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nim-libp2p/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.
{.push raises: [Defect].}
import std/[tables,
options,
sequtils,
sets,
oids,
sugar,
math]
import chronos,
chronicles,
metrics
import stream/connection,
transports/transport,
upgrademngrs/[upgrade, muxedupgrade],
multistream,
multiaddress,
protocols/protocol,
protocols/secure/secure,
peerinfo,
protocols/identify,
muxers/muxer,
utils/semaphore,
connmanager,
nameresolving/nameresolver,
peerid,
peerstore,
errors,
dialer
export connmanager, upgrade, dialer, peerstore
logScope:
topics = "libp2p 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_failed_upgrades_incoming, "incoming connections failed upgrades")
const
ConcurrentUpgrades* = 4
type
Switch* = ref object of Dial
peerInfo*: PeerInfo
connManager*: ConnManager
transports*: seq[Transport]
ms*: MultistreamSelect
acceptFuts: seq[Future[void]]
dialer*: Dial
peerStore*: PeerStore
nameResolver*: NameResolver
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: PeerEventKind) =
s.connManager.addPeerEventHandler(handler, kind)
proc removePeerEventHandler*(s: Switch,
handler: PeerEventHandler,
kind: PeerEventKind) =
s.connManager.removePeerEventHandler(handler, kind)
proc isConnected*(s: Switch, peerId: PeerID): bool =
## returns true if the peer has one or more
## associated connections (sockets)
##
peerId in s.connManager
proc disconnect*(s: Switch, peerId: PeerID): Future[void] {.gcsafe.} =
s.connManager.dropPeer(peerId)
method connect*(
s: Switch,
peerId: PeerID,
addrs: seq[MultiAddress]): Future[void] =
s.dialer.connect(peerId, addrs)
method dial*(
s: Switch,
peerId: PeerID,
protos: seq[string]): Future[Connection] =
s.dialer.dial(peerId, protos)
proc dial*(s: Switch,
peerId: PeerID,
proto: string): Future[Connection] =
dial(s, peerId, @[proto])
method dial*(
s: Switch,
peerId: PeerID,
addrs: seq[MultiAddress],
protos: seq[string]): Future[Connection] =
s.dialer.dial(peerId, addrs, protos)
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, raises: [Defect, LPError].} =
if isNil(proto.handler):
raise newException(LPError,
"Protocol has to define a handle method or proc")
if proto.codec.len == 0:
raise newException(LPError,
"Protocol has to define a codec string")
s.ms.addHandler(proto.codecs, proto, matcher)
s.peerInfo.protocols.add(proto.codec)
proc upgradeMonitor(conn: Connection, upgrades: AsyncSemaphore) {.async.} =
## monitor connection for upgrades
##
try:
# Since we don't control the flow of the
# upgrade, this timeout guarantees that a
# "hanged" remote doesn't hold the upgrade
# forever
await conn.onUpgrade.wait(30.seconds) # wait for connection to be upgraded
trace "Connection upgrade succeeded"
except CatchableError as exc:
libp2p_failed_upgrades_incoming.inc()
if not isNil(conn):
await conn.close()
trace "Exception awaiting connection upgrade", exc = exc.msg, conn
finally:
upgrades.release() # don't forget to release the slot!
proc accept(s: Switch, transport: Transport) {.async.} = # noraises
## switch accept loop, ran for every transport
##
let upgrades = newAsyncSemaphore(ConcurrentUpgrades)
while transport.running:
var conn: Connection
try:
debug "About to accept incoming connection"
# remember to always release the slot when
# the upgrade succeeds or fails, this is
# currently done by the `upgradeMonitor`
await upgrades.acquire() # first wait for an upgrade slot to become available
conn = await s.connManager # next attempt to get an incoming connection
.trackIncomingConn(
() => transport.accept()
)
if isNil(conn):
# 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.
trace "Unable to get a connection, sleeping"
await sleepAsync(100.millis) # TODO: should be configurable?
upgrades.release()
continue
# set the direction of this bottom level transport
# in order to be able to consume this information in gossipsub if required
# gossipsub gives priority to connections we make
conn.transportDir = Direction.In
debug "Accepted an incoming connection", conn
asyncSpawn upgradeMonitor(conn, upgrades)
asyncSpawn transport.upgradeIncoming(conn)
except CancelledError as exc:
trace "releasing semaphore on cancellation"
upgrades.release() # always release the slot
except CatchableError as exc:
debug "Exception in accept loop, exiting", exc = exc.msg
upgrades.release() # always release the slot
if not isNil(conn):
await conn.close()
return
proc stop*(s: Switch) {.async.} =
trace "Stopping switch"
# 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
try:
await allFutures(s.acceptFuts)
.wait(1.seconds)
except CatchableError as exc:
trace "Exception while stopping accept loops", exc = exc.msg
# check that all futures were properly
# stopped and otherwise cancel them
for a in s.acceptFuts:
if not a.finished:
a.cancel()
trace "Switch stopped"
proc start*(s: Switch) {.async, gcsafe.} =
trace "starting switch for peer", peerInfo = s.peerInfo
var startFuts: seq[Future[void]]
for t in s.transports:
let addrs = s.peerInfo.addrs.filterIt(
t.handles(it)
)
s.peerInfo.addrs.keepItIf(
it notin addrs
)
if addrs.len > 0:
startFuts.add(t.start(addrs))
await allFutures(startFuts)
for s in startFuts:
if s.failed:
# TODO: replace this exception with a `listenError` callback. See
# https://github.com/status-im/nim-libp2p/pull/662 for more info.
raise newException(transport.TransportError,
"Failed to start one transport", s.error)
for t in s.transports: # for each transport
if t.addrs.len > 0:
s.acceptFuts.add(s.accept(t))
s.peerInfo.addrs &= t.addrs
debug "Started libp2p node", peer = s.peerInfo
proc newSwitch*(peerInfo: PeerInfo,
transports: seq[Transport],
identity: Identify,
muxers: Table[string, MuxerProvider],
secureManagers: openarray[Secure] = [],
connManager: ConnManager,
ms: MultistreamSelect,
nameResolver: NameResolver = nil): Switch
{.raises: [Defect, LPError].} =
if secureManagers.len == 0:
raise newException(LPError, "Provide at least one secure manager")
let switch = Switch(
peerInfo: peerInfo,
ms: ms,
transports: transports,
connManager: connManager,
peerStore: PeerStore.new(),
dialer: Dialer.new(peerInfo.peerId, connManager, transports, ms, nameResolver),
nameResolver: nameResolver)
switch.connManager.peerStore = switch.peerStore
switch.mount(identity)
return switch
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