## 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. {.push raises: [Defect].} import std/[tables, options, sets, oids, sugar, math] import chronos, chronicles, metrics import stream/connection, transports/transport, upgrademngrs/[upgrade, muxedupgrade], multistream, multiaddress, protocols/protocol, protocols/secure/secure, peerinfo, protocols/identify, muxers/muxer, utils/semaphore, connmanager, peerid, peerstore, errors, dialer export connmanager, upgrade, dialer, peerstore logScope: topics = "libp2p switch" #TODO: General note - use a finite state machine to manage the different # steps of connections establishing and upgrading. This makes everything # more robust and less prone to ordering attacks - i.e. muxing can come if # and only if the channel has been secured (i.e. if a secure manager has been # previously provided) declareCounter(libp2p_failed_upgrades_incoming, "incoming connections failed upgrades") const ConcurrentUpgrades* = 4 type Switch* = ref object of Dial peerInfo*: PeerInfo connManager*: ConnManager transports*: seq[Transport] ms*: MultistreamSelect acceptFuts: seq[Future[void]] dialer*: Dial peerStore*: PeerStore proc addConnEventHandler*(s: Switch, handler: ConnEventHandler, kind: ConnEventKind) = s.connManager.addConnEventHandler(handler, kind) proc removeConnEventHandler*(s: Switch, handler: ConnEventHandler, kind: ConnEventKind) = s.connManager.removeConnEventHandler(handler, kind) proc addPeerEventHandler*(s: Switch, handler: PeerEventHandler, kind: PeerEventKind) = s.connManager.addPeerEventHandler(handler, kind) proc removePeerEventHandler*(s: Switch, handler: PeerEventHandler, kind: PeerEventKind) = s.connManager.removePeerEventHandler(handler, kind) proc isConnected*(s: Switch, peerId: PeerID): bool = ## returns true if the peer has one or more ## associated connections (sockets) ## peerId in s.connManager proc disconnect*(s: Switch, peerId: PeerID): Future[void] {.gcsafe.} = s.connManager.dropPeer(peerId) method connect*( s: Switch, peerId: PeerID, addrs: seq[MultiAddress]): Future[void] = s.dialer.connect(peerId, addrs) method dial*( s: Switch, peerId: PeerID, protos: seq[string]): Future[Connection] = s.dialer.dial(peerId, protos) proc dial*(s: Switch, peerId: PeerID, proto: string): Future[Connection] = dial(s, peerId, @[proto]) method dial*( s: Switch, peerId: PeerID, addrs: seq[MultiAddress], protos: seq[string]): Future[Connection] = s.dialer.dial(peerId, addrs, protos) proc dial*( s: Switch, peerId: PeerID, addrs: seq[MultiAddress], proto: string): Future[Connection] = dial(s, peerId, addrs, @[proto]) proc mount*[T: LPProtocol](s: Switch, proto: T, matcher: Matcher = nil) {.gcsafe, raises: [Defect, LPError].} = if isNil(proto.handler): raise newException(LPError, "Protocol has to define a handle method or proc") if proto.codec.len == 0: raise newException(LPError, "Protocol has to define a codec string") s.ms.addHandler(proto.codecs, proto, matcher) s.peerInfo.protocols.add(proto.codec) proc upgradeMonitor(conn: Connection, upgrades: AsyncSemaphore) {.async.} = ## monitor connection for upgrades ## try: # Since we don't control the flow of the # upgrade, this timeout guarantees that a # "hanged" remote doesn't hold the upgrade # forever await conn.onUpgrade.wait(30.seconds) # wait for connection to be upgraded trace "Connection upgrade succeeded" except CatchableError as exc: libp2p_failed_upgrades_incoming.inc() if not isNil(conn): await conn.close() trace "Exception awaiting connection upgrade", exc = exc.msg, conn finally: upgrades.release() # don't forget to release the slot! proc accept(s: Switch, transport: Transport) {.async.} = # noraises ## switch accept loop, ran for every transport ## let upgrades = newAsyncSemaphore(ConcurrentUpgrades) while transport.running: var conn: Connection try: debug "About to accept incoming connection" # remember to always release the slot when # the upgrade succeeds or fails, this is # currently done by the `upgradeMonitor` await upgrades.acquire() # first wait for an upgrade slot to become available conn = await s.connManager # next attempt to get an incoming connection .trackIncomingConn( () => transport.accept() ) if isNil(conn): # A nil connection means that we might have hit a # file-handle limit (or another non-fatal error), # we can get one on the next try, but we should # be careful to not end up in a thigh loop that # will starve the main event loop, thus we sleep # here before retrying. trace "Unable to get a connection, sleeping" await sleepAsync(100.millis) # TODO: should be configurable? upgrades.release() continue # set the direction of this bottom level transport # in order to be able to consume this information in gossipsub if required # gossipsub gives priority to connections we make conn.transportDir = Direction.In debug "Accepted an incoming connection", conn asyncSpawn upgradeMonitor(conn, upgrades) asyncSpawn transport.upgradeIncoming(conn) except CancelledError as exc: trace "releasing semaphore on cancellation" upgrades.release() # always release the slot except CatchableError as exc: debug "Exception in accept loop, exiting", exc = exc.msg upgrades.release() # always release the slot if not isNil(conn): await conn.close() return proc start*(s: Switch): Future[seq[Future[void]]] {.async, gcsafe.} = trace "starting switch for peer", peerInfo = s.peerInfo var startFuts: seq[Future[void]] for t in s.transports: # for each transport for i, a in s.peerInfo.addrs: if t.handles(a): # check if it handles the multiaddr var server = t.start(a) s.peerInfo.addrs[i] = t.ma # update peer's address s.acceptFuts.add(s.accept(t)) startFuts.add(server) proc peerIdentifiedHandler(peerInfo: PeerInfo, event: PeerEvent) {.async.} = s.peerStore.replace(peerInfo) s.connManager.addPeerEventHandler(peerIdentifiedHandler, PeerEventKind.Identified) debug "Started libp2p node", peer = s.peerInfo return startFuts # listen for incoming connections proc stop*(s: Switch) {.async.} = trace "Stopping switch" # close and cleanup all connections await s.connManager.close() for t in s.transports: try: await t.stop() except CancelledError as exc: raise exc except CatchableError as exc: warn "error cleaning up transports", msg = exc.msg try: await allFutures(s.acceptFuts) .wait(1.seconds) except CatchableError as exc: trace "Exception while stopping accept loops", exc = exc.msg # check that all futures were properly # stopped and otherwise cancel them for a in s.acceptFuts: if not a.finished: a.cancel() trace "Switch stopped" proc newSwitch*(peerInfo: PeerInfo, transports: seq[Transport], identity: Identify, muxers: Table[string, MuxerProvider], secureManagers: openarray[Secure] = [], connManager: ConnManager, ms: MultistreamSelect): Switch {.raises: [Defect, LPError].} = if secureManagers.len == 0: raise newException(LPError, "Provide at least one secure manager") let switch = Switch( peerInfo: peerInfo, ms: ms, transports: transports, connManager: connManager, peerStore: PeerStore.new(), dialer: Dialer.new(peerInfo, connManager, transports, ms)) switch.mount(identity) return switch proc isConnected*(s: Switch, peerInfo: PeerInfo): bool {.deprecated: "Use PeerID version".} = not isNil(peerInfo) and isConnected(s, peerInfo.peerId) proc disconnect*(s: Switch, peerInfo: PeerInfo): Future[void] {.deprecated: "Use PeerID version", gcsafe.} = disconnect(s, peerInfo.peerId) proc connect*(s: Switch, peerInfo: PeerInfo): Future[void] {.deprecated: "Use PeerID version".} = connect(s, peerInfo.peerId, peerInfo.addrs) proc dial*(s: Switch, peerInfo: PeerInfo, proto: string): Future[Connection] {.deprecated: "Use PeerID version".} = dial(s, peerInfo.peerId, peerInfo.addrs, proto)