nim-libp2p/libp2p/dialer.nim

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# Nim-LibP2P
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# Copyright (c) 2023 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.
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import std/[sugar, tables, sequtils]
import stew/results
import pkg/[chronos,
chronicles,
metrics]
import dial,
peerid,
peerinfo,
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multicodec,
multistream,
connmanager,
stream/connection,
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transports/transport,
nameresolving/nameresolver,
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upgrademngrs/upgrade,
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errors
export dial, errors, results
logScope:
topics = "libp2p dialer"
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_outgoing, "outgoing connections failed upgrades")
type
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DialFailedError* = object of LPError
Dialer* = ref object of Dial
localPeerId*: PeerId
ms: MultistreamSelect
connManager: ConnManager
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dialLock: Table[PeerId, AsyncLock]
transports: seq[Transport]
nameResolver: NameResolver
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proc dialAndUpgrade(
self: Dialer,
peerId: Opt[PeerId],
hostname: string,
address: MultiAddress):
Future[Connection] {.async.} =
for transport in self.transports: # for each transport
if transport.handles(address): # check if it can dial it
trace "Dialing address", address, peerId, hostname
let dialed =
try:
libp2p_total_dial_attempts.inc()
await transport.dial(hostname, address)
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()
return nil # Try the next address
# also keep track of the connection's bottom unsafe transport direction
# required by gossipsub scoring
dialed.transportDir = Direction.Out
libp2p_successful_dials.inc()
let conn =
try:
await transport.upgradeOutgoing(dialed, peerId)
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()
# Try other address
return nil
doAssert not isNil(conn), "connection died after upgradeOutgoing"
debug "Dial successful", conn, peerId = conn.peerId
return conn
return nil
proc expandDnsAddr(
self: Dialer,
peerId: Opt[PeerId],
address: MultiAddress): Future[seq[(MultiAddress, Opt[PeerId])]] {.async.} =
if not DNSADDR.matchPartial(address): return @[(address, peerId)]
if isNil(self.nameResolver):
info "Can't resolve DNSADDR without NameResolver", ma=address
return @[]
let
toResolve =
if peerId.isSome:
address & MultiAddress.init(multiCodec("p2p"), peerId.tryGet()).tryGet()
else:
address
resolved = await self.nameResolver.resolveDnsAddr(toResolve)
for resolvedAddress in resolved:
let lastPart = resolvedAddress[^1].tryGet()
if lastPart.protoCode == Result[MultiCodec, string].ok(multiCodec("p2p")):
let
peerIdBytes = lastPart.protoArgument().tryGet()
addrPeerId = PeerId.init(peerIdBytes).tryGet()
result.add((resolvedAddress[0..^2].tryGet(), Opt.some(addrPeerId)))
else:
result.add((resolvedAddress, peerId))
proc dialAndUpgrade(
self: Dialer,
peerId: Opt[PeerId],
addrs: seq[MultiAddress]):
Future[Connection] {.async.} =
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debug "Dialing peer", peerId
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for rawAddress in addrs:
# resolve potential dnsaddr
let addresses = await self.expandDnsAddr(peerId, rawAddress)
for (expandedAddress, addrPeerId) in addresses:
# DNS resolution
let
hostname = expandedAddress.getHostname()
resolvedAddresses =
if isNil(self.nameResolver): @[expandedAddress]
else: await self.nameResolver.resolveMAddress(expandedAddress)
for resolvedAddress in resolvedAddresses:
result = await self.dialAndUpgrade(addrPeerId, hostname, resolvedAddress)
if not isNil(result):
return result
proc internalConnect(
self: Dialer,
peerId: Opt[PeerId],
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addrs: seq[MultiAddress],
forceDial: bool):
Future[Connection] {.async.} =
if Opt.some(self.localPeerId) == peerId:
raise newException(CatchableError, "can't dial self!")
# Ensure there's only one in-flight attempt per peer
let lock = self.dialLock.mgetOrPut(peerId.get(default(PeerId)), newAsyncLock())
try:
await lock.acquire()
# Check if we have a connection already and try to reuse it
var conn =
if peerId.isSome: self.connManager.selectConn(peerId.get())
else: nil
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
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let slot = self.connManager.getOutgoingSlot(forceDial)
conn =
try:
await self.dialAndUpgrade(peerId, addrs)
except CatchableError as exc:
slot.release()
raise exc
slot.trackConnection(conn)
if isNil(conn): # None of the addresses connected
raise newException(DialFailedError, "Unable to establish outgoing link")
# 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()
method connect*(
self: Dialer,
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peerId: PeerId,
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addrs: seq[MultiAddress],
forceDial = false) {.async.} =
## connect remote peer without negotiating
## a protocol
##
if self.connManager.connCount(peerId) > 0:
return
discard await self.internalConnect(Opt.some(peerId), addrs, forceDial)
method connect*(
self: Dialer,
address: MultiAddress,
allowUnknownPeerId = false): Future[PeerId] {.async.} =
## Connects to a peer and retrieve its PeerId
let fullAddress = parseFullAddress(address)
if fullAddress.isOk:
return (await self.internalConnect(
Opt.some(fullAddress.get()[0]),
@[fullAddress.get()[1]],
false)).peerId
else:
if allowUnknownPeerId == false:
raise newException(DialFailedError, "Address without PeerID and unknown peer id disabled!")
return (await self.internalConnect(
Opt.none(PeerId),
@[address],
false)).peerId
proc negotiateStream(
self: Dialer,
conn: Connection,
protos: seq[string]): Future[Connection] {.async.} =
trace "Negotiating stream", conn, protos
let selected = await self.ms.select(conn, protos)
if not protos.contains(selected):
await conn.closeWithEOF()
raise newException(DialFailedError, "Unable to select sub-protocol " & $protos)
return conn
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method tryDial*(
self: Dialer,
peerId: PeerId,
addrs: seq[MultiAddress]): Future[Opt[MultiAddress]] {.async.} =
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## Create a protocol stream in order to check
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## if a connection is possible.
## Doesn't use the Connection Manager to save it.
##
trace "Check if it can dial", peerId, addrs
try:
let conn = await self.dialAndUpgrade(Opt.some(peerId), addrs)
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if conn.isNil():
raise newException(DialFailedError, "No valid multiaddress")
await conn.close()
return conn.observedAddr
except CancelledError as exc:
raise exc
except CatchableError as exc:
raise newException(DialFailedError, exc.msg)
method dial*(
self: Dialer,
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peerId: PeerId,
protos: seq[string]): Future[Connection] {.async.} =
## create a protocol stream over an
## existing connection
##
trace "Dialing (existing)", peerId, protos
let stream = await self.connManager.getStream(peerId)
if stream.isNil:
raise newException(DialFailedError, "Couldn't get muxed stream")
return await self.negotiateStream(stream, protos)
method dial*(
self: Dialer,
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peerId: PeerId,
addrs: seq[MultiAddress],
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protos: seq[string],
forceDial = false): Future[Connection] {.async.} =
## create a protocol stream and establish
## a connection if one doesn't exist already
##
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 self.internalConnect(Opt.some(peerId), addrs, forceDial)
trace "Opening stream", conn
stream = await self.connManager.getStream(conn)
if isNil(stream):
raise newException(DialFailedError,
"Couldn't get muxed stream")
return await self.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
method addTransport*(self: Dialer, t: Transport) =
self.transports &= t
proc new*(
T: type Dialer,
localPeerId: PeerId,
connManager: ConnManager,
transports: seq[Transport],
ms: MultistreamSelect,
nameResolver: NameResolver = nil): Dialer =
T(localPeerId: localPeerId,
connManager: connManager,
transports: transports,
ms: ms,
nameResolver: nameResolver)