nim-libp2p/libp2p/protocols/pubsub/gossipsub.nim

452 lines
15 KiB
Nim

## 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.
import tables, sets, options, sequtils, random
import chronos, chronicles
import pubsub,
floodsub,
pubsubpeer,
mcache,
timedcache,
rpc/[messages, message],
../../crypto/crypto,
../protocol,
../../peerinfo,
../../connection,
../../peer,
../../errors
logScope:
topic = "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*: Table[string, HashSet[string]] # meshes - topic to peer
fanout*: Table[string, HashSet[string]] # fanout - topic to peer
gossipsub*: Table[string, HashSet[string]] # topic to peer map of all gossipsub peers
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
heartbeatCancel*: Future[void] # cancelation future for heartbeat interval
heartbeatLock: AsyncLock # hearbeat lock to prevent two concecutive concurent hearbeats
# TODO: This belong in chronos, temporary left here until chronos is updated
proc addInterval(every: Duration, cb: CallbackFunc,
udata: pointer = nil): Future[void] =
## Arrange the callback ``cb`` to be called on every ``Duration`` window
var retFuture = newFuture[void]("gossipsub.addInterval(Duration)")
proc interval(arg: pointer = nil) {.gcsafe.}
proc scheduleNext() =
if not retFuture.finished():
addTimer(Moment.fromNow(every), interval)
proc interval(arg: pointer = nil) {.gcsafe.} =
cb(udata)
scheduleNext()
scheduleNext()
return retFuture
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...
##
await g.handleConn(conn, proto)
g.handler = handler
g.codec = GossipSubCodec
method handleDisconnect(g: GossipSub, peer: PubSubPeer) {.async.} =
## handle peer disconnects
trace "peer disconnected", peer=peer.id
await procCall FloodSub(g).handleDisconnect(peer)
for t in g.gossipsub.keys:
g.gossipsub[t].excl(peer.id)
for t in g.mesh.keys:
g.mesh[t].excl(peer.id)
for t in g.fanout.keys:
g.fanout[t].excl(peer.id)
method subscribeTopic*(g: GossipSub,
topic: string,
subscribe: bool,
peerId: string) {.gcsafe.} =
procCall PubSub(g).subscribeTopic(topic, subscribe, peerId)
if topic notin g.gossipsub:
g.gossipsub[topic] = initHashSet[string]()
if subscribe:
trace "adding subscription for topic", peer = peerId, name = topic
# subscribe the peer to the topic
g.gossipsub[topic].incl(peerId)
else:
trace "removing subscription for topic", peer = peerId, name = topic
# unsubscribe the peer from the topic
g.gossipsub[topic].excl(peerId)
proc handleGraft(g: GossipSub,
peer: PubSubPeer,
grafts: seq[ControlGraft],
respControl: var ControlMessage) =
for graft in grafts:
trace "processing graft message", peer = peer.id,
topicID = graft.topicID
if graft.topicID in g.topics:
if g.mesh.len < GossipSubD:
g.mesh[graft.topicID].incl(peer.id)
else:
g.gossipsub[graft.topicID].incl(peer.id)
else:
respControl.prune.add(ControlPrune(topicID: graft.topicID))
proc handlePrune(g: GossipSub, peer: PubSubPeer, prunes: seq[ControlPrune]) =
for prune in prunes:
trace "processing prune message", peer = peer.id,
topicID = prune.topicID
if prune.topicID in g.mesh:
g.mesh[prune.topicID].excl(peer.id)
proc handleIHave(g: GossipSub, peer: PubSubPeer, ihaves: seq[
ControlIHave]): ControlIWant =
for ihave in ihaves:
trace "processing ihave message", peer = peer.id,
topicID = ihave.topicID
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 "processing iwant message", peer = peer.id,
messageID = mid
let msg = g.mcache.get(mid)
if msg.isSome:
result.add(msg.get())
method rpcHandler(g: GossipSub,
peer: PubSubPeer,
rpcMsgs: seq[RPCMsg]) {.async.} =
await procCall PubSub(g).rpcHandler(peer, rpcMsgs)
for m in rpcMsgs: # for all RPC messages
if m.messages.len > 0: # if there are any messages
var toSendPeers: HashSet[string] = initHashSet[string]()
for msg in m.messages: # for every message
trace "processing message with id", msg = msg.msgId
if msg.msgId in g.seen:
trace "message already processed, skipping", msg = msg.msgId
continue
g.seen.put(msg.msgId) # add the message to the seen cache
if g.verifySignature and not msg.verify(peer.peerInfo):
trace "dropping message due to failed signature verification"
continue
if not (await g.validate(msg)):
trace "dropping message due to failed validation"
continue
# this shouldn't happen
if g.peerInfo.peerId == msg.fromPeerId():
trace "skipping messages from self", msg = msg.msgId
continue
for t in msg.topicIDs: # for every topic in the message
if t in g.floodsub:
toSendPeers.incl(g.floodsub[t]) # get all floodsub peers for topic
if t in g.mesh:
toSendPeers.incl(g.mesh[t]) # get all mesh peers for topic
if t in g.topics: # if we're subscribed to the topic
for h in g.topics[t].handler:
trace "calling handler for message", msg = msg.msgId,
topicId = t,
localPeer = g.peerInfo.id,
fromPeer = msg.fromPeerId().pretty
await h(t, msg.data) # trigger user provided handler
# forward the message to all peers interested in it
for p in toSendPeers:
if p in g.peers:
let id = g.peers[p].peerInfo.peerId
trace "about to forward message to peer", peerId = id
if id != peer.peerInfo.peerId:
let msgs = m.messages.filterIt(
# don't forward to message originator
id != it.fromPeerId()
)
var sent: seq[Future[void]]
if msgs.len > 0:
trace "forwarding message to", peerId = id
sent.add(g.peers[p].send(@[RPCMsg(messages: msgs)]))
sent = await allFinished(sent)
checkFutures(sent)
var respControl: ControlMessage
if m.control.isSome:
var control: ControlMessage = m.control.get()
let iWant: ControlIWant = g.handleIHave(peer, control.ihave)
if iWant.messageIDs.len > 0:
respControl.iwant.add(iWant)
let messages: seq[Message] = g.handleIWant(peer, control.iwant)
g.handleGraft(peer, control.graft, respControl)
g.handlePrune(peer, control.prune)
if respControl.graft.len > 0 or respControl.prune.len > 0 or
respControl.ihave.len > 0 or respControl.iwant.len > 0:
await peer.send(@[RPCMsg(control: some(respControl), messages: messages)])
proc replenishFanout(g: GossipSub, topic: string) {.async.} =
## get fanout peers for a topic
trace "about to replenish fanout"
if topic notin g.fanout:
g.fanout[topic] = initHashSet[string]()
if g.fanout[topic].len < GossipSubDLo:
trace "replenishing fanout", peers = g.fanout[topic].len
if topic in g.gossipsub:
for p in g.gossipsub[topic]:
if not g.fanout[topic].containsOrIncl(p):
if g.fanout[topic].len == GossipSubD:
break
trace "fanout replenished with peers", peers = g.fanout[topic].len
proc rebalanceMesh(g: GossipSub, topic: string) {.async.} =
trace "about to rebalance mesh"
# create a mesh topic that we're subscribing to
if topic notin g.mesh:
g.mesh[topic] = initHashSet[string]()
if g.mesh[topic].len < GossipSubDlo:
trace "replenishing mesh"
# replenish the mesh if we're below GossipSubDlo
while g.mesh[topic].len < GossipSubD:
trace "gathering peers", peers = g.mesh[topic].len
var id: string
if topic in g.fanout and g.fanout[topic].len > 0:
id = g.fanout[topic].pop()
trace "got fanout peer", peer = id
elif topic in g.gossipsub and g.gossipsub[topic].len > 0:
id = g.gossipsub[topic].pop()
trace "got gossipsub peer", peer = id
else:
trace "no more peers"
break
g.mesh[topic].incl(id)
if id in g.peers:
let p = g.peers[id]
# send a graft message to the peer
await p.sendGraft(@[topic])
# prune peers if we've gone over
if g.mesh[topic].len > GossipSubDhi:
trace "pruning mesh"
while g.mesh[topic].len > GossipSubD:
trace "pruning peers", peers = g.mesh[topic].len
let id = toSeq(g.mesh[topic])[rand(0..<g.mesh[topic].len)]
g.mesh[topic].excl(id)
let p = g.peers[id]
# send a graft message to the peer
await p.sendPrune(@[topic])
trace "mesh balanced, got peers", peers = g.mesh[topic].len
proc dropFanoutPeers(g: GossipSub) {.async.} =
# drop peers that we haven't published to in
# GossipSubFanoutTTL seconds
var dropping = newSeq[string]()
for topic, val in g.lastFanoutPubSub:
if Moment.now > val:
dropping.add(topic)
g.fanout.del(topic)
for topic in dropping:
g.lastFanoutPubSub.del(topic)
proc getGossipPeers(g: GossipSub): Table[string, ControlMessage] {.gcsafe.} =
## gossip iHave messages to peers
let topics = toHashSet(toSeq(g.mesh.keys)) + toHashSet(toSeq(g.fanout.keys))
for topic in topics:
let mesh: HashSet[string] =
if topic in g.mesh:
g.mesh[topic]
else:
initHashSet[string]()
let fanout: HashSet[string] =
if topic in g.fanout:
g.fanout[topic]
else:
initHashSet[string]()
let gossipPeers = mesh + fanout
let mids = g.mcache.window(topic)
let ihave = ControlIHave(topicID: topic,
messageIDs: toSeq(mids))
if topic notin g.gossipsub:
trace "topic not in gossip array, skipping", topicID = topic
continue
while result.len < GossipSubD:
if not (g.gossipsub[topic].len > 0):
trace "no peers for topic, skipping", topicID = topic
break
let id = toSeq(g.gossipsub[topic]).sample()
g.gossipsub[topic].excl(id)
if id notin gossipPeers:
if id notin result:
result[id] = ControlMessage()
result[id].ihave.add(ihave)
proc heartbeat(g: GossipSub) {.async.} =
await g.heartbeatLock.acquire()
trace "running heartbeat"
await sleepAsync(GossipSubHeartbeatInitialDelay)
for t in g.mesh.keys:
await g.rebalanceMesh(t)
await g.dropFanoutPeers()
let peers = g.getGossipPeers()
for peer in peers.keys:
await g.peers[peer].send(@[RPCMsg(control: some(peers[peer]))])
g.mcache.shift() # shift the cache
g.heartbeatLock.release()
method subscribe*(g: GossipSub,
topic: string,
handler: TopicHandler) {.async.} =
await procCall PubSub(g).subscribe(topic, handler)
asyncCheck g.rebalanceMesh(topic)
method unsubscribe*(g: GossipSub,
topics: seq[TopicPair]) {.async.} =
await procCall PubSub(g).unsubscribe(topics)
for pair in topics:
let topic = pair.topic
if topic in g.mesh:
let peers = g.mesh[topic]
g.mesh.del(topic)
for id in peers:
let p = g.peers[id]
await p.sendPrune(@[topic])
method publish*(g: GossipSub,
topic: string,
data: seq[byte]) {.async.} =
await procCall PubSub(g).publish(topic, data)
trace "about to publish message on topic", name = topic,
data = data.toHex()
if data.len > 0 and topic.len > 0:
var peers: HashSet[string]
if topic in g.topics: # if we're subscribed to the topic attempt to build a mesh
await g.rebalanceMesh(topic)
peers = g.mesh[topic]
else: # send to fanout peers
await g.replenishFanout(topic)
if topic in g.fanout:
peers = g.fanout[topic]
# set the fanout expiery time
g.lastFanoutPubSub[topic] = Moment.fromNow(GossipSubFanoutTTL)
let msg = newMessage(g.peerInfo, data, topic, g.sign)
var sent: seq[Future[void]]
for p in peers:
if p == g.peerInfo.id:
continue
trace "publishing on topic", name = topic
g.mcache.put(msg)
sent.add(g.peers[p].send(@[RPCMsg(messages: @[msg])]))
sent = await allFinished(sent)
checkFutures(sent)
method start*(g: GossipSub) {.async.} =
## start pubsub
## start long running/repeating procedures
# setup the heartbeat interval
g.heartbeatCancel = addInterval(GossipSubHeartbeatInterval,
proc (arg: pointer = nil)
{.gcsafe, locks: 0.} =
asyncCheck g.heartbeat)
method stop*(g: GossipSub) {.async.} =
## stopt pubsub
## stop long running tasks
await g.heartbeatLock.acquire()
# stop heartbeat interval
if not g.heartbeatCancel.finished:
g.heartbeatCancel.complete()
g.heartbeatLock.release()
method initPubSub(g: GossipSub) =
procCall FloodSub(g).initPubSub()
g.mcache = newMCache(GossipSubHistoryGossip, GossipSubHistoryLength)
g.mesh = initTable[string, HashSet[string]]() # meshes - topic to peer
g.fanout = initTable[string, HashSet[string]]() # fanout - topic to peer
g.gossipsub = initTable[string, HashSet[string]]() # 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
g.heartbeatLock = newAsyncLock()