95 lines
3.3 KiB
Nim
95 lines
3.3 KiB
Nim
import
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tables, sets, macros, base64,
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asyncdispatch2, nimcrypto/sysrand, chronicles, rlp, json_serialization,
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eth_p2p, eth_p2p/[rlpx, peer_pool],
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spec/[datatypes, crypto]
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type
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TopicMsgHandler = proc(msg: string): Future[void]
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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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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 connecetd", peer
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let gossipNet = peer.networkState
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for topic, _ in gossipNet.topicSubscribers:
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asyncCheck peer.subscribeFor(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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writeStackTrace()
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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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asyncCheck p.emit(topic, msgId, msg)
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let handler = peer.networkState.topicSubscribers.getOrDefault(topic)
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if handler != nil:
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await handler(msg)
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proc subscribeImpl(node: EthereumNode,
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topic: string,
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subscriber: TopicMsgHandler) =
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var gossipNet = node.protocolState(GossipSub)
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gossipNet.topicSubscribers[topic] = subscriber
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for peer in node.peers(GossipSub):
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discard peer.subscribeFor(topic)
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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.emit(topic, msgId, msg)
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proc makeMessageHandler[MsgType](userHandler: proc(msg: MsgType): Future[void]): TopicMsgHandler =
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result = proc (msg: string): Future[void] =
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userHandler Json.decode(msg, MsgType)
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macro subscribe*(node: EthereumNode, topic: string, handler: untyped): untyped =
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handler.addPragma ident"async"
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result = newCall(bindSym"subscribeImpl",
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node, topic, newCall(bindSym"makeMessageHandler", handler))
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proc broadcast*(node: EthereumNode, topic: string, msg: auto) {.async.} =
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await all(node.broadcastImpl(topic, Json.encode(msg)))
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