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nimbus-eth2/beacon_chain/spec/beaconstate.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/[algorithm, collections/heapqueue, math, options, sequtils, tables],
stew/assign2,
json_serialization/std/sets,
chronicles,
../extras,
./datatypes/[phase0, altair, merge],
"."/[eth2_merkleization, forks, signatures, validator]
export extras, forks, validator
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#increase_balance
func increase_balance*(balance: var Gwei, delta: Gwei) =
balance += delta
func increase_balance*(
state: var ForkyBeaconState, index: ValidatorIndex, delta: Gwei) =
## Increase the validator balance at index ``index`` by ``delta``.
if delta != 0: # avoid dirtying the balance cache if not needed
increase_balance(state.balances[index], delta)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#decrease_balance
func decrease_balance*(balance: var Gwei, delta: Gwei) =
balance =
if delta > balance:
0'u64
else:
balance - delta
func decrease_balance*(
state: var ForkyBeaconState, index: ValidatorIndex, delta: Gwei) =
## Decrease the validator balance at index ``index`` by ``delta``, with
## underflow protection.
if delta != 0: # avoid dirtying the balance cache if not needed
decrease_balance(state.balances[index], delta)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#deposits
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/altair/beacon-chain.md#modified-process_deposit
func get_validator_from_deposit*(deposit: DepositData):
Validator =
let
amount = deposit.amount
effective_balance = min(
amount - amount mod EFFECTIVE_BALANCE_INCREMENT, MAX_EFFECTIVE_BALANCE)
Validator(
pubkey: deposit.pubkey,
withdrawal_credentials: deposit.withdrawal_credentials,
activation_eligibility_epoch: FAR_FUTURE_EPOCH,
activation_epoch: FAR_FUTURE_EPOCH,
exit_epoch: FAR_FUTURE_EPOCH,
withdrawable_epoch: FAR_FUTURE_EPOCH,
effective_balance: effective_balance
)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#compute_activation_exit_epoch
func compute_activation_exit_epoch*(epoch: Epoch): Epoch =
## Return the epoch during which validator activations and exits initiated in
## ``epoch`` take effect.
epoch + 1 + MAX_SEED_LOOKAHEAD
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_validator_churn_limit
func get_validator_churn_limit*(
cfg: RuntimeConfig, state: ForkyBeaconState, cache: var StateCache):
uint64 =
## Return the validator churn limit for the current epoch.
max(
cfg.MIN_PER_EPOCH_CHURN_LIMIT,
count_active_validators(
state, state.get_current_epoch(), cache) div cfg.CHURN_LIMIT_QUOTIENT)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#initiate_validator_exit
func initiate_validator_exit*(cfg: RuntimeConfig, state: var ForkyBeaconState,
index: ValidatorIndex, cache: var StateCache) =
## Initiate the exit of the validator with index ``index``.
if state.validators.asSeq()[index].exit_epoch != FAR_FUTURE_EPOCH:
return # Before touching cache
# Return if validator already initiated exit
let validator = addr state.validators[index]
trace "Validator exiting",
index = index,
num_validators = state.validators.len,
current_epoch = get_current_epoch(state),
validator_slashed = validator.slashed,
validator_withdrawable_epoch = validator.withdrawable_epoch,
validator_exit_epoch = validator.exit_epoch,
validator_effective_balance = validator.effective_balance
var exit_queue_epoch = compute_activation_exit_epoch(get_current_epoch(state))
# Compute max exit epoch
for idx in 0..<state.validators.len:
let exit_epoch = state.validators.asSeq()[idx].exit_epoch
if exit_epoch != FAR_FUTURE_EPOCH and exit_epoch > exit_queue_epoch:
exit_queue_epoch = exit_epoch
var
exit_queue_churn: int
for idx in 0..<state.validators.len:
if state.validators.asSeq()[idx].exit_epoch == exit_queue_epoch:
exit_queue_churn += 1
if exit_queue_churn.uint64 >= get_validator_churn_limit(cfg, state, cache):
exit_queue_epoch += 1
# Set validator exit epoch and withdrawable epoch
validator.exit_epoch = exit_queue_epoch
validator.withdrawable_epoch =
validator.exit_epoch + cfg.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#slash_validator
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/altair/beacon-chain.md#modified-slash_validator
# https://github.com/ethereum/consensus-specs/blob/v1.1.4/specs/merge/beacon-chain.md#modified-slash_validator
proc slash_validator*(
cfg: RuntimeConfig, state: var ForkyBeaconState,
slashed_index: ValidatorIndex, cache: var StateCache) =
## Slash the validator with index ``index``.
let epoch = get_current_epoch(state)
initiate_validator_exit(cfg, state, slashed_index, cache)
let validator = addr state.validators[slashed_index]
trace "slash_validator: ejecting validator via slashing (validator_leaving)",
index = slashed_index,
num_validators = state.validators.len,
current_epoch = get_current_epoch(state),
validator_slashed = validator.slashed,
validator_withdrawable_epoch = validator.withdrawable_epoch,
validator_exit_epoch = validator.exit_epoch,
validator_effective_balance = validator.effective_balance
validator.slashed = true
validator.withdrawable_epoch =
max(validator.withdrawable_epoch, epoch + EPOCHS_PER_SLASHINGS_VECTOR)
state.slashings[int(epoch mod EPOCHS_PER_SLASHINGS_VECTOR)] +=
validator.effective_balance
# TODO Consider whether this is better than splitting the functions apart; in
# each case, tradeoffs. Here, it's just changing a couple of constants.
when state is phase0.BeaconState:
decrease_balance(state, slashed_index,
validator.effective_balance div MIN_SLASHING_PENALTY_QUOTIENT)
elif state is altair.BeaconState:
decrease_balance(state, slashed_index,
validator.effective_balance div MIN_SLASHING_PENALTY_QUOTIENT_ALTAIR)
elif state is merge.BeaconState:
decrease_balance(state, slashed_index,
validator.effective_balance div MIN_SLASHING_PENALTY_QUOTIENT_MERGE)
else:
raiseAssert "invalid BeaconState type"
# The rest doesn't make sense without there being any proposer index, so skip
let proposer_index = get_beacon_proposer_index(state, cache)
if proposer_index.isNone:
debug "No beacon proposer index and probably no active validators"
return
# Apply proposer and whistleblower rewards
let
# Spec has whistleblower_index as optional param, but it's never used.
whistleblower_index = proposer_index.get
whistleblower_reward =
(validator.effective_balance div WHISTLEBLOWER_REWARD_QUOTIENT).Gwei
proposer_reward =
when state is phase0.BeaconState:
whistleblower_reward div PROPOSER_REWARD_QUOTIENT
elif state is altair.BeaconState or state is merge.BeaconState:
whistleblower_reward * PROPOSER_WEIGHT div WEIGHT_DENOMINATOR
else:
raiseAssert "invalid BeaconState type"
increase_balance(state, proposer_index.get, proposer_reward)
# TODO: evaluate if spec bug / underflow can be triggered
doAssert(whistleblower_reward >= proposer_reward, "Spec bug: underflow in slash_validator")
increase_balance(
state, whistleblower_index, whistleblower_reward - proposer_reward)
func genesis_time_from_eth1_timestamp*(cfg: RuntimeConfig, eth1_timestamp: uint64): uint64 =
eth1_timestamp + cfg.GENESIS_DELAY
# https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/beacon-chain.md#genesis
proc initialize_beacon_state_from_eth1*(
cfg: RuntimeConfig,
eth1_block_hash: Eth2Digest,
eth1_timestamp: uint64,
deposits: openArray[DepositData],
flags: UpdateFlags = {}): phase0.BeaconState =
## Get the genesis ``BeaconState``.
##
## Before the beacon chain starts, validators will register in the Eth1 chain
## and deposit ETH. When enough many validators have registered, a
## `ChainStart` log will be emitted and the beacon chain can start beaconing.
##
## Because the state root hash is part of the genesis block, the beacon state
## must be calculated before creating the genesis block.
# Induct validators
# Not in spec: the system doesn't work unless there are at least SLOTS_PER_EPOCH
# validators - there needs to be at least one member in each committee -
# good to know for testing, though arguably the system is not that useful at
# at that point :)
doAssert deposits.lenu64 >= SLOTS_PER_EPOCH
# TODO https://github.com/nim-lang/Nim/issues/19094
template state(): untyped = result
state = phase0.BeaconState(
fork: genesisFork(cfg),
genesis_time: genesis_time_from_eth1_timestamp(cfg, eth1_timestamp),
eth1_data:
Eth1Data(block_hash: eth1_block_hash, deposit_count: uint64(len(deposits))),
latest_block_header:
BeaconBlockHeader(
body_root: hash_tree_root(default(phase0.BeaconBlockBody))))
# Seed RANDAO with Eth1 entropy
state.randao_mixes.fill(eth1_block_hash)
var merkleizer = createMerkleizer(2'i64^DEPOSIT_CONTRACT_TREE_DEPTH)
for i, deposit in deposits:
let htr = hash_tree_root(deposit)
merkleizer.addChunk(htr.data)
# This is already known in the Eth1 monitor, but it would be too
# much work to refactor all the existing call sites in the test suite
state.eth1_data.deposit_root = mixInLength(merkleizer.getFinalHash(),
deposits.len)
state.eth1_deposit_index = deposits.lenu64
var pubkeyToIndex = initTable[ValidatorPubKey, ValidatorIndex]()
for idx, deposit in deposits:
let
pubkey = deposit.pubkey
amount = deposit.amount
pubkeyToIndex.withValue(pubkey, foundIdx) do:
# Increase balance by deposit amount
increase_balance(state, ValidatorIndex foundIdx[], amount)
do:
if skipBlsValidation in flags or
verify_deposit_signature(cfg, deposit):
pubkeyToIndex[pubkey] = ValidatorIndex(state.validators.len)
if not state.validators.add(get_validator_from_deposit(deposit)):
raiseAssert "too many validators"
if not state.balances.add(amount):
raiseAssert "same as validators"
else:
# Invalid deposits are perfectly possible
trace "Skipping deposit with invalid signature",
deposit = shortLog(deposit)
# Process activations
for validator_index in 0 ..< state.validators.len:
let
balance = state.balances.asSeq()[validator_index]
validator = addr state.validators[validator_index]
validator.effective_balance = min(
balance - balance mod EFFECTIVE_BALANCE_INCREMENT, MAX_EFFECTIVE_BALANCE)
if validator.effective_balance == MAX_EFFECTIVE_BALANCE:
validator.activation_eligibility_epoch = GENESIS_EPOCH
validator.activation_epoch = GENESIS_EPOCH
# Set genesis validators root for domain separation and chain versioning
state.genesis_validators_root = hash_tree_root(state.validators)
# TODO https://github.com/nim-lang/Nim/issues/19094
# state
proc initialize_hashed_beacon_state_from_eth1*(
cfg: RuntimeConfig,
eth1_block_hash: Eth2Digest,
eth1_timestamp: uint64,
deposits: openArray[DepositData],
flags: UpdateFlags = {}): phase0.HashedBeaconState =
# TODO https://github.com/nim-lang/Nim/issues/19094
result = phase0.HashedBeaconState(
data: initialize_beacon_state_from_eth1(
cfg, eth1_block_hash, eth1_timestamp, deposits, flags))
result.root = hash_tree_root(result.data)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#genesis-block
func get_initial_beacon_block*(state: phase0.HashedBeaconState):
phase0.TrustedSignedBeaconBlock =
# The genesis block is implicitly trusted
let message = phase0.TrustedBeaconBlock(
slot: state.data.slot,
state_root: state.root)
# parent_root, randao_reveal, eth1_data, signature, and body automatically
# initialized to default values.
phase0.TrustedSignedBeaconBlock(
message: message, root: hash_tree_root(message))
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/altair/beacon-chain.md#initialize-state-for-pure-altair-testnets-and-test-vectors
func get_initial_beacon_block*(state: altair.HashedBeaconState):
altair.TrustedSignedBeaconBlock =
# The genesis block is implicitly trusted
let message = altair.TrustedBeaconBlock(
slot: state.data.slot,
state_root: state.root)
# parent_root, randao_reveal, eth1_data, signature, and body automatically
# initialized to default values.
altair.TrustedSignedBeaconBlock(
message: message, root: hash_tree_root(message))
# https://github.com/ethereum/consensus-specs/blob/v1.1.5/specs/merge/beacon-chain.md#testing
func get_initial_beacon_block*(state: merge.HashedBeaconState):
merge.TrustedSignedBeaconBlock =
# The genesis block is implicitly trusted
let message = merge.TrustedBeaconBlock(
slot: state.data.slot,
state_root: state.root,)
# parent_root, randao_reveal, eth1_data, signature, and body automatically
# initialized to default values.
merge.TrustedSignedBeaconBlock(
message: message, root: hash_tree_root(message))
func get_initial_beacon_block*(state: ForkedHashedBeaconState):
ForkedTrustedSignedBeaconBlock =
withState(state):
ForkedTrustedSignedBeaconBlock.init(get_initial_beacon_block(state))
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_block_root_at_slot
func get_block_root_at_slot*(state: ForkyBeaconState, slot: Slot): Eth2Digest =
## Return the block root at a recent ``slot``.
# Potential overflow/wrap shouldn't occur, as get_block_root_at_slot() called
# from internally controlled sources, but flag this explicitly, in case.
doAssert slot + SLOTS_PER_HISTORICAL_ROOT > slot
doAssert state.slot <= slot + SLOTS_PER_HISTORICAL_ROOT
doAssert slot < state.slot
state.block_roots[slot mod SLOTS_PER_HISTORICAL_ROOT]
func get_block_root_at_slot*(state: ForkedHashedBeaconState,
slot: Slot): Eth2Digest =
## Return the block root at a recent ``slot``.
withState(state):
get_block_root_at_slot(state.data, slot)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_block_root
func get_block_root*(state: ForkyBeaconState, epoch: Epoch): Eth2Digest =
## Return the block root at the start of a recent ``epoch``.
get_block_root_at_slot(state, compute_start_slot_at_epoch(epoch))
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_total_balance
template get_total_balance(
state: ForkyBeaconState, validator_indices: untyped): Gwei =
## Return the combined effective balance of the ``indices``.
## ``EFFECTIVE_BALANCE_INCREMENT`` Gwei minimum to avoid divisions by zero.
## Math safe up to ~10B ETH, afterwhich this overflows uint64.
var res = 0.Gwei
for validator_index in validator_indices:
res += state.validators.asSeq()[validator_index].effective_balance
max(EFFECTIVE_BALANCE_INCREMENT, res)
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#is_eligible_for_activation_queue
func is_eligible_for_activation_queue*(validator: Validator): bool =
## Check if ``validator`` is eligible to be placed into the activation queue.
validator.activation_eligibility_epoch == FAR_FUTURE_EPOCH and
validator.effective_balance == MAX_EFFECTIVE_BALANCE
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#is_eligible_for_activation
func is_eligible_for_activation*(state: ForkyBeaconState, validator: Validator):
bool =
## Check if ``validator`` is eligible for activation.
# Placement in queue is finalized
validator.activation_eligibility_epoch <= state.finalized_checkpoint.epoch and
# Has not yet been activated
validator.activation_epoch == FAR_FUTURE_EPOCH
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#is_valid_indexed_attestation
proc is_valid_indexed_attestation*(
state: ForkyBeaconState, indexed_attestation: SomeIndexedAttestation,
flags: UpdateFlags): Result[void, cstring] =
## Check if ``indexed_attestation`` is not empty, has sorted and unique
## indices and has a valid aggregate signature.
template is_sorted_and_unique(s: untyped): bool =
var res = true
for i in 1 ..< s.len:
if s[i - 1].uint64 >= s[i].uint64:
res = false
break
res
if len(indexed_attestation.attesting_indices) == 0:
return err("indexed_attestation: no attesting indices")
# Not from spec, but this function gets used in front-line roles, not just
# behind firewall.
let num_validators = state.validators.lenu64
if anyIt(indexed_attestation.attesting_indices, it >= num_validators):
return err("indexed attestation: not all indices valid validators")
if not is_sorted_and_unique(indexed_attestation.attesting_indices):
return err("indexed attestation: indices not sorted and unique")
# Verify aggregate signature
if not (skipBLSValidation in flags or indexed_attestation.signature is TrustedSig):
let pubkeys = mapIt(
indexed_attestation.attesting_indices, state.validators[it].pubkey)
if not verify_attestation_signature(
state.fork, state.genesis_validators_root, indexed_attestation.data,
pubkeys, indexed_attestation.signature):
return err("indexed attestation: signature verification failure")
ok()
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_attesting_indices
func get_attesting_indices*(state: ForkyBeaconState,
data: AttestationData,
bits: CommitteeValidatorsBits,
cache: var StateCache): seq[ValidatorIndex] =
## Return the set of attesting indices corresponding to ``data`` and ``bits``.
var res: seq[ValidatorIndex]
# Can't be an iterator due to https://github.com/nim-lang/Nim/issues/18188
if bits.lenu64 != get_beacon_committee_len(
state, data.slot, data.index.CommitteeIndex, cache):
trace "get_attesting_indices: inconsistent aggregation and committee length"
else:
var i = 0
for index in get_beacon_committee(
state, data.slot, data.index.CommitteeIndex, cache):
if bits[i]:
res.add index
inc i
res
proc get_attesting_indices*(state: ForkedHashedBeaconState;
data: AttestationData;
bits: CommitteeValidatorsBits;
cache: var StateCache): seq[ValidatorIndex] =
# TODO when https://github.com/nim-lang/Nim/issues/18188 fixed, use an
# iterator
var idxBuf: seq[ValidatorIndex]
withState(state):
for vidx in state.data.get_attesting_indices(data, bits, cache):
idxBuf.add vidx
idxBuf
proc is_valid_indexed_attestation*(
state: ForkyBeaconState, attestation: SomeAttestation, flags: UpdateFlags,
cache: var StateCache): 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[ValidatorPubKey](sigs)
for index in get_attesting_indices(
state, attestation.data, attestation.aggregation_bits, cache):
pubkeys.add(state.validators[index].pubkey)
if not verify_attestation_signature(
state.fork, state.genesis_validators_root, attestation.data,
pubkeys, attestation.signature):
return err("indexed attestation: signature verification failure")
ok()
# Attestation validation
# ------------------------------------------------------------------------------------------
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#attestations
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/p2p-interface.md#beacon_attestation_subnet_id
func check_attestation_slot_target*(data: AttestationData): Result[void, cstring] =
if not (data.target.epoch == compute_epoch_at_slot(data.slot)):
return err("Target epoch doesn't match attestation slot")
ok()
func check_attestation_target_epoch(
data: AttestationData, current_epoch: Epoch): Result[void, cstring] =
if not (data.target.epoch == get_previous_epoch(current_epoch) or
data.target.epoch == current_epoch):
return err("Target epoch not current or previous epoch")
ok()
func check_attestation_inclusion(data: AttestationData,
current_slot: Slot): Result[void, cstring] =
# Check for overflow
static:
doAssert SLOTS_PER_EPOCH >= MIN_ATTESTATION_INCLUSION_DELAY
if data.slot + SLOTS_PER_EPOCH <= data.slot:
return err("attestation data.slot overflow, malicious?")
if not (data.slot + MIN_ATTESTATION_INCLUSION_DELAY <= current_slot):
return err("Attestation too new")
if not (current_slot <= data.slot + SLOTS_PER_EPOCH):
return err("Attestation too old")
ok()
func check_attestation_index(
data: AttestationData, committees_per_slot: uint64): Result[void, cstring] =
if not (data.index < committees_per_slot):
return err("Data index exceeds committee count")
ok()
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/altair/beacon-chain.md#get_attestation_participation_flag_indices
func get_attestation_participation_flag_indices(state: altair.BeaconState | merge.BeaconState,
data: AttestationData,
inclusion_delay: uint64): seq[int] =
## Return the flag indices that are satisfied by an attestation.
let justified_checkpoint =
if data.target.epoch == get_current_epoch(state):
state.current_justified_checkpoint
else:
state.previous_justified_checkpoint
# Matching roots
let
is_matching_source = data.source == justified_checkpoint
is_matching_target = is_matching_source and data.target.root == get_block_root(state, data.target.epoch)
is_matching_head = is_matching_target and data.beacon_block_root == get_block_root_at_slot(state, data.slot)
# TODO probably this needs to be robustly failable
doAssert is_matching_source
var participation_flag_indices: seq[int]
if is_matching_source and inclusion_delay <= integer_squareroot(SLOTS_PER_EPOCH):
participation_flag_indices.add(TIMELY_SOURCE_FLAG_INDEX)
if is_matching_target and inclusion_delay <= SLOTS_PER_EPOCH:
participation_flag_indices.add(TIMELY_TARGET_FLAG_INDEX)
if is_matching_head and inclusion_delay == MIN_ATTESTATION_INCLUSION_DELAY:
participation_flag_indices.add(TIMELY_HEAD_FLAG_INDEX)
participation_flag_indices
# TODO these aren't great here
# TODO these duplicate some stuff in state_transition_epoch which uses TotalBalances
# better to centralize around that if feasible
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#get_total_active_balance
func get_total_active_balance*(state: ForkyBeaconState, cache: var StateCache): Gwei =
## Return the combined effective balance of the active validators.
# Note: ``get_total_balance`` returns ``EFFECTIVE_BALANCE_INCREMENT`` Gwei
# minimum to avoid divisions by zero.
let epoch = state.get_current_epoch()
get_total_balance(
state, cache.get_shuffled_active_validator_indices(state, epoch))
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/altair/beacon-chain.md#get_base_reward_per_increment
func get_base_reward_per_increment_sqrt*(
total_active_balance_sqrt: uint64): Gwei =
EFFECTIVE_BALANCE_INCREMENT * BASE_REWARD_FACTOR div total_active_balance_sqrt
func get_base_reward_per_increment*(
total_active_balance: Gwei): Gwei =
get_base_reward_per_increment_sqrt(integer_squareroot(total_active_balance))
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/altair/beacon-chain.md#get_base_reward
func get_base_reward(
state: altair.BeaconState | merge.BeaconState, index: ValidatorIndex,
base_reward_per_increment: Gwei): Gwei =
## Return the base reward for the validator defined by ``index`` with respect
## to the current ``state``.
let increments =
state.validators[index].effective_balance div EFFECTIVE_BALANCE_INCREMENT
increments * base_reward_per_increment
# https://github.com/ethereum/consensus-specs/blob/v1.1.0/specs/phase0/beacon-chain.md#attestations
proc check_attestation*(
state: ForkyBeaconState, attestation: SomeAttestation, flags: UpdateFlags,
cache: var StateCache): Result[void, cstring] =
## Check that an attestation follows the rules of being included in the state
## at the current slot. When acting as a proposer, the same rules need to
## be followed!
let
data = attestation.data
? check_attestation_target_epoch(data, state.get_current_epoch())
? check_attestation_slot_target(data)
? check_attestation_inclusion(data, state.slot)
? check_attestation_index(
data,
get_committee_count_per_slot(state, data.target.epoch, cache))
let committee_len = get_beacon_committee_len(
state, data.slot, data.index.CommitteeIndex, cache)
if attestation.aggregation_bits.lenu64 != committee_len:
return err("Inconsistent aggregation and committee length")
if data.target.epoch == get_current_epoch(state):
if not (data.source == state.current_justified_checkpoint):
return err("FFG data not matching current justified epoch")
else:
if not (data.source == state.previous_justified_checkpoint):
return err("FFG data not matching previous justified epoch")
? is_valid_indexed_attestation(state, attestation, flags, cache)
ok()
proc process_attestation*(
state: var ForkyBeaconState, attestation: SomeAttestation, flags: UpdateFlags,
base_reward_per_increment: Gwei, cache: var StateCache):
Result[void, cstring] =
# In the spec, attestation validation is mixed with state mutation, so here
# we've split it into two functions so that the validation logic can be
# reused when looking for suitable blocks to include in attestations.
#
# TODO this should be two separate functions, but
# https://github.com/nim-lang/Nim/issues/18202 means that this being called
# by process_operations() in state_transition_block fails that way.
let proposer_index = get_beacon_proposer_index(state, cache)
if proposer_index.isNone:
return err("process_attestation: no beacon proposer index and probably no active validators")
? check_attestation(state, attestation, flags, cache)
# For phase0
template addPendingAttestation(attestations: typed) =
# The genericSeqAssign generated by the compiler to copy the attestation
# data sadly is a processing hotspot - the business with the addDefault
# pointer is here simply to work around the poor codegen
var pa = attestations.addDefault()
if pa.isNil:
return err("process_attestation: too many pending attestations")
assign(pa[].aggregation_bits, attestation.aggregation_bits)
pa[].data = attestation.data
pa[].inclusion_delay = state.slot - attestation.data.slot
pa[].proposer_index = proposer_index.get().uint64
# Altair and Merge
template updateParticipationFlags(epoch_participation: untyped) =
var proposer_reward_numerator = 0'u64
# Participation flag indices
let participation_flag_indices =
get_attestation_participation_flag_indices(
state, attestation.data, state.slot - attestation.data.slot)
for index in get_attesting_indices(
state, attestation.data, attestation.aggregation_bits, cache):
for flag_index, weight in PARTICIPATION_FLAG_WEIGHTS:
if flag_index in participation_flag_indices and
not has_flag(epoch_participation.asSeq[index], flag_index):
epoch_participation.asSeq[index] =
add_flag(epoch_participation.asSeq[index], flag_index)
# these are all valid; TODO statically verify or do it type-safely
proposer_reward_numerator += get_base_reward(
state, index, base_reward_per_increment) * weight.uint64
epoch_participation.clearCache()
# Reward proposer
let
# TODO use correct type at source
proposer_reward_denominator = (WEIGHT_DENOMINATOR.uint64 - PROPOSER_WEIGHT.uint64) * WEIGHT_DENOMINATOR.uint64 div PROPOSER_WEIGHT.uint64
proposer_reward = Gwei(proposer_reward_numerator div proposer_reward_denominator)
increase_balance(state, proposer_index.get, proposer_reward)
when state is phase0.BeaconState:
doAssert base_reward_per_increment == 0.Gwei
if attestation.data.target.epoch == get_current_epoch(state):
addPendingAttestation(state.current_epoch_attestations)
else:
addPendingAttestation(state.previous_epoch_attestations)
elif state is altair.BeaconState or state is merge.BeaconState:
doAssert base_reward_per_increment > 0.Gwei
if attestation.data.target.epoch == get_current_epoch(state):
updateParticipationFlags(state.current_epoch_participation)
else:
updateParticipationFlags(state.previous_epoch_participation)
else:
static: doAssert false
ok()
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/altair/beacon-chain.md#get_next_sync_committee_indices
func get_next_sync_committee_keys(state: altair.BeaconState | merge.BeaconState):
array[SYNC_COMMITTEE_SIZE, ValidatorPubKey] =
## Return the sequence of sync committee indices (which may include
## duplicate indices) for the next sync committee, given a ``state`` at a
## sync committee period boundary.
# The sync committe depends on seed and effective balance - it can
# thus only be computed for the current epoch of the state, after balance
# updates have been performed
let epoch = get_current_epoch(state) + 1
const MAX_RANDOM_BYTE = 255
let
active_validator_indices = get_active_validator_indices(state, epoch)
active_validator_count = uint64(len(active_validator_indices))
seed = get_seed(state, epoch, DOMAIN_SYNC_COMMITTEE)
var
i = 0'u64
index = 0
res: array[SYNC_COMMITTEE_SIZE, ValidatorPubKey]
hash_buffer: array[40, byte]
hash_buffer[0..31] = seed.data
while index < SYNC_COMMITTEE_SIZE:
hash_buffer[32..39] = uint_to_bytes8(uint64(i div 32))
let
shuffled_index = compute_shuffled_index(uint64(i mod active_validator_count), active_validator_count, seed)
candidate_index = active_validator_indices[shuffled_index]
random_byte = eth2digest(hash_buffer).data[i mod 32]
effective_balance = state.validators[candidate_index].effective_balance
if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE * random_byte:
res[index] = state.validators[candidate_index].pubkey
inc index
i += 1'u64
res
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/altair/beacon-chain.md#get_next_sync_committee
proc get_next_sync_committee*(state: altair.BeaconState | merge.BeaconState):
SyncCommittee =
## Return the *next* sync committee for a given ``state``.
var res: SyncCommittee
res.pubkeys.data = get_next_sync_committee_keys(state)
# see signatures_batch, TODO shouldn't be here
# Deposit processing ensures all keys are valid
var attestersAgg: AggregatePublicKey
attestersAgg.init(res.pubkeys.data[0].load().get)
for i in 1 ..< res.pubkeys.data.len:
attestersAgg.aggregate(res.pubkeys.data[i].load().get)
res.aggregate_pubkey = finish(attestersAgg).toPubKey()
res
# https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/altair/fork.md#upgrading-the-state
func translate_participation(
state: var altair.BeaconState,
pending_attestations: openArray[phase0.PendingAttestation]) =
var cache = StateCache()
for attestation in pending_attestations:
let
data = attestation.data
inclusion_delay = attestation.inclusion_delay
# Translate attestation inclusion info to flag indices
participation_flag_indices =
get_attestation_participation_flag_indices(state, data, inclusion_delay)
# Apply flags to all attesting validators
for index in get_attesting_indices(
state, data, attestation.aggregation_bits, cache):
for flag_index in participation_flag_indices:
state.previous_epoch_participation[index] =
add_flag(state.previous_epoch_participation[index], flag_index)
proc upgrade_to_altair*(cfg: RuntimeConfig, pre: phase0.BeaconState): ref altair.BeaconState =
var
empty_participation =
HashList[ParticipationFlags, Limit VALIDATOR_REGISTRY_LIMIT]()
inactivity_scores = HashList[uint64, Limit VALIDATOR_REGISTRY_LIMIT]()
doAssert empty_participation.data.setLen(pre.validators.len)
empty_participation.resetCache()
doAssert inactivity_scores.data.setLen(pre.validators.len)
inactivity_scores.resetCache()
var post = (ref altair.BeaconState)(
genesis_time: pre.genesis_time,
genesis_validators_root: pre.genesis_validators_root,
slot: pre.slot,
fork: altairFork(cfg),
# History
latest_block_header: pre.latest_block_header,
block_roots: pre.block_roots,
state_roots: pre.state_roots,
historical_roots: pre.historical_roots,
# Eth1
eth1_data: pre.eth1_data,
eth1_data_votes: pre.eth1_data_votes,
eth1_deposit_index: pre.eth1_deposit_index,
# Registry
validators: pre.validators,
balances: pre.balances,
# Randomness
randao_mixes: pre.randao_mixes,
# Slashings
slashings: pre.slashings,
# Attestations
previous_epoch_participation: empty_participation,
current_epoch_participation: empty_participation,
# Finality
justification_bits: pre.justification_bits,
previous_justified_checkpoint: pre.previous_justified_checkpoint,
current_justified_checkpoint: pre.current_justified_checkpoint,
finalized_checkpoint: pre.finalized_checkpoint,
# Inactivity
inactivity_scores: inactivity_scores
)
# Fill in previous epoch participation from the pre state's pending
# attestations
translate_participation(post[], pre.previous_epoch_attestations.asSeq)
# Fill in sync committees
# Note: A duplicate committee is assigned for the current and next committee
# at the fork boundary
post[].current_sync_committee = get_next_sync_committee(post[])
post[].next_sync_committee = get_next_sync_committee(post[])
post
# https://github.com/ethereum/consensus-specs/blob/v1.1.4/specs/merge/fork.md#upgrading-the-state
func upgrade_to_merge*(cfg: RuntimeConfig, pre: altair.BeaconState):
ref merge.BeaconState =
let epoch = get_current_epoch(pre)
(ref merge.BeaconState)(
# Versioning
genesis_time: pre.genesis_time,
genesis_validators_root: pre.genesis_validators_root,
slot: pre.slot,
fork: Fork(
previous_version: pre.fork.current_version,
current_version: cfg.MERGE_FORK_VERSION,
epoch: epoch,
),
# History
latest_block_header: pre.latest_block_header,
block_roots: pre.block_roots,
state_roots: pre.state_roots,
historical_roots: pre.historical_roots,
# Eth1
eth1_data: pre.eth1_data,
eth1_data_votes: pre.eth1_data_votes,
eth1_deposit_index: pre.eth1_deposit_index,
# Registry
validators: pre.validators,
balances: pre.balances,
# Randomness
randao_mixes: pre.randao_mixes,
# Slashings
slashings: pre.slashings,
# Participation
previous_epoch_participation: pre.previous_epoch_participation,
current_epoch_participation: pre.current_epoch_participation,
# Finality
justification_bits: pre.justification_bits,
previous_justified_checkpoint: pre.previous_justified_checkpoint,
current_justified_checkpoint: pre.current_justified_checkpoint,
finalized_checkpoint: pre.finalized_checkpoint,
# Inactivity
inactivity_scores: pre.inactivity_scores,
# Sync
current_sync_committee: pre.current_sync_committee,
next_sync_committee: pre.next_sync_committee,
# Execution-layer
latest_execution_payload_header: ExecutionPayloadHeader()
)
template isValidInState*(idx: ValidatorIndex, state: ForkyBeaconState): bool =
idx.uint64 < state.validators.lenu64
func latest_block_root*(state: ForkyBeaconState, state_root: Eth2Digest): Eth2Digest =
# The root of the last block that was successfully applied to this state -
# normally, when a block is applied, the data from the header is stored in
# the state without the state root - on the next process_slot, the state root
# is added to the header and the block root can now be computed and added to
# the block roots table. If process_slot has not yet run on top of the new
# block, we must fill in the state root ourselves.
if state.slot == state.latest_block_header.slot:
# process_slot will not yet have updated the header of the "current" block -
# similar to block creation, we fill it in with the state root
var tmp = state.latest_block_header
tmp.state_root = state_root
hash_tree_root(tmp)
elif state.slot <=
(state.latest_block_header.slot + SLOTS_PER_HISTORICAL_ROOT):
# block_roots is limited to about a day - see assert in
# `get_block_root_at_slot`
state.get_block_root_at_slot(state.latest_block_header.slot)
else:
# Reallly long periods of empty slots - unlikely but possible
hash_tree_root(state.latest_block_header)
func latest_block_root*(state: ForkyHashedBeaconState): Eth2Digest =
latest_block_root(state.data, state.root)
func get_sync_committee_cache*(
state: altair.BeaconState | merge.BeaconState, cache: var StateCache):
SyncCommitteeCache =
let period = state.slot.sync_committee_period()
cache.sync_committees.withValue(period, v) do:
return v[]
var
s = toHashSet(state.current_sync_committee.pubkeys.data)
for pk in state.next_sync_committee.pubkeys.data:
s.incl(pk)
var pubkeyIndices: Table[ValidatorPubKey, ValidatorIndex]
for i, v in state.validators:
if v.pubkey in s:
pubkeyIndices[v.pubkey] = i.ValidatorIndex
var res: SyncCommitteeCache
try:
for i in 0..<res.current_sync_committee.len():
res.current_sync_committee[i] =
pubkeyIndices[state.current_sync_committee.pubkeys[i]]
res.next_sync_committee[i] =
pubkeyIndices[state.next_sync_committee.pubkeys[i]]
except KeyError:
raiseAssert "table constructed just above"
cache.sync_committees[period] = res
res
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