nim-libp2p-dht/codexdht/private/eth/p2p/discoveryv5/protocol.nim

1217 lines
45 KiB
Nim

# codex-dht - Codex DHT
# 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.
## Node Discovery Protocol v5
##
## Node discovery protocol implementation as per specification:
## https://github.com/ethereum/devp2p/blob/master/discv5/discv5.md
##
## This node discovery protocol implementation uses the same underlying
## implementation of routing table as is also used for the discovery v4
## implementation, which is the same or similar as the one described in the
## original Kademlia paper:
## https://pdos.csail.mit.edu/~petar/papers/maymounkov-kademlia-lncs.pdf
##
## This might not be the most optimal implementation for the node discovery
## protocol v5. Why?
##
## The Kademlia paper describes an implementation that starts off from one
## k-bucket, and keeps splitting the bucket as more nodes are discovered and
## added. The bucket splits only on the part of the binary tree where our own
## node its id belongs too (same prefix). Resulting eventually in a k-bucket per
## logarithmic distance (log base2 distance). Well, not really, as nodes with
## ids in the closer distance ranges will never be found. And because of this an
## optimisation is done where buckets will also split sometimes even if the
## nodes own id does not have the same prefix (this is to avoid creating highly
## unbalanced branches which would require longer lookups).
##
## Now, some implementations take a more simplified approach. They just create
## directly a bucket for each possible logarithmic distance (e.g. here 1->256).
## Some implementations also don't create buckets with logarithmic distance
## lower than a certain value (e.g. only 1/15th of the highest buckets),
## because the closer to the node (the lower the distance), the less chance
## there is to still find nodes.
##
## The discovery protocol v4 its `FindNode` call will request the k closest
## nodes. As does original Kademlia. This effectively puts the work at the node
## that gets the request. This node will have to check its buckets and gather
## the closest. Some implementations go over all the nodes in all the buckets
## for this (e.g. go-ethereum discovery v4). However, in our bucket splitting
## approach, this search is improved.
##
## In the discovery protocol v5 the `FindNode` call is changed and now the
## logarithmic distance is passed as parameter instead of the NodeId. And only
## nodes that match that logarithmic distance are allowed to be returned.
## This change was made to not put the trust at the requested node for selecting
## the closest nodes. To counter a possible (mistaken) difference in
## implementation, but more importantly for security reasons. See also:
## https://github.com/ethereum/devp2p/blob/master/discv5/discv5-rationale.md#115-guard-against-kademlia-implementation-flaws
##
## The result is that in an implementation which just stores buckets per
## logarithmic distance, it simply needs to return the right bucket. In our
## split-bucket implementation, this cannot be done as such and thus the closest
## neighbors search is still done. And to do this, a reverse calculation of an
## id at given logarithmic distance is needed (which is why there is the
## `idAtDistance` proc). Next, nodes with invalid distances need to be filtered
## out to be compliant to the specification. This can most likely get further
## optimized, but it sounds likely better to switch away from the split-bucket
## approach. I believe that the main benefit it has is improved lookups
## (due to no unbalanced branches), and it looks like this will be negated by
## limiting the returned nodes to only the ones of the requested logarithmic
## distance for the `FindNode` call.
## This `FindNode` change in discovery v5 will also have an effect on the
## efficiency of the network. Work will be moved from the receiver of
## `FindNodes` to the requester. But this also means more network traffic,
## as less nodes will potentially be passed around per `FindNode` call, and thus
## more requests will be needed for a lookup (adding bandwidth and latency).
## This might be a concern for mobile devices.
{.push raises: [Defect].}
import
std/[tables, sets, options, math, sequtils, algorithm, strutils],
stew/shims/net as stewNet,
json_serialization/std/net,
stew/[base64, endians2, results],
pkg/[chronicles, chronicles/chronos_tools],
pkg/chronos,
pkg/stint,
pkg/bearssl/rand,
pkg/metrics
import "."/[
messages,
messages_encoding,
node,
routing_table,
spr,
random2,
ip_vote,
nodes_verification,
providers,
transport]
import nimcrypto except toHex
export options, results, node, spr, providers
declareCounter dht_message_requests_outgoing,
"Discovery protocol outgoing message requests", labels = ["response"]
declareCounter dht_message_requests_incoming,
"Discovery protocol incoming message requests", labels = ["response"]
declareCounter dht_unsolicited_messages,
"Discovery protocol unsolicited or timed-out messages"
declareCounter dht_enr_auto_update,
"Amount of discovery IP:port address SPR auto updates"
logScope:
topics = "discv5"
const
Alpha = 3 ## Kademlia concurrency factor
LookupRequestLimit = 3 ## Amount of distances requested in a single Findnode
## message for a lookup or query
FindNodeResultLimit = 16 ## Maximum amount of SPRs in the total Nodes messages
FindNodeFastResultLimit = 6 ## Maximum amount of SPRs in response to findNodeFast
## that will be processed
MaxNodesPerMessage = 3 ## Maximum amount of SPRs per individual Nodes message
RefreshInterval = 5.minutes ## Interval of launching a random query to
## refresh the routing table.
RevalidateMin = 5000
RevalidateMax = 10000 ## Revalidation of a peer is done between min and max milliseconds.
## value in milliseconds
IpMajorityInterval = 5.minutes ## Interval for checking the latest IP:Port
DebugPrintInterval = 5.minutes ## Interval to print neighborhood with stats
## majority and updating this when SPR auto update is set.
InitialLookups = 1 ## Amount of lookups done when populating the routing table
ResponseTimeout* = 1.seconds ## timeout for the response of a request-response
MaxProvidersEntries* = 1_000_000 # one million records
MaxProvidersPerEntry* = 20 # providers per entry
## call
FindnodeSeenThreshold = 1.0 ## threshold used as findnode response filter
LookupSeenThreshold = 0.0 ## threshold used for lookup nodeset selection
QuerySeenThreshold = 0.0 ## threshold used for query nodeset selection
NoreplyRemoveThreshold = 0.5 ## remove node on no reply if 'seen' is below this value
func shortLog*(record: SignedPeerRecord): string =
## Returns compact string representation of ``SignedPeerRecord``.
##
result =
"peerId: " & record.data.peerId.shortLog & ", " &
"seqNo: " & $record.data.seqNo & ", " &
"addresses: " & record.data.addresses.mapIt($it.address).join(", ")
func shortLog*(records: seq[SignedPeerRecord]): string =
## Returns compact string representation of a sequence of
## ``SignedPeerRecord``.
##
for r in records:
result &= "provider: " & r.shortLog
chronicles.formatIt(SignedPeerRecord): shortLog(it)
chronicles.formatIt(seq[SignedPeerRecord]): shortLog(it)
type
DiscoveryConfig* = object
tableIpLimits*: TableIpLimits
bitsPerHop*: int
Protocol* = ref object
localNode*: Node
privateKey: PrivateKey
transport*: Transport[Protocol] # exported for tests
routingTable*: RoutingTable
awaitedMessages: Table[(NodeId, RequestId), Future[Option[Message]]]
refreshLoop: Future[void]
revalidateLoop: Future[void]
ipMajorityLoop: Future[void]
debugPrintLoop: Future[void]
lastLookup: chronos.Moment
bootstrapRecords*: seq[SignedPeerRecord]
ipVote: IpVote
enrAutoUpdate: bool
talkProtocols*: Table[seq[byte], TalkProtocol] # TODO: Table is a bit of
rng*: ref HmacDrbgContext
providers: ProvidersManager
TalkProtocolHandler* = proc(p: TalkProtocol, request: seq[byte], fromId: NodeId, fromUdpAddress: Address): seq[byte]
{.gcsafe, raises: [Defect].}
TalkProtocol* = ref object of RootObj
protocolHandler*: TalkProtocolHandler
DiscResult*[T] = Result[T, cstring]
func `$`*(p: Protocol): string =
$p.localNode.id
const
defaultDiscoveryConfig* = DiscoveryConfig(
tableIpLimits: DefaultTableIpLimits,
bitsPerHop: DefaultBitsPerHop)
proc addNode*(d: Protocol, node: Node): bool =
## Add `Node` to discovery routing table.
##
## Returns true only when `Node` was added as a new entry to a bucket in the
## routing table.
if d.routingTable.addNode(node) == Added:
return true
else:
return false
proc addNode*(d: Protocol, r: SignedPeerRecord): bool =
## Add `Node` from a `SignedPeerRecord` to discovery routing table.
##
## Returns false only if no valid `Node` can be created from the `SignedPeerRecord` or
## on the conditions of `addNode` from a `Node`.
let node = newNode(r)
if node.isOk():
return d.addNode(node[])
else:
return false
proc addNode*(d: Protocol, spr: SprUri): bool =
## Add `Node` from a SPR URI to discovery routing table.
##
## Returns false if no valid SPR URI, or on the conditions of `addNode` from
## an `SignedPeerRecord`.
try:
var r: SignedPeerRecord
let res = r.fromURI(spr)
if res:
return d.addNode(r)
except Base64Error as e:
error "Base64 error decoding SPR URI", error = e.msg
return false
proc getNode*(d: Protocol, id: NodeId): Option[Node] =
## Get the node with id from the routing table.
d.routingTable.getNode(id)
proc randomNodes*(d: Protocol, maxAmount: int): seq[Node] =
## Get a `maxAmount` of random nodes from the local routing table.
d.routingTable.randomNodes(maxAmount)
proc randomNodes*(d: Protocol, maxAmount: int,
pred: proc(x: Node): bool {.gcsafe, noSideEffect.}): seq[Node] =
## Get a `maxAmount` of random nodes from the local routing table with the
## `pred` predicate function applied as filter on the nodes selected.
d.routingTable.randomNodes(maxAmount, pred)
proc randomNodes*(d: Protocol, maxAmount: int,
enrField: (string, seq[byte])): seq[Node] =
## Get a `maxAmount` of random nodes from the local routing table. The
## the nodes selected are filtered by provided `enrField`.
d.randomNodes(maxAmount, proc(x: Node): bool = x.record.contains(enrField))
proc neighbours*(d: Protocol, id: NodeId, k: int = BUCKET_SIZE,
seenThreshold = 0.0): seq[Node] =
## Return up to k neighbours (closest node ids) of the given node id.
d.routingTable.neighbours(id, k, seenThreshold)
proc neighboursAtDistances*(d: Protocol, distances: seq[uint16],
k: int = BUCKET_SIZE, seenThreshold = 0.0): seq[Node] =
## Return up to k neighbours (closest node ids) at given distances.
d.routingTable.neighboursAtDistances(distances, k, seenThreshold)
proc nodesDiscovered*(d: Protocol): int = d.routingTable.len
func privKey*(d: Protocol): lent PrivateKey =
d.privateKey
func getRecord*(d: Protocol): SignedPeerRecord =
## Get the SPR of the local node.
d.localNode.record
proc updateRecord*(
d: Protocol,
spr: Option[SignedPeerRecord] = SignedPeerRecord.none): DiscResult[void] =
## Update the ENR of the local node with provided `enrFields` k:v pairs.
##
if spr.isSome:
let
newSpr = spr.get()
seqNo = d.localNode.record.seqNum
info "Updated discovery SPR", uri = newSpr.toURI(), newSpr = newSpr.data
d.localNode.record = newSpr
d.localNode.record.data.seqNo = seqNo
? d.localNode.record.incSeqNo(d.privateKey)
# TODO: Would it make sense to actively ping ("broadcast") to all the peers
# we stored a handshake with in order to get that ENR updated?
ok()
proc sendResponse(d: Protocol, dstId: NodeId, dstAddr: Address,
message: SomeMessage, reqId: RequestId) =
## send Response using the specifid reqId
d.transport.sendMessage(dstId, dstAddr, encodeMessage(message, reqId))
proc sendNodes(d: Protocol, toId: NodeId, toAddr: Address, reqId: RequestId,
nodes: openArray[Node]) =
proc sendNodes(d: Protocol, toId: NodeId, toAddr: Address,
message: NodesMessage, reqId: RequestId) {.nimcall.} =
trace "Respond message packet", dstId = toId, address = toAddr,
kind = MessageKind.nodes
d.sendResponse(toId, toAddr, message, reqId)
if nodes.len == 0:
# In case of 0 nodes, a reply is still needed
d.sendNodes(toId, toAddr, NodesMessage(total: 1, sprs: @[]), reqId)
return
var message: NodesMessage
# TODO: Do the total calculation based on the max UDP packet size we want to
# send and the SPR size of all (max 16) nodes.
# Which UDP packet size to take? 1280? 576?
message.total = ceil(nodes.len / MaxNodesPerMessage).uint32
for i in 0 ..< nodes.len:
message.sprs.add(nodes[i].record)
if message.sprs.len == MaxNodesPerMessage:
d.sendNodes(toId, toAddr, message, reqId)
message.sprs.setLen(0)
if message.sprs.len != 0:
d.sendNodes(toId, toAddr, message, reqId)
proc handlePing(d: Protocol, fromId: NodeId, fromAddr: Address,
ping: PingMessage, reqId: RequestId) =
let pong = PongMessage(sprSeq: d.localNode.record.seqNum, ip: fromAddr.ip,
port: fromAddr.port.uint16)
trace "Respond message packet", dstId = fromId, address = fromAddr,
kind = MessageKind.pong
d.sendResponse(fromId, fromAddr, pong, reqId)
proc handleFindNode(d: Protocol, fromId: NodeId, fromAddr: Address,
fn: FindNodeMessage, reqId: RequestId) =
if fn.distances.len == 0:
d.sendNodes(fromId, fromAddr, reqId, [])
elif fn.distances.contains(0):
# A request for our own record.
# It would be a weird request if there are more distances next to 0
# requested, so in this case lets just pass only our own. TODO: OK?
d.sendNodes(fromId, fromAddr, reqId, [d.localNode])
else:
# TODO: Still deduplicate also?
if fn.distances.all(proc (x: uint16): bool = return x <= 256):
d.sendNodes(fromId, fromAddr, reqId,
d.routingTable.neighboursAtDistances(fn.distances, FindNodeResultLimit, FindnodeSeenThreshold))
else:
# At least one invalid distance, but the polite node we are, still respond
# with empty nodes.
d.sendNodes(fromId, fromAddr, reqId, [])
proc handleFindNodeFast(d: Protocol, fromId: NodeId, fromAddr: Address,
fnf: FindNodeFastMessage, reqId: RequestId) =
d.sendNodes(fromId, fromAddr, reqId,
d.routingTable.neighbours(fnf.target, FindNodeFastResultLimit, FindnodeSeenThreshold))
# TODO: if known, maybe we should add exact target even if not yet "seen"
proc handleTalkReq(d: Protocol, fromId: NodeId, fromAddr: Address,
talkreq: TalkReqMessage, reqId: RequestId) =
let talkProtocol = d.talkProtocols.getOrDefault(talkreq.protocol)
let talkresp =
if talkProtocol.isNil() or talkProtocol.protocolHandler.isNil():
# Protocol identifier that is not registered and thus not supported. An
# empty response is send as per specification.
TalkRespMessage(response: @[])
else:
TalkRespMessage(response: talkProtocol.protocolHandler(talkProtocol,
talkreq.request, fromId, fromAddr))
trace "Respond message packet", dstId = fromId, address = fromAddr,
kind = MessageKind.talkresp
d.sendResponse(fromId, fromAddr, talkresp, reqId)
proc addProviderLocal(p: Protocol, cId: NodeId, prov: SignedPeerRecord) {.async.} =
trace "adding provider to local db", n = p.localNode, cId, prov
if (let res = (await p.providers.add(cId, prov)); res.isErr):
trace "Unable to add provider", cid, peerId = prov.data.peerId
proc handleAddProvider(
d: Protocol,
fromId: NodeId,
fromAddr: Address,
addProvider: AddProviderMessage,
reqId: RequestId) =
asyncSpawn d.addProviderLocal(addProvider.cId, addProvider.prov)
proc handleGetProviders(
d: Protocol,
fromId: NodeId,
fromAddr: Address,
getProviders: GetProvidersMessage,
reqId: RequestId) {.async.} =
#TODO: add checks, add signed version
let
provs = await d.providers.get(getProviders.cId)
if provs.isErr:
trace "Unable to get providers", cid = getProviders.cId, err = provs.error.msg
return
##TODO: handle multiple messages
let response = ProvidersMessage(total: 1, provs: provs.get)
d.sendResponse(fromId, fromAddr, response, reqId)
proc handleMessage(d: Protocol, srcId: NodeId, fromAddr: Address,
message: Message) =
case message.kind
of ping:
dht_message_requests_incoming.inc()
d.handlePing(srcId, fromAddr, message.ping, message.reqId)
of findNode:
dht_message_requests_incoming.inc()
d.handleFindNode(srcId, fromAddr, message.findNode, message.reqId)
of findNodeFast:
dht_message_requests_incoming.inc()
d.handleFindNodeFast(srcId, fromAddr, message.findNodeFast, message.reqId)
of talkReq:
dht_message_requests_incoming.inc()
d.handleTalkReq(srcId, fromAddr, message.talkReq, message.reqId)
of addProvider:
dht_message_requests_incoming.inc()
dht_message_requests_incoming.inc(labelValues = ["no_response"])
d.handleAddProvider(srcId, fromAddr, message.addProvider, message.reqId)
of getProviders:
dht_message_requests_incoming.inc()
asyncSpawn d.handleGetProviders(srcId, fromAddr, message.getProviders, message.reqId)
of regTopic, topicQuery:
dht_message_requests_incoming.inc()
dht_message_requests_incoming.inc(labelValues = ["no_response"])
trace "Received unimplemented message kind", kind = message.kind,
origin = fromAddr
else:
var waiter: Future[Option[Message]]
if d.awaitedMessages.take((srcId, message.reqId), waiter):
waiter.complete(some(message))
else:
dht_unsolicited_messages.inc()
trace "Timed out or unrequested message", kind = message.kind,
origin = fromAddr
proc registerTalkProtocol*(d: Protocol, protocolId: seq[byte],
protocol: TalkProtocol): DiscResult[void] =
# Currently allow only for one handler per talk protocol.
if d.talkProtocols.hasKeyOrPut(protocolId, protocol):
err("Protocol identifier already registered")
else:
ok()
proc replaceNode(d: Protocol, n: Node, forceRemoveBelow = 1.0) =
if n.record notin d.bootstrapRecords:
d.routingTable.replaceNode(n, forceRemoveBelow)
else:
# For now we never remove bootstrap nodes. It might make sense to actually
# do so and to retry them only in case we drop to a really low amount of
# peers in the routing table.
debug "Message request to bootstrap node failed", src=d.localNode, dst=n
proc sendRequest*[T: SomeMessage](d: Protocol, toNode: Node, m: T,
reqId: RequestId) =
doAssert(toNode.address.isSome())
let
message = encodeMessage(m, reqId)
trace "Send message packet", dstId = toNode.id,
address = toNode.address, kind = messageKind(T)
dht_message_requests_outgoing.inc()
d.transport.sendMessage(toNode, message)
proc waitResponse*[T: SomeMessage](d: Protocol, node: Node, msg: T):
Future[Option[Message]] =
let reqId = RequestId.init(d.rng[])
result = d.waitMessage(node, reqId)
sendRequest(d, node, msg, reqId)
proc waitMessage(d: Protocol, fromNode: Node, reqId: RequestId, timeout = ResponseTimeout):
Future[Option[Message]] =
result = newFuture[Option[Message]]("waitMessage")
let res = result
let key = (fromNode.id, reqId)
sleepAsync(timeout).addCallback() do(data: pointer):
d.awaitedMessages.del(key)
if not res.finished:
res.complete(none(Message))
d.awaitedMessages[key] = result
proc waitNodeResponses*[T: SomeMessage](d: Protocol, node: Node, msg: T):
Future[DiscResult[seq[SignedPeerRecord]]] =
let reqId = RequestId.init(d.rng[])
result = d.waitNodes(node, reqId)
sendRequest(d, node, msg, reqId)
proc waitNodes(d: Protocol, fromNode: Node, reqId: RequestId):
Future[DiscResult[seq[SignedPeerRecord]]] {.async.} =
## Wait for one or more nodes replies.
##
## The first reply will hold the total number of replies expected, and based
## on that, more replies will be awaited.
## If one reply is lost here (timed out), others are ignored too.
## Same counts for out of order receival.
let startTime = Moment.now()
var op = await d.waitMessage(fromNode, reqId)
if op.isSome:
if op.get.kind == MessageKind.nodes:
var res = op.get.nodes.sprs
let
total = op.get.nodes.total
firstTime = Moment.now()
rtt = firstTime - startTime
# trace "nodes RTT:", rtt, node = fromNode
fromNode.registerRtt(rtt)
for i in 1 ..< total:
op = await d.waitMessage(fromNode, reqId)
if op.isSome and op.get.kind == MessageKind.nodes:
res.add(op.get.nodes.sprs)
# Estimate bandwidth based on UDP packet train received, assuming these were
# released fast and spaced in time by bandwidth bottleneck. This is just a rough
# packet-pair based estimate, far from being perfect.
# TODO: get message size from lower layer for better bandwidth estimate
# TODO: get better reception timestamp from lower layers
let
deltaT = Moment.now() - firstTime
bwBps = 500.0 * 8.0 / (deltaT.nanoseconds.float / i.float / 1e9)
# trace "bw estimate:", deltaT = deltaT, i, bw_mbps = bwBps / 1e6, node = fromNode
fromNode.registerBw(bwBps)
else:
# No error on this as we received some nodes.
break
return ok(res)
else:
dht_message_requests_outgoing.inc(labelValues = ["invalid_response"])
return err("Invalid response to find node message")
else:
dht_message_requests_outgoing.inc(labelValues = ["no_response"])
return err("Nodes message not received in time")
proc ping*(d: Protocol, toNode: Node):
Future[DiscResult[PongMessage]] {.async.} =
## Send a discovery ping message.
##
## Returns the received pong message or an error.
let
msg = PingMessage(sprSeq: d.localNode.record.seqNum)
startTime = Moment.now()
resp = await d.waitResponse(toNode, msg)
rtt = Moment.now() - startTime
# trace "ping RTT:", rtt, node = toNode
toNode.registerRtt(rtt)
d.routingTable.setJustSeen(toNode, resp.isSome())
if resp.isSome():
if resp.get().kind == pong:
return ok(resp.get().pong)
else:
d.replaceNode(toNode)
dht_message_requests_outgoing.inc(labelValues = ["invalid_response"])
return err("Invalid response to ping message")
else:
# A ping (or the pong) was lost, what should we do? Previous implementation called
# d.replaceNode(toNode) immediately, which removed the node. This is too aggressive,
# especially if we have a temporary network outage. Although bootstrap nodes are protected
# from being removed, everything else would slowly be removed.
d.replaceNode(toNode, NoreplyRemoveThreshold)
dht_message_requests_outgoing.inc(labelValues = ["no_response"])
return err("Pong message not received in time")
proc findNode*(d: Protocol, toNode: Node, distances: seq[uint16]):
Future[DiscResult[seq[Node]]] {.async.} =
## Send a getNeighbours message.
##
## Returns the received nodes or an error.
## Received SPRs are already validated and converted to `Node`.
let
msg = FindNodeMessage(distances: distances)
nodes = await d.waitNodeResponses(toNode, msg)
d.routingTable.setJustSeen(toNode, nodes.isOk)
if nodes.isOk:
let res = verifyNodesRecords(nodes.get(), toNode, FindNodeResultLimit, distances)
return ok(res)
else:
trace "findNode nodes not OK."
d.replaceNode(toNode)
return err(nodes.error)
proc findNodeFast*(d: Protocol, toNode: Node, target: NodeId):
Future[DiscResult[seq[Node]]] {.async.} =
## Send a findNode message.
##
## Returns the received nodes or an error.
## Received SPRs are already validated and converted to `Node`.
let
msg = FindNodeFastMessage(target: target)
nodes = await d.waitNodeResponses(toNode, msg)
d.routingTable.setJustSeen(toNode, nodes.isOk)
if nodes.isOk:
let res = verifyNodesRecords(nodes.get(), toNode, FindNodeFastResultLimit)
return ok(res)
else:
d.replaceNode(toNode)
return err(nodes.error)
proc talkReq*(d: Protocol, toNode: Node, protocol, request: seq[byte]):
Future[DiscResult[seq[byte]]] {.async.} =
## Send a discovery talkreq message.
##
## Returns the received talkresp message or an error.
let
msg = TalkReqMessage(protocol: protocol, request: request)
startTime = Moment.now()
resp = await d.waitResponse(toNode, msg)
rtt = Moment.now() - startTime
# trace "talk RTT:", rtt, node = toNode
toNode.registerRtt(rtt)
d.routingTable.setJustSeen(toNode, resp.isSome())
if resp.isSome():
if resp.get().kind == talkResp:
return ok(resp.get().talkResp.response)
else:
d.replaceNode(toNode)
dht_message_requests_outgoing.inc(labelValues = ["invalid_response"])
return err("Invalid response to talk request message")
else:
# remove on loss only if there is a replacement
d.replaceNode(toNode, NoreplyRemoveThreshold)
dht_message_requests_outgoing.inc(labelValues = ["no_response"])
return err("Talk response message not received in time")
proc lookupDistances*(target, dest: NodeId): seq[uint16] =
let td = logDistance(target, dest)
let tdAsInt = int(td)
result.add(td)
var i = 1
while result.len < LookupRequestLimit:
if tdAsInt + i < 256:
result.add(td + uint16(i))
if tdAsInt - i > 0:
result.add(td - uint16(i))
inc i
proc lookupWorker(d: Protocol, destNode: Node, target: NodeId, fast: bool):
Future[seq[Node]] {.async.} =
let r =
if fast:
await d.findNodeFast(destNode, target)
else:
# Instead of doing max `LookupRequestLimit` findNode requests, make use
# of the discv5.1 functionality to request nodes for multiple distances.
let dists = lookupDistances(target, destNode.id)
await d.findNode(destNode, dists)
if r.isOk:
result.add(r[])
# Attempt to add all nodes discovered
for n in result:
discard d.addNode(n)
proc lookup*(d: Protocol, target: NodeId, fast: bool = false): Future[seq[Node]] {.async.} =
## Perform a lookup for the given target, return the closest n nodes to the
## target. Maximum value for n is `BUCKET_SIZE`.
# `closestNodes` holds the k closest nodes to target found, sorted by distance
# Unvalidated nodes are used for requests as a form of validation.
var closestNodes = d.routingTable.neighbours(target, BUCKET_SIZE,
LookupSeenThreshold)
var asked, seen = initHashSet[NodeId]()
asked.incl(d.localNode.id) # No need to ask our own node
seen.incl(d.localNode.id) # No need to discover our own node
for node in closestNodes:
seen.incl(node.id)
var pendingQueries = newSeqOfCap[Future[seq[Node]]](Alpha)
while true:
var i = 0
# Doing `Alpha` amount of requests at once as long as closer non queried
# nodes are discovered.
while i < closestNodes.len and pendingQueries.len < Alpha:
let n = closestNodes[i]
if not asked.containsOrIncl(n.id):
pendingQueries.add(d.lookupWorker(n, target, fast))
inc i
trace "discv5 pending queries", total = pendingQueries.len
if pendingQueries.len == 0:
break
let query = await one(pendingQueries)
trace "Got discv5 lookup query response"
let index = pendingQueries.find(query)
if index != -1:
pendingQueries.del(index)
else:
error "Resulting query should have been in the pending queries"
let nodes = query.read
# TODO: Remove node on timed-out query?
for n in nodes:
if not seen.containsOrIncl(n.id):
# If it wasn't seen before, insert node while remaining sorted
closestNodes.insert(n, closestNodes.lowerBound(n,
proc(x: Node, n: Node): int =
cmp(distance(x.id, target), distance(n.id, target))
))
if closestNodes.len > BUCKET_SIZE:
closestNodes.del(closestNodes.high())
d.lastLookup = now(chronos.Moment)
trace "Closest nodes", nodes = closestNodes.len
return closestNodes
proc addProvider*(
d: Protocol,
cId: NodeId,
pr: SignedPeerRecord): Future[seq[Node]] {.async.} =
var res = await d.lookup(cId)
# TODO: lookup is specified as not returning local, even if that is the closest. Is this OK?
if res.len == 0:
res.add(d.localNode)
for toNode in res:
if toNode != d.localNode:
let reqId = RequestId.init(d.rng[])
d.sendRequest(toNode, AddProviderMessage(cId: cId, prov: pr), reqId)
else:
asyncSpawn d.addProviderLocal(cId, pr)
return res
proc sendGetProviders(d: Protocol, toNode: Node,
cId: NodeId): Future[DiscResult[ProvidersMessage]]
{.async.} =
let msg = GetProvidersMessage(cId: cId)
trace "sendGetProviders", toNode, msg
let
resp = await d.waitResponse(toNode, msg)
d.routingTable.setJustSeen(toNode, resp.isSome())
if resp.isSome():
if resp.get().kind == MessageKind.providers:
return ok(resp.get().provs)
else:
# TODO: do we need to do something when there is an invalid response?
d.replaceNode(toNode)
dht_message_requests_outgoing.inc(labelValues = ["invalid_response"])
return err("Invalid response to GetProviders message")
else:
# remove on loss only if there is a replacement
d.replaceNode(toNode, NoreplyRemoveThreshold)
dht_message_requests_outgoing.inc(labelValues = ["no_response"])
return err("GetProviders response message not received in time")
proc getProvidersLocal*(
d: Protocol,
cId: NodeId,
maxitems: int = 5,
): Future[seq[SignedPeerRecord]] {.async.} =
let provs = await d.providers.get(cId)
if provs.isErr:
trace "Unable to get local providers", cId, err = provs.error.msg
return provs.get
proc removeProvidersLocal*(
d: Protocol,
peerId: PeerId) {.async.} =
trace "Removing local provider", peerId
if(
let res = await d.providers.remove(peerId);
res.isErr):
trace "Error removing provider", err = res.error.msg
proc getProviders*(
d: Protocol,
cId: NodeId,
maxitems: int = 5,
timeout: Duration = 5000.milliseconds
): Future[DiscResult[seq[SignedPeerRecord]]] {.async.} =
# What providers do we know about?
var res = await d.getProvidersLocal(cId, maxitems)
trace "local providers:", prov = res.mapIt(it)
let nodesNearby = await d.lookup(cId)
trace "nearby:", nodesNearby
var providersFut: seq[Future[DiscResult[ProvidersMessage]]]
for n in nodesNearby:
if n != d.localNode:
providersFut.add(d.sendGetProviders(n, cId))
while providersFut.len > 0:
let providersMsg = await one(providersFut)
let index = providersFut.find(providersMsg)
if index != -1:
providersFut.del(index)
let providersMsg2 = await providersMsg
let providersMsgRes = providersMsg.read
if providersMsgRes.isOk:
let providers = providersMsgRes.get.provs
res = res.concat(providers).deduplicate
else:
error "Sending of GetProviders message failed", error = providersMsgRes.error
# TODO: should we consider this as an error result if all GetProviders
# requests fail??
trace "getProviders collected: ", res = res.mapIt(it.data)
return ok res
proc query*(d: Protocol, target: NodeId, k = BUCKET_SIZE): Future[seq[Node]]
{.async.} =
## Query k nodes for the given target, returns all nodes found, including the
## nodes queried.
##
## This will take k nodes from the routing table closest to target and
## query them for nodes closest to target. If there are less than k nodes in
## the routing table, nodes returned by the first queries will be used.
var queryBuffer = d.routingTable.neighbours(target, k, QuerySeenThreshold)
var asked, seen = initHashSet[NodeId]()
asked.incl(d.localNode.id) # No need to ask our own node
seen.incl(d.localNode.id) # No need to discover our own node
for node in queryBuffer:
seen.incl(node.id)
var pendingQueries = newSeqOfCap[Future[seq[Node]]](Alpha)
while true:
var i = 0
while i < min(queryBuffer.len, k) and pendingQueries.len < Alpha:
let n = queryBuffer[i]
if not asked.containsOrIncl(n.id):
pendingQueries.add(d.lookupWorker(n, target, false))
inc i
trace "discv5 pending queries", total = pendingQueries.len
if pendingQueries.len == 0:
break
let query = await one(pendingQueries)
trace "Got discv5 lookup query response"
let index = pendingQueries.find(query)
if index != -1:
pendingQueries.del(index)
else:
error "Resulting query should have been in the pending queries"
let nodes = query.read
# TODO: Remove node on timed-out query?
for n in nodes:
if not seen.containsOrIncl(n.id):
queryBuffer.add(n)
d.lastLookup = now(chronos.Moment)
return queryBuffer
proc queryRandom*(d: Protocol): Future[seq[Node]] =
## Perform a query for a random target, return all nodes discovered.
d.query(NodeId.random(d.rng[]))
proc queryRandom*(d: Protocol, enrField: (string, seq[byte])):
Future[seq[Node]] {.async.} =
## Perform a query for a random target, return all nodes discovered which
## contain enrField.
let nodes = await d.queryRandom()
var filtered: seq[Node]
for n in nodes:
if n.record.contains(enrField):
filtered.add(n)
return filtered
proc resolve*(d: Protocol, id: NodeId): Future[Option[Node]] {.async.} =
## Resolve a `Node` based on provided `NodeId`.
##
## This will first look in the own routing table. If the node is known, it
## will try to contact if for newer information. If node is not known or it
## does not reply, a lookup is done to see if it can find a (newer) record of
## the node on the network.
if id == d.localNode.id:
return some(d.localNode)
let node = d.getNode(id)
if node.isSome():
let request = await d.findNode(node.get(), @[0'u16])
# TODO: Handle failures better. E.g. stop on different failures than timeout
if request.isOk() and request[].len > 0:
trace "resolve (with local node found) is returning:", r = (request[][0])
return some(request[][0])
let discovered = await d.lookup(id)
for n in discovered:
if n.id == id:
if node.isSome() and node.get().record.seqNum >= n.record.seqNum:
trace "resolve (lookup) found node, but local one has greater or equal seqNum"
return node
else:
trace "resolve (lookup) found new node with equal or greater seqNum", n = n
return some(n)
return node
proc seedTable*(d: Protocol) =
## Seed the table with known nodes.
for record in d.bootstrapRecords:
if d.addNode(record):
debug "Added bootstrap node", uri = toURI(record)
else:
debug "Bootstrap node could not be added", uri = toURI(record)
# TODO:
# Persistent stored nodes could be added to seed from here
# See: https://github.com/status-im/nim-eth/issues/189
proc populateTable*(d: Protocol) {.async.} =
## Do a set of initial lookups to quickly populate the table.
# start with a self target query (neighbour nodes)
let selfQuery = await d.query(d.localNode.id)
trace "Discovered nodes in self target query", nodes = selfQuery.len
# `InitialLookups` random queries
for i in 0..<InitialLookups:
let randomQuery = await d.queryRandom()
trace "Discovered nodes in random target query", nodes = randomQuery.len
debug "Total nodes in routing table after populate",
total = d.routingTable.len()
proc revalidateNode*(d: Protocol, n: Node) {.async.} =
let pong = await d.ping(n)
if pong.isOk():
let res = pong.get()
if res.sprSeq > n.record.seqNum:
# Request new SPR
let nodes = await d.findNode(n, @[0'u16])
if nodes.isOk() and nodes[].len > 0:
discard d.addNode(nodes[][0])
# Get IP and port from pong message and add it to the ip votes
trace "pong rx", n, myip = res.ip, myport = res.port
let a = Address(ip: ValidIpAddress.init(res.ip), port: Port(res.port))
d.ipVote.insert(n.id, a)
proc revalidateLoop(d: Protocol) {.async.} =
## Loop which revalidates the nodes in the routing table by sending the ping
## message.
try:
while true:
let revalidateTimeout = RevalidateMin + d.rng[].rand(RevalidateMax - RevalidateMin)
await sleepAsync(milliseconds(revalidateTimeout))
let n = d.routingTable.nodeToRevalidate()
if not n.isNil:
traceAsyncErrors d.revalidateNode(n)
except CancelledError:
trace "revalidateLoop canceled"
trace "revalidator loop exited!"
proc refreshLoop(d: Protocol) {.async.} =
## Loop that refreshes the routing table by starting a random query in case
## no queries were done since `RefreshInterval` or more.
## It also refreshes the majority address voted for via pong responses.
try:
await d.populateTable()
while true:
let currentTime = now(chronos.Moment)
if currentTime > (d.lastLookup + RefreshInterval):
let randomQuery = await d.queryRandom()
trace "Discovered nodes in random target query", nodes = randomQuery.len
debug "Total nodes in discv5 routing table", total = d.routingTable.len()
await sleepAsync(RefreshInterval)
except CancelledError:
trace "refreshLoop canceled"
trace "refreshloop exited!"
proc ipMajorityLoop(d: Protocol) {.async.} =
#TODO this should be handled by libp2p, not the DHT
## When `enrAutoUpdate` is enabled, the IP:port combination returned
## by the majority will be used to update the local SPR.
## This should be safe as long as the routing table is not overwhelmed by
## malicious nodes trying to provide invalid addresses.
## Why is that?
## - Only one vote per NodeId is counted, and they are removed over time.
## - IP:port values are provided through the pong message. The local node
## initiates this by first sending a ping message. Unsolicited pong messages
## are ignored.
## - At interval pings are send to the least recently contacted node (tail of
## bucket) from a random bucket from the routing table.
## - Only messages that our node initiates (ping, findnode, talkreq) and that
## successfully get a response move a node to the head of the bucket.
## Additionally, findNode requests have typically a randomness to it, as they
## usually come from a query for random NodeId.
## - Currently, when a peer fails the respond, it gets replaced. It doesn't
## remain at the tail of the bucket.
## - There are IP limits on the buckets and the whole routing table.
try:
while true:
let majority = d.ipVote.majority()
if majority.isSome():
if d.localNode.address != majority:
let address = majority.get()
let previous = d.localNode.address
if d.enrAutoUpdate:
let res = d.localNode.update(d.privateKey,
ip = some(address.ip), udpPort = some(address.port))
if res.isErr:
warn "Failed updating SPR with newly discovered external address",
majority, previous, error = res.error
else:
dht_enr_auto_update.inc()
info "Updated SPR with newly discovered external address",
majority, previous, uri = toURI(d.localNode.record)
else:
warn "Discovered new external address but SPR auto update is off",
majority, previous
else:
debug "Discovered external address matches current address", majority,
current = d.localNode.address
await sleepAsync(IpMajorityInterval)
except CancelledError:
trace "ipMajorityLoop canceled"
trace "ipMajorityLoop exited!"
proc debugPrintLoop(d: Protocol) {.async.} =
## Loop which prints the neighborhood with stats
while true:
await sleepAsync(DebugPrintInterval)
for b in d.routingTable.buckets:
debug "bucket", depth = b.getDepth,
len = b.nodes.len, standby = b.replacementLen
for n in b.nodes:
debug "node", n, rttMin = n.stats.rttMin.int, rttAvg = n.stats.rttAvg.int,
reliability = n.seen.round(3)
# bandwidth estimates are based on limited information, so not logging it yet to avoid confusion
# trace "node", n, bwMaxMbps = (n.stats.bwMax / 1e6).round(3), bwAvgMbps = (n.stats.bwAvg / 1e6).round(3)
func init*(
T: type DiscoveryConfig,
tableIpLimit: uint,
bucketIpLimit: uint,
bitsPerHop: int): T =
DiscoveryConfig(
tableIpLimits: TableIpLimits(
tableIpLimit: tableIpLimit,
bucketIpLimit: bucketIpLimit),
bitsPerHop: bitsPerHop
)
proc newProtocol*(
privKey: PrivateKey,
enrIp: Option[ValidIpAddress],
enrTcpPort, enrUdpPort: Option[Port],
localEnrFields: openArray[(string, seq[byte])] = [],
bootstrapRecords: openArray[SignedPeerRecord] = [],
previousRecord = none[SignedPeerRecord](),
bindPort: Port,
bindIp = IPv4_any(),
enrAutoUpdate = false,
config = defaultDiscoveryConfig,
rng = newRng(),
providers = ProvidersManager.new(
SQLiteDatastore.new(Memory)
.expect("Should not fail!"))
): Protocol =
# TODO: Tried adding bindPort = udpPort as parameter but that gave
# "Error: internal error: environment misses: udpPort" in nim-beacon-chain.
# Anyhow, nim-beacon-chain would also require some changes to support port
# remapping through NAT and this API is also subject to change once we
# introduce support for ipv4 + ipv6 binding/listening.
# TODO: Implement SignedPeerRecord custom fields?
# let extraFields = mapIt(localEnrFields, toFieldPair(it[0], it[1]))
# TODO:
# - Defect as is now or return a result for spr errors?
# - In case incorrect key, allow for new spr based on new key (new node id)?
var record: SignedPeerRecord
if previousRecord.isSome():
record = previousRecord.get()
record.update(privKey, enrIp, enrTcpPort, enrUdpPort)
.expect("SignedPeerRecord within size limits and correct key")
else:
record = SignedPeerRecord.init(1, privKey, enrIp, enrTcpPort, enrUdpPort)
.expect("SignedPeerRecord within size limits")
info "SPR initialized", ip = enrIp, tcp = enrTcpPort, udp = enrUdpPort,
seqNum = record.seqNum, uri = toURI(record)
if enrIp.isNone():
if enrAutoUpdate:
notice "No external IP provided for the SPR, this node will not be " &
"discoverable until the SPR is updated with the discovered external IP address"
else:
warn "No external IP provided for the SPR, this node will not be discoverable"
let node = newNode(record).expect("Properly initialized record")
# TODO Consider whether this should be a Defect
doAssert rng != nil, "RNG initialization failed"
let
routingTable = RoutingTable.init(
node,
config.bitsPerHop,
config.tableIpLimits,
rng)
result = Protocol(
privateKey: privKey,
localNode: node,
bootstrapRecords: @bootstrapRecords,
ipVote: IpVote.init(),
enrAutoUpdate: enrAutoUpdate,
routingTable: routingTable,
rng: rng,
providers: providers)
result.transport = newTransport(result, privKey, node, bindPort, bindIp, rng)
proc newProtocol*(
privKey: PrivateKey,
bindPort: Port,
record: SignedPeerRecord,
bootstrapRecords: openArray[SignedPeerRecord] = [],
bindIp = IPv4_any(),
config = defaultDiscoveryConfig,
rng = newRng(),
providers = ProvidersManager.new(SQLiteDatastore.new(Memory)
.expect("Should not fail!"))
): Protocol =
## Initialize DHT protocol
##
info "Discovery SPR initialized", seqNum = record.seqNum, uri = toURI(record)
let
node = newNode(
bindIp,
bindPort,
privKey.getPublicKey.expect("Should get public key"),
record).expect("Properly initialized record")
# TODO Consider whether this should be a Defect
doAssert rng != nil, "RNG initialization failed"
result = Protocol(
privateKey: privKey,
localNode: node,
bootstrapRecords: @bootstrapRecords,
ipVote: IpVote.init(),
enrAutoUpdate: false, #TODO this should be removed from nim-libp2p-dht
routingTable: RoutingTable.init(
node, config.bitsPerHop, config.tableIpLimits, rng),
rng: rng,
providers: providers)
trace "newProtocol initiated."
result.transport = newTransport(result, privKey, node, bindPort, bindIp, rng)
proc open*(d: Protocol) {.raises: [Defect, CatchableError].} =
info "Starting discovery node", node = d.localNode
d.transport.open()
trace "Transport open."
d.seedTable()
trace "Routing table seeded."
proc start*(d: Protocol) {.async.} =
trace "Protocol start..."
d.refreshLoop = refreshLoop(d)
d.revalidateLoop = revalidateLoop(d)
d.ipMajorityLoop = ipMajorityLoop(d)
d.debugPrintLoop = debugPrintLoop(d)
await d.providers.start()
proc closeWait*(d: Protocol) {.async.} =
doAssert(not d.transport.closed)
debug "Closing discovery node", node = d.localNode
if not d.revalidateLoop.isNil:
await d.revalidateLoop.cancelAndWait()
if not d.refreshLoop.isNil:
await d.refreshLoop.cancelAndWait()
if not d.ipMajorityLoop.isNil:
await d.ipMajorityLoop.cancelAndWait()
await d.transport.closeWait()