109 lines
3.8 KiB
Nim
109 lines
3.8 KiB
Nim
import
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tables, sets, macros, base64,
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chronos, nimcrypto/sysrand, chronicles, json_serialization,
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eth/[p2p, rlp], eth/p2p/[rlpx, peer_pool],
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spec/[datatypes, crypto],
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tracing/stacktraces
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type
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TopicMsgHandler = proc (msg: string)
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GossipSubPeer* = ref object
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sentMessages: HashSet[string]
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subscribedFor: HashSet[string]
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GossipSubNetwork* = ref object
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topicSubscribers: Table[string, TopicMsgHandler]
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handledMessages: HashSet[string]
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proc initProtocolState*(network: GossipSubNetwork, _: EthereumNode) =
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network.topicSubscribers = initTable[string, TopicMsgHandler]()
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network.handledMessages = initSet[string]()
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proc initProtocolState*(peer: GossipSubPeer, _: Peer) =
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peer.sentMessages = initSet[string]()
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peer.subscribedFor = initSet[string]()
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proc trySubscribing(peer: Peer, topic: string) {.gcsafe.}
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proc tryEmitting(peer: Peer, topic: string,
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msgId: string, msg: string): Future[void] {.gcsafe.}
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p2pProtocol GossipSub(version = 1,
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shortName = "gss",
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peerState = GossipSubPeer,
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networkState = GossipSubNetwork):
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# This is a very barebones emulation of the GossipSub protocol
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# available in LibP2P:
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onPeerConnected do (peer: Peer):
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info "GossipSub Peer connected", peer
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let gossipNet = peer.networkState
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for topic, _ in gossipNet.topicSubscribers:
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peer.trySubscribing(topic)
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onPeerDisconnected do (peer: Peer, reason: DisconnectionReason):
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info "GossipSub Peer disconnected", peer, reason
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proc subscribeFor(peer: Peer, topic: string) =
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peer.state.subscribedFor.incl topic
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proc emit(peer: Peer, topic: string, msgId: string, msg: string) =
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if msgId in peer.networkState.handledMessages:
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trace "Ignored previously handled message", msgId
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return
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peer.networkState.handledMessages.incl msgId
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for p in peer.network.peers(GossipSub):
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if msgId notin p.state.sentMessages and topic in p.state.subscribedFor:
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p.state.sentMessages.incl msgId
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asyncDiscard p.tryEmitting(topic, msgId, msg)
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{.gcsafe.}:
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let handler = peer.networkState.topicSubscribers.getOrDefault(topic)
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if handler != nil:
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handler(msg)
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proc broadcastIMPL(node: EthereumNode, topic: string, msg: string): seq[Future[void]] {.gcsafe.} =
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var randBytes: array[10, byte];
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if randomBytes(randBytes) != 10:
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warn "Failed to generate random message id"
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let msgId = base64.encode(randBytes)
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trace "Sending GossipSub message", msgId
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for peer in node.peers(GossipSub):
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if topic in peer.state(GossipSub).subscribedFor:
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result.add peer.tryEmitting(topic, msgId, msg)
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proc trySubscribing(peer: Peer, topic: string) =
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var fut = peer.subscribeFor(topic)
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fut.addCallback do (arg: pointer):
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if fut.failed:
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warn "Failed to subscribe to topic with GossipSub peer", topic, peer
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proc tryEmitting(peer: Peer, topic: string,
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msgId: string, msg: string): Future[void] =
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var fut = peer.emit(topic, msgId, msg)
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fut.addCallback do (arg: pointer):
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if fut.failed:
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warn "GossipSub message not delivered to Peer", peer
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return fut
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proc subscribe*[MsgType](node: EthereumNode,
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topic: string,
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userHandler: proc(msg: MsgType)) {.async.}=
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var gossipNet = node.protocolState(GossipSub)
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gossipNet.topicSubscribers[topic] = proc (msg: string) =
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userHandler Json.decode(msg, MsgType)
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for peer in node.peers(GossipSub):
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peer.trySubscribing(topic)
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proc broadcast*(node: EthereumNode, topic: string, msg: auto) {.async.} =
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# We are intentionally using `yield` here, so the broadcast call can
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# never fail. Please note that errors are logged through a callback
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# set in `tryEmitting`
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yield all(node.broadcastIMPL(topic, Json.encode(msg)))
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