345 lines
15 KiB
Nim
345 lines
15 KiB
Nim
# beacon_chain
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# Copyright (c) 2018-2022 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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# Uncategorized helper functions from the spec
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{.push raises: [Defect].}
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# References to `vFuture` refer to the pre-release proposal of the libp2p based
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# light client sync protocol. Conflicting release versions are not in use.
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# https://github.com/ethereum/consensus-specs/pull/2802
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import
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# Standard lib
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std/[algorithm, math, sets, tables],
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# Status libraries
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stew/[bitops2, byteutils, endians2, objects],
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# Internal
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./datatypes/[phase0, altair, bellatrix],
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"."/[eth2_merkleization, forks, ssz_codec]
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# TODO although eth2_merkleization already exports ssz_codec, *sometimes* code
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# fails to compile if the export is not done here also
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export
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forks, eth2_merkleization, ssz_codec
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/beacon-chain.md#integer_squareroot
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func integer_squareroot*(n: SomeInteger): SomeInteger =
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## Return the largest integer ``x`` such that ``x**2 <= n``.
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doAssert n >= 0'u64
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var
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x = n
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y = (x + 1) div 2
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while y < x:
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x = y
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y = (x + n div x) div 2
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x
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/beacon-chain.md#is_active_validator
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func is_active_validator*(validator: Validator, epoch: Epoch): bool =
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## Check if ``validator`` is active
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validator.activation_epoch <= epoch and epoch < validator.exit_epoch
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func is_exited_validator*(validator: Validator, epoch: Epoch): bool =
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## Check if ``validator`` is exited
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validator.exit_epoch <= epoch
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func is_withdrawable_validator*(validator: Validator, epoch: Epoch): bool =
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epoch >= validator.withdrawable_epoch
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/beacon-chain.md#get_active_validator_indices
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iterator get_active_validator_indices*(state: ForkyBeaconState, epoch: Epoch):
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ValidatorIndex =
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for vidx in state.validators.vindices:
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if is_active_validator(state.validators[vidx], epoch):
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yield vidx
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func get_active_validator_indices*(state: ForkyBeaconState, epoch: Epoch):
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seq[ValidatorIndex] =
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## Return the sequence of active validator indices at ``epoch``.
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var res = newSeqOfCap[ValidatorIndex](state.validators.len)
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for vidx in get_active_validator_indices(state, epoch):
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res.add vidx
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res
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func get_active_validator_indices_len*(state: ForkyBeaconState, epoch: Epoch):
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uint64 =
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for vidx in state.validators.vindices:
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if is_active_validator(state.validators.item(vidx), epoch):
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inc result
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func get_active_validator_indices_len*(
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state: ForkedHashedBeaconState; epoch: Epoch): uint64 =
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withState(state):
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get_active_validator_indices_len(state.data, epoch)
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/beacon-chain.md#get_current_epoch
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func get_current_epoch*(state: ForkyBeaconState): Epoch =
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## Return the current epoch.
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state.slot.epoch
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/beacon-chain.md#get_current_epoch
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func get_current_epoch*(state: ForkedHashedBeaconState): Epoch =
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## Return the current epoch.
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withState(state): get_current_epoch(state.data)
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/beacon-chain.md#get_randao_mix
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func get_randao_mix*(state: ForkyBeaconState, epoch: Epoch): Eth2Digest =
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## Returns the randao mix at a recent ``epoch``.
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state.randao_mixes[epoch mod EPOCHS_PER_HISTORICAL_VECTOR]
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func bytes_to_uint64*(data: openArray[byte]): uint64 =
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doAssert data.len == 8
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# Little-endian data representation
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uint64.fromBytesLE(data)
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func uint_to_bytes*(x: uint64): array[8, byte] = toBytesLE(x)
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func uint_to_bytes*(x: uint32): array[4, byte] = toBytesLE(x)
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func uint_to_bytes*(x: uint16): array[2, byte] = toBytesLE(x)
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func uint_to_bytes*(x: uint8): array[1, byte] = toBytesLE(x)
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/beacon-chain.md#compute_domain
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func compute_domain*(
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domain_type: DomainType,
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fork_version: Version,
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genesis_validators_root: Eth2Digest = ZERO_HASH): Eth2Domain =
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## Return the domain for the ``domain_type`` and ``fork_version``.
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let fork_data_root =
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compute_fork_data_root(fork_version, genesis_validators_root)
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result[0..3] = domain_type.data
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result[4..31] = fork_data_root.data.toOpenArray(0, 27)
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/beacon-chain.md#get_domain
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func get_domain*(
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fork: Fork,
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domain_type: DomainType,
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epoch: Epoch,
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genesis_validators_root: Eth2Digest): Eth2Domain =
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## Return the signature domain (fork version concatenated with domain type)
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## of a message.
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let fork_version =
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if epoch < fork.epoch:
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fork.previous_version
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else:
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fork.current_version
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compute_domain(domain_type, fork_version, genesis_validators_root)
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func get_domain*(
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state: ForkyBeaconState, domain_type: DomainType, epoch: Epoch): Eth2Domain =
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## Return the signature domain (fork version concatenated with domain type)
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## of a message.
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get_domain(state.fork, domain_type, epoch, state.genesis_validators_root)
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/beacon-chain.md#compute_signing_root
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func compute_signing_root*(ssz_object: auto, domain: Eth2Domain): Eth2Digest =
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## Return the signing root of an object by calculating the root of the
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## object-domain tree.
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let domain_wrapped_object = SigningData(
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object_root: hash_tree_root(ssz_object),
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domain: domain
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)
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hash_tree_root(domain_wrapped_object)
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/beacon-chain.md#get_seed
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func get_seed*(state: ForkyBeaconState, epoch: Epoch, domain_type: DomainType):
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Eth2Digest =
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## Return the seed at ``epoch``.
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var seed_input : array[4+8+32, byte]
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# Detect potential underflow
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static:
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doAssert EPOCHS_PER_HISTORICAL_VECTOR > MIN_SEED_LOOKAHEAD
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seed_input[0..3] = domain_type.data
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seed_input[4..11] = uint_to_bytes(epoch.uint64)
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seed_input[12..43] =
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get_randao_mix(state, # Avoid underflow
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epoch + EPOCHS_PER_HISTORICAL_VECTOR - MIN_SEED_LOOKAHEAD - 1).data
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eth2digest(seed_input)
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/altair/beacon-chain.md#add_flag
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func add_flag*(flags: ParticipationFlags, flag_index: int): ParticipationFlags =
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let flag = ParticipationFlags(1'u8 shl flag_index)
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flags or flag
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/altair/beacon-chain.md#has_flag
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func has_flag*(flags: ParticipationFlags, flag_index: int): bool =
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let flag = ParticipationFlags(1'u8 shl flag_index)
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(flags and flag) == flag
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# https://github.com/ethereum/consensus-specs/blob/vFuture/specs/altair/sync-protocol.md#is_sync_committee_update
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template is_sync_committee_update*(update: SomeLightClientUpdate): bool =
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when update is SomeLightClientUpdateWithSyncCommittee:
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not isZeroMemory(update.next_sync_committee_branch)
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else:
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false
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/altair/sync-protocol.md#get_active_header
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template is_finality_update*(update: SomeLightClientUpdate): bool =
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when update is SomeLightClientUpdateWithFinality:
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not isZeroMemory(update.finality_branch)
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else:
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false
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# https://github.com/ethereum/consensus-specs/blob/vFuture/specs/altair/sync-protocol.md#is_next_sync_committee_known
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template is_next_sync_committee_known*(store: LightClientStore): bool =
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not isZeroMemory(store.next_sync_committee)
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/altair/sync-protocol.md#get_safety_threshold
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func get_safety_threshold*(store: LightClientStore): uint64 =
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max(
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store.previous_max_active_participants,
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store.current_max_active_participants
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) div 2
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# https://github.com/ethereum/consensus-specs/blob/vFuture/specs/altair/sync-protocol.md#is_better_update
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type LightClientUpdateMetadata* = object
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attested_slot*, finalized_slot*, signature_slot*: Slot
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has_sync_committee*, has_finality*: bool
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num_active_participants*: uint64
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func toMeta*(update: SomeLightClientUpdate): LightClientUpdateMetadata =
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var meta {.noinit.}: LightClientUpdateMetadata
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meta.attested_slot =
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update.attested_header.slot
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meta.finalized_slot =
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when update is SomeLightClientUpdateWithFinality:
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update.finalized_header.slot
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else:
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GENESIS_SLOT
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meta.signature_slot =
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update.signature_slot
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meta.has_sync_committee =
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when update is SomeLightClientUpdateWithSyncCommittee:
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not update.next_sync_committee_branch.isZeroMemory
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else:
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false
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meta.has_finality =
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when update is SomeLightClientUpdateWithFinality:
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not update.finality_branch.isZeroMemory
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else:
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false
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meta.num_active_participants =
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countOnes(update.sync_aggregate.sync_committee_bits).uint64
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meta
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func is_better_data*(new_meta, old_meta: LightClientUpdateMetadata): bool =
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# Compare supermajority (> 2/3) sync committee participation
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const max_active_participants = SYNC_COMMITTEE_SIZE.uint64
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let
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new_has_supermajority =
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new_meta.num_active_participants * 3 >= max_active_participants * 2
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old_has_supermajority =
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old_meta.num_active_participants * 3 >= max_active_participants * 2
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if new_has_supermajority != old_has_supermajority:
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return new_has_supermajority > old_has_supermajority
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if not new_has_supermajority:
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if new_meta.num_active_participants != old_meta.num_active_participants:
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return new_meta.num_active_participants > old_meta.num_active_participants
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# Compare presence of relevant sync committee
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let
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new_has_relevant_sync_committee = new_meta.has_sync_committee and
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new_meta.attested_slot.sync_committee_period ==
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new_meta.signature_slot.sync_committee_period
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old_has_relevant_sync_committee = old_meta.has_sync_committee and
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old_meta.attested_slot.sync_committee_period ==
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old_meta.signature_slot.sync_committee_period
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if new_has_relevant_sync_committee != old_has_relevant_sync_committee:
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return new_has_relevant_sync_committee > old_has_relevant_sync_committee
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# Compare indication of any finality
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if new_meta.has_finality != old_meta.has_finality:
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return new_meta.has_finality > old_meta.has_finality
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# Compare sync committee finality
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if new_meta.has_finality:
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let
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new_has_sync_committee_finality =
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new_meta.finalized_slot.sync_committee_period ==
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new_meta.attested_slot.sync_committee_period
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old_has_sync_committee_finality =
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old_meta.finalized_slot.sync_committee_period ==
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old_meta.attested_slot.sync_committee_period
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if new_has_sync_committee_finality != old_has_sync_committee_finality:
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return new_has_sync_committee_finality > old_has_sync_committee_finality
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# Tiebreaker 1: Sync committee participation beyond supermajority
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if new_meta.num_active_participants != old_meta.num_active_participants:
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return new_meta.num_active_participants > old_meta.num_active_participants
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# Tiebreaker 2: Prefer older data (fewer changes to best data)
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new_meta.attested_slot < old_meta.attested_slot
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template is_better_update*[A, B: SomeLightClientUpdate](
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new_update: A, old_update: B): bool =
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is_better_data(toMeta(new_update), toMeta(old_update))
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/bellatrix/beacon-chain.md#is_merge_transition_complete
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func is_merge_transition_complete*(state: bellatrix.BeaconState): bool =
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const defaultExecutionPayloadHeader = default(ExecutionPayloadHeader)
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state.latest_execution_payload_header != defaultExecutionPayloadHeader
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/sync/optimistic.md#helpers
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func is_execution_block*(
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body: bellatrix.BeaconBlockBody | bellatrix.TrustedBeaconBlockBody |
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bellatrix.SigVerifiedBeaconBlockBody): bool =
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const defaultBellatrixExecutionPayload = default(bellatrix.ExecutionPayload)
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body.execution_payload != defaultBellatrixExecutionPayload
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/bellatrix/beacon-chain.md#is_merge_transition_block
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func is_merge_transition_block(
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state: bellatrix.BeaconState,
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body: bellatrix.BeaconBlockBody | bellatrix.TrustedBeaconBlockBody |
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bellatrix.SigVerifiedBeaconBlockBody): bool =
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const defaultBellatrixExecutionPayload = default(bellatrix.ExecutionPayload)
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not is_merge_transition_complete(state) and
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body.execution_payload != defaultBellatrixExecutionPayload
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/bellatrix/beacon-chain.md#is_execution_enabled
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func is_execution_enabled*(
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state: bellatrix.BeaconState,
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body: bellatrix.BeaconBlockBody | bellatrix.TrustedBeaconBlockBody |
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bellatrix.SigVerifiedBeaconBlockBody): bool =
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is_merge_transition_block(state, body) or is_merge_transition_complete(state)
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# https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/bellatrix/beacon-chain.md#compute_timestamp_at_slot
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func compute_timestamp_at_slot*(state: ForkyBeaconState, slot: Slot): uint64 =
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# Note: This function is unsafe with respect to overflows and underflows.
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let slots_since_genesis = slot - GENESIS_SLOT
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state.genesis_time + slots_since_genesis * SECONDS_PER_SLOT
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# https://github.com/ethereum/consensus-specs/blob/v1.1.10/tests/core/pyspec/eth2spec/test/helpers/execution_payload.py#L1-L31
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func build_empty_execution_payload*(state: bellatrix.BeaconState): ExecutionPayload =
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## Assuming a pre-state of the same slot, build a valid ExecutionPayload
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## without any transactions.
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let
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latest = state.latest_execution_payload_header
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timestamp = compute_timestamp_at_slot(state, state.slot)
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randao_mix = get_randao_mix(state, get_current_epoch(state))
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var payload = ExecutionPayload(
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parent_hash: latest.block_hash,
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state_root: latest.state_root, # no changes to the state
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receipts_root: static(Eth2Digest.fromHex(
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"0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421")),
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block_number: latest.block_number + 1,
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prev_randao: randao_mix,
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gas_limit: latest.gas_limit, # retain same limit
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gas_used: 0, # empty block, 0 gas
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timestamp: timestamp,
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base_fee_per_gas: latest.base_fee_per_gas) # retain same base_fee
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payload.block_hash = withEth2Hash:
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h.update payload.hash_tree_root().data
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h.update cast[array[13, uint8]]("FAKE RLP HASH")
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payload
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