nim-libp2p-experimental/libp2p/switch.nim

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## Nim-LibP2P
## Copyright (c) 2018 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.
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import tables, sequtils, options, strformat
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import chronos, chronicles
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import connection,
transports/transport,
stream/lpstream,
multistream,
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protocols/protocol,
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protocols/secure/secure, # for plain text
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peerinfo,
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multiaddress,
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protocols/identify,
protocols/pubsub/pubsub,
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muxers/muxer,
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peer
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logScope:
topic = "Switch"
type
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NoPubSubException = object of CatchableError
Switch* = ref object of RootObj
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peerInfo*: PeerInfo
connections*: TableRef[string, Connection]
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muxed*: TableRef[string, Muxer]
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transports*: seq[Transport]
protocols*: seq[LPProtocol]
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muxers*: Table[string, MuxerProvider]
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ms*: MultisteamSelect
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identity*: Identify
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streamHandler*: StreamHandler
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secureManagers*: seq[Secure]
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pubSub*: Option[PubSub]
proc newNoPubSubException(): ref Exception {.inline.} =
result = newException(NoPubSubException, "no pubsub provided!")
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proc secure(s: Switch, conn: Connection): Future[Connection] {.async, gcsafe.} =
## secure the incoming connection
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# plaintext for now, doesn't do anything
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let managers = s.secureManagers.mapIt(it.codec).deduplicate()
if managers.len == 0:
raise newException(CatchableError, "No secure managers registered!")
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if (await s.ms.select(conn, s.secureManagers.mapIt(it.codec))).len == 0:
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raise newException(CatchableError, "Unable to negotiate a secure channel!")
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var n = await s.secureManagers[0].secure(conn)
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result = conn
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proc identify*(s: Switch, conn: Connection) {.async, gcsafe.} =
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## identify the connection
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# s.peerInfo.protocols = await s.ms.list(conn) # update protos before engagin in identify
try:
if (await s.ms.select(conn, s.identity.codec)):
let info = await s.identity.identify(conn, conn.peerInfo)
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let id = if conn.peerInfo.peerId.isSome:
conn.peerInfo.peerId.get().pretty
else:
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""
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if id.len > 0 and s.connections.contains(id):
let connection = s.connections[id]
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var peerInfo = conn.peerInfo
if info.pubKey.isSome:
peerInfo.peerId = some(PeerID.init(info.pubKey.get())) # we might not have a peerId at all
if info.addrs.len > 0:
peerInfo.addrs = info.addrs
if info.protos.len > 0:
peerInfo.protocols = info.protos
debug "identify: identified remote peer ", peer = peerInfo.peerId.get().pretty
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except IdentityInvalidMsgError as exc:
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debug "identify: invalid message", msg = exc.msg
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except IdentityNoMatchError as exc:
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debug "identify: peer's public keys don't match ", msg = exc.msg
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proc mux(s: Switch, conn: Connection): Future[void] {.async, gcsafe.} =
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## mux incoming connection
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let muxers = toSeq(s.muxers.keys)
let muxerName = await s.ms.select(conn, muxers)
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if muxerName.len == 0 or muxerName == "na":
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return
let muxer = s.muxers[muxerName].newMuxer(conn)
# install stream handler
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muxer.streamHandler = s.streamHandler
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# do identify first, so that we have a
# PeerInfo in case we didn't before
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let stream = await muxer.newStream()
let handlerFut = muxer.handle()
# add muxer handler cleanup proc
handlerFut.addCallback(
proc(udata: pointer = nil) {.gcsafe.} =
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debug "mux: Muxer handler completed for peer ",
peer = conn.peerInfo.peerId.get().pretty
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)
await s.identify(stream)
await stream.close() # close idenity stream
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# store it in muxed connections if we have a peer for it
# TODO: We should make sure that this are cleaned up properly
# on exit even if there is no peer for it. This shouldn't
# happen once secio is in place, but still something to keep
# in mind
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if conn.peerInfo.peerId.isSome:
s.muxed[conn.peerInfo.peerId.get().pretty] = muxer
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proc handleConn(s: Switch, conn: Connection): Future[Connection] {.async, gcsafe.} =
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result = conn
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## perform upgrade flow
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if result.peerInfo.peerId.isSome:
let id = result.peerInfo.peerId.get().pretty
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if s.connections.contains(id):
# if we already have a connection for this peer,
# close the incoming connection and return the
# existing one
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await result.close()
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return s.connections[id]
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s.connections[id] = result
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result = await s.secure(conn) # secure the connection
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await s.mux(result) # mux it if possible
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proc cleanupConn(s: Switch, conn: Connection) {.async, gcsafe.} =
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if conn.peerInfo.peerId.isSome:
let id = conn.peerInfo.peerId.get().pretty
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if s.muxed.contains(id):
await s.muxed[id].close
if s.connections.contains(id):
await s.connections[id].close()
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proc getMuxedStream(s: Switch, peerInfo: PeerInfo): Future[Option[Connection]] {.async, gcsafe.} =
# if there is a muxer for the connection
# use it instead to create a muxed stream
if s.muxed.contains(peerInfo.peerId.get().pretty):
let muxer = s.muxed[peerInfo.peerId.get().pretty]
let conn = await muxer.newStream()
result = some(conn)
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proc dial*(s: Switch,
peer: PeerInfo,
proto: string = ""):
Future[Connection] {.async.} =
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for t in s.transports: # for each transport
for a in peer.addrs: # for each address
if t.handles(a): # check if it can dial it
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result = await t.dial(a)
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# make sure to assign the peer to the connection
result.peerInfo = peer
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result = await s.handleConn(result)
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let stream = await s.getMuxedStream(peer)
if stream.isSome:
result = stream.get()
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debug "dial: attempting to select remote ", proto = proto
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if not (await s.ms.select(result, proto)):
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debug "dial: Unable to select protocol: ", proto = proto
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raise newException(CatchableError,
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&"Unable to select protocol: {proto}")
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proc mount*[T: LPProtocol](s: Switch, proto: T) {.gcsafe.} =
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if isNil(proto.handler):
raise newException(CatchableError,
"Protocol has to define a handle method or proc")
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if proto.codec.len == 0:
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raise newException(CatchableError,
"Protocol has to define a codec string")
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s.ms.addHandler(proto.codec, proto)
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proc start*(s: Switch): Future[seq[Future[void]]] {.async.} =
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proc handle(conn: Connection): Future[void] {.async, closure, gcsafe.} =
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try:
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if (await s.ms.select(conn)): # just handshake
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await s.ms.handle(conn) # handle incoming connection
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except:
await s.cleanupConn(conn)
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var startFuts: seq[Future[void]]
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for t in s.transports: # for each transport
for a in s.peerInfo.addrs:
if t.handles(a): # check if it handles the multiaddr
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var server = await t.listen(a, handle)
startFuts.add(server)
result = startFuts # listen for incoming connections
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proc stop*(s: Switch) {.async.} =
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await allFutures(s.transports.mapIt(it.close()))
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proc subscribeToPeer*(s: Switch, peerInfo: PeerInfo) {.async, gcsafe.} =
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## Subscribe to pub sub peer
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if s.pubSub.isSome:
let conn = await s.dial(peerInfo, s.pubSub.get().codec)
await s.pubSub.get().subscribeToPeer(conn)
proc subscribe*(s: Switch, topic: string, handler: TopicHandler): Future[void] {.gcsafe.} =
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## subscribe to a pubsub topic
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if s.pubSub.isNone:
raise newNoPubSubException()
result = s.pubSub.get().subscribe(topic, handler)
proc unsubscribe*(s: Switch, topics: seq[string]): Future[void] {.gcsafe.} =
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## unsubscribe from topics
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if s.pubSub.isNone:
raise newNoPubSubException()
result = s.pubSub.get().unsubscribe(topics)
proc publish*(s: Switch, topic: string, data: seq[byte]): Future[void] {.gcsafe.} =
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# pubslish to pubsub topic
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if s.pubSub.isNone:
raise newNoPubSubException()
result = s.pubSub.get().publish(topic, data)
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proc newSwitch*(peerInfo: PeerInfo,
transports: seq[Transport],
identity: Identify,
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muxers: Table[string, MuxerProvider],
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secureManagers: seq[Secure] = @[],
pubSub: Option[PubSub] = none(PubSub)): Switch =
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new result
result.peerInfo = peerInfo
result.ms = newMultistream()
result.transports = transports
result.connections = newTable[string, Connection]()
result.muxed = newTable[string, Muxer]()
result.identity = identity
result.muxers = muxers
let s = result # can't capture result
result.streamHandler = proc(stream: Connection) {.async, gcsafe.} =
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debug "handling connection for", peerInfo = stream.peerInfo
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await s.ms.handle(stream) # handle incoming connection
result.mount(identity)
for key, val in muxers:
val.streamHandler = result.streamHandler
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val.muxerHandler = proc(muxer: Muxer) {.async, gcsafe.} =
debug "got new muxer"
let stream = await muxer.newStream()
await s.identify(stream)
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result.mount(val)
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for s in secureManagers.deduplicate():
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debug "adding secure manager ", codec = s.codec
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result.secureManagers.add(s)
result.mount(s)
if result.secureManagers.len == 0:
# use plain text if no secure managers are provided
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let manager = Secure(newPlainText())
result.mount(manager)
result.secureManagers.add(manager)
result.secureManagers = result.secureManagers.deduplicate()
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if pubSub.isSome:
result.pubSub = pubSub
result.mount(pubSub.get())