nim-libp2p/libp2p/multistream.nim

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## Nim-LibP2P
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## Copyright (c) 2019 Status Research & Development GmbH
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## 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 sequtils, strutils, strformat
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import chronos, chronicles
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import connection,
varint,
vbuffer,
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protocols/protocol
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logScope:
topic = "Multistream"
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const MsgSize* = 64*1024
const Codec* = "/multistream/1.0.0"
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const MSCodec* = "\x13" & Codec & "\n"
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const Na = "\x03na\n"
const Ls = "\x03ls\n"
type
MultisteamSelectException = object of CatchableError
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Matcher* = proc (proto: string): bool {.gcsafe.}
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HandlerHolder* = object
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proto*: string
protocol*: LPProtocol
match*: Matcher
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MultisteamSelect* = ref object of RootObj
handlers*: seq[HandlerHolder]
codec*: string
na: string
ls: string
proc newMultistream*(): MultisteamSelect =
new result
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result.codec = MSCodec
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result.ls = Ls
result.na = Na
proc select*(m: MultisteamSelect,
conn: Connection,
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proto: seq[string]):
Future[string] {.async.} =
trace "initiating handshake", codec = m.codec
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## select a remote protocol
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await conn.write(m.codec) # write handshake
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if proto.len() > 0:
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trace "selecting proto", proto = proto
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await conn.writeLp((proto[0] & "\n")) # select proto
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result = cast[string](await conn.readLp()) # read ms header
result.removeSuffix("\n")
if result != Codec:
trace "handshake failed", codec = result
return ""
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if proto.len() == 0: # no protocols, must be a handshake call
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return
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result = cast[string](await conn.readLp()) # read the first proto
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trace "reading first requested proto"
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result.removeSuffix("\n")
if result == proto[0]:
trace "succesfully selected ", proto = proto
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return
if not result.len > 0:
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trace "selecting one of several protos"
for p in proto[1..<proto.len()]:
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await conn.writeLp((p & "\n")) # select proto
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result = cast[string](await conn.readLp()) # read the first proto
result.removeSuffix("\n")
if result == p:
trace "selected protocol", protocol = result
break
proc select*(m: MultisteamSelect,
conn: Connection,
proto: string): Future[bool] {.async.} =
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if proto.len > 0:
result = (await m.select(conn, @[proto])) == proto
else:
result = (await m.select(conn, @[])) == Codec
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proc select*(m: MultisteamSelect, conn: Connection): Future[bool] =
m.select(conn, "")
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proc list*(m: MultisteamSelect,
conn: Connection): Future[seq[string]] {.async.} =
## list remote protos requests on connection
if not await m.select(conn):
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return
await conn.write(m.ls) # send ls
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var list = newSeq[string]()
let ms = cast[string](await conn.readLp())
for s in ms.split("\n"):
if s.len() > 0:
list.add(s)
result = list
proc handle*(m: MultisteamSelect, conn: Connection) {.async, gcsafe.} =
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trace "handle: starting multistream handling"
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while not conn.closed:
var ms = cast[string](await conn.readLp())
ms.removeSuffix("\n")
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trace "handle: got request for ", ms
if ms.len() <= 0:
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trace "handle: invalid proto"
await conn.write(m.na)
if m.handlers.len() == 0:
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trace "handle: sending `na` for protocol ", protocol = ms
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await conn.write(m.na)
continue
case ms:
of "ls":
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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:
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trace "found handler for", protocol = ms
await conn.writeLp((h.proto & "\n"))
try:
await h.protocol.handler(conn, ms)
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return
except Exception as exc:
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warn "exception while handling ", msg = exc.msg
warn "no handlers for ", protocol = ms
await conn.write(m.na)
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proc addHandler*[T: LPProtocol](m: MultisteamSelect,
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codec: string,
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protocol: T,
matcher: Matcher = nil) =
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## register a protocol
# TODO: This is a bug in chronicles,
# it break if I uncoment this line.
# Which is almost the same as the
# one on the next override of addHandler
#
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# trace "registering protocol", codec = codec
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m.handlers.add(HandlerHolder(proto: codec,
protocol: protocol,
match: matcher))
proc addHandler*[T: LPProtoHandler](m: MultisteamSelect,
codec: string,
handler: T,
matcher: Matcher = nil) =
## helper to allow registering pure handlers
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trace "registering proto handler", codec = codec
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let protocol = new LPProtocol
protocol.codec = codec
protocol.handler = handler
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m.handlers.add(HandlerHolder(proto: codec,
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protocol: protocol,
match: matcher))