nimbus-eth2/beacon_chain/consensus_object_pools/spec_cache.nim

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# 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,
chronicles,
../extras,
../spec/[helpers, network, signatures, validator],
../spec/datatypes/base,
./block_pools_types, blockchain_dag
export
base, extras, block_pools_types
# 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/v1.1.6/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 =
for i in 0'u64..<get_committee_count_per_slot(epochRef):
yield CommitteeIndex(i)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_beacon_committee
iterator get_beacon_committee*(
epochRef: EpochRef, slot: Slot, index: CommitteeIndex): ValidatorIndex =
## Return the beacon committee at ``slot`` for ``index``.
let
committees_per_slot = get_committee_count_per_slot(epochRef)
for idx in compute_committee(
epochRef.shuffled_active_validator_indices,
(slot mod SLOTS_PER_EPOCH) * committees_per_slot +
index.uint64,
committees_per_slot * SLOTS_PER_EPOCH
): yield idx
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_beacon_committee
func get_beacon_committee*(
epochRef: EpochRef, slot: Slot, 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 +
index.uint64,
committees_per_slot * SLOTS_PER_EPOCH
)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_beacon_committee
func get_beacon_committee_len*(
epochRef: EpochRef, slot: Slot, 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 +
index.uint64,
committees_per_slot * SLOTS_PER_EPOCH
)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_attesting_indices
iterator get_attesting_indices*(epochRef: EpochRef,
data: AttestationData,
bits: CommitteeValidatorsBits):
ValidatorIndex =
if bits.lenu64 != get_beacon_committee_len(epochRef, data.slot, data.index.CommitteeIndex):
trace "get_attesting_indices: inconsistent aggregation and committee length"
else:
var i = 0
for index in get_beacon_committee(epochRef, data.slot, data.index.CommitteeIndex):
if bits[i]:
yield index
inc i
func get_attesting_indices_one*(epochRef: EpochRef,
data: AttestationData,
bits: CommitteeValidatorsBits):
Option[ValidatorIndex] =
# A variation on get_attesting_indices that returns the validator index only
# if only one validator index is set
if bits.lenu64 != get_beacon_committee_len(epochRef, data.slot, data.index.CommitteeIndex):
trace "get_attesting_indices: inconsistent aggregation and committee length"
none(ValidatorIndex)
else:
var res = none(ValidatorIndex)
var i = 0
for index in get_beacon_committee(epochRef, data.slot, data.index.CommitteeIndex):
if bits[i]:
if res.isNone():
res = some(index)
else:
return none(ValidatorIndex)
inc i
res
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_attesting_indices
func get_attesting_indices*(epochRef: EpochRef,
data: AttestationData,
bits: CommitteeValidatorsBits):
seq[ValidatorIndex] =
# TODO sequtils2 mapIt
for idx in get_attesting_indices(epochRef, data, bits):
result.add(idx)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/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()
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func makeAttestationData*(
epochRef: EpochRef, bs: BlockSlot,
committee_index: CommitteeIndex): AttestationData =
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## 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.compute_epoch_at_slot()
epoch_boundary_slot = compute_start_slot_at_epoch(current_epoch)
epoch_boundary_block = bs.blck.atSlot(epoch_boundary_slot)
doAssert current_epoch == epochRef.epoch
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/validator.md#attestation-data
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AttestationData(
slot: slot,
index: committee_index.uint64,
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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/v1.1.6/specs/phase0/validator.md#validator-assignments
iterator get_committee_assignments*(
epochRef: EpochRef, validator_indices: HashSet[ValidatorIndex]):
tuple[subcommitteeIdx: CommitteeIndex,
subnet_id: SubnetId, slot: Slot] =
let
committees_per_slot = get_committee_count_per_slot(epochRef)
epoch = epochRef.epoch
start_slot = compute_start_slot_at_epoch(epoch)
for slot in start_slot ..< start_slot + SLOTS_PER_EPOCH:
for index in 0'u64 ..< committees_per_slot:
let
idx = index.CommitteeIndex
if anyIt(
get_beacon_committee(epochRef, slot, idx), it in validator_indices):
yield (
idx,
compute_subnet_for_attestation(committees_per_slot, slot, idx),
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)