# beacon_chain # Copyright (c) 2018-2021 Status Research & Development GmbH # Licensed and distributed under either of # * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT). # * Apache v2 license (license terms in the root directory or at https://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/sequtils, stew/results, chronicles, ../extras, ../spec/[beaconstate, helpers, network, signatures, validator], ../spec/datatypes/base, ./block_pools_types, blockchain_dag export base, extras, block_pools_types, results # Spec functions implemented based on cached values instead of the full state func count_active_validators*(epochInfo: EpochRef): uint64 = epochInfo.shuffled_active_validator_indices.lenu64 # https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/phase0/beacon-chain.md#get_committee_count_per_slot func get_committee_count_per_slot*(epochInfo: EpochRef): uint64 = get_committee_count_per_slot(count_active_validators(epochInfo)) iterator get_committee_indices*(epochRef: EpochRef): CommitteeIndex = let committees_per_slot = get_committee_count_per_slot(epochRef) for committee_index in get_committee_indices(committees_per_slot): yield committee_index func get_committee_index*(epochRef: EpochRef, index: uint64): Result[CommitteeIndex, cstring] = check_attestation_index(index, get_committee_count_per_slot(epochRef)) # https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/phase0/beacon-chain.md#get_beacon_committee iterator get_beacon_committee*( epochRef: EpochRef, slot: Slot, committee_index: CommitteeIndex): (int, ValidatorIndex) = ## Return the beacon committee at ``slot`` for ``index``. let committees_per_slot = get_committee_count_per_slot(epochRef) for index_in_committee, idx in compute_committee( epochRef.shuffled_active_validator_indices, (slot mod SLOTS_PER_EPOCH) * committees_per_slot + committee_index.asUInt64, committees_per_slot * SLOTS_PER_EPOCH ): yield (index_in_committee, idx) # https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/phase0/beacon-chain.md#get_beacon_committee func get_beacon_committee*( epochRef: EpochRef, slot: Slot, committee_index: CommitteeIndex): seq[ValidatorIndex] = ## Return the beacon committee at ``slot`` for ``index``. let committees_per_slot = get_committee_count_per_slot(epochRef) compute_committee( epochRef.shuffled_active_validator_indices, (slot mod SLOTS_PER_EPOCH) * committees_per_slot + committee_index.asUInt64, committees_per_slot * SLOTS_PER_EPOCH ) # https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/phase0/beacon-chain.md#get_beacon_committee func get_beacon_committee_len*( epochRef: EpochRef, slot: Slot, committee_index: CommitteeIndex): uint64 = ## Return the number of members in the beacon committee at ``slot`` for ``index``. let committees_per_slot = get_committee_count_per_slot(epochRef) compute_committee_len( count_active_validators(epochRef), (slot mod SLOTS_PER_EPOCH) * committees_per_slot + committee_index.asUInt64, committees_per_slot * SLOTS_PER_EPOCH ) # https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/phase0/beacon-chain.md#get_attesting_indices iterator get_attesting_indices*(epochRef: EpochRef, slot: Slot, committee_index: CommitteeIndex, bits: CommitteeValidatorsBits): ValidatorIndex = if bits.lenu64 != get_beacon_committee_len(epochRef, slot, committee_index): trace "get_attesting_indices: inconsistent aggregation and committee length" else: for index_in_committee, validator_index in get_beacon_committee( epochRef, slot, committee_index).pairs(): if bits[index_in_committee]: yield validator_index func get_attesting_indices_one*(epochRef: EpochRef, slot: Slot, committee_index: CommitteeIndex, bits: CommitteeValidatorsBits): Option[ValidatorIndex] = # A variation on get_attesting_indices that returns the validator index only # if only one validator index is set var res = none(ValidatorIndex) for validator_index in get_attesting_indices( epochRef, slot, committee_index, bits): if res.isSome(): return none(ValidatorIndex) res = some(validator_index) res # https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/phase0/beacon-chain.md#get_attesting_indices func get_attesting_indices*(epochRef: EpochRef, slot: Slot, committee_index: CommitteeIndex, bits: CommitteeValidatorsBits): seq[ValidatorIndex] = # TODO sequtils2 mapIt for idx in get_attesting_indices(epochRef, slot, committee_index, bits): result.add(idx) # https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/phase0/beacon-chain.md#is_valid_indexed_attestation proc is_valid_indexed_attestation*( fork: Fork, genesis_validators_root: Eth2Digest, epochRef: EpochRef, attestation: SomeAttestation, flags: UpdateFlags): Result[void, cstring] = # This is a variation on `is_valid_indexed_attestation` that works directly # with an attestation instead of first constructing an `IndexedAttestation` # and then validating it - for the purpose of validating the signature, the # order doesn't matter and we can proceed straight to validating the # signature instead let sigs = attestation.aggregation_bits.countOnes() if sigs == 0: return err("is_valid_indexed_attestation: no attesting indices") # Verify aggregate signature if not (skipBLSValidation in flags or attestation.signature is TrustedSig): var pubkeys = newSeqOfCap[CookedPubKey](sigs) for index in get_attesting_indices( epochRef, attestation.data, attestation.aggregation_bits): pubkeys.add(epochRef.validatorKey(index).get()) if not verify_attestation_signature( fork, genesis_validators_root, attestation.data, pubkeys, attestation.signature): return err("is_valid_indexed_attestation: signature verification failure") ok() func makeAttestationData*( epochRef: EpochRef, bs: BlockSlot, committee_index: CommitteeIndex): AttestationData = ## Create an attestation / vote for the block `bs` using the ## data in `epochRef` to fill in the rest of the fields. ## `epochRef` is the epoch information corresponding to the `bs` advanced to ## the slot we're attesting to. let slot = bs.slot current_epoch = slot.epoch() epoch_boundary_slot = current_epoch.start_slot() epoch_boundary_block = bs.blck.atSlot(epoch_boundary_slot) doAssert current_epoch == epochRef.epoch # https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/phase0/validator.md#attestation-data AttestationData( slot: slot, index: committee_index.asUInt64, beacon_block_root: bs.blck.root, source: epochRef.current_justified_checkpoint, target: Checkpoint( epoch: current_epoch, root: epoch_boundary_block.blck.root ) ) # https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/phase0/validator.md#validator-assignments iterator get_committee_assignments*( epochRef: EpochRef, validator_indices: HashSet[ValidatorIndex]): tuple[committee_index: CommitteeIndex, subnet_id: SubnetId, slot: Slot] = let committees_per_slot = get_committee_count_per_slot(epochRef) epoch = epochRef.epoch for slot in epoch.slots(): for committee_index in get_committee_indices(committees_per_slot): if anyIt(get_beacon_committee(epochRef, slot, committee_index), it in validator_indices): yield ( committee_index, compute_subnet_for_attestation(committees_per_slot, slot, committee_index), slot) 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)