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

84 lines
2.4 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,
../../varint,
../../vbuffer,
../../stream/lpstream
logScope:
topic = "MplexCoder"
const DefaultChannelSize* = 1 shr 20
type
Msg* = tuple
id: uint
msgType: MessageType
data: seq[byte]
proc readMplexVarint(conn: Connection): Future[uint] {.async, gcsafe.} =
var
varint: uint
length: int
res: VarintStatus
buffer = newSeq[byte](10)
try:
for i in 0..<len(buffer):
await conn.readExactly(addr buffer[i], 1)
res = PB.getUVarint(buffer.toOpenArray(0, i), length, varint)
if res == VarintStatus.Success:
break
if res != VarintStatus.Success:
raise newInvalidVarintException()
if varint.int > DefaultReadSize:
raise newInvalidVarintSizeException()
return varint
except LPStreamIncompleteError as exc:
trace "unable to read varint", exc = exc.msg
raise exc
proc readMsg*(conn: Connection): Future[Msg] {.async, gcsafe.} =
let headerVarint = await conn.readMplexVarint()
trace "read header varint", varint = headerVarint
let dataLenVarint = await conn.readMplexVarint()
trace "read data len varing", varint = dataLenVarint
var data: seq[byte]
if dataLenVarint.int > 0:
data = await conn.read(dataLenVarint.int)
trace "read data", data = data
let header = headerVarint
result = (header shr 3, MessageType(header and 0x7), data)
proc writeMsg*(conn: Connection,
id: uint,
msgType: MessageType,
data: seq[byte] = @[]) {.async, gcsafe.} =
## write lenght prefixed
var buf = initVBuffer()
buf.writePBVarint(id shl 3 or ord(msgType).uint)
buf.writePBVarint(data.len().uint) # size should be always sent
buf.finish()
try:
await conn.write(buf.buffer & data)
except LPStreamIncompleteError as exc:
trace "unable to send message", exc = exc.msg
proc writeMsg*(conn: Connection,
id: uint,
msgType: MessageType,
data: string) {.async, gcsafe.} =
result = conn.writeMsg(id, msgType, cast[seq[byte]](data))