nim-libp2p/libp2p/multistream.nim

184 lines
5.5 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,
errors,
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
MultistreamHandshakeException* = object of CatchableError
proc newMultistreamHandshakeException*(): ref CatchableError {.inline.} =
result = newException(MultistreamHandshakeException,
"could not perform multistream handshake")
proc newMultistream*(): MultistreamSelect =
new result
result.codec = MSCodec
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
result = string.fromBytes((await conn.readLp(1024))) # read ms header
result.removeSuffix("\n")
if result != Codec:
notice "handshake failed", codec = result.toHex()
raise newMultistreamHandshakeException()
if proto.len() == 0: # no protocols, must be a handshake call
return
result = string.fromBytes(await conn.readLp(1024)) # read the first proto
trace "reading first requested proto"
result.removeSuffix("\n")
if result == proto[0]:
trace "successfully selected ", proto = proto[0]
return
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
result = string.fromBytes(await conn.readLp(1024)) # read the first proto
result.removeSuffix("\n")
if result == p:
trace "selected protocol", protocol = result
break
proc select*(m: MultistreamSelect,
conn: Connection,
proto: string): Future[bool] {.async.} =
if proto.len > 0:
result = (await m.select(conn, @[proto])) == proto
else:
result = (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) {.async, gcsafe.} =
trace "handle: starting multistream handling"
try:
while not conn.closed:
var ms = string.fromBytes(await conn.readLp(1024))
ms.removeSuffix("\n")
trace "handle: got request for ", 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:
await conn.write(m.codec)
else:
for h in m.handlers:
if (not isNil(h.match) and h.match(ms)) or ms == h.proto:
trace "found handler for", protocol = ms
await conn.writeLp((h.proto & "\n"))
await h.protocol.handler(conn, ms)
return
debug "no handlers for ", protocol = ms
await conn.write(Na)
except CatchableError as exc:
trace "exception in multistream", exc = exc.msg
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))