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## Nim-LibP2P
## Copyright (c) 2019 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.
# TODO: this module is temporary to allow
# for quick switchover fro 1.1 to 1.0.
# This should be removed once 1.1 is stable
# enough.
import std/[options, random, sequtils, sets, tables]
import chronos, chronicles, metrics
import ./pubsub,
./floodsub,
./pubsubpeer,
./peertable,
./mcache,
./timedcache,
./rpc/[messages, message],
../protocol,
../../stream/connection,
../../peerinfo,
../../peerid,
../../utility
logScope:
topics = "gossipsub"
const GossipSubCodec* = "/meshsub/1.0.0"
# overlay parameters
const GossipSubD* = 6
const GossipSubDlo* = 4
const GossipSubDhi* = 12
# gossip parameters
const GossipSubHistoryLength* = 5
const GossipSubHistoryGossip* = 3
# heartbeat interval
const GossipSubHeartbeatInitialDelay* = 100.millis
const GossipSubHeartbeatInterval* = 1.seconds
# fanout ttl
const GossipSubFanoutTTL* = 1.minutes
type
GossipSub* = ref object of FloodSub
mesh*: PeerTable # peers that we send messages to when we are subscribed to the topic
fanout*: PeerTable # peers that we send messages to when we're not subscribed to the topic
gossipsub*: PeerTable # peers that are subscribed to a topic
lastFanoutPubSub*: Table[string, Moment] # last publish time for fanout topics
gossip*: Table[string, seq[ControlIHave]] # pending gossip
control*: Table[string, ControlMessage] # pending control messages
mcache*: MCache # messages cache
heartbeatFut: Future[void] # cancellation future for heartbeat interval
heartbeatRunning: bool
heartbeatEvents*: seq[AsyncEvent]
parameters*: GossipSubParams
GossipSubParams* = object
# stubs
explicit: bool
pruneBackoff*: Duration
floodPublish*: bool
gossipFactor*: float64
dScore*: int
dOut*: int
dLazy*: int
gossipThreshold*: float64
publishThreshold*: float64
graylistThreshold*: float64
acceptPXThreshold*: float64
opportunisticGraftThreshold*: float64
decayInterval*: Duration
decayToZero*: float64
retainScore*: Duration
appSpecificWeight*: float64
ipColocationFactorWeight*: float64
ipColocationFactorThreshold*: float64
behaviourPenaltyWeight*: float64
behaviourPenaltyDecay*: float64
directPeers*: seq[PeerId]
proc init*(G: type[GossipSubParams]): G = discard
when defined(libp2p_expensive_metrics):
declareGauge(libp2p_gossipsub_peers_per_topic_mesh,
"gossipsub peers per topic in mesh",
labels = ["topic"])
declareGauge(libp2p_gossipsub_peers_per_topic_fanout,
"gossipsub peers per topic in fanout",
labels = ["topic"])
declareGauge(libp2p_gossipsub_peers_per_topic_gossipsub,
"gossipsub peers per topic in gossipsub",
labels = ["topic"])
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.codec = GossipSubCodec
proc replenishFanout(g: GossipSub, topic: string) =
## get fanout peers for a topic
logScope: topic
trace "about to replenish fanout"
if g.fanout.peers(topic) < GossipSubDLo:
trace "replenishing fanout", peers = g.fanout.peers(topic)
if topic in g.gossipsub:
for peer in g.gossipsub[topic]:
if g.fanout.addPeer(topic, peer):
if g.fanout.peers(topic) == GossipSubD:
break
when defined(libp2p_expensive_metrics):
libp2p_gossipsub_peers_per_topic_fanout
.set(g.fanout.peers(topic).int64, labelValues = [topic])
trace "fanout replenished with peers", peers = g.fanout.peers(topic)
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 _, peers in p.mesh.mpairs():
peers.excl(peer)
for _, peers in p.fanout.mpairs():
peers.excl(peer)
procCall FloodSub(p).onPubSubPeerEvent(peer, event)
proc rebalanceMesh(g: GossipSub, topic: string) {.async.} =
logScope:
topic
mesh = g.mesh.peers(topic)
gossipsub = g.gossipsub.peers(topic)
trace "rebalancing mesh"
# create a mesh topic that we're subscribing to
var
grafts, prunes: seq[PubSubPeer]
if g.mesh.peers(topic) < GossipSubDlo:
trace "replenishing mesh", peers = g.mesh.peers(topic)
# replenish the mesh if we're below Dlo
grafts = toSeq(
g.gossipsub.getOrDefault(topic, initHashSet[PubSubPeer]()) -
g.mesh.getOrDefault(topic, initHashSet[PubSubPeer]())
).filterIt(it.connected)
shuffle(grafts)
# Graft peers so we reach a count of D
grafts.setLen(min(grafts.len, GossipSubD - g.mesh.peers(topic)))
trace "grafting", grafts = grafts.len
for peer in grafts:
if g.mesh.addPeer(topic, peer):
g.fanout.removePeer(topic, peer)
if g.mesh.peers(topic) > GossipSubDhi:
# prune peers if we've gone over Dhi
prunes = toSeq(g.mesh[topic])
shuffle(prunes)
prunes.setLen(prunes.len - GossipSubD) # .. down to D peers
trace "pruning", prunes = prunes.len
for peer in prunes:
g.mesh.removePeer(topic, peer)
when defined(libp2p_expensive_metrics):
libp2p_gossipsub_peers_per_topic_gossipsub
.set(g.gossipsub.peers(topic).int64, labelValues = [topic])
libp2p_gossipsub_peers_per_topic_fanout
.set(g.fanout.peers(topic).int64, labelValues = [topic])
libp2p_gossipsub_peers_per_topic_mesh
.set(g.mesh.peers(topic).int64, labelValues = [topic])
trace "mesh balanced"
# Send changes to peers after table updates to avoid stale state
if grafts.len > 0:
let graft = RPCMsg(control: some(ControlMessage(graft: @[ControlGraft(topicID: topic)])))
g.broadcast(grafts, graft)
if prunes.len > 0:
let prune = RPCMsg(control: some(ControlMessage(prune: @[ControlPrune(topicID: topic)])))
g.broadcast(prunes, prune)
proc dropFanoutPeers(g: GossipSub) =
# drop peers that we haven't published to in
# GossipSubFanoutTTL seconds
let now = Moment.now()
for topic in toSeq(g.lastFanoutPubSub.keys):
let val = g.lastFanoutPubSub[topic]
if now > val:
g.fanout.del(topic)
g.lastFanoutPubSub.del(topic)
trace "dropping fanout topic", topic
when defined(libp2p_expensive_metrics):
libp2p_gossipsub_peers_per_topic_fanout
.set(g.fanout.peers(topic).int64, labelValues = [topic])
proc getGossipPeers(g: GossipSub): Table[PubSubPeer, ControlMessage] {.gcsafe.} =
## gossip iHave messages to peers
##
trace "getting gossip peers (iHave)"
let topics = toHashSet(toSeq(g.mesh.keys)) + toHashSet(toSeq(g.fanout.keys))
let controlMsg = ControlMessage()
for topic in topics:
var allPeers = toSeq(g.gossipsub.getOrDefault(topic))
shuffle(allPeers)
let mesh = g.mesh.getOrDefault(topic)
let fanout = g.fanout.getOrDefault(topic)
let gossipPeers = mesh + fanout
let mids = g.mcache.window(topic)
if not mids.len > 0:
continue
if topic notin g.gossipsub:
trace "topic not in gossip array, skipping", topic
continue
let ihave = ControlIHave(topicID: topic, messageIDs: toSeq(mids))
for peer in allPeers:
if result.len >= GossipSubD:
trace "got gossip peers", peers = result.len
break
if peer in gossipPeers:
continue
if peer notin result:
result[peer] = controlMsg
result[peer].ihave.add(ihave)
proc heartbeat(g: GossipSub) {.async.} =
while g.heartbeatRunning:
try:
trace "running heartbeat"
for t in toSeq(g.topics.keys):
await g.rebalanceMesh(t)
g.dropFanoutPeers()
# replenish known topics to the fanout
for t in toSeq(g.fanout.keys):
g.replenishFanout(t)
let peers = g.getGossipPeers()
for peer, control in peers:
g.peers.withValue(peer.peerId, pubsubPeer) do:
g.send(
pubsubPeer[],
RPCMsg(control: some(control)))
g.mcache.shift() # shift the cache
except CancelledError as exc:
raise exc
except CatchableError as exc:
warn "exception ocurred in gossipsub heartbeat", exc = exc.msg
for trigger in g.heartbeatEvents:
trace "firing heartbeat event", instance = cast[int](g)
trigger.fire()
await sleepAsync(GossipSubHeartbeatInterval)
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
for t in toSeq(g.gossipsub.keys):
g.gossipsub.removePeer(t, pubSubPeer)
when defined(libp2p_expensive_metrics):
libp2p_gossipsub_peers_per_topic_gossipsub
.set(g.gossipsub.peers(t).int64, labelValues = [t])
for t in toSeq(g.mesh.keys):
g.mesh.removePeer(t, pubSubPeer)
when defined(libp2p_expensive_metrics):
libp2p_gossipsub_peers_per_topic_mesh
.set(g.mesh.peers(t).int64, labelValues = [t])
for t in toSeq(g.fanout.keys):
g.fanout.removePeer(t, pubSubPeer)
when defined(libp2p_expensive_metrics):
libp2p_gossipsub_peers_per_topic_fanout
.set(g.fanout.peers(t).int64, labelValues = [t])
procCall FloodSub(g).unsubscribePeer(peer)
method subscribeTopic*(g: GossipSub,
topic: string,
subscribe: bool,
peer: PubSubPeer) {.gcsafe.} =
# Skip floodsub - we don't want it to add the peer to `g.floodsub`
procCall PubSub(g).subscribeTopic(topic, subscribe, peer)
logScope:
peer
topic
if subscribe:
trace "peer subscribed to topic"
# subscribe remote peer to the topic
discard g.gossipsub.addPeer(topic, peer)
else:
trace "peer unsubscribed from topic"
# unsubscribe remote peer from the topic
g.gossipsub.removePeer(topic, peer)
g.mesh.removePeer(topic, peer)
g.fanout.removePeer(topic, peer)
when defined(libp2p_expensive_metrics):
libp2p_gossipsub_peers_per_topic_mesh
.set(g.mesh.peers(topic).int64, labelValues = [topic])
libp2p_gossipsub_peers_per_topic_fanout
.set(g.fanout.peers(topic).int64, labelValues = [topic])
when defined(libp2p_expensive_metrics):
libp2p_gossipsub_peers_per_topic_gossipsub
.set(g.gossipsub.peers(topic).int64, labelValues = [topic])
trace "gossip peers", peers = g.gossipsub.peers(topic), topic
proc handleGraft(g: GossipSub,
peer: PubSubPeer,
grafts: seq[ControlGraft]): seq[ControlPrune] =
for graft in grafts:
let topic = graft.topicID
logScope:
peer
topic
trace "peer grafted topic"
# If they send us a graft before they send us a subscribe, what should
# we do? For now, we add them to mesh but don't add them to gossipsub.
if topic in g.topics:
if g.mesh.peers(topic) < GossipSubDHi:
# In the spec, there's no mention of DHi here, but implicitly, a
# peer will be removed from the mesh on next rebalance, so we don't want
# this peer to push someone else out
if g.mesh.addPeer(topic, peer):
g.fanout.removePeer(topic, peer)
else:
trace "peer already in mesh"
else:
result.add(ControlPrune(topicID: topic))
else:
debug "peer grafting topic we're not interested in"
result.add(ControlPrune(topicID: topic))
when defined(libp2p_expensive_metrics):
libp2p_gossipsub_peers_per_topic_mesh
.set(g.mesh.peers(topic).int64, labelValues = [topic])
libp2p_gossipsub_peers_per_topic_fanout
.set(g.fanout.peers(topic).int64, labelValues = [topic])
proc handlePrune(g: GossipSub, peer: PubSubPeer, prunes: seq[ControlPrune]) =
for prune in prunes:
trace "peer pruned topic", peer, topic = prune.topicID
g.mesh.removePeer(prune.topicID, peer)
when defined(libp2p_expensive_metrics):
libp2p_gossipsub_peers_per_topic_mesh
.set(g.mesh.peers(prune.topicID).int64, labelValues = [prune.topicID])
proc handleIHave(g: GossipSub,
peer: PubSubPeer,
ihaves: seq[ControlIHave]): ControlIWant =
for ihave in ihaves:
trace "peer sent ihave",
peer, topic = ihave.topicID, msgs = ihave.messageIDs
if ihave.topicID in g.mesh:
for m in ihave.messageIDs:
if m notin g.seen:
result.messageIDs.add(m)
proc handleIWant(g: GossipSub,
peer: PubSubPeer,
iwants: seq[ControlIWant]): seq[Message] =
for iwant in iwants:
for mid in iwant.messageIDs:
trace "peer sent iwant", peer, messageID = mid
let msg = g.mcache.get(mid)
if msg.isSome:
result.add(msg.get())
method rpcHandler*(g: GossipSub,
peer: PubSubPeer,
rpcMsg: RPCMsg) {.async.} =
await procCall PubSub(g).rpcHandler(peer, rpcMsg)
for msg in rpcMsg.messages: # for every message
let msgId = g.msgIdProvider(msg)
if g.seen.put(msgId):
trace "Dropping already-seen message", msgId, peer
continue
g.mcache.put(msgId, msg)
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, peer
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, peer
continue
# g.anonymize needs no evaluation when receiving messages
# as we have a "lax" policy and allow signed messages
if not (await g.validate(msg)):
trace "Dropping message due to failed validation", msgId, peer
continue
var toSendPeers = initHashSet[PubSubPeer]()
for t in msg.topicIDs: # for every topic in the message
g.floodsub.withValue(t, peers): toSendPeers.incl(peers[])
g.mesh.withValue(t, peers): toSendPeers.incl(peers[])
await handleData(g, t, msg.data)
# 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(toSeq(toSendPeers), RPCMsg(messages: @[msg]))
trace "forwared message to peers", peers = toSendPeers.len, msgId, peer
if rpcMsg.control.isSome:
let control = rpcMsg.control.get()
g.handlePrune(peer, control.prune)
var respControl: ControlMessage
respControl.iwant.add(g.handleIHave(peer, control.ihave))
respControl.prune.add(g.handleGraft(peer, control.graft))
let messages = g.handleIWant(peer, control.iwant)
if respControl.graft.len > 0 or respControl.prune.len > 0 or
respControl.ihave.len > 0 or messages.len > 0:
trace "sending control message", msg = shortLog(respControl), peer
g.send(
peer,
RPCMsg(control: some(respControl), messages: messages))
method subscribe*(g: GossipSub,
topic: string,
handler: TopicHandler) {.async.} =
await procCall PubSub(g).subscribe(topic, handler)
await g.rebalanceMesh(topic)
method unsubscribe*(g: GossipSub,
topics: seq[TopicPair]) {.async.} =
await procCall PubSub(g).unsubscribe(topics)
for (topic, handler) in topics:
# delete from mesh only if no handlers are left
if topic notin g.topics:
if topic in g.mesh:
let peers = g.mesh[topic]
g.mesh.del(topic)
let prune = RPCMsg(
control: some(ControlMessage(prune: @[ControlPrune(topicID: topic)])))
g.broadcast(toSeq(peers), prune)
method unsubscribeAll*(g: GossipSub, topic: string) {.async.} =
await procCall PubSub(g).unsubscribeAll(topic)
if topic in g.mesh:
let peers = g.mesh.getOrDefault(topic)
g.mesh.del(topic)
let prune = RPCMsg(control: some(ControlMessage(prune: @[ControlPrune(topicID: topic)])))
g.broadcast(toSeq(peers), prune)
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 topic in g.topics: # if we're subscribed use the mesh
peers = g.mesh.getOrDefault(topic)
else: # not subscribed, send to fanout peers
# try optimistically
peers = g.fanout.getOrDefault(topic)
if peers.len == 0:
# ok we had nothing.. let's try replenish inline
g.replenishFanout(topic)
peers = g.fanout.getOrDefault(topic)
# 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(GossipSubFanoutTTL)
if peers.len == 0:
debug "No peers for topic, skipping publish"
return 0
inc g.msgSeqno
let
msg =
if g.anonymize:
Message.init(none(PeerInfo), data, topic, none(uint64), false)
else:
Message.init(some(g.peerInfo), data, topic, some(g.msgSeqno), g.sign)
msgId = g.msgIdProvider(msg)
logScope: msgId
trace "Created new message", msg = shortLog(msg), peers = peers.len
if g.seen.put(msgId):
# custom msgid providers might cause this
trace "Dropping already-seen message"
return 0
g.mcache.put(msgId, msg)
g.broadcast(toSeq(peers), RPCMsg(messages: @[msg]))
when defined(libp2p_expensive_metrics):
if peers.len > 0:
libp2p_pubsub_messages_published.inc(labelValues = [topic])
trace "Published message to peers"
return peers.len
method start*(g: GossipSub) {.async.} =
trace "gossipsub start"
if not g.heartbeatFut.isNil:
warn "Starting gossipsub twice"
return
g.heartbeatRunning = true
g.heartbeatFut = g.heartbeat()
method stop*(g: GossipSub) {.async.} =
trace "gossipsub stop"
if g.heartbeatFut.isNil:
warn "Stopping gossipsub without starting it"
return
# stop heartbeat interval
g.heartbeatRunning = false
if not g.heartbeatFut.finished:
trace "awaiting last heartbeat"
await g.heartbeatFut
trace "heartbeat stopped"
g.heartbeatFut = nil
method initPubSub*(g: GossipSub) =
procCall FloodSub(g).initPubSub()
randomize()
g.mcache = MCache.init(GossipSubHistoryGossip, GossipSubHistoryLength)
g.mesh = initTable[string, HashSet[PubSubPeer]]() # meshes - topic to peer
g.fanout = initTable[string, HashSet[PubSubPeer]]() # fanout - topic to peer
g.gossipsub = initTable[string, HashSet[PubSubPeer]]()# topic to peer map of all gossipsub peers
g.lastFanoutPubSub = initTable[string, Moment]() # last publish time for fanout topics
g.gossip = initTable[string, seq[ControlIHave]]() # pending gossip
g.control = initTable[string, ControlMessage]() # pending control messages
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