/REJECT results in turn affecting gossip scores.
# [REJECT] The attestation's epoch matches its target -- i.e.
# attestation.data.target.epoch ==
# compute_epoch_at_slot(attestation.data.slot)
let slot = block:
let v = check_attestation_slot_target(attestation.data)
if v.isErr():
return errReject(v.error())
v.get()
# attestation.data.slot is within the last ATTESTATION_PROPAGATION_SLOT_RANGE
# slots (within a MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance) -- i.e.
# attestation.data.slot + ATTESTATION_PROPAGATION_SLOT_RANGE >= current_slot
# >= attestation.data.slot (a client MAY queue future attestations for
# processing at the appropriate slot).
block:
let v = check_propagation_slot_range(slot, wallTime) # [IGNORE]
if v.isErr():
return err(v.error())
# The attestation is unaggregated -- that is, it has exactly one
# participating validator (len([bit for bit in attestation.aggregation_bits
# if bit == 0b1]) == 1).
block:
let v = check_aggregation_count(attestation, singular = true) # [REJECT]
if v.isErr():
return checkedReject(v.error)
# The block being voted for (attestation.data.beacon_block_root) has been seen
# (via both gossip and non-gossip sources) (a client MAY queue attestations for
# processing once block is retrieved).
# The block being voted for (attestation.data.beacon_block_root) passes
# validation.
# [IGNORE] if block is unseen so far and enqueue it in missing blocks
let target = block:
let v = check_beacon_and_target_block(pool[], attestation.data) # [IGNORE/REJECT]
if v.isErr():
return err(v.error)
v.get()
# The following rule follows implicitly from that we clear out any
# unviable blocks from the chain dag:
#
# The current finalized_checkpoint is an ancestor of the block defined by
# attestation.data.beacon_block_root -- i.e. get_ancestor(store,
# attestation.data.beacon_block_root,
# compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)) ==
# store.finalized_checkpoint.root
let
epochRef = block:
let tmp = pool.dag.getEpochRef(target.blck, target.slot.epoch, false)
if isErr(tmp): # shouldn't happen since we verified target
warn "No EpochRef for attestation",
attestation = shortLog(attestation), target = shortLog(target)
return errIgnore("Attestation: no EpochRef")
tmp.get()
# [REJECT] The committee index is within the expected range -- i.e.
# data.index < get_committee_count_per_slot(state, data.target.epoch).
let committee_index = block:
let idx = epochRef.get_committee_index(attestation.data.index)
if idx.isErr():
return checkedReject("Attestation: committee index not within expected range")
idx.get()
# [REJECT] The attestation is for the correct subnet -- i.e.
# compute_subnet_for_attestation(committees_per_slot,
# attestation.data.slot, attestation.data.index) == subnet_id, where
# committees_per_slot = get_committee_count_per_slot(state,
# attestation.data.target.epoch), which may be pre-computed along with the
# committee information for the signature check.
block:
let v = check_attestation_subnet(
epochRef, attestation.data.slot, committee_index, subnet_id) # [REJECT]
if v.isErr():
return err(v.error)
# [REJECT] The number of aggregation bits matches the committee size -- i.e.
# len(attestation.aggregation_bits) == len(get_beacon_committee(state,
# data.slot, data.index)).
#
# This uses the same epochRef as data.target.epoch, because the attestation's
# epoch matches its target and attestation.data.target.root is an ancestor of
# attestation.data.beacon_block_root.
if not (attestation.aggregation_bits.lenu64 == get_beacon_committee_len(
epochRef, attestation.data.slot, committee_index)):
return checkedReject(
"Attestation: number of aggregation bits and committee size mismatch")
let
fork = pool.dag.forkAtEpoch(attestation.data.slot.epoch)
genesis_validators_root =
getStateField(pool.dag.headState.data, genesis_validators_root)
attesting_index = get_attesting_indices_one(
epochRef, slot, committee_index, attestation.aggregation_bits)
# The number of aggregation bits matches the committee size, which ensures
# this condition holds.
doAssert attesting_index.isSome(), "We've checked bits length and one count already"
let validator_index = attesting_index.get()
# There has been no other valid attestation seen on an attestation subnet
# that has an identical `attestation.data.target.epoch` and participating
# validator index.
# Slightly modified to allow only newer attestations than were previously
# seen (no point in propagating older votes)
if (pool.nextAttestationEpoch.lenu64 > validator_index.uint64) and
pool.nextAttestationEpoch[validator_index].subnet >
attestation.data.target.epoch:
return errIgnore("Attestation: Validator has already voted in epoch")
let pubkey = epochRef.validatorKey(validator_index)
if pubkey.isNone():
# can't happen, in theory, because we checked the aggregator index above
return errIgnore("Attestation: cannot find validator pubkey")
# In the spec, is_valid_indexed_attestation is used to verify the signature -
# here, we do a batch verification instead
let sig =
if checkSignature:
# Attestation signatures are batch-verified
let deferredCrypto = batchCrypto
.scheduleAttestationCheck(
fork, genesis_validators_root, attestation.data,
pubkey.get(), attestation.signature)
if deferredCrypto.isErr():
return checkedReject(deferredCrypto.error)
let (cryptoFut, sig) = deferredCrypto.get()
# Await the crypto check
var x = (await cryptoFut)
case x
of BatchResult.Invalid:
return checkedReject("Attestation: invalid signature")
of BatchResult.Timeout:
beacon_attestations_dropped_queue_full.inc()
return errIgnore("Attestation: timeout checking signature")
of BatchResult.Valid:
sig # keep going only in this case
else:
let sig = attestation.signature.load()
if not sig.isSome():
return checkedReject("Attestation: unable to load signature")
sig.get()
# Only valid attestations go in the list, which keeps validator_index
# in range
if not (pool.nextAttestationEpoch.lenu64 > validator_index.uint64):
pool.nextAttestationEpoch.setLen(validator_index.int + 1)
pool.nextAttestationEpoch[validator_index].subnet =
attestation.data.target.epoch + 1
return ok((validator_index, sig))
# https://github.com/ethereum/consensus-specs/blob/v1.1.9/specs/phase0/p2p-interface.md#beacon_aggregate_and_proof
proc validateAggregate*(
pool: ref AttestationPool,
batchCrypto: ref BatchCrypto,
signedAggregateAndProof: SignedAggregateAndProof,
wallTime: BeaconTime):
Future[Result[
tuple[attestingIndices: seq[ValidatorIndex], sig: CookedSig],
ValidationError]] {.async.} =
# Some of the checks below have been reordered compared to the spec, to
# perform the cheap checks first - in particular, we want to avoid loading
# an `EpochRef` and checking signatures. This reordering might lead to
# different IGNORE/REJECT results in turn affecting gossip scores.
template aggregate_and_proof: untyped = signedAggregateAndProof.message
template aggregate: untyped = aggregate_and_proof.aggregate
# [REJECT] The aggregate attestation's epoch matches its target -- i.e.
# `aggregate.data.target.epoch == compute_epoch_at_slot(aggregate.data.slot)`
let slot = block:
let v = check_attestation_slot_target(aggregate.data)
if v.isErr():
return checkedReject(v.error)
v.get()
# [IGNORE] aggregate.data.slot is within the last
# ATTESTATION_PROPAGATION_SLOT_RANGE slots (with a
# MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance) -- i.e. aggregate.data.slot +
# ATTESTATION_PROPAGATION_SLOT_RANGE >= current_slot >= aggregate.data.slot
block:
let v = check_propagation_slot_range(slot, wallTime) # [IGNORE]
if v.isErr():
return err(v.error())
# [IGNORE] The aggregate is the first valid aggregate received for the
# aggregator with index aggregate_and_proof.aggregator_index for the epoch
# aggregate.data.target.epoch.
# Slightly modified to allow only newer attestations than were previously
# seen (no point in propagating older votes)
if (pool.nextAttestationEpoch.lenu64 >
aggregate_and_proof.aggregator_index) and
pool.nextAttestationEpoch[
aggregate_and_proof.aggregator_index].aggregate >
aggregate.data.target.epoch:
return errIgnore("Aggregate: validator has already aggregated in epoch")
# [REJECT] The attestation has participants -- that is,
# len(get_attesting_indices(state, aggregate.data, aggregate.aggregation_bits)) >= 1.
#
# get_attesting_indices() is:
# committee = get_beacon_committee(state, data.slot, data.index)
# return set(index for i, index in enumerate(committee) if bits[i])
#
# the attestation doesn't have participants is iff either:
# (1) the aggregation bits are all 0; or
# (2) the non-zero aggregation bits don't overlap with extant committee
# members, i.e. they counts don't match.
# But (2) would reflect an invalid aggregation in other ways, so reject it
# either way.
block:
let v = check_aggregation_count(aggregate, singular = false) # [REJECT]
if v.isErr():
return err(v.error)
# [REJECT] The block being voted for (aggregate.data.beacon_block_root)
# passes validation.
# [IGNORE] if block is unseen so far and enqueue it in missing blocks
let target = block:
let v = check_beacon_and_target_block(pool[], aggregate.data) # [IGNORE/REJECT]
if v.isErr():
return err(v.error)
v.get()
if pool[].covers(aggregate.data, aggregate.aggregation_bits):
# https://github.com/ethereum/consensus-specs/issues/2183 - althoughh this
# check was temporarily removed from the spec, the intent is to reinstate it
# per discussion in the ticket.
#
# [IGNORE] The valid aggregate attestation defined by
# `hash_tree_root(aggregate)` has _not_ already been seen
# (via aggregate gossip, within a verified block, or through the creation of
# an equivalent aggregate locally).
# Our implementation of this check is slightly different in that it doesn't
# consider aggregates from verified blocks - this would take a rather heavy
# index to work correcly under fork conditions - we also check for coverage
# of attestation bits instead of comparing with full root of aggreagte:
# this captures the spirit of the checkk by ignoring aggregates that are
# strict subsets of other, already-seen aggregates.
return errIgnore("Aggregate already covered")
let
epochRef = block:
let tmp = pool.dag.getEpochRef(target.blck, target.slot.epoch, false)
if tmp.isErr: # shouldn't happen since we verified target
warn "No EpochRef for attestation - report bug",
aggregate = shortLog(aggregate), target = shortLog(target)
return errIgnore("Aggregate: no EpochRef")
tmp.get()
# [REJECT] The committee index is within the expected range -- i.e.
# data.index < get_committee_count_per_slot(state, data.target.epoch).
let committee_index = block:
let idx = epochRef.get_committee_index(aggregate.data.index)
if idx.isErr():
return checkedReject("Attestation: committee index not within expected range")
idx.get()
# [REJECT] aggregate_and_proof.selection_proof selects the validator as an
# aggregator for the slot -- i.e. is_aggregator(state, aggregate.data.slot,
# aggregate.data.index, aggregate_and_proof.selection_proof) returns True.
if not is_aggregator(
epochRef, slot, committee_index, aggregate_and_proof.selection_proof):
return checkedReject("Aggregate: incorrect aggregator")
# [REJECT] The aggregator's validator index is within the committee -- i.e.
# aggregate_and_proof.aggregator_index in get_beacon_committee(state,
# aggregate.data.slot, aggregate.data.index).
if aggregate_and_proof.aggregator_index.ValidatorIndex notin
get_beacon_committee(epochRef, slot, committee_index):
return checkedReject("Aggregate: aggregator's validator index not in committee")
# 1. [REJECT] The aggregate_and_proof.selection_proof is a valid signature of the
# aggregate.data.slot by the validator with index
# aggregate_and_proof.aggregator_index.
# get_slot_signature(state, aggregate.data.slot, privkey)
# 2. [REJECT] The aggregator signature, signed_aggregate_and_proof.signature, is valid.
# 3. [REJECT] The signature of aggregate is valid.
let
fork = pool.dag.forkAtEpoch(aggregate.data.slot.epoch)
genesis_validators_root =
getStateField(pool.dag.headState.data, genesis_validators_root)
attesting_indices = get_attesting_indices(
epochRef, slot, committee_index, aggregate.aggregation_bits)
let deferredCrypto = batchCrypto
.scheduleAggregateChecks(
fork, genesis_validators_root,
signed_aggregate_and_proof, epochRef, attesting_indices
)
if deferredCrypto.isErr():
return checkedReject(deferredCrypto.error)
let
(aggregatorFut, slotFut, aggregateFut, sig) = deferredCrypto.get()
block:
# [REJECT] The aggregator signature, signed_aggregate_and_proof.signature, is valid.
var x = await aggregatorFut
case x
of BatchResult.Invalid:
return checkedReject("Aggregate: invalid aggregator signature")
of BatchResult.Timeout:
beacon_aggregates_dropped_queue_full.inc()
return errIgnore("Aggregate: timeout checking aggregator signature")
of BatchResult.Valid:
discard
block:
# [REJECT] aggregate_and_proof.selection_proof
var x = await slotFut
case x
of BatchResult.Invalid:
return checkedReject("Aggregate: invalid slot signature")
of BatchResult.Timeout:
beacon_aggregates_dropped_queue_full.inc()
return errIgnore("Aggregate: timeout checking slot signature")
of BatchResult.Valid:
discard
block:
# [REJECT] The aggregator signature, signed_aggregate_and_proof.signature, is valid.
var x = await aggregateFut
case x
of BatchResult.Invalid:
return checkedReject("Aggregate: invalid aggregate signature")
of BatchResult.Timeout:
beacon_aggregates_dropped_queue_full.inc()
return errIgnore("Aggregate: timeout checking aggregate signature")
of BatchResult.Valid:
discard
# The following rule follows implicitly from that we clear out any
# unviable blocks from the chain dag:
#
# The current finalized_checkpoint is an ancestor of the block defined by
# aggregate.data.beacon_block_root -- i.e. get_ancestor(store,
# aggregate.data.beacon_block_root,
# compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)) ==
# store.finalized_checkpoint.root
# Only valid aggregates go in the list
if pool.nextAttestationEpoch.lenu64 <= aggregate_and_proof.aggregator_index:
pool.nextAttestationEpoch.setLen(
aggregate_and_proof.aggregator_index.int + 1)
pool.nextAttestationEpoch[aggregate_and_proof.aggregator_index].aggregate =
aggregate.data.target.epoch + 1
return ok((attesting_indices, sig))
# https://github.com/ethereum/consensus-specs/blob/v1.1.9/specs/phase0/p2p-interface.md#attester_slashing
proc validateAttesterSlashing*(
pool: ExitPool, attester_slashing: AttesterSlashing):
Result[void, ValidationError] =
# [IGNORE] At least one index in the intersection of the attesting indices of
# each attestation has not yet been seen in any prior attester_slashing (i.e.
# attester_slashed_indices = set(attestation_1.attesting_indices).intersection(attestation_2.attesting_indices),
# verify if any(attester_slashed_indices.difference(prior_seen_attester_slashed_indices))).
# TODO sequtils2 should be able to make this more reasonable, from asSeq on
# down, and can sort and just find intersection that way
if pool.isSeen(attester_slashing):
return errIgnore(
"AttesterSlashing: attester-slashed index already attester-slashed")
# [REJECT] All of the conditions within process_attester_slashing pass
# validation.
let attester_slashing_validity =
check_attester_slashing(pool.dag.headState.data, attester_slashing, {})
if attester_slashing_validity.isErr:
return err((ValidationResult.Reject, attester_slashing_validity.error))
ok()
# https://github.com/ethereum/consensus-specs/blob/v1.1.9/specs/phase0/p2p-interface.md#proposer_slashing
proc validateProposerSlashing*(
pool: ExitPool, proposer_slashing: ProposerSlashing):
Result[void, ValidationError] =
# Not from spec; the rest of NBC wouldn't have correctly processed it either.
if proposer_slashing.signed_header_1.message.proposer_index > high(int).uint64:
return errIgnore("ProposerSlashing: proposer-slashed index too high")
# [IGNORE] The proposer slashing is the first valid proposer slashing
# received for the proposer with index
# proposer_slashing.signed_header_1.message.proposer_index.
if pool.isSeen(proposer_slashing):
return errIgnore(
"ProposerSlashing: proposer-slashed index already proposer-slashed")
# [REJECT] All of the conditions within process_proposer_slashing pass validation.
let proposer_slashing_validity =
check_proposer_slashing(pool.dag.headState.data, proposer_slashing, {})
if proposer_slashing_validity.isErr:
return err((ValidationResult.Reject, proposer_slashing_validity.error))
ok()
# https://github.com/ethereum/consensus-specs/blob/v1.1.9/specs/phase0/p2p-interface.md#voluntary_exit
proc validateVoluntaryExit*(
pool: ExitPool, signed_voluntary_exit: SignedVoluntaryExit):
Result[void, ValidationError] =
# [IGNORE] The voluntary exit is the first valid voluntary exit received for
# the validator with index signed_voluntary_exit.message.validator_index.
if signed_voluntary_exit.message.validator_index >=
getStateField(pool.dag.headState.data, validators).lenu64:
return errIgnore("VoluntaryExit: validator index too high")
# Given that getStateField(pool.dag.headState, validators) is a seq,
# signed_voluntary_exit.message.validator_index.int is already valid, but
# check explicitly if one changes that data structure.
if pool.isSeen(signed_voluntary_exit):
return errIgnore("VoluntaryExit: validator index already voluntarily exited")
# [REJECT] All of the conditions within process_voluntary_exit pass
# validation.
let voluntary_exit_validity =
check_voluntary_exit(
pool.dag.cfg, pool.dag.headState.data, signed_voluntary_exit, {})
if voluntary_exit_validity.isErr:
return err((ValidationResult.Reject, voluntary_exit_validity.error))
# Send notification about new voluntary exit via callback
if not(isNil(pool.onVoluntaryExitReceived)):
pool.onVoluntaryExitReceived(signed_voluntary_exit)
ok()
# https://github.com/ethereum/consensus-specs/blob/v1.1.10/specs/altair/p2p-interface.md#sync_committee_subnet_id
proc validateSyncCommitteeMessage*(
dag: ChainDAGRef,
batchCrypto: ref BatchCrypto,
syncCommitteeMsgPool: ref SyncCommitteeMsgPool,
msg: SyncCommitteeMessage,
subcommitteeIdx: SyncSubcommitteeIndex,
wallTime: BeaconTime,
checkSignature: bool):
Future[Result[(seq[uint64], CookedSig), ValidationError]] {.async.} =
block:
# [IGNORE] The message's slot is for the current slot (with a
# `MAXIMUM_GOSSIP_CLOCK_DISPARITY` allowance), i.e.
# `sync_committee_message.slot == current_slot`.
let v = check_propagation_slot_range(msg.slot, wallTime)
if v.isErr():
return err(v.error())
# [REJECT] The subnet_id is valid for the given validator
# i.e. subnet_id in compute_subnets_for_sync_committee(state, sync_committee_message.validator_index).
# Note this validation implies the validator is part of the broader
# current sync committee along with the correct subcommittee.
# This check also ensures that the validator index is in range
let positionsInSubcommittee = dag.getSubcommitteePositions(
msg.slot + 1, subcommitteeIdx, msg.validator_index)
if positionsInSubcommittee.len == 0:
return errReject(
"SyncCommitteeMessage: originator not part of sync committee")
block:
# [IGNORE] There has been no other valid sync committee message for the
# declared `slot` for the validator referenced by
# `sync_committee_message.validator_index`
#
# Note this validation is per topic so that for a given slot, multiple
# messages could be forwarded with the same validator_index as long as
# the subnet_ids are distinct.
if syncCommitteeMsgPool[].isSeen(msg, subcommitteeIdx):
return errIgnore("SyncCommitteeMessage: duplicate message")
# [REJECT] The signature is valid for the message beacon_block_root for the
# validator referenced by validator_index.
let
epoch = msg.slot.epoch
fork = dag.forkAtEpoch(epoch)
genesisValidatorsRoot = dag.genesisValidatorsRoot
senderPubKey = dag.validatorKey(msg.validator_index)
if senderPubKey.isNone():
return errReject("SyncCommitteeMessage: invalid validator index")
let sig =
if checkSignature:
# Attestation signatures are batch-verified
let deferredCrypto = batchCrypto
.scheduleSyncCommitteeMessageCheck(
fork, genesis_validators_root,
msg.slot, msg.beacon_block_root,
senderPubKey.get(), msg.signature)
if deferredCrypto.isErr():
return errReject(deferredCrypto.error)
# Await the crypto check
let
(cryptoFut, sig) = deferredCrypto.get()
var x = (await cryptoFut)
case x
of BatchResult.Invalid:
return errReject("SyncCommitteeMessage: invalid signature")
of BatchResult.Timeout:
beacon_sync_messages_dropped_queue_full.inc()
return errIgnore("SyncCommitteeMessage: timeout checking signature")
of BatchResult.Valid:
sig # keep going only in this case
else:
let sig = msg.signature.load()
if not sig.isSome():
return errReject("SyncCommitteeMessage: unable to load signature")
sig.get()
return ok((positionsInSubcommittee, sig))
# https://github.com/ethereum/consensus-specs/blob/v1.1.10/specs/altair/p2p-interface.md#sync_committee_contribution_and_proof
proc validateContribution*(
dag: ChainDAGRef,
batchCrypto: ref BatchCrypto,
syncCommitteeMsgPool: ref SyncCommitteeMsgPool,
msg: SignedContributionAndProof,
wallTime: BeaconTime,
checkSignature: bool):
Future[Result[(CookedSig, seq[ValidatorIndex]), ValidationError]] {.async.} =
let
syncCommitteeSlot = msg.message.contribution.slot
# [IGNORE] The contribution's slot is for the current slot
# (with a MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance)
# i.e. contribution.slot == current_slot.
block:
let v = check_propagation_slot_range(syncCommitteeSlot, wallTime) # [IGNORE]
if v.isErr():
return err(v.error())
# [REJECT] The subcommittee index is in the allowed range
# i.e. contribution.subcommittee_index < SYNC_COMMITTEE_SUBNET_COUNT.
let subcommitteeIdx = block:
let v = SyncSubcommitteeIndex.init(msg.message.contribution.subcommittee_index)
if v.isErr():
return errReject("SignedContributionAndProof: subcommittee index too high")
v.get()
# [REJECT] contribution_and_proof.selection_proof selects the validator as an aggregator for the slot
# i.e. is_sync_committee_aggregator(contribution_and_proof.selection_proof) returns True.
if not is_sync_committee_aggregator(msg.message.selection_proof):
return errReject("SignedContributionAndProof: invalid selection_proof")
# [IGNORE] The sync committee contribution is the first valid contribution
# received for the aggregator with index contribution_and_proof.aggregator_index
# for the slot contribution.slot and subcommittee index contribution.subcommittee_index
# (this requires maintaining a cache of size SYNC_COMMITTEE_SIZE for this
# topic that can be flushed after each slot).
if syncCommitteeMsgPool[].isSeen(msg.message):
return errIgnore("SignedContributionAndProof: duplicate contribution")
# [REJECT] The aggregator's validator index is in the declared subcommittee
# of the current sync committee.
# i.e. state.validators[contribution_and_proof.aggregator_index].pubkey in
# get_sync_subcommittee_pubkeys(state, contribution.subcommittee_index).
let
epoch = msg.message.contribution.slot.epoch
fork = dag.forkAtEpoch(epoch)
genesis_validators_root = dag.genesisValidatorsRoot
if msg.message.contribution.aggregation_bits.countOnes() == 0:
# [REJECT] The contribution has participants
# that is, any(contribution.aggregation_bits).
return errReject("SignedContributionAndProof: aggregation bits empty")
# TODO we take a copy of the participants to avoid the data going stale
# between validation and use - nonetheless, a design that avoids it and
# stays safe would be nice
let participants = dag.syncCommitteeParticipants(
msg.message.contribution.slot, subcommitteeIdx)
let sig = if checkSignature:
let deferredCrypto = batchCrypto.scheduleContributionChecks(
fork, genesis_validators_root, msg, subcommitteeIdx, dag)
if deferredCrypto.isErr():
return errReject(deferredCrypto.error)
let
(aggregatorFut, proofFut, contributionFut, sig) = deferredCrypto.get()
block:
# [REJECT] The aggregator signature, signed_contribution_and_proof.signature, is valid
var x = await aggregatorFut
case x
of BatchResult.Invalid:
return errReject("SignedContributionAndProof: invalid aggregator signature")
of BatchResult.Timeout:
beacon_contributions_dropped_queue_full.inc()
return errIgnore("SignedContributionAndProof: timeout checking aggregator signature")
of BatchResult.Valid:
discard
block:
var x = await proofFut
case x
of BatchResult.Invalid:
return errReject("SignedContributionAndProof: invalid proof")
of BatchResult.Timeout:
beacon_contributions_dropped_queue_full.inc()
return errIgnore("SignedContributionAndProof: timeout checking proof")
of BatchResult.Valid:
discard
block:
# [REJECT] The aggregator signature, signed_aggregate_and_proof.signature, is valid.
var x = await contributionFut
case x
of BatchResult.Invalid:
return errReject("SignedContributionAndProof: invalid contribution signature")
of BatchResult.Timeout:
beacon_contributions_dropped_queue_full.inc()
return errIgnore("SignedContributionAndProof: timeout checking contribution signature")
of BatchResult.Valid:
discard
sig
else:
let sig = msg.message.contribution.signature.load()
if not sig.isSome():
return errReject("SyncCommitteeMessage: unable to load signature")
sig.get()
return ok((sig, participants))
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