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

44 lines
1.4 KiB
Nim

## Nim-LibP2P
## Copyright (c) 2018 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 ../../connection, ../../varint,
../../vbuffer, mplex, types,
../../stream/lpstream
proc readHeader*(conn: Connection): Future[(uint, MessageType)] {.async, gcsafe.} =
var
header: uint
length: int
res: VarintStatus
var buffer = newSeq[byte](10)
try:
for i in 0..<len(buffer):
await conn.readExactly(addr buffer[i], 1)
res = LP.getUVarint(buffer.toOpenArray(0, i), length, header)
if res == VarintStatus.Success:
return (header shr 3, MessageType(header and 0x7))
if res != VarintStatus.Success:
buffer.setLen(0)
return
except LPStreamIncompleteError:
buffer.setLen(0)
proc writeHeader*(conn: Connection,
id: int,
msgType: MessageType,
size: int) {.async, gcsafe.} =
## write lenght prefixed
var buf = initVBuffer()
buf.writeVarint(LPSomeUVarint(id.uint shl 3 or msgType.uint))
if size > 0:
buf.writeVarint(LPSomeUVarint(size.uint))
buf.finish()
result = conn.write(buf.buffer)