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

57 lines
1.7 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 types,
../../connection,
../../varint,
../../vbuffer,
../../stream/lpstream,
nimcrypto/utils
type
Phase = enum Header, Size
proc readMplexVarint(conn: Connection): Future[uint] {.async, gcsafe.} =
var
varint: 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, varint)
if res == VarintStatus.Success:
return varint
if res != VarintStatus.Success:
buffer.setLen(0)
return
except TransportIncompleteError, AsyncStreamIncompleteError:
buffer.setLen(0)
proc readMsg*(conn: Connection): Future[(uint, MessageType, seq[byte])] {.async, gcsafe.} =
let header = await conn.readMplexVarint()
let dataLen = await conn.readMplexVarint()
var data: seq[byte]
if dataLen > 0.uint:
data = await conn.read(dataLen.int)
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.writeVarint((id shl 3) or ord(msgType).uint)
buf.writeVarint(data.len().uint) # size should be always sent
buf.finish()
await conn.write(buf.buffer & data)