348 lines
13 KiB
Nim
348 lines
13 KiB
Nim
import
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deques, options, sequtils, tables,
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chronicles,
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./spec/[beaconstate, bitfield, datatypes, crypto, digest, helpers, validator],
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./extras, ./beacon_chain_db, ./ssz, ./block_pool,
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beacon_node_types
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proc init*(T: type AttestationPool, blockPool: BlockPool): T =
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T(
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slots: initDeque[SlotData](),
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blockPool: blockPool,
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unresolved: initTable[Eth2Digest, UnresolvedAttestation](),
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latestAttestations: initTable[ValidatorPubKey, BlockRef]()
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)
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proc combine*(tgt: var Attestation, src: Attestation, flags: UpdateFlags) =
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## Combine the signature and participation bitfield, with the assumption that
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## the same data is being signed - if the signatures overlap, they are not
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## combined.
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doAssert tgt.data == src.data
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# In a BLS aggregate signature, one needs to count how many times a
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# particular public key has been added - since we use a single bit per key, we
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# can only it once, thus we can never combine signatures that overlap already!
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if not tgt.aggregation_bits.overlaps(src.aggregation_bits):
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tgt.aggregation_bits.combine(src.aggregation_bits)
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if skipValidation notin flags:
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tgt.signature.combine(src.signature)
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proc validate(
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state: BeaconState, attestation: Attestation, flags: UpdateFlags): bool =
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# TODO these validations should probably be done elsewhere, and really bad
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# attestations should probably cause some sort of feedback to the network
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# layer so they don't spread further.. is there a sliding scale here of
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# badness?
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# TODO half of this stuff is from beaconstate.validateAttestation - merge?
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let attestationSlot = get_attestation_data_slot(state, attestation.data)
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if attestationSlot < state.finalized_epoch.compute_start_slot_of_epoch():
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debug "Old attestation",
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attestationSlot = humaneSlotNum(attestationSlot),
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attestationEpoch = humaneEpochNum(attestationSlot.compute_epoch_of_slot),
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stateSlot = humaneSlotNum(state.slot),
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finalizedEpoch = humaneEpochNum(state.finalized_epoch)
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return
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# TODO what makes sense here? If an attestation is from the future with
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# regards to the state, something is wrong - it's a bad attestation, we're
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# desperatly behind or someone is sending bogus attestations...
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if attestationSlot > state.slot + 64:
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debug "Future attestation",
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attestationSlot = humaneSlotNum(attestationSlot),
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attestationEpoch = humaneEpochNum(attestationSlot.compute_epoch_of_slot),
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stateSlot = humaneSlotNum(state.slot),
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finalizedEpoch = humaneEpochNum(state.finalized_epoch)
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return
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if not allIt(attestation.custody_bits.bits, it == 0):
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notice "Invalid custody bitfield for phase 0"
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return false
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if not anyIt(attestation.aggregation_bits.bits, it != 0):
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notice "Empty aggregation bitfield"
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return false
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## the rest; turns into expensive NOP until then.
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if skipValidation notin flags:
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let
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participants = get_attesting_indices_seq(
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state, attestation.data, attestation.aggregation_bits)
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## TODO when the custody_bits assertion-to-emptiness disappears do this
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## and fix the custody_bit_0_participants check to depend on it.
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# custody_bit_1_participants = {nothing, always, because assertion above}
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custody_bit_1_participants: seq[ValidatorIndex] = @[]
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custody_bit_0_participants = participants
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group_public_key = bls_aggregate_pubkeys(
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participants.mapIt(state.validators[it].pubkey))
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# Verify that aggregate_signature verifies using the group pubkey.
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if not bls_verify_multiple(
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@[
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bls_aggregate_pubkeys(mapIt(custody_bit_0_participants,
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state.validators[it].pubkey)),
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bls_aggregate_pubkeys(mapIt(custody_bit_1_participants,
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state.validators[it].pubkey)),
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],
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@[
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hash_tree_root(AttestationDataAndCustodyBit(
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data: attestation.data, custody_bit: false)),
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hash_tree_root(AttestationDataAndCustodyBit(
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data: attestation.data, custody_bit: true)),
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],
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attestation.signature,
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get_domain(state, DOMAIN_ATTESTATION,
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compute_epoch_of_slot(get_attestation_data_slot(state, attestation.data))),
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):
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notice "Invalid signature", participants
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return false
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true
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proc slotIndex(
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pool: var AttestationPool, state: BeaconState, attestationSlot: Slot): int =
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## Grow and garbage collect pool, returning the deque index of the slot
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# We keep a sliding window of attestations, roughly from the last finalized
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# epoch to now, because these are the attestations that may affect the voting
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# outcome. Some of these attestations will already have been added to blocks,
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# while others are fresh off the network.
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# TODO only the latest vote of each validator counts. Can we use that somehow?
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doAssert attestationSlot >= pool.startingSlot,
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"""
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We should have checked in validate that attestation is newer than
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finalized_slot and we never prune things before that, per below condition!
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""" &
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", attestationSlot: " & $humaneSlotNum(attestationSlot) &
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", startingSlot: " & $humaneSlotNum(pool.startingSlot)
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if pool.slots.len == 0:
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# Because the first attestations may arrive in any order, we'll make sure
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# to start counting at the last finalized epoch start slot - anything
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# earlier than that is thrown out by the above check
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info "First attestation!",
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attestationSlot = $humaneSlotNum(attestationSlot)
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pool.startingSlot = state.finalized_epoch.compute_start_slot_of_epoch()
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if pool.startingSlot + pool.slots.len.uint64 <= attestationSlot:
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debug "Growing attestation pool",
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attestationSlot = $humaneSlotNum(attestationSlot),
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startingSlot = $humaneSlotNum(pool.startingSlot)
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# Make sure there's a pool entry for every slot, even when there's a gap
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while pool.startingSlot + pool.slots.len.uint64 <= attestationSlot:
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pool.slots.addLast(SlotData())
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if pool.startingSlot < state.finalized_epoch.compute_start_slot_of_epoch():
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debug "Pruning attestation pool",
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startingSlot = $humaneSlotNum(pool.startingSlot),
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finalizedSlot =
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$humaneSlotNum(state.finalized_epoch.compute_start_slot_of_epoch())
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# TODO there should be a better way to remove a whole epoch of stuff..
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while pool.startingSlot < state.finalized_epoch.compute_start_slot_of_epoch():
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pool.slots.popFirst()
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pool.startingSlot += 1
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int(attestationSlot - pool.startingSlot)
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proc updateLatestVotes(
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pool: var AttestationPool, state: BeaconState, attestationSlot: Slot,
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participants: seq[ValidatorIndex], blck: BlockRef) =
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for validator in participants:
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let
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pubKey = state.validators[validator].pubkey
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current = pool.latestAttestations.getOrDefault(pubKey)
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if current.isNil or current.slot < attestationSlot:
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pool.latestAttestations[pubKey] = blck
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proc add*(pool: var AttestationPool,
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state: BeaconState,
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attestation: Attestation) =
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# TODO should validate against the state of the block being attested to?
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if not validate(state, attestation, {skipValidation}):
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return
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# TODO inefficient data structures..
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let
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attestationSlot = get_attestation_data_slot(state, attestation.data)
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idx = pool.slotIndex(state, attestationSlot)
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slotData = addr pool.slots[idx]
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validation = Validation(
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aggregation_bits: attestation.aggregation_bits,
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custody_bits: attestation.custody_bits,
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aggregate_signature: attestation.signature)
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participants = get_attesting_indices_seq(
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state, attestation.data, validation.aggregation_bits)
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var found = false
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for a in slotData.attestations.mitems():
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if a.data == attestation.data:
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for v in a.validations:
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if validation.aggregation_bits.isSubsetOf(v.aggregation_bits):
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# The validations in the new attestation are a subset of one of the
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# attestations that we already have on file - no need to add this
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# attestation to the database
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# TODO what if the new attestation is useful for creating bigger
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# sets by virtue of not overlapping with some other attestation
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# and therefore being useful after all?
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debug "Ignoring subset attestation",
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existingParticipants = get_attesting_indices_seq(
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state, a.data, v.aggregation_bits),
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newParticipants = participants
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found = true
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break
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if not found:
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# Attestations in the pool that are a subset of the new attestation
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# can now be removed per same logic as above
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a.validations.keepItIf(
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if it.aggregation_bits.isSubsetOf(
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validation.aggregation_bits):
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debug "Removing subset attestation",
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existingParticipants = get_attesting_indices_seq(
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state, a.data, it.aggregation_bits),
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newParticipants = participants
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false
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else:
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true)
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a.validations.add(validation)
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pool.updateLatestVotes(state, attestationSlot, participants, a.blck)
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info "Attestation resolved",
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attestationData = shortLog(attestation.data),
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validations = a.validations.len()
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found = true
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break
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if not found:
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if (let blck = pool.blockPool.getOrResolve(
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attestation.data.beacon_block_root); blck != nil):
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slotData.attestations.add(AttestationEntry(
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data: attestation.data,
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blck: blck,
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validations: @[validation]
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))
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pool.updateLatestVotes(state, attestationSlot, participants, blck)
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info "Attestation resolved",
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attestationData = shortLog(attestation.data),
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validations = 1
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else:
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pool.unresolved[attestation.data.beacon_block_root] =
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UnresolvedAttestation(
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attestation: attestation,
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)
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proc getAttestationsForBlock*(
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pool: AttestationPool, state: BeaconState,
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newBlockSlot: Slot): seq[Attestation] =
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if newBlockSlot - GENESIS_SLOT < MIN_ATTESTATION_INCLUSION_DELAY:
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debug "Too early for attestations",
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newBlockSlot = humaneSlotNum(newBlockSlot)
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return
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if pool.slots.len == 0: # startingSlot not set yet!
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info "No attestations found (pool empty)",
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newBlockSlot = humaneSlotNum(newBlockSlot)
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return
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var cache = get_empty_per_epoch_cache()
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let
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# TODO in theory we could include attestations from other slots also, but
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# we're currently not tracking which attestations have already been included
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# in blocks on the fork we're aiming for.. this is a conservative approach
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# that's guaranteed to not include any duplicates, because it's the first
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# time the attestations are up for inclusion!
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attestationSlot = newBlockSlot - MIN_ATTESTATION_INCLUSION_DELAY
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if attestationSlot < pool.startingSlot or
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attestationSlot >= pool.startingSlot + pool.slots.len.uint64:
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info "No attestations",
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attestationSlot = humaneSlotNum(attestationSlot),
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startingSlot = humaneSlotNum(pool.startingSlot),
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endingSlot = humaneSlotNum(pool.startingSlot + pool.slots.len.uint64)
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return
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let
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slotDequeIdx = int(attestationSlot - pool.startingSlot)
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slotData = pool.slots[slotDequeIdx]
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for a in slotData.attestations:
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var
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attestation = Attestation(
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aggregation_bits: a.validations[0].aggregation_bits,
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data: a.data,
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custody_bits: a.validations[0].custody_bits,
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signature: a.validations[0].aggregate_signature
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)
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# TODO what's going on here is that when producing a block, we need to
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# include only such attestations that will not cause block validation
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# to fail. How this interacts with voting and the acceptance of
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# attestations into the pool in general is an open question that needs
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# revisiting - for example, when attestations are added, against which
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# state should they be validated, if at all?
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if not process_attestation(
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state, attestation, {skipValidation, nextSlot}, cache):
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continue
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for v in a.validations[1..^1]:
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# TODO We need to select a set of attestations that maximise profit by
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# adding the largest combined attestation set that we can find - this
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# unfortunately looks an awful lot like
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# https://en.wikipedia.org/wiki/Set_packing - here we just iterate
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# and naively add as much as possible in one go, by we could also
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# add the same attestation data twice, as long as there's at least
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# one new attestation in there
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if not attestation.aggregation_bits.overlaps(
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v.aggregation_bits):
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attestation.aggregation_bits.combine(
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v.aggregation_bits)
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attestation.custody_bits.combine(v.custody_bits)
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attestation.signature.combine(v.aggregate_signature)
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result.add(attestation)
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if result.len >= MAX_ATTESTATIONS:
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return
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proc resolve*(pool: var AttestationPool, state: BeaconState) =
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var done: seq[Eth2Digest]
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var resolved: seq[Attestation]
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for k, v in pool.unresolved.mpairs():
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let attestation_slot = get_attestation_data_slot(state, v.attestation.data)
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if v.tries > 8 or attestation_slot < pool.startingSlot:
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done.add(k)
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else:
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if pool.blockPool.get(k).isSome():
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resolved.add(v.attestation)
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done.add(k)
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else:
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inc v.tries
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for k in done:
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pool.unresolved.del(k)
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for a in resolved:
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pool.add(state, a)
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proc latestAttestation*(
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pool: AttestationPool, pubKey: ValidatorPubKey): BlockRef =
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pool.latestAttestations.getOrDefault(pubKey)
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