nimbus-eth2/beacon_chain/sync_protocol.nim

306 lines
10 KiB
Nim

import
options, tables, sequtils, algorithm, sets, macros,
chronicles, chronos, ranges/bitranges,
spec/[datatypes, crypto, digest, helpers], eth/rlp,
beacon_node_types, eth2_network, beacon_chain_db, block_pool, time, ssz
type
ValidatorChangeLogEntry* = object
case kind*: ValidatorSetDeltaFlags
of Activation:
pubkey: ValidatorPubKey
else:
index: uint32
ValidatorSet = seq[Validator]
BeaconSyncState* = ref object
networkId*: uint8
chainId*: uint64
node*: BeaconNode
db*: BeaconChainDB
const
MaxRootsToRequest = 512
MaxHeadersToRequest = MaxRootsToRequest
MaxAncestorBlocksResponse = 256
func toHeader(b: BeaconBlock): BeaconBlockHeader =
BeaconBlockHeader(
slot: b.slot,
parent_root: b.parent_root,
state_root: b.state_root,
body_root: hash_tree_root(b.body),
signature: b.signature
)
proc fromHeaderAndBody(b: var BeaconBlock, h: BeaconBlockHeader, body: BeaconBlockBody) =
doAssert(hash_tree_root(body) == h.body_root)
b.slot = h.slot
b.parent_root = h.parent_root
b.state_root = h.state_root
b.body = body
b.signature = h.signature
proc importBlocks(node: BeaconNode,
blocks: openarray[BeaconBlock]) =
for blk in blocks:
node.onBeaconBlock(node, blk)
info "Forward sync imported blocks", len = blocks.len
proc mergeBlockHeadersAndBodies(headers: openarray[BeaconBlockHeader], bodies: openarray[BeaconBlockBody]): Option[seq[BeaconBlock]] =
if bodies.len != headers.len:
info "Cannot merge bodies and headers. Length mismatch.", bodies = bodies.len, headers = headers.len
return
var res: seq[BeaconBlock]
for i in 0 ..< headers.len:
if hash_tree_root(bodies[i]) != headers[i].body_root:
info "Block body is wrong for header"
return
res.setLen(res.len + 1)
res[^1].fromHeaderAndBody(headers[i], bodies[i])
some(res)
proc getBeaconBlocks*(peer: Peer, blockRoot: Eth2Digest, slot: Slot, maxBlocks, skipSlots: int, backward: uint8): Future[Option[seq[BeaconBlock]]] {.gcsafe, async.}
p2pProtocol BeaconSync(version = 1,
shortName = "bcs",
networkState = BeaconSyncState):
onPeerConnected do (peer: Peer):
let
protocolVersion = 1 # TODO: Spec doesn't specify this yet
node = peer.networkState.node
networkId = peer.networkState.networkId
chainId = peer.networkState.networkId
blockPool = node.blockPool
finalizedHead = blockPool.finalizedHead
headBlock = blockPool.head.blck
bestRoot = headBlock.root
bestSlot = headBlock.slot
latestFinalizedEpoch = finalizedHead.slot.slot_to_epoch()
let m = await peer.hello(networkId, chainId, finalizedHead.blck.root,
latestFinalizedEpoch, bestRoot, bestSlot,
timeout = 10.seconds)
if m.networkId != networkId:
await peer.disconnect(IrrelevantNetwork)
return
# TODO: onPeerConnected runs unconditionally for every connected peer, but we
# don't need to sync with everybody. The beacon node should detect a situation
# where it needs to sync and it should execute the sync algorithm with a certain
# number of randomly selected peers. The algorithm itself must be extracted in a proc.
try:
debug "Peer connected. Initiating sync", peer, bestSlot, remoteBestSlot = m.bestSlot
let bestDiff = cmp((latestFinalizedEpoch, bestSlot), (m.latestFinalizedEpoch, m.bestSlot))
if bestDiff >= 0:
# Nothing to do?
debug "Nothing to sync", peer
else:
# TODO: Check for WEAK_SUBJECTIVITY_PERIOD difference and terminate the
# connection if it's too big.
var s = bestSlot + 1
while s <= m.bestSlot:
debug "Waiting for block headers", fromPeer = peer, remoteBestSlot = m.bestSlot, peer
let headersLeft = int(m.bestSlot - s)
let blocks = await peer.getBeaconBlocks(bestRoot, s, min(headersLeft, MaxHeadersToRequest), 0, 0)
if blocks.isSome:
if blocks.get.len == 0:
info "Got 0 blocks while syncing", peer
break
node.importBlocks(blocks.get)
let lastSlot = blocks.get[^1].slot
if lastSlot <= s:
info "Slot did not advance during sync", peer
break
s = lastSlot + 1
else:
break
except CatchableError:
warn "Failed to sync with peer", peer, err = getCurrentExceptionMsg()
handshake:
proc hello(
peer: Peer,
networkId: uint8,
chainId: uint64,
latestFinalizedRoot: Eth2Digest,
latestFinalizedEpoch: Epoch,
bestRoot: Eth2Digest,
bestSlot: Slot)
proc goodbye(peer: Peer, reason: DisconnectionReason)
requestResponse:
proc getStatus(
peer: Peer,
sha: Eth2Digest,
userAgent: string,
timestamp: uint64) =
# TODO: How should this be implemented?
# https://github.com/ethereum/eth2.0-specs/blob/dev/specs/networking/rpc-interface.md#get-status
await response.send(sha, userAgent, timestamp)
proc status(peer: Peer, sha: Eth2Digest, userAgent: string, timestamp: uint64)
nextId 10
requestResponse:
proc getBeaconBlockRoots(
peer: Peer,
fromSlot: Slot,
maxRoots: int) =
let maxRoots = min(MaxRootsToRequest, maxRoots)
var s = fromSlot
var roots = newSeqOfCap[(Eth2Digest, Slot)](maxRoots)
let blockPool = peer.networkState.node.blockPool
let maxSlot = blockPool.head.blck.slot
while s <= maxSlot:
for r in blockPool.blockRootsForSlot(s):
roots.add((r, s))
if roots.len == maxRoots: break
s += 1
await response.send(roots)
proc beaconBlockRoots(peer: Peer, roots: openarray[(Eth2Digest, Slot)])
requestResponse:
proc getBeaconBlockHeaders(
peer: Peer,
blockRoot: Eth2Digest,
slot: Slot,
maxHeaders: int,
skipSlots: int,
backward: uint8) =
let maxHeaders = min(MaxHeadersToRequest, maxHeaders)
var headers: seq[BeaconBlockHeader]
let db = peer.networkState.db
if backward != 0:
# TODO: implement skipSlots
var blockRoot = blockRoot
if slot != GENESIS_SLOT:
# TODO: Get block from the best chain by slot
# blockRoot = ...
discard
let blockPool = peer.networkState.node.blockPool
var br = blockPool.getRef(blockRoot)
var blockRefs = newSeqOfCap[BlockRef](maxHeaders)
while not br.isNil:
blockRefs.add(br)
if blockRefs.len == maxHeaders:
break
br = br.parent
headers = newSeqOfCap[BeaconBlockHeader](blockRefs.len)
for i in blockRefs.high .. 0:
headers.add(blockPool.get(blockRefs[i]).data.toHeader)
else:
# TODO: This branch has to be revisited and possibly somehow merged with the
# branch above once we can traverse the best chain forward
# TODO: implement skipSlots
headers = newSeqOfCap[BeaconBlockHeader](maxHeaders)
var s = slot
let blockPool = peer.networkState.node.blockPool
let maxSlot = blockPool.head.blck.slot
while s <= maxSlot:
for r in blockPool.blockRootsForSlot(s):
headers.add(db.getBlock(r).get().toHeader)
if headers.len == maxHeaders: break
s += 1
await response.send(headers)
proc beaconBlockHeaders(peer: Peer, blockHeaders: openarray[BeaconBlockHeader])
# TODO move this at the bottom, because it's not in the spec yet, but it will
# consume a `method_id`
requestResponse:
proc getAncestorBlocks(
peer: Peer,
needed: openarray[FetchRecord]) =
var resp = newSeqOfCap[BeaconBlock](needed.len)
let db = peer.networkState.db
var neededRoots = initSet[Eth2Digest]()
for rec in needed: neededRoots.incl(rec.root)
for rec in needed:
if (var blck = db.getBlock(rec.root); blck.isSome()):
# TODO validate historySlots
let firstSlot = blck.get().slot - rec.historySlots
for i in 0..<rec.historySlots.int:
resp.add(blck.get())
if resp.len >= MaxAncestorBlocksResponse:
break
if blck.get().parent_root in neededRoots:
# Don't send duplicate blocks, if neededRoots has roots that are
# in the same chain
break
if (blck = db.getBlock(blck.get().parent_root);
blck.isNone() or blck.get().slot < firstSlot):
break
if resp.len >= MaxAncestorBlocksResponse:
break
await response.send(resp)
proc ancestorBlocks(peer: Peer, blocks: openarray[BeaconBlock])
requestResponse:
proc getBeaconBlockBodies(
peer: Peer,
blockRoots: openarray[Eth2Digest]) =
# TODO: Validate blockRoots.len
var bodies = newSeqOfCap[BeaconBlockBody](blockRoots.len)
let db = peer.networkState.db
for r in blockRoots:
if (let blk = db.getBlock(r); blk.isSome):
bodies.add(blk.get().body)
else:
bodies.setLen(bodies.len + 1) # According to wire spec. Pad with zero body.
await response.send(bodies)
proc beaconBlockBodies(
peer: Peer,
blockBodies: openarray[BeaconBlockBody])
proc getBeaconBlocks*(peer: Peer, blockRoot: Eth2Digest, slot: Slot, maxBlocks, skipSlots: int, backward: uint8): Future[Option[seq[BeaconBlock]]] {.async.} =
## Retrieve block headers and block bodies from the remote peer, merge them into blocks.
assert(maxBlocks <= MaxHeadersToRequest)
let headersResp = await peer.getBeaconBlockHeaders(blockRoot, slot, maxBlocks, skipSlots, backward)
if headersResp.isNone: return
let headers = headersResp.get.blockHeaders
if headers.len == 0:
info "Peer has no headers", peer
var res: seq[BeaconBlock]
return some(res)
let bodiesRequest = headers.mapIt(signing_root(it))
debug "Block headers received. Requesting block bodies", peer
let bodiesResp = await peer.getBeaconBlockBodies(bodiesRequest)
if bodiesResp.isNone:
info "Did not receive bodies", peer
return
result = mergeBlockHeadersAndBodies(headers, bodiesResp.get.blockBodies)
# If result.isNone: disconnect with BreachOfProtocol?