# beacon_chain # Copyright (c) 2019-2022 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. {.push raises: [Defect].} # References to `vFuture` refer to the pre-release proposal of the libp2p based # light client sync protocol. Conflicting release versions are not in use. # https://github.com/ethereum/consensus-specs/pull/2802 import # Status chronicles, chronos, metrics, stew/results, # Internals ../spec/datatypes/[phase0, altair, bellatrix], ../spec/[ beaconstate, state_transition_block, forks, helpers, network, signatures], ../consensus_object_pools/[ attestation_pool, blockchain_dag, block_quarantine, exit_pool, spec_cache, light_client_pool, sync_committee_msg_pool], ".."/[beacon_clock], ./batch_validation from libp2p/protocols/pubsub/pubsub import ValidationResult export results, ValidationResult logScope: topics = "gossip_checks" declareCounter beacon_attestations_dropped_queue_full, "Number of attestations dropped because queue is full" declareCounter beacon_aggregates_dropped_queue_full, "Number of aggregates dropped because queue is full" declareCounter beacon_sync_messages_dropped_queue_full, "Number of sync committee messages dropped because queue is full" declareCounter beacon_contributions_dropped_queue_full, "Number of sync committee contributions dropped because queue is full" # This result is a little messy in that it returns Result.ok for # ValidationResult.Accept and an err for the others - this helps transport # an error message to callers but could arguably be done in an cleaner way. type ValidationError* = (ValidationResult, cstring) template errIgnore*(msg: cstring): untyped = err((ValidationResult.Ignore, cstring msg)) template errReject*(msg: cstring): untyped = err((ValidationResult.Reject, cstring msg)) # Internal checks # ---------------------------------------------------------------- func check_attestation_block( pool: AttestationPool, attestationSlot: Slot, blck: BlockRef): Result[void, ValidationError] = # The voted-for block must be a descendant of the finalized block, thus it # must at least as new than the finalized checkpoint - in theory it could be # equal, but then we're voting for an already-finalized block which is pretty # useless - other blocks that are not rooted in the finalized chain will be # pruned by the chain dag, and thus we can no longer get a BlockRef for them if not (blck.slot > pool.dag.finalizedHead.slot): return errIgnore("Voting for already-finalized block") # The attestation shouldn't be voting for a block that didn't exist at the # time - not in spec, but hard to reason about if not (attestationSlot >= blck.slot): return errIgnore("Voting for block that didn't exist at the time") # We'll also cap it at 4 epochs which is somewhat arbitrary, but puts an # upper bound on the processing done to validate the attestation # TODO revisit with less arbitrary approach if not ((attestationSlot - blck.slot) <= uint64(4 * SLOTS_PER_EPOCH)): return errIgnore("Voting for very old block") ok() func check_propagation_slot_range( msgSlot: Slot, wallTime: BeaconTime): Result[Slot, ValidationError] = let futureSlot = (wallTime + MAXIMUM_GOSSIP_CLOCK_DISPARITY).toSlot() if not futureSlot.afterGenesis or msgSlot > futureSlot.slot: return errIgnore("Attestation slot in the future") let pastSlot = (wallTime - MAXIMUM_GOSSIP_CLOCK_DISPARITY).toSlot() # https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/p2p-interface.md#configuration # The spec value of ATTESTATION_PROPAGATION_SLOT_RANGE is 32, but it can # retransmit attestations on the cusp of being out of spec, and which by # the time they reach their destination might be out of spec. const ATTESTATION_PROPAGATION_SLOT_RANGE = 28 if pastSlot.afterGenesis and msgSlot + ATTESTATION_PROPAGATION_SLOT_RANGE < pastSlot.slot: return errIgnore("Attestation slot in the past") ok(msgSlot) func check_beacon_and_target_block( pool: var AttestationPool, data: AttestationData): Result[BlockSlot, ValidationError] = # The block being voted for (data.beacon_block_root) passes validation - by # extension, the target block must at that point also pass validation. # The target block is returned. # We rely on the chain DAG to have been validated, so check for the existence # of the block in the pool. let blck = pool.dag.getBlockRef(data.beacon_block_root).valueOr: pool.quarantine[].addMissing(data.beacon_block_root) return errIgnore("Attestation block unknown") # Not in spec - check that rewinding to the state is sane ? check_attestation_block(pool, data.slot, blck) # [REJECT] The attestation's target block is an ancestor of the block named # in the LMD vote -- i.e. get_ancestor(store, # attestation.data.beacon_block_root, # compute_start_slot_at_epoch(attestation.data.target.epoch)) == # attestation.data.target.root # the sanity of target.epoch has been checked by check_attestation_slot_target let target = blck.atSlot(data.target.epoch.start_slot()) if isNil(target.blck): # Shouldn't happen - we've checked that the target epoch is within range # already return errReject("Attestation target block not found") if not (target.blck.root == data.target.root): return errReject( "Attestation target block not the correct ancestor of LMD vote block") ok(target) func check_aggregation_count( attestation: Attestation, singular: bool): Result[void, ValidationError] = let ones = attestation.aggregation_bits.countOnes() if singular and ones != 1: return errReject("Attestation must have a single attestation bit set") elif not singular and ones < 1: return errReject("Attestation must have at least one attestation bit set") ok() func check_attestation_subnet( epochRef: EpochRef, slot: Slot, committee_index: CommitteeIndex, subnet_id: SubnetId): Result[void, ValidationError] = let expectedSubnet = compute_subnet_for_attestation( get_committee_count_per_slot(epochRef), slot, committee_index) if expectedSubnet != subnet_id: return errReject("Attestation not on the correct subnet") ok() # Gossip Validation # ---------------------------------------------------------------- template checkedReject(msg: cstring): untyped = if verifyFinalization in pool.dag.updateFlags: # This doesn't depend on the wall clock or the exact state of the DAG; it's # an internal consistency/correctness check only, and effectively never has # false positives. These don't, for example, arise from timeouts. raiseAssert $msg errReject(msg) template checkedReject(error: ValidationError): untyped = doAssert error[0] == ValidationResult.Reject if verifyFinalization in pool.dag.updateFlags: # This doesn't depend on the wall clock or the exact state of the DAG; it's # an internal consistency/correctness check only, and effectively never has # false positives. These don't, for example, arise from timeouts. raiseAssert $error[1] err(error) template validateBeaconBlockBellatrix( signed_beacon_block: phase0.SignedBeaconBlock | altair.SignedBeaconBlock, parent: BlockRef): untyped = discard # https://github.com/ethereum/consensus-specs/blob/v1.1.7/specs/merge/p2p-interface.md#beacon_block template validateBeaconBlockBellatrix( signed_beacon_block: bellatrix.SignedBeaconBlock, parent: BlockRef): untyped = # If the execution is enabled for the block -- i.e. # is_execution_enabled(state, block.body) then validate the following: let executionEnabled = if signed_beacon_block.message.body.execution_payload != default(ExecutionPayload): true elif dag.getEpochRef(parent, parent.slot.epoch, true).expect( "parent EpochRef doesn't fail").merge_transition_complete: # Should usually be inexpensive, but could require cache refilling - the # parent block can be no older than the latest finalized block true else: # Somewhat more expensive fallback, with database I/O, but should be # mostly relevant around merge transition epochs. It's possible that # the previous block is phase 0 or Altair, if this is the transition # block itself. let blockData = dag.getForkedBlock(parent.bid) if blockData.isOk(): case blockData.get().kind: of BeaconBlockFork.Phase0: false of BeaconBlockFork.Altair: false of BeaconBlockFork.Bellatrix: # https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/bellatrix/beacon-chain.md#process_execution_payload # shows how this gets folded into the state each block; checking this # is equivalent, without ever requiring state replay or any similarly # expensive computation. blockData.get().bellatrixData.message.body.execution_payload != default(ExecutionPayload) else: warn "Cannot load block parent, assuming execution is disabled", parent = shortLog(parent) false if executionEnabled: # [REJECT] The block's execution payload timestamp is correct with respect # to the slot -- i.e. execution_payload.timestamp == # compute_timestamp_at_slot(state, block.slot). let timestampAtSlot = withState(dag.headState): compute_timestamp_at_slot(state.data, signed_beacon_block.message.slot) if not (signed_beacon_block.message.body.execution_payload.timestamp == timestampAtSlot): quarantine[].addUnviable(signed_beacon_block.root) return errReject("BeaconBlock: Mismatched execution payload timestamp") # https://github.com/ethereum/consensus-specs/blob/v1.1.9/specs/phase0/p2p-interface.md#beacon_block # https://github.com/ethereum/consensus-specs/blob/v1.1.8/specs/bellatrix/p2p-interface.md#beacon_block proc validateBeaconBlock*( dag: ChainDAGRef, quarantine: ref Quarantine, signed_beacon_block: phase0.SignedBeaconBlock | altair.SignedBeaconBlock | bellatrix.SignedBeaconBlock, wallTime: BeaconTime, flags: UpdateFlags): Result[void, ValidationError] = # In general, checks are ordered from cheap to expensive. Especially, crypto # verification could be quite a bit more expensive than the rest. This is an # externally easy-to-invoke function by tossing network packets at the node. # [IGNORE] The block is not from a future slot (with a # MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance) -- i.e. validate that # signed_beacon_block.message.slot <= current_slot (a client MAY queue future # blocks for processing at the appropriate slot). if not (signed_beacon_block.message.slot <= (wallTime + MAXIMUM_GOSSIP_CLOCK_DISPARITY).slotOrZero): return errIgnore("BeaconBlock: slot too high") # [IGNORE] The block is from a slot greater than the latest finalized slot -- # i.e. validate that signed_beacon_block.message.slot > # compute_start_slot_at_epoch(state.finalized_checkpoint.epoch) if not (signed_beacon_block.message.slot > dag.finalizedHead.slot): return errIgnore("BeaconBlock: slot already finalized") # [IGNORE] The block is the first block with valid signature received for the # proposer for the slot, signed_beacon_block.message.slot. # # While this condition is similar to the proposer slashing condition at # https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/validator.md#proposer-slashing # it's not identical, and this check does not address slashing: # # (1) The beacon blocks must be conflicting, i.e. different, for the same # slot and proposer. This check also catches identical blocks. # # (2) By this point in the function, it's not been checked whether they're # signed yet. As in general, expensive checks should be deferred, this # would add complexity not directly relevant this function. # # (3) As evidenced by point (1), the similarity in the validation condition # and slashing condition, while not coincidental, aren't similar enough # to combine, as one or the other might drift. # # (4) Furthermore, this function, as much as possible, simply returns a yes # or no answer, without modifying other state for p2p network interface # validation. Complicating this interface, for the sake of sharing only # couple lines of code, wouldn't be worthwhile. # # TODO might check unresolved/orphaned blocks too, and this might not see all # blocks at a given slot (though, in theory, those get checked elsewhere), or # adding metrics that count how often these conditions occur. if dag.containsForkBlock(signed_beacon_block.root): # The gossip algorithm itself already does one round of hashing to find # already-seen data, but it is fairly aggressive about forgetting about # what it has seen already # "[IGNORE] The block is the first block ..." return errIgnore("BeaconBlock: already seen") let slotBlock = getBlockIdAtSlot(dag, signed_beacon_block.message.slot) if slotBlock.isSome() and slotBlock.get().isProposed() and slotBlock.get().bid.slot == signed_beacon_block.message.slot: let curBlock = dag.getForkedBlock(slotBlock.get().bid) if curBlock.isOk(): let data = curBlock.get() if getForkedBlockField(data, proposer_index) == signed_beacon_block.message.proposer_index and data.signature.toRaw() != signed_beacon_block.signature.toRaw(): return errIgnore("BeaconBlock: already proposed in the same slot") # [IGNORE] The block's parent (defined by block.parent_root) has been seen # (via both gossip and non-gossip sources) (a client MAY queue blocks for # processing once the parent block is retrieved). # # And implicitly: # [REJECT] The block's parent (defined by block.parent_root) passes validation. let parent = dag.getBlockRef(signed_beacon_block.message.parent_root).valueOr: if signed_beacon_block.message.parent_root in quarantine[].unviable: quarantine[].addUnviable(signed_beacon_block.root) return errReject("BeaconBlock: parent from unviable fork") # When the parent is missing, we can't validate the block - we'll queue it # in the quarantine for later processing if not quarantine[].addOrphan( dag.finalizedHead.slot, ForkedSignedBeaconBlock.init(signed_beacon_block)): debug "Block quarantine full" return errIgnore("BeaconBlock: Parent not found") # [REJECT] The block is from a higher slot than its parent. if not (signed_beacon_block.message.slot > parent.bid.slot): return errReject("BeaconBlock: block not from higher slot than its parent") # [REJECT] The current finalized_checkpoint is an ancestor of block -- i.e. # get_ancestor(store, block.parent_root, # compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)) == # store.finalized_checkpoint.root let finalized_checkpoint = getStateField(dag.headState, finalized_checkpoint) ancestor = get_ancestor(parent, finalized_checkpoint.epoch.start_slot) if ancestor.isNil: # This shouldn't happen: we should always be able to trace the parent back # to the finalized checkpoint (else it wouldn't be in the DAG) return errIgnore("BeaconBlock: Can't find ancestor") if not ( finalized_checkpoint.root == ancestor.root or finalized_checkpoint.root.isZero): quarantine[].addUnviable(signed_beacon_block.root) return errReject("BeaconBlock: Finalized checkpoint not an ancestor") # [REJECT] The block is proposed by the expected proposer_index for the # block's slot in the context of the current shuffling (defined by # parent_root/slot). If the proposer_index cannot immediately be verified # against the expected shuffling, the block MAY be queued for later # processing while proposers for the block's branch are calculated -- in such # a case do not REJECT, instead IGNORE this message. let proposer = getProposer(dag, parent, signed_beacon_block.message.slot) if proposer.isNone: warn "cannot compute proposer for message" return errIgnore("BeaconBlock: Cannot compute proposer") # internal issue if uint64(proposer.get()) != signed_beacon_block.message.proposer_index: quarantine[].addUnviable(signed_beacon_block.root) return errReject("BeaconBlock: Unexpected proposer proposer") # [REJECT] The proposer signature, signed_beacon_block.signature, is valid # with respect to the proposer_index pubkey. if not verify_block_signature( dag.forkAtEpoch(signed_beacon_block.message.slot.epoch), getStateField(dag.headState, genesis_validators_root), signed_beacon_block.message.slot, signed_beacon_block.root, dag.validatorKey(proposer.get()).get(), signed_beacon_block.signature): quarantine[].addUnviable(signed_beacon_block.root) return errReject("BeaconBlock: Invalid proposer signature") validateBeaconBlockBellatrix(signed_beacon_block, parent) ok() # https://github.com/ethereum/consensus-specs/blob/v1.1.9/specs/phase0/p2p-interface.md#beacon_attestation_subnet_id proc validateAttestation*( pool: ref AttestationPool, batchCrypto: ref BatchCrypto, attestation: Attestation, wallTime: BeaconTime, subnet_id: SubnetId, checkSignature: bool): Future[Result[ tuple[attesting_index: ValidatorIndex, sig: CookedSig], ValidationError]] {.async.} = # Some of the checks below have been reordered compared to the spec, to # perform the cheap checks first - in particular, we want to avoid loading # an `EpochRef` and checking signatures. This reordering might lead to # different IGNORE/REJECT results in turn affecting gossip scores. # [REJECT] The attestation's epoch matches its target -- i.e. # attestation.data.target.epoch == # compute_epoch_at_slot(attestation.data.slot) let slot = block: let v = check_attestation_slot_target(attestation.data) if v.isErr(): return errReject(v.error()) v.get() # attestation.data.slot is within the last ATTESTATION_PROPAGATION_SLOT_RANGE # slots (within a MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance) -- i.e. # attestation.data.slot + ATTESTATION_PROPAGATION_SLOT_RANGE >= current_slot # >= attestation.data.slot (a client MAY queue future attestations for # processing at the appropriate slot). block: let v = check_propagation_slot_range(slot, wallTime) # [IGNORE] if v.isErr(): return err(v.error()) # The attestation is unaggregated -- that is, it has exactly one # participating validator (len([bit for bit in attestation.aggregation_bits # if bit == 0b1]) == 1). block: let v = check_aggregation_count(attestation, singular = true) # [REJECT] if v.isErr(): return checkedReject(v.error) # The block being voted for (attestation.data.beacon_block_root) has been seen # (via both gossip and non-gossip sources) (a client MAY queue attestations for # processing once block is retrieved). # The block being voted for (attestation.data.beacon_block_root) passes # validation. # [IGNORE] if block is unseen so far and enqueue it in missing blocks let target = block: let v = check_beacon_and_target_block(pool[], attestation.data) # [IGNORE/REJECT] if v.isErr(): return err(v.error) v.get() # The following rule follows implicitly from that we clear out any # unviable blocks from the chain dag: # # The current finalized_checkpoint is an ancestor of the block defined by # attestation.data.beacon_block_root -- i.e. get_ancestor(store, # attestation.data.beacon_block_root, # compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)) == # store.finalized_checkpoint.root let epochRef = block: let tmp = pool.dag.getEpochRef(target.blck, target.slot.epoch, false) if isErr(tmp): # shouldn't happen since we verified target warn "No EpochRef for attestation", attestation = shortLog(attestation), target = shortLog(target) return errIgnore("Attestation: no EpochRef") tmp.get() # [REJECT] The committee index is within the expected range -- i.e. # data.index < get_committee_count_per_slot(state, data.target.epoch). let committee_index = block: let idx = epochRef.get_committee_index(attestation.data.index) if idx.isErr(): return checkedReject("Attestation: committee index not within expected range") idx.get() # [REJECT] The attestation is for the correct subnet -- i.e. # compute_subnet_for_attestation(committees_per_slot, # attestation.data.slot, attestation.data.index) == subnet_id, where # committees_per_slot = get_committee_count_per_slot(state, # attestation.data.target.epoch), which may be pre-computed along with the # committee information for the signature check. block: let v = check_attestation_subnet( epochRef, attestation.data.slot, committee_index, subnet_id) # [REJECT] if v.isErr(): return err(v.error) # [REJECT] The number of aggregation bits matches the committee size -- i.e. # len(attestation.aggregation_bits) == len(get_beacon_committee(state, # data.slot, data.index)). # # This uses the same epochRef as data.target.epoch, because the attestation's # epoch matches its target and attestation.data.target.root is an ancestor of # attestation.data.beacon_block_root. if not (attestation.aggregation_bits.lenu64 == get_beacon_committee_len( epochRef, attestation.data.slot, committee_index)): return checkedReject( "Attestation: number of aggregation bits and committee size mismatch") let fork = pool.dag.forkAtEpoch(attestation.data.slot.epoch) genesis_validators_root = getStateField(pool.dag.headState, genesis_validators_root) attesting_index = get_attesting_indices_one( epochRef, slot, committee_index, attestation.aggregation_bits) # The number of aggregation bits matches the committee size, which ensures # this condition holds. doAssert attesting_index.isSome(), "We've checked bits length and one count already" let validator_index = attesting_index.get() # There has been no other valid attestation seen on an attestation subnet # that has an identical `attestation.data.target.epoch` and participating # validator index. # Slightly modified to allow only newer attestations than were previously # seen (no point in propagating older votes) if (pool.nextAttestationEpoch.lenu64 > validator_index.uint64) and pool.nextAttestationEpoch[validator_index].subnet > attestation.data.target.epoch: return errIgnore("Attestation: Validator has already voted in epoch") let pubkey = epochRef.validatorKey(validator_index) if pubkey.isNone(): # can't happen, in theory, because we checked the aggregator index above return errIgnore("Attestation: cannot find validator pubkey") # In the spec, is_valid_indexed_attestation is used to verify the signature - # here, we do a batch verification instead let sig = if checkSignature: # Attestation signatures are batch-verified let deferredCrypto = batchCrypto .scheduleAttestationCheck( fork, genesis_validators_root, attestation.data, pubkey.get(), attestation.signature) if deferredCrypto.isErr(): return checkedReject(deferredCrypto.error) let (cryptoFut, sig) = deferredCrypto.get() # Await the crypto check var x = (await cryptoFut) case x of BatchResult.Invalid: return checkedReject("Attestation: invalid signature") of BatchResult.Timeout: beacon_attestations_dropped_queue_full.inc() return errIgnore("Attestation: timeout checking signature") of BatchResult.Valid: sig # keep going only in this case else: let sig = attestation.signature.load() if not sig.isSome(): return checkedReject("Attestation: unable to load signature") sig.get() # Only valid attestations go in the list, which keeps validator_index # in range if not (pool.nextAttestationEpoch.lenu64 > validator_index.uint64): pool.nextAttestationEpoch.setLen(validator_index.int + 1) pool.nextAttestationEpoch[validator_index].subnet = attestation.data.target.epoch + 1 return ok((validator_index, sig)) # https://github.com/ethereum/consensus-specs/blob/v1.1.9/specs/phase0/p2p-interface.md#beacon_aggregate_and_proof proc validateAggregate*( pool: ref AttestationPool, batchCrypto: ref BatchCrypto, signedAggregateAndProof: SignedAggregateAndProof, wallTime: BeaconTime): Future[Result[ tuple[attestingIndices: seq[ValidatorIndex], sig: CookedSig], ValidationError]] {.async.} = # Some of the checks below have been reordered compared to the spec, to # perform the cheap checks first - in particular, we want to avoid loading # an `EpochRef` and checking signatures. This reordering might lead to # different IGNORE/REJECT results in turn affecting gossip scores. template aggregate_and_proof: untyped = signedAggregateAndProof.message template aggregate: untyped = aggregate_and_proof.aggregate # [REJECT] The aggregate attestation's epoch matches its target -- i.e. # `aggregate.data.target.epoch == compute_epoch_at_slot(aggregate.data.slot)` let slot = block: let v = check_attestation_slot_target(aggregate.data) if v.isErr(): return checkedReject(v.error) v.get() # [IGNORE] aggregate.data.slot is within the last # ATTESTATION_PROPAGATION_SLOT_RANGE slots (with a # MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance) -- i.e. aggregate.data.slot + # ATTESTATION_PROPAGATION_SLOT_RANGE >= current_slot >= aggregate.data.slot block: let v = check_propagation_slot_range(slot, wallTime) # [IGNORE] if v.isErr(): return err(v.error()) # [IGNORE] The aggregate is the first valid aggregate received for the # aggregator with index aggregate_and_proof.aggregator_index for the epoch # aggregate.data.target.epoch. # Slightly modified to allow only newer attestations than were previously # seen (no point in propagating older votes) if (pool.nextAttestationEpoch.lenu64 > aggregate_and_proof.aggregator_index) and pool.nextAttestationEpoch[ aggregate_and_proof.aggregator_index].aggregate > aggregate.data.target.epoch: return errIgnore("Aggregate: validator has already aggregated in epoch") # [REJECT] The attestation has participants -- that is, # len(get_attesting_indices(state, aggregate.data, aggregate.aggregation_bits)) >= 1. # # get_attesting_indices() is: # committee = get_beacon_committee(state, data.slot, data.index) # return set(index for i, index in enumerate(committee) if bits[i]) # # the attestation doesn't have participants is iff either: # (1) the aggregation bits are all 0; or # (2) the non-zero aggregation bits don't overlap with extant committee # members, i.e. they counts don't match. # But (2) would reflect an invalid aggregation in other ways, so reject it # either way. block: let v = check_aggregation_count(aggregate, singular = false) # [REJECT] if v.isErr(): return err(v.error) # [REJECT] The block being voted for (aggregate.data.beacon_block_root) # passes validation. # [IGNORE] if block is unseen so far and enqueue it in missing blocks let target = block: let v = check_beacon_and_target_block(pool[], aggregate.data) # [IGNORE/REJECT] if v.isErr(): return err(v.error) v.get() if pool[].covers(aggregate.data, aggregate.aggregation_bits): # https://github.com/ethereum/consensus-specs/issues/2183 - althoughh this # check was temporarily removed from the spec, the intent is to reinstate it # per discussion in the ticket. # # [IGNORE] The valid aggregate attestation defined by # `hash_tree_root(aggregate)` has _not_ already been seen # (via aggregate gossip, within a verified block, or through the creation of # an equivalent aggregate locally). # Our implementation of this check is slightly different in that it doesn't # consider aggregates from verified blocks - this would take a rather heavy # index to work correcly under fork conditions - we also check for coverage # of attestation bits instead of comparing with full root of aggreagte: # this captures the spirit of the checkk by ignoring aggregates that are # strict subsets of other, already-seen aggregates. return errIgnore("Aggregate already covered") let epochRef = block: let tmp = pool.dag.getEpochRef(target.blck, target.slot.epoch, false) if tmp.isErr: # shouldn't happen since we verified target warn "No EpochRef for attestation - report bug", aggregate = shortLog(aggregate), target = shortLog(target) return errIgnore("Aggregate: no EpochRef") tmp.get() # [REJECT] The committee index is within the expected range -- i.e. # data.index < get_committee_count_per_slot(state, data.target.epoch). let committee_index = block: let idx = epochRef.get_committee_index(aggregate.data.index) if idx.isErr(): return checkedReject("Attestation: committee index not within expected range") idx.get() # [REJECT] aggregate_and_proof.selection_proof selects the validator as an # aggregator for the slot -- i.e. is_aggregator(state, aggregate.data.slot, # aggregate.data.index, aggregate_and_proof.selection_proof) returns True. if not is_aggregator( epochRef, slot, committee_index, aggregate_and_proof.selection_proof): return checkedReject("Aggregate: incorrect aggregator") # [REJECT] The aggregator's validator index is within the committee -- i.e. # aggregate_and_proof.aggregator_index in get_beacon_committee(state, # aggregate.data.slot, aggregate.data.index). let aggregator_index = ValidatorIndex.init(aggregate_and_proof.aggregator_index).valueOr: return checkedReject("Aggregate: invalid aggregator index") if aggregator_index notin get_beacon_committee(epochRef, slot, committee_index): return checkedReject("Aggregate: aggregator's validator index not in committee") # 1. [REJECT] The aggregate_and_proof.selection_proof is a valid signature of the # aggregate.data.slot by the validator with index # aggregate_and_proof.aggregator_index. # get_slot_signature(state, aggregate.data.slot, privkey) # 2. [REJECT] The aggregator signature, signed_aggregate_and_proof.signature, is valid. # 3. [REJECT] The signature of aggregate is valid. let fork = pool.dag.forkAtEpoch(aggregate.data.slot.epoch) genesis_validators_root = getStateField(pool.dag.headState, genesis_validators_root) attesting_indices = get_attesting_indices( epochRef, slot, committee_index, aggregate.aggregation_bits) let deferredCrypto = batchCrypto .scheduleAggregateChecks( fork, genesis_validators_root, signedAggregateAndProof, epochRef, attesting_indices ) if deferredCrypto.isErr(): return checkedReject(deferredCrypto.error) let (aggregatorFut, slotFut, aggregateFut, sig) = deferredCrypto.get() block: # [REJECT] The aggregator signature, signed_aggregate_and_proof.signature, is valid. var x = await aggregatorFut case x of BatchResult.Invalid: return checkedReject("Aggregate: invalid aggregator signature") of BatchResult.Timeout: beacon_aggregates_dropped_queue_full.inc() return errIgnore("Aggregate: timeout checking aggregator signature") of BatchResult.Valid: discard block: # [REJECT] aggregate_and_proof.selection_proof var x = await slotFut case x of BatchResult.Invalid: return checkedReject("Aggregate: invalid slot signature") of BatchResult.Timeout: beacon_aggregates_dropped_queue_full.inc() return errIgnore("Aggregate: timeout checking slot signature") of BatchResult.Valid: discard block: # [REJECT] The aggregator signature, signed_aggregate_and_proof.signature, is valid. var x = await aggregateFut case x of BatchResult.Invalid: return checkedReject("Aggregate: invalid aggregate signature") of BatchResult.Timeout: beacon_aggregates_dropped_queue_full.inc() return errIgnore("Aggregate: timeout checking aggregate signature") of BatchResult.Valid: discard # The following rule follows implicitly from that we clear out any # unviable blocks from the chain dag: # # The current finalized_checkpoint is an ancestor of the block defined by # aggregate.data.beacon_block_root -- i.e. get_ancestor(store, # aggregate.data.beacon_block_root, # compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)) == # store.finalized_checkpoint.root # Only valid aggregates go in the list if pool.nextAttestationEpoch.lenu64 <= aggregate_and_proof.aggregator_index: pool.nextAttestationEpoch.setLen( aggregate_and_proof.aggregator_index.int + 1) pool.nextAttestationEpoch[aggregate_and_proof.aggregator_index].aggregate = aggregate.data.target.epoch + 1 return ok((attesting_indices, sig)) # https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/p2p-interface.md#attester_slashing proc validateAttesterSlashing*( pool: ExitPool, attester_slashing: AttesterSlashing): Result[void, ValidationError] = # [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 if pool.isSeen(attester_slashing): return errIgnore( "AttesterSlashing: attester-slashed index already attester-slashed") # [REJECT] All of the conditions within process_attester_slashing pass # validation. let attester_slashing_validity = check_attester_slashing(pool.dag.headState, attester_slashing, {}) if attester_slashing_validity.isErr: return err((ValidationResult.Reject, attester_slashing_validity.error)) ok() # https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/p2p-interface.md#proposer_slashing proc validateProposerSlashing*( pool: ExitPool, proposer_slashing: ProposerSlashing): Result[void, ValidationError] = # Not from spec; the rest of NBC wouldn't have correctly processed it either. if proposer_slashing.signed_header_1.message.proposer_index > high(int).uint64: return errIgnore("ProposerSlashing: proposer-slashed index too high") # [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 pool.isSeen(proposer_slashing): return errIgnore( "ProposerSlashing: proposer-slashed index already proposer-slashed") # [REJECT] All of the conditions within process_proposer_slashing pass validation. let proposer_slashing_validity = check_proposer_slashing(pool.dag.headState, proposer_slashing, {}) if proposer_slashing_validity.isErr: return err((ValidationResult.Reject, proposer_slashing_validity.error)) ok() # https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/phase0/p2p-interface.md#voluntary_exit proc validateVoluntaryExit*( pool: ExitPool, signed_voluntary_exit: SignedVoluntaryExit): Result[void, ValidationError] = # [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 >= getStateField(pool.dag.headState, validators).lenu64: return errIgnore("VoluntaryExit: validator index too high") # Given that getStateField(pool.dag.headState, validators) is a seq, # signed_voluntary_exit.message.validator_index.int is already valid, but # check explicitly if one changes that data structure. if pool.isSeen(signed_voluntary_exit): return errIgnore("VoluntaryExit: validator index already voluntarily exited") # [REJECT] All of the conditions within process_voluntary_exit pass # validation. let voluntary_exit_validity = check_voluntary_exit( pool.dag.cfg, pool.dag.headState, signed_voluntary_exit, {}) if voluntary_exit_validity.isErr: return err((ValidationResult.Reject, voluntary_exit_validity.error)) # Send notification about new voluntary exit via callback if not(isNil(pool.onVoluntaryExitReceived)): pool.onVoluntaryExitReceived(signed_voluntary_exit) ok() # https://github.com/ethereum/consensus-specs/blob/v1.2.0-rc.1/specs/altair/p2p-interface.md#sync_committee_subnet_id proc validateSyncCommitteeMessage*( dag: ChainDAGRef, batchCrypto: ref BatchCrypto, syncCommitteeMsgPool: ref SyncCommitteeMsgPool, msg: SyncCommitteeMessage, subcommitteeIdx: SyncSubcommitteeIndex, wallTime: BeaconTime, checkSignature: bool): Future[Result[(seq[uint64], CookedSig), ValidationError]] {.async.} = block: # [IGNORE] The message's slot is for the current slot (with a # `MAXIMUM_GOSSIP_CLOCK_DISPARITY` allowance), i.e. # `sync_committee_message.slot == current_slot`. let v = check_propagation_slot_range(msg.slot, wallTime) if v.isErr(): return err(v.error()) # [REJECT] The subnet_id is valid for the given validator # i.e. subnet_id in compute_subnets_for_sync_committee(state, sync_committee_message.validator_index). # Note this validation implies the validator is part of the broader # current sync committee along with the correct subcommittee. # This check also ensures that the validator index is in range let positionsInSubcommittee = dag.getSubcommitteePositions( msg.slot + 1, subcommitteeIdx, msg.validator_index) if positionsInSubcommittee.len == 0: return errReject( "SyncCommitteeMessage: originator not part of sync committee") block: # [IGNORE] There has been no other valid sync committee message for the # declared `slot` for the validator referenced by # `sync_committee_message.validator_index` # # Note this validation is per topic so that for a given slot, multiple # messages could be forwarded with the same validator_index as long as # the subnet_ids are distinct. if syncCommitteeMsgPool[].isSeen(msg, subcommitteeIdx): return errIgnore("SyncCommitteeMessage: duplicate message") # [REJECT] The signature is valid for the message beacon_block_root for the # validator referenced by validator_index. let epoch = msg.slot.epoch fork = dag.forkAtEpoch(epoch) genesis_validators_root = dag.genesis_validators_root senderPubKey = dag.validatorKey(msg.validator_index) if senderPubKey.isNone(): return errReject("SyncCommitteeMessage: invalid validator index") let sig = if checkSignature: # Attestation signatures are batch-verified let deferredCrypto = batchCrypto .scheduleSyncCommitteeMessageCheck( fork, genesis_validators_root, msg.slot, msg.beacon_block_root, senderPubKey.get(), msg.signature) if deferredCrypto.isErr(): return errReject(deferredCrypto.error) # Await the crypto check let (cryptoFut, sig) = deferredCrypto.get() var x = (await cryptoFut) case x of BatchResult.Invalid: return errReject("SyncCommitteeMessage: invalid signature") of BatchResult.Timeout: beacon_sync_messages_dropped_queue_full.inc() return errIgnore("SyncCommitteeMessage: timeout checking signature") of BatchResult.Valid: sig # keep going only in this case else: let sig = msg.signature.load() if not sig.isSome(): return errReject("SyncCommitteeMessage: unable to load signature") sig.get() return ok((positionsInSubcommittee, sig)) # https://github.com/ethereum/consensus-specs/blob/v1.1.10/specs/altair/p2p-interface.md#sync_committee_contribution_and_proof proc validateContribution*( dag: ChainDAGRef, batchCrypto: ref BatchCrypto, syncCommitteeMsgPool: ref SyncCommitteeMsgPool, msg: SignedContributionAndProof, wallTime: BeaconTime, checkSignature: bool): Future[Result[(CookedSig, seq[ValidatorIndex]), ValidationError]] {.async.} = let syncCommitteeSlot = msg.message.contribution.slot # [IGNORE] The contribution's slot is for the current slot # (with a MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance) # i.e. contribution.slot == current_slot. block: let v = check_propagation_slot_range(syncCommitteeSlot, wallTime) # [IGNORE] if v.isErr(): return err(v.error()) # [REJECT] The subcommittee index is in the allowed range # i.e. contribution.subcommittee_index < SYNC_COMMITTEE_SUBNET_COUNT. let subcommitteeIdx = block: let v = SyncSubcommitteeIndex.init(msg.message.contribution.subcommittee_index) if v.isErr(): return errReject("SignedContributionAndProof: subcommittee index too high") v.get() # [REJECT] contribution_and_proof.selection_proof selects the validator as an aggregator for the slot # i.e. is_sync_committee_aggregator(contribution_and_proof.selection_proof) returns True. if not is_sync_committee_aggregator(msg.message.selection_proof): return errReject("SignedContributionAndProof: invalid selection_proof") # [IGNORE] The sync committee contribution is the first valid contribution # received for the aggregator with index contribution_and_proof.aggregator_index # for the slot contribution.slot and subcommittee index contribution.subcommittee_index # (this requires maintaining a cache of size SYNC_COMMITTEE_SIZE for this # topic that can be flushed after each slot). if syncCommitteeMsgPool[].isSeen(msg.message): return errIgnore("SignedContributionAndProof: duplicate contribution") # [REJECT] The aggregator's validator index is in the declared subcommittee # of the current sync committee. # i.e. state.validators[contribution_and_proof.aggregator_index].pubkey in # get_sync_subcommittee_pubkeys(state, contribution.subcommittee_index). let epoch = msg.message.contribution.slot.epoch fork = dag.forkAtEpoch(epoch) genesis_validators_root = dag.genesis_validators_root if msg.message.contribution.aggregation_bits.countOnes() == 0: # [REJECT] The contribution has participants # that is, any(contribution.aggregation_bits). return errReject("SignedContributionAndProof: aggregation bits empty") # TODO we take a copy of the participants to avoid the data going stale # between validation and use - nonetheless, a design that avoids it and # stays safe would be nice let participants = dag.syncCommitteeParticipants( msg.message.contribution.slot, subcommitteeIdx) let sig = if checkSignature: let deferredCrypto = batchCrypto.scheduleContributionChecks( fork, genesis_validators_root, msg, subcommitteeIdx, dag) if deferredCrypto.isErr(): return errReject(deferredCrypto.error) let (aggregatorFut, proofFut, contributionFut, sig) = deferredCrypto.get() block: # [REJECT] The aggregator signature, signed_contribution_and_proof.signature, is valid var x = await aggregatorFut case x of BatchResult.Invalid: return errReject("SignedContributionAndProof: invalid aggregator signature") of BatchResult.Timeout: beacon_contributions_dropped_queue_full.inc() return errIgnore("SignedContributionAndProof: timeout checking aggregator signature") of BatchResult.Valid: discard block: var x = await proofFut case x of BatchResult.Invalid: return errReject("SignedContributionAndProof: invalid proof") of BatchResult.Timeout: beacon_contributions_dropped_queue_full.inc() return errIgnore("SignedContributionAndProof: timeout checking proof") of BatchResult.Valid: discard block: # [REJECT] The aggregator signature, signed_aggregate_and_proof.signature, is valid. var x = await contributionFut case x of BatchResult.Invalid: return errReject("SignedContributionAndProof: invalid contribution signature") of BatchResult.Timeout: beacon_contributions_dropped_queue_full.inc() return errIgnore("SignedContributionAndProof: timeout checking contribution signature") of BatchResult.Valid: discard sig else: let sig = msg.message.contribution.signature.load() if not sig.isSome(): return errReject("SyncCommitteeMessage: unable to load signature") sig.get() return ok((sig, participants)) # https://github.com/ethereum/consensus-specs/blob/vFuture/specs/altair/sync-protocol.md#light_client_finality_update proc validateLightClientFinalityUpdate*( pool: var LightClientPool, dag: ChainDAGRef, finality_update: altair.LightClientFinalityUpdate, wallTime: BeaconTime): Result[void, ValidationError] = let finalized_slot = finality_update.finalized_header.slot if finalized_slot <= pool.latestForwardedFinalitySlot: # [IGNORE] No other `finality_update` with a lower or equal # `finalized_header.slot` was already forwarded on the network. return errIgnore("LightClientFinalityUpdate: slot already forwarded") let signature_slot = finality_update.signature_slot currentTime = wallTime + MAXIMUM_GOSSIP_CLOCK_DISPARITY forwardTime = signature_slot.light_client_finality_update_time if currentTime < forwardTime: # [IGNORE] The `finality_update` is received after the block at # `signature_slot` was given enough time to propagate through the network. return errIgnore("LightClientFinalityUpdate: received too early") if finality_update != dag.lcDataStore.cache.latest: # [IGNORE] The received `finality_update` matches the locally computed one # exactly. return errIgnore("LightClientFinalityUpdate: not matching local") pool.latestForwardedFinalitySlot = finalized_slot ok() # https://github.com/ethereum/consensus-specs/blob/vFuture/specs/altair/sync-protocol.md#light_client_optimistic_update proc validateLightClientOptimisticUpdate*( pool: var LightClientPool, dag: ChainDAGRef, optimistic_update: altair.LightClientOptimisticUpdate, wallTime: BeaconTime): Result[void, ValidationError] = let attested_slot = optimistic_update.attested_header.slot if attested_slot <= pool.latestForwardedOptimisticSlot: # [IGNORE] No other `optimistic_update` with a lower or equal # `attested_header.slot` was already forwarded on the network. return errIgnore("LightClientOptimisticUpdate: slot already forwarded") let signature_slot = optimistic_update.signature_slot currentTime = wallTime + MAXIMUM_GOSSIP_CLOCK_DISPARITY forwardTime = signature_slot.light_client_optimistic_update_time if currentTime < forwardTime: # [IGNORE] The `optimistic_update` is received after the block at # `signature_slot` was given enough time to propagate through the network. return errIgnore("LightClientOptimisticUpdate: received too early") if not optimistic_update.matches(dag.lcDataStore.cache.latest): # [IGNORE] The received `optimistic_update` matches the locally computed one # exactly. return errIgnore("LightClientOptimisticUpdate: not matching local") pool.latestForwardedOptimisticSlot = attested_slot ok()