nim-libp2p/libp2p/switch.nim

420 lines
14 KiB
Nim

## 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 tables, sequtils, options, strformat, sets
import chronos, chronicles
import connection,
transports/transport,
multistream,
protocols/protocol,
protocols/secure/secure,
protocols/secure/plaintext, # for plain text
peerinfo,
protocols/identify,
protocols/pubsub/pubsub,
muxers/muxer,
peer
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
NoPubSubException = object of CatchableError
Switch* = ref object of RootObj
peerInfo*: PeerInfo
connections*: Table[string, Connection]
muxed*: Table[string, Muxer]
transports*: seq[Transport]
protocols*: seq[LPProtocol]
muxers*: Table[string, MuxerProvider]
ms*: MultistreamSelect
identity*: Identify
streamHandler*: StreamHandler
secureManagers*: Table[string, Secure]
pubSub*: Option[PubSub]
dialedPubSubPeers: HashSet[string]
proc newNoPubSubException(): ref Exception {.inline.} =
result = newException(NoPubSubException, "no pubsub provided!")
proc secure(s: Switch, conn: Connection): Future[Connection] {.async, gcsafe.} =
## secure the incoming connection
let managers = toSeq(s.secureManagers.keys)
if managers.len == 0:
raise newException(CatchableError, "No secure managers registered!")
let manager = await s.ms.select(conn, toSeq(s.secureManagers.values).mapIt(it.codec))
if manager.len == 0:
raise newException(CatchableError, "Unable to negotiate a secure channel!")
result = await s.secureManagers[manager].secure(conn)
proc identify(s: Switch, conn: Connection): Future[PeerInfo] {.async, gcsafe.} =
## identify the connection
if not isNil(conn.peerInfo):
result = conn.peerInfo
try:
if (await s.ms.select(conn, s.identity.codec)):
let info = await s.identity.identify(conn, conn.peerInfo)
if info.pubKey.isNone and isNil(result):
raise newException(CatchableError,
"no public key provided and no existing peer identity found")
if info.pubKey.isSome:
result = PeerInfo.init(info.pubKey.get())
trace "identify: identified remote peer", peer = result.id
if info.addrs.len > 0:
result.addrs = info.addrs
if info.protos.len > 0:
result.protocols = info.protos
except IdentityInvalidMsgError as exc:
error "identify: invalid message", msg = exc.msg
except IdentityNoMatchError as exc:
error "identify: peer's public keys don't match ", msg = exc.msg
proc mux(s: Switch, conn: Connection): Future[void] {.async, gcsafe.} =
## mux incoming connection
trace "muxing connection"
let muxers = toSeq(s.muxers.keys)
if muxers.len == 0:
warn "no muxers registered, skipping upgrade flow"
return
let muxerName = await s.ms.select(conn, muxers)
if muxerName.len == 0 or muxerName == "na":
return
# create new muxer for connection
let muxer = s.muxers[muxerName].newMuxer(conn)
# install stream handler
muxer.streamHandler = s.streamHandler
# new stream for identify
var stream = await muxer.newStream()
let handlerFut = muxer.handle()
# add muxer handler cleanup proc
handlerFut.addCallback do (udata: pointer = nil):
trace "muxer handler completed for peer",
peer = conn.peerInfo.id
# do identify first, so that we have a
# PeerInfo in case we didn't before
conn.peerInfo = await s.identify(stream)
await stream.close() # close identify stream
trace "connection's peerInfo", peerInfo = $conn.peerInfo
# store it in muxed connections if we have a peer for it
if not isNil(conn.peerInfo):
trace "adding muxer for peer", peer = conn.peerInfo.id
s.muxed[conn.peerInfo.id] = muxer
proc cleanupConn(s: Switch, conn: Connection) {.async, gcsafe.} =
if not isNil(conn.peerInfo):
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:
if not s.connections[id].closed:
await s.connections[id].close()
s.connections.del(id)
s.dialedPubSubPeers.excl(id)
# TODO: Investigate cleanupConn() always called twice for one peer.
if not(conn.peerInfo.isClosed()):
conn.peerInfo.close()
proc disconnect*(s: Switch, peer: PeerInfo) {.async, gcsafe.} =
let conn = s.connections.getOrDefault(peer.id)
if not isNil(conn):
await s.cleanupConn(conn)
proc getMuxedStream(s: Switch, peerInfo: PeerInfo): Future[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]
let conn = await muxer.newStream()
result = conn
proc upgradeOutgoing(s: Switch, conn: Connection): Future[Connection] {.async, gcsafe.} =
trace "handling connection", conn = $conn
result = conn
# don't mux/secure twise
if conn.peerInfo.id in s.muxed:
return
result = await s.secure(result) # secure the connection
if isNil(result):
return
await s.mux(result) # mux it if possible
s.connections[conn.peerInfo.id] = result
proc upgradeIncoming(s: Switch, conn: Connection) {.async, gcsafe.} =
trace "upgrading incoming connection", conn = $conn
let ms = newMultistream()
# 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)
proc subscribeToPeer(s: Switch, peerInfo: PeerInfo) {.async, gcsafe.}
proc internalConnect(s: Switch,
peer: PeerInfo): Future[Connection] {.async.} =
let id = peer.id
trace "Dialing peer", peer = id
var conn = s.connections.getOrDefault(id)
if conn.isNil or conn.closed:
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
trace "Dialing address", address = $a
try:
conn = await t.dial(a)
except CatchableError as exc:
trace "couldn't dial peer, transport failed", exc = exc.msg, address = a
continue
# make sure to assign the peer to the connection
conn.peerInfo = peer
conn = await s.upgradeOutgoing(conn)
if isNil(conn):
continue
conn.closeEvent.wait()
.addCallback do (udata: pointer):
asyncCheck s.cleanupConn(conn)
break
else:
trace "Reusing existing connection"
if not isNil(conn):
await s.subscribeToPeer(peer)
result = conn
proc connect*(s: Switch, peer: PeerInfo) {.async.} =
var conn = await s.internalConnect(peer)
if isNil(conn):
raise newException(CatchableError, "Unable to connect to peer")
proc dial*(s: Switch,
peer: PeerInfo,
proto: string):
Future[Connection] {.async.} =
var conn = await s.internalConnect(peer)
if isNil(conn):
raise newException(CatchableError, "Unable to establish outgoing link")
if conn.closed:
raise newException(CatchableError, "Connection dead on arrival")
result = conn
let stream = await s.getMuxedStream(peer)
if not isNil(stream):
trace "Connection is muxed, return muxed stream"
result = stream
trace "Attempting to select remote", proto = proto
if not await s.ms.select(result, proto):
warn "Unable to select sub-protocol", proto = proto
raise newException(CatchableError, &"unable to select protocol: {proto}")
proc mount*[T: LPProtocol](s: Switch, proto: T) {.gcsafe.} =
if isNil(proto.handler):
raise newException(CatchableError,
"Protocol has to define a handle method or proc")
if proto.codec.len == 0:
raise newException(CatchableError,
"Protocol has to define a codec string")
s.ms.addHandler(proto.codec, proto)
proc start*(s: Switch): Future[seq[Future[void]]] {.async, gcsafe.} =
trace "starting switch"
proc handle(conn: Connection): Future[void] {.async, closure, gcsafe.} =
try:
await s.upgradeIncoming(conn) # perform upgrade on incoming connection
except CatchableError as exc:
trace "Exception occurred in Switch.start", exc = exc.msg
finally:
if not isNil(conn) and not conn.closed:
await conn.close()
await s.cleanupConn(conn)
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 = await t.listen(a, handle)
s.peerInfo.addrs[i] = t.ma # update peer's address
startFuts.add(server)
if s.pubSub.isSome:
await s.pubSub.get().start()
result = startFuts # listen for incoming connections
proc stop*(s: Switch) {.async.} =
trace "stopping switch"
if s.pubSub.isSome:
await s.pubSub.get().stop()
await allFutures(toSeq(s.connections.values).mapIt(s.cleanupConn(it)))
await allFutures(s.transports.mapIt(it.close()))
proc subscribeToPeer(s: Switch, peerInfo: PeerInfo) {.async, gcsafe.} =
## Subscribe to pub sub peer
if s.pubSub.isSome and peerInfo.id notin s.dialedPubSubPeers:
try:
s.dialedPubSubPeers.incl(peerInfo.id)
let conn = await s.dial(peerInfo, s.pubSub.get().codec)
await s.pubSub.get().subscribeToPeer(conn)
except CatchableError as exc:
warn "unable to initiate pubsub", exc = exc.msg
finally:
s.dialedPubSubPeers.excl(peerInfo.id)
proc subscribe*(s: Switch, topic: string,
handler: TopicHandler): Future[void] =
## subscribe to a pubsub topic
if s.pubSub.isNone:
var retFuture = newFuture[void]("Switch.subscribe")
retFuture.fail(newNoPubSubException())
return retFuture
result = s.pubSub.get().subscribe(topic, handler)
proc unsubscribe*(s: Switch, topics: seq[TopicPair]): Future[void] =
## unsubscribe from topics
if s.pubSub.isNone:
var retFuture = newFuture[void]("Switch.unsubscribe")
retFuture.fail(newNoPubSubException())
return retFuture
result = s.pubSub.get().unsubscribe(topics)
proc publish*(s: Switch, topic: string, data: seq[byte]): Future[void] =
# pubslish to pubsub topic
if s.pubSub.isNone:
var retFuture = newFuture[void]("Switch.publish")
retFuture.fail(newNoPubSubException())
return retFuture
result = s.pubSub.get().publish(topic, data)
proc addValidator*(s: Switch,
topics: varargs[string],
hook: ValidatorHandler) =
# add validator
if s.pubSub.isNone:
raise newNoPubSubException()
s.pubSub.get().addValidator(topics, hook)
proc removeValidator*(s: Switch,
topics: varargs[string],
hook: ValidatorHandler) =
# pubslish to pubsub topic
if s.pubSub.isNone:
raise newNoPubSubException()
s.pubSub.get().removeValidator(topics, hook)
proc newSwitch*(peerInfo: PeerInfo,
transports: seq[Transport],
identity: Identify,
muxers: Table[string, MuxerProvider],
secureManagers: Table[string, Secure] = initTable[string, Secure](),
pubSub: Option[PubSub] = none(PubSub)): Switch =
new result
result.peerInfo = peerInfo
result.ms = newMultistream()
result.transports = transports
result.connections = initTable[string, Connection]()
result.muxed = initTable[string, Muxer]()
result.identity = identity
result.muxers = muxers
result.secureManagers = initTable[string, Secure]()
result.dialedPubSubPeers = initHashSet[string]()
let s = result # can't capture result
result.streamHandler = proc(stream: Connection) {.async, gcsafe.} =
trace "handling connection for", peerInfo = $stream.peerInfo
await s.ms.handle(stream) # handle incoming connection
result.mount(identity)
for key, val in muxers:
val.streamHandler = result.streamHandler
val.muxerHandler = proc(muxer: Muxer) {.async, gcsafe.} =
trace "got new muxer"
let stream = await muxer.newStream()
muxer.connection.peerInfo = await s.identify(stream)
await stream.close()
for k in secureManagers.keys:
trace "adding secure manager ", codec = secureManagers[k].codec
result.secureManagers[k] = secureManagers[k]
if result.secureManagers.len == 0:
# use plain text if no secure managers are provided
warn "no secure managers, falling back to plain text", codec = PlainTextCodec
result.secureManagers[PlainTextCodec] = Secure(newPlainText())
if pubSub.isSome:
result.pubSub = pubSub
result.mount(pubSub.get())