368 lines
16 KiB
Nim
368 lines
16 KiB
Nim
# beacon_chain
|
|
# Copyright (c) 2019-2020 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
|
|
options, chronicles,
|
|
./spec/[
|
|
beaconstate, datatypes, crypto, digest, helpers, network, validator,
|
|
signatures],
|
|
./block_pools/[spec_cache, chain_dag, quarantine], ./attestation_pool,
|
|
./beacon_node_types, ./ssz
|
|
|
|
logScope:
|
|
topics = "att_aggr"
|
|
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.12.2/specs/phase0/validator.md#aggregation-selection
|
|
func is_aggregator(state: BeaconState, slot: Slot, index: CommitteeIndex,
|
|
slot_signature: ValidatorSig, cache: var StateCache): bool =
|
|
let
|
|
committee_len = get_beacon_committee_len(state, slot, index, cache)
|
|
modulo = max(1'u64, committee_len div TARGET_AGGREGATORS_PER_COMMITTEE)
|
|
bytes_to_uint64(eth2digest(slot_signature.toRaw()).data[0..7]) mod modulo == 0
|
|
|
|
proc aggregate_attestations*(
|
|
pool: AttestationPool, state: BeaconState, index: CommitteeIndex,
|
|
privkey: ValidatorPrivKey, trailing_distance: uint64,
|
|
cache: var StateCache): Option[AggregateAndProof] =
|
|
doAssert state.slot >= trailing_distance
|
|
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.12.2/specs/phase0/p2p-interface.md#configuration
|
|
doAssert trailing_distance <= ATTESTATION_PROPAGATION_SLOT_RANGE
|
|
|
|
let
|
|
slot = state.slot - trailing_distance
|
|
slot_signature = get_slot_signature(
|
|
state.fork, state.genesis_validators_root, slot, privkey)
|
|
|
|
doAssert slot + ATTESTATION_PROPAGATION_SLOT_RANGE >= state.slot
|
|
doAssert state.slot >= slot
|
|
|
|
doAssert index.uint64 < get_committee_count_per_slot(state, slot.epoch, cache)
|
|
|
|
# TODO for testing purposes, refactor this into the condition check
|
|
# and just calculation
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.12.2/specs/phase0/validator.md#aggregation-selection
|
|
if not is_aggregator(state, slot, index, slot_signature, cache):
|
|
return none(AggregateAndProof)
|
|
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/validator.md#attestation-data
|
|
# describes how to construct an attestation, which applies for makeAttestationData(...)
|
|
# TODO this won't actually match anything
|
|
let attestation_data = AttestationData(
|
|
slot: slot,
|
|
index: index.uint64,
|
|
beacon_block_root: get_block_root_at_slot(state, slot))
|
|
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/validator.md#construct-aggregate
|
|
# TODO once EV goes in w/ refactoring of getAttestationsForBlock, pull out the getSlot version and use
|
|
# it. This is incorrect.
|
|
for attestation in getAttestationsForBlock(pool, state):
|
|
# getAttestationsForBlock(...) already aggregates
|
|
if attestation.data == attestation_data:
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.12.2/specs/phase0/validator.md#aggregateandproof
|
|
return some(AggregateAndProof(
|
|
aggregator_index: index.uint64,
|
|
aggregate: attestation,
|
|
selection_proof: slot_signature))
|
|
|
|
none(AggregateAndProof)
|
|
|
|
proc isValidAttestationSlot(
|
|
pool: AttestationPool, attestationSlot: Slot, attestationBlck: BlockRef): bool =
|
|
# If we allow voting for very old blocks, the state transaction below will go
|
|
# nuts and keep processing empty slots
|
|
logScope:
|
|
attestationSlot
|
|
attestationBlck = shortLog(attestationBlck)
|
|
|
|
if not (attestationBlck.slot > pool.chainDag.finalizedHead.slot):
|
|
debug "voting for already-finalized block"
|
|
return false
|
|
|
|
# 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 >= attestationBlck.slot):
|
|
debug "voting for block that didn't exist at the time"
|
|
return false
|
|
|
|
if not ((attestationSlot - attestationBlck.slot) <= uint64(4 * SLOTS_PER_EPOCH)):
|
|
debug "voting for very old block"
|
|
return false
|
|
|
|
true
|
|
|
|
func checkPropagationSlotRange(data: AttestationData, current_slot: Slot): bool =
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.12.2/specs/phase0/p2p-interface.md#beacon_attestation_subnet_id
|
|
# TODO clock disparity
|
|
# attestation.data.slot + ATTESTATION_PROPAGATION_SLOT_RANGE >=
|
|
# current_slot >= attestation.data.slot
|
|
(data.slot + ATTESTATION_PROPAGATION_SLOT_RANGE >= current_slot) and
|
|
(current_slot >= data.slot)
|
|
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.12.2/specs/phase0/p2p-interface.md#beacon_attestation_subnet_id
|
|
proc isValidAttestation*(
|
|
pool: var AttestationPool, attestation: Attestation, current_slot: Slot,
|
|
topicCommitteeIndex: uint64): bool =
|
|
logScope:
|
|
topics = "att_aggr valid_att"
|
|
received_attestation = shortLog(attestation)
|
|
|
|
# TODO https://github.com/ethereum/eth2.0-specs/issues/1998
|
|
if (let v = check_attestation_slot_target(attestation.data); v.isErr):
|
|
debug "Invalid attestation", err = v.error
|
|
return false
|
|
|
|
if not checkPropagationSlotRange(attestation.data, current_slot):
|
|
debug "attestation.data.slot not within ATTESTATION_PROPAGATION_SLOT_RANGE"
|
|
return false
|
|
|
|
# The attestation is unaggregated -- that is, it has exactly one
|
|
# participating validator (len([bit for bit in attestation.aggregation_bits
|
|
# if bit == 0b1]) == 1).
|
|
# TODO a cleverer algorithm, along the lines of countOnes() in nim-stew
|
|
# But that belongs in nim-stew, since it'd break abstraction layers, to
|
|
# use details of its representation from nim-beacon-chain.
|
|
var onesCount = 0
|
|
for aggregation_bit in attestation.aggregation_bits:
|
|
if not aggregation_bit:
|
|
continue
|
|
onesCount += 1
|
|
if onesCount > 1:
|
|
debug "attestation has too many aggregation bits"
|
|
return false
|
|
if onesCount != 1:
|
|
debug "attestation has too few aggregation bits"
|
|
return false
|
|
|
|
# The attestation is the first valid attestation received for the
|
|
# participating validator for the slot, attestation.data.slot.
|
|
let maybeAttestationsSeen = getAttestationsForSlot(pool, attestation.data.slot)
|
|
if maybeAttestationsSeen.isSome:
|
|
for attestationEntry in maybeAttestationsSeen.get.attestations:
|
|
if attestation.data != attestationEntry.data:
|
|
continue
|
|
# Attestations might be aggregated eagerly or lazily; allow for both.
|
|
for validation in attestationEntry.validations:
|
|
if attestation.aggregation_bits.isSubsetOf(validation.aggregation_bits):
|
|
debug "attestation already exists at slot",
|
|
attestation_pool_validation = validation.aggregation_bits
|
|
return false
|
|
|
|
# The block being voted for (attestation.data.beacon_block_root) passes
|
|
# validation.
|
|
# We rely on the chain DAG to have been validated, so check for the existence
|
|
# of the block in the pool.
|
|
let attestationBlck = pool.chainDag.getRef(attestation.data.beacon_block_root)
|
|
if attestationBlck.isNil:
|
|
debug "Block not found"
|
|
pool.addUnresolved(attestation)
|
|
pool.quarantine.addMissing(attestation.data.beacon_block_root)
|
|
return false
|
|
|
|
if not isValidAttestationSlot(pool, attestation.data.slot, attestationBlck):
|
|
# Not in spec - check that rewinding to the state is sane
|
|
return false
|
|
|
|
let tgtBlck = pool.chainDag.getRef(attestation.data.target.root)
|
|
if tgtBlck.isNil:
|
|
debug "Target block not found"
|
|
pool.addUnresolved(attestation)
|
|
pool.quarantine.addMissing(attestation.data.beacon_block_root)
|
|
return false
|
|
|
|
# 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
|
|
ancestor = get_ancestor(
|
|
attestationBlck,
|
|
compute_start_slot_at_epoch(
|
|
pool.chainDag.headState.data.data.finalized_checkpoint.epoch))
|
|
finalized_root =
|
|
pool.chainDag.headState.data.data.finalized_checkpoint.root
|
|
if ancestor.isNil:
|
|
debug "Can't find ancestor block"
|
|
return false
|
|
# TODO spec doesn't note the pre-finalization case, but maybe necessary
|
|
if not (finalized_root in [Eth2Digest(), ancestor.root]):
|
|
debug "Incorrect ancestor block",
|
|
ancestor_root = ancestor.root,
|
|
finalized_root = pool.chainDag.headState.data.data.finalized_checkpoint.root
|
|
return false
|
|
|
|
pool.chainDag.withState(
|
|
pool.chainDag.tmpState,
|
|
tgtBlck.atSlot(attestation.data.target.epoch.compute_start_slot_at_epoch)):
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.12.2/specs/phase0/p2p-interface.md#beacon_attestation_subnet_id
|
|
# [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.
|
|
let
|
|
epochInfo = blck.getEpochInfo(state)
|
|
requiredSubnetIndex =
|
|
compute_subnet_for_attestation(
|
|
get_committee_count_per_slot(epochInfo),
|
|
attestation.data.slot, attestation.data.index.CommitteeIndex)
|
|
|
|
if requiredSubnetIndex != topicCommitteeIndex:
|
|
debug "attestation's committee index not for the correct subnet",
|
|
topicCommitteeIndex = topicCommitteeIndex,
|
|
attestation_data_index = attestation.data.index,
|
|
requiredSubnetIndex = requiredSubnetIndex
|
|
return false
|
|
|
|
# The signature of attestation is valid.
|
|
var cache = getEpochCache(blck, state)
|
|
if not is_valid_indexed_attestation(
|
|
state, get_indexed_attestation(state, attestation, cache), {}):
|
|
debug "signature verification failed"
|
|
return false
|
|
|
|
true
|
|
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/p2p-interface.md#global-topics
|
|
proc isValidAggregatedAttestation*(
|
|
pool: var AttestationPool,
|
|
signedAggregateAndProof: SignedAggregateAndProof,
|
|
current_slot: Slot): bool =
|
|
let
|
|
aggregate_and_proof = signedAggregateAndProof.message
|
|
aggregate = aggregate_and_proof.aggregate
|
|
|
|
logScope:
|
|
aggregate = shortLog(aggregate)
|
|
|
|
# TODO https://github.com/ethereum/eth2.0-specs/issues/1998
|
|
if (let v = check_attestation_slot_target(aggregate.data); v.isErr):
|
|
debug "Invalid aggregate", err = v.error
|
|
return false
|
|
|
|
# There's some overlap between this and isValidAttestation(), but unclear if
|
|
# saving a few lines of code would balance well with losing straightforward,
|
|
# spec-based synchronization.
|
|
#
|
|
# [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
|
|
if not checkPropagationSlotRange(aggregate.data, current_slot):
|
|
debug "aggregation.data.slot not within ATTESTATION_PROPAGATION_SLOT_RANGE"
|
|
return false
|
|
|
|
# [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).
|
|
#
|
|
# This is [IGNORE] and already checked by attestation pool when aggregate is
|
|
# added.
|
|
|
|
# [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.
|
|
#
|
|
# This is [IGNORE] and already effectively checked by attestation pool upon
|
|
# attempting to resolve attestations.
|
|
|
|
# [REJECT] The block being voted for (aggregate.data.beacon_block_root)
|
|
# passes validation.
|
|
let attestationBlck = pool.chainDag.getRef(aggregate.data.beacon_block_root)
|
|
if attestationBlck.isNil:
|
|
debug "Block not found"
|
|
pool.quarantine.addMissing(aggregate.data.beacon_block_root)
|
|
return false
|
|
|
|
# [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.
|
|
if isZeros(aggregate.aggregation_bits):
|
|
debug "Attestation has no or invalid aggregation bits"
|
|
return false
|
|
|
|
if not isValidAttestationSlot(pool, aggregate.data.slot, attestationBlck):
|
|
# Not in spec - check that rewinding to the state is sane
|
|
return false
|
|
|
|
# [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.
|
|
|
|
let tgtBlck = pool.chainDag.getRef(aggregate.data.target.root)
|
|
if tgtBlck.isNil:
|
|
debug "Target block not found"
|
|
pool.quarantine.addMissing(aggregate.data.beacon_block_root)
|
|
return
|
|
|
|
# TODO this could be any state in the target epoch
|
|
pool.chainDag.withState(
|
|
pool.chainDag.tmpState,
|
|
tgtBlck.atSlot(aggregate.data.target.epoch.compute_start_slot_at_epoch)):
|
|
var cache = getEpochCache(blck, state)
|
|
if not is_aggregator(
|
|
state, aggregate.data.slot, aggregate.data.index.CommitteeIndex,
|
|
aggregate_and_proof.selection_proof, cache):
|
|
debug "Incorrect aggregator"
|
|
return false
|
|
|
|
# [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(
|
|
state, aggregate.data.slot, aggregate.data.index.CommitteeIndex, cache):
|
|
debug "Aggregator's validator index not in committee"
|
|
return false
|
|
|
|
# [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)
|
|
if aggregate_and_proof.aggregator_index >= state.validators.lenu64:
|
|
debug "Invalid aggregator_index"
|
|
return false
|
|
|
|
if not verify_slot_signature(
|
|
state.fork, state.genesis_validators_root, aggregate.data.slot,
|
|
state.validators[aggregate_and_proof.aggregator_index].pubkey,
|
|
aggregate_and_proof.selection_proof):
|
|
debug "Selection_proof signature verification failed"
|
|
return false
|
|
|
|
# [REJECT] The aggregator signature, signed_aggregate_and_proof.signature, is valid.
|
|
if not verify_aggregate_and_proof_signature(
|
|
state.fork, state.genesis_validators_root, aggregate_and_proof,
|
|
state.validators[aggregate_and_proof.aggregator_index].pubkey,
|
|
signed_aggregate_and_proof.signature):
|
|
debug "Signed_aggregate_and_proof signature verification failed"
|
|
return false
|
|
|
|
# [REJECT] The signature of aggregate is valid.
|
|
if not is_valid_indexed_attestation(
|
|
state, get_indexed_attestation(state, aggregate, cache), {}):
|
|
debug "Aggregate signature verification failed"
|
|
return false
|
|
|
|
true
|