nim-libp2p/libp2p/switch.nim

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## Nim-LibP2P
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## Copyright (c) 2019 Status Research & Development GmbH
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## 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,
multistream,
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protocols/protocol,
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protocols/secure/secure,
protocols/secure/plaintext, # for plain text
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peerinfo,
protocols/identify,
protocols/pubsub/pubsub,
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muxers/muxer,
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peer
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logScope:
topic = "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)
type
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NoPubSubException = object of CatchableError
Switch* = ref object of RootObj
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peerInfo*: PeerInfo
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connections*: Table[string, Connection]
muxed*: Table[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*: Table[string, 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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let managers = toSeq(s.secureManagers.keys)
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if managers.len == 0:
raise newException(CatchableError, "No secure managers registered!")
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let manager = await s.ms.select(conn, toSeq(s.secureManagers.values).mapIt(it.codec))
if manager.len == 0:
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raise newException(CatchableError, "Unable to negotiate a secure channel!")
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result = await s.secureManagers[manager].secure(conn)
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proc identify(s: Switch, conn: Connection): Future[PeerInfo] {.async, gcsafe.} =
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## identify the connection
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result = conn.peerInfo
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try:
if (await s.ms.select(conn, s.identity.codec)):
let info = await s.identity.identify(conn, conn.peerInfo)
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if info.pubKey.isSome:
result.peerId = some(PeerID.init(info.pubKey.get())) # we might not have a peerId at all
trace "identify: identified remote peer", peer = result.id
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if info.addrs.len > 0:
result.addrs = info.addrs
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if info.protos.len > 0:
result.protocols = info.protos
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except IdentityInvalidMsgError as exc:
error "identify: invalid message", msg = exc.msg
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except IdentityNoMatchError as exc:
error "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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trace "muxing connection"
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let muxers = toSeq(s.muxers.keys)
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if muxers.len == 0:
warn "no muxers registered, skipping upgrade flow"
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return
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let muxerName = await s.ms.select(conn, muxers)
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if muxerName.len == 0 or muxerName == "na":
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return
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# create new muxer for connection
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let muxer = s.muxers[muxerName].newMuxer(conn)
# install stream handler
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muxer.streamHandler = s.streamHandler
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# new stream for identify
var stream = await muxer.newStream()
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let handlerFut = muxer.handle()
# add muxer handler cleanup proc
handlerFut.addCallback(
proc(udata: pointer = nil) {.gcsafe.} =
trace "muxer handler completed for peer",
peer = conn.peerInfo.id
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)
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# do identify first, so that we have a
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# PeerInfo in case we didn't before
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conn.peerInfo = await s.identify(stream)
await stream.close() # close identify stream
trace "connection's peerInfo", peerInfo = conn.peerInfo
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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:
trace "adding muxer for peer", peer = conn.peerInfo.id
s.muxed[conn.peerInfo.id] = muxer
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proc cleanupConn(s: Switch, conn: Connection) {.async, gcsafe.} =
if conn.peerInfo.peerId.isSome:
let id = conn.peerInfo.id
trace "cleaning up connection for peer", peerId = id
if id in s.muxed:
await s.muxed[id].close()
s.muxed.del(id)
if id in s.connections:
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await s.connections[id].close()
s.connections.del(id)
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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 peerInfo.id in s.muxed:
trace "connection is muxed, setting up a stream"
let muxer = s.muxed[peerInfo.id]
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let conn = await muxer.newStream()
result = some(conn)
proc upgradeOutgoing(s: Switch, conn: Connection): Future[Connection] {.async, gcsafe.} =
trace "handling connection", conn = conn
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result = conn
# don't mux/secure twise
if conn.peerInfo.peerId.isSome and
conn.peerInfo.id in s.muxed:
return
result = await s.secure(result) # secure the connection
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await s.mux(result) # mux it if possible
s.connections[conn.peerInfo.id] = result
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proc upgradeIncoming(s: Switch, conn: Connection) {.async, gcsafe.} =
trace "upgrading incoming connection"
let ms = newMultistream()
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# secure incoming connections
proc securedHandler (conn: Connection,
proto: string)
{.async, gcsafe, closure.} =
trace "Securing connection"
let secure = s.secureManagers[proto]
let sconn = await secure.secure(conn)
if not isNil(sconn):
# add the muxer
for muxer in s.muxers.values:
ms.addHandler(muxer.codec, muxer)
# handle subsequent requests
await ms.handle(sconn)
if (await ms.select(conn)): # just handshake
# add the secure handlers
for k in s.secureManagers.keys:
ms.addHandler(k, securedHandler)
# handle secured connections
await ms.handle(conn)
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proc dial*(s: Switch,
peer: PeerInfo,
proto: string = ""):
Future[Connection] {.async.} =
let id = peer.id
trace "dialing peer", peer = id
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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
if id notin s.connections:
trace "dialing address", address = $a
result = await t.dial(a)
# make sure to assign the peer to the connection
result.peerInfo = peer
result = await s.upgradeOutgoing(result)
result.closeEvent.wait().addCallback(
proc(udata: pointer) =
asyncCheck s.cleanupConn(result)
)
if proto.len > 0 and not result.closed:
let stream = await s.getMuxedStream(peer)
if stream.isSome:
trace "connection is muxed, return muxed stream"
result = stream.get()
trace "attempting to select remote", proto = proto
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if not (await s.ms.select(result, proto)):
error "unable to select protocol: ", proto = proto
raise newException(CatchableError,
&"unable to select protocol: {proto}")
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break # don't dial more than one addr on the same transport
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proc mount*[T: LPProtocol](s: Switch, proto: T) {.gcsafe.} =
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if isNil(proto.handler):
raise newException(CatchableError,
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"Protocol has to define a handle method or proc")
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if proto.codec.len == 0:
raise newException(CatchableError,
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"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, gcsafe.} =
trace "starting switch"
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proc handle(conn: Connection): Future[void] {.async, closure, gcsafe.} =
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try:
await s.upgradeIncoming(conn) # perform upgrade on incoming connection
except CatchableError as exc:
trace "exception occured", exc = exc.msg
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finally:
await conn.close()
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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
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for i, a in s.peerInfo.addrs:
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if t.handles(a): # check if it handles the multiaddr
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var server = await t.listen(a, handle)
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s.peerInfo.addrs[i] = t.ma # update peer's address
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startFuts.add(server)
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result = startFuts # listen for incoming connections
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proc stop*(s: Switch) {.async.} =
trace "stopping switch"
await allFutures(toSeq(s.connections.values).mapIt(s.cleanupConn(it)))
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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()
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result = s.pubSub.get().subscribe(topic, handler)
proc unsubscribe*(s: Switch, topics: seq[TopicPair]): Future[void] {.gcsafe.} =
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## unsubscribe from topics
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if s.pubSub.isNone:
raise newNoPubSubException()
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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: Table[string, Secure] = initTable[string, Secure](),
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pubSub: Option[PubSub] = none(PubSub)): Switch =
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new result
result.peerInfo = peerInfo
result.ms = newMultistream()
result.transports = transports
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result.connections = initTable[string, Connection]()
result.muxed = initTable[string, Muxer]()
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result.identity = identity
result.muxers = muxers
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result.secureManagers = initTable[string, Secure]()
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let s = result # can't capture result
result.streamHandler = proc(stream: Connection) {.async, gcsafe.} =
trace "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.} =
trace "got new muxer"
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let stream = await muxer.newStream()
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muxer.connection.peerInfo = await s.identify(stream)
await stream.close()
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for k in secureManagers.keys:
trace "adding secure manager ", codec = secureManagers[k].codec
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result.secureManagers[k] = secureManagers[k]
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if result.secureManagers.len == 0:
# use plain text if no secure managers are provided
warn "no secure managers, falling back to palin text", codec = PlainTextCodec
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result.secureManagers[PlainTextCodec] = Secure(newPlainText())
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if pubSub.isSome:
result.pubSub = pubSub
result.mount(pubSub.get())