400 lines
12 KiB
Nim
400 lines
12 KiB
Nim
# Nim-LibP2P
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# Copyright (c) 2022 Status Research & Development GmbH
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# Licensed under either of
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# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
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# * MIT license ([LICENSE-MIT](LICENSE-MIT))
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# at your option.
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# This file may not be copied, modified, or distributed except according to
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# those terms.
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## The switch is the core of libp2p, which brings together the
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## transports, the connection manager, the upgrader and other
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## parts to allow programs to use libp2p
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when (NimMajor, NimMinor) < (1, 4):
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{.push raises: [Defect].}
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else:
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{.push raises: [].}
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import std/[tables,
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options,
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sequtils,
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sets,
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oids,
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sugar,
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math]
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import chronos,
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chronicles,
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metrics
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import stream/connection,
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transports/transport,
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upgrademngrs/[upgrade, muxedupgrade],
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multistream,
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multiaddress,
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protocols/protocol,
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protocols/secure/secure,
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peerinfo,
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protocols/identify,
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muxers/muxer,
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utils/semaphore,
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connmanager,
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nameresolving/nameresolver,
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peerid,
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peerstore,
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errors,
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utility,
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dialer
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export connmanager, upgrade, dialer, peerstore
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logScope:
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topics = "libp2p switch"
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#TODO: General note - use a finite state machine to manage the different
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# steps of connections establishing and upgrading. This makes everything
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# more robust and less prone to ordering attacks - i.e. muxing can come if
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# and only if the channel has been secured (i.e. if a secure manager has been
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# previously provided)
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declareCounter(libp2p_failed_upgrades_incoming, "incoming connections failed upgrades")
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const
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ConcurrentUpgrades* = 4
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type
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Switch* {.public.} = ref object of Dial
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peerInfo*: PeerInfo
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connManager*: ConnManager
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transports*: seq[Transport]
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ms*: MultistreamSelect
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acceptFuts: seq[Future[void]]
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dialer*: Dial
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peerStore*: PeerStore
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nameResolver*: NameResolver
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started: bool
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services*: seq[Service]
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Service* = ref object of RootObj
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inUse: bool
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method setup*(self: Service, switch: Switch): Future[bool] {.base, async, gcsafe.} =
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if self.inUse:
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warn "service setup has already been called"
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return false
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self.inUse = true
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return true
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method run*(self: Service, switch: Switch) {.base, async, gcsafe.} =
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doAssert(false, "Not implemented!")
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method stop*(self: Service, switch: Switch): Future[bool] {.base, async, gcsafe.} =
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if not self.inUse:
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warn "service is already stopped"
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return false
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self.inUse = false
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return true
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proc addConnEventHandler*(s: Switch,
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handler: ConnEventHandler,
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kind: ConnEventKind) {.public.} =
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## Adds a ConnEventHandler, which will be triggered when
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## a connection to a peer is created or dropped.
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## There may be multiple connections per peer.
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##
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## The handler should not raise.
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s.connManager.addConnEventHandler(handler, kind)
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proc removeConnEventHandler*(s: Switch,
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handler: ConnEventHandler,
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kind: ConnEventKind) {.public.} =
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s.connManager.removeConnEventHandler(handler, kind)
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proc addPeerEventHandler*(s: Switch,
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handler: PeerEventHandler,
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kind: PeerEventKind) {.public.} =
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## Adds a PeerEventHandler, which will be triggered when
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## a peer connects or disconnects from us.
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##
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## The handler should not raise.
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s.connManager.addPeerEventHandler(handler, kind)
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proc removePeerEventHandler*(s: Switch,
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handler: PeerEventHandler,
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kind: PeerEventKind) {.public.} =
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s.connManager.removePeerEventHandler(handler, kind)
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method addTransport*(s: Switch, t: Transport) =
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s.transports &= t
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s.dialer.addTransport(t)
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proc connectedPeers*(s: Switch, dir: Direction): seq[PeerId] =
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s.connManager.connectedPeers(dir)
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proc isConnected*(s: Switch, peerId: PeerId): bool {.public.} =
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## returns true if the peer has one or more
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## associated connections
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##
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peerId in s.connManager
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proc disconnect*(s: Switch, peerId: PeerId): Future[void] {.gcsafe, public.} =
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## Disconnect from a peer, waiting for the connection(s) to be dropped
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s.connManager.dropPeer(peerId)
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method connect*(
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s: Switch,
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peerId: PeerId,
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addrs: seq[MultiAddress],
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forceDial = false): Future[void] {.public.} =
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## Connects to a peer without opening a stream to it
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s.dialer.connect(peerId, addrs, forceDial)
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method connect*(
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s: Switch,
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address: MultiAddress,
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allowUnknownPeerId = false): Future[PeerId] =
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## Connects to a peer and retrieve its PeerId
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##
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## If the P2P part is missing from the MA and `allowUnknownPeerId` is set
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## to true, this will discover the PeerId while connecting. This exposes
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## you to MiTM attacks, so it shouldn't be used without care!
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s.dialer.connect(address, allowUnknownPeerId)
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method dial*(
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s: Switch,
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peerId: PeerId,
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protos: seq[string]): Future[Connection] {.public.} =
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## Open a stream to a connected peer with the specified `protos`
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s.dialer.dial(peerId, protos)
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proc dial*(s: Switch,
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peerId: PeerId,
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proto: string): Future[Connection] {.public.} =
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## Open a stream to a connected peer with the specified `proto`
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dial(s, peerId, @[proto])
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method dial*(
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s: Switch,
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peerId: PeerId,
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addrs: seq[MultiAddress],
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protos: seq[string],
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forceDial = false): Future[Connection] {.public.} =
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## Connected to a peer and open a stream
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## with the specified `protos`
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s.dialer.dial(peerId, addrs, protos, forceDial)
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proc dial*(
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s: Switch,
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peerId: PeerId,
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addrs: seq[MultiAddress],
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proto: string): Future[Connection] {.public.} =
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## Connected to a peer and open a stream
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## with the specified `proto`
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dial(s, peerId, addrs, @[proto])
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proc mount*[T: LPProtocol](s: Switch, proto: T, matcher: Matcher = nil)
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{.gcsafe, raises: [Defect, LPError], public.} =
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## mount a protocol to the switch
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if isNil(proto.handler):
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raise newException(LPError,
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"Protocol has to define a handle method or proc")
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if proto.codec.len == 0:
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raise newException(LPError,
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"Protocol has to define a codec string")
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if s.started and not proto.started:
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raise newException(LPError, "Protocol not started")
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s.ms.addHandler(proto.codecs, proto, matcher)
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s.peerInfo.protocols.add(proto.codec)
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proc upgradeMonitor(conn: Connection, upgrades: AsyncSemaphore) {.async.} =
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## monitor connection for upgrades
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##
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try:
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# Since we don't control the flow of the
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# upgrade, this timeout guarantees that a
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# "hanged" remote doesn't hold the upgrade
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# forever
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await conn.onUpgrade.wait(30.seconds) # wait for connection to be upgraded
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trace "Connection upgrade succeeded"
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except CatchableError as exc:
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libp2p_failed_upgrades_incoming.inc()
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if not isNil(conn):
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await conn.close()
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trace "Exception awaiting connection upgrade", exc = exc.msg, conn
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finally:
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upgrades.release() # don't forget to release the slot!
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proc accept(s: Switch, transport: Transport) {.async.} = # noraises
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## switch accept loop, ran for every transport
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##
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let upgrades = newAsyncSemaphore(ConcurrentUpgrades)
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while transport.running:
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var conn: Connection
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try:
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debug "About to accept incoming connection"
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# remember to always release the slot when
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# the upgrade succeeds or fails, this is
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# currently done by the `upgradeMonitor`
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await upgrades.acquire() # first wait for an upgrade slot to become available
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let slot = await s.connManager.getIncomingSlot()
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conn =
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try:
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await transport.accept()
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except CatchableError as exc:
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slot.release()
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raise exc
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slot.trackConnection(conn)
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if isNil(conn):
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# A nil connection means that we might have hit a
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# file-handle limit (or another non-fatal error),
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# we can get one on the next try, but we should
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# be careful to not end up in a thigh loop that
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# will starve the main event loop, thus we sleep
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# here before retrying.
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trace "Unable to get a connection, sleeping"
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await sleepAsync(100.millis) # TODO: should be configurable?
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upgrades.release()
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continue
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# set the direction of this bottom level transport
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# in order to be able to consume this information in gossipsub if required
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# gossipsub gives priority to connections we make
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conn.transportDir = Direction.In
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debug "Accepted an incoming connection", conn
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asyncSpawn upgradeMonitor(conn, upgrades)
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asyncSpawn transport.upgradeIncoming(conn)
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except CancelledError as exc:
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trace "releasing semaphore on cancellation"
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upgrades.release() # always release the slot
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except CatchableError as exc:
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debug "Exception in accept loop, exiting", exc = exc.msg
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upgrades.release() # always release the slot
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if not isNil(conn):
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await conn.close()
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return
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proc stop*(s: Switch) {.async, public.} =
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## Stop listening on every transport, and
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## close every active connections
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trace "Stopping switch"
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s.started = false
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# close and cleanup all connections
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await s.connManager.close()
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for transp in s.transports:
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try:
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await transp.stop()
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except CancelledError as exc:
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raise exc
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except CatchableError as exc:
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warn "error cleaning up transports", msg = exc.msg
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try:
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await allFutures(s.acceptFuts)
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.wait(1.seconds)
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except CatchableError as exc:
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trace "Exception while stopping accept loops", exc = exc.msg
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# check that all futures were properly
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# stopped and otherwise cancel them
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for a in s.acceptFuts:
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if not a.finished:
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a.cancel()
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for service in s.services:
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discard await service.stop(s)
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await s.ms.stop()
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trace "Switch stopped"
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proc start*(s: Switch) {.async, gcsafe, public.} =
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## Start listening on every transport
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if s.started:
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warn "Switch has already been started"
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return
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trace "starting switch for peer", peerInfo = s.peerInfo
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var startFuts: seq[Future[void]]
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for t in s.transports:
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let addrs = s.peerInfo.listenAddrs.filterIt(
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t.handles(it)
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)
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s.peerInfo.listenAddrs.keepItIf(
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it notin addrs
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)
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if addrs.len > 0 or t.running:
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startFuts.add(t.start(addrs))
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await allFutures(startFuts)
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for fut in startFuts:
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if fut.failed:
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await s.stop()
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raise fut.error
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for t in s.transports: # for each transport
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if t.addrs.len > 0 or t.running:
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s.acceptFuts.add(s.accept(t))
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s.peerInfo.listenAddrs &= t.addrs
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await s.peerInfo.update()
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await s.ms.start()
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for service in s.services:
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discard await service.setup(s)
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s.started = true
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debug "Started libp2p node", peer = s.peerInfo
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proc newSwitch*(peerInfo: PeerInfo,
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transports: seq[Transport],
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identity: Identify,
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secureManagers: openArray[Secure] = [],
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connManager: ConnManager,
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ms: MultistreamSelect,
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nameResolver: NameResolver = nil,
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peerStore = PeerStore.new(),
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services = newSeq[Service]()): Switch
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{.raises: [Defect, LPError], public.} =
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if secureManagers.len == 0:
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raise newException(LPError, "Provide at least one secure manager")
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let switch = Switch(
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peerInfo: peerInfo,
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ms: ms,
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transports: transports,
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connManager: connManager,
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peerStore: peerStore,
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dialer: Dialer.new(peerInfo.peerId, connManager, transports, ms, nameResolver),
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nameResolver: nameResolver,
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services: services)
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switch.connManager.peerStore = peerStore
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switch.mount(identity)
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return switch
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