nimbus-eth2/beacon_chain/beacon_node_light_client.nim

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# beacon_chain
# Copyright (c) 2022 Status Research & Development GmbH
# Licensed and distributed under either of
# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.
{.push raises: [Defect].}
# This implements the pre-release proposal of the libp2p based light client sync
# protocol. See https://github.com/ethereum/consensus-specs/pull/2802
import
chronicles,
./beacon_node
logScope: topics = "beacnde"
proc initLightClient*(
node: BeaconNode,
2022-06-21 08:29:16 +00:00
rng: ref HmacDrbgContext,
cfg: RuntimeConfig,
forkDigests: ref ForkDigests,
getBeaconTime: GetBeaconTimeFn,
genesis_validators_root: Eth2Digest) =
template config(): auto = node.config
# Creating a light client is not dependent on `lightClientEnable`
# because the light client module also handles gossip subscriptions
# for broadcasting light client data as a server.
let
optimisticProcessor = proc(signedBlock: ForkedMsgTrustedSignedBeaconBlock):
Future[void] {.async.} =
debug "New LC optimistic block",
opt = signedBlock.toBlockId(),
dag = node.dag.head.bid,
wallSlot = node.currentSlot
return
optSync = initLCOptimisticSync(
node.network, getBeaconTime, optimisticProcessor,
config.safeSlotsToImportOptimistically)
lightClient = createLightClient(
node.network, rng, config, cfg, forkDigests, getBeaconTime,
genesis_validators_root, LightClientFinalizationMode.Strict)
if config.lightClientEnable.get:
proc shouldSyncOptimistically(slot: Slot): bool =
const
# Minimum number of slots to be ahead of DAG to use optimistic sync
minProgress = 8 * SLOTS_PER_EPOCH
# Maximum age of light client optimistic header to use optimistic sync
maxAge = 2 * SLOTS_PER_EPOCH
if slot < getStateField(node.dag.headState, slot) + minProgress:
false
elif getBeaconTime().slotOrZero > slot + maxAge:
false
else:
true
proc onFinalizedHeader(lightClient: LightClient) =
let optimisticHeader = lightClient.optimisticHeader.valueOr:
return
if not shouldSyncOptimistically(optimisticHeader.slot):
return
let finalizedHeader = lightClient.finalizedHeader.valueOr:
return
optSync.setOptimisticHeader(optimisticHeader)
optSync.setFinalizedHeader(finalizedHeader)
proc onOptimisticHeader(lightClient: LightClient) =
let optimisticHeader = lightClient.optimisticHeader.valueOr:
return
if not shouldSyncOptimistically(optimisticHeader.slot):
return
optSync.setOptimisticHeader(optimisticHeader)
lightClient.onFinalizedHeader = onFinalizedHeader
lightClient.onOptimisticHeader = onOptimisticHeader
lightClient.trustedBlockRoot = config.lightClientTrustedBlockRoot
elif config.lightClientTrustedBlockRoot.isSome:
warn "Ignoring `lightClientTrustedBlockRoot`, light client not enabled",
lightClientEnable = config.lightClientEnable.get,
lightClientTrustedBlockRoot = config.lightClientTrustedBlockRoot
node.lcOptSync = optSync
node.lightClient = lightClient
proc startLightClient*(node: BeaconNode) =
if not node.config.lightClientEnable.get:
return
node.lcOptSync.start()
node.lightClient.start()
proc installLightClientMessageValidators*(node: BeaconNode) =
let eth2Processor =
if node.config.lightClientDataServe.get:
# Process gossip using both full node and light client
node.processor
elif node.config.lightClientEnable.get:
# Only process gossip using light client
nil
else:
# Light client topics will never be subscribed to, no validators needed
return
node.lightClient.installMessageValidators(eth2Processor)
proc updateLightClientGossipStatus*(
node: BeaconNode, slot: Slot, dagIsBehind: bool) =
let isBehind =
if node.config.lightClientDataServe.get:
# Forward DAG's readiness to handle light client gossip
dagIsBehind
else:
# Full node is not interested in gossip
true
node.lightClient.updateGossipStatus(slot, some isBehind)
proc updateLightClientFromDag*(node: BeaconNode) =
if not node.config.lightClientEnable.get:
return
if node.config.lightClientTrustedBlockRoot.isSome:
return
let
dagHead = node.dag.finalizedHead
dagPeriod = dagHead.slot.sync_committee_period
if dagHead.slot < node.dag.cfg.ALTAIR_FORK_EPOCH.start_slot:
return
let lcHeader = node.lightClient.finalizedHeader
if lcHeader.isSome:
if dagPeriod <= lcHeader.get.slot.sync_committee_period:
return
let
bdata = node.dag.getForkedBlock(dagHead.blck.bid).valueOr:
return
header = bdata.toBeaconBlockHeader
current_sync_committee = block:
var tmpState = assignClone(node.dag.headState)
node.dag.currentSyncCommitteeForPeriod(tmpState[], dagPeriod).valueOr:
return
node.lightClient.resetToFinalizedHeader(header, current_sync_committee)