nimbus-eth2/beacon_chain/validator_duties.nim

487 lines
20 KiB
Nim

# beacon_chain
# Copyright (c) 2018-2020 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.
import
# Standard library
os, tables, strutils,
# Nimble packages
stew/[byteutils, objects], stew/shims/macros,
chronos, metrics, json_rpc/[rpcserver, jsonmarshal],
chronicles,
json_serialization/std/[options, sets, net], serialization/errors,
eth/db/kvstore,
eth/[keys, async_utils], eth/p2p/discoveryv5/[protocol, enr],
# Local modules
spec/[datatypes, digest, crypto, beaconstate, helpers, validator, network],
conf, time, validator_pool, state_transition,
attestation_pool, block_pool, eth2_network, keystore_management,
beacon_node_common, beacon_node_types, nimbus_binary_common,
mainchain_monitor, version, ssz/merkleization, interop,
attestation_aggregation, sync_manager, sszdump
# Metrics for tracking attestation and beacon block loss
declareCounter beacon_attestations_sent,
"Number of beacon chain attestations sent by this peer"
declareCounter beacon_blocks_proposed,
"Number of beacon chain blocks sent by this peer"
logScope: topics = "beacval"
proc saveValidatorKey*(keyName, key: string, conf: BeaconNodeConf) =
let validatorsDir = conf.validatorsDir
let outputFile = validatorsDir / keyName
createDir validatorsDir
writeFile(outputFile, key)
info "Imported validator key", file = outputFile
proc addLocalValidator*(node: BeaconNode,
state: BeaconState,
privKey: ValidatorPrivKey) =
let pubKey = privKey.toPubKey()
let idx = state.validators.asSeq.findIt(it.pubKey == pubKey)
if idx == -1:
# We allow adding a validator even if its key is not in the state registry:
# it might be that the deposit for this validator has not yet been processed
warn "Validator not in registry (yet?)", pubKey
node.attachedValidators.addLocalValidator(pubKey, privKey)
proc addLocalValidators*(node: BeaconNode, state: BeaconState) =
for validatorKey in node.config.validatorKeys:
node.addLocalValidator state, validatorKey
info "Local validators attached ", count = node.attachedValidators.count
func getAttachedValidator*(node: BeaconNode,
state: BeaconState,
idx: ValidatorIndex): AttachedValidator =
let validatorKey = state.validators[idx].pubkey
node.attachedValidators.getValidator(validatorKey)
proc isSynced(node: BeaconNode, head: BlockRef): bool =
## TODO This function is here as a placeholder for some better heurestics to
## determine if we're in sync and should be producing blocks and
## attestations. Generally, the problem is that slot time keeps advancing
## even when there are no blocks being produced, so there's no way to
## distinguish validators geniunely going missing from the node not being
## well connected (during a network split or an internet outage for
## example). It would generally be correct to simply keep running as if
## we were the only legit node left alive, but then we run into issues:
## with enough many empty slots, the validator pool is emptied leading
## to empty committees and lots of empty slot processing that will be
## thrown away as soon as we're synced again.
let
# The slot we should be at, according to the clock
beaconTime = node.beaconClock.now()
wallSlot = beaconTime.toSlot()
# TODO if everyone follows this logic, the network will not recover from a
# halt: nobody will be producing blocks because everone expects someone
# else to do it
if wallSlot.afterGenesis and head.slot + MaxEmptySlotCount < wallSlot.slot:
false
else:
true
proc sendAttestation*(node: BeaconNode, attestation: Attestation) =
logScope: pcs = "send_attestation"
# https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/validator.md#broadcast-attestation
node.network.broadcast(
getMainnetAttestationTopic(node.forkDigest, attestation.data.index),
attestation)
beacon_attestations_sent.inc()
proc createAndSendAttestation(node: BeaconNode,
fork: Fork,
genesis_validators_root: Eth2Digest,
validator: AttachedValidator,
attestationData: AttestationData,
committeeLen: int,
indexInCommittee: int) {.async.} =
logScope: pcs = "send_attestation"
var attestation = await validator.produceAndSignAttestation(attestationData, committeeLen, indexInCommittee, fork, genesis_validators_root)
node.sendAttestation(attestation)
if node.config.dumpEnabled:
dump(node.config.dumpDir, attestation.data, validator.pubKey)
info "Attestation sent",
attestation = shortLog(attestation),
validator = shortLog(validator),
indexInCommittee = indexInCommittee,
cat = "consensus"
type
ValidatorInfoForMakeBeaconBlockKind* = enum
viValidator
viRandao_reveal
ValidatorInfoForMakeBeaconBlock* = object
case kind*: ValidatorInfoForMakeBeaconBlockKind
of viValidator: validator*: AttachedValidator
of viRandao_reveal: randao_reveal*: ValidatorSig
proc makeBeaconBlockForHeadAndSlot*(node: BeaconNode,
val_info: ValidatorInfoForMakeBeaconBlock,
validator_index: ValidatorIndex,
graffiti: Eth2Digest,
head: BlockRef,
slot: Slot):
tuple[message: Option[BeaconBlock], fork: Fork, genesis_validators_root: Eth2Digest] =
# Advance state to the slot that we're proposing for - this is the equivalent
# of running `process_slots` up to the slot of the new block.
node.blockPool.withState(
node.blockPool.tmpState, head.atSlot(slot)):
let (eth1data, deposits) =
if node.mainchainMonitor.isNil:
(get_eth1data_stub(state.eth1_deposit_index, slot.compute_epoch_at_slot()),
newSeq[Deposit]())
else:
node.mainchainMonitor.getBlockProposalData(state)
# TODO perhaps just making the enclosing function accept 2 different types at the
# same time and doing some compile-time branching logic is cleaner (without the
# need for the discriminated union)... but we need the `state` from `withState`
# in order to get the fork/root for the specific head/slot for the randao_reveal
# and it's causing problems when the function becomes a generic for 2 types...
proc getRandaoReveal(val_info: ValidatorInfoForMakeBeaconBlock): ValidatorSig =
if val_info.kind == viValidator:
return val_info.validator.genRandaoReveal(state.fork, state.genesis_validators_root, slot)
elif val_info.kind == viRandao_reveal:
return val_info.randao_reveal
let
poolPtr = unsafeAddr node.blockPool.dag # safe because restore is short-lived
func restore(v: var HashedBeaconState) =
# TODO address this ugly workaround - there should probably be a
# `state_transition` that takes a `StateData` instead and updates
# the block as well
doAssert v.addr == addr poolPtr.tmpState.data
poolPtr.tmpState = poolPtr.headState
var cache = get_empty_per_epoch_cache()
let message = makeBeaconBlock(
hashedState,
validator_index,
head.root,
getRandaoReveal(val_info),
eth1data,
graffiti,
node.attestationPool.getAttestationsForBlock(state),
deposits,
restore,
cache)
if message.isSome():
# TODO this restore is needed because otherwise tmpState will be internally
# inconsistent - it's blck will not be pointing to the block that
# created this state - we have to reset it here before `await` to avoid
# races.
restore(poolPtr.tmpState.data)
return (message, state.fork, state.genesis_validators_root)
proc proposeSignedBlock*(node: BeaconNode,
head: BlockRef,
validator: AttachedValidator,
newBlock: SignedBeaconBlock,
blockRoot: Eth2Digest): Future[BlockRef] {.async.} =
let newBlockRef = node.blockPool.add(blockRoot, newBlock)
if newBlockRef.isErr:
warn "Unable to add proposed block to block pool",
newBlock = shortLog(newBlock.message),
blockRoot = shortLog(blockRoot),
cat = "bug"
return head
info "Block proposed",
blck = shortLog(newBlock.message),
blockRoot = shortLog(newBlockRef[].root),
validator = shortLog(validator),
cat = "consensus"
if node.config.dumpEnabled:
dump(node.config.dumpDir, newBlock, newBlockRef[])
node.blockPool.withState(
node.blockPool.tmpState, newBlockRef[].atSlot(newBlockRef[].slot)):
dump(node.config.dumpDir, hashedState, newBlockRef[])
node.network.broadcast(node.topicBeaconBlocks, newBlock)
beacon_blocks_proposed.inc()
return newBlockRef[]
proc proposeBlock(node: BeaconNode,
validator: AttachedValidator,
validator_index: ValidatorIndex,
head: BlockRef,
slot: Slot): Future[BlockRef] {.async.} =
logScope: pcs = "block_proposal"
if head.slot >= slot:
# We should normally not have a head newer than the slot we're proposing for
# but this can happen if block proposal is delayed
warn "Skipping proposal, have newer head already",
headSlot = shortLog(head.slot),
headBlockRoot = shortLog(head.root),
slot = shortLog(slot),
cat = "fastforward"
return head
var graffiti: Eth2Digest
graffiti.data[0..<5] = toBytes("quack")
let valInfo = ValidatorInfoForMakeBeaconBlock(kind: viValidator, validator: validator)
let beaconBlockTuple = makeBeaconBlockForHeadAndSlot(node, valInfo, validator_index, graffiti, head, slot)
if not beaconBlockTuple.message.isSome():
return head # already logged elsewhere!
var
newBlock = SignedBeaconBlock(
message: beaconBlockTuple.message.get()
)
let blockRoot = hash_tree_root(newBlock.message)
newBlock.signature = await validator.signBlockProposal(
beaconBlockTuple.fork, beaconBlockTuple.genesis_validators_root, slot, blockRoot)
return await node.proposeSignedBlock(head, validator, newBlock, blockRoot)
proc handleAttestations(node: BeaconNode, head: BlockRef, slot: Slot) =
## Perform all attestations that the validators attached to this node should
## perform during the given slot
logScope: pcs = "on_attestation"
if slot + SLOTS_PER_EPOCH < head.slot:
# The latest block we know about is a lot newer than the slot we're being
# asked to attest to - this makes it unlikely that it will be included
# at all.
# TODO the oldest attestations allowed are those that are older than the
# finalized epoch.. also, it seems that posting very old attestations
# is risky from a slashing perspective. More work is needed here.
notice "Skipping attestation, head is too recent",
headSlot = shortLog(head.slot),
slot = shortLog(slot)
return
let attestationHead = head.atSlot(slot)
if head != attestationHead.blck:
# In rare cases, such as when we're busy syncing or just slow, we'll be
# attesting to a past state - we must then recreate the world as it looked
# like back then
notice "Attesting to a state in the past, falling behind?",
headSlot = shortLog(head.slot),
attestationHeadSlot = shortLog(attestationHead.slot),
attestationSlot = shortLog(slot)
trace "Checking attestations",
attestationHeadRoot = shortLog(attestationHead.blck.root),
attestationSlot = shortLog(slot),
cat = "attestation"
# Collect data to send before node.stateCache grows stale
var attestations: seq[tuple[
data: AttestationData, committeeLen, indexInCommittee: int,
validator: AttachedValidator]]
# We need to run attestations exactly for the slot that we're attesting to.
# In case blocks went missing, this means advancing past the latest block
# using empty slots as fillers.
# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/validator/0_beacon-chain-validator.md#validator-assignments
# TODO we could cache the validator assignment since it's valid for the entire
# epoch since it doesn't change, but that has to be weighed against
# the complexity of handling forks correctly - instead, we use an adapted
# version here that calculates the committee for a single slot only
node.blockPool.withState(node.blockPool.tmpState, attestationHead):
var cache = get_empty_per_epoch_cache()
let committees_per_slot = get_committee_count_at_slot(state, slot)
for committee_index in 0'u64..<committees_per_slot:
let committee = get_beacon_committee(
state, slot, committee_index.CommitteeIndex, cache)
for index_in_committee, validatorIdx in committee:
let validator = node.getAttachedValidator(state, validatorIdx)
if validator != nil:
let ad = makeAttestationData(state, slot, committee_index, blck.root)
attestations.add((ad, committee.len, index_in_committee, validator))
for a in attestations:
traceAsyncErrors createAndSendAttestation(
node, state.fork, state.genesis_validators_root, a.validator, a.data,
a.committeeLen, a.indexInCommittee)
proc handleProposal(node: BeaconNode, head: BlockRef, slot: Slot):
Future[BlockRef] {.async.} =
## Perform the proposal for the given slot, iff we have a validator attached
## that is supposed to do so, given the shuffling in head
# TODO here we advance the state to the new slot, but later we'll be
# proposing for it - basically, we're selecting proposer based on an
# empty slot
let proposer = node.blockPool.getProposer(head, slot)
if proposer.isNone():
return head
let validator = node.attachedValidators.getValidator(proposer.get()[1])
if validator != nil:
return await proposeBlock(node, validator, proposer.get()[0], head, slot)
debug "Expecting block proposal",
headRoot = shortLog(head.root),
slot = shortLog(slot),
proposer_index = proposer.get()[0],
proposer = shortLog(proposer.get()[1]),
cat = "consensus",
pcs = "wait_for_proposal"
return head
proc broadcastAggregatedAttestations(
node: BeaconNode, aggregationHead: BlockRef, aggregationSlot: Slot,
trailing_distance: uint64) =
# The index is via a
# locally attested validator. Unlike in handleAttestations(...) there's a
# single one at most per slot (because that's how aggregation attestation
# works), so the machinery that has to handle looping across, basically a
# set of locally attached validators is in principle not necessary, but a
# way to organize this. Then the private key for that validator should be
# the corresponding one -- whatver they are, they match.
let bs = BlockSlot(blck: aggregationHead, slot: aggregationSlot)
node.blockPool.withState(node.blockPool.tmpState, bs):
let
committees_per_slot = get_committee_count_at_slot(state, aggregationSlot)
var cache = get_empty_per_epoch_cache()
for committee_index in 0'u64..<committees_per_slot:
let committee = get_beacon_committee(
state, aggregationSlot, committee_index.CommitteeIndex, cache)
for index_in_committee, validatorIdx in committee:
let validator = node.getAttachedValidator(state, validatorIdx)
if validator != nil:
# This is slightly strange/inverted control flow, since really it's
# going to happen once per slot, but this is the best way to get at
# the validator index and private key pair. TODO verify it only has
# one isSome() with test.
let aggregateAndProof =
aggregate_attestations(node.attestationPool, state,
committee_index.CommitteeIndex,
# TODO https://github.com/status-im/nim-beacon-chain/issues/545
# this assumes in-process private keys
validator.privKey,
trailing_distance)
# Don't broadcast when, e.g., this node isn't an aggregator
if aggregateAndProof.isSome:
var signedAP = SignedAggregateAndProof(
message: aggregateAndProof.get,
# TODO Make the signing async here
signature: validator.signAggregateAndProof(
aggregateAndProof.get, state.fork,
state.genesis_validators_root))
node.network.broadcast(node.topicAggregateAndProofs, signedAP)
proc handleValidatorDuties*(
node: BeaconNode, lastSlot, slot: Slot) {.async.} =
## Perform validator duties - create blocks, vote and aggreagte existing votes
var head = node.updateHead()
if node.attachedValidators.count == 0:
# Nothing to do because we have no validator attached
return
if not node.isSynced(head):
notice "Node out of sync, skipping validator duties",
slot, headSlot = head.slot
return
var curSlot = lastSlot + 1
# Start by checking if there's work we should have done in the past that we
# can still meaningfully do
while curSlot < slot:
# TODO maybe even collect all work synchronously to avoid unnecessary
# state rewinds while waiting for async operations like validator
# signature..
notice "Catching up",
curSlot = shortLog(curSlot),
lastSlot = shortLog(lastSlot),
slot = shortLog(slot),
cat = "overload"
# For every slot we're catching up, we'll propose then send
# attestations - head should normally be advancing along the same branch
# in this case
# TODO what if we receive blocks / attestations while doing this work?
head = await handleProposal(node, head, curSlot)
# For each slot we missed, we need to send out attestations - if we were
# proposing during this time, we'll use the newly proposed head, else just
# keep reusing the same - the attestation that goes out will actually
# rewind the state to what it looked like at the time of that slot
# TODO smells like there's an optimization opportunity here
handleAttestations(node, head, curSlot)
curSlot += 1
head = await handleProposal(node, head, slot)
# We've been doing lots of work up until now which took time. Normally, we
# send out attestations at the slot thirds-point, so we go back to the clock
# to see how much time we need to wait.
# TODO the beacon clock might jump here also. It's probably easier to complete
# the work for the whole slot using a monotonic clock instead, then deal
# with any clock discrepancies once only, at the start of slot timer
# processing..
# https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/validator.md#attesting
# A validator should create and broadcast the attestation to the associated
# attestation subnet when either (a) the validator has received a valid
# block from the expected block proposer for the assigned slot or
# (b) one-third of the slot has transpired (`SECONDS_PER_SLOT / 3` seconds
# after the start of slot) -- whichever comes first.
template sleepToSlotOffsetWithHeadUpdate(extra: chronos.Duration, msg: static string) =
if await node.beaconClock.sleepToSlotOffset(extra, slot, msg):
# Time passed - we might need to select a new head in that case
head = node.updateHead()
sleepToSlotOffsetWithHeadUpdate(
seconds(int64(SECONDS_PER_SLOT)) div 3, "Waiting to send attestations")
handleAttestations(node, head, slot)
# https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/validator.md#broadcast-aggregate
# If the validator is selected to aggregate (is_aggregator), then they
# broadcast their best aggregate as a SignedAggregateAndProof to the global
# aggregate channel (beacon_aggregate_and_proof) two-thirds of the way
# through the slot-that is, SECONDS_PER_SLOT * 2 / 3 seconds after the start
# of slot.
if slot > 2:
sleepToSlotOffsetWithHeadUpdate(
seconds(int64(SECONDS_PER_SLOT * 2) div 3),
"Waiting to aggregate attestations")
const TRAILING_DISTANCE = 1
let
aggregationSlot = slot - TRAILING_DISTANCE
aggregationHead = getAncestorAt(head, aggregationSlot)
broadcastAggregatedAttestations(
node, aggregationHead, aggregationSlot, TRAILING_DISTANCE)