nim-libp2p/libp2p/multistream.nim

218 lines
6.6 KiB
Nim

# Nim-LibP2P
# Copyright (c) 2022 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: [Defect].}
import std/[strutils, sequtils]
import chronos, chronicles, stew/byteutils
import stream/connection,
protocols/protocol
logScope:
topics = "libp2p multistream"
const
MsgSize* = 64*1024
Codec* = "/multistream/1.0.0"
MSCodec* = "\x13" & Codec & "\n"
Na* = "\x03na\n"
Ls* = "\x03ls\n"
type
Matcher* = proc (proto: string): bool {.gcsafe, raises: [Defect].}
MultiStreamError* = object of LPError
HandlerHolder* = object
protos*: seq[string]
protocol*: LPProtocol
match*: Matcher
MultistreamSelect* = ref object of RootObj
handlers*: seq[HandlerHolder]
codec*: string
proc new*(T: typedesc[MultistreamSelect]): T =
T(codec: MSCodec)
template validateSuffix(str: string): untyped =
if str.endsWith("\n"):
str.removeSuffix("\n")
else:
raise newException(MultiStreamError, "MultistreamSelect failed, malformed message")
proc select*(m: MultistreamSelect,
conn: Connection,
proto: seq[string]):
Future[string] {.async.} =
trace "initiating handshake", conn, codec = m.codec
## select a remote protocol
await conn.write(m.codec) # 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 newException(MultiStreamError, "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.tag = 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.tag = s
return s
return ""
else:
# No alternatives, fail
return ""
proc select*(m: MultistreamSelect,
conn: Connection,
proto: string): Future[bool] {.async.} =
if proto.len > 0:
return (await m.select(conn, @[proto])) == proto
else:
return (await m.select(conn, @[])) == Codec
proc select*(m: MultistreamSelect, conn: Connection): Future[bool] =
m.select(conn, "")
proc list*(m: MultistreamSelect,
conn: Connection): Future[seq[string]] {.async.} =
## list remote protos requests on connection
if not await m.select(conn):
return
await conn.write(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*(m: MultistreamSelect, conn: Connection, active: bool = false) {.async, gcsafe.} =
trace "Starting multistream handler", conn, handshaked = active
var handshaked = active
try:
while not conn.atEof:
var ms = string.fromBytes(await conn.readLp(MsgSize))
validateSuffix(ms)
if not handshaked and ms != Codec:
notice "expected handshake message", conn, instead=ms
raise newException(CatchableError,
"MultistreamSelect handling failed, invalid first message")
trace "handle: got request", conn, ms
if ms.len() <= 0:
trace "handle: invalid proto", conn
await conn.write(Na)
if m.handlers.len() == 0:
trace "handle: sending `na` for protocol", conn, protocol = ms
await conn.write(Na)
continue
case ms:
of "ls":
trace "handle: listing protos", conn
var protos = ""
for h in m.handlers:
for proto in h.protos:
protos &= (proto & "\n")
await conn.writeLp(protos)
of Codec:
if not handshaked:
await conn.write(m.codec)
handshaked = true
else:
trace "handle: sending `na` for duplicate handshake while handshaked",
conn
await conn.write(Na)
else:
for h in m.handlers:
if (not isNil(h.match) and h.match(ms)) or h.protos.contains(ms):
trace "found handler", conn, protocol = ms
await conn.writeLp(ms & "\n")
conn.tag = ms
await h.protocol.handler(conn, ms)
return
debug "no handlers", conn, protocol = ms
await conn.write(Na)
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*(m: MultistreamSelect,
codec: string,
handler: LPProtoHandler,
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.} =
await allFutures(m.handlers.mapIt(it.protocol.start()))
proc stop*(m: MultistreamSelect) {.async.} =
await allFutures(m.handlers.mapIt(it.protocol.stop()))