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nim-libp2p-experimental
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nim-libp2p-experimental/libp2p/switch.nim

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## 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,
sets,
oids
import chronos,
chronicles,
metrics
import stream/connection,
transports/transport,
multistream,
multiaddress,
protocols/protocol,
protocols/secure/secure,
peerinfo,
protocols/identify,
muxers/muxer,
connmanager,
peerid,
errors
export connmanager
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)
declareCounter(libp2p_dialed_peers, "dialed peers")
declareCounter(libp2p_failed_dials, "failed dials")
declareCounter(libp2p_failed_upgrade, "peers failed upgrade")
type
UpgradeFailedError* = object of CatchableError
DialFailedError* = object of CatchableError
Switch* = ref object of RootObj
peerInfo*: PeerInfo
connManager: ConnManager
transports*: seq[Transport]
protocols*: seq[LPProtocol]
muxers*: Table[string, MuxerProvider]
ms*: MultistreamSelect
identity*: Identify
streamHandler*: StreamHandler
secureManagers*: seq[Secure]
dialLock: Table[PeerID, AsyncLock]
acceptFuts: seq[Future[void]]
proc addConnEventHandler*(s: Switch,
handler: ConnEventHandler,
kind: ConnEventKind) =
s.connManager.addConnEventHandler(handler, kind)
proc removeConnEventHandler*(s: Switch,
handler: ConnEventHandler,
kind: ConnEventKind) =
s.connManager.removeConnEventHandler(handler, kind)
proc addPeerEventHandler*(s: Switch,
handler: PeerEventHandler,
kind: PeerEvent) =
s.connManager.addPeerEventHandler(handler, kind)
proc removePeerEventHandler*(s: Switch,
handler: PeerEventHandler,
kind: PeerEvent) =
s.connManager.removePeerEventHandler(handler, kind)
proc disconnect*(s: Switch, peerId: PeerID) {.async, gcsafe.}
proc isConnected*(s: Switch, peerId: PeerID): bool =
## returns true if the peer has one or more
## associated connections (sockets)
##
peerId in s.connManager
proc secure(s: Switch, conn: Connection): Future[Connection] {.async, gcsafe.} =
if s.secureManagers.len <= 0:
raise newException(UpgradeFailedError, "No secure managers registered!")
let codec = await s.ms.select(conn, s.secureManagers.mapIt(it.codec))
if codec.len == 0:
raise newException(UpgradeFailedError, "Unable to negotiate a secure channel!")
trace "Securing connection", conn, codec
let secureProtocol = s.secureManagers.filterIt(it.codec == codec)
# 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)
return 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(UpgradeFailedError,
"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 "identified remote peer", conn, peerInfo = shortLog(conn.peerInfo)
proc identify(s: Switch, muxer: Muxer) {.async, gcsafe.} =
# new stream for identify
var stream = await muxer.newStream()
if stream == nil:
return
try:
await s.identify(stream)
finally:
await stream.closeWithEOF()
proc mux(s: Switch, conn: Connection): Future[Muxer] {.async, gcsafe.} =
## mux incoming connection
trace "Muxing connection", conn
if s.muxers.len == 0:
warn "no muxers registered, skipping upgrade flow", conn
return
let muxerName = await s.ms.select(conn, toSeq(s.muxers.keys()))
if muxerName.len == 0 or muxerName == "na":
debug "no muxer available, early exit", conn
return
trace "Found a muxer", conn, muxerName
# create new muxer for connection
let muxer = s.muxers[muxerName].newMuxer(conn)
# install stream handler
muxer.streamHandler = s.streamHandler
s.connManager.storeOutgoing(conn)
# store it in muxed connections if we have a peer for it
s.connManager.storeMuxer(muxer, muxer.handle()) # store muxer and start read loop
return muxer
proc disconnect*(s: Switch, peerId: PeerID): Future[void] {.gcsafe.} =
s.connManager.dropPeer(peerId)
proc upgradeOutgoing(s: Switch, conn: Connection): Future[Connection] {.async, gcsafe.} =
trace "Upgrading outgoing connection", conn
let sconn = await s.secure(conn) # secure the connection
if isNil(sconn):
raise newException(UpgradeFailedError,
"unable to secure connection, stopping upgrade")
if sconn.peerInfo.isNil:
raise newException(UpgradeFailedError,
"current version of nim-libp2p requires that secure protocol negotiates peerid")
let muxer = await s.mux(sconn) # mux it if possible
if muxer == nil:
# TODO this might be relaxed in the future
raise newException(UpgradeFailedError,
"a muxer is required for outgoing connections")
try:
await s.identify(muxer)
except CatchableError as exc:
# Identify is non-essential, though if it fails, it might indicate that
# the connection was closed already - this will be picked up by the read
# loop
debug "Could not identify connection", conn, msg = exc.msg
if isNil(sconn.peerInfo):
await sconn.close()
raise newException(UpgradeFailedError,
"No peerInfo for connection, stopping upgrade")
trace "Upgraded outgoing connection", conn, sconn
return sconn
proc upgradeIncoming(s: Switch, incomingConn: Connection) {.async, gcsafe.} = # noraises
trace "Upgrading incoming connection", incomingConn
let ms = newMultistream()
# secure incoming connections
proc securedHandler(conn: Connection,
proto: string)
{.async, gcsafe, closure.} =
trace "Starting secure handler", conn
let secure = s.secureManagers.filterIt(it.codec == proto)[0]
var sconn: Connection
try:
sconn = await secure.secure(conn, false)
if isNil(sconn):
return
# add the muxer
for muxer in s.muxers.values:
ms.addHandler(muxer.codecs, muxer)
# handle subsequent secure requests
await ms.handle(sconn)
except CatchableError as exc:
debug "Exception in secure handler during incoming upgrade", msg = exc.msg, conn
finally:
if not isNil(sconn):
await sconn.close()
trace "Stopped secure handler", conn
try:
if (await ms.select(incomingConn)): # just handshake
# add the secure handlers
for k in s.secureManagers:
ms.addHandler(k.codec, securedHandler)
# handle un-secured connections
# we handshaked above, set this ms handler as active
await ms.handle(incomingConn, active = true)
except CatchableError as exc:
debug "Exception upgrading incoming", exc = exc.msg
finally:
await incomingConn.close()
proc internalConnect(s: Switch,
peerId: PeerID,
addrs: seq[MultiAddress]): Future[Connection] {.async.} =
if s.peerInfo.peerId == peerId:
raise newException(CatchableError, "can't dial self!")
var conn: Connection
# Ensure there's only one in-flight attempt per peer
let lock = s.dialLock.mgetOrPut(peerId, newAsyncLock())
try:
await lock.acquire()
# Check if we have a connection already and try to reuse it
conn = s.connManager.selectConn(peerId)
if conn != nil:
if conn.atEof or conn.closed:
# This connection should already have been removed from the connection
# manager - it's essentially a bug that we end up here - we'll fail
# for now, hoping that this will clean themselves up later...
warn "dead connection in connection manager", conn
await conn.close()
raise newException(DialFailedError, "Zombie connection encountered")
trace "Reusing existing connection", conn, direction = $conn.dir
return conn
debug "Dialing peer", peerId
for t in s.transports: # for each transport
for a in addrs: # for each address
if t.handles(a): # check if it can dial it
trace "Dialing address", address = $a, peerId
let dialed = try:
await t.dial(a)
except CancelledError as exc:
debug "Dialing canceled", msg = exc.msg, peerId
raise exc
except CatchableError as exc:
debug "Dialing failed", msg = exc.msg, peerId
libp2p_failed_dials.inc()
continue # Try the next address
# make sure to assign the peer to the connection
dialed.peerInfo = PeerInfo.init(peerId, addrs)
libp2p_dialed_peers.inc()
let upgraded = try:
await s.upgradeOutgoing(dialed)
except CatchableError as exc:
# If we failed to establish the connection through one transport,
# we won't succeeded through another - no use in trying again
await dialed.close()
debug "Upgrade failed", msg = exc.msg, peerId
if exc isnot CancelledError:
libp2p_failed_upgrade.inc()
raise exc
doAssert not isNil(upgraded), "connection died after upgradeOutgoing"
conn = upgraded
debug "Dial successful", conn, peerInfo = conn.peerInfo
break
finally:
if lock.locked():
lock.release()
if isNil(conn): # None of the addresses connected
raise newException(DialFailedError, "Unable to establish outgoing link")
if conn.closed() or conn.atEof():
# This can happen when the other ends drops us
# before we get a chance to return the connection
# back to the dialer.
trace "Connection dead on arrival", conn
raise newLPStreamClosedError()
return conn
proc connect*(s: Switch, peerId: PeerID, addrs: seq[MultiAddress]) {.async.} =
discard await s.internalConnect(peerId, addrs)
proc negotiateStream(s: Switch, conn: Connection, protos: seq[string]): Future[Connection] {.async.} =
trace "Negotiating stream", conn, protos
let selected = await s.ms.select(conn, protos)
if not protos.contains(selected):
await conn.closeWithEOF()
raise newException(DialFailedError, "Unable to select sub-protocol " & $protos)
return conn
proc dial*(s: Switch,
peerId: PeerID,
protos: seq[string]): Future[Connection] {.async.} =
trace "Dialing (existing)", peerId, protos
let stream = await s.connManager.getMuxedStream(peerId)
if stream.isNil:
raise newException(DialFailedError, "Couldn't get muxed stream")
return await s.negotiateStream(stream, protos)
proc dial*(s: Switch,
peerId: PeerID,
proto: string): Future[Connection] = dial(s, peerId, @[proto])
proc dial*(s: Switch,
peerId: PeerID,
addrs: seq[MultiAddress],
protos: seq[string]):
Future[Connection] {.async.} =
trace "Dialing (new)", peerId, protos
let conn = await s.internalConnect(peerId, addrs)
trace "Opening stream", conn
let stream = await s.connManager.getMuxedStream(conn)
proc cleanup() {.async.} =
if not(isNil(stream)):
await stream.closeWithEOF()
if not(isNil(conn)):
await conn.close()
try:
if isNil(stream):
await conn.close()
raise newException(DialFailedError, "Couldn't get muxed stream")
return await s.negotiateStream(stream, protos)
except CancelledError as exc:
trace "Dial canceled", conn
await cleanup()
raise exc
except CatchableError as exc:
debug "Error dialing", conn, msg = exc.msg
await cleanup()
raise exc
proc dial*(s: Switch,
peerId: PeerID,
addrs: seq[MultiAddress],
proto: string):
Future[Connection] = dial(s, peerId, addrs, @[proto])
proc mount*[T: LPProtocol](s: Switch, proto: T, matcher: Matcher = nil) {.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.codecs, proto, matcher)
proc accept(s: Switch, transport: Transport) {.async.} = # noraises
## transport's accept loop
##
while transport.running:
var conn: Connection
try:
debug "About to accept incoming connection"
conn = await transport.accept()
if not isNil(conn):
debug "Accepted an incoming connection", conn
asyncSpawn s.upgradeIncoming(conn) # perform upgrade on incoming connection
else:
# A nil connection means that we might have hit a
# file-handle limit (or another non-fatal error),
# we can get one on the next try, but we should
# be careful to not end up in a thigh loop that
# will starve the main event loop, thus we sleep
# here before retrying.
await sleepAsync(100.millis) # TODO: should be configurable?
except CatchableError as exc:
debug "Exception in accept loop, exiting", exc = exc.msg
if not isNil(conn):
await conn.close()
return
proc start*(s: Switch): Future[seq[Future[void]]] {.async, gcsafe.} =
trace "starting switch for peer", peerInfo = s.peerInfo
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 = t.start(a)
s.peerInfo.addrs[i] = t.ma # update peer's address
s.acceptFuts.add(s.accept(t))
startFuts.add(server)
debug "Started libp2p node", peer = s.peerInfo
return startFuts # listen for incoming connections
proc stop*(s: Switch) {.async.} =
trace "Stopping switch"
for a in s.acceptFuts:
if not a.finished:
a.cancel()
checkFutures(
await allFinished(s.acceptFuts))
# close and cleanup all connections
await s.connManager.close()
for t in s.transports:
try:
await t.stop()
except CancelledError as exc:
raise exc
except CatchableError as exc:
warn "error cleaning up transports", msg = exc.msg
trace "Switch stopped"
proc muxerHandler(s: Switch, muxer: Muxer) {.async, gcsafe.} =
let
conn = muxer.connection
if conn.peerInfo.isNil:
warn "This version of nim-libp2p requires secure protocol to negotiate peerid"
await muxer.close()
return
# store incoming connection
s.connManager.storeIncoming(conn)
# store muxer and muxed connection
s.connManager.storeMuxer(muxer)
try:
await s.identify(muxer)
except IdentifyError as exc:
# Identify is non-essential, though if it fails, it might indicate that
# the connection was closed already - this will be picked up by the read
# loop
debug "Could not identify connection", conn, msg = exc.msg
except LPStreamClosedError as exc:
debug "Identify stream closed", conn, msg = exc.msg
except LPStreamEOFError as exc:
debug "Identify stream EOF", conn, msg = exc.msg
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", conn, msg = exc.msg
proc newSwitch*(peerInfo: PeerInfo,
transports: seq[Transport],
identity: Identify,
muxers: Table[string, MuxerProvider],
secureManagers: openarray[Secure] = []): Switch =
if secureManagers.len == 0:
raise (ref CatchableError)(msg: "Provide at least one secure manager")
let switch = Switch(
peerInfo: peerInfo,
ms: newMultistream(),
transports: transports,
connManager: ConnManager.init(),
identity: identity,
muxers: muxers,
secureManagers: @secureManagers,
)
switch.streamHandler = proc(conn: Connection) {.async, gcsafe.} = # noraises
trace "Starting stream handler", conn
try:
await switch.ms.handle(conn) # handle incoming connection
except CancelledError as exc:
raise exc
except CatchableError as exc:
trace "exception in stream handler", conn, msg = exc.msg
finally:
await conn.closeWithEOF()
trace "Stream handler done", conn
switch.mount(identity)
for key, val in muxers:
val.streamHandler = switch.streamHandler
val.muxerHandler = proc(muxer: Muxer): Future[void] =
switch.muxerHandler(muxer)
return switch
proc isConnected*(s: Switch, peerInfo: PeerInfo): bool
{.deprecated: "Use PeerID version".} =
not isNil(peerInfo) and isConnected(s, peerInfo.peerId)
proc disconnect*(s: Switch, peerInfo: PeerInfo): Future[void]
{.deprecated: "Use PeerID version", gcsafe.} =
disconnect(s, peerInfo.peerId)
proc connect*(s: Switch, peerInfo: PeerInfo): Future[void]
{.deprecated: "Use PeerID version".} =
connect(s, peerInfo.peerId, peerInfo.addrs)
proc dial*(s: Switch,
peerInfo: PeerInfo,
proto: string):
Future[Connection]
{.deprecated: "Use PeerID version".} =
dial(s, peerInfo.peerId, peerInfo.addrs, proto)
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