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# 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,
body: BlockBody,
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 = 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, body)
if res.isErr:
trace "validate withdrawals error",
msg=res.error
return false
res = com.validateEip4844Header(header, parentHeader, body.transactions)
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
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:
## <https://github.com/ethereum/wiki/wiki/Parallel-Block-Downloads>_
## <https://github.com/ethereum/go-ethereum/pull/1889__
try:
var blockHash: Hash256
let
db = ctx.chain.db
com = ctx.chain.com
if not db.getBlockHash(ctx.finalizedBlock, blockHash):
debug "FastSync.start: Failed to get blockHash",
number=ctx.finalizedBlock
return
if com.consensus == ConsensusType.POS:
debug "Fast sync is disabled after POS merge"
return
ctx.chain.com.syncStart = ctx.finalizedBlock
info "Fast Sync: start sync from",
number=ctx.chain.com.syncStart,
hash=blockHash
except CatchableError as e:
debug "Exception in FastSync.start()",
exc = e.name, err = e.msg
var po = PeerObserver(
onPeerConnected:
proc(p: Peer) {.gcsafe.} =
ctx.onPeerConnected(p),
onPeerDisconnected:
proc(p: Peer) {.gcsafe.} =
ctx.onPeerDisconnected(p))
po.setProtocol eth
ctx.peerPool.addObserver(ctx, po)
# ------------------------------------------------------------------------------
# Public procs: eth wire protocol handlers
# ------------------------------------------------------------------------------
proc handleNewBlockHashes(ctx: LegacySyncRef,
peer: Peer,
hashes: openArray[NewBlockHashesAnnounce]) =
trace trEthRecvNewBlockHashes,
numHash=hashes.len
if hashes.len == 0:
return
var number = hashes[0].number
if hashes.len > 1:
for i in 1..<hashes.len:
let val = hashes[i]
if val.number != number + 1.toBlockNumber:
error "Found a gap in block hashes"
return
number = val.number
number = hashes[^1].number
if number <= ctx.endBlockNumber:
trace "Will not set new synctarget",
newSyncHeight=number,
endBlockNumber=ctx.endBlockNumber,
peer
return
# don't send back hashes to this peer
for val in hashes:
discard ctx.addToKnownByPeer(val.hash, peer)
# set new sync target, + 1'u means including last block
let numBlocks = (number - hashes[0].number).truncate(uint) + 1'u
ctx.appendWorkItem(hashes[0].hash, hashes[0].number, numBlocks)
ctx.endBlockNumber = number
trace "New sync target height", number
if ctx.busyPeers.len > 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
let body = BlockBody(
transactions: blk.txs,
uncles: blk.uncles,
withdrawals: blk.withdrawals
)
if not ctx.validateHeader(blk.header, body):
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..<numPeersToShareWith])
var parentHash: Hash256
if not ctx.chain.db.getBlockHash(ctx.finalizedBlock, parentHash):
error "failed to get parent hash",
number=ctx.finalizedBlock
return
if parentHash == blk.header.parentHash:
# If new block is child of current chain tip, insert new block into chain
let body = BlockBody(
transactions: blk.txs,
uncles: blk.uncles
)
let res = ctx.chain.persistBlocks([blk.header], [body])
# Check if new sync target height can be set
if res == ValidationResult.OK:
ctx.endBlockNumber = blk.header.blockNumber
ctx.finalizedBlock = blk.header.blockNumber
else:
# Call handleNewBlockHashes to retrieve all blocks between chain tip and new block
let newSyncHeight = NewBlockHashesAnnounce(
number: blk.header.blockNumber,
hash: blk.header.blockHash
)
ctx.handleNewBlockHashes(peer, [newSyncHeight])
if peers.len > 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
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