572 lines
22 KiB
Nim
572 lines
22 KiB
Nim
# beacon_chain
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# Copyright (c) 2022-2023 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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{.push raises: [].}
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import
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chronos, metrics,
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../spec/light_client_sync,
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../consensus_object_pools/block_pools_types,
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".."/[beacon_clock, sszdump],
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"."/[eth2_processor, gossip_validation]
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export sszdump, eth2_processor, gossip_validation
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logScope: topics = "gossip_lc"
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# Light Client Processor
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# ------------------------------------------------------------------------------
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# The light client processor handles received light client objects
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declareHistogram light_client_store_object_duration_seconds,
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"storeObject() duration", buckets = [0.25, 0.5, 1, 2, 4, 8, Inf]
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type
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Nothing = object
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GetTrustedBlockRootCallback* =
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proc(): Option[Eth2Digest] {.gcsafe, raises: [Defect].}
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VoidCallback* =
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proc() {.gcsafe, raises: [Defect].}
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ValueObserver[V] =
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proc(v: V) {.gcsafe, raises: [Defect].}
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BootstrapObserver* =
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ValueObserver[ForkedLightClientBootstrap]
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UpdateObserver* =
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ValueObserver[ForkedLightClientUpdate]
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FinalityUpdateObserver* =
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ValueObserver[ForkedLightClientFinalityUpdate]
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OptimisticUpdateObserver* =
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ValueObserver[ForkedLightClientOptimisticUpdate]
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LightClientFinalizationMode* {.pure.} = enum
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Strict
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## Only finalize light client data that:
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## - has been signed by a supermajority (2/3) of the sync committee
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## - has a valid finality proof
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##
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## Optimizes for security, but may become stuck if there is any of:
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## - non-finality for an entire sync committee period
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## - low sync committee participation for an entire sync committee period
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## Such periods need to be covered by an out-of-band syncing mechanism.
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##
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## Note that a compromised supermajority of the sync committee is able to
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## sign arbitrary light client data, even after being slashed. The light
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## client cannot validate the slashing status of sync committee members.
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## Likewise, voluntarily exited validators may sign bad light client data
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## for the sync committee periods in which they used to be selected.
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Optimistic
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## Attempt to finalize light client data not satisfying strict conditions
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## if there is no progress for an extended period of time and if there are
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## repeated messages indicating that it is the best available data on the
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## network for the affected time period.
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##
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## Optimizes for availability of recent data, but may end up on incorrect
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## forks if run in a hostile network environment (no honest peers), or if
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## the low sync committee participation is being exploited by bad actors.
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LightClientProcessor* = object
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## This manages the processing of received light client objects
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##
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## from:
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## - Gossip:
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## - `LightClientFinalityUpdate`
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## - `LightClientOptimisticUpdate`
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## - `LightClientManager`:
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## - `GetLightClientBootstrap`
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## - `LightClientUpdatesByRange`
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## - `GetLightClientFinalityUpdate`
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## - `GetLightClientOptimisticUpdate`
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##
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## are then verified and added to:
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## - `LightClientStore`
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# Config
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# ----------------------------------------------------------------
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dumpEnabled: bool
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dumpDirInvalid: string
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dumpDirIncoming: string
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strictVerification: bool
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# Consumer
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# ----------------------------------------------------------------
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store: ref ForkedLightClientStore
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getBeaconTime: GetBeaconTimeFn
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getTrustedBlockRoot: GetTrustedBlockRootCallback
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onStoreInitialized, onFinalizedHeader, onOptimisticHeader: VoidCallback
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bootstrapObserver: BootstrapObserver
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updateObserver: UpdateObserver
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finalityUpdateObserver: FinalityUpdateObserver
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optimisticUpdateObserver: OptimisticUpdateObserver
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cfg: RuntimeConfig
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genesis_validators_root: Eth2Digest
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case finalizationMode: LightClientFinalizationMode
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of LightClientFinalizationMode.Strict:
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discard
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of LightClientFinalizationMode.Optimistic:
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lastProgressTick: BeaconTime # Moment when last update made progress
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lastDuplicateTick: BeaconTime # Moment when last duplicate update received
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numDupsSinceProgress: int # Number of duplicates since last progress
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latestFinalityUpdate: ForkedLightClientOptimisticUpdate
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const
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# These constants have been chosen empirically and are not backed by spec
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duplicateRateLimit = chronos.seconds(5) # Rate limit for counting duplicates
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duplicateCountDelay = chronos.minutes(15) # Delay to start counting duplicates
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minForceUpdateDelay = chronos.minutes(30) # Minimum delay until forced-update
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minForceUpdateDuplicates = 100 # Minimum duplicates until forced-update
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# Initialization
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# ------------------------------------------------------------------------------
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proc new*(
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T: type LightClientProcessor,
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dumpEnabled: bool,
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dumpDirInvalid, dumpDirIncoming: string,
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cfg: RuntimeConfig,
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genesis_validators_root: Eth2Digest,
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finalizationMode: LightClientFinalizationMode,
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store: ref ForkedLightClientStore,
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getBeaconTime: GetBeaconTimeFn,
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getTrustedBlockRoot: GetTrustedBlockRootCallback,
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onStoreInitialized: VoidCallback = nil,
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onFinalizedHeader: VoidCallback = nil,
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onOptimisticHeader: VoidCallback = nil,
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bootstrapObserver: BootstrapObserver = nil,
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updateObserver: UpdateObserver = nil,
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finalityUpdateObserver: FinalityUpdateObserver = nil,
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optimisticUpdateObserver: OptimisticUpdateObserver = nil,
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strictVerification = false
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): ref LightClientProcessor =
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(ref LightClientProcessor)(
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dumpEnabled: dumpEnabled,
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dumpDirInvalid: dumpDirInvalid,
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dumpDirIncoming: dumpDirIncoming,
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strictVerification: strictVerification,
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store: store,
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getBeaconTime: getBeaconTime,
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getTrustedBlockRoot: getTrustedBlockRoot,
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onStoreInitialized: onStoreInitialized,
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onFinalizedHeader: onFinalizedHeader,
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onOptimisticHeader: onOptimisticHeader,
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bootstrapObserver: bootstrapObserver,
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updateObserver: updateObserver,
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finalityUpdateObserver: finalityUpdateObserver,
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optimisticUpdateObserver: optimisticUpdateObserver,
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cfg: cfg,
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genesis_validators_root: genesis_validators_root,
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finalizationMode: finalizationMode)
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# Storage
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# ------------------------------------------------------------------------------
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proc dumpInvalidObject(
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self: LightClientProcessor,
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obj: SomeForkyLightClientObject) =
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if self.dumpEnabled:
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dump(self.dumpDirInvalid, obj)
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proc dumpObject[T](
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self: LightClientProcessor,
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obj: SomeForkyLightClientObject,
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res: Result[T, VerifierError]) =
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if self.dumpEnabled and res.isErr:
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case res.error
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of VerifierError.Invalid:
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self.dumpInvalidObject(obj)
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of VerifierError.MissingParent:
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dump(self.dumpDirIncoming, obj)
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else:
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discard
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proc tryForceUpdate(
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self: var LightClientProcessor,
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wallTime: BeaconTime) =
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## Try to force-update to the next sync committee period.
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let wallSlot = wallTime.slotOrZero()
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doAssert self.finalizationMode == LightClientFinalizationMode.Optimistic
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withForkyStore(self.store[]):
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when lcDataFork > LightClientDataFork.None:
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case forkyStore.process_light_client_store_force_update(wallSlot)
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of NoUpdate:
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discard
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of DidUpdateWithoutSupermajority:
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warn "Light client force-updated without supermajority",
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finalizedSlot = forkyStore.finalized_header.beacon.slot,
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optimisticSlot = forkyStore.optimistic_header.beacon.slot
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of DidUpdateWithoutFinality:
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warn "Light client force-updated without finality proof",
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finalizedSlot = forkyStore.finalized_header.beacon.slot,
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optimisticSlot = forkyStore.optimistic_header.beacon.slot
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proc processObject(
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self: var LightClientProcessor,
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obj: SomeForkedLightClientObject,
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wallTime: BeaconTime): Result[void, VerifierError] =
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let
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wallSlot = wallTime.slotOrZero()
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res = withForkyObject(obj):
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when lcDataFork > LightClientDataFork.None:
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when forkyObject is ForkyLightClientBootstrap:
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if self.store[].kind > LightClientDataFork.None:
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err(VerifierError.Duplicate)
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else:
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let trustedBlockRoot = self.getTrustedBlockRoot()
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if trustedBlockRoot.isNone:
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err(VerifierError.MissingParent)
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else:
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let initRes = initialize_light_client_store(
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trustedBlockRoot.get, forkyObject, self.cfg)
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if initRes.isErr:
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err(initRes.error)
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else:
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self.store[] = ForkedLightClientStore(kind: lcDataFork)
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self.store[].forky(lcDataFork) = initRes.get
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ok()
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elif forkyObject is SomeForkyLightClientUpdate:
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if self.store[].kind == LightClientDataFork.None:
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err(VerifierError.MissingParent)
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else:
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if lcDataFork > self.store[].kind:
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info "Upgrading light client",
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oldFork = self.store[].kind, newFork = lcDataFork
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self.store[].migrateToDataFork(lcDataFork)
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withForkyStore(self.store[]):
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when lcDataFork > LightClientDataFork.None:
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let upgradedObject = obj.migratingToDataFork(lcDataFork)
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process_light_client_update(
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forkyStore, upgradedObject.forky(lcDataFork), wallSlot,
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self.cfg, self.genesis_validators_root)
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else: raiseAssert "Unreachable"
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else:
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err(VerifierError.Invalid)
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withForkyObject(obj):
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when lcDataFork > LightClientDataFork.None:
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self.dumpObject(forkyObject, res)
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if res.isErr:
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when obj is ForkedLightClientUpdate:
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if self.finalizationMode == LightClientFinalizationMode.Optimistic and
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obj.kind <= self.store[].kind:
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withForkyStore(self.store[]):
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when lcDataFork > LightClientDataFork.None:
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if forkyStore.best_valid_update.isSome:
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# `best_valid_update` is set when supermajority / finality proof
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# is unavailable. In that case, we will wait for a better update.
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# If none is made available within reasonable time, light client
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# is force-updated with best known data to ensure sync progress.
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case res.error
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of VerifierError.Duplicate:
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if wallTime >= self.lastDuplicateTick + duplicateRateLimit:
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if self.numDupsSinceProgress < minForceUpdateDuplicates:
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let upgradedObj = obj.migratingToDataFork(lcDataFork)
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if upgradedObj.forky(lcDataFork).matches(
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forkyStore.best_valid_update.get):
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self.lastDuplicateTick = wallTime
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inc self.numDupsSinceProgress
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if self.numDupsSinceProgress >= minForceUpdateDuplicates and
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wallTime >= self.lastProgressTick + minForceUpdateDelay:
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self.tryForceUpdate(wallTime)
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self.lastProgressTick = wallTime
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self.lastDuplicateTick = wallTime + duplicateCountDelay
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self.numDupsSinceProgress = 0
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else: discard
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return res
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when obj is ForkedLightClientBootstrap | ForkedLightClientUpdate:
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if self.finalizationMode == LightClientFinalizationMode.Optimistic:
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self.lastProgressTick = wallTime
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self.lastDuplicateTick = wallTime + duplicateCountDelay
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self.numDupsSinceProgress = 0
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res
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template withReportedProgress(
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obj: SomeForkedLightClientObject | Nothing, body: untyped): bool =
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block:
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let
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oldIsInitialized = self.store[].kind > LightClientDataFork.None
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oldNextCommitteeKnown = withForkyStore(self.store[]):
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when lcDataFork > LightClientDataFork.None:
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forkyStore.is_next_sync_committee_known
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else:
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false
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var
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oldFinalized = withForkyStore(self.store[]):
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when lcDataFork > LightClientDataFork.None:
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var header = ForkedLightClientHeader(kind: lcDataFork)
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header.forky(lcDataFork) = forkyStore.finalized_header
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header
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else:
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default(ForkedLightClientHeader)
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oldOptimistic = withForkyStore(self.store[]):
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when lcDataFork > LightClientDataFork.None:
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var header = ForkedLightClientHeader(kind: lcDataFork)
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header.forky(lcDataFork) = forkyStore.optimistic_header
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header
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else:
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default(ForkedLightClientHeader)
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body
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var
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didProgress = false
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didSignificantProgress = false
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let newIsInitialized = self.store[].kind > LightClientDataFork.None
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if newIsInitialized > oldIsInitialized:
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didProgress = true
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didSignificantProgress = true
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if self.onStoreInitialized != nil:
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self.onStoreInitialized()
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self.onStoreInitialized = nil
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withForkyStore(self.store[]):
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when lcDataFork > LightClientDataFork.None:
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if oldOptimistic.kind <= lcDataFork:
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oldOptimistic.migrateToDataFork(lcDataFork)
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if forkyStore.optimistic_header != oldOptimistic.forky(lcDataFork):
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didProgress = true
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when obj isnot SomeForkedLightClientUpdateWithFinality:
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didSignificantProgress = true
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if self.onOptimisticHeader != nil:
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self.onOptimisticHeader()
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if oldFinalized.kind <= lcDataFork:
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oldFinalized.migrateToDataFork(lcDataFork)
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if forkyStore.finalized_header != oldFinalized.forky(lcDataFork):
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didProgress = true
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didSignificantProgress = true
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if self.onFinalizedHeader != nil:
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self.onFinalizedHeader()
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if forkyStore.is_next_sync_committee_known != oldNextCommitteeKnown:
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didProgress = true
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if didProgress:
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when obj is Nothing:
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discard
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elif obj is ForkedLightClientBootstrap:
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if self.bootstrapObserver != nil:
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self.bootstrapObserver(obj)
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elif obj is ForkedLightClientUpdate:
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if self.updateObserver != nil:
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self.updateObserver(obj)
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elif obj is ForkedLightClientFinalityUpdate:
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if self.finalityUpdateObserver != nil:
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self.finalityUpdateObserver(obj)
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elif obj is ForkedLightClientOptimisticUpdate:
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if self.optimisticUpdateObserver != nil:
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self.optimisticUpdateObserver(obj)
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else: raiseAssert "Unreachable"
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didSignificantProgress
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template withReportedProgress(body: untyped): bool =
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withReportedProgress(Nothing(), body)
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proc storeObject*(
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self: var LightClientProcessor,
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src: MsgSource, wallTime: BeaconTime,
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obj: SomeForkedLightClientObject): Result[bool, VerifierError] =
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## storeObject is the main entry point for unvalidated light client objects -
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## all untrusted objects pass through here. When storing an object, we will
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## update the `LightClientStore` accordingly
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let
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startTick = Moment.now()
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didSignificantProgress =
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withReportedProgress(obj):
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? self.processObject(obj, wallTime)
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let
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storeObjectTick = Moment.now()
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storeObjectDur = storeObjectTick - startTick
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light_client_store_object_duration_seconds.observe(
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storeObjectDur.toFloatSeconds())
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let objSlot = withForkyObject(obj):
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when lcDataFork > LightClientDataFork.None:
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when forkyObject is ForkyLightClientBootstrap:
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forkyObject.header.beacon.slot
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elif forkyObject is SomeForkyLightClientUpdateWithFinality:
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forkyObject.finalized_header.beacon.slot
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else:
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forkyObject.attested_header.beacon.slot
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else:
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GENESIS_SLOT
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withForkyStore(self.store[]):
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when lcDataFork > LightClientDataFork.None:
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debug "LC object processed",
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finalizedSlot = forkyStore.finalized_header.beacon.slot,
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optimisticSlot = forkyStore.optimistic_header.beacon.slot,
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kind = typeof(obj).name,
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objectSlot = objSlot,
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storeObjectDur
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ok didSignificantProgress
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proc resetToFinalizedHeader*(
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self: var LightClientProcessor,
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header: ForkedLightClientHeader,
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current_sync_committee: SyncCommittee) =
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discard withReportedProgress:
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withForkyHeader(header):
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when lcDataFork > LightClientDataFork.None:
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self.store[] = ForkedLightClientStore(kind: lcDataFork)
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template forkyStore: untyped = self.store[].forky(lcDataFork)
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forkyStore = lcDataFork.LightClientStore(
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finalized_header: forkyHeader,
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current_sync_committee: current_sync_committee,
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optimistic_header: forkyHeader)
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debug "LC reset to finalized header",
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finalizedSlot = forkyStore.finalized_header.beacon.slot,
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optimisticSlot = forkyStore.optimistic_header.beacon.slot
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else:
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self.store[].reset()
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debug "LC reset"
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# Enqueue
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# ------------------------------------------------------------------------------
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proc addObject*(
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self: var LightClientProcessor,
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src: MsgSource,
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obj: SomeForkedLightClientObject,
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resfut: Future[Result[void, VerifierError]] = nil) =
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## Enqueue a Gossip-validated light client object for verification
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# Backpressure:
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# Only one object is validated at any time -
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# Light client objects are always "fast" to process
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# Producers:
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# - Gossip:
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# - `LightClientFinalityUpdate`
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# - `LightClientOptimisticUpdate`
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# - `LightClientManager`:
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# - `GetLightClientBootstrap`
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# - `LightClientUpdatesByRange`
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# - `GetLightClientFinalityUpdate`
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# - `GetLightClientOptimisticUpdate`
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let
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wallTime = self.getBeaconTime()
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(afterGenesis, wallSlot) = wallTime.toSlot()
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if not afterGenesis:
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error "Processing LC object before genesis, clock turned back?"
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quit 1
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let res = self.storeObject(src, wallTime, obj)
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if resfut != nil:
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if res.isOk:
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resfut.complete(Result[void, VerifierError].ok())
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else:
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resfut.complete(Result[void, VerifierError].err(res.error))
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# Message validators
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# ------------------------------------------------------------------------------
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func toValidationError(
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self: var LightClientProcessor,
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r: Result[bool, VerifierError],
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wallTime: BeaconTime,
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obj: SomeForkedLightClientObject): Result[void, ValidationError] =
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if r.isOk:
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let didSignificantProgress = r.get
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if didSignificantProgress:
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let
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signature_slot = withForkyObject(obj):
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when lcDataFork > LightClientDataFork.None:
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forkyObject.signature_slot
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else:
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GENESIS_SLOT
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currentTime = wallTime + MAXIMUM_GOSSIP_CLOCK_DISPARITY
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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.
|
|
# [IGNORE] The `optimistic_update` is received after the block
|
|
# at `signature_slot` was given enough time to propagate through
|
|
# the network.
|
|
return errIgnore(typeof(obj).name & ": received too early")
|
|
ok()
|
|
else:
|
|
when obj is ForkedLightClientOptimisticUpdate:
|
|
# [IGNORE] The `optimistic_update` either matches corresponding fields
|
|
# of the most recently forwarded `LightClientFinalityUpdate` (if any),
|
|
# or it advances the `optimistic_header` of the local `LightClientStore`
|
|
if obj.matches(self.latestFinalityUpdate):
|
|
return ok()
|
|
# [IGNORE] The `finality_update` advances the `finalized_header` of the
|
|
# local `LightClientStore`.
|
|
errIgnore(typeof(obj).name & ": no significant progress")
|
|
else:
|
|
case r.error
|
|
of VerifierError.Invalid:
|
|
# [REJECT] The `finality_update` is valid.
|
|
# [REJECT] The `optimistic_update` is valid.
|
|
errReject($r.error)
|
|
of VerifierError.MissingParent,
|
|
VerifierError.UnviableFork,
|
|
VerifierError.Duplicate:
|
|
# [IGNORE] The `finalized_header.beacon.slot` is greater than that of
|
|
# all previously forwarded `finality_update`s
|
|
# [IGNORE] The `attested_header.beacon.slot` is greater than that of all
|
|
# previously forwarded `optimistic_update`s
|
|
errIgnore($r.error)
|
|
|
|
# https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.1/specs/altair/light-client/sync-protocol.md#process_light_client_finality_update
|
|
proc processLightClientFinalityUpdate*(
|
|
self: var LightClientProcessor, src: MsgSource,
|
|
finality_update: ForkedLightClientFinalityUpdate
|
|
): Result[void, ValidationError] =
|
|
let
|
|
wallTime = self.getBeaconTime()
|
|
r = self.storeObject(src, wallTime, finality_update)
|
|
v = self.toValidationError(r, wallTime, finality_update)
|
|
if v.isErr:
|
|
return checkedResult(v.error, self.strictVerification)
|
|
|
|
self.latestFinalityUpdate = finality_update.toOptimistic
|
|
v
|
|
|
|
# https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.1/specs/altair/light-client/sync-protocol.md#process_light_client_finality_update
|
|
proc processLightClientOptimisticUpdate*(
|
|
self: var LightClientProcessor, src: MsgSource,
|
|
optimistic_update: ForkedLightClientOptimisticUpdate
|
|
): Result[void, ValidationError] =
|
|
let
|
|
wallTime = self.getBeaconTime()
|
|
r = self.storeObject(src, wallTime, optimistic_update)
|
|
v = self.toValidationError(r, wallTime, optimistic_update)
|
|
if v.isErr:
|
|
return checkedResult(v.error, self.strictVerification)
|
|
|
|
let
|
|
latestFinalitySlot = withForkyOptimisticUpdate(self.latestFinalityUpdate):
|
|
when lcDataFork > LightClientDataFork.None:
|
|
forkyOptimisticUpdate.attested_header.beacon.slot
|
|
else:
|
|
GENESIS_SLOT
|
|
attestedSlot = withForkyOptimisticUpdate(optimistic_update):
|
|
when lcDataFork > LightClientDataFork.None:
|
|
forkyOptimisticUpdate.attested_header.beacon.slot
|
|
else:
|
|
GENESIS_SLOT
|
|
if attestedSlot >= latestFinalitySlot:
|
|
self.latestFinalityUpdate.reset() # Only forward once
|
|
v
|