# nim-eth # Copyright (c) 2018-2022 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. import std/[sets, options, random, hashes, sequtils, math, tables, times], chronicles, chronos, eth/p2p, eth/p2p/[private/p2p_types, peer_pool], stew/byteutils, "."/[protocol, types], ../core/[chain, clique/clique_sealer, eip4844, gaslimit, withdrawals], ../core/pow/difficulty, ../constants, ../utils/utils, ../common/common {.push raises:[].} logScope: topics = "legacy-sync" const minPeersToStartSync* = 2 # Wait for consensus of at least this # number of peers before syncing CleanupInterval = initDuration(minutes = 20) type #SyncStatus = enum # syncSuccess # syncNotEnoughPeers # syncTimeOut HashToTime = TableRef[Hash256, Time] BlockchainSyncDefect* = object of Defect ## Catch and relay exception WantedBlocksState = enum Initial, Requested, Received, Persisted WantedBlocks = object isHash: bool hash: Hash256 startIndex: BlockNumber numBlocks: uint state: WantedBlocksState headers: seq[BlockHeader] bodies: seq[BlockBody] LegacySyncRef* = ref object workQueue: seq[WantedBlocks] chain: ChainRef peerPool: PeerPool trustedPeers: HashSet[Peer] hasOutOfOrderBlocks: bool busyPeers: HashSet[Peer] knownByPeer: Table[Peer, HashToTime] lastCleanup: Time # ------------------------------------------------------------------------------ # Private functions: sync progress # ------------------------------------------------------------------------------ template endBlockNumber(ctx: LegacySyncRef): BlockNumber = ctx.chain.com.syncHighest template `endBlockNumber=`(ctx: LegacySyncRef, number: BlockNumber) = ctx.chain.com.syncHighest = number # Block which was downloaded and verified template finalizedBlock(ctx: LegacySyncRef): BlockNumber = ctx.chain.com.syncCurrent template `finalizedBlock=`(ctx: LegacySyncRef, number: BlockNumber) = ctx.chain.com.syncCurrent = number # ------------------------------------------------------------------------------ # Private functions: peers related functions # ------------------------------------------------------------------------------ proc hash*(p: Peer): Hash = hash(cast[pointer](p)) proc cleanupKnownByPeer(ctx: LegacySyncRef) = let now = getTime() var tmp = initHashSet[Hash256]() for _, map in ctx.knownByPeer: for hash, time in map: if time - now >= CleanupInterval: tmp.incl hash for hash in tmp: map.del(hash) tmp.clear() var tmpPeer = initHashSet[Peer]() for peer, map in ctx.knownByPeer: if map.len == 0: tmpPeer.incl peer for peer in tmpPeer: ctx.knownByPeer.del peer ctx.lastCleanup = now proc addToKnownByPeer(ctx: LegacySyncRef, blockHash: Hash256, peer: Peer): bool = var map: HashToTime ctx.knownByPeer.withValue(peer, val) do: map = val[] result = true do: map = newTable[Hash256, Time]() ctx.knownByPeer[peer] = map result = false map[blockHash] = getTime() proc getPeers(ctx: LegacySyncRef, thisPeer: Peer): seq[Peer] = # do not send back block/blockhash to thisPeer for peer in peers(ctx.peerPool): if peer != thisPeer: result.add peer proc handleLostPeer(ctx: LegacySyncRef) = # TODO: ask the PeerPool for new connections and then call # `obtainBlocksFromPeer` discard # ------------------------------------------------------------------------------ # Private functions: validators # ------------------------------------------------------------------------------ proc validateDifficulty(ctx: LegacySyncRef, header, parentHeader: BlockHeader, consensusType: ConsensusType): bool = try: let com = ctx.chain.com case consensusType of ConsensusType.POA: let rc = ctx.chain.clique.calcDifficulty(parentHeader) if rc.isErr: return false if header.difficulty < rc.get(): trace "provided header difficulty is too low", expect=rc.get(), get=header.difficulty return false of ConsensusType.POW: let calcDiffc = com.calcDifficulty(header.timestamp, parentHeader) if header.difficulty < calcDiffc: trace "provided header difficulty is too low", expect=calcDiffc, get=header.difficulty return false of ConsensusType.POS: if header.difficulty != 0.u256: trace "invalid difficulty", expect=0, get=header.difficulty return false return true except CatchableError as e: error "Exception in FastSync.validateDifficulty()", exc = e.name, err = e.msg return false proc validateHeader(ctx: LegacySyncRef, header: BlockHeader, height = none(BlockNumber)): bool {.raises: [CatchableError].} = if header.parentHash == GENESIS_PARENT_HASH: return true let db = ctx.chain.db com = ctx.chain.com var parentHeader: BlockHeader if not db.getBlockHeader(header.parentHash, parentHeader): error "can't get parentHeader", hash=header.parentHash, number=header.blockNumber return false if header.blockNumber != parentHeader.blockNumber + 1.toBlockNumber: trace "invalid block number", expect=parentHeader.blockNumber + 1.toBlockNumber, get=header.blockNumber return false if header.timestamp <= parentHeader.timestamp: trace "invalid timestamp", parent=parentHeader.timestamp, header=header.timestamp return false let consensusType = com.consensus(header) if not ctx.validateDifficulty(header, parentHeader, consensusType): return false if consensusType == ConsensusType.POA: let period = initDuration(seconds = com.cliquePeriod) # Timestamp diff between blocks is lower than PERIOD (clique) if parentHeader.timestamp + period > header.timestamp: trace "invalid timestamp diff (lower than period)", parent=parentHeader.timestamp, header=header.timestamp, period return false var res = com.validateGasLimitOrBaseFee(header, parentHeader) if res.isErr: trace "validate gaslimit error", msg=res.error return false if height.isSome: let dif = height.get() - parentHeader.blockNumber if not (dif < 8.toBlockNumber and dif > 1.toBlockNumber): trace "uncle block has a parent that is too old or too young", dif=dif, height=height.get(), parentNumber=parentHeader.blockNumber return false res = com.validateWithdrawals(header) if res.isErr: trace "validate withdrawals error", msg=res.error return false res = com.validateEip4844Header(header) if res.isErr: trace "validate eip4844 error", msg=res.error return false return true # ------------------------------------------------------------------------------ # Private functions: sync worker # ------------------------------------------------------------------------------ proc broadcastBlockHash(ctx: LegacySyncRef, hashes: seq[NewBlockHashesAnnounce], peers: seq[Peer]) {.async.} = try: var bha = newSeqOfCap[NewBlockHashesAnnounce](hashes.len) for peer in peers: for val in hashes: let alreadyKnownByPeer = ctx.addToKnownByPeer(val.hash, peer) if not alreadyKnownByPeer: bha.add val if bha.len > 0: trace trEthSendNewBlockHashes, numHashes=bha.len, peer await peer.newBlockHashes(bha) bha.setLen(0) except TransportError: debug "Transport got closed during broadcastBlockHash" except CatchableError as e: debug "Exception in broadcastBlockHash", exc = e.name, err = e.msg proc broadcastBlock(ctx: LegacySyncRef, blk: EthBlock, peers: seq[Peer]) {.async.} = try: let db = ctx.chain.db blockHash = blk.header.blockHash td = db.getScore(blk.header.parentHash) + blk.header.difficulty for peer in peers: let alreadyKnownByPeer = ctx.addToKnownByPeer(blockHash, peer) if not alreadyKnownByPeer: trace trEthSendNewBlock, number=blk.header.blockNumber, td=td, hash=short(blockHash), peer await peer.newBlock(blk, td) except TransportError: debug "Transport got closed during broadcastBlock" except CatchableError as e: debug "Exception in broadcastBlock", exc = e.name, err = e.msg proc broadcastBlockHash(ctx: LegacySyncRef, blk: EthBlock, peers: seq[Peer]) {.async.} = try: let bha = NewBlockHashesAnnounce( number: blk.header.blockNumber, hash: blk.header.blockHash ) for peer in peers: let alreadyKnownByPeer = ctx.addToKnownByPeer(bha.hash, peer) if not alreadyKnownByPeer: trace trEthSendNewBlockHashes, number=bha.number, hash=short(bha.hash), peer await peer.newBlockHashes([bha]) except TransportError: debug "Transport got closed during broadcastBlockHash" except CatchableError as e: debug "Exception in broadcastBlockHash", exc = e.name, err = e.msg proc sendBlockOrHash(ctx: LegacySyncRef, peer: Peer) {.async.} = # because peer TD is lower than us, # it become our recipient of block and block hashes # instead of we download from it try: let db = ctx.chain.db peerBlockHash = peer.state(eth).bestBlockHash var peerBlockHeader: BlockHeader if not db.getBlockHeader(peerBlockHash, peerBlockHeader): error "can't get block header", hash=short(peerBlockHash) return let dist = (ctx.finalizedBlock - peerBlockHeader.blockNumber).truncate(int) start = peerBlockHeader.blockNumber + 1.toBlockNumber if dist == 1: # only one block apart, send NewBlock let number = ctx.finalizedBlock var header: BlockHeader var body: BlockBody if not db.getBlockHeader(number, header): error "can't get block header", number=number return let blockHash = header.blockHash if not db.getBlockBody(blockHash, body): error "can't get block body", number=number return let ourTD = db.getScore(blockHash) newBlock = EthBlock( header: header, txs: body.transactions, uncles: body.uncles) trace "send newBlock", number = header.blockNumber, hash = short(header.blockHash), td = ourTD, peer await peer.newBlock(newBlock, ourTD) return if dist > maxHeadersFetch: # distance is too far, ignore this peer return # send hashes in batch var hash: Hash256 number = 0 hashes = newSeqOfCap[NewBlockHashesAnnounce](maxHeadersFetch) while number < dist: let blockNumber = start + number.toBlockNumber if not db.getBlockHash(blockNumber, hash): error "failed to get block hash", number=blockNumber return hashes.add(NewBlockHashesAnnounce( number: blockNumber, hash: hash)) if hashes.len == maxHeadersFetch: trace "send newBlockHashes(batch)", numHashes=hashes.len, peer await peer.newBlockHashes(hashes) hashes.setLen(0) inc number # send the rest of hashes if available if hashes.len > 0: trace "send newBlockHashes(remaining)", numHashes=hashes.len, peer await peer.newBlockHashes(hashes) except TransportError: debug "Transport got closed during obtainBlocksFromPeer" except CatchableError as e: debug "Exception in getBestBlockNumber()", exc = e.name, err = e.msg # no need to exit here, because the context might still have blocks to fetch # from this peer discard e proc endIndex(b: WantedBlocks): BlockNumber = result = b.startIndex result += (b.numBlocks - 1).toBlockNumber proc availableWorkItem(ctx: LegacySyncRef): int = var maxPendingBlock = ctx.finalizedBlock # the last downloaded & processed trace "queue len", length = ctx.workQueue.len result = -1 for i in 0 .. ctx.workQueue.high: case ctx.workQueue[i].state of Initial: # When there is a work item at Initial state, immediatly use this one. # This usually means a previous work item that failed somewhere in the # process, and thus can be reused to work on. return i of Persisted: # In case of Persisted, we can reset this work item to a new one. result = i # No break here to give work items in Initial state priority and to # calculate endBlock. else: discard # Check all endBlocks of all workqueue items to decide on next range of # blocks to collect & process. let endBlock = ctx.workQueue[i].endIndex if endBlock > maxPendingBlock: maxPendingBlock = endBlock let nextRequestedBlock = maxPendingBlock + 1 # If this next block doesn't exist yet according to any of our peers, don't # return a work item (and sync will be stopped). if nextRequestedBlock > ctx.endBlockNumber: return -1 # Increase queue when there are no free (Initial / Persisted) work items in # the queue. At start, queue will be empty. if result == -1: result = ctx.workQueue.len ctx.workQueue.setLen(result + 1) # Create new work item when queue was increased, reset when selected work item # is at Persisted state. var numBlocks = (ctx.endBlockNumber - nextRequestedBlock).truncate(int) + 1 if numBlocks > maxHeadersFetch: numBlocks = maxHeadersFetch ctx.workQueue[result] = WantedBlocks( startIndex: nextRequestedBlock, numBlocks : numBlocks.uint, state : Initial, isHash : false) proc appendWorkItem(ctx: LegacySyncRef, hash: Hash256, startIndex: BlockNumber, numBlocks: uint) = for i in 0 .. ctx.workQueue.high: if ctx.workQueue[i].state == Persisted: ctx.workQueue[i] = WantedBlocks( isHash : true, hash : hash, startIndex: startIndex, numBlocks : numBlocks, state : Initial) return let i = ctx.workQueue.len ctx.workQueue.setLen(i + 1) ctx.workQueue[i] = WantedBlocks( isHash : true, hash : hash, startIndex: startIndex, numBlocks : numBlocks, state : Initial) proc persistWorkItem(ctx: LegacySyncRef, wi: var WantedBlocks): ValidationResult = try: result = ctx.chain.persistBlocks(wi.headers, wi.bodies) except CatchableError as e: error "storing persistent blocks failed", error = $e.name, msg = e.msg result = ValidationResult.Error except Defect as e: # Pass through raise e except Exception as e: # Notorious case where the `Chain` reference applied to `persistBlocks()` # has the compiler traced a possible `Exception` (i.e. `ctx.chain` could # be uninitialised.) error "exception while storing persistent blocks", error = $e.name, msg = e.msg raise (ref Defect)(msg: $e.name & ": " & e.msg) case result of ValidationResult.OK: ctx.finalizedBlock = wi.endIndex wi.state = Persisted of ValidationResult.Error: wi.state = Initial # successful or not, we're done with these blocks wi.headers = @[] wi.bodies = @[] proc persistPendingWorkItems(ctx: LegacySyncRef): (int, ValidationResult) = var nextStartIndex = ctx.finalizedBlock + 1 var keepRunning = true var hasOutOfOrderBlocks = false trace "Looking for out of order blocks" while keepRunning: keepRunning = false hasOutOfOrderBlocks = false # Go over the full work queue and check for every work item if it is in # Received state and has the next blocks in line to be processed. for i in 0 ..< ctx.workQueue.len: let start = ctx.workQueue[i].startIndex # There should be at least 1 like this, namely the just received work item # that initiated this call. if ctx.workQueue[i].state == Received: if start == nextStartIndex: trace "Processing pending work item", number = start result = (i, ctx.persistWorkItem(ctx.workQueue[i])) # TODO: We can stop here on failure, but have to set # hasOutofORderBlocks. Is this always valid? nextStartIndex = ctx.finalizedBlock + 1 keepRunning = true break else: hasOutOfOrderBlocks = true ctx.hasOutOfOrderBlocks = hasOutOfOrderBlocks proc returnWorkItem(ctx: LegacySyncRef, workItem: int): ValidationResult = let wi = addr ctx.workQueue[workItem] let askedBlocks = wi.numBlocks.int let receivedBlocks = wi.headers.len let start {.used.} = wi.startIndex if askedBlocks == receivedBlocks: trace "Work item complete", start, askedBlocks, receivedBlocks if wi.startIndex != ctx.finalizedBlock + 1: trace "Blocks out of order", start, final = ctx.finalizedBlock ctx.hasOutOfOrderBlocks = true if ctx.hasOutOfOrderBlocks: let (index, validation) = ctx.persistPendingWorkItems() # Only report an error if it was this peer's work item that failed if validation == ValidationResult.Error and index == workItem: result = ValidationResult.Error # TODO: What about failures on other peers' work items? # In that case the peer will probably get disconnected on future erroneous # work items, but before this occurs, several more blocks (that will fail) # might get downloaded from this peer. This will delay the sync and this # should be improved. else: trace "Processing work item", number = wi.startIndex # Validation result needs to be returned so that higher up can be decided # to disconnect from this peer in case of error. result = ctx.persistWorkItem(wi[]) else: trace "Work item complete but we got fewer blocks than requested, so we're ditching the whole thing.", start, askedBlocks, receivedBlocks return ValidationResult.Error proc getBestBlockNumber(p: Peer): Future[BlockNumber] {.async.} = let request = BlocksRequest( startBlock: HashOrNum(isHash: true, hash: p.state(eth).bestBlockHash), maxResults: 1, skip: 0, reverse: true) trace trEthSendSendingGetBlockHeaders, peer=p, startBlock=request.startBlock.hash.toHex, max=request.maxResults let latestBlock = await p.getBlockHeaders(request) if latestBlock.isSome: if latestBlock.get.headers.len > 0: result = latestBlock.get.headers[0].blockNumber trace trEthRecvReceivedBlockHeaders, peer=p, count=latestBlock.get.headers.len, blockNumber=(if latestBlock.get.headers.len > 0: $result else: "missing") proc toRequest(workItem: WantedBlocks): BlocksRequest = if workItem.isHash: BlocksRequest( startBlock: HashOrNum(isHash: true, hash: workItem.hash), maxResults: workItem.numBlocks, skip: 0, reverse: false) else: BlocksRequest( startBlock: HashOrNum(isHash: false, number: workItem.startIndex), maxResults: workItem.numBlocks, skip: 0, reverse: false) type BodyHash = object txRoot: Hash256 uncleHash: Hash256 proc hash*(x: BodyHash): Hash = var h: Hash = 0 h = h !& hash(x.txRoot.data) h = h !& hash(x.uncleHash.data) result = !$h proc fetchBodies(ctx: LegacySyncRef, peer: Peer, workItemIdx: int, reqBodies: seq[bool]): Future[bool] {.async.} = template workItem: auto = ctx.workQueue[workItemIdx] var bodies = newSeqOfCap[BlockBody](workItem.headers.len) var hashes = newSeqOfCap[KeccakHash](maxBodiesFetch) doAssert(reqBodies.len == workItem.headers.len) template fetchBodies() = trace trEthSendSendingGetBlockBodies, peer, hashes=hashes.len let b = await peer.getBlockBodies(hashes) if b.isNone: raise newException(CatchableError, "Was not able to get the block bodies") let bodiesLen = b.get.blocks.len trace trEthRecvReceivedBlockBodies, peer, count=bodiesLen, requested=hashes.len if bodiesLen == 0: raise newException(CatchableError, "Zero block bodies received for request") elif bodiesLen < hashes.len: hashes.delete(0, bodiesLen - 1) elif bodiesLen == hashes.len: hashes.setLen(0) else: raise newException(CatchableError, "Too many block bodies received for request") bodies.add(b.get.blocks) var numRequest = 0 for i, h in workItem.headers: if reqBodies[i]: hashes.add(h.blockHash) inc numRequest if hashes.len == maxBodiesFetch: fetchBodies() while hashes.len != 0: fetchBodies() workItem.bodies = newSeqOfCap[BlockBody](workItem.headers.len) var bodyHashes = initTable[BodyHash, int]() for z, body in bodies: let bodyHash = BodyHash( txRoot: calcTxRoot(body.transactions), uncleHash: rlpHash(body.uncles)) bodyHashes[bodyHash] = z for i, req in reqBodies: if req: let bodyHash = BodyHash( txRoot: workItem.headers[i].txRoot, uncleHash: workItem.headers[i].ommersHash) let z = bodyHashes.getOrDefault(bodyHash, -1) if z == -1: error "header missing it's body", number=workItem.headers[i].blockNumber, hash=workItem.headers[i].blockHash.short return false workItem.bodies.add bodies[z] else: workItem.bodies.add BlockBody() return true proc obtainBlocksFromPeer(ctx: LegacySyncRef, peer: Peer) {.async.} = # Update our best block number try: if ctx.endBlockNumber <= ctx.finalizedBlock: # endBlockNumber need update let bestBlockNumber = await peer.getBestBlockNumber() if bestBlockNumber > ctx.endBlockNumber: trace "New sync end block number", number = bestBlockNumber ctx.endBlockNumber = bestBlockNumber except TransportError: debug "Transport got closed during obtainBlocksFromPeer" except CatchableError as e: debug "Exception in getBestBlockNumber()", exc = e.name, err = e.msg # no need to exit here, because the context might still have blocks to fetch # from this peer discard e while (let workItemIdx = ctx.availableWorkItem(); workItemIdx != -1 and peer.connectionState notin {Disconnecting, Disconnected}): template workItem: auto = ctx.workQueue[workItemIdx] workItem.state = Requested trace "Requesting block headers", start = workItem.startIndex, count = workItem.numBlocks, peer = peer.remote.node let request = toRequest(workItem) var dataReceived = true try: trace trEthSendSendingGetBlockHeaders, peer, startBlock=request.startBlock.number, max=request.maxResults, step=traceStep(request) let results = await peer.getBlockHeaders(request) if results.isSome: trace trEthRecvReceivedBlockHeaders, peer, count=results.get.headers.len, requested=request.maxResults shallowCopy(workItem.headers, results.get.headers) var reqBodies = newSeqOfCap[bool](workItem.headers.len) numRequest = 0 nextIndex = workItem.startIndex # skip requesting empty bodies for h in workItem.headers: if h.blockNumber != nextIndex: raise newException(CatchableError, "The block numbers are not in sequence. Not processing this workItem.") nextIndex = nextIndex + 1 let req = h.txRoot != EMPTY_ROOT_HASH or h.ommersHash != EMPTY_UNCLE_HASH reqBodies.add(req) if req: inc numRequest if numRequest > 0: dataReceived = dataReceived and await ctx.fetchBodies(peer, workItemIdx, reqBodies) else: # all bodies are empty workItem.bodies.setLen(workItem.headers.len) let peers = ctx.getPeers(peer) if peers.len > 0: var hashes = newSeqOfCap[NewBlockHashesAnnounce](workItem.headers.len) for h in workItem.headers: hashes.add NewBlockHashesAnnounce( hash: h.blockHash, number: h.blockNumber) trace "broadcast block hashes", numPeers=peers.len, numHashes=hashes.len await ctx.broadcastBlockHash(hashes, peers) # fetchBodies can fail dataReceived = dataReceived and true else: dataReceived = false except TransportError: debug "Transport got closed during obtainBlocksFromPeer", peer except CatchableError as e: # the success case sets `dataReceived`, so we can just fall back to the # failure path below. If we signal time-outs with exceptions such # failures will be easier to handle. debug "Exception in obtainBlocksFromPeer()", exc = e.name, err = e.msg, peer var giveUpOnPeer = false if dataReceived: trace "Finished obtaining blocks", peer, numBlocks=workItem.headers.len workItem.state = Received let res = ctx.returnWorkItem(workItemIdx) if res != ValidationResult.OK: trace "validation error" giveUpOnPeer = true else: giveUpOnPeer = true if giveUpOnPeer: workItem.state = Initial try: await peer.disconnect(SubprotocolReason) except CatchableError: discard ctx.handleLostPeer() break proc peersAgreeOnChain(a, b: Peer): Future[bool] {.async.} = # Returns true if one of the peers acknowledges existence of the best block # of another peer. var a = a b = b if a.state(eth).bestDifficulty < b.state(eth).bestDifficulty: swap(a, b) let request = BlocksRequest( startBlock: HashOrNum(isHash: true, hash: b.state(eth).bestBlockHash), maxResults: 1, skip: 0, reverse: true) trace trEthSendSendingGetBlockHeaders, peer=a, startBlock=request.startBlock.hash.toHex, max=request.maxResults var latestBlock: Option[blockHeadersObj] try: latestBlock = await a.getBlockHeaders(request) except TransportError: debug "Transport got closed during peersAgreeOnChain" return result = latestBlock.isSome and latestBlock.get.headers.len > 0 if latestBlock.isSome: let blockNumber {.used.} = if result: $latestBlock.get.headers[0].blockNumber else: "missing" trace trEthRecvReceivedBlockHeaders, peer=a, count=latestBlock.get.headers.len, blockNumber proc randomTrustedPeer(ctx: LegacySyncRef): Peer = var k = rand(ctx.trustedPeers.len - 1) var i = 0 for p in ctx.trustedPeers: result = p if i == k: return inc i proc startSyncWithPeerImpl(ctx: LegacySyncRef, peer: Peer) {.async.} = trace "Start sync", peer, trustedPeers = ctx.trustedPeers.len if ctx.trustedPeers.len >= minPeersToStartSync: # We have enough trusted peers. Validate new peer against trusted if await peersAgreeOnChain(peer, ctx.randomTrustedPeer()): ctx.trustedPeers.incl(peer) asyncSpawn ctx.obtainBlocksFromPeer(peer) elif ctx.trustedPeers.len == 0: # Assume the peer is trusted, but don't start sync until we reevaluate # it with more peers trace "Assume trusted peer", peer ctx.trustedPeers.incl(peer) else: # At this point we have some "trusted" candidates, but they are not # "trusted" enough. We evaluate `peer` against all other candidates. # If one of the candidates disagrees, we swap it for `peer`. If all # candidates agree, we add `peer` to trusted set. The peers in the set # will become "fully trusted" (and sync will start) when the set is big # enough var agreeScore = 0 disagreedPeer: Peer for tp in ctx.trustedPeers: if await peersAgreeOnChain(peer, tp): inc agreeScore else: disagreedPeer = tp let disagreeScore = ctx.trustedPeers.len - agreeScore if agreeScore == ctx.trustedPeers.len: ctx.trustedPeers.incl(peer) # The best possible outcome elif disagreeScore == 1: trace "Peer is no longer trusted for sync", peer ctx.trustedPeers.excl(disagreedPeer) ctx.trustedPeers.incl(peer) else: trace "Peer not trusted for sync", peer if ctx.trustedPeers.len == minPeersToStartSync: for p in ctx.trustedPeers: asyncSpawn ctx.obtainBlocksFromPeer(p) proc startSyncWithPeer(ctx: LegacySyncRef, peer: Peer) = try: let db = ctx.chain.db header = db.getBlockHeader(ctx.finalizedBlock) ourTD = db.getScore(header.blockHash) peerTD = peer.state(eth).bestDifficulty if peerTD <= ourTD: # do nothing if peer have same height if peerTD < ourTD: trace "Peer have lower TD, become recipient", peer, ourTD, peerTD asyncSpawn ctx.sendBlockOrHash(peer) return ctx.busyPeers.incl(peer) let f = ctx.startSyncWithPeerImpl(peer) f.callback = proc(data: pointer) {.gcsafe.} = if f.failed: if f.error of TransportError: debug "Transport got closed during startSyncWithPeer" else: error "startSyncWithPeer failed", msg = f.readError.msg, peer ctx.busyPeers.excl(peer) asyncSpawn f except TransportError: debug "Transport got closed during startSyncWithPeer" except CatchableError as e: debug "Exception in startSyncWithPeer()", exc = e.name, err = e.msg proc startObtainBlocks(ctx: LegacySyncRef, peer: Peer) = # simpler version of startSyncWithPeer try: ctx.busyPeers.incl(peer) let f = ctx.obtainBlocksFromPeer(peer) f.callback = proc(data: pointer) {.gcsafe.} = if f.failed: if f.error of TransportError: debug "Transport got closed during startObtainBlocks" else: error "startObtainBlocks failed", msg = f.readError.msg, peer ctx.busyPeers.excl(peer) asyncSpawn f except TransportError: debug "Transport got closed during startObtainBlocks" except CatchableError as e: debug "Exception in startObtainBlocks()", exc = e.name, err = e.msg proc onPeerConnected(ctx: LegacySyncRef, peer: Peer) = trace "New candidate for sync", peer ctx.startSyncWithPeer(peer) proc onPeerDisconnected(ctx: LegacySyncRef, p: Peer) = trace "peer disconnected ", peer = p ctx.trustedPeers.excl(p) ctx.busyPeers.excl(p) ctx.knownByPeer.del(p) # ------------------------------------------------------------------------------ # Public constructor/destructor # ------------------------------------------------------------------------------ proc new*(T: type LegacySyncRef; ethNode: EthereumNode; chain: ChainRef): T {.gcsafe, raises:[CatchableError].} = result = LegacySyncRef( # workQueue: n/a # endBlockNumber: n/a # hasOutOfOrderBlocks: n/a chain: chain, peerPool: ethNode.peerPool, trustedPeers: initHashSet[Peer]()) # finalizedBlock chain.com.syncCurrent = chain.db.getCanonicalHead().blockNumber proc start*(ctx: LegacySyncRef) = ## Code for the fast blockchain sync procedure: ## _ ## 1: for i in 1.. 0: # do nothing. busy peers will keep syncing # until new sync target reached trace "sync using busyPeers", len=ctx.busyPeers.len return if ctx.trustedPeers.len == 0: trace "sync with this peer" ctx.startObtainBlocks(peer) else: trace "sync with random peer" let peer = ctx.randomTrustedPeer() ctx.startSyncWithPeer(peer) proc handleNewBlock(ctx: LegacySyncRef, peer: Peer, blk: EthBlock, totalDifficulty: DifficultyInt) {. gcsafe, raises: [CatchableError].} = trace trEthRecvNewBlock, number=blk.header.blockNumber, hash=short(blk.header.blockHash) if ctx.lastCleanup - getTime() > CleanupInterval: ctx.cleanupKnownByPeer() # Don't send NEW_BLOCK announcement to peer that sent original new block message discard ctx.addToKnownByPeer(blk.header.blockHash, peer) if blk.header.blockNumber > ctx.finalizedBlock + 1.toBlockNumber: # If the block number exceeds one past our height we cannot validate it trace "NewBlock got block past our height", number=blk.header.blockNumber return if not ctx.validateHeader(blk.header): error "invalid header from peer", peer, hash=short(blk.header.blockHash) return # Send NEW_BLOCK to square root of total number of peers in pool # https://github.com/ethereum/devp2p/blob/master/caps/eth.md#block-propagation let numPeersToShareWith = sqrt(ctx.peerPool.len.float32).int peers = ctx.getPeers(peer) debug "num peers to share with", number=numPeersToShareWith, numPeers=peers.len if peers.len > 0 and numPeersToShareWith > 0: asyncSpawn ctx.broadcastBlock(blk, peers[0.. 0 and numPeersToShareWith > 0: # Send `NEW_BLOCK_HASHES` message for received block to all other peers asyncSpawn ctx.broadcastBlockHash(blk, peers[numPeersToShareWith..^1]) proc newBlockHashesHandler*(arg: pointer, peer: Peer, hashes: openArray[NewBlockHashesAnnounce]) = let ctx = cast[LegacySyncRef](arg) ctx.handleNewBlockHashes(peer, hashes) proc newBlockHandler*(arg: pointer, peer: Peer, blk: EthBlock, totalDifficulty: DifficultyInt) {. gcsafe, raises: [CatchableError].} = let ctx = cast[LegacySyncRef](arg) ctx.handleNewBlock(peer, blk, totalDifficulty) # End