nim-libp2p/libp2p/switch.nim

716 lines
21 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,
algorithm,
oids
import chronos,
chronicles,
metrics
import stream/connection,
stream/chronosstream,
transports/transport,
multistream,
multiaddress,
protocols/protocol,
protocols/secure/secure,
protocols/secure/plaintext, # for plain text
peerinfo,
protocols/identify,
protocols/pubsub/pubsub,
muxers/muxer,
errors,
peerid
logScope:
topics = "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)
declareGauge(libp2p_peers, "total connected peers")
declareCounter(libp2p_dialed_peers, "dialed peers")
declareCounter(libp2p_failed_dials, "failed dials")
declareCounter(libp2p_failed_upgrade, "peers failed upgrade")
const MaxConnectionsPerPeer = 5
type
NoPubSubException* = object of CatchableError
TooManyConnections* = object of CatchableError
Direction {.pure.} = enum
In, Out
ConnectionHolder = object
dir: Direction
conn: Connection
MuxerHolder = object
dir: Direction
muxer: Muxer
handle: Future[void]
Switch* = ref object of RootObj
peerInfo*: PeerInfo
connections*: Table[string, seq[ConnectionHolder]]
muxed*: Table[string, seq[MuxerHolder]]
transports*: seq[Transport]
protocols*: seq[LPProtocol]
muxers*: Table[string, MuxerProvider]
ms*: MultistreamSelect
identity*: Identify
streamHandler*: StreamHandler
secureManagers*: seq[Secure]
pubSub*: Option[PubSub]
dialLock: Table[string, AsyncLock]
cleanUpLock: Table[string, AsyncLock]
proc newNoPubSubException(): ref NoPubSubException {.inline.} =
result = newException(NoPubSubException, "no pubsub provided!")
proc newTooManyConnections(): ref TooManyConnections {.inline.} =
result = newException(TooManyConnections, "too many connections for peer")
proc disconnect*(s: Switch, peer: PeerInfo) {.async, gcsafe.}
proc subscribePeer*(s: Switch, peerInfo: PeerInfo) {.async, gcsafe.}
proc selectConn(s: Switch, peerInfo: PeerInfo): Connection =
## select the "best" connection according to some criteria
##
## Ideally when the connection's stats are available
## we'd select the fastest, but for now we simply pick an outgoing
## connection first if none is available, we pick the first outgoing
##
if isNil(peerInfo):
return
let conns = s.connections
.getOrDefault(peerInfo.id)
# it should be OK to sort on each
# access as there should only be
# up to MaxConnectionsPerPeer entries
.sorted(
proc(a, b: ConnectionHolder): int =
if a.dir < b.dir: -1
elif a.dir == b.dir: 0
else: 1
, SortOrder.Descending)
if conns.len > 0:
return conns[0].conn
proc selectMuxer(s: Switch, conn: Connection): Muxer =
## select the muxer for the supplied connection
##
if isNil(conn):
return
if not(isNil(conn.peerInfo)) and conn.peerInfo.id in s.muxed:
if s.muxed[conn.peerInfo.id].len > 0:
let muxers = s.muxed[conn.peerInfo.id]
.filterIt( it.muxer.connection == conn )
if muxers.len > 0:
return muxers[0].muxer
proc storeConn(s: Switch,
muxer: Muxer,
dir: Direction,
handle: Future[void] = nil) {.async.} =
## store the connection and muxer
##
if isNil(muxer):
return
let conn = muxer.connection
if isNil(conn):
return
let id = conn.peerInfo.id
if s.connections.getOrDefault(id).len > MaxConnectionsPerPeer:
warn "disconnecting peer, too many connections", peer = $conn.peerInfo,
conns = s.connections
.getOrDefault(id).len
await s.disconnect(conn.peerInfo)
raise newTooManyConnections()
s.connections.mgetOrPut(
id,
newSeq[ConnectionHolder]())
.add(ConnectionHolder(conn: conn, dir: dir))
s.muxed.mgetOrPut(
muxer.connection.peerInfo.id,
newSeq[MuxerHolder]())
.add(MuxerHolder(muxer: muxer, handle: handle, dir: dir))
trace "storred connection", connections = s.connections.len
libp2p_peers.set(s.connections.len.int64)
proc secure(s: Switch, conn: Connection): Future[Connection] {.async, gcsafe.} =
if s.secureManagers.len <= 0:
raise newException(CatchableError, "No secure managers registered!")
let manager = await s.ms.select(conn, s.secureManagers.mapIt(it.codec))
if manager.len == 0:
raise newException(CatchableError, "Unable to negotiate a secure channel!")
trace "securing connection", codec = manager
let secureProtocol = s.secureManagers.filterIt(it.codec == manager)
# ms.select should deal with the correctness of this
# let's avoid duplicating checks but detect if it fails to do it properly
doAssert(secureProtocol.len > 0)
result = await secureProtocol[0].secure(conn, true)
proc identify(s: Switch, conn: Connection) {.async, gcsafe.} =
## identify the connection
if (await s.ms.select(conn, s.identity.codec)):
let info = await s.identity.identify(conn, conn.peerInfo)
if info.pubKey.isNone and isNil(conn):
raise newException(CatchableError,
"no public key provided and no existing peer identity found")
if isNil(conn.peerInfo):
conn.peerInfo = PeerInfo.init(info.pubKey.get())
if info.addrs.len > 0:
conn.peerInfo.addrs = info.addrs
if info.agentVersion.isSome:
conn.peerInfo.agentVersion = info.agentVersion.get()
if info.protoVersion.isSome:
conn.peerInfo.protoVersion = info.protoVersion.get()
if info.protos.len > 0:
conn.peerInfo.protocols = info.protos
trace "identify: identified remote peer", peer = $conn.peerInfo
proc mux(s: Switch, conn: Connection) {.async, gcsafe.} =
## mux incoming connection
trace "muxing connection", peer = $conn
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":
debug "no muxer available, early exit", peer = $conn
return
# create new muxer for connection
let muxer = s.muxers[muxerName].newMuxer(conn)
trace "found a muxer", name = muxerName, peer = $conn
# install stream handler
muxer.streamHandler = s.streamHandler
# new stream for identify
var stream = await muxer.newStream()
var handlerFut: Future[void]
defer:
if not(isNil(stream)):
await stream.close() # close identify stream
# call muxer handler, this should
# not end until muxer ends
handlerFut = muxer.handle()
# do identify first, so that we have a
# PeerInfo in case we didn't before
await s.identify(stream)
if isNil(conn.peerInfo):
await muxer.close()
raise newException(CatchableError,
"unable to identify peer, aborting upgrade")
# store it in muxed connections if we have a peer for it
trace "adding muxer for peer", peer = conn.peerInfo.id
await s.storeConn(muxer, Direction.Out, handlerFut)
proc cleanupConn(s: Switch, conn: Connection) {.async, gcsafe.} =
if isNil(conn):
return
if isNil(conn.peerInfo):
return
let id = conn.peerInfo.id
let lock = s.cleanUpLock.mgetOrPut(id, newAsyncLock())
try:
await lock.acquire()
trace "cleaning up connection for peer", peerId = id
if id in s.muxed:
let muxerHolder = s.muxed[id]
.filterIt(
it.muxer.connection == conn
)
if muxerHolder.len > 0:
await muxerHolder[0].muxer.close()
if not(isNil(muxerHolder[0].handle)):
await muxerHolder[0].handle
if id in s.muxed:
s.muxed[id].keepItIf(
it.muxer.connection != conn
)
if s.muxed[id].len == 0:
s.muxed.del(id)
if s.pubSub.isSome:
await s.pubSub.get()
.unsubscribePeer(conn.peerInfo)
if id in s.connections:
s.connections[id].keepItIf(
it.conn != conn
)
if s.connections[id].len == 0:
s.connections.del(id)
# TODO: Investigate cleanupConn() always called twice for one peer.
if not(conn.peerInfo.isClosed()):
conn.peerInfo.close()
finally:
await conn.close()
libp2p_peers.set(s.connections.len.int64)
if lock.locked():
lock.release()
proc disconnect*(s: Switch, peer: PeerInfo) {.async, gcsafe.} =
let connections = s.connections.getOrDefault(peer.id)
for connHolder in connections:
if not isNil(connHolder.conn):
await s.cleanupConn(connHolder.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
let muxer = s.selectMuxer(s.selectConn(peerInfo)) # always get the first muxer here
if not(isNil(muxer)):
return await muxer.newStream()
proc upgradeOutgoing(s: Switch, conn: Connection): Future[Connection] {.async, gcsafe.} =
logScope:
conn = $conn
oid = $conn.oid
let sconn = await s.secure(conn) # secure the connection
if isNil(sconn):
raise newException(CatchableError,
"unable to secure connection, stopping upgrade")
trace "upgrading connection"
await s.mux(sconn) # mux it if possible
if isNil(sconn.peerInfo):
await sconn.close()
raise newException(CatchableError,
"unable to mux connection, stopping upgrade")
trace "succesfully upgraded outgoing connection", uoid = sconn.oid
return sconn
proc upgradeIncoming(s: Switch, conn: Connection) {.async, gcsafe.} =
trace "upgrading incoming connection", conn = $conn, oid = conn.oid
let ms = newMultistream()
# secure incoming connections
proc securedHandler (conn: Connection,
proto: string)
{.async, gcsafe, closure.} =
var sconn: Connection
trace "Securing connection", oid = conn.oid
let secure = s.secureManagers.filterIt(it.codec == proto)[0]
try:
sconn = await secure.secure(conn, false)
if isNil(sconn):
return
defer:
await sconn.close()
# add the muxer
for muxer in s.muxers.values:
ms.addHandler(muxer.codec, muxer)
# handle subsequent requests
await ms.handle(sconn)
except CancelledError as exc:
raise exc
except CatchableError as exc:
debug "ending secured handler", err = exc.msg
if (await ms.select(conn)): # just handshake
# add the secure handlers
for k in s.secureManagers:
ms.addHandler(k.codec, securedHandler)
# handle secured connections
await ms.handle(conn)
proc internalConnect(s: Switch,
peer: PeerInfo): Future[Connection] {.async.} =
if s.peerInfo.peerId == peer.peerId:
raise newException(CatchableError, "can't dial self!")
let id = peer.id
var conn: Connection
let lock = s.dialLock.mgetOrPut(id, newAsyncLock())
defer:
if lock.locked():
lock.release()
await lock.acquire()
trace "about to dial peer", peer = id
conn = s.selectConn(peer)
if conn.isNil or conn.closed:
trace "Dialing peer", peer = id
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)
libp2p_dialed_peers.inc()
except CancelledError as exc:
trace "dialing canceled", exc = exc.msg
raise
except CatchableError as exc:
trace "dialing failed", exc = exc.msg
libp2p_failed_dials.inc()
continue
# make sure to assign the peer to the connection
conn.peerInfo = peer
try:
conn = await s.upgradeOutgoing(conn)
except CatchableError as exc:
if not(isNil(conn)):
await conn.close()
trace "Unable to establish outgoing link", exc = exc.msg
raise exc
if isNil(conn):
libp2p_failed_upgrade.inc()
continue
conn.closeEvent.wait()
.addCallback do(udata: pointer):
asyncCheck s.cleanupConn(conn)
break
else:
trace "Reusing existing connection", oid = conn.oid
if isNil(conn):
raise newException(CatchableError,
"Unable to establish outgoing link")
if conn.closed or conn.atEof:
await conn.close()
raise newException(CatchableError,
"Connection dead on arrival")
doAssert(conn.peerInfo.id in s.connections,
"connection not tracked!")
trace "dial succesfull", oid = $conn.oid,
peer = $conn.peerInfo
await s.subscribePeer(peer)
return conn
proc connect*(s: Switch, peer: PeerInfo) {.async.} =
discard await s.internalConnect(peer)
proc dial*(s: Switch,
peer: PeerInfo,
proto: string):
Future[Connection] {.async.} =
let conn = await s.internalConnect(peer)
let stream = await s.getMuxedStream(peer)
proc cleanup() {.async.} =
if not(isNil(stream)):
await stream.close()
if not(isNil(conn)):
await conn.close()
try:
if isNil(stream):
await conn.close()
raise newException(CatchableError, "Couldn't get muxed stream")
trace "Attempting to select remote", proto = proto, oid = conn.oid
if not await s.ms.select(stream, proto):
await stream.close()
raise newException(CatchableError, "Unable to select sub-protocol " & proto)
return stream
except CancelledError as exc:
trace "dial canceled"
await cleanup()
raise exc
except CatchableError as exc:
trace "error dialing"
await cleanup()
raise exc
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 for peer", peerInfo = shortLog(s.peerInfo)
proc handle(conn: Connection): Future[void] {.async, closure, gcsafe.} =
try:
defer:
await s.cleanupConn(conn)
await s.upgradeIncoming(conn) # perform upgrade on incoming connection
except CancelledError as exc:
raise exc
except CatchableError as exc:
trace "Exception occurred in Switch.start", exc = exc.msg
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()
info "started libp2p node", peer = $s.peerInfo, addrs = s.peerInfo.addrs
result = startFuts # listen for incoming connections
proc stop*(s: Switch) {.async.} =
trace "stopping switch"
# we want to report errors but we do not want to fail
# or crash here, cos we need to clean possibly MANY items
# and any following conn/transport won't be cleaned up
if s.pubSub.isSome:
await s.pubSub.get().stop()
for conns in toSeq(s.connections.values):
for conn in conns:
try:
await s.cleanupConn(conn.conn)
except CancelledError as exc:
raise exc
except CatchableError as exc:
warn "error cleaning up connections"
for t in s.transports:
try:
await t.close()
except CancelledError as exc:
raise exc
except CatchableError as exc:
warn "error cleaning up transports"
trace "switch stopped"
proc subscribePeer*(s: Switch, peerInfo: PeerInfo) {.async, gcsafe.} =
## Subscribe to pub sub peer
if s.pubSub.isSome and not(s.pubSub.get().connected(peerInfo)):
trace "about to subscribe to pubsub peer", peer = peerInfo.shortLog()
var stream: Connection
try:
stream = await s.getMuxedStream(peerInfo)
except CancelledError as exc:
if not(isNil(stream)):
await stream.close()
raise exc
except CatchableError as exc:
trace "exception in subscribe to peer", peer = peerInfo.shortLog,
exc = exc.msg
if not(isNil(stream)):
await stream.close()
if isNil(stream):
trace "unable to subscribe to peer", peer = peerInfo.shortLog
return
if not await s.ms.select(stream, s.pubSub.get().codec):
if not(isNil(stream)):
await stream.close()
return
s.pubSub.get().subscribePeer(stream)
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
return 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
return s.pubSub.get().unsubscribe(topics)
proc publish*(s: Switch, topic: string, data: seq[byte]): Future[int] =
# pubslish to pubsub topic
if s.pubSub.isNone:
var retFuture = newFuture[int]("Switch.publish")
retFuture.fail(newNoPubSubException())
return retFuture
return 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 muxerHandler(s: Switch, muxer: Muxer) {.async, gcsafe.} =
var stream = await muxer.newStream()
defer:
if not(isNil(stream)):
await stream.close()
try:
# once we got a muxed connection, attempt to
# identify it
await s.identify(stream)
if isNil(stream.peerInfo):
await muxer.close()
return
muxer.connection.peerInfo = stream.peerInfo
# store muxer and muxed connection
await s.storeConn(muxer, Direction.In)
muxer.connection.closeEvent.wait()
.addCallback do(udata: pointer):
asyncCheck s.cleanupConn(muxer.connection)
trace "got new muxer", peer = $muxer.connection.peerInfo
# try establishing a pubsub connection
await s.subscribePeer(muxer.connection.peerInfo)
except CancelledError as exc:
await muxer.close()
raise exc
except CatchableError as exc:
await muxer.close()
libp2p_failed_upgrade.inc()
trace "exception in muxer handler", exc = exc.msg
proc newSwitch*(peerInfo: PeerInfo,
transports: seq[Transport],
identity: Identify,
muxers: Table[string, MuxerProvider],
secureManagers: openarray[Secure] = [],
pubSub: Option[PubSub] = none(PubSub)): Switch =
if secureManagers.len == 0:
raise (ref CatchableError)(msg: "Provide at least one secure manager")
result = Switch(
peerInfo: peerInfo,
ms: newMultistream(),
transports: transports,
connections: initTable[string, seq[ConnectionHolder]](),
muxed: initTable[string, seq[MuxerHolder]](),
identity: identity,
muxers: muxers,
secureManagers: @secureManagers,
)
let s = result # can't capture result
result.streamHandler = proc(stream: Connection) {.async, gcsafe.} =
try:
trace "handling connection for", peerInfo = $stream
defer:
if not(isNil(stream)):
await stream.close()
await s.ms.handle(stream) # handle incoming connection
except CancelledError as exc:
raise exc
except CatchableError as exc:
trace "exception in stream handler", exc = exc.msg
result.mount(identity)
for key, val in muxers:
val.streamHandler = result.streamHandler
val.muxerHandler = proc(muxer: Muxer): Future[void] =
s.muxerHandler(muxer)
if pubSub.isSome:
result.pubSub = pubSub
result.mount(pubSub.get())