## 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 std/[sequtils, strutils, tables, hashes] import chronos, chronicles, nimcrypto/sha2, metrics import rpc/[messages, message, protobuf], ../../peerid, ../../peerinfo, ../../stream/connection, ../../crypto/crypto, ../../protobuf/minprotobuf, ../../utility export peerid, connection logScope: topics = "pubsubpeer" when defined(libp2p_expensive_metrics): declareCounter(libp2p_pubsub_sent_messages, "number of messages sent", labels = ["id", "topic"]) declareCounter(libp2p_pubsub_received_messages, "number of messages received", labels = ["id", "topic"]) declareCounter(libp2p_pubsub_skipped_received_messages, "number of received skipped messages", labels = ["id"]) declareCounter(libp2p_pubsub_skipped_sent_messages, "number of sent skipped messages", labels = ["id"]) type PubSubObserver* = ref object onRecv*: proc(peer: PubSubPeer; msgs: var RPCMsg) {.gcsafe, raises: [Defect].} onSend*: proc(peer: PubSubPeer; msgs: var RPCMsg) {.gcsafe, raises: [Defect].} PubSubPeerEventKind* {.pure.} = enum Connected Disconnected PubsubPeerEvent* = object kind*: PubSubPeerEventKind GetConn* = proc(): Future[Connection] {.gcsafe.} OnEvent* = proc(peer: PubSubPeer, event: PubsubPeerEvent) {.gcsafe.} PubSubPeer* = ref object of RootObj getConn*: GetConn # callback to establish a new send connection onEvent*: OnEvent # Connectivity updates for peer codec*: string # the protocol that this peer joined from sendConn*: Connection # cached send connection connections*: seq[Connection] # connections to this peer peerId*: PeerID handler*: RPCHandler observers*: ref seq[PubSubObserver] # ref as in smart_ptr score*: float64 iWantBudget*: int iHaveBudget*: int outbound*: bool # if this is an outbound connection appScore*: float64 # application specific score behaviourPenalty*: float64 # the eventual penalty score RPCHandler* = proc(peer: PubSubPeer, msg: RPCMsg): Future[void] {.gcsafe.} func hash*(p: PubSubPeer): Hash = # int is either 32/64, so intptr basically, pubsubpeer is a ref cast[pointer](p).hash func shortLog*(p: PubSubPeer): string = if p.isNil: "PubSubPeer(nil)" else: shortLog(p.peerId) chronicles.formatIt(PubSubPeer): shortLog(it) proc connected*(p: PubSubPeer): bool = not p.sendConn.isNil and not (p.sendConn.closed or p.sendConn.atEof) proc hasObservers(p: PubSubPeer): bool = p.observers != nil and anyIt(p.observers[], it != nil) proc recvObservers(p: PubSubPeer, msg: var RPCMsg) = # trigger hooks if not(isNil(p.observers)) and p.observers[].len > 0: for obs in p.observers[]: if not(isNil(obs)): # TODO: should never be nil, but... obs.onRecv(p, msg) proc sendObservers(p: PubSubPeer, msg: var RPCMsg) = # trigger hooks if not(isNil(p.observers)) and p.observers[].len > 0: for obs in p.observers[]: if not(isNil(obs)): # TODO: should never be nil, but... obs.onSend(p, msg) proc handle*(p: PubSubPeer, conn: Connection) {.async.} = debug "starting pubsub read loop", conn, peer = p, closed = conn.closed try: try: while not conn.atEof: trace "waiting for data", conn, peer = p, closed = conn.closed let data = await conn.readLp(64 * 1024) trace "read data from peer", conn, peer = p, closed = conn.closed, data = data.shortLog var rmsg = decodeRpcMsg(data) if rmsg.isErr(): notice "failed to decode msg from peer", conn, peer = p, closed = conn.closed, err = rmsg.error() break trace "decoded msg from peer", conn, peer = p, closed = conn.closed, msg = rmsg.get().shortLog # trigger hooks p.recvObservers(rmsg.get()) when defined(libp2p_expensive_metrics): for m in rmsg.get().messages: for t in m.topicIDs: # metrics libp2p_pubsub_received_messages.inc(labelValues = [$p.peerId, t]) await p.handler(p, rmsg.get()) finally: await conn.close() 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 PubSubPeer.handle" except CatchableError as exc: trace "Exception occurred in PubSubPeer.handle", conn, peer = p, closed = conn.closed, exc = exc.msg finally: debug "exiting pubsub read loop", conn, peer = p, closed = conn.closed proc connectOnce(p: PubSubPeer): Future[void] {.async.} = try: let newConn = await p.getConn() if newConn.isNil: raise (ref CatchableError)(msg: "Cannot establish send connection") # When the send channel goes up, subscriptions need to be sent to the # remote peer - if we had multiple channels up and one goes down, all # stop working so we make an effort to only keep a single channel alive trace "Get new send connection", p, newConn p.sendConn = newConn if p.onEvent != nil: p.onEvent(p, PubsubPeerEvent(kind: PubSubPeerEventKind.Connected)) await handle(p, newConn) finally: if p.sendConn != nil: trace "Removing send connection", p, conn = p.sendConn await p.sendConn.close() p.sendConn = nil if p.onEvent != nil: p.onEvent(p, PubsubPeerEvent(kind: PubSubPeerEventKind.Disconnected)) proc connectImpl(p: PubSubPeer) {.async.} = try: # Keep trying to establish a connection while it's possible to do so - the # send connection might get disconnected due to a timeout or an unrelated # issue so we try to get a new on while true: await connectOnce(p) except CatchableError as exc: debug "Could not establish send connection", msg = exc.msg proc connect*(p: PubSubPeer) = asyncSpawn connectImpl(p) proc sendImpl(conn: Connection, encoded: seq[byte]) {.async.} = try: trace "sending encoded msgs to peer", conn, encoded = shortLog(encoded) await conn.writeLp(encoded) trace "sent pubsub message to remote", conn except CatchableError as exc: # Because we detach the send call from the currently executing task using # asyncSpawn, no exceptions may leak out of it trace "Unable to send to remote", conn, msg = exc.msg # Next time sendConn is used, it will be have its close flag set and thus # will be recycled await conn.close() # This will clean up the send connection proc send*(p: PubSubPeer, msg: RPCMsg, anonymize: bool) = doAssert(not isNil(p), "pubsubpeer nil!") let conn = p.sendConn if conn == nil or conn.closed(): trace "No send connection, skipping message", p, msg return trace "sending msg to peer", peer = p, rpcMsg = shortLog(msg) # When sending messages, we take care to re-encode them with the right # anonymization flag to ensure that we're not penalized for sending invalid # or malicious data on the wire - in particular, re-encoding protects against # some forms of valid but redundantly encoded protobufs with unknown or # duplicated fields let encoded = if p.hasObservers(): # trigger send hooks var mm = msg # hooks can modify the message p.sendObservers(mm) encodeRpcMsg(mm, anonymize) else: # If there are no send hooks, we redundantly re-encode the message to # protobuf for every peer - this could easily be improved! encodeRpcMsg(msg, anonymize) if encoded.len <= 0: debug "empty message, skipping", p, msg return # To limit the size of the closure, we only pass the encoded message and # connection to the spawned send task asyncSpawn sendImpl(conn, encoded) when defined(libp2p_expensive_metrics): for x in msg.messages: for t in x.topicIDs: # metrics libp2p_pubsub_sent_messages.inc(labelValues = [$p.peerId, t]) proc newPubSubPeer*(peerId: PeerID, getConn: GetConn, onEvent: OnEvent, codec: string): PubSubPeer = PubSubPeer( getConn: getConn, onEvent: onEvent, codec: codec, peerId: peerId, )