# beacon_chain # Copyright (c) 2018-2021 Status Research & Development GmbH # Licensed and distributed under either of # * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT). # * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0). # at your option. This file may not be copied, modified, or distributed except according to those terms. {.push raises: [Defect].} import # Standard library std/[os, osproc, sequtils, streams, tables], # Nimble packages stew/[assign2, objects], chronos, metrics, chronicles, json_serialization/std/[options, sets, net], serialization/errors, eth/db/kvstore, eth/keys, eth/p2p/discoveryv5/[protocol, enr], # Local modules ../spec/[ datatypes, digest, crypto, helpers, network, signatures, state_transition], ../conf, ../beacon_clock, ../consensus_object_pools/[ spec_cache, blockchain_dag, block_clearance, attestation_pool, exit_pool], ../eth1/eth1_monitor, ../networking/eth2_network, ".."/[beacon_node_common, beacon_node_types, version], ../ssz, ../ssz/sszdump, ../sync/sync_manager, ./slashing_protection, ./attestation_aggregation, ./validator_pool, ./keystore_management, ../gossip_processing/consensus_manager # Metrics for tracking attestation and beacon block loss const delayBuckets = [-Inf, -4.0, -2.0, -1.0, -0.5, -0.1, -0.05, 0.05, 0.1, 0.5, 1.0, 2.0, 4.0, 8.0, Inf] declareCounter beacon_attestations_sent, "Number of beacon chain attestations sent by this peer" declareHistogram beacon_attestation_sent_delay, "Time(s) between slot start and attestation sent moment", buckets = delayBuckets declareCounter beacon_blocks_proposed, "Number of beacon chain blocks sent by this peer" declareGauge(attached_validator_balance, "Validator balance at slot end of the first 64 validators, in Gwei", labels = ["pubkey"]) declarePublicGauge(attached_validator_balance_total, "Validator balance of all attached validators, in Gwei") logScope: topics = "beacval" proc findValidator(validators: auto, pubKey: ValidatorPubKey): Option[ValidatorIndex] = let idx = 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 notice "Validator deposit not yet processed, monitoring", pubKey none(ValidatorIndex) else: some(idx.ValidatorIndex) proc addLocalValidator(node: BeaconNode, stateData: StateData, privKey: ValidatorPrivKey) = let pubKey = privKey.toPubKey() node.attachedValidators[].addLocalValidator( pubKey, privKey, findValidator(getStateField(stateData, validators), pubKey)) proc addLocalValidators*(node: BeaconNode) = for validatorKey in node.config.validatorKeys: node.addLocalValidator node.chainDag.headState, validatorKey proc addRemoteValidators*(node: BeaconNode) {.raises: [Defect, OSError, IOError].} = # load all the validators from the child process - loop until `end` var line = newStringOfCap(120).TaintedString while line != "end" and running(node.vcProcess): if node.vcProcess.outputStream.readLine(line) and line != "end": let key = ValidatorPubKey.fromHex(line).get() index = findValidator( getStateField(node.chainDag.headState, validators), key) let v = AttachedValidator(pubKey: key, index: index, kind: ValidatorKind.remote, connection: ValidatorConnection( inStream: node.vcProcess.inputStream, outStream: node.vcProcess.outputStream, pubKeyStr: $key)) node.attachedValidators[].addRemoteValidator(key, v) proc getAttachedValidator*(node: BeaconNode, pubkey: ValidatorPubKey): AttachedValidator = node.attachedValidators[].getValidator(pubkey) proc getAttachedValidator*(node: BeaconNode, state_validators: auto, idx: ValidatorIndex): AttachedValidator = if idx < state_validators.len.ValidatorIndex: let validator = node.getAttachedValidator(state_validators[idx].pubkey) if validator != nil and validator.index != some(idx.ValidatorIndex): # Update index, in case the validator was activated! notice "Validator activated", pubkey = validator.pubkey, index = idx validator.index = some(idx.ValidatorIndex) validator else: warn "Validator index out of bounds", idx, validators = state_validators.len nil proc getAttachedValidator*(node: BeaconNode, epochRef: EpochRef, idx: ValidatorIndex): AttachedValidator = if idx < epochRef.validator_keys.len.ValidatorIndex: let validator = node.getAttachedValidator(epochRef.validator_keys[idx]) if validator != nil and validator.index != some(idx.ValidatorIndex): # Update index, in case the validator was activated! notice "Validator activated", pubkey = validator.pubkey, index = idx validator.index = some(idx.ValidatorIndex) validator else: warn "Validator index out of bounds", idx, epoch = epochRef.epoch, validators = epochRef.validator_keys.len nil 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: MaxEmptySlotCount should likely involve the weak subjectivity period. # 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, subnet_id: SubnetId, checkSignature: bool): Future[bool] {.async.} = # Validate attestation before sending it via gossip - validation will also # register the attestation with the attestation pool. Notably, although # libp2p calls the data handler for any subscription on the subnet # topic, it does not perform validation. let ok = await node.processor.attestationValidator( attestation, subnet_id, checkSignature) return case ok of ValidationResult.Accept: node.network.broadcast( getAttestationTopic(node.forkDigest, subnet_id), attestation) beacon_attestations_sent.inc() true else: notice "Produced attestation failed validation", attestation = shortLog(attestation), result = $ok false proc sendVoluntaryExit*(node: BeaconNode, exit: SignedVoluntaryExit) = node.network.broadcast(getVoluntaryExitsTopic(node.forkDigest), exit) proc sendAttesterSlashing*(node: BeaconNode, slashing: AttesterSlashing) = node.network.broadcast(getAttesterSlashingsTopic(node.forkDigest), slashing) proc sendProposerSlashing*(node: BeaconNode, slashing: ProposerSlashing) = node.network.broadcast(getProposerSlashingsTopic(node.forkDigest), slashing) proc sendAttestation*(node: BeaconNode, attestation: Attestation): Future[bool] = # For the validator API, which doesn't supply the subnet id. let attestationBlck = node.chainDag.getRef(attestation.data.beacon_block_root) if attestationBlck.isNil: debug "Attempt to send attestation without corresponding block" return let epochRef = node.chainDag.getEpochRef( attestationBlck, attestation.data.target.epoch) subnet_id = compute_subnet_for_attestation( get_committee_count_per_slot(epochRef), attestation.data.slot, attestation.data.index.CommitteeIndex) node.sendAttestation(attestation, subnet_id, checkSignature = true) proc createAndSendAttestation(node: BeaconNode, fork: Fork, genesis_validators_root: Eth2Digest, validator: AttachedValidator, attestationData: AttestationData, committeeLen: int, indexInCommittee: int, subnet_id: SubnetId) {.async.} = try: var attestation = await validator.produceAndSignAttestation( attestationData, committeeLen, indexInCommittee, fork, genesis_validators_root) let ok = await node.sendAttestation( attestation, subnet_id, checkSignature = false) if not ok: # Logged in sendAttestation return let sent = node.beaconClock.now() if node.config.dumpEnabled: dump(node.config.dumpDirOutgoing, attestation.data, validator.pubKey) let wallTime = node.beaconClock.now() let deadline = attestationData.slot.toBeaconTime() + seconds(int(SECONDS_PER_SLOT div 3)) let (delayStr, delaySecs) = if wallTime < deadline: ("-" & $(deadline - wallTime), -toFloatSeconds(deadline - wallTime)) else: ($(wallTime - deadline), toFloatSeconds(wallTime - deadline)) notice "Attestation sent", attestation = shortLog(attestation), validator = shortLog(validator), delay = delayStr, indexInCommittee = indexInCommittee beacon_attestation_sent_delay.observe(delaySecs) except CatchableError as exc: # An error could happen here when the signature task fails - we must # not leak the exception because this is an asyncSpawn task notice "Error sending attestation", err = exc.msg proc getBlockProposalEth1Data*(node: BeaconNode, stateData: StateData): BlockProposalEth1Data = if node.eth1Monitor.isNil: var pendingDepositsCount = getStateField(stateData, eth1_data).deposit_count - getStateField(stateData, eth1_deposit_index) if pendingDepositsCount > 0: result.hasMissingDeposits = true else: result.vote = getStateField(stateData, eth1_data) else: let finalizedEpochRef = node.chainDag.getFinalizedEpochRef() result = node.eth1Monitor.getBlockProposalData( stateData.data.data, finalizedEpochRef.eth1_data, finalizedEpochRef.eth1_deposit_index) proc makeBeaconBlockForHeadAndSlot*(node: BeaconNode, randao_reveal: ValidatorSig, validator_index: ValidatorIndex, graffiti: GraffitiBytes, head: BlockRef, slot: Slot): Option[BeaconBlock] = # Advance state to the slot that we're proposing for let proposalState = assignClone(node.chainDag.headState) proposalStateAddr = unsafeAddr proposalState[] node.chainDag.withState(proposalState[], head.atSlot(slot)): let eth1Proposal = node.getBlockProposalEth1Data(stateData) poolPtr = unsafeAddr node.chainDag # safe because restore is short-lived if eth1Proposal.hasMissingDeposits: error "Eth1 deposits not available. Skipping block proposal", slot return none(BeaconBlock) 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 proposalStateAddr.data assign(proposalStateAddr[], poolPtr.headState) makeBeaconBlock( node.runtimePreset, hashedState, validator_index, head.root, randao_reveal, eth1Proposal.vote, graffiti, node.attestationPool[].getAttestationsForBlock(state, cache), eth1Proposal.deposits, node.exitPool[].getProposerSlashingsForBlock(), node.exitPool[].getAttesterSlashingsForBlock(), node.exitPool[].getVoluntaryExitsForBlock(), restore, cache) proc proposeSignedBlock*(node: BeaconNode, head: BlockRef, validator: AttachedValidator, newBlock: SignedBeaconBlock): BlockRef = let newBlockRef = node.chainDag.addRawBlock(node.quarantine, newBlock) do ( blckRef: BlockRef, trustedBlock: TrustedSignedBeaconBlock, epochRef: EpochRef, state: HashedBeaconState): # Callback add to fork choice if signed block valid (and becomes trusted) node.attestationPool[].addForkChoice( epochRef, blckRef, trustedBlock.message, node.beaconClock.now().slotOrZero()) if newBlockRef.isErr: warn "Unable to add proposed block to block pool", newBlock = shortLog(newBlock.message), blockRoot = shortLog(newBlock.root) return head notice "Block proposed", blck = shortLog(newBlock.message), blockRoot = shortLog(newBlockRef[].root), validator = shortLog(validator) if node.config.dumpEnabled: dump(node.config.dumpDirOutgoing, newBlock) 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.} = 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) return head let fork = getStateField(node.chainDag.headState, fork) genesis_validators_root = getStateField(node.chainDag.headState, genesis_validators_root) randao = await validator.genRandaoReveal( fork, genesis_validators_root, slot) message = makeBeaconBlockForHeadAndSlot( node, randao, validator_index, node.graffitiBytes, head, slot) if not message.isSome(): return head # already logged elsewhere! var newBlock = SignedBeaconBlock( message: message.get() ) newBlock.root = hash_tree_root(newBlock.message) # TODO: recomputed in block proposal let signing_root = compute_block_root( fork, genesis_validators_root, slot, newBlock.root) let notSlashable = node.attachedValidators .slashingProtection .registerBlock(validator_index, validator.pubkey, slot, signing_root) if notSlashable.isErr: warn "Slashing protection activated", validator = validator.pubkey, slot = slot, existingProposal = notSlashable.error return head newBlock.signature = await validator.signBlockProposal( fork, genesis_validators_root, slot, newBlock.root) return node.proposeSignedBlock(head, validator, newBlock) proc handleAttestations(node: BeaconNode, head: BlockRef, slot: Slot) = ## Perform all attestations that the validators attached to this node should ## perform during the given slot 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. warn "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) # 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/v1.0.1/specs/phase0/validator.md#validator-assignments let epochRef = node.chainDag.getEpochRef( attestationHead.blck, slot.compute_epoch_at_slot()) committees_per_slot = get_committee_count_per_slot(epochRef) fork = getStateField(node.chainDag.headState, fork) genesis_validators_root = getStateField(node.chainDag.headState, genesis_validators_root) for committee_index in get_committee_indices(epochRef): let committee = get_beacon_committee(epochRef, slot, committee_index) for index_in_committee, validator_index in committee: let validator = node.getAttachedValidator(epochRef, validator_index) if validator == nil: continue let data = makeAttestationData(epochRef, attestationHead, committee_index) # TODO signing_root is recomputed in produceAndSignAttestation/signAttestation just after signing_root = compute_attestation_root( fork, genesis_validators_root, data) registered = node.attachedValidators .slashingProtection .registerAttestation( validator_index, validator.pubkey, data.source.epoch, data.target.epoch, signing_root) if registered.isOk(): let subnet_id = compute_subnet_for_attestation( committees_per_slot, data.slot, data.index.CommitteeIndex) asyncSpawn createAndSendAttestation( node, fork, genesis_validators_root, validator, data, committee.len(), index_in_committee, subnet_id) else: warn "Slashing protection activated for attestation", validator = validator.pubkey, badVoteDetails = $registered.error() 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 at that slot for the given ## head - to compute the proposer, we need to advance a state to the given ## slot let proposer = node.chainDag.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]) return head proc broadcastAggregatedAttestations( node: BeaconNode, aggregationHead: BlockRef, aggregationSlot: Slot) {.async.} = # 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 epochRef = node.chainDag.getEpochRef(aggregationHead, aggregationSlot.epoch) fork = getStateField(node.chainDag.headState, fork) genesis_validators_root = getStateField(node.chainDag.headState, genesis_validators_root) committees_per_slot = get_committee_count_per_slot(epochRef) var slotSigs: seq[Future[ValidatorSig]] = @[] slotSigsData: seq[tuple[committee_index: uint64, validator_idx: ValidatorIndex, v: AttachedValidator]] = @[] for committee_index in 0'u64..= state.balances.lenu64: debug "Cannot get validator balance, index out of bounds", pubkey = shortLog(v.pubkey), index = v.index.get(), balances = state.balances.len, stateRoot = node.chainDag.headState.data.root 0.Gwei else: state.balances[v.index.get()] if i < 64: attached_validator_balance.set( balance.toGaugeValue, labelValues = [shortLog(v.pubkey)]) else: inc i total += balance node.attachedValidatorBalanceTotal = total attached_validator_balance_total.set(total.toGaugeValue) else: discard proc handleValidatorDuties*(node: BeaconNode, lastSlot, slot: Slot) {.async.} = ## Perform validator duties - create blocks, vote and aggregate existing votes if node.attachedValidators[].count == 0: # Nothing to do because we have no validator attached return # The chainDag head might be updated by sync while we're working due to the # await calls, thus we use a local variable to keep the logic straight here var head = node.chainDag.head if not node.isSynced(head): notice "Syncing in progress; skipping validator duties for now", slot, headSlot = head.slot # Rewards will be growing though, as we sync.. updateValidatorMetrics(node) return var curSlot = lastSlot + 1 # If broadcastStartEpoch is 0, it hasn't had time to initialize yet, which # means that it'd be okay not to continue, but it won't gossip regardless. if curSlot.epoch < node.processor[].doppelgangerDetection.broadcastStartEpoch and node.config.doppelgangerDetection: debug "Waiting to gossip out to detect potential duplicate validators", broadcastStartEpoch = node.processor[].doppelgangerDetection.broadcastStartEpoch return # Start by checking if there's work we should have done in the past that we # can still meaningfully do while curSlot < slot: notice "Catching up on validator duties", curSlot = shortLog(curSlot), lastSlot = shortLog(lastSlot), slot = shortLog(slot) # 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 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 handleAttestations(node, head, curSlot) curSlot += 1 head = await handleProposal(node, head, slot) # https://github.com/ethereum/eth2.0-specs/blob/v1.0.1/specs/phase0/validator.md#attesting # Milliseconds to wait from the start of the slot before sending out # attestations const attestationOffset = SECONDS_PER_SLOT.int64 * 1000 div 3 let # The latest point in time when we'll be sending out attestations attestationCutoffTime = slot.toBeaconTime(millis(attestationOffset)) attestationCutoff = node.beaconClock.fromNow(attestationCutoffTime) if attestationCutoff.inFuture: debug "Waiting to send attestations", head = shortLog(head), attestationCutoff = shortLog(attestationCutoff.offset) # Wait either for the block or the attestation cutoff time to arrive if await node.consensusManager[].expectBlock(slot).withTimeout(attestationCutoff.offset): # The expected block arrived (or expectBlock was called again which # shouldn't happen as this is the only place we use it) - in our async # loop however, we might have been doing other processing that caused delays # here so we'll cap the waiting to the time when we would have sent out # attestations had the block not arrived. # An opposite case is that we received (or produced) a block that has # not yet reached our neighbours. To protect against our attestations # being dropped (because the others have not yet seen the block), we'll # impose a minimum delay of 250ms. The delay is enforced only when we're # not hitting the "normal" cutoff time for sending out attestations. const afterBlockDelay = 250 let afterBlockTime = node.beaconClock.now() + millis(afterBlockDelay) afterBlockCutoff = node.beaconClock.fromNow( min(afterBlockTime, attestationCutoffTime)) if afterBlockCutoff.inFuture: debug "Got block, waiting to send attestations", head = shortLog(head), afterBlockCutoff = shortLog(afterBlockCutoff.offset) await sleepAsync(afterBlockCutoff.offset) # Time passed - we might need to select a new head in that case node.consensusManager[].updateHead(slot) head = node.chainDag.head handleAttestations(node, head, slot) updateValidatorMetrics(node) # the important stuff is done, update the vanity numbers # https://github.com/ethereum/eth2.0-specs/blob/v1.0.1/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: let aggregateWaitTime = node.beaconClock.fromNow( slot.toBeaconTime(seconds(int64(SECONDS_PER_SLOT * 2) div 3))) if aggregateWaitTime.inFuture: debug "Waiting to send aggregate attestations", aggregateWaitTime = shortLog(aggregateWaitTime.offset) await sleepAsync(aggregateWaitTime.offset) await broadcastAggregatedAttestations(node, head, slot) if node.eth1Monitor != nil and (slot mod SLOTS_PER_EPOCH) == 0: let finalizedEpochRef = node.chainDag.getFinalizedEpochRef() discard node.eth1Monitor.trackFinalizedState( finalizedEpochRef.eth1_data, finalizedEpochRef.eth1_deposit_index)