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# Nim-LibP2P
# Copyright (c) 2023 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
# * MIT license ([LICENSE-MIT](LICENSE-MIT))
# at your option.
# This file may not be copied, modified, or distributed except according to
# those terms.
## Gossip based publishing
{.push raises: [].}
import std/[sets, sequtils]
import chronos, chronicles, metrics
import ./pubsub,
./floodsub,
./pubsubpeer,
./peertable,
./mcache,
./timedcache,
./rpc/[messages, message],
../protocol,
../../stream/connection,
../../peerinfo,
../../peerid,
../../utility,
../../switch
import stew/results
export results
import ./gossipsub/[types, scoring, behavior], ../../utils/heartbeat
export types, scoring, behavior, pubsub
logScope:
topics = "libp2p gossipsub"
declareCounter(libp2p_gossipsub_failed_publish, "number of failed publish")
declareCounter(libp2p_gossipsub_invalid_topic_subscription, "number of invalid topic subscriptions that happened")
declareCounter(libp2p_gossipsub_duplicate_during_validation, "number of duplicates received during message validation")
declareCounter(libp2p_gossipsub_duplicate, "number of duplicates received")
declareCounter(libp2p_gossipsub_received, "number of messages received (deduplicated)")
proc init*(_: type[GossipSubParams]): GossipSubParams =
GossipSubParams(
explicit: true,
pruneBackoff: 1.minutes,
unsubscribeBackoff: 5.seconds,
floodPublish: true,
gossipFactor: 0.25,
d: GossipSubD,
dLow: GossipSubDlo,
dHigh: GossipSubDhi,
dScore: GossipSubDlo,
dOut: GossipSubDlo - 1, # DLow - 1
dLazy: GossipSubD, # Like D
heartbeatInterval: GossipSubHeartbeatInterval,
historyLength: GossipSubHistoryLength,
historyGossip: GossipSubHistoryGossip,
fanoutTTL: GossipSubFanoutTTL,
seenTTL: 2.minutes,
gossipThreshold: -100,
publishThreshold: -1000,
graylistThreshold: -10000,
opportunisticGraftThreshold: 0,
decayInterval: 1.seconds,
decayToZero: 0.01,
retainScore: 2.minutes,
appSpecificWeight: 0.0,
ipColocationFactorWeight: 0.0,
ipColocationFactorThreshold: 1.0,
behaviourPenaltyWeight: -1.0,
behaviourPenaltyDecay: 0.999,
disconnectBadPeers: false,
enablePX: false
)
proc validateParameters*(parameters: GossipSubParams): Result[void, cstring] =
if (parameters.dOut >= parameters.dLow) or
(parameters.dOut > (parameters.d div 2)):
err("gossipsub: dOut parameter error, Number of outbound connections to keep in the mesh. Must be less than D_lo and at most D/2")
elif parameters.gossipThreshold >= 0:
err("gossipsub: gossipThreshold parameter error, Must be < 0")
elif parameters.unsubscribeBackoff.seconds <= 0:
err("gossipsub: unsubscribeBackoff parameter error, Must be > 0 seconds")
elif parameters.publishThreshold >= parameters.gossipThreshold:
err("gossipsub: publishThreshold parameter error, Must be < gossipThreshold")
elif parameters.graylistThreshold >= parameters.publishThreshold:
err("gossipsub: graylistThreshold parameter error, Must be < publishThreshold")
elif parameters.acceptPXThreshold < 0:
err("gossipsub: acceptPXThreshold parameter error, Must be >= 0")
elif parameters.opportunisticGraftThreshold < 0:
err("gossipsub: opportunisticGraftThreshold parameter error, Must be >= 0")
elif parameters.decayToZero > 0.5 or parameters.decayToZero <= 0.0:
err("gossipsub: decayToZero parameter error, Should be close to 0.0")
elif parameters.appSpecificWeight < 0:
err("gossipsub: appSpecificWeight parameter error, Must be positive")
elif parameters.ipColocationFactorWeight > 0:
err("gossipsub: ipColocationFactorWeight parameter error, Must be negative or 0")
elif parameters.ipColocationFactorThreshold < 1.0:
err("gossipsub: ipColocationFactorThreshold parameter error, Must be at least 1")
elif parameters.behaviourPenaltyWeight >= 0:
err("gossipsub: behaviourPenaltyWeight parameter error, Must be negative")
elif parameters.behaviourPenaltyDecay < 0 or parameters.behaviourPenaltyDecay >= 1:
err("gossipsub: behaviourPenaltyDecay parameter error, Must be between 0 and 1")
else:
ok()
proc validateParameters*(parameters: TopicParams): Result[void, cstring] =
if parameters.timeInMeshWeight <= 0.0 or parameters.timeInMeshWeight > 1.0:
err("gossipsub: timeInMeshWeight parameter error, Must be a small positive value")
elif parameters.timeInMeshCap <= 0.0:
err("gossipsub: timeInMeshCap parameter error, Should be a positive value")
elif parameters.firstMessageDeliveriesWeight <= 0.0:
err("gossipsub: firstMessageDeliveriesWeight parameter error, Should be a positive value")
elif parameters.meshMessageDeliveriesWeight >= 0.0:
err("gossipsub: meshMessageDeliveriesWeight parameter error, Should be a negative value")
elif parameters.meshMessageDeliveriesThreshold <= 0.0:
err("gossipsub: meshMessageDeliveriesThreshold parameter error, Should be a positive value")
elif parameters.meshMessageDeliveriesCap < parameters.meshMessageDeliveriesThreshold:
err("gossipsub: meshMessageDeliveriesCap parameter error, Should be >= meshMessageDeliveriesThreshold")
elif parameters.meshFailurePenaltyWeight >= 0.0:
err("gossipsub: meshFailurePenaltyWeight parameter error, Should be a negative value")
elif parameters.invalidMessageDeliveriesWeight >= 0.0:
err("gossipsub: invalidMessageDeliveriesWeight parameter error, Should be a negative value")
else:
ok()
method init*(g: GossipSub) =
proc handler(conn: Connection, proto: string) {.async.} =
## main protocol handler that gets triggered on every
## connection for a protocol string
## e.g. ``/floodsub/1.0.0``, etc...
##
try:
await g.handleConn(conn, proto)
except CancelledError:
# This is top-level procedure which will work as separate task, so it
# do not need to propogate CancelledError.
trace "Unexpected cancellation in gossipsub handler", conn
except CatchableError as exc:
trace "GossipSub handler leaks an error", exc = exc.msg, conn
g.handler = handler
g.codecs &= GossipSubCodec
g.codecs &= GossipSubCodec_10
method onNewPeer(g: GossipSub, peer: PubSubPeer) =
g.withPeerStats(peer.peerId) do (stats: var PeerStats):
# Make sure stats and peer information match, even when reloading peer stats
# from a previous connection
peer.score = stats.score
peer.appScore = stats.appScore
peer.behaviourPenalty = stats.behaviourPenalty
peer.iHaveBudget = IHavePeerBudget
peer.pingBudget = PingsPeerBudget
method onPubSubPeerEvent*(p: GossipSub, peer: PubSubPeer, event: PubSubPeerEvent) {.gcsafe.} =
case event.kind
of PubSubPeerEventKind.Connected:
discard
of PubSubPeerEventKind.Disconnected:
# If a send connection is lost, it's better to remove peer from the mesh -
# if it gets reestablished, the peer will be readded to the mesh, and if it
# doesn't, well.. then we hope the peer is going away!
for topic, peers in p.mesh.mpairs():
p.pruned(peer, topic)
peers.excl(peer)
for _, peers in p.fanout.mpairs():
peers.excl(peer)
procCall FloodSub(p).onPubSubPeerEvent(peer, event)
method unsubscribePeer*(g: GossipSub, peer: PeerId) =
## handle peer disconnects
##
trace "unsubscribing gossipsub peer", peer
let pubSubPeer = g.peers.getOrDefault(peer)
if pubSubPeer.isNil:
trace "no peer to unsubscribe", peer
return
# remove from peer IPs collection too
if pubSubPeer.address.isSome():
g.peersInIP.withValue(pubSubPeer.address.get(), s):
s[].excl(pubSubPeer.peerId)
if s[].len == 0:
g.peersInIP.del(pubSubPeer.address.get())
for t in toSeq(g.mesh.keys):
trace "pruning unsubscribing peer", pubSubPeer, score = pubSubPeer.score
g.pruned(pubSubPeer, t)
g.mesh.removePeer(t, pubSubPeer)
for t in toSeq(g.gossipsub.keys):
g.gossipsub.removePeer(t, pubSubPeer)
# also try to remove from explicit table here
g.explicit.removePeer(t, pubSubPeer)
for t in toSeq(g.fanout.keys):
g.fanout.removePeer(t, pubSubPeer)
g.peerStats.withValue(peer, stats):
for topic, info in stats[].topicInfos.mpairs:
info.firstMessageDeliveries = 0
procCall FloodSub(g).unsubscribePeer(peer)
proc handleSubscribe*(g: GossipSub,
peer: PubSubPeer,
topic: string,
subscribe: bool) =
logScope:
peer
topic
if subscribe:
# this is a workaround for a race condition
# that can happen if we disconnect the peer very early
# in the future we might use this as a test case
# and eventually remove this workaround
if peer.peerId notin g.peers:
trace "ignoring unknown peer"
return
if not(isNil(g.subscriptionValidator)) and not(g.subscriptionValidator(topic)):
# this is a violation, so warn should be in order
trace "ignoring invalid topic subscription", topic, peer
libp2p_gossipsub_invalid_topic_subscription.inc()
return
trace "peer subscribed to topic"
# subscribe remote peer to the topic
discard g.gossipsub.addPeer(topic, peer)
if peer.peerId in g.parameters.directPeers:
discard g.explicit.addPeer(topic, peer)
else:
trace "peer unsubscribed from topic"
if g.mesh.hasPeer(topic, peer):
#against spec
g.mesh.removePeer(topic, peer)
g.pruned(peer, topic)
# unsubscribe remote peer from the topic
g.gossipsub.removePeer(topic, peer)
g.fanout.removePeer(topic, peer)
if peer.peerId in g.parameters.directPeers:
g.explicit.removePeer(topic, peer)
trace "gossip peers", peers = g.gossipsub.peers(topic), topic
proc handleControl(g: GossipSub, peer: PubSubPeer, control: ControlMessage) =
g.handlePrune(peer, control.prune)
var respControl: ControlMessage
let iwant = g.handleIHave(peer, control.ihave)
if iwant.messageIds.len > 0:
respControl.iwant.add(iwant)
respControl.prune.add(g.handleGraft(peer, control.graft))
let messages = g.handleIWant(peer, control.iwant)
if
respControl.prune.len > 0 or
respControl.iwant.len > 0 or
messages.len > 0:
# iwant and prunes from here, also messages
for smsg in messages:
for topic in smsg.topicIds:
if g.knownTopics.contains(topic):
libp2p_pubsub_broadcast_messages.inc(labelValues = [topic])
else:
libp2p_pubsub_broadcast_messages.inc(labelValues = ["generic"])
libp2p_pubsub_broadcast_iwant.inc(respControl.iwant.len.int64)
for prune in respControl.prune:
if g.knownTopics.contains(prune.topicId):
libp2p_pubsub_broadcast_prune.inc(labelValues = [prune.topicId])
else:
libp2p_pubsub_broadcast_prune.inc(labelValues = ["generic"])
trace "sending control message", msg = shortLog(respControl), peer
g.send(
peer,
RPCMsg(control: some(respControl), messages: messages))
proc validateAndRelay(g: GossipSub,
msg: Message,
msgId, msgIdSalted: MessageId,
peer: PubSubPeer) {.async.} =
try:
let validation = await g.validate(msg)
var seenPeers: HashSet[PubSubPeer]
discard g.validationSeen.pop(msgIdSalted, seenPeers)
libp2p_gossipsub_duplicate_during_validation.inc(seenPeers.len.int64)
case validation
of ValidationResult.Reject:
debug "Dropping message after validation, reason: reject",
msgId = shortLog(msgId), peer
g.punishInvalidMessage(peer, msg.topicIds)
return
of ValidationResult.Ignore:
debug "Dropping message after validation, reason: ignore",
msgId = shortLog(msgId), peer
return
of ValidationResult.Accept:
discard
# store in cache only after validation
g.mcache.put(msgId, msg)
g.rewardDelivered(peer, msg.topicIds, true)
var toSendPeers = HashSet[PubSubPeer]()
for t in msg.topicIds: # for every topic in the message
if t notin g.topics:
continue
g.floodsub.withValue(t, peers): toSendPeers.incl(peers[])
g.mesh.withValue(t, peers): toSendPeers.incl(peers[])
# Don't send it to source peer, or peers that
# sent it during validation
toSendPeers.excl(peer)
toSendPeers.excl(seenPeers)
# In theory, if topics are the same in all messages, we could batch - we'd
# also have to be careful to only include validated messages
g.broadcast(toSendPeers, RPCMsg(messages: @[msg]))
trace "forwarded message to peers", peers = toSendPeers.len, msgId, peer
for topic in msg.topicIds:
if topic notin g.topics: continue
if g.knownTopics.contains(topic):
libp2p_pubsub_messages_rebroadcasted.inc(toSendPeers.len.int64, labelValues = [topic])
else:
libp2p_pubsub_messages_rebroadcasted.inc(toSendPeers.len.int64, labelValues = ["generic"])
await handleData(g, topic, msg.data)
except CatchableError as exc:
info "validateAndRelay failed", msg=exc.msg
method rpcHandler*(g: GossipSub,
peer: PubSubPeer,
rpcMsg: RPCMsg) {.async.} =
if rpcMsg.ping.len in 1..<64 and peer.pingBudget > 0:
g.send(peer, RPCMsg(pong: rpcMsg.ping))
peer.pingBudget.dec
for i in 0..<min(g.topicsHigh, rpcMsg.subscriptions.len):
template sub: untyped = rpcMsg.subscriptions[i]
g.handleSubscribe(peer, sub.topic, sub.subscribe)
# the above call applied limits to subs number
# in gossipsub we want to apply scoring as well
if rpcMsg.subscriptions.len > g.topicsHigh:
debug "received an rpc message with an oversized amount of subscriptions", peer,
size = rpcMsg.subscriptions.len,
limit = g.topicsHigh
peer.behaviourPenalty += 0.1
for i in 0..<rpcMsg.messages.len(): # for every message
template msg: untyped = rpcMsg.messages[i]
let msgIdResult = g.msgIdProvider(msg)
if msgIdResult.isErr:
debug "Dropping message due to failed message id generation",
error = msgIdResult.error
# TODO: descore peers due to error during message validation (malicious?)
continue
let
msgId = msgIdResult.get
msgIdSalted = msgId & g.seenSalt
# addSeen adds salt to msgId to avoid
# remote attacking the hash function
if g.addSeen(msgId):
trace "Dropping already-seen message", msgId = shortLog(msgId), peer
var alreadyReceived = false
g.validationSeen.withValue(msgIdSalted, seen):
if seen[].containsOrIncl(peer):
# peer sent us this message twice
alreadyReceived = true
if not alreadyReceived:
let delay = Moment.now() - g.firstSeen(msgId)
g.rewardDelivered(peer, msg.topicIds, false, delay)
libp2p_gossipsub_duplicate.inc()
# onto the next message
continue
libp2p_gossipsub_received.inc()
# avoid processing messages we are not interested in
if msg.topicIds.allIt(it notin g.topics):
debug "Dropping message of topic without subscription", msgId = shortLog(msgId), peer
continue
if (msg.signature.len > 0 or g.verifySignature) and not msg.verify():
# always validate if signature is present or required
debug "Dropping message due to failed signature verification",
msgId = shortLog(msgId), peer
g.punishInvalidMessage(peer, msg.topicIds)
continue
if msg.seqno.len > 0 and msg.seqno.len != 8:
# if we have seqno should be 8 bytes long
debug "Dropping message due to invalid seqno length",
msgId = shortLog(msgId), peer
g.punishInvalidMessage(peer, msg.topicIds)
continue
# g.anonymize needs no evaluation when receiving messages
# as we have a "lax" policy and allow signed messages
# Be careful not to fill the validationSeen table
# (eg, pop everything you put in it)
g.validationSeen[msgIdSalted] = initHashSet[PubSubPeer]()
asyncSpawn g.validateAndRelay(msg, msgId, msgIdSalted, peer)
if rpcMsg.control.isSome():
g.handleControl(peer, rpcMsg.control.unsafeGet())
# Now, check subscription to update the meshes if required
for i in 0..<min(g.topicsHigh, rpcMsg.subscriptions.len):
let topic = rpcMsg.subscriptions[i].topic
if topic in g.topics and g.mesh.peers(topic) < g.parameters.dLow:
# rebalance but don't update metrics here, we do that only in the heartbeat
g.rebalanceMesh(topic, metrics = nil)
g.updateMetrics(rpcMsg)
method onTopicSubscription*(g: GossipSub, topic: string, subscribed: bool) =
if subscribed:
procCall PubSub(g).onTopicSubscription(topic, subscribed)
# if we have a fanout on this topic break it
if topic in g.fanout:
g.fanout.del(topic)
# rebalance but don't update metrics here, we do that only in the heartbeat
g.rebalanceMesh(topic, metrics = nil)
else:
let mpeers = g.mesh.getOrDefault(topic)
# Remove peers from the mesh since we're no longer both interested
# in the topic
let msg = RPCMsg(control: some(ControlMessage(
prune: @[ControlPrune(
topicID: topic,
peers: g.peerExchangeList(topic),
backoff: g.parameters.unsubscribeBackoff.seconds.uint64)])))
g.broadcast(mpeers, msg)
for peer in mpeers:
g.pruned(peer, topic, backoff = some(g.parameters.unsubscribeBackoff))
g.mesh.del(topic)
# Send unsubscribe (in reverse order to sub/graft)
procCall PubSub(g).onTopicSubscription(topic, subscribed)
method publish*(g: GossipSub,
topic: string,
data: seq[byte]): Future[int] {.async.} =
# base returns always 0
discard await procCall PubSub(g).publish(topic, data)
logScope:
topic
trace "Publishing message on topic", data = data.shortLog
if topic.len <= 0: # data could be 0/empty
debug "Empty topic, skipping publish"
return 0
var peers: HashSet[PubSubPeer]
if g.parameters.floodPublish:
# With flood publishing enabled, the mesh is used when propagating messages from other peers,
# but a peer's own messages will always be published to all known peers in the topic.
for peer in g.gossipsub.getOrDefault(topic):
if peer.score >= g.parameters.publishThreshold:
trace "publish: including flood/high score peer", peer
peers.incl(peer)
# add always direct peers
peers.incl(g.explicit.getOrDefault(topic))
if topic in g.topics: # if we're subscribed use the mesh
peers.incl(g.mesh.getOrDefault(topic))
if peers.len < g.parameters.dLow and g.parameters.floodPublish == false:
# not subscribed or bad mesh, send to fanout peers
# disable for floodPublish, since we already sent to every good peer
#
var fanoutPeers = g.fanout.getOrDefault(topic).toSeq()
if fanoutPeers.len == 0:
g.replenishFanout(topic)
fanoutPeers = g.fanout.getOrDefault(topic).toSeq()
g.rng.shuffle(fanoutPeers)
if fanoutPeers.len + peers.len > g.parameters.d:
fanoutPeers.setLen(g.parameters.d - peers.len)
for fanPeer in fanoutPeers:
peers.incl(fanPeer)
if peers.len > g.parameters.d: break
# even if we couldn't publish,
# we still attempted to publish
# on the topic, so it makes sense
# to update the last topic publish
# time
g.lastFanoutPubSub[topic] = Moment.fromNow(g.parameters.fanoutTTL)
if peers.len == 0:
let topicPeers = g.gossipsub.getOrDefault(topic).toSeq()
debug "No peers for topic, skipping publish", peersOnTopic = topicPeers.len,
connectedPeers = topicPeers.filterIt(it.connected).len,
topic
# skipping topic as our metrics finds that heavy
libp2p_gossipsub_failed_publish.inc()
return 0
let
msg =
if g.anonymize:
Message.init(none(PeerInfo), data, topic, none(uint64), false)
else:
inc g.msgSeqno
Message.init(some(g.peerInfo), data, topic, some(g.msgSeqno), g.sign)
msgId = g.msgIdProvider(msg).valueOr:
trace "Error generating message id, skipping publish",
error = error
libp2p_gossipsub_failed_publish.inc()
return 0
logScope: msgId = shortLog(msgId)
trace "Created new message", msg = shortLog(msg), peers = peers.len
if g.addSeen(msgId):
# custom msgid providers might cause this
trace "Dropping already-seen message"
return 0
g.mcache.put(msgId, msg)
g.broadcast(peers, RPCMsg(messages: @[msg]))
if g.knownTopics.contains(topic):
libp2p_pubsub_messages_published.inc(peers.len.int64, labelValues = [topic])
else:
libp2p_pubsub_messages_published.inc(peers.len.int64, labelValues = ["generic"])
trace "Published message to peers", peers=peers.len
return peers.len
proc maintainDirectPeer(g: GossipSub, id: PeerId, addrs: seq[MultiAddress]) {.async.} =
let peer = g.peers.getOrDefault(id)
if isNil(peer):
trace "Attempting to dial a direct peer", peer = id
try:
await g.switch.connect(id, addrs)
# populate the peer after it's connected
discard g.getOrCreatePeer(id, g.codecs)
except CancelledError as exc:
trace "Direct peer dial canceled"
raise exc
except CatchableError as exc:
debug "Direct peer error dialing", msg = exc.msg
proc addDirectPeer*(g: GossipSub, id: PeerId, addrs: seq[MultiAddress]) {.async.} =
g.parameters.directPeers[id] = addrs
await g.maintainDirectPeer(id, addrs)
proc maintainDirectPeers(g: GossipSub) {.async.} =
heartbeat "GossipSub DirectPeers", 1.minutes:
for id, addrs in g.parameters.directPeers:
await g.addDirectPeer(id, addrs)
method start*(g: GossipSub) {.async.} =
trace "gossipsub start"
if not g.heartbeatFut.isNil:
warn "Starting gossipsub twice"
return
g.heartbeatFut = g.heartbeat()
g.scoringHeartbeatFut = g.scoringHeartbeat()
g.directPeersLoop = g.maintainDirectPeers()
g.started = true
method stop*(g: GossipSub) {.async.} =
trace "gossipsub stop"
g.started = false
if g.heartbeatFut.isNil:
warn "Stopping gossipsub without starting it"
return
# stop heartbeat interval
g.directPeersLoop.cancel()
g.scoringHeartbeatFut.cancel()
g.heartbeatFut.cancel()
g.heartbeatFut = nil
method initPubSub*(g: GossipSub)
{.raises: [InitializationError].} =
procCall FloodSub(g).initPubSub()
if not g.parameters.explicit:
g.parameters = GossipSubParams.init()
let validationRes = g.parameters.validateParameters()
if validationRes.isErr:
raise newException(InitializationError, $validationRes.error)
# init the floodsub stuff here, we customize timedcache in gossip!
g.seen = TimedCache[MessageId].init(g.parameters.seenTTL)
# init gossip stuff
g.mcache = MCache.init(g.parameters.historyGossip, g.parameters.historyLength)
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