import deques, tables, hashes, options, chronos, web3, json, chronicles, spec/[datatypes, digest, crypto, beaconstate, helpers] contract(DepositContract): proc deposit(pubkey: Bytes48, withdrawalCredentials: Bytes32, signature: Bytes96, deposit_data_root: FixedBytes[32]) proc get_deposit_root(): FixedBytes[32] proc get_deposit_count(): Bytes8 proc DepositEvent(pubkey: Bytes48, withdrawalCredentials: Bytes32, amount: Bytes8, signature: Bytes96, index: Bytes8) {.event.} # TODO # The raises list of this module are still not usable due to general # Exceptions being reported from Chronos's asyncfutures2. type Eth1BlockNumber* = uint64 Eth1BlockTimestamp* = uint64 Eth1Block* = ref object number*: Eth1BlockNumber timestamp*: Eth1BlockTimestamp deposits*: seq[Deposit] voteData*: Eth1Data Eth1Chain* = object blocks: Deque[Eth1Block] blocksByHash: Table[BlockHash, Eth1Block] MainchainMonitor* = ref object startBlock: BlockHash depositContractAddress: Address dataProviderFactory*: DataProviderFactory genesisState: NilableBeaconStateRef genesisStateFut: Future[void] eth1Chain: Eth1Chain depositQueue: AsyncQueue[DepositQueueElem] runFut: Future[void] Web3EventType = enum NewEvent RemovedEvent DepositQueueElem = (BlockHash, Web3EventType) DataProvider* = object of RootObj DataProviderRef* = ref DataProvider DataProviderFactory* = object desc: string new: proc(depositContractAddress: Address): Future[DataProviderRef] {. gcsafe # raises: [Defect] .} Web3DataProvider* = object of DataProvider url: string web3: Web3 ns: Sender[DepositContract] subscription: Subscription Web3DataProviderRef* = ref Web3DataProvider ReorgDepthLimitExceeded = object of CatchableError CorruptDataProvider = object of CatchableError DisconnectHandler* = proc () {.gcsafe, raises: [Defect].} DepositEventHandler* = proc ( pubkey: Bytes48, withdrawalCredentials: Bytes32, amount: Bytes8, signature: Bytes96, merkleTreeIndex: Bytes8, j: JsonNode) {.raises: [Defect], gcsafe.} const reorgDepthLimit = 1000 # TODO Nim's analysis on the lock level of the methods in this # module seems broken. Investigate and file this as an issue. {.push warning[LockLevel]: off.} # https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/validator.md#get_eth1_data func compute_time_at_slot(state: BeaconState, slot: Slot): uint64 = return state.genesis_time + slot * SECONDS_PER_SLOT # https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/validator.md#get_eth1_data func voting_period_start_time*(state: BeaconState): uint64 = let eth1_voting_period_start_slot = state.slot - state.slot mod SLOTS_PER_ETH1_VOTING_PERIOD.uint64 return compute_time_at_slot(state, eth1_voting_period_start_slot) # https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/validator.md#get_eth1_data func is_candidate_block(blk: Eth1Block, period_start: uint64): bool = (blk.timestamp + SECONDS_PER_ETH1_BLOCK.uint64 * ETH1_FOLLOW_DISTANCE.uint64 <= period_start) and (blk.timestamp + SECONDS_PER_ETH1_BLOCK.uint64 * ETH1_FOLLOW_DISTANCE.uint64 * 2 >= period_start) func asEth2Digest(x: BlockHash): Eth2Digest = Eth2Digest(data: array[32, byte](x)) template asBlockHash(x: Eth2Digest): BlockHash = BlockHash(x.data) func getDepositsInRange(eth1Chain: Eth1Chain, sinceBlock, latestBlock: Eth1BlockNumber): seq[Deposit] = ## Returns all deposits that happened AFTER the block `sinceBlock` (not inclusive). ## The deposits in `latestBlock` will be included. if latestBlock <= sinceBlock: return let firstBlockInCache = eth1Chain.blocks[0].number # This function should be used with indices obtained with `eth1Chain.findBlock`. # This guarantess that both of these indices will be valid: doAssert sinceBlock >= firstBlockInCache and int(latestBlock - firstBlockInCache) < eth1Chain.blocks.len let sinceBlockIdx = sinceBlock - firstBlockInCache latestBlockIdx = latestBlock - firstBlockInCache for i in (sinceBlockIdx + 1) ..< latestBlockIdx: result.add eth1Chain.blocks[i].deposits template findBlock*(eth1Chain: Eth1Chain, hash: BlockHash): Eth1Block = eth1Chain.blocksByHash.getOrDefault(hash, nil) template findBlock*(eth1Chain: Eth1Chain, eth1Data: Eth1Data): Eth1Block = getOrDefault(eth1Chain.blocksByHash, asBlockHash(eth1Data.block_hash), nil) proc findParent*(eth1Chain: Eth1Chain, blk: BlockObject): Eth1Block = result = eth1Chain.findBlock(blk.parentHash) # a distinct type is stipped here: let blockNumber = Eth1BlockNumber(blk.number) if result != nil and result.number != blockNumber - 1: debug "Found inconsistent numbering of Eth1 blocks. Ignoring block.", blockHash = blk.hash.toHex, blockNumber, parentHash = blk.parentHash.toHex, parentNumber = result.number result = nil when false: func getCacheIdx(eth1Chain: Eth1Chain, blockNumber: Eth1BlockNumber): int = if eth1Chain.blocks.len == 0: return -1 let idx = blockNumber - eth1Chain.blocks[0].number if idx < 0 or idx >= eth1Chain.blocks.len: return -1 idx func `{}`*(eth1Chain: Eth1Chain, blockNumber: Eth1BlockNumber): Eth1Block = ## Finds a block in our cache that corresponds to a particular Eth block ## number. May return `nil` if we don't have such a block in the cache. let idx = eth1Chain.getCacheIdx(blockNumber) if idx != -1: eth1Chain.blocks[idx] else: nil func latestCandidateBlock(eth1Chain: Eth1Chain, periodStart: uint64): Eth1Block = for i in countdown(eth1Chain.blocks.len - 1, 0): let blk = eth1Chain.blocks[i] if is_candidate_block(blk, periodStart): return blk func trimHeight(eth1Chain: var Eth1Chain, blockNumber: Eth1BlockNumber) = ## Removes all blocks above certain `blockNumber` if eth1Chain.blocks.len == 0: return let newLen = max(0, int(blockNumber - eth1Chain.blocks[0].number + 1)) for i in newLen ..< eth1Chain.blocks.len: let removed = eth1Chain.blocks.popLast eth1Chain.blocksByHash.del removed.voteData.block_hash.asBlockHash template purgeChain*(eth1Chain: var Eth1Chain, blk: Eth1Block) = ## This is used when we discover that a previously considered block ## is no longer part of the selected chain (due to a reorg). We can ## then remove from our chain together with all blocks that follow it. trimHeight(eth1Chain, blk.number - 1) func purgeChain*(eth1Chain: var Eth1Chain, blockHash: BlockHash) = let blk = eth1Chain.findBlock(blockHash) if blk != nil: eth1Chain.purgeChain(blk) template purgeDescendants*(eth1CHain: Eth1Chain, blk: Eth1Block) = trimHeight(eth1Chain, blk.number) func addBlock*(eth1Chain: var Eth1Chain, newBlock: Eth1Block) = if eth1Chain.blocks.len > 0: doAssert eth1Chain.blocks.peekLast.number + 1 == newBlock.number eth1Chain.blocks.addLast newBlock eth1Chain.blocksByHash[newBlock.voteData.block_hash.asBlockHash] = newBlock func totalDeposits*(eth1Chain: Eth1Chain): int = for blk in eth1Chain.blocks: result += blk.deposits.len func allDeposits*(eth1Chain: Eth1Chain): seq[Deposit] = for blk in eth1Chain.blocks: result.add blk.deposits template hash*(x: Eth1Block): Hash = hash(x.voteData.block_hash.data) template notImplemented = doAssert false, "Method not implemented" method getBlockByHash*(p: DataProviderRef, hash: BlockHash): Future[BlockObject] {. base gcsafe locks: 0 # raises: [Defect] .} = discard # notImplemented method onDisconnect*(p: DataProviderRef, handler: DisconnectHandler) {. base gcsafe locks: 0 # raises: [] .} = notImplemented method onDepositEvent*(p: DataProviderRef, startBlock: Eth1BlockNumber, handler: DepositEventHandler): Future[void] {. base gcsafe locks: 0 # raises: [] .} = notImplemented method close*(p: DataProviderRef): Future[void] {. base gcsafe locks: 0 # raises: [Defect] .} = notImplemented method fetchDepositData*(p: DataProviderRef, web3Block: BlockObject): Future[Eth1Block] {. base gcsafe locks: 0 # raises: [Defect, CatchableError] .} = notImplemented # https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/validator.md#get_eth1_data func getBlockProposalData*(eth1Chain: Eth1Chain, state: BeaconState): (Eth1Data, seq[Deposit]) = template voteForNoChange() = return (state.eth1_data, newSeq[Deposit]()) let prevBlock = eth1Chain.findBlock(state.eth1_data) if prevBlock == nil: # The Eth1 block currently referenced in the BeaconState is unknown to us. # This situation is not specifically covered in the honest validator spec, # but there is a similar condition where none of the eth1_data_votes is # present in our worldview. The suggestion there is to vote for "no change" # and we'll do the same here: voteForNoChange() let periodStart = voting_period_start_time(state) var otherVotesCountTable = initCountTable[Eth1Block]() for vote in state.eth1_data_votes: let eth1Block = eth1Chain.findBlock(vote) if eth1Block != nil and is_candidate_block(eth1Block, periodStart): otherVotesCountTable.inc eth1Block var ourVote: Eth1Block if otherVotesCountTable.len > 0: ourVote = otherVotesCountTable.largest.key else: ourVote = eth1Chain.latestCandidateBlock(periodStart) if ourVote == nil: voteForNoChange() (ourVote.voteData, eth1Chain.getDepositsInRange(prevBlock.number, ourVote.number)) template getBlockProposalData*(m: MainchainMonitor, state: BeaconState): untyped = getBlockProposalData(m.eth1Chain, state) proc init*(T: type MainchainMonitor, dataProviderFactory: DataProviderFactory, depositContractAddress: string, startBlock: Eth2Digest): T = T(depositContractAddress: Address.fromHex(depositContractAddress), depositQueue: newAsyncQueue[DepositQueueElem](), startBlock: BlockHash(startBlock.data), dataProviderFactory: dataProviderFactory) const MIN_GENESIS_TIME = 0 proc readJsonDeposits(json: JsonNode): seq[Deposit] = if json.kind != JArray: raise newException(CatchableError, "Web3 provider didn't return a list of deposit events") for logEvent in json: var logData = strip0xPrefix(json["data"].getStr) var pubkey: Bytes48 withdrawalCredentials: Bytes32 amount: Bytes8 signature: Bytes96 index: Bytes8 var offset = 0 offset = decode(logData, offset, pubkey) offset = decode(logData, offset, withdrawalCredentials) offset = decode(logData, offset, amount) offset = decode(logData, offset, signature) offset = decode(logData, offset, index) result.add Deposit( # proof: TODO data: DepositData( pubkey: ValidatorPubKey.init(array[48, byte](pubkey)), withdrawal_credentials: Eth2Digest(data: array[32, byte](withdrawalCredentials)), amount: bytes_to_int(array[8, byte](amount)), signature: ValidatorSig.init(array[96, byte](signature)))) proc checkForGenesisEvent(m: MainchainMonitor) = if not m.genesisState.isNil: return let lastBlock = m.eth1Chain.blocks.peekLast const totalDepositsNeeded = max(SLOTS_PER_EPOCH, MIN_GENESIS_ACTIVE_VALIDATOR_COUNT) if lastBlock.timestamp.uint64 >= MIN_GENESIS_TIME.uint64 and m.eth1Chain.totalDeposits >= totalDepositsNeeded: # This block is a genesis candidate let startTime = lastBlock.timestamp.uint64 var s = initialize_beacon_state_from_eth1(lastBlock.voteData.block_hash, startTime, m.eth1Chain.allDeposits, {}) if is_valid_genesis_state(s[]): # https://github.com/ethereum/eth2.0-pm/tree/6e41fcf383ebeb5125938850d8e9b4e9888389b4/interop/mocked_start#create-genesis-state s.genesis_time = startTime m.genesisState = s if not m.genesisStateFut.isNil: m.genesisStateFut.complete() m.genesisStateFut = nil proc processDeposits(m: MainchainMonitor, dataProvider: DataProviderRef) {. async # raises: [Defect] .} = # ATTENTION! # Please note that this code is using a queue to guarantee the # strict serial order of processing of deposits. If we had the # same code embedded in the deposit contracts events handler, # it could easily re-order the steps due to the intruptable # interleaved execution of async code. while true: let (blockHash, eventType) = await m.depositQueue.popFirst() if eventType == RemovedEvent: m.eth1Chain.purgeChain(blockHash) continue let cachedBlock = m.eth1Chain.findBlock(blockHash) if cachedBlock == nil: try: let web3Block = await dataProvider.getBlockByHash(blockHash) eth1Block = await dataProvider.fetchDepositData(web3Block) if m.eth1Chain.blocks.len > 0: var cachedParent = m.eth1Chain.findParent(web3Block) if cachedParent == nil: # We are missing the parent block. # This shouldn't be happening if the deposits events are reported in # proper order, but nevertheless let's try to repair our chain: var chainOfParents = newSeq[Eth1Block]() var parentHash = web3Block.parentHash var expectedParentBlockNumber = web3Block.number.uint64 - 1 warn "Eth1 parent block missing. Attempting to request from the network", parentHash = parentHash.toHex while true: if chainOfParents.len > reorgDepthLimit: error "Detected Eth1 re-org exceeded the maximum depth limit", headBlockHash = web3Block.hash.toHex, ourHeadHash = m.eth1Chain.blocks.peekLast.voteData.block_hash raise newException(ReorgDepthLimitExceeded, "Reorg depth limit exceeded") let parentWeb3Block = await dataProvider.getBlockByHash(parentHash) if parentWeb3Block.number.uint64 != expectedParentBlockNumber: error "Eth1 data provider supplied invalid parent block", parentBlockNumber = parentWeb3Block.number.uint64, expectedParentBlockNumber, parentHash = parentHash.toHex raise newException(CorruptDataProvider, "Parent block with incorrect number") chainOfParents.add(await dataProvider.fetchDepositData(parentWeb3Block)) let localParent = m.eth1Chain.findParent(parentWeb3Block) if localParent != nil: m.eth1Chain.purgeDescendants(localParent) for i in countdown(chainOfParents.len - 1, 0): m.eth1Chain.addBlock chainOfParents[i] cachedParent = m.eth1Chain.blocks.peekLast break dec expectedParentBlockNumber parentHash = parentWeb3Block.parentHash m.eth1Chain.purgeDescendants(cachedParent) m.eth1Chain.addBlock eth1Block m.checkForGenesisEvent() except CatchableError: # Connection problem? Put the unprocessed deposit back to queue. # Raising the exception here will lead to a restart of the whole monitor. m.depositQueue.addFirstNoWait((blockHash, eventType)) raise proc isRunning*(m: MainchainMonitor): bool = not m.runFut.isNil proc getGenesis*(m: MainchainMonitor): Future[BeaconStateRef] {.async.} = if m.genesisState.isNil: if m.genesisStateFut.isNil: m.genesisStateFut = newFuture[void]("getGenesis") await m.genesisStateFut m.genesisStateFut = nil if m.genesisState != nil: return m.genesisState else: result = new BeaconStateRef # make the compiler happy raiseAssert "Unreachable code" method getBlockByHash*(p: Web3DataProviderRef, hash: BlockHash): Future[BlockObject] = discard # p.web3.provider.eth_getBlockByHash(hash, false) method close*(p: Web3DataProviderRef): Future[void] {.async, locks: 0.} = if p.subscription != nil: await p.subscription.unsubscribe() await p.web3.close() method fetchDepositData*(p: Web3DataProviderRef, web3Block: BlockObject): Future[Eth1Block] {.async, locks: 0.} = let blockHash = web3Block.hash depositRoot = await p.ns.get_deposit_root.call(blockNumber = web3Block.number.uint64) rawCount = await p.ns.get_deposit_count.call(blockNumber = web3Block.number.uint64) depositCount = bytes_to_int(array[8, byte](rawCount)) depositsJson = await p.ns.getJsonLogs(DepositEvent, blockHash = some(blockHash)) deposits = readJsonDeposits(depositsJson) return Eth1Block( number: Eth1BlockNumber(web3Block.number), timestamp: Eth1BlockTimestamp(web3Block.timestamp), deposits: deposits, voteData: Eth1Data(deposit_root: depositRoot.asEth2Digest, deposit_count: depositCount, block_hash: blockHash.asEth2Digest)) method onDisconnect*(p: Web3DataProviderRef, handler: DisconnectHandler) {. gcsafe locks: 0 # raises: [] .} = p.web3.onDisconnect = handler method onDepositEvent*(p: Web3DataProviderRef, startBlock: Eth1BlockNumber, handler: DepositEventHandler): Future[void] {. async gcsafe locks: 0 # raises: [] .} = if p.subscription != nil: await p.subscription.unsubscribe() p.subscription = await p.ns.subscribe( DepositEvent, %*{"fromBlock": startBlock}, handler) proc getBlockNumber(p: DataProviderRef, hash: BlockHash): Future[Quantity] {.async.} = debug "Querying block number", hash = $hash try: let blk = await p.getBlockByHash(hash) return blk.number except CatchableError as exc: notice "Failed to get Eth1 block number from hash", hash = $hash, err = exc.msg raise proc new*(T: type Web3DataProvider, web3Url: string, depositContractAddress: Address): Future[ref Web3DataProvider] {. async # raises: [Defect] .} = try: type R = ref T let web3 = await newWeb3(web3Url) ns = web3.contractSender(DepositContract, depositContractAddress) return R(url: web3Url, web3: web3, ns: ns) except CatchableError: return nil func web3Provider*(web3Url: string): DataProviderFactory = proc factory(depositContractAddress: Address): Future[DataProviderRef] {.async.} = result = await Web3DataProvider.new(web3Url, depositContractAddress) DataProviderFactory(desc: "web3(" & web3Url & ")", new: factory) proc run(m: MainchainMonitor, delayBeforeStart: Duration) {.async.} = if delayBeforeStart != ZeroDuration: await sleepAsync(delayBeforeStart) let dataProvider = await m.dataProviderFactory.new(m.depositContractAddress) if dataProvider == nil: error "Failed to initialize Eth1 data provider", provider = m.dataProviderFactory.desc raise newException(CatchableError, "Failed to initialize Eth1 data provider") defer: await close(dataProvider) let processFut = m.processDeposits(dataProvider) defer: await processFut dataProvider.onDisconnect do: error "Eth1 data provider disconnected", provider = m.dataProviderFactory.desc processFut.cancel() let startBlkNum = await dataProvider.getBlockNumber(m.startBlock) notice "Monitoring eth1 deposits", fromBlock = startBlkNum.uint64, contract = $m.depositContractAddress, url = m.dataProviderFactory.desc await dataProvider.onDepositEvent(Eth1BlockNumber(startBlkNum)) do ( pubkey: Bytes48, withdrawalCredentials: Bytes32, amount: Bytes8, signature: Bytes96, merkleTreeIndex: Bytes8, j: JsonNode) {.raises: [Defect], gcsafe.}: try: let blockHash = BlockHash.fromHex(j["blockHash"].getStr()) eventType = if j.hasKey("removed"): RemovedEvent else: NewEvent m.depositQueue.addLastNoWait((blockHash, eventType)) except CatchableError as exc: warn "Received invalid deposit", err = exc.msg, j except Exception as err: # chronos still raises exceptions which inherit directly from Exception if err[] of Defect: raise (ref Defect)(err) else: warn "Received invalid deposit", err = err.msg, j proc start(m: MainchainMonitor, delayBeforeStart: Duration) = if m.runFut.isNil: let runFut = m.run(delayBeforeStart) m.runFut = runFut runFut.addCallback do (p: pointer): if runFut.failed: if runFut.error[] of CatchableError: if runFut == m.runFut: error "Mainchain monitor failure, restarting", err = runFut.error.msg m.runFut = nil m.start(5.seconds) else: fatal "Fatal exception reached", err = runFut.error.msg quit 1 proc start*(m: MainchainMonitor) {.inline.} = m.start(0.seconds) proc stop*(m: MainchainMonitor) = if not m.runFut.isNil: m.runFut.cancel() m.runFut = nil proc getLatestEth1BlockHash*(url: string): Future[Eth2Digest] {.async.} = let web3 = await newWeb3(url) try: let blk = await web3.provider.eth_getBlockByNumber("latest", false) return Eth2Digest(data: array[32, byte](blk.hash)) finally: await web3.close() {.pop.}