nim-libp2p/libp2p/multistream.nim

298 lines
9.1 KiB
Nim

# Nim-LibP2P
# Copyright (c) 2023-2024 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 std/[strutils, sequtils, tables]
import chronos, chronicles, stew/byteutils
import stream/connection,
protocols/protocol
logScope:
topics = "libp2p multistream"
const
MsgSize = 1024
Codec = "/multistream/1.0.0"
Na = "na\n"
Ls = "ls\n"
type
Matcher* = proc (proto: string): bool {.gcsafe, raises: [].}
MultiStreamError* = object of LPError
HandlerHolder* = ref object
protos*: seq[string]
protocol*: LPProtocol
match*: Matcher
openedStreams: CountTable[PeerId]
MultistreamSelect* = ref object of RootObj
handlers*: seq[HandlerHolder]
codec*: string
proc new*(T: typedesc[MultistreamSelect]): T =
T(
codec: Codec,
)
template validateSuffix(str: string): untyped =
if str.endsWith("\n"):
str.removeSuffix("\n")
else:
raise (ref MultiStreamError)(msg:
"MultistreamSelect failed, malformed message")
proc select*(
_: MultistreamSelect | type MultistreamSelect,
conn: Connection,
proto: seq[string]
): Future[string] {.async: (raises: [
CancelledError, LPStreamError, MultiStreamError]).} =
trace "initiating handshake", conn, codec = Codec
## select a remote protocol
await conn.writeLp(Codec & "\n") # write handshake
if proto.len() > 0:
trace "selecting proto", conn, proto = proto[0]
await conn.writeLp((proto[0] & "\n")) # select proto
var s = string.fromBytes((await conn.readLp(MsgSize))) # read ms header
validateSuffix(s)
if s != Codec:
notice "handshake failed", conn, codec = s
raise (ref MultiStreamError)(msg: "MultistreamSelect handshake failed")
else:
trace "multistream handshake success", conn
if proto.len() == 0: # no protocols, must be a handshake call
return Codec
else:
s = string.fromBytes(await conn.readLp(MsgSize)) # read the first proto
validateSuffix(s)
trace "reading first requested proto", conn
if s == proto[0]:
trace "successfully selected ", conn, proto = proto[0]
conn.protocol = proto[0]
return proto[0]
elif proto.len > 1:
# Try to negotiate alternatives
let protos = proto[1..<proto.len()]
trace "selecting one of several protos", conn, protos = protos
for p in protos:
trace "selecting proto", conn, proto = p
await conn.writeLp((p & "\n")) # select proto
s = string.fromBytes(await conn.readLp(MsgSize)) # read the first proto
validateSuffix(s)
if s == p:
trace "selected protocol", conn, protocol = s
conn.protocol = s
return s
return ""
else:
# No alternatives, fail
return ""
proc select*(
_: MultistreamSelect | type MultistreamSelect,
conn: Connection,
proto: string
): Future[bool] {.async: (raises: [
CancelledError, LPStreamError, MultiStreamError]).} =
if proto.len > 0:
(await MultistreamSelect.select(conn, @[proto])) == proto
else:
(await MultistreamSelect.select(conn, @[])) == Codec
proc select*(
m: MultistreamSelect,
conn: Connection
): Future[bool] {.async: (raises: [
CancelledError, LPStreamError, MultiStreamError], raw: true).} =
m.select(conn, "")
proc list*(
m: MultistreamSelect,
conn: Connection
): Future[seq[string]] {.async: (raises: [
CancelledError, LPStreamError, MultiStreamError]).} =
## list remote protos requests on connection
if not await m.select(conn):
return
await conn.writeLp(Ls) # send ls
var list = newSeq[string]()
let ms = string.fromBytes(await conn.readLp(MsgSize))
for s in ms.split("\n"):
if s.len() > 0:
list.add(s)
result = list
proc handle*(
_: type MultistreamSelect,
conn: Connection,
protos: seq[string],
matchers = newSeq[Matcher](),
active: bool = false
): Future[string] {.async: (raises: [
CancelledError, LPStreamError, MultiStreamError]).} =
trace "Starting multistream negotiation", conn, handshaked = active
var handshaked = active
while not conn.atEof:
var ms = string.fromBytes(await conn.readLp(MsgSize))
validateSuffix(ms)
if not handshaked and ms != Codec:
debug "expected handshake message", conn, instead=ms
raise (ref MultiStreamError)(msg:
"MultistreamSelect handling failed, invalid first message")
trace "handle: got request", conn, ms
if ms.len() <= 0:
trace "handle: invalid proto", conn
await conn.writeLp(Na)
case ms:
of "ls":
trace "handle: listing protos", conn
#TODO this doens't seem to follow spec, each protocol
# should be length prefixed. Not very important
# since LS is getting deprecated
await conn.writeLp(protos.join("\n") & "\n")
of Codec:
if not handshaked:
await conn.writeLp(Codec & "\n")
handshaked = true
else:
trace "handle: sending `na` for duplicate handshake while handshaked",
conn
await conn.writeLp(Na)
elif ms in protos or matchers.anyIt(it(ms)):
trace "found handler", conn, protocol = ms
await conn.writeLp(ms & "\n")
conn.protocol = ms
return ms
else:
trace "no handlers", conn, protocol = ms
await conn.writeLp(Na)
proc handle*(
m: MultistreamSelect,
conn: Connection,
active: bool = false) {.async: (raises: [CancelledError]).} =
trace "Starting multistream handler", conn, handshaked = active
var
protos: seq[string]
matchers: seq[Matcher]
for h in m.handlers:
if h.match != nil:
matchers.add(h.match)
for proto in h.protos:
protos.add(proto)
try:
let ms = await MultistreamSelect.handle(conn, protos, matchers, active)
for h in m.handlers:
if (h.match != nil and h.match(ms)) or h.protos.contains(ms):
trace "found handler", conn, protocol = ms
var protocolHolder = h
let maxIncomingStreams = protocolHolder.protocol.maxIncomingStreams
if protocolHolder.openedStreams.getOrDefault(conn.peerId) >=
maxIncomingStreams:
debug "Max streams for protocol reached, blocking new stream",
conn, protocol = ms, maxIncomingStreams
return
protocolHolder.openedStreams.inc(conn.peerId)
try:
await protocolHolder.protocol.handler(conn, ms)
finally:
protocolHolder.openedStreams.inc(conn.peerId, -1)
if protocolHolder.openedStreams[conn.peerId] == 0:
protocolHolder.openedStreams.del(conn.peerId)
return
debug "no handlers", conn, ms
except CancelledError as exc:
raise exc
except CatchableError as exc:
trace "Exception in multistream", conn, msg = exc.msg
finally:
await conn.close()
trace "Stopped multistream handler", conn
proc addHandler*(m: MultistreamSelect,
codecs: seq[string],
protocol: LPProtocol,
matcher: Matcher = nil) =
trace "registering protocols", protos = codecs
m.handlers.add(HandlerHolder(protos: codecs,
protocol: protocol,
match: matcher))
proc addHandler*(m: MultistreamSelect,
codec: string,
protocol: LPProtocol,
matcher: Matcher = nil) =
addHandler(m, @[codec], protocol, matcher)
proc addHandler*[E](
m: MultistreamSelect,
codec: string,
handler: LPProtoHandler |
proc (
conn: Connection,
proto: string): InternalRaisesFuture[void, E],
matcher: Matcher = nil) =
## helper to allow registering pure handlers
trace "registering proto handler", proto = codec
let protocol = new LPProtocol
protocol.codec = codec
protocol.handler = handler
m.handlers.add(HandlerHolder(protos: @[codec],
protocol: protocol,
match: matcher))
proc start*(m: MultistreamSelect) {.async: (raises: [CancelledError]).} =
# Nim 1.6.18: Using `mapIt` results in a seq of `.Raising([])`
var futs = newSeqOfCap[Future[void].Raising([CancelledError])](m.handlers.len)
for it in m.handlers:
futs.add it.protocol.start()
try:
await allFutures(futs)
for fut in futs:
await fut
except CancelledError as exc:
var pending: seq[Future[void].Raising([])]
doAssert m.handlers.len == futs.len, "Handlers modified while starting"
for i, fut in futs:
if not fut.finished:
pending.add noCancel fut.cancelAndWait()
elif fut.completed:
pending.add m.handlers[i].protocol.stop()
else:
static: doAssert typeof(fut).E is (CancelledError,)
await noCancel allFutures(pending)
raise exc
proc stop*(m: MultistreamSelect) {.async: (raises: []).} =
# Nim 1.6.18: Using `mapIt` results in a seq of `.Raising([CancelledError])`
var futs = newSeqOfCap[Future[void].Raising([])](m.handlers.len)
for it in m.handlers:
futs.add it.protocol.stop()
await noCancel allFutures(futs)
for fut in futs:
await fut