## 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, metrics import pubsub, floodsub, pubsubpeer, mcache, timedcache, rpc/[messages, message], ../../crypto/crypto, ../protocol, ../../peerinfo, ../../connection, ../../peer, ../../errors, ../../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*: 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] # cancellation future for heartbeat interval heartbeatLock: AsyncLock # heartbeat lock to prevent two consecutive concurrent heartbeats 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... ## await g.handleConn(conn, proto) g.handler = handler g.codec = GossipSubCodec 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.getOrDefault(topic).len < GossipSubDLo: trace "replenishing fanout", peers = g.fanout.getOrDefault(topic).len if topic in g.gossipsub: for p in g.gossipsub.getOrDefault(topic): if not g.fanout[topic].containsOrIncl(p): if g.fanout.getOrDefault(topic).len == GossipSubD: break libp2p_gossipsub_peers_per_topic_fanout .set(g.fanout.getOrDefault(topic).len.int64, labelValues = [topic]) trace "fanout replenished with peers", peers = g.fanout.getOrDefault(topic).len proc rebalanceMesh(g: GossipSub, topic: string) {.async.} = try: 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.getOrDefault(topic).len < GossipSubDlo: trace "replenishing mesh", topic # replenish the mesh if we're below GossipSubDlo while g.mesh.getOrDefault(topic).len < GossipSubD: trace "gathering peers", peers = g.mesh.getOrDefault(topic).len await sleepAsync(1.millis) # don't starve the event loop var id: string if topic in g.fanout and g.fanout.getOrDefault(topic).len > 0: trace "getting peer from fanout", topic, peers = g.fanout.getOrDefault(topic).len id = sample(toSeq(g.fanout.getOrDefault(topic))) g.fanout[topic].excl(id) if id in g.fanout[topic]: continue # we already have this peer in the mesh, try again trace "got fanout peer", peer = id elif topic in g.gossipsub and g.gossipsub.getOrDefault(topic).len > 0: trace "getting peer from gossipsub", topic, peers = g.gossipsub.getOrDefault(topic).len id = sample(toSeq(g.gossipsub[topic])) g.gossipsub[topic].excl(id) if id in g.mesh[topic]: continue # we already have this peer in the mesh, try again 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.getOrDefault(topic).len > GossipSubDhi: trace "about to prune mesh", mesh = g.mesh.getOrDefault(topic).len while g.mesh.getOrDefault(topic).len > GossipSubD: trace "pruning peers", peers = g.mesh[topic].len let id = toSeq(g.mesh[topic])[rand(0.. val: dropping.add(topic) g.fanout.del(topic) for topic in dropping: g.lastFanoutPubSub.del(topic) libp2p_gossipsub_peers_per_topic_fanout .set(g.fanout.getOrDefault(topic).len.int64, labelValues = [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] = g.mesh.getOrDefault(topic) let fanout: HashSet[string] = g.fanout.getOrDefault(topic) let gossipPeers = mesh + fanout let mids = g.mcache.window(topic) if mids.len > 0: 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 g.gossipsub.getOrDefault(topic).len == 0: trace "no peers for topic, skipping", topicID = topic break let id = toSeq(g.gossipsub.getOrDefault(topic)).sample() g.gossipsub[topic].excl(id) if id notin gossipPeers: if id notin result: result[id] = ControlMessage() result[id].ihave.add(ihave) libp2p_gossipsub_peers_per_topic_gossipsub .set(g.gossipsub.getOrDefault(topic).len.int64, labelValues = [topic]) proc heartbeat(g: GossipSub) {.async.} = while true: try: await g.heartbeatLock.acquire() trace "running heartbeat" for t in toSeq(g.topics.keys): await g.rebalanceMesh(t) await g.dropFanoutPeers() let peers = g.getGossipPeers() var sent: seq[Future[void]] for peer in peers.keys: sent &= g.peers[peer].send(@[RPCMsg(control: some(peers[peer]))]) checkFutures(await allFinished(sent)) g.mcache.shift() # shift the cache except CatchableError as exc: trace "exception ocurred in gossipsub heartbeat", exc = exc.msg finally: g.heartbeatLock.release() await sleepAsync(1.seconds) 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) libp2p_gossipsub_peers_per_topic_gossipsub .set(g.gossipsub[t].len.int64, labelValues = [t]) # mostly for metrics await procCall PubSub(g).subscribeTopic(t, false, peer.id) for t in g.mesh.keys: g.mesh[t].excl(peer.id) libp2p_gossipsub_peers_per_topic_mesh .set(g.mesh[t].len.int64, labelValues = [t]) for t in g.fanout.keys: g.fanout[t].excl(peer.id) libp2p_gossipsub_peers_per_topic_fanout .set(g.fanout[t].len.int64, labelValues = [t]) method subscribeToPeer*(p: GossipSub, conn: Connection) {.async.} = await procCall PubSub(p).subscribeToPeer(conn) asyncCheck p.handleConn(conn, GossipSubCodec) method subscribeTopic*(g: GossipSub, topic: string, subscribe: bool, peerId: string) {.gcsafe, async.} = await 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 remote peer to the topic g.gossipsub[topic].incl(peerId) else: trace "removing subscription for topic", peer = peerId, name = topic # unsubscribe remote peer from the topic g.gossipsub[topic].excl(peerId) libp2p_gossipsub_peers_per_topic_gossipsub .set(g.gossipsub.getOrDefault(topic).len.int64, labelValues = [topic]) if topic in g.topics: await g.rebalanceMesh(topic) 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)) libp2p_gossipsub_peers_per_topic_mesh .set(g.mesh[graft.topicID].len.int64, labelValues = [graft.topicID]) libp2p_gossipsub_peers_per_topic_gossipsub .set(g.gossipsub[graft.topicID].len.int64, labelValues = [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) libp2p_gossipsub_peers_per_topic_mesh .set(g.mesh[prune.topicID].len.int64, labelValues = [prune.topicID]) proc handleIHave(g: GossipSub, peer: PubSubPeer, ihaves: seq[ControlIHave]): ControlIWant = for ihave in ihaves: trace "processing ihave message", peer = peer.id, topicID = 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 "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] 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 await g.rebalanceMesh(t) # gather peers for each topic 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, msgs = m.messages if id == peer.peerInfo.peerId: trace "not forwarding message to originator", peerId = id continue 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)]) 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 pair in topics: let topic = pair.topic if topic in g.mesh: let peers = g.mesh.getOrDefault(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.shortLog var peers: HashSet[string] if data.len > 0 and topic.len > 0: for _ in 0..<5: # try to get peers up to 5 times if peers.len > 0: break if topic in g.topics: # if we're subscribed to the topic attempt to build a mesh await g.rebalanceMesh(topic) peers = g.mesh.getOrDefault(topic) else: # send to fanout peers await g.replenishFanout(topic) if topic in g.fanout: peers = g.fanout.getOrDefault(topic) # set the fanout expiry time g.lastFanoutPubSub[topic] = Moment.fromNow(GossipSubFanoutTTL) # wait a second between tries await sleepAsync(1.seconds) 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])])) checkFutures(await allFinished(sent)) method start*(g: GossipSub) {.async.} = ## start pubsub ## start long running/repeating procedures # setup the heartbeat interval g.heartbeatCancel = 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() randomize() 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()