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Split state_transition (#301)

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Mamy Ratsimbazafy 2019-06-28 15:44:44 +02:00 committed by Dustin Brody
parent 0d37ed7a2a
commit 214860cb88
3 changed files with 925 additions and 847 deletions
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# beacon_chain
# Copyright (c) 2018-2019 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.
# State transition - block processing, as described in
# https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
#
# The purpose of this code right is primarily educational, to help piece
# together the mechanics of the beacon state and to discover potential problem
# areas.
#
# The entry point is `process_block` which is at the bottom of this file.
#
# General notes about the code (TODO):
# * It's inefficient - we quadratically copy, allocate and iterate when there
# are faster options
# * Weird styling - the sections taken from the spec use python styling while
# the others use NEP-1 - helps grepping identifiers in spec
# * We mix procedural and functional styles for no good reason, except that the
# spec does so also.
# * There are likely lots of bugs.
# * For indices, we get a mix of uint64, ValidatorIndex and int - this is currently
# swept under the rug with casts
# * The spec uses uint64 for data types, but functions in the spec often assume
# signed bigint semantics - under- and overflows ensue
# * Sane error handling is missing in most cases (yay, we'll get the chance to
# debate exceptions again!)
# When updating the code, add TODO sections to mark where there are clear
# improvements to be made - other than that, keep things similar to spec for
# now.
import # TODO - cleanup imports
algorithm, collections/sets, chronicles, math, options, sequtils, sets, tables,
../extras, ../ssz, ../beacon_node_types,
beaconstate, bitfield, crypto, datatypes, digest, helpers, validator
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#block-header
proc processBlockHeader(
state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags,
stateCache: var StateCache): bool =
# Verify that the slots match
if not (blck.slot == state.slot):
notice "Block header: slot mismatch",
block_slot = humaneSlotNum(blck.slot),
state_slot = humaneSlotNum(state.slot)
return false
# Verify that the parent matches
if skipValidation notin flags and not (blck.parent_root ==
signing_root(state.latest_block_header)):
notice "Block header: previous block root mismatch",
latest_block_header = state.latest_block_header,
blck = shortLog(blck),
latest_block_header_root = shortLog(signing_root(state.latest_block_header))
return false
# Save current block as the new latest block
state.latest_block_header = BeaconBlockHeader(
slot: blck.slot,
parent_root: blck.parent_root,
body_root: hash_tree_root(blck.body),
)
# Verify proposer is not slashed
let proposer =
state.validator_registry[get_beacon_proposer_index(state, stateCache)]
if proposer.slashed:
notice "Block header: proposer slashed"
return false
# Verify proposer signature
if skipValidation notin flags and not bls_verify(
proposer.pubkey,
signing_root(blck).data,
blck.signature,
get_domain(state, DOMAIN_BEACON_PROPOSER)):
notice "Block header: invalid block header",
proposer_pubkey = proposer.pubkey,
block_root = shortLog(signing_root(blck)),
block_signature = blck.signature
return false
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#randao
proc processRandao(
state: var BeaconState, body: BeaconBlockBody, flags: UpdateFlags,
stateCache: var StateCache): bool =
let
proposer_index = get_beacon_proposer_index(state, stateCache)
proposer = addr state.validator_registry[proposer_index]
# Verify that the provided randao value is valid
if skipValidation notin flags:
if not bls_verify(
proposer.pubkey,
hash_tree_root(get_current_epoch(state).uint64).data,
body.randao_reveal,
get_domain(state, DOMAIN_RANDAO)):
notice "Randao mismatch", proposer_pubkey = proposer.pubkey,
message = get_current_epoch(state),
signature = body.randao_reveal,
slot = state.slot
return false
# Mix it in
let
mix = get_current_epoch(state) mod LATEST_RANDAO_MIXES_LENGTH
rr = eth2hash(body.randao_reveal.getBytes()).data
for i, b in state.latest_randao_mixes[mix].data:
state.latest_randao_mixes[mix].data[i] = b xor rr[i]
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#eth1-data
func processEth1Data(state: var BeaconState, body: BeaconBlockBody) =
state.eth1_data_votes.add body.eth1_data
if state.eth1_data_votes.count(body.eth1_data) * 2 >
SLOTS_PER_ETH1_VOTING_PERIOD:
state.latest_eth1_data = body.eth1_data
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#is_slashable_validator
func is_slashable_validator(validator: Validator, epoch: Epoch): bool =
# Check if ``validator`` is slashable.
(not validator.slashed) and
(validator.activation_epoch <= epoch) and
(epoch < validator.withdrawable_epoch)
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#proposer-slashings
proc processProposerSlashings(
state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags,
stateCache: var StateCache): bool =
if len(blck.body.proposer_slashings) > MAX_PROPOSER_SLASHINGS:
notice "PropSlash: too many!",
proposer_slashings = len(blck.body.proposer_slashings)
return false
for proposer_slashing in blck.body.proposer_slashings:
let proposer = state.validator_registry[proposer_slashing.proposer_index.int]
# Verify that the epoch is the same
if not (slot_to_epoch(proposer_slashing.header_1.slot) ==
slot_to_epoch(proposer_slashing.header_2.slot)):
notice "PropSlash: epoch mismatch"
return false
# But the headers are different
if not (proposer_slashing.header_1 != proposer_slashing.header_2):
notice "PropSlash: headers not different"
return false
# Check proposer is slashable
if not is_slashable_validator(proposer, get_current_epoch(state)):
notice "PropSlash: slashed proposer"
return false
# Signatures are valid
if skipValidation notin flags:
for i, header in @[proposer_slashing.header_1, proposer_slashing.header_2]:
if not bls_verify(
proposer.pubkey,
signing_root(header).data,
header.signature,
get_domain(
state, DOMAIN_BEACON_PROPOSER, slot_to_epoch(header.slot))):
notice "PropSlash: invalid signature",
signature_index = i
return false
slashValidator(
state, proposer_slashing.proposer_index.ValidatorIndex, stateCache)
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#is_slashable_attestation_data
func is_slashable_attestation_data(
data_1: AttestationData, data_2: AttestationData): bool =
## Check if ``data_1`` and ``data_2`` are slashable according to Casper FFG
## rules.
# Double vote
(data_1 != data_2 and data_1.target_epoch == data_2.target_epoch) or
# Surround vote
(data_1.source_epoch < data_2.source_epoch and
data_2.target_epoch < data_1.target_epoch)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#attester-slashings
proc processAttesterSlashings(state: var BeaconState, blck: BeaconBlock,
stateCache: var StateCache): bool =
# Process ``AttesterSlashing`` operation.
if len(blck.body.attester_slashings) > MAX_ATTESTER_SLASHINGS:
notice "CaspSlash: too many!"
return false
result = true
for attester_slashing in blck.body.attester_slashings:
let
attestation_1 = attester_slashing.attestation_1
attestation_2 = attester_slashing.attestation_2
if not is_slashable_attestation_data(
attestation_1.data, attestation_2.data):
notice "CaspSlash: surround or double vote check failed"
return false
if not validate_indexed_attestation(state, attestation_1):
notice "CaspSlash: invalid votes 1"
return false
if not validate_indexed_attestation(state, attestation_2):
notice "CaspSlash: invalid votes 2"
return false
var slashed_any = false
## TODO there's a lot of sorting/set construction here and
## verify_indexed_attestation, but go by spec unless there
## is compelling perf evidence otherwise.
let attesting_indices_1 =
attestation_1.custody_bit_0_indices & attestation_1.custody_bit_1_indices
let attesting_indices_2 =
attestation_2.custody_bit_0_indices & attestation_2.custody_bit_1_indices
for index in sorted(toSeq(intersection(toSet(attesting_indices_1),
toSet(attesting_indices_2)).items), system.cmp):
if is_slashable_validator(state.validator_registry[index.int],
get_current_epoch(state)):
slash_validator(state, index.ValidatorIndex, stateCache)
slashed_any = true
result = result and slashed_any
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#attestations
proc processAttestations(
state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags,
stateCache: var StateCache): bool =
## Each block includes a number of attestations that the proposer chose. Each
## attestation represents an update to a specific shard and is signed by a
## committee of validators.
## Here we make sanity checks for each attestation and it to the state - most
## updates will happen at the epoch boundary where state updates happen in
## bulk.
if blck.body.attestations.len > MAX_ATTESTATIONS:
notice "Attestation: too many!", attestations = blck.body.attestations.len
return false
if not blck.body.attestations.allIt(checkAttestation(state, it, flags, stateCache)):
return false
# All checks passed - update state
# Apply the attestations
var committee_count_cache = initTable[Epoch, uint64]()
for attestation in blck.body.attestations:
# Caching
let
epoch = attestation.data.target_epoch
committee_count = if epoch in committee_count_cache:
committee_count_cache[epoch]
else:
get_epoch_committee_count(state, epoch)
committee_count_cache[epoch] = committee_count
# Spec content
let attestation_slot =
get_attestation_data_slot(state, attestation.data, committee_count)
let pending_attestation = PendingAttestation(
data: attestation.data,
aggregation_bitfield: attestation.aggregation_bitfield,
inclusion_delay: state.slot - attestation_slot,
proposer_index: get_beacon_proposer_index(state, stateCache),
)
if attestation.data.target_epoch == get_current_epoch(state):
state.current_epoch_attestations.add(pending_attestation)
else:
state.previous_epoch_attestations.add(pending_attestation)
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.5.1/specs/core/0_beacon-chain.md#deposits
proc processDeposits(state: var BeaconState, blck: BeaconBlock): bool =
if not (len(blck.body.deposits) <= MAX_DEPOSITS):
notice "processDeposits: too many deposits"
return false
for deposit in blck.body.deposits:
if not process_deposit(state, deposit):
notice "processDeposits: deposit invalid"
return false
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#voluntary-exits
proc processVoluntaryExits(
state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags): bool =
# Process ``VoluntaryExit`` transaction.
if len(blck.body.voluntary_exits) > MAX_VOLUNTARY_EXITS:
notice "Exit: too many!"
return false
for exit in blck.body.voluntary_exits:
let validator = state.validator_registry[exit.validator_index.int]
# Verify the validator is active
if not is_active_validator(validator, get_current_epoch(state)):
notice "Exit: validator not active"
return false
# Verify the validator has not yet exited
if not (validator.exit_epoch == FAR_FUTURE_EPOCH):
notice "Exit: validator has exited"
return false
## Exits must specify an epoch when they become valid; they are not valid
## before then
if not (get_current_epoch(state) >= exit.epoch):
notice "Exit: exit epoch not passed"
return false
# Verify the validator has been active long enough
# TODO detect underflow
if not (get_current_epoch(state) - validator.activation_epoch >=
PERSISTENT_COMMITTEE_PERIOD):
notice "Exit: not in validator set long enough"
return false
# Verify signature
if skipValidation notin flags:
if not bls_verify(
validator.pubkey, signing_root(exit).data, exit.signature,
get_domain(state, DOMAIN_VOLUNTARY_EXIT, exit.epoch)):
notice "Exit: invalid signature"
return false
# Initiate exit
initiate_validator_exit(state, exit.validator_index.ValidatorIndex)
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#transfers
proc processTransfers(state: var BeaconState, blck: BeaconBlock,
flags: UpdateFlags, stateCache: var StateCache): bool =
if not (len(blck.body.transfers) <= MAX_TRANSFERS):
notice "Transfer: too many transfers"
return false
for transfer in blck.body.transfers:
let sender_balance = state.balances[transfer.sender.int]
## Verify the amount and fee are not individually too big (for anti-overflow
## purposes)
if not (sender_balance >= max(transfer.amount, transfer.fee)):
notice "Transfer: sender balance too low for transfer amount or fee"
return false
# A transfer is valid in only one slot
if not (state.slot == transfer.slot):
notice "Transfer: slot mismatch"
return false
## Sender must be not yet eligible for activation, withdrawn, or transfer
## balance over MAX_EFFECTIVE_BALANCE
if not (
state.validator_registry[transfer.sender.int].activation_epoch ==
FAR_FUTURE_EPOCH or
get_current_epoch(state) >=
state.validator_registry[
transfer.sender.int].withdrawable_epoch or
transfer.amount + transfer.fee + MAX_EFFECTIVE_BALANCE <=
state.balances[transfer.sender.int]):
notice "Transfer: only withdrawn or not-activated accounts with sufficient balance can transfer"
return false
# Verify that the pubkey is valid
let wc = state.validator_registry[transfer.sender.int].
withdrawal_credentials
if not (wc.data[0] == BLS_WITHDRAWAL_PREFIX and
wc.data[1..^1] == eth2hash(transfer.pubkey.getBytes).data[1..^1]):
notice "Transfer: incorrect withdrawal credentials"
return false
# Verify that the signature is valid
if skipValidation notin flags:
if not bls_verify(
transfer.pubkey, signing_root(transfer).data, transfer.signature,
get_domain(state, DOMAIN_TRANSFER)):
notice "Transfer: incorrect signature"
return false
# Process the transfer
decrease_balance(
state, transfer.sender.ValidatorIndex, transfer.amount + transfer.fee)
increase_balance(
state, transfer.recipient.ValidatorIndex, transfer.amount)
increase_balance(
state, get_beacon_proposer_index(state, stateCache), transfer.fee)
# Verify balances are not dust
if not (
0'u64 < state.balances[transfer.sender.int] and
state.balances[transfer.sender.int] < MIN_DEPOSIT_AMOUNT):
notice "Transfer: sender balance too low for transfer amount or fee"
return false
if not (
0'u64 < state.balances[transfer.recipient.int] and
state.balances[transfer.recipient.int] < MIN_DEPOSIT_AMOUNT):
notice "Transfer: sender balance too low for transfer amount or fee"
return false
true
proc processBlock*(
state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags,
stateCache: var StateCache): bool =
## When there's a new block, we need to verify that the block is sane and
## update the state accordingly
# TODO when there's a failure, we should reset the state!
# TODO probably better to do all verification first, then apply state changes
if not processBlockHeader(state, blck, flags, stateCache):
notice "Block header not valid", slot = humaneSlotNum(state.slot)
return false
if not processRandao(state, blck.body, flags, stateCache):
debug "[Block processing] Randao failure", slot = humaneSlotNum(state.slot)
return false
processEth1Data(state, blck.body)
if not processProposerSlashings(state, blck, flags, stateCache):
debug "[Block processing] Proposer slashing failure", slot = humaneSlotNum(state.slot)
return false
if not processAttesterSlashings(state, blck, stateCache):
debug "[Block processing] Attester slashing failure", slot = humaneSlotNum(state.slot)
return false
if not processAttestations(state, blck, flags, stateCache):
debug "[Block processing] Attestation processing failure", slot = humaneSlotNum(state.slot)
return false
if not processDeposits(state, blck):
debug "[Block processing] Deposit processing failure", slot = humaneSlotNum(state.slot)
return false
if not processVoluntaryExits(state, blck, flags):
debug "[Block processing] Exit processing failure", slot = humaneSlotNum(state.slot)
return false
if not processTransfers(state, blck, flags, stateCache):
debug "[Block processing] Transfer processing failure", slot = humaneSlotNum(state.slot)
return false
true

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# beacon_chain
# Copyright (c) 2018-2019 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.
# State transition - epoch processing, as described in
# https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
#
# The purpose of this code right is primarily educational, to help piece
# together the mechanics of the beacon state and to discover potential problem
# areas.
#
# The entry point is `process_epoch` which is at the bottom of this file.
#
# General notes about the code (TODO):
# * It's inefficient - we quadratically copy, allocate and iterate when there
# are faster options
# * Weird styling - the sections taken from the spec use python styling while
# the others use NEP-1 - helps grepping identifiers in spec
# * We mix procedural and functional styles for no good reason, except that the
# spec does so also.
# * There are likely lots of bugs.
# * For indices, we get a mix of uint64, ValidatorIndex and int - this is currently
# swept under the rug with casts
# * The spec uses uint64 for data types, but functions in the spec often assume
# signed bigint semantics - under- and overflows ensue
# * Sane error handling is missing in most cases (yay, we'll get the chance to
# debate exceptions again!)
# When updating the code, add TODO sections to mark where there are clear
# improvements to be made - other than that, keep things similar to spec for
# now.
import # TODO - cleanup imports
algorithm, collections/sets, chronicles, math, options, sequtils, sets, tables,
../extras, ../ssz, ../beacon_node_types,
beaconstate, bitfield, crypto, datatypes, digest, helpers, validator
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#helper-functions-1
func get_total_active_balance(state: BeaconState): Gwei =
return get_total_balance(
state,
get_active_validator_indices(state, get_current_epoch(state)))
func get_matching_source_attestations(state: BeaconState, epoch: Epoch):
seq[PendingAttestation] =
doAssert epoch in @[get_current_epoch(state), get_previous_epoch(state)]
if epoch == get_current_epoch(state):
state.current_epoch_attestations
else:
state.previous_epoch_attestations
func get_matching_target_attestations(state: BeaconState, epoch: Epoch):
seq[PendingAttestation] =
filterIt(
get_matching_source_attestations(state, epoch),
it.data.target_root == get_block_root(state, epoch)
)
func get_matching_head_attestations(state: BeaconState, epoch: Epoch):
seq[PendingAttestation] =
filterIt(
get_matching_source_attestations(state, epoch),
it.data.beacon_block_root ==
get_block_root_at_slot(state, get_attestation_data_slot(state, it.data))
)
func get_unslashed_attesting_indices(
state: BeaconState, attestations: seq[PendingAttestation],
stateCache: var StateCache): HashSet[ValidatorIndex] =
result = initSet[ValidatorIndex]()
for a in attestations:
result = result.union(get_attesting_indices(
state, a.data, a.aggregation_bitfield, stateCache))
for index in result:
if state.validator_registry[index].slashed:
result.excl index
func get_attesting_balance(
state: BeaconState, attestations: seq[PendingAttestation],
stateCache: var StateCache): Gwei =
get_total_balance(state, get_unslashed_attesting_indices(
state, attestations, stateCache))
# Not exactly in spec, but for get_winning_crosslink_and_attesting_indices
func lowerThan(candidate, current: Eth2Digest): bool =
# return true iff candidate is "lower" than current, per spec rule:
# "ties broken in favor of lexicographically higher hash
for i, v in current.data:
if v > candidate.data[i]: return true
false
func get_winning_crosslink_and_attesting_indices(
state: BeaconState, epoch: Epoch, shard: Shard,
stateCache: var StateCache): tuple[a: Crosslink, b: HashSet[ValidatorIndex]] =
let
attestations =
filterIt(
get_matching_source_attestations(state, epoch),
it.data.crosslink.shard == shard)
# TODO don't keep h_t_r'ing state.current_crosslinks[shard]
crosslinks =
filterIt(
mapIt(attestations, it.data.crosslink),
hash_tree_root(state.current_crosslinks[shard]) in
# TODO pointless memory allocation, etc.
@[it.parent_root, hash_tree_root(it)])
# default=Crosslink()
if len(crosslinks) == 0:
return (Crosslink(), initSet[ValidatorIndex]())
## Winning crosslink has the crosslink data root with the most balance voting
## for it (ties broken lexicographically)
var
winning_crosslink: Crosslink
winning_crosslink_balance = 0.Gwei
for candidate_crosslink in crosslinks:
## TODO check if should cache this again
## let root_balance = get_attesting_balance_cached(
## state, attestations_for.getOrDefault(r), cache)
let crosslink_balance =
get_attesting_balance(
state,
filterIt(attestations, it.data.crosslink == candidate_crosslink),
stateCache)
if (crosslink_balance > winning_crosslink_balance or
(winning_crosslink_balance == crosslink_balance and
lowerThan(winning_crosslink.data_root,
candidate_crosslink.data_root))):
winning_crosslink = candidate_crosslink
winning_crosslink_balance = crosslink_balance
let winning_attestations =
filterIt(attestations, it.data.crosslink == winning_crosslink)
(winning_crosslink,
get_unslashed_attesting_indices(state, winning_attestations, stateCache))
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#justification-and-finalization
func process_justification_and_finalization(
state: var BeaconState, stateCache: var StateCache) =
if get_current_epoch(state) <= GENESIS_EPOCH + 1:
return
let
previous_epoch = get_previous_epoch(state)
current_epoch = get_current_epoch(state)
old_previous_justified_epoch = state.previous_justified_epoch
old_current_justified_epoch = state.current_justified_epoch
# Process justifications
state.previous_justified_epoch = state.current_justified_epoch
state.previous_justified_root = state.current_justified_root
state.justification_bitfield = (state.justification_bitfield shl 1)
let previous_epoch_matching_target_balance =
get_attesting_balance(state,
get_matching_target_attestations(state, previous_epoch), stateCache)
if previous_epoch_matching_target_balance * 3 >=
get_total_active_balance(state) * 2:
state.current_justified_epoch = previous_epoch
state.current_justified_root =
get_block_root(state, state.current_justified_epoch)
state.justification_bitfield = state.justification_bitfield or (1 shl 1)
let current_epoch_matching_target_balance =
get_attesting_balance(state,
get_matching_target_attestations(state, current_epoch),
stateCache)
if current_epoch_matching_target_balance * 3 >=
get_total_active_balance(state) * 2:
state.current_justified_epoch = current_epoch
state.current_justified_root =
get_block_root(state, state.current_justified_epoch)
state.justification_bitfield = state.justification_bitfield or (1 shl 0)
# Process finalizations
let bitfield = state.justification_bitfield
## The 2nd/3rd/4th most recent epochs are justified, the 2nd using the 4th
## as source
if (bitfield shr 1) mod 8 == 0b111 and old_previous_justified_epoch + 3 ==
current_epoch:
state.finalized_epoch = old_previous_justified_epoch
state.finalized_root = get_block_root(state, state.finalized_epoch)
## The 2nd/3rd most recent epochs are justified, the 2nd using the 3rd as
## source
if (bitfield shr 1) mod 4 == 0b11 and old_previous_justified_epoch + 2 ==
current_epoch:
state.finalized_epoch = old_previous_justified_epoch
state.finalized_root = get_block_root(state, state.finalized_epoch)
## The 1st/2nd/3rd most recent epochs are justified, the 1st using the 3rd as
## source
if (bitfield shr 0) mod 8 == 0b111 and old_current_justified_epoch + 2 ==
current_epoch:
state.finalized_epoch = old_current_justified_epoch
state.finalized_root = get_block_root(state, state.finalized_epoch)
## The 1st/2nd most recent epochs are justified, the 1st using the 2nd as
## source
if (bitfield shr 0) mod 4 == 0b11 and old_current_justified_epoch + 1 ==
current_epoch:
state.finalized_epoch = old_current_justified_epoch
state.finalized_root = get_block_root(state, state.finalized_epoch)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#crosslinks
func process_crosslinks(state: var BeaconState, stateCache: var StateCache) =
## TODO is there a semantic reason for this, or is this just a way to force
## copying? If so, why not just `list(foo)` or similar? This is strange. In
## this case, for type reasons, don't do weird
## [c for c in state.current_crosslinks] from spec.
state.previous_crosslinks = state.current_crosslinks
for epoch_int in get_previous_epoch(state).uint64 ..
get_current_epoch(state).uint64:
# This issue comes up regularly -- iterating means an int type,
# which then needs re-conversion back to specialized type.
let epoch = epoch_int.Epoch
for offset in 0'u64 ..< get_epoch_committee_count(state, epoch):
let
shard = (get_epoch_start_shard(state, epoch) + offset) mod SHARD_COUNT
crosslink_committee =
get_crosslink_committee(state, epoch, shard, stateCache)
# In general, it'll loop over the same shards twice, and
# get_winning_root_and_participants is defined to return
# the same results from the previous epoch as current.
# TODO cache like before, in 0.5 version of this function
(winning_crosslink, attesting_indices) =
get_winning_crosslink_and_attesting_indices(
state, epoch, shard, stateCache)
if 3'u64 * get_total_balance(state, attesting_indices) >=
2'u64 * get_total_balance(state, crosslink_committee):
state.current_crosslinks[shard] = winning_crosslink
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#rewards-and-penalties-1
func get_base_reward(state: BeaconState, index: ValidatorIndex): Gwei =
let
total_balance = get_total_active_balance(state)
effective_balance = state.validator_registry[index].effective_balance
effective_balance * BASE_REWARD_FACTOR div
integer_squareroot(total_balance) div BASE_REWARDS_PER_EPOCH
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#rewards-and-penalties
func get_attestation_deltas(state: BeaconState, stateCache: var StateCache):
tuple[a: seq[Gwei], b: seq[Gwei]] =
let
previous_epoch = get_previous_epoch(state)
total_balance = get_total_active_balance(state)
var
rewards = repeat(0'u64, len(state.validator_registry))
penalties = repeat(0'u64, len(state.validator_registry))
eligible_validator_indices : seq[ValidatorIndex] = @[]
for index, v in state.validator_registry:
if is_active_validator(v, previous_epoch) or
(v.slashed and previous_epoch + 1 < v.withdrawable_epoch):
eligible_validator_indices.add index.ValidatorIndex
# Micro-incentives for matching FFG source, FFG target, and head
let
matching_source_attestations =
get_matching_source_attestations(state, previous_epoch)
matching_target_attestations =
get_matching_target_attestations(state, previous_epoch)
matching_head_attestations =
get_matching_head_attestations(state, previous_epoch)
for attestations in
@[matching_source_attestations, matching_target_attestations,
matching_head_attestations]:
let
unslashed_attesting_indices =
get_unslashed_attesting_indices(state, attestations, stateCache)
attesting_balance = get_attesting_balance(state, attestations, stateCache)
for index in eligible_validator_indices:
if index in unslashed_attesting_indices:
rewards[index] +=
get_base_reward(state, index) * attesting_balance div total_balance
else:
penalties[index] += get_base_reward(state, index)
if matching_source_attestations.len == 0:
return (rewards, penalties)
# Proposer and inclusion delay micro-rewards
for index in get_unslashed_attesting_indices(
state, matching_source_attestations, stateCache):
doAssert matching_source_attestations.len > 0
var attestation = matching_source_attestations[0]
for a in matching_source_attestations:
if index notin get_attesting_indices(
state, a.data, a.aggregation_bitfield, stateCache):
continue
if a.inclusion_delay < attestation.inclusion_delay:
attestation = a
rewards[attestation.proposer_index] += get_base_reward(state, index) div
PROPOSER_REWARD_QUOTIENT
rewards[index] +=
get_base_reward(state, index) * MIN_ATTESTATION_INCLUSION_DELAY div
attestation.inclusion_delay
# Inactivity penalty
let finality_delay = previous_epoch - state.finalized_epoch
if finality_delay > MIN_EPOCHS_TO_INACTIVITY_PENALTY:
let matching_target_attesting_indices =
get_unslashed_attesting_indices(
state, matching_target_attestations, stateCache)
for index in eligible_validator_indices:
penalties[index] +=
BASE_REWARDS_PER_EPOCH.uint64 * get_base_reward(state, index)
if index notin matching_target_attesting_indices:
penalties[index] +=
state.validator_registry[index].effective_balance *
finality_delay div INACTIVITY_PENALTY_QUOTIENT
(rewards, penalties)
# TODO re-cache this one, as under 0.5 version, if profiling suggests it
func get_crosslink_deltas(state: BeaconState, cache: var StateCache):
tuple[a: seq[Gwei], b: seq[Gwei]] =
var
rewards = repeat(0'u64, len(state.validator_registry))
penalties = repeat(0'u64, len(state.validator_registry))
let epoch = get_previous_epoch(state)
for offset in 0'u64 ..< get_epoch_committee_count(state, epoch):
let
shard = (get_epoch_start_shard(state, epoch) + offset) mod SHARD_COUNT
crosslink_committee =
get_crosslink_committee(state, epoch, shard, cache)
(winning_crosslink, attesting_indices) =
get_winning_crosslink_and_attesting_indices(
state, epoch, shard, cache)
attesting_balance = get_total_balance(state, attesting_indices)
committee_balance = get_total_balance(state, crosslink_committee)
for index in crosslink_committee:
let base_reward = get_base_reward(state, index)
if index in attesting_indices:
rewards[index] +=
get_base_reward(state, index) * attesting_balance div
committee_balance
else:
penalties[index] += get_base_reward(state, index)
(rewards, penalties)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#rewards-and-penalties-1
func process_rewards_and_penalties(
state: var BeaconState, cache: var StateCache) =
if get_current_epoch(state) == GENESIS_EPOCH:
return
let
(rewards1, penalties1) = get_attestation_deltas(state, cache)
(rewards2, penalties2) = get_crosslink_deltas(state, cache)
for i in 0 ..< len(state.validator_registry):
increase_balance(state, i.ValidatorIndex, rewards1[i] + rewards2[i])
decrease_balance(state, i.ValidatorIndex, penalties1[i] + penalties2[i])
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#slashings
func process_slashings(state: var BeaconState) =
let
current_epoch = get_current_epoch(state)
total_balance = get_total_active_balance(state)
# Compute `total_penalties`
total_at_start = state.latest_slashed_balances[
(current_epoch + 1) mod LATEST_SLASHED_EXIT_LENGTH]
total_at_end =
state.latest_slashed_balances[current_epoch mod
LATEST_SLASHED_EXIT_LENGTH]
total_penalties = total_at_end - total_at_start
for index, validator in state.validator_registry:
if validator.slashed and current_epoch == validator.withdrawable_epoch -
LATEST_SLASHED_EXIT_LENGTH div 2:
let
penalty = max(
validator.effective_balance *
min(total_penalties * 3, total_balance) div total_balance,
validator.effective_balance div MIN_SLASHING_PENALTY_QUOTIENT)
decrease_balance(state, index.ValidatorIndex, penalty)
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#final-updates
func process_final_updates(state: var BeaconState) =
let
current_epoch = get_current_epoch(state)
next_epoch = current_epoch + 1
# Reset eth1 data votes
if (state.slot + 1) mod SLOTS_PER_ETH1_VOTING_PERIOD == 0:
state.eth1_data_votes = @[]
# Update effective balances with hysteresis
for index, validator in state.validator_registry:
let balance = state.balances[index]
const HALF_INCREMENT = EFFECTIVE_BALANCE_INCREMENT div 2
if balance < validator.effective_balance or
validator.effective_balance + 3'u64 * HALF_INCREMENT < balance:
state.validator_registry[index].effective_balance =
min(
balance - balance mod EFFECTIVE_BALANCE_INCREMENT,
MAX_EFFECTIVE_BALANCE)
# Update start shard
state.latest_start_shard =
(state.latest_start_shard + get_shard_delta(state, current_epoch)) mod
SHARD_COUNT
# Set total slashed balances
state.latest_slashed_balances[next_epoch mod LATEST_SLASHED_EXIT_LENGTH] = (
state.latest_slashed_balances[current_epoch mod LATEST_SLASHED_EXIT_LENGTH]
)
# Set randao mix
state.latest_randao_mixes[next_epoch mod LATEST_RANDAO_MIXES_LENGTH] =
get_randao_mix(state, current_epoch)
# Set historical root accumulator
if next_epoch mod (SLOTS_PER_HISTORICAL_ROOT div SLOTS_PER_EPOCH).uint64 == 0:
let historical_batch = HistoricalBatch(
block_roots: state.latest_block_roots,
state_roots: state.latest_state_roots,
)
state.historical_roots.add (hash_tree_root(historical_batch))
# Rotate current/previous epoch attestations
state.previous_epoch_attestations = state.current_epoch_attestations
state.current_epoch_attestations = @[]
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#per-epoch-processing
func processEpoch*(state: var BeaconState) =
if not (state.slot > GENESIS_SLOT and
(state.slot + 1) mod SLOTS_PER_EPOCH == 0):
return
var per_epoch_cache = get_empty_per_epoch_cache()
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#justification-and-finalization
process_justification_and_finalization(state, per_epoch_cache)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#crosslinks
process_crosslinks(state, per_epoch_cache)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#rewards-and-penalties-1
process_rewards_and_penalties(state, per_epoch_cache)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#registry-updates
# Don't rely on caching here.
process_registry_updates(state)
## Caching here for get_crosslink_committee(...) can break otherwise, since
## get_active_validator_indices(...) usually changes.
clear(per_epoch_cache.crosslink_committee_cache)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#slashings
process_slashings(state)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#final-updates
process_final_updates(state)

849
beacon_chain/state_transition.nim
View File

@ -33,384 +33,8 @@
import import
algorithm, collections/sets, chronicles, math, options, sequtils, sets, tables, algorithm, collections/sets, chronicles, math, options, sequtils, sets, tables,
./extras, ./ssz, ./beacon_node_types, ./extras, ./ssz, ./beacon_node_types,
./spec/[beaconstate, bitfield, crypto, datatypes, digest, helpers, validator] ./spec/[beaconstate, bitfield, crypto, datatypes, digest, helpers, validator],
./spec/[state_transition_block, state_transition_epoch]
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#block-header
proc processBlockHeader(
state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags,
stateCache: var StateCache): bool =
# Verify that the slots match
if not (blck.slot == state.slot):
notice "Block header: slot mismatch",
block_slot = humaneSlotNum(blck.slot),
state_slot = humaneSlotNum(state.slot)
return false
# Verify that the parent matches
if skipValidation notin flags and not (blck.parent_root ==
signing_root(state.latest_block_header)):
notice "Block header: previous block root mismatch",
latest_block_header = state.latest_block_header,
blck = shortLog(blck),
latest_block_header_root = shortLog(signing_root(state.latest_block_header))
return false
# Save current block as the new latest block
state.latest_block_header = BeaconBlockHeader(
slot: blck.slot,
parent_root: blck.parent_root,
body_root: hash_tree_root(blck.body),
)
# Verify proposer is not slashed
let proposer =
state.validator_registry[get_beacon_proposer_index(state, stateCache)]
if proposer.slashed:
notice "Block header: proposer slashed"
return false
# Verify proposer signature
if skipValidation notin flags and not bls_verify(
proposer.pubkey,
signing_root(blck).data,
blck.signature,
get_domain(state, DOMAIN_BEACON_PROPOSER)):
notice "Block header: invalid block header",
proposer_pubkey = proposer.pubkey,
block_root = shortLog(signing_root(blck)),
block_signature = blck.signature
return false
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#randao
proc processRandao(
state: var BeaconState, body: BeaconBlockBody, flags: UpdateFlags,
stateCache: var StateCache): bool =
let
proposer_index = get_beacon_proposer_index(state, stateCache)
proposer = addr state.validator_registry[proposer_index]
# Verify that the provided randao value is valid
if skipValidation notin flags:
if not bls_verify(
proposer.pubkey,
hash_tree_root(get_current_epoch(state).uint64).data,
body.randao_reveal,
get_domain(state, DOMAIN_RANDAO)):
notice "Randao mismatch", proposer_pubkey = proposer.pubkey,
message = get_current_epoch(state),
signature = body.randao_reveal,
slot = state.slot
return false
# Mix it in
let
mix = get_current_epoch(state) mod LATEST_RANDAO_MIXES_LENGTH
rr = eth2hash(body.randao_reveal.getBytes()).data
for i, b in state.latest_randao_mixes[mix].data:
state.latest_randao_mixes[mix].data[i] = b xor rr[i]
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#eth1-data
func processEth1Data(state: var BeaconState, body: BeaconBlockBody) =
state.eth1_data_votes.add body.eth1_data
if state.eth1_data_votes.count(body.eth1_data) * 2 >
SLOTS_PER_ETH1_VOTING_PERIOD:
state.latest_eth1_data = body.eth1_data
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#is_slashable_validator
func is_slashable_validator(validator: Validator, epoch: Epoch): bool =
# Check if ``validator`` is slashable.
(not validator.slashed) and
(validator.activation_epoch <= epoch) and
(epoch < validator.withdrawable_epoch)
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#proposer-slashings
proc processProposerSlashings(
state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags,
stateCache: var StateCache): bool =
if len(blck.body.proposer_slashings) > MAX_PROPOSER_SLASHINGS:
notice "PropSlash: too many!",
proposer_slashings = len(blck.body.proposer_slashings)
return false
for proposer_slashing in blck.body.proposer_slashings:
let proposer = state.validator_registry[proposer_slashing.proposer_index.int]
# Verify that the epoch is the same
if not (slot_to_epoch(proposer_slashing.header_1.slot) ==
slot_to_epoch(proposer_slashing.header_2.slot)):
notice "PropSlash: epoch mismatch"
return false
# But the headers are different
if not (proposer_slashing.header_1 != proposer_slashing.header_2):
notice "PropSlash: headers not different"
return false
# Check proposer is slashable
if not is_slashable_validator(proposer, get_current_epoch(state)):
notice "PropSlash: slashed proposer"
return false
# Signatures are valid
if skipValidation notin flags:
for i, header in @[proposer_slashing.header_1, proposer_slashing.header_2]:
if not bls_verify(
proposer.pubkey,
signing_root(header).data,
header.signature,
get_domain(
state, DOMAIN_BEACON_PROPOSER, slot_to_epoch(header.slot))):
notice "PropSlash: invalid signature",
signature_index = i
return false
slashValidator(
state, proposer_slashing.proposer_index.ValidatorIndex, stateCache)
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#is_slashable_attestation_data
func is_slashable_attestation_data(
data_1: AttestationData, data_2: AttestationData): bool =
## Check if ``data_1`` and ``data_2`` are slashable according to Casper FFG
## rules.
# Double vote
(data_1 != data_2 and data_1.target_epoch == data_2.target_epoch) or
# Surround vote
(data_1.source_epoch < data_2.source_epoch and
data_2.target_epoch < data_1.target_epoch)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#attester-slashings
proc processAttesterSlashings(state: var BeaconState, blck: BeaconBlock,
stateCache: var StateCache): bool =
# Process ``AttesterSlashing`` operation.
if len(blck.body.attester_slashings) > MAX_ATTESTER_SLASHINGS:
notice "CaspSlash: too many!"
return false
result = true
for attester_slashing in blck.body.attester_slashings:
let
attestation_1 = attester_slashing.attestation_1
attestation_2 = attester_slashing.attestation_2
if not is_slashable_attestation_data(
attestation_1.data, attestation_2.data):
notice "CaspSlash: surround or double vote check failed"
return false
if not validate_indexed_attestation(state, attestation_1):
notice "CaspSlash: invalid votes 1"
return false
if not validate_indexed_attestation(state, attestation_2):
notice "CaspSlash: invalid votes 2"
return false
var slashed_any = false
## TODO there's a lot of sorting/set construction here and
## verify_indexed_attestation, but go by spec unless there
## is compelling perf evidence otherwise.
let attesting_indices_1 =
attestation_1.custody_bit_0_indices & attestation_1.custody_bit_1_indices
let attesting_indices_2 =
attestation_2.custody_bit_0_indices & attestation_2.custody_bit_1_indices
for index in sorted(toSeq(intersection(toSet(attesting_indices_1),
toSet(attesting_indices_2)).items), system.cmp):
if is_slashable_validator(state.validator_registry[index.int],
get_current_epoch(state)):
slash_validator(state, index.ValidatorIndex, stateCache)
slashed_any = true
result = result and slashed_any
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#attestations
proc processAttestations(
state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags,
stateCache: var StateCache): bool =
## Each block includes a number of attestations that the proposer chose. Each
## attestation represents an update to a specific shard and is signed by a
## committee of validators.
## Here we make sanity checks for each attestation and it to the state - most
## updates will happen at the epoch boundary where state updates happen in
## bulk.
if blck.body.attestations.len > MAX_ATTESTATIONS:
notice "Attestation: too many!", attestations = blck.body.attestations.len
return false
if not blck.body.attestations.allIt(checkAttestation(state, it, flags, stateCache)):
return false
# All checks passed - update state
# Apply the attestations
var committee_count_cache = initTable[Epoch, uint64]()
for attestation in blck.body.attestations:
# Caching
let
epoch = attestation.data.target_epoch
committee_count = if epoch in committee_count_cache:
committee_count_cache[epoch]
else:
get_epoch_committee_count(state, epoch)
committee_count_cache[epoch] = committee_count
# Spec content
let attestation_slot =
get_attestation_data_slot(state, attestation.data, committee_count)
let pending_attestation = PendingAttestation(
data: attestation.data,
aggregation_bitfield: attestation.aggregation_bitfield,
inclusion_delay: state.slot - attestation_slot,
proposer_index: get_beacon_proposer_index(state, stateCache),
)
if attestation.data.target_epoch == get_current_epoch(state):
state.current_epoch_attestations.add(pending_attestation)
else:
state.previous_epoch_attestations.add(pending_attestation)
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.5.1/specs/core/0_beacon-chain.md#deposits
proc processDeposits(state: var BeaconState, blck: BeaconBlock): bool =
if not (len(blck.body.deposits) <= MAX_DEPOSITS):
notice "processDeposits: too many deposits"
return false
for deposit in blck.body.deposits:
if not process_deposit(state, deposit):
notice "processDeposits: deposit invalid"
return false
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#voluntary-exits
proc processVoluntaryExits(
state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags): bool =
# Process ``VoluntaryExit`` transaction.
if len(blck.body.voluntary_exits) > MAX_VOLUNTARY_EXITS:
notice "Exit: too many!"
return false
for exit in blck.body.voluntary_exits:
let validator = state.validator_registry[exit.validator_index.int]
# Verify the validator is active
if not is_active_validator(validator, get_current_epoch(state)):
notice "Exit: validator not active"
return false
# Verify the validator has not yet exited
if not (validator.exit_epoch == FAR_FUTURE_EPOCH):
notice "Exit: validator has exited"
return false
## Exits must specify an epoch when they become valid; they are not valid
## before then
if not (get_current_epoch(state) >= exit.epoch):
notice "Exit: exit epoch not passed"
return false
# Verify the validator has been active long enough
# TODO detect underflow
if not (get_current_epoch(state) - validator.activation_epoch >=
PERSISTENT_COMMITTEE_PERIOD):
notice "Exit: not in validator set long enough"
return false
# Verify signature
if skipValidation notin flags:
if not bls_verify(
validator.pubkey, signing_root(exit).data, exit.signature,
get_domain(state, DOMAIN_VOLUNTARY_EXIT, exit.epoch)):
notice "Exit: invalid signature"
return false
# Initiate exit
initiate_validator_exit(state, exit.validator_index.ValidatorIndex)
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#transfers
proc processTransfers(state: var BeaconState, blck: BeaconBlock,
flags: UpdateFlags, stateCache: var StateCache): bool =
if not (len(blck.body.transfers) <= MAX_TRANSFERS):
notice "Transfer: too many transfers"
return false
for transfer in blck.body.transfers:
let sender_balance = state.balances[transfer.sender.int]
## Verify the amount and fee are not individually too big (for anti-overflow
## purposes)
if not (sender_balance >= max(transfer.amount, transfer.fee)):
notice "Transfer: sender balance too low for transfer amount or fee"
return false
# A transfer is valid in only one slot
if not (state.slot == transfer.slot):
notice "Transfer: slot mismatch"
return false
## Sender must be not yet eligible for activation, withdrawn, or transfer
## balance over MAX_EFFECTIVE_BALANCE
if not (
state.validator_registry[transfer.sender.int].activation_epoch ==
FAR_FUTURE_EPOCH or
get_current_epoch(state) >=
state.validator_registry[
transfer.sender.int].withdrawable_epoch or
transfer.amount + transfer.fee + MAX_EFFECTIVE_BALANCE <=
state.balances[transfer.sender.int]):
notice "Transfer: only withdrawn or not-activated accounts with sufficient balance can transfer"
return false
# Verify that the pubkey is valid
let wc = state.validator_registry[transfer.sender.int].
withdrawal_credentials
if not (wc.data[0] == BLS_WITHDRAWAL_PREFIX and
wc.data[1..^1] == eth2hash(transfer.pubkey.getBytes).data[1..^1]):
notice "Transfer: incorrect withdrawal credentials"
return false
# Verify that the signature is valid
if skipValidation notin flags:
if not bls_verify(
transfer.pubkey, signing_root(transfer).data, transfer.signature,
get_domain(state, DOMAIN_TRANSFER)):
notice "Transfer: incorrect signature"
return false
# Process the transfer
decrease_balance(
state, transfer.sender.ValidatorIndex, transfer.amount + transfer.fee)
increase_balance(
state, transfer.recipient.ValidatorIndex, transfer.amount)
increase_balance(
state, get_beacon_proposer_index(state, stateCache), transfer.fee)
# Verify balances are not dust
if not (
0'u64 < state.balances[transfer.sender.int] and
state.balances[transfer.sender.int] < MIN_DEPOSIT_AMOUNT):
notice "Transfer: sender balance too low for transfer amount or fee"
return false
if not (
0'u64 < state.balances[transfer.recipient.int] and
state.balances[transfer.recipient.int] < MIN_DEPOSIT_AMOUNT):
notice "Transfer: sender balance too low for transfer amount or fee"
return false
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#per-slot-processing # https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#per-slot-processing
func advance_slot(state: var BeaconState) = func advance_slot(state: var BeaconState) =
@ -436,475 +60,6 @@ func process_slot(state: var BeaconState) =
state.latest_block_roots[state.slot mod SLOTS_PER_HISTORICAL_ROOT] = state.latest_block_roots[state.slot mod SLOTS_PER_HISTORICAL_ROOT] =
signing_root(state.latest_block_header) signing_root(state.latest_block_header)
proc processBlock(
state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags,
stateCache: var StateCache): bool =
## When there's a new block, we need to verify that the block is sane and
## update the state accordingly
# TODO when there's a failure, we should reset the state!
# TODO probably better to do all verification first, then apply state changes
if not processBlockHeader(state, blck, flags, stateCache):
notice "Block header not valid", slot = humaneSlotNum(state.slot)
return false
if not processRandao(state, blck.body, flags, stateCache):
debug "[Block processing] Randao failure", slot = humaneSlotNum(state.slot)
return false
processEth1Data(state, blck.body)
if not processProposerSlashings(state, blck, flags, stateCache):
debug "[Block processing] Proposer slashing failure", slot = humaneSlotNum(state.slot)
return false
if not processAttesterSlashings(state, blck, stateCache):
debug "[Block processing] Attester slashing failure", slot = humaneSlotNum(state.slot)
return false
if not processAttestations(state, blck, flags, stateCache):
debug "[Block processing] Attestation processing failure", slot = humaneSlotNum(state.slot)
return false
if not processDeposits(state, blck):
debug "[Block processing] Deposit processing failure", slot = humaneSlotNum(state.slot)
return false
if not processVoluntaryExits(state, blck, flags):
debug "[Block processing] Exit processing failure", slot = humaneSlotNum(state.slot)
return false
if not processTransfers(state, blck, flags, stateCache):
debug "[Block processing] Transfer processing failure", slot = humaneSlotNum(state.slot)
return false
true
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#helper-functions-1
func get_total_active_balance(state: BeaconState): Gwei =
return get_total_balance(
state,
get_active_validator_indices(state, get_current_epoch(state)))
func get_matching_source_attestations(state: BeaconState, epoch: Epoch):
seq[PendingAttestation] =
doAssert epoch in @[get_current_epoch(state), get_previous_epoch(state)]
if epoch == get_current_epoch(state):
state.current_epoch_attestations
else:
state.previous_epoch_attestations
func get_matching_target_attestations(state: BeaconState, epoch: Epoch):
seq[PendingAttestation] =
filterIt(
get_matching_source_attestations(state, epoch),
it.data.target_root == get_block_root(state, epoch)
)
func get_matching_head_attestations(state: BeaconState, epoch: Epoch):
seq[PendingAttestation] =
filterIt(
get_matching_source_attestations(state, epoch),
it.data.beacon_block_root ==
get_block_root_at_slot(state, get_attestation_data_slot(state, it.data))
)
func get_unslashed_attesting_indices(
state: BeaconState, attestations: seq[PendingAttestation],
stateCache: var StateCache): HashSet[ValidatorIndex] =
result = initSet[ValidatorIndex]()
for a in attestations:
result = result.union(get_attesting_indices(
state, a.data, a.aggregation_bitfield, stateCache))
for index in result:
if state.validator_registry[index].slashed:
result.excl index
func get_attesting_balance(
state: BeaconState, attestations: seq[PendingAttestation],
stateCache: var StateCache): Gwei =
get_total_balance(state, get_unslashed_attesting_indices(
state, attestations, stateCache))
# Not exactly in spec, but for get_winning_crosslink_and_attesting_indices
func lowerThan(candidate, current: Eth2Digest): bool =
# return true iff candidate is "lower" than current, per spec rule:
# "ties broken in favor of lexicographically higher hash
for i, v in current.data:
if v > candidate.data[i]: return true
false
func get_winning_crosslink_and_attesting_indices(
state: BeaconState, epoch: Epoch, shard: Shard,
stateCache: var StateCache): tuple[a: Crosslink, b: HashSet[ValidatorIndex]] =
let
attestations =
filterIt(
get_matching_source_attestations(state, epoch),
it.data.crosslink.shard == shard)
# TODO don't keep h_t_r'ing state.current_crosslinks[shard]
crosslinks =
filterIt(
mapIt(attestations, it.data.crosslink),
hash_tree_root(state.current_crosslinks[shard]) in
# TODO pointless memory allocation, etc.
@[it.parent_root, hash_tree_root(it)])
# default=Crosslink()
if len(crosslinks) == 0:
return (Crosslink(), initSet[ValidatorIndex]())
## Winning crosslink has the crosslink data root with the most balance voting
## for it (ties broken lexicographically)
var
winning_crosslink: Crosslink
winning_crosslink_balance = 0.Gwei
for candidate_crosslink in crosslinks:
## TODO check if should cache this again
## let root_balance = get_attesting_balance_cached(
## state, attestations_for.getOrDefault(r), cache)
let crosslink_balance =
get_attesting_balance(
state,
filterIt(attestations, it.data.crosslink == candidate_crosslink),
stateCache)
if (crosslink_balance > winning_crosslink_balance or
(winning_crosslink_balance == crosslink_balance and
lowerThan(winning_crosslink.data_root,
candidate_crosslink.data_root))):
winning_crosslink = candidate_crosslink
winning_crosslink_balance = crosslink_balance
let winning_attestations =
filterIt(attestations, it.data.crosslink == winning_crosslink)
(winning_crosslink,
get_unslashed_attesting_indices(state, winning_attestations, stateCache))
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#justification-and-finalization
func process_justification_and_finalization(
state: var BeaconState, stateCache: var StateCache) =
if get_current_epoch(state) <= GENESIS_EPOCH + 1:
return
let
previous_epoch = get_previous_epoch(state)
current_epoch = get_current_epoch(state)
old_previous_justified_epoch = state.previous_justified_epoch
old_current_justified_epoch = state.current_justified_epoch
# Process justifications
state.previous_justified_epoch = state.current_justified_epoch
state.previous_justified_root = state.current_justified_root
state.justification_bitfield = (state.justification_bitfield shl 1)
let previous_epoch_matching_target_balance =
get_attesting_balance(state,
get_matching_target_attestations(state, previous_epoch), stateCache)
if previous_epoch_matching_target_balance * 3 >=
get_total_active_balance(state) * 2:
state.current_justified_epoch = previous_epoch
state.current_justified_root =
get_block_root(state, state.current_justified_epoch)
state.justification_bitfield = state.justification_bitfield or (1 shl 1)
let current_epoch_matching_target_balance =
get_attesting_balance(state,
get_matching_target_attestations(state, current_epoch),
stateCache)
if current_epoch_matching_target_balance * 3 >=
get_total_active_balance(state) * 2:
state.current_justified_epoch = current_epoch
state.current_justified_root =
get_block_root(state, state.current_justified_epoch)
state.justification_bitfield = state.justification_bitfield or (1 shl 0)
# Process finalizations
let bitfield = state.justification_bitfield
## The 2nd/3rd/4th most recent epochs are justified, the 2nd using the 4th
## as source
if (bitfield shr 1) mod 8 == 0b111 and old_previous_justified_epoch + 3 ==
current_epoch:
state.finalized_epoch = old_previous_justified_epoch
state.finalized_root = get_block_root(state, state.finalized_epoch)
## The 2nd/3rd most recent epochs are justified, the 2nd using the 3rd as
## source
if (bitfield shr 1) mod 4 == 0b11 and old_previous_justified_epoch + 2 ==
current_epoch:
state.finalized_epoch = old_previous_justified_epoch
state.finalized_root = get_block_root(state, state.finalized_epoch)
## The 1st/2nd/3rd most recent epochs are justified, the 1st using the 3rd as
## source
if (bitfield shr 0) mod 8 == 0b111 and old_current_justified_epoch + 2 ==
current_epoch:
state.finalized_epoch = old_current_justified_epoch
state.finalized_root = get_block_root(state, state.finalized_epoch)
## The 1st/2nd most recent epochs are justified, the 1st using the 2nd as
## source
if (bitfield shr 0) mod 4 == 0b11 and old_current_justified_epoch + 1 ==
current_epoch:
state.finalized_epoch = old_current_justified_epoch
state.finalized_root = get_block_root(state, state.finalized_epoch)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#crosslinks
func process_crosslinks(state: var BeaconState, stateCache: var StateCache) =
## TODO is there a semantic reason for this, or is this just a way to force
## copying? If so, why not just `list(foo)` or similar? This is strange. In
## this case, for type reasons, don't do weird
## [c for c in state.current_crosslinks] from spec.
state.previous_crosslinks = state.current_crosslinks
for epoch_int in get_previous_epoch(state).uint64 ..
get_current_epoch(state).uint64:
# This issue comes up regularly -- iterating means an int type,
# which then needs re-conversion back to specialized type.
let epoch = epoch_int.Epoch
for offset in 0'u64 ..< get_epoch_committee_count(state, epoch):
let
shard = (get_epoch_start_shard(state, epoch) + offset) mod SHARD_COUNT
crosslink_committee =
get_crosslink_committee(state, epoch, shard, stateCache)
# In general, it'll loop over the same shards twice, and
# get_winning_root_and_participants is defined to return
# the same results from the previous epoch as current.
# TODO cache like before, in 0.5 version of this function
(winning_crosslink, attesting_indices) =
get_winning_crosslink_and_attesting_indices(
state, epoch, shard, stateCache)
if 3'u64 * get_total_balance(state, attesting_indices) >=
2'u64 * get_total_balance(state, crosslink_committee):
state.current_crosslinks[shard] = winning_crosslink
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#rewards-and-penalties-1
func get_base_reward(state: BeaconState, index: ValidatorIndex): Gwei =
let
total_balance = get_total_active_balance(state)
effective_balance = state.validator_registry[index].effective_balance
effective_balance * BASE_REWARD_FACTOR div
integer_squareroot(total_balance) div BASE_REWARDS_PER_EPOCH
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#rewards-and-penalties
func get_attestation_deltas(state: BeaconState, stateCache: var StateCache):
tuple[a: seq[Gwei], b: seq[Gwei]] =
let
previous_epoch = get_previous_epoch(state)
total_balance = get_total_active_balance(state)
var
rewards = repeat(0'u64, len(state.validator_registry))
penalties = repeat(0'u64, len(state.validator_registry))
eligible_validator_indices : seq[ValidatorIndex] = @[]
for index, v in state.validator_registry:
if is_active_validator(v, previous_epoch) or
(v.slashed and previous_epoch + 1 < v.withdrawable_epoch):
eligible_validator_indices.add index.ValidatorIndex
# Micro-incentives for matching FFG source, FFG target, and head
let
matching_source_attestations =
get_matching_source_attestations(state, previous_epoch)
matching_target_attestations =
get_matching_target_attestations(state, previous_epoch)
matching_head_attestations =
get_matching_head_attestations(state, previous_epoch)
for attestations in
@[matching_source_attestations, matching_target_attestations,
matching_head_attestations]:
let
unslashed_attesting_indices =
get_unslashed_attesting_indices(state, attestations, stateCache)
attesting_balance = get_attesting_balance(state, attestations, stateCache)
for index in eligible_validator_indices:
if index in unslashed_attesting_indices:
rewards[index] +=
get_base_reward(state, index) * attesting_balance div total_balance
else:
penalties[index] += get_base_reward(state, index)
if matching_source_attestations.len == 0:
return (rewards, penalties)
# Proposer and inclusion delay micro-rewards
for index in get_unslashed_attesting_indices(
state, matching_source_attestations, stateCache):
doAssert matching_source_attestations.len > 0
var attestation = matching_source_attestations[0]
for a in matching_source_attestations:
if index notin get_attesting_indices(
state, a.data, a.aggregation_bitfield, stateCache):
continue
if a.inclusion_delay < attestation.inclusion_delay:
attestation = a
rewards[attestation.proposer_index] += get_base_reward(state, index) div
PROPOSER_REWARD_QUOTIENT
rewards[index] +=
get_base_reward(state, index) * MIN_ATTESTATION_INCLUSION_DELAY div
attestation.inclusion_delay
# Inactivity penalty
let finality_delay = previous_epoch - state.finalized_epoch
if finality_delay > MIN_EPOCHS_TO_INACTIVITY_PENALTY:
let matching_target_attesting_indices =
get_unslashed_attesting_indices(
state, matching_target_attestations, stateCache)
for index in eligible_validator_indices:
penalties[index] +=
BASE_REWARDS_PER_EPOCH.uint64 * get_base_reward(state, index)
if index notin matching_target_attesting_indices:
penalties[index] +=
state.validator_registry[index].effective_balance *
finality_delay div INACTIVITY_PENALTY_QUOTIENT
(rewards, penalties)
# TODO re-cache this one, as under 0.5 version, if profiling suggests it
func get_crosslink_deltas(state: BeaconState, cache: var StateCache):
tuple[a: seq[Gwei], b: seq[Gwei]] =
var
rewards = repeat(0'u64, len(state.validator_registry))
penalties = repeat(0'u64, len(state.validator_registry))
let epoch = get_previous_epoch(state)
for offset in 0'u64 ..< get_epoch_committee_count(state, epoch):
let
shard = (get_epoch_start_shard(state, epoch) + offset) mod SHARD_COUNT
crosslink_committee =
get_crosslink_committee(state, epoch, shard, cache)
(winning_crosslink, attesting_indices) =
get_winning_crosslink_and_attesting_indices(
state, epoch, shard, cache)
attesting_balance = get_total_balance(state, attesting_indices)
committee_balance = get_total_balance(state, crosslink_committee)
for index in crosslink_committee:
let base_reward = get_base_reward(state, index)
if index in attesting_indices:
rewards[index] +=
get_base_reward(state, index) * attesting_balance div
committee_balance
else:
penalties[index] += get_base_reward(state, index)
(rewards, penalties)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#rewards-and-penalties-1
func process_rewards_and_penalties(
state: var BeaconState, cache: var StateCache) =
if get_current_epoch(state) == GENESIS_EPOCH:
return
let
(rewards1, penalties1) = get_attestation_deltas(state, cache)
(rewards2, penalties2) = get_crosslink_deltas(state, cache)
for i in 0 ..< len(state.validator_registry):
increase_balance(state, i.ValidatorIndex, rewards1[i] + rewards2[i])
decrease_balance(state, i.ValidatorIndex, penalties1[i] + penalties2[i])
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#slashings
func process_slashings(state: var BeaconState) =
let
current_epoch = get_current_epoch(state)
total_balance = get_total_active_balance(state)
# Compute `total_penalties`
total_at_start = state.latest_slashed_balances[
(current_epoch + 1) mod LATEST_SLASHED_EXIT_LENGTH]
total_at_end =
state.latest_slashed_balances[current_epoch mod
LATEST_SLASHED_EXIT_LENGTH]
total_penalties = total_at_end - total_at_start
for index, validator in state.validator_registry:
if validator.slashed and current_epoch == validator.withdrawable_epoch -
LATEST_SLASHED_EXIT_LENGTH div 2:
let
penalty = max(
validator.effective_balance *
min(total_penalties * 3, total_balance) div total_balance,
validator.effective_balance div MIN_SLASHING_PENALTY_QUOTIENT)
decrease_balance(state, index.ValidatorIndex, penalty)
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#final-updates
func process_final_updates(state: var BeaconState) =
let
current_epoch = get_current_epoch(state)
next_epoch = current_epoch + 1
# Reset eth1 data votes
if (state.slot + 1) mod SLOTS_PER_ETH1_VOTING_PERIOD == 0:
state.eth1_data_votes = @[]
# Update effective balances with hysteresis
for index, validator in state.validator_registry:
let balance = state.balances[index]
const HALF_INCREMENT = EFFECTIVE_BALANCE_INCREMENT div 2
if balance < validator.effective_balance or
validator.effective_balance + 3'u64 * HALF_INCREMENT < balance:
state.validator_registry[index].effective_balance =
min(
balance - balance mod EFFECTIVE_BALANCE_INCREMENT,
MAX_EFFECTIVE_BALANCE)
# Update start shard
state.latest_start_shard =
(state.latest_start_shard + get_shard_delta(state, current_epoch)) mod
SHARD_COUNT
# Set total slashed balances
state.latest_slashed_balances[next_epoch mod LATEST_SLASHED_EXIT_LENGTH] = (
state.latest_slashed_balances[current_epoch mod LATEST_SLASHED_EXIT_LENGTH]
)
# Set randao mix
state.latest_randao_mixes[next_epoch mod LATEST_RANDAO_MIXES_LENGTH] =
get_randao_mix(state, current_epoch)
# Set historical root accumulator
if next_epoch mod (SLOTS_PER_HISTORICAL_ROOT div SLOTS_PER_EPOCH).uint64 == 0:
let historical_batch = HistoricalBatch(
block_roots: state.latest_block_roots,
state_roots: state.latest_state_roots,
)
state.historical_roots.add (hash_tree_root(historical_batch))
# Rotate current/previous epoch attestations
state.previous_epoch_attestations = state.current_epoch_attestations
state.current_epoch_attestations = @[]
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#per-epoch-processing
func processEpoch(state: var BeaconState) =
if not (state.slot > GENESIS_SLOT and
(state.slot + 1) mod SLOTS_PER_EPOCH == 0):
return
var per_epoch_cache = get_empty_per_epoch_cache()
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#justification-and-finalization
process_justification_and_finalization(state, per_epoch_cache)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#crosslinks
process_crosslinks(state, per_epoch_cache)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#rewards-and-penalties-1
process_rewards_and_penalties(state, per_epoch_cache)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#registry-updates
# Don't rely on caching here.
process_registry_updates(state)
## Caching here for get_crosslink_committee(...) can break otherwise, since
## get_active_validator_indices(...) usually changes.
clear(per_epoch_cache.crosslink_committee_cache)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#slashings
process_slashings(state)
# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#final-updates
process_final_updates(state)
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#state-root-verification # https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#state-root-verification
proc verifyStateRoot(state: BeaconState, blck: BeaconBlock): bool = proc verifyStateRoot(state: BeaconState, blck: BeaconBlock): bool =
let state_root = hash_tree_root(state) let state_root = hash_tree_root(state)