nim-libp2p/libp2p/muxers/mplex/coder.nim

91 lines
2.8 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 chronos
import nimcrypto/utils, chronicles
import types,
../../connection,
../../utility,
../../varint,
../../vbuffer,
../../stream/lpstream
logScope:
topic = "MplexCoder"
type
Msg* = tuple
id: uint64
msgType: MessageType
data: seq[byte]
InvalidMplexMsgType = object of CatchableError
proc newInvalidMplexMsgType*(): ref InvalidMplexMsgType =
newException(InvalidMplexMsgType, "invalid message type")
proc readMsg*(conn: Connection): Future[Msg] {.async, gcsafe.} =
let header = await conn.readVarint()
trace "read header varint", varint = header
let data = await conn.readLp(MaxMsgSize)
trace "read data", dataLen = data.len, data = shortLog(data)
let msgType = header and 0x7
if msgType.int > ord(MessageType.ResetOut):
raise newInvalidMplexMsgType()
result = (header shr 3, MessageType(msgType), data)
proc writeMsg*(conn: Connection,
id: uint64,
msgType: MessageType,
data: seq[byte] = @[]) {.async, gcsafe.} =
trace "sending data over mplex", id,
msgType,
data = data.len
try:
var
left = data.len
offset = 0
while left > 0 or data.len == 0:
let
chunkSize = if left > MaxMsgSize: MaxMsgSize - 64 else: left
chunk = if chunkSize > 0 : data[offset..(offset + chunkSize - 1)] else: data
## write lenght prefixed
var buf = initVBuffer()
buf.writePBVarint(id shl 3 or ord(msgType).uint64)
buf.writePBVarint(chunkSize.uint64) # size should be always sent
buf.finish()
left = left - chunkSize
offset = offset + chunkSize
await conn.write(buf.buffer & chunk)
if data.len == 0:
return
except LPStreamEOFError:
trace "Ignoring EOF while writing"
except CancelledError as exc:
raise exc
except CatchableError as exc:
# TODO these exceptions are ignored since it's likely that if writes are
# are failing, the underlying connection is already closed - this needs
# more cleanup though
debug "Could not write to connection", msg = exc.msg
proc writeMsg*(conn: Connection,
id: uint64,
msgType: MessageType,
data: string) {.async, gcsafe.} =
# TODO: changing this to
#`await conn.writeMsg(id, msgType, cast[seq[byte]](data))`
# causes all sorts of race conditions and hangs.
# DON'T DO IT!
result = conn.writeMsg(id, msgType, cast[seq[byte]](data))