nim-libp2p/libp2p/switch.nim

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## Nim-LibP2P
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## Copyright (c) 2019 Status Research & Development GmbH
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## 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,
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transports/transport,
multistream,
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multiaddress,
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protocols/protocol,
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protocols/secure/secure,
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peerinfo,
protocols/identify,
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muxers/muxer,
connmanager,
peerid,
errors
chronicles.formatIt(PeerInfo): $it
chronicles.formatIt(PeerID): $it
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logScope:
topics = "switch"
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#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
NoPubSubException* = object of CatchableError
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ConnEventKind* {.pure.} = enum
Connected, # A connection was made and securely upgraded - there may be
# more than one concurrent connection thus more than one upgrade
# event per peer.
Disconnected # Peer disconnected - this event is fired once per upgrade
# when the associated connection is terminated.
ConnEvent* = object
case kind*: ConnEventKind
of ConnEventKind.Connected:
incoming*: bool
else:
discard
ConnEventHandler* =
proc(peerId: PeerID, event: ConnEvent): Future[void] {.gcsafe.}
Switch* = ref object of RootObj
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peerInfo*: PeerInfo
connManager: ConnManager
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transports*: seq[Transport]
protocols*: seq[LPProtocol]
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muxers*: Table[string, MuxerProvider]
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ms*: MultistreamSelect
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identity*: Identify
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streamHandler*: StreamHandler
secureManagers*: seq[Secure]
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dialLock: Table[PeerID, AsyncLock]
ConnEvents: Table[ConnEventKind, HashSet[ConnEventHandler]]
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proc addConnEventHandler*(s: Switch,
handler: ConnEventHandler, kind: ConnEventKind) =
## Add peer event handler - handlers must not raise exceptions!
if isNil(handler): return
s.ConnEvents.mgetOrPut(kind, initHashSet[ConnEventHandler]()).incl(handler)
proc removeConnEventHandler*(s: Switch,
handler: ConnEventHandler, kind: ConnEventKind) =
s.ConnEvents.withValue(kind, handlers) do:
handlers[].excl(handler)
proc triggerConnEvent(s: Switch, peerId: PeerID, event: ConnEvent) {.async, gcsafe.} =
try:
if event.kind in s.ConnEvents:
var ConnEvents: seq[Future[void]]
for h in s.ConnEvents[event.kind]:
ConnEvents.add(h(peerId, event))
checkFutures(await allFinished(ConnEvents))
except CancelledError as exc:
raise exc
except CatchableError as exc: # handlers should not raise!
warn "exception in trigger ConnEvents", exc = exc.msg
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:
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raise newException(CatchableError, "No secure managers registered!")
let manager = await s.ms.select(conn, s.secureManagers.mapIt(it.codec))
if manager.len == 0:
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raise newException(CatchableError, "Unable to negotiate a secure channel!")
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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
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doAssert(secureProtocol.len > 0)
result = await secureProtocol[0].secure(conn, true)
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proc identify(s: Switch, conn: Connection) {.async, gcsafe.} =
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## identify the connection
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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()
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if info.protoVersion.isSome:
conn.peerInfo.protoVersion = info.protoVersion.get()
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if info.protos.len > 0:
conn.peerInfo.protocols = info.protos
trace "identify: identified remote peer", peer = $conn.peerInfo
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proc identify(s: Switch, muxer: Muxer) {.async, gcsafe.} =
# new stream for identify
var stream = await muxer.newStream()
defer:
if not(isNil(stream)):
await stream.close() # close identify stream
# do identify first, so that we have a
# PeerInfo in case we didn't before
await s.identify(stream)
proc mux(s: Switch, conn: Connection): Future[Muxer] {.async, gcsafe.} =
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## mux incoming connection
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trace "muxing connection", peer = $conn
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if s.muxers.len == 0:
warn "no muxers registered, skipping upgrade flow"
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return
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let muxerName = await s.ms.select(conn, toSeq(s.muxers.keys()))
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if muxerName.len == 0 or muxerName == "na":
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debug "no muxer available, early exit", peer = $conn
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return
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# create new muxer for connection
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let muxer = s.muxers[muxerName].newMuxer(conn)
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# install stream handler
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muxer.streamHandler = s.streamHandler
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s.connManager.storeOutgoing(muxer.connection)
s.connManager.storeMuxer(muxer)
trace "found a muxer", name = muxerName, peer = $conn
# start muxer read loop - the future will complete when loop ends
let handlerFut = muxer.handle()
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# store it in muxed connections if we have a peer for it
trace "adding muxer for peer", peer = conn.peerInfo.id
s.connManager.storeMuxer(muxer, handlerFut) # update muxer with handler
return muxer
proc disconnect*(s: Switch, peerId: PeerID): Future[void] {.gcsafe.} =
s.connManager.dropPeer(peerId)
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proc upgradeOutgoing(s: Switch, conn: Connection): Future[Connection] {.async, gcsafe.} =
let sconn = await s.secure(conn) # secure the connection
if isNil(sconn):
raise newException(CatchableError,
"unable to secure connection, stopping upgrade")
if sconn.peerInfo.isNil:
raise newException(CatchableError,
"current version of nim-libp2p requires that secure protocol negotiates peerid")
trace "upgrading connection", conn = $sconn, uoid = $conn.oid
let muxer = await s.mux(sconn) # mux it if possible
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if muxer == nil:
# TODO this might be relaxed in the future
raise newException(CatchableError,
"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",
err = exc.msg, conn = $conn, uoid = $conn.oid
if isNil(sconn.peerInfo):
await sconn.close()
raise newException(CatchableError,
"unable to identify connection, stopping upgrade")
trace "successfully upgraded outgoing connection",
conn = $sconn, uoid = $conn.oid, oid = $sconn.oid
return sconn
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proc upgradeIncoming(s: Switch, conn: Connection) {.async, gcsafe.} =
trace "upgrading incoming connection", conn = $conn, oid = $conn.oid
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let ms = newMultistream()
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# 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()
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# add the muxer
for muxer in s.muxers.values:
ms.addHandler(muxer.codec, muxer)
# handle subsequent secure requests
await ms.handle(sconn)
except CancelledError as exc:
raise exc
except CatchableError as exc:
debug "ending secured handler",
err = exc.msg, conn = $conn, oid = $conn.oid
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if (await ms.select(conn)): # just handshake
# add the secure handlers
for k in s.secureManagers:
ms.addHandler(k.codec, securedHandler)
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# handle un-secured connections
# we handshaked above, set this ms handler as active
await ms.handle(conn, active = true)
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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
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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", peer = $peerId
await conn.close()
raise newException(CatchableError, "Zombie connection encountered")
trace "Reusing existing connection",
oid = $conn.oid, direction = $conn.dir, peer = $peerId
return conn
trace "Dialing peer"
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
let dialed = try:
await t.dial(a)
except CancelledError as exc:
trace "dialing canceled", exc = exc.msg, peer = $peerId
raise exc
except CatchableError as exc:
trace "dialing failed", exc = exc.msg, peer = $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 succeeed through another - no use in trying again
await dialed.close()
debug "upgrade failed", exc = exc.msg
if exc isnot CancelledError:
libp2p_failed_upgrade.inc()
raise exc
doAssert not isNil(upgraded), "connection died after upgradeOutgoing"
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conn = upgraded
trace "dial successful",
peer = $peerId,
oid = $upgraded.oid,
peerInfo = shortLog(upgraded.peerInfo)
break
finally:
if lock.locked():
lock.release()
if isNil(conn): # None of the addresses connected
raise newException(CatchableError, "Unable to establish outgoing link")
if conn.closed():
# This can happen if one of the peer event handlers deems the peer
# unworthy and disconnects it
raise newLPStreamClosedError()
await s.triggerConnEvent(
peerId, ConnEvent(kind: ConnEventKind.Connected, incoming: false))
proc peerCleanup() {.async.} =
try:
await conn.closeEvent.wait()
await s.triggerConnEvent(peerId,
ConnEvent(kind: ConnEventKind.Disconnected))
except CancelledError:
# This is top-level procedure which will work as separate task, so it
# do not need to propogate CancelledError.
trace "Unexpected cancellation in switch peer connect cleanup",
peer = $peerId
except CatchableError as exc:
trace "Unexpected exception in switch peer connect cleanup",
errMsg = exc.msg, peer = $peerId
# All the errors are handled inside `cleanup()` procedure.
asyncSpawn peerCleanup()
return conn
proc connect*(s: Switch, peerId: PeerID, addrs: seq[MultiAddress]) {.async.} =
discard await s.internalConnect(peerId, addrs)
proc negotiateStream(s: Switch, stream: Connection, proto: string): Future[Connection] {.async.} =
trace "Attempting to select remote", proto = proto,
streamOid = $stream.oid,
oid = $stream.oid
if not await s.ms.select(stream, proto):
await stream.close()
raise newException(CatchableError, "Unable to select sub-protocol" & proto)
return stream
proc dial*(s: Switch,
peerId: PeerID,
proto: string): Future[Connection] {.async.} =
let stream = await s.connmanager.getMuxedStream(peerId)
if stream.isNil:
raise newException(CatchableError, "Couldn't get muxed stream")
return await s.negotiateStream(stream, proto)
proc dial*(s: Switch,
peerId: PeerID,
addrs: seq[MultiAddress],
proto: string):
Future[Connection] {.async.} =
let conn = await s.internalConnect(peerId, addrs)
let stream = await s.connManager.getMuxedStream(conn)
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")
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return await s.negotiateStream(stream, proto)
except CancelledError as exc:
trace "dial canceled"
await cleanup()
raise exc
except CatchableError as exc:
trace "error dialing", exc = exc.msg
await cleanup()
raise exc
proc mount*[T: LPProtocol](s: Switch, proto: T) {.gcsafe.} =
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if isNil(proto.handler):
raise newException(CatchableError,
"Protocol has to define a handle method or proc")
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if proto.codec.len == 0:
raise newException(CatchableError,
"Protocol has to define a codec string")
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s.ms.addHandler(proto.codec, proto)
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proc start*(s: Switch): Future[seq[Future[void]]] {.async, gcsafe.} =
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trace "starting switch for peer", peerInfo = shortLog(s.peerInfo)
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proc handle(conn: Connection): Future[void] {.async, closure, gcsafe.} =
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try:
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
finally:
await conn.close()
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var startFuts: seq[Future[void]]
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for t in s.transports: # for each transport
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for i, a in s.peerInfo.addrs:
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if t.handles(a): # check if it handles the multiaddr
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var server = await t.listen(a, handle)
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s.peerInfo.addrs[i] = t.ma # update peer's address
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startFuts.add(server)
debug "started libp2p node", peer = $s.peerInfo, addrs = s.peerInfo.addrs
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result = startFuts # listen for incoming connections
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proc stop*(s: Switch) {.async.} =
trace "stopping switch"
# close and cleanup all connections
await s.connManager.close()
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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 muxerHandler(s: Switch, muxer: Muxer) {.async, gcsafe.} =
if muxer.connection.peerInfo.isNil:
warn "This version of nim-libp2p requires secure protocol to negotiate peerid"
await muxer.close()
return
# store incoming connection
s.connManager.storeIncoming(muxer.connection)
# store muxer and muxed connection
s.connManager.storeMuxer(muxer)
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", err = exc.msg
try:
let peerId = muxer.connection.peerInfo.peerId
proc peerCleanup() {.async.} =
try:
await muxer.connection.closeEvent.wait()
await s.triggerConnEvent(peerId,
ConnEvent(kind: ConnEventKind.Disconnected))
except CancelledError:
# This is top-level procedure which will work as separate task, so it
# do not need to propogate CancelledError.
debug "Unexpected cancellation in switch muxer cleanup"
except CatchableError as exc:
debug "Unexpected exception in switch muxer cleanup",
errMsg = exc.msg
proc peerStartup() {.async.} =
try:
await s.triggerConnEvent(peerId,
ConnEvent(kind: ConnEventKind.Connected,
incoming: true))
except CancelledError:
# This is top-level procedure which will work as separate task, so it
# do not need to propogate CancelledError.
debug "Unexpected cancellation in switch muxer startup"
except CatchableError as exc:
debug "Unexpected exception in switch muxer startup",
errMsg = exc.msg
# All the errors are handled inside `peerStartup()` procedure.
asyncSpawn peerStartup()
# All the errors are handled inside `peerCleanup()` procedure.
asyncSpawn peerCleanup()
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
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proc newSwitch*(peerInfo: PeerInfo,
transports: seq[Transport],
identity: Identify,
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muxers: Table[string, MuxerProvider],
secureManagers: openarray[Secure] = []): Switch =
if secureManagers.len == 0:
raise (ref CatchableError)(msg: "Provide at least one secure manager")
result = Switch(
peerInfo: peerInfo,
ms: newMultistream(),
transports: transports,
connManager: ConnManager.init(),
identity: identity,
muxers: muxers,
secureManagers: @secureManagers,
)
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let s = result # can't capture result
result.streamHandler = proc(stream: Connection) {.async, gcsafe.} =
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try:
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trace "handling connection for", peerInfo = $stream
defer:
if not(isNil(stream)):
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await stream.close()
await s.ms.handle(stream) # handle incoming connection
except CancelledError as exc:
raise exc
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except CatchableError as exc:
trace "exception in stream handler", exc = exc.msg
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result.mount(identity)
for key, val in muxers:
val.streamHandler = result.streamHandler
val.muxerHandler = proc(muxer: Muxer): Future[void] =
s.muxerHandler(muxer)
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)