nimbus-eth2/beacon_chain/exit_pool.nim

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# beacon_chain
# Copyright (c) 2020 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
# Standard libraries
std/[deques, options, sequtils, sets, tables],
# Status libraries
chronicles, json_serialization/std/sets as jsonSets,
# Internal
./spec/[crypto, datatypes, helpers, state_transition_block],
./block_pools/[chain_dag, clearance, quarantine],
./beacon_node_types
export beacon_node_types, sets
logScope: topics = "exitpool"
const
ATTESTER_SLASHINGS_BOUND = MAX_ATTESTER_SLASHINGS * 2
PROPOSER_SLASHINGS_BOUND = MAX_PROPOSER_SLASHINGS * 2
VOLUNTARY_EXITS_BOUND = MAX_VOLUNTARY_EXITS * 2
proc init*(
T: type ExitPool, chainDag: ChainDAGRef, quarantine: QuarantineRef): T =
## Initialize an ExitPool from the chainDag `headState`
T(
# Allow for filtering out some exit messages during block production
attester_slashings:
initDeque[AttesterSlashing](initialSize = ATTESTER_SLASHINGS_BOUND.int),
proposer_slashings:
initDeque[ProposerSlashing](initialSize = PROPOSER_SLASHINGS_BOUND.int),
voluntary_exits:
initDeque[SignedVoluntaryExit](initialSize = VOLUNTARY_EXITS_BOUND.int),
chainDag: chainDag,
quarantine: quarantine
)
func addExitMessage*(subpool: var auto, exitMessage, bound: auto) =
# Prefer newer to older exit messages
while subpool.lenu64 >= bound:
discard subpool.popFirst()
subpool.addLast(exitMessage)
doAssert subpool.lenu64 <= bound
iterator getValidatorIndices(attester_slashing: AttesterSlashing): uint64 =
# TODO rely on sortedness and do this sans memory allocations, but it's only
# when producing a beacon block, which is rare bottlenecked elsewhere.
let
attestation_1_indices =
attester_slashing.attestation_1.attesting_indices.asSeq
attestation_2_indices =
attester_slashing.attestation_2.attesting_indices.asSeq
attester_slashed_indices =
toHashSet(attestation_1_indices) * toHashSet(attestation_2_indices)
for validator_index in attester_slashed_indices:
yield validator_index
iterator getValidatorIndices(proposer_slashing: ProposerSlashing): uint64 =
yield proposer_slashing.signed_header_1.message.proposer_index
iterator getValidatorIndices(voluntary_exit: SignedVoluntaryExit): uint64 =
yield voluntary_exit.message.validator_index
# TODO stew/sequtils2
template allIt(s, pred: untyped): bool =
# https://github.com/nim-lang/Nim/blob/version-1-2/lib/pure/collections/sequtils.nim#L640-L662
# without the items(...)
var result = true
for it {.inject.} in s:
if not pred:
result = false
break
result
func getExitMessagesForBlock[T](
subpool: var Deque[T], pool: var ExitPool, bound: uint64): seq[T] =
# Approach taken here is to simply collect messages, effectively, a circular
# buffer and only re-validate that they haven't already found themselves out
# of the network eventually via some exit message at block construction time
# at which point we use exit_epoch. It doesn't matter which of these message
# types has triggered that exit, as the validation on incoming messages will
# find it to either be IGNORE (if it's the same type of exit message) or, if
# it's a different type, REJECT. Neither is worth packaging into BeaconBlock
# messages we broadcast.
#
# Beyond that, no other criterion of the exit messages' validity changes from
# when they were created, so given that we validated them to start with, they
# otherwise remain as valid as when we received them. There's no need to thus
# re-validate them on their way out.
#
# This overall approach handles a scenario wherein we receive an exit message
# over gossip and put it in the pool; receive a block X, with that message in
# it, and select it as head; then orphan block X and build instead on X-1. If
# this occurs, only validating after the fact ensures that we still broadcast
# out those exit messages that were in orphaned block X by not having eagerly
# removed them, if we have the chance.
while true:
if subpool.len == 0 or result.lenu64 >= bound:
break
# Prefer recent messages
let exit_message = subpool.popLast()
if allIt(
getValidatorIndices(exit_message),
pool.chainDag.headState.data.data.validators[it].exit_epoch !=
FAR_FUTURE_EPOCH):
# A beacon block exit message already targeted all these validators
continue
result.add exit_message
subpool.clear()
doAssert result.lenu64 <= bound
func getAttesterSlashingsForBlock*(pool: var ExitPool):
seq[AttesterSlashing] =
## Retrieve attester slashings that may be added to a new block
getExitMessagesForBlock[AttesterSlashing](
pool.attester_slashings, pool, MAX_ATTESTER_SLASHINGS)
func getProposerSlashingsForBlock*(pool: var ExitPool):
seq[ProposerSlashing] =
## Retrieve proposer slashings that may be added to a new block
getExitMessagesForBlock[ProposerSlashing](
pool.proposer_slashings, pool, MAX_PROPOSER_SLASHINGS)
func getVoluntaryExitsForBlock*(pool: var ExitPool):
seq[SignedVoluntaryExit] =
## Retrieve voluntary exits that may be added to a new block
getExitMessagesForBlock[SignedVoluntaryExit](
pool.voluntary_exits, pool, MAX_VOLUNTARY_EXITS)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0/specs/phase0/p2p-interface.md#attester_slashing
proc validateAttesterSlashing*(
pool: var ExitPool, attester_slashing: AttesterSlashing):
Result[bool, (ValidationResult, cstring)] =
# [IGNORE] At least one index in the intersection of the attesting indices of
# each attestation has not yet been seen in any prior attester_slashing (i.e.
# attester_slashed_indices = set(attestation_1.attesting_indices).intersection(attestation_2.attesting_indices),
# verify if any(attester_slashed_indices.difference(prior_seen_attester_slashed_indices))).
# TODO sequtils2 should be able to make this more reasonable, from asSeq on
# down, and can sort and just find intersection that way
let
attestation_1_indices =
attester_slashing.attestation_1.attesting_indices.asSeq
attestation_2_indices =
attester_slashing.attestation_2.attesting_indices.asSeq
attester_slashed_indices =
toHashSet(attestation_1_indices) * toHashSet(attestation_2_indices)
if not disjoint(
attester_slashed_indices, pool.prior_seen_attester_slashed_indices):
return err((ValidationResult.Ignore, cstring(
"validateAttesterSlashing: attester-slashed index already attester-slashed")))
# [REJECT] All of the conditions within process_attester_slashing pass
# validation.
var cache =
getStateCache(pool.chainDag.head,
pool.chainDag.headState.data.data.slot.compute_epoch_at_slot)
let attester_slashing_validity =
check_attester_slashing(
pool.chainDag.headState.data.data, attester_slashing, {}, cache)
if attester_slashing_validity.isErr:
return err((ValidationResult.Reject, attester_slashing_validity.error))
pool.prior_seen_attester_slashed_indices.incl attester_slashed_indices
pool.attester_slashings.addExitMessage(
attester_slashing, ATTESTER_SLASHINGS_BOUND)
ok(true)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0/specs/phase0/p2p-interface.md#proposer_slashing
proc validateProposerSlashing*(
pool: var ExitPool, proposer_slashing: ProposerSlashing):
Result[bool, (ValidationResult, cstring)] =
# [IGNORE] The proposer slashing is the first valid proposer slashing
# received for the proposer with index
# proposer_slashing.signed_header_1.message.proposer_index.
if proposer_slashing.signed_header_1.message.proposer_index in
pool.prior_seen_proposer_slashed_indices:
return err((ValidationResult.Ignore, cstring(
"validateProposerSlashing: proposer-slashed index already proposer-slashed")))
# [REJECT] All of the conditions within process_proposer_slashing pass validation.
var cache =
getStateCache(pool.chainDag.head,
pool.chainDag.headState.data.data.slot.compute_epoch_at_slot)
let proposer_slashing_validity =
check_proposer_slashing(
pool.chainDag.headState.data.data, proposer_slashing, {}, cache)
if proposer_slashing_validity.isErr:
return err((ValidationResult.Reject, proposer_slashing_validity.error))
pool.prior_seen_proposer_slashed_indices.incl(
proposer_slashing.signed_header_1.message.proposer_index)
pool.proposer_slashings.addExitMessage(
proposer_slashing, PROPOSER_SLASHINGS_BOUND)
ok(true)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0/specs/phase0/p2p-interface.md#voluntary_exit
proc validateVoluntaryExit*(
pool: var ExitPool, signed_voluntary_exit: SignedVoluntaryExit):
Result[void, (ValidationResult, cstring)] =
# [IGNORE] The voluntary exit is the first valid voluntary exit received for
# the validator with index signed_voluntary_exit.message.validator_index.
if signed_voluntary_exit.message.validator_index >=
pool.chainDag.headState.data.data.validators.lenu64:
return err((ValidationResult.Ignore, cstring(
"validateVoluntaryExit: validator index too high")))
if signed_voluntary_exit.message.validator_index in
pool.prior_seen_voluntary_exit_indices:
return err((ValidationResult.Ignore, cstring(
"validateVoluntaryExit: validator index already voluntarily exited")))
# [REJECT] All of the conditions within process_voluntary_exit pass
# validation.
var cache =
getStateCache(pool.chainDag.head,
pool.chainDag.headState.data.data.slot.compute_epoch_at_slot)
let voluntary_exit_validity =
check_voluntary_exit(
pool.chainDag.headState.data.data, signed_voluntary_exit, {}, cache)
if voluntary_exit_validity.isErr:
return err((ValidationResult.Reject, voluntary_exit_validity.error))
pool.prior_seen_voluntary_exit_indices.incl(
signed_voluntary_exit.message.validator_index)
pool.voluntary_exits.addExitMessage(
signed_voluntary_exit, VOLUNTARY_EXITS_BOUND)
ok()