nim-libp2p/libp2p/muxers/yamux/yamux.nim

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# Nim-LibP2P
# Copyright (c) 2023 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: [].}
import sequtils, std/[tables]
import chronos, chronicles, metrics, stew/[endians2, byteutils, objects]
import ../muxer,
../../stream/connection
export muxer
logScope:
topics = "libp2p yamux"
const
YamuxCodec* = "/yamux/1.0.0"
YamuxVersion = 0.uint8
YamuxDefaultWindowSize* = 256000
MaxSendQueueSize = 256000
MaxChannelCount = 200
when defined(libp2p_yamux_metrics):
declareGauge(libp2p_yamux_channels, "yamux channels", labels = ["initiator", "peer"])
declareHistogram libp2p_yamux_send_queue, "message send queue length (in byte)",
buckets = [0.0, 100.0, 250.0, 1000.0, 2000.0, 3200.0, 6400.0, 25600.0, 256000.0]
declareHistogram libp2p_yamux_recv_queue, "message recv queue length (in byte)",
buckets = [0.0, 100.0, 250.0, 1000.0, 2000.0, 3200.0, 6400.0, 25600.0, 256000.0]
type
YamuxError* = object of CatchableError
MsgType = enum
Data = 0x0
WindowUpdate = 0x1
Ping = 0x2
GoAway = 0x3
MsgFlags {.size: 2.} = enum
Syn
Ack
Fin
Rst
GoAwayStatus = enum
NormalTermination = 0x0,
ProtocolError = 0x1,
InternalError = 0x2,
YamuxHeader = object
version: uint8
msgType: MsgType
flags: set[MsgFlags]
streamId: uint32
length: uint32
proc readHeader(conn: LPStream): Future[YamuxHeader] {.async.} =
var buffer: array[12, byte]
await conn.readExactly(addr buffer[0], 12)
result.version = buffer[0]
let flags = fromBytesBE(uint16, buffer[2..3])
if not result.msgType.checkedEnumAssign(buffer[1]) or flags notin 0'u16..15'u16:
raise newException(YamuxError, "Wrong header")
result.flags = cast[set[MsgFlags]](flags)
result.streamId = fromBytesBE(uint32, buffer[4..7])
result.length = fromBytesBE(uint32, buffer[8..11])
return result
proc `$`(header: YamuxHeader): string =
result = "{" & $header.msgType & ", "
result &= "{" & header.flags.foldl(if a != "": a & ", " & $b else: $b, "") & "}, "
result &= "streamId: " & $header.streamId & ", "
result &= "length: " & $header.length & "}"
proc encode(header: YamuxHeader): array[12, byte] =
result[0] = header.version
result[1] = uint8(header.msgType)
result[2..3] = toBytesBE(uint16(cast[uint8](header.flags))) # workaround https://github.com/nim-lang/Nim/issues/21789
result[4..7] = toBytesBE(header.streamId)
result[8..11] = toBytesBE(header.length)
proc write(conn: LPStream, header: YamuxHeader): Future[void] {.gcsafe.} =
trace "write directly on stream", h = $header
var buffer = header.encode()
return conn.write(@buffer)
proc ping(T: type[YamuxHeader], flag: MsgFlags, pingData: uint32): T =
T(
version: YamuxVersion,
msgType: MsgType.Ping,
flags: {flag},
length: pingData
)
proc goAway(T: type[YamuxHeader], status: GoAwayStatus): T =
T(
version: YamuxVersion,
msgType: MsgType.GoAway,
length: uint32(status)
)
proc data(
T: type[YamuxHeader],
streamId: uint32,
length: uint32 = 0,
flags: set[MsgFlags] = {},
): T =
T(
version: YamuxVersion,
msgType: MsgType.Data,
length: length,
flags: flags,
streamId: streamId
)
proc windowUpdate(
T: type[YamuxHeader],
streamId: uint32,
delta: uint32,
flags: set[MsgFlags] = {},
): T =
T(
version: YamuxVersion,
msgType: MsgType.WindowUpdate,
length: delta,
flags: flags,
streamId: streamId
)
type
ToSend = tuple
data: seq[byte]
sent: int
fut: Future[void]
YamuxChannel* = ref object of Connection
id: uint32
recvWindow: int
sendWindow: int
maxRecvWindow: int
maxSendQueueSize: int
conn: Connection
isSrc: bool
opened: bool
isSending: bool
sendQueue: seq[ToSend]
recvQueue: seq[byte]
isReset: bool
remoteReset: bool
closedRemotely: Future[void]
closedLocally: bool
receivedData: AsyncEvent
returnedEof: bool
proc `$`(channel: YamuxChannel): string =
result = if channel.conn.dir == Out: "=> " else: "<= "
result &= $channel.id
var s: seq[string] = @[]
if channel.closedRemotely.done():
s.add("ClosedRemotely")
if channel.closedLocally:
s.add("ClosedLocally")
if channel.isReset:
s.add("Reset")
if s.len > 0:
result &= " {" & s.foldl(if a != "": a & ", " & b else: b, "") & "}"
proc lengthSendQueue(channel: YamuxChannel): int =
## Returns the length of what remains to be sent
##
channel.sendQueue.foldl(a + b.data.len - b.sent, 0)
proc lengthSendQueueWithLimit(channel: YamuxChannel): int =
## Returns the length of what remains to be sent, but limit the size of big messages.
##
# For leniency, limit big messages size to the third of maxSendQueueSize
# This value is arbitrary, it's not in the specs, it permits to store up to
# 3 big messages if the peer is stalling.
channel.sendQueue.foldl(a + min(b.data.len - b.sent, channel.maxSendQueueSize div 3), 0)
proc actuallyClose(channel: YamuxChannel) {.async.} =
if channel.closedLocally and channel.sendQueue.len == 0 and
channel.closedRemotely.done():
await procCall Connection(channel).closeImpl()
proc remoteClosed(channel: YamuxChannel) {.async.} =
if not channel.closedRemotely.done():
channel.closedRemotely.complete()
await channel.actuallyClose()
method closeImpl*(channel: YamuxChannel) {.async.} =
if not channel.closedLocally:
channel.closedLocally = true
channel.isEof = true
if not channel.isReset and channel.sendQueue.len == 0:
try: await channel.conn.write(YamuxHeader.data(channel.id, 0, {Fin}))
except CancelledError, LPStreamError: discard
await channel.actuallyClose()
proc reset(channel: YamuxChannel, isLocal: bool = false) {.async.} =
# If we reset locally, we want to flush up to a maximum of recvWindow
# bytes. It's because the peer we're connected to can send us data before
# it receives the reset.
if channel.isReset:
return
trace "Reset channel"
channel.isReset = true
channel.remoteReset = not isLocal
for (d, s, fut) in channel.sendQueue:
fut.fail(newLPStreamEOFError())
channel.sendQueue = @[]
channel.recvQueue = @[]
channel.sendWindow = 0
if not channel.closedLocally:
if isLocal and not channel.isSending:
try: await channel.conn.write(YamuxHeader.data(channel.id, 0, {Rst}))
except LPStreamEOFError as exc: discard
except LPStreamClosedError as exc: discard
await channel.close()
if not channel.closedRemotely.done():
await channel.remoteClosed()
channel.receivedData.fire()
if not isLocal:
# If the reset is remote, there's no reason to flush anything.
channel.recvWindow = 0
proc updateRecvWindow(channel: YamuxChannel) {.async.} =
## Send to the peer a window update when the recvWindow is empty enough
##
# In order to avoid spamming a window update everytime a byte is read,
# we send it everytime half of the maxRecvWindow is read.
let inWindow = channel.recvWindow + channel.recvQueue.len
if inWindow > channel.maxRecvWindow div 2:
return
let delta = channel.maxRecvWindow - inWindow
channel.recvWindow.inc(delta)
await channel.conn.write(YamuxHeader.windowUpdate(
channel.id,
delta.uint32
))
trace "increasing the recvWindow", delta
method readOnce*(
channel: YamuxChannel,
pbytes: pointer,
nbytes: int):
Future[int] {.async.} =
## Read from a yamux channel
if channel.isReset:
raise if channel.remoteReset:
newLPStreamResetError()
elif channel.closedLocally:
newLPStreamClosedError()
else:
newLPStreamConnDownError()
if channel.returnedEof:
raise newLPStreamRemoteClosedError()
if channel.recvQueue.len == 0:
channel.receivedData.clear()
try: # https://github.com/status-im/nim-chronos/issues/516
discard await race(channel.closedRemotely, channel.receivedData.wait())
except ValueError: raiseAssert("Futures list is not empty")
if channel.closedRemotely.done() and channel.recvQueue.len == 0:
channel.returnedEof = true
channel.isEof = true
return 0
let toRead = min(channel.recvQueue.len, nbytes)
var p = cast[ptr UncheckedArray[byte]](pbytes)
toOpenArray(p, 0, nbytes - 1)[0..<toRead] = channel.recvQueue.toOpenArray(0, toRead - 1)
channel.recvQueue = channel.recvQueue[toRead..^1]
# We made some room in the recv buffer let the peer know
await channel.updateRecvWindow()
channel.activity = true
return toRead
proc gotDataFromRemote(channel: YamuxChannel, b: seq[byte]) {.async.} =
channel.recvWindow -= b.len
channel.recvQueue = channel.recvQueue.concat(b)
channel.receivedData.fire()
when defined(libp2p_yamux_metrics):
libp2p_yamux_recv_queue.observe(channel.recvQueue.len.int64)
await channel.updateRecvWindow()
proc setMaxRecvWindow*(channel: YamuxChannel, maxRecvWindow: int) =
channel.maxRecvWindow = maxRecvWindow
proc trySend(channel: YamuxChannel) {.async.} =
if channel.isSending:
return
channel.isSending = true
defer: channel.isSending = false
while channel.sendQueue.len != 0:
channel.sendQueue.keepItIf(not (it.fut.cancelled() and it.sent == 0))
if channel.sendWindow == 0:
trace "trying to send while the sendWindow is empty"
if channel.lengthSendQueueWithLimit() > channel.maxSendQueueSize:
trace "channel send queue too big, resetting", maxSendQueueSize=channel.maxSendQueueSize,
currentQueueSize = channel.lengthSendQueueWithLimit()
try:
await channel.reset(true)
except CatchableError as exc:
warn "failed to reset", msg=exc.msg
break
let
bytesAvailable = channel.lengthSendQueue()
toSend = min(channel.sendWindow, bytesAvailable)
var
sendBuffer = newSeqUninitialized[byte](toSend + 12)
header = YamuxHeader.data(channel.id, toSend.uint32)
inBuffer = 0
if toSend >= bytesAvailable and channel.closedLocally:
trace "last buffer we'll sent on this channel", toSend, bytesAvailable
header.flags.incl({Fin})
sendBuffer[0..<12] = header.encode()
var futures: seq[Future[void]]
while inBuffer < toSend:
# concatenate the different message we try to send into one buffer
let (data, sent, fut) = channel.sendQueue[0]
let bufferToSend = min(data.len - sent, toSend - inBuffer)
sendBuffer.toOpenArray(12, 12 + toSend - 1)[inBuffer..<(inBuffer+bufferToSend)] =
channel.sendQueue[0].data.toOpenArray(sent, sent + bufferToSend - 1)
channel.sendQueue[0].sent.inc(bufferToSend)
if channel.sendQueue[0].sent >= data.len:
# if every byte of the message is in the buffer, add the write future to the
# sequence of futures to be completed (or failed) when the buffer is sent
futures.add(fut)
channel.sendQueue.delete(0)
inBuffer.inc(bufferToSend)
trace "try to send the buffer", h = $header
channel.sendWindow.dec(toSend)
try: await channel.conn.write(sendBuffer)
except CatchableError as exc:
trace "failed to send the buffer"
let connDown = newLPStreamConnDownError(exc)
for fut in futures.items():
fut.fail(connDown)
await channel.reset()
break
for fut in futures.items():
fut.complete()
channel.activity = true
method write*(channel: YamuxChannel, msg: seq[byte]): Future[void] =
## Write to yamux channel
##
result = newFuture[void]("Yamux Send")
if channel.remoteReset:
result.fail(newLPStreamResetError())
return result
if channel.closedLocally or channel.isReset:
result.fail(newLPStreamClosedError())
return result
if msg.len == 0:
result.complete()
return result
channel.sendQueue.add((msg, 0, result))
when defined(libp2p_yamux_metrics):
libp2p_yamux_send_queue.observe(channel.lengthSendQueue().int64)
asyncSpawn channel.trySend()
proc open(channel: YamuxChannel) {.async.} =
## Open a yamux channel by sending a window update with Syn or Ack flag
##
if channel.opened:
trace "Try to open channel twice"
return
channel.opened = true
await channel.conn.write(YamuxHeader.windowUpdate(
channel.id,
uint32(max(channel.maxRecvWindow - YamuxDefaultWindowSize, 0)),
{if channel.isSrc: Syn else: Ack}))
method getWrapped*(channel: YamuxChannel): Connection = channel.conn
type
Yamux* = ref object of Muxer
channels: Table[uint32, YamuxChannel]
flushed: Table[uint32, int]
currentId: uint32
isClosed: bool
maxChannCount: int
windowSize: int
maxSendQueueSize: int
inTimeout: Duration
outTimeout: Duration
proc lenBySrc(m: Yamux, isSrc: bool): int =
for v in m.channels.values():
if v.isSrc == isSrc: result += 1
proc cleanupChannel(m: Yamux, channel: YamuxChannel) {.async.} =
await channel.join()
m.channels.del(channel.id)
when defined(libp2p_yamux_metrics):
libp2p_yamux_channels.set(m.lenBySrc(channel.isSrc).int64, [$channel.isSrc, $channel.peerId])
if channel.isReset and channel.recvWindow > 0:
m.flushed[channel.id] = channel.recvWindow
proc createStream(m: Yamux, id: uint32, isSrc: bool,
recvWindow: int, maxSendQueueSize: int): YamuxChannel =
# As you can see, during initialization, recvWindow can be larger than maxRecvWindow.
# This is because the peer we're connected to will always assume
# that the initial recvWindow is 256k.
# To solve this contradiction, no updateWindow will be sent until recvWindow is less
# than maxRecvWindow
var stream = YamuxChannel(
id: id,
maxRecvWindow: recvWindow,
recvWindow: if recvWindow > YamuxDefaultWindowSize: recvWindow else: YamuxDefaultWindowSize,
sendWindow: YamuxDefaultWindowSize,
maxSendQueueSize: maxSendQueueSize,
isSrc: isSrc,
conn: m.connection,
receivedData: newAsyncEvent(),
closedRemotely: newFuture[void]()
)
stream.objName = "YamuxStream"
if isSrc:
stream.dir = Direction.Out
stream.timeout = m.outTimeout
else:
stream.dir = Direction.In
stream.timeout = m.inTimeout
stream.timeoutHandler = proc(): Future[void] {.gcsafe.} =
trace "Idle timeout expired, resetting YamuxChannel"
stream.reset(true)
stream.initStream()
stream.peerId = m.connection.peerId
stream.observedAddr = m.connection.observedAddr
stream.transportDir = m.connection.transportDir
when defined(libp2p_agents_metrics):
stream.shortAgent = m.connection.shortAgent
m.channels[id] = stream
asyncSpawn m.cleanupChannel(stream)
trace "created channel", id, pid=m.connection.peerId
when defined(libp2p_yamux_metrics):
libp2p_yamux_channels.set(m.lenBySrc(isSrc).int64, [$isSrc, $stream.peerId])
return stream
method close*(m: Yamux) {.async.} =
if m.isClosed == true:
trace "Already closed"
return
m.isClosed = true
trace "Closing yamux"
let channels = toSeq(m.channels.values())
for channel in channels:
await channel.reset(true)
try: await m.connection.write(YamuxHeader.goAway(NormalTermination))
except CatchableError as exc: trace "failed to send goAway", msg=exc.msg
await m.connection.close()
trace "Closed yamux"
proc handleStream(m: Yamux, channel: YamuxChannel) {.async.} =
## Call the muxer stream handler for this channel
##
try:
await m.streamHandler(channel)
trace "finished handling stream"
doAssert(channel.isClosed, "connection not closed by handler!")
except CatchableError as exc:
trace "Exception in yamux stream handler", msg = exc.msg
await channel.reset()
method handle*(m: Yamux) {.async.} =
trace "Starting yamux handler", pid=m.connection.peerId
try:
while not m.connection.atEof:
trace "waiting for header"
let header = await m.connection.readHeader()
trace "got message", h = $header
case header.msgType:
of Ping:
if MsgFlags.Syn in header.flags:
await m.connection.write(YamuxHeader.ping(MsgFlags.Ack, header.length))
of GoAway:
var status: GoAwayStatus
if status.checkedEnumAssign(header.length): trace "Received go away", status
else: trace "Received unexpected error go away"
break
of Data, WindowUpdate:
if MsgFlags.Syn in header.flags:
if header.streamId in m.channels:
debug "Trying to create an existing channel, skipping", id=header.streamId
else:
if header.streamId in m.flushed:
m.flushed.del(header.streamId)
if header.streamId mod 2 == m.currentId mod 2:
debug "Peer used our reserved stream id, skipping", id=header.streamId, currentId=m.currentId, peerId=m.connection.peerId
raise newException(YamuxError, "Peer used our reserved stream id")
let newStream = m.createStream(header.streamId, false, m.windowSize, m.maxSendQueueSize)
if m.channels.len >= m.maxChannCount:
await newStream.reset()
continue
await newStream.open()
asyncSpawn m.handleStream(newStream)
elif header.streamId notin m.channels:
# Flush the data
m.flushed.withValue(header.streamId, flushed):
if header.msgType == Data:
flushed[].dec(int(header.length))
if flushed[] < 0:
raise newException(YamuxError,
"Peer exhausted the recvWindow after reset")
do:
raise newException(YamuxError,
"Unknown stream ID: " & $header.streamId)
if header.length > 0:
var buffer = newSeqUninitialized[byte](header.length)
await m.connection.readExactly(
addr buffer[0], int(header.length))
continue
let channel =
try:
m.channels[header.streamId]
except KeyError:
raise newException(YamuxError,
"Stream was cleaned up before handling data: " & $header.streamId)
if header.msgType == WindowUpdate:
channel.sendWindow += int(header.length)
await channel.trySend()
else:
if header.length.int > channel.recvWindow.int:
# check before allocating the buffer
raise newException(YamuxError, "Peer exhausted the recvWindow")
if header.length > 0:
var buffer = newSeqUninitialized[byte](header.length)
await m.connection.readExactly(addr buffer[0], int(header.length))
trace "Msg Rcv", msg=shortLog(buffer)
await channel.gotDataFromRemote(buffer)
if MsgFlags.Fin in header.flags:
trace "remote closed channel"
await channel.remoteClosed()
if MsgFlags.Rst in header.flags:
trace "remote reset channel"
await channel.reset()
except LPStreamEOFError as exc:
trace "Stream EOF", msg = exc.msg
except YamuxError as exc:
trace "Closing yamux connection", error=exc.msg
await m.connection.write(YamuxHeader.goAway(ProtocolError))
finally:
await m.close()
trace "Stopped yamux handler"
method getStreams*(m: Yamux): seq[Connection] =
for c in m.channels.values: result.add(c)
method newStream*(
m: Yamux,
name: string = "",
lazy: bool = false): Future[Connection] {.async.} =
if m.channels.len > m.maxChannCount - 1:
raise newException(TooManyChannels, "max allowed channel count exceeded")
let stream = m.createStream(m.currentId, true, m.windowSize, m.maxSendQueueSize)
m.currentId += 2
if not lazy:
await stream.open()
return stream
proc new*(T: type[Yamux], conn: Connection,
maxChannCount: int = MaxChannelCount,
windowSize: int = YamuxDefaultWindowSize,
maxSendQueueSize: int = MaxSendQueueSize,
inTimeout: Duration = 5.minutes,
outTimeout: Duration = 5.minutes): T =
T(
connection: conn,
currentId: if conn.dir == Out: 1 else: 2,
maxChannCount: maxChannCount,
windowSize: windowSize,
maxSendQueueSize: maxSendQueueSize,
inTimeout: inTimeout,
outTimeout: outTimeout
)