nim-libp2p/libp2p/switch.nim

437 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 std/[tables,
sequtils,
options,
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,
peerid,
errors
export connmanager, upgrade
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_total_dial_attempts, "total attempted dials")
declareCounter(libp2p_successful_dials, "dialed successful peers")
declareCounter(libp2p_failed_dials, "failed dials")
declareCounter(libp2p_failed_upgrades_incoming, "incoming connections failed upgrades")
declareCounter(libp2p_failed_upgrades_outgoing, "outgoing connections failed upgrades")
const
ConcurrentUpgrades* = 4
type
DialFailedError* = object of CatchableError
Switch* = ref object of RootObj
peerInfo*: PeerInfo
connManager*: ConnManager
transports*: seq[Transport]
ms*: MultistreamSelect
dialLock: Table[PeerID, AsyncLock]
acceptFuts: seq[Future[void]]
upgrade: Upgrade
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 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 disconnect*(s: Switch, peerId: PeerID): Future[void] {.gcsafe.} =
s.connManager.dropPeer(peerId)
proc dialAndUpgrade(s: Switch,
peerId: PeerID,
addrs: seq[MultiAddress]):
Future[Connection] {.async.} =
debug "Dialing peer", peerId
# Avoid "cannot be captured as it would violate memory safety" errors in Nim-1.4.x.
var
transport: Transport
address: MultiAddress
for t in s.transports: # for each transport
transport = t
for a in addrs: # for each address
address = a
if t.handles(a): # check if it can dial it
trace "Dialing address", address = $a, peerId
let dialed = try:
libp2p_total_dial_attempts.inc()
# await a connection slot when the total
# connection count is equal to `maxConns`
await s.connManager.trackOutgoingConn(
() => transport.dial(address)
)
except TooManyConnectionsError as exc:
trace "Connection limit reached!"
raise exc
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_successful_dials.inc()
let conn = try:
await s.upgrade.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_upgrades_outgoing.inc()
raise exc
doAssert not isNil(conn), "connection died after upgradeOutgoing"
debug "Dial successful", conn, peerInfo = conn.peerInfo
return conn
proc internalConnect(s: Switch,
peerId: PeerID,
addrs: seq[MultiAddress]):
Future[Connection] {.async.} =
if s.peerInfo.peerId == peerId:
raise newException(CatchableError, "can't dial self!")
# 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
var 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
conn = await s.dialAndUpgrade(peerId, addrs)
if isNil(conn): # None of the addresses connected
raise newException(DialFailedError, "Unable to establish outgoing link")
# We already check for this in Connection manager
# but a disconnect could have happened right after
# we've added the connection so we check again
# to prevent races due to that.
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
finally:
if lock.locked():
lock.release()
proc connect*(s: Switch, peerId: PeerID, addrs: seq[MultiAddress]) {.async.} =
## attempt to create establish a connection
## with a remote peer
##
if s.connManager.connCount(peerId) > 0:
return
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.getStream(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.} =
var
conn: Connection
stream: Connection
proc cleanup() {.async.} =
if not(isNil(stream)):
await stream.closeWithEOF()
if not(isNil(conn)):
await conn.close()
try:
trace "Dialing (new)", peerId, protos
conn = await s.internalConnect(peerId, addrs)
trace "Opening stream", conn
stream = await s.connManager.getStream(conn)
if isNil(stream):
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 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
debug "Accepted an incoming connection", conn
asyncSpawn upgradeMonitor(conn, upgrades)
asyncSpawn s.upgrade.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 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"
# 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 newSwitch*(peerInfo: PeerInfo,
transports: seq[Transport],
identity: Identify,
muxers: Table[string, MuxerProvider],
secureManagers: openarray[Secure] = [],
maxConnections = MaxConnections,
maxIn = -1,
maxOut = -1,
maxConnsPerPeer = MaxConnectionsPerPeer): Switch =
if secureManagers.len == 0:
raise (ref CatchableError)(msg: "Provide at least one secure manager")
let ms = newMultistream()
let connManager = ConnManager.init(maxConnsPerPeer, maxConnections, maxIn, maxOut)
let upgrade = MuxedUpgrade.init(identity, muxers, secureManagers, connManager, ms)
let switch = Switch(
peerInfo: peerInfo,
ms: ms,
transports: transports,
connManager: connManager,
upgrade: upgrade,
)
switch.mount(identity)
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)