nim-libp2p/libp2p/multistream.nim

206 lines
6.2 KiB
Nim

## Nim-LibP2P
## Copyright (c) 2019 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.
import strutils
import chronos, chronicles, stew/byteutils
import stream/connection,
vbuffer,
protocols/protocol
logScope:
topics = "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.}
HandlerHolder* = object
proto*: string
protocol*: LPProtocol
match*: Matcher
MultistreamSelect* = ref object of RootObj
handlers*: seq[HandlerHolder]
codec*: string
proc newMultistream*(): MultistreamSelect =
new result
result.codec = MSCodec
template validateSuffix(str: string): untyped =
if str.endsWith("\n"):
str.removeSuffix("\n")
else:
raise newException(CatchableError, "MultistreamSelect failed, malformed message")
proc select*(m: MultistreamSelect,
conn: Connection,
proto: seq[string]):
Future[string] {.async.} =
trace "initiating handshake", codec = m.codec
## select a remote protocol
await conn.write(m.codec) # write handshake
if proto.len() > 0:
trace "selecting proto", proto = proto[0]
await conn.writeLp((proto[0] & "\n")) # select proto
var s = string.fromBytes((await conn.readLp(1024))) # read ms header
validateSuffix(s)
if s != Codec:
notice "handshake failed", codec = s
raise newException(CatchableError, "MultistreamSelect handshake failed")
else:
trace "multistream handshake success"
if proto.len() == 0: # no protocols, must be a handshake call
return Codec
else:
s = string.fromBytes(await conn.readLp(1024)) # read the first proto
validateSuffix(s)
trace "reading first requested proto"
if s == proto[0]:
trace "successfully selected ", proto = 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", protos = protos
for p in protos:
trace "selecting proto", proto = p
await conn.writeLp((p & "\n")) # select proto
s = string.fromBytes(await conn.readLp(1024)) # read the first proto
validateSuffix(s)
if s == p:
trace "selected protocol", protocol = 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(1024))
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 "handle: starting multistream handling", handshaked = active
var handshaked = active
try:
while not conn.closed:
var ms = string.fromBytes(await conn.readLp(1024))
validateSuffix(ms)
if not handshaked and ms != Codec:
error "expected handshake message", instead=ms
raise newException(CatchableError,
"MultistreamSelect handling failed, invalid first message")
trace "handle: got request", ms
if ms.len() <= 0:
trace "handle: invalid proto"
await conn.write(Na)
if m.handlers.len() == 0:
trace "handle: sending `na` for protocol", protocol = ms
await conn.write(Na)
continue
case ms:
of "ls":
trace "handle: listing protos"
var protos = ""
for h in m.handlers:
protos &= (h.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"
await conn.write(Na)
else:
for h in m.handlers:
if (not isNil(h.match) and h.match(ms)) or ms == h.proto:
trace "found handler", protocol = ms
await conn.writeLp((h.proto & "\n"))
await h.protocol.handler(conn, ms)
return
debug "no handlers", protocol = ms
await conn.write(Na)
except CancelledError as exc:
await conn.close()
raise exc
except CatchableError as exc:
trace "exception in multistream", exc = exc.msg
await conn.close()
finally:
trace "leaving multistream loop"
proc addHandler*[T: LPProtocol](m: MultistreamSelect,
codec: string,
protocol: T,
matcher: Matcher = nil) =
## register a protocol
# TODO: This is a bug in chronicles,
# it break if I uncomment this line.
# Which is almost the same as the
# one on the next override of addHandler
#
# trace "registering protocol", codec = codec
m.handlers.add(HandlerHolder(proto: codec,
protocol: protocol,
match: matcher))
proc addHandler*[T: LPProtoHandler](m: MultistreamSelect,
codec: string,
handler: T,
matcher: Matcher = nil) =
## helper to allow registering pure handlers
trace "registering proto handler", codec = codec
let protocol = new LPProtocol
protocol.codec = codec
protocol.handler = handler
m.handlers.add(HandlerHolder(proto: codec,
protocol: protocol,
match: matcher))