nimbus-eth2/beacon_chain/validators/attestation_aggregation.nim

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# beacon_chain
# Copyright (c) 2019-2021 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
std/options,
../spec/[datatypes, digest, crypto, helpers],
../consensus_object_pools/[spec_cache, attestation_pool]
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.1/specs/phase0/validator.md#aggregation-selection
func is_aggregator*(committee_len: uint64, slot_signature: ValidatorSig): bool =
let
modulo = max(1'u64, committee_len div TARGET_AGGREGATORS_PER_COMMITTEE)
bytes_to_uint64(eth2digest(
slot_signature.toRaw()).data.toOpenArray(0, 7)) mod modulo == 0
func is_aggregator*(epochRef: EpochRef, slot: Slot, index: CommitteeIndex,
slot_signature: ValidatorSig): bool =
let
committee_len = get_beacon_committee_len(epochRef, slot, index)
return is_aggregator(committee_len, slot_signature)
proc aggregate_attestations*(
pool: AttestationPool, epochRef: EpochRef, slot: Slot, index: CommitteeIndex,
validatorIndex: ValidatorIndex, slot_signature: ValidatorSig): Option[AggregateAndProof] =
doAssert validatorIndex in get_beacon_committee(epochRef, slot, index)
doAssert index.uint64 < get_committee_count_per_slot(epochRef)
# TODO for testing purposes, refactor this into the condition check
# and just calculation
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.1/specs/phase0/validator.md#aggregation-selection
if not is_aggregator(epochRef, slot, index, slot_signature):
return none(AggregateAndProof)
let maybe_slot_attestation = getAggregatedAttestation(pool, slot, index)
if maybe_slot_attestation.isNone:
return none(AggregateAndProof)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.1/specs/phase0/validator.md#construct-aggregate
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.1/specs/phase0/validator.md#aggregateandproof
some(AggregateAndProof(
aggregator_index: validatorIndex.uint64,
aggregate: maybe_slot_attestation.get,
selection_proof: slot_signature))