nim-libp2p/libp2p/muxers/mplex/coder.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.
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import chronos, options, sequtils, strformat
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import nimcrypto/utils, chronicles
import types,
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../../connection,
../../varint,
../../vbuffer,
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../../stream/lpstream
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logScope:
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topic = "MplexCoder"
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type
Msg* = tuple
id: uint
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msgType: MessageType
data: seq[byte]
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proc readMplexVarint(conn: Connection): Future[Option[uint]] {.async, gcsafe.} =
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var
varint: uint
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length: int
res: VarintStatus
var buffer = newSeq[byte](10)
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result = none(uint)
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try:
for i in 0..<len(buffer):
await conn.readExactly(addr buffer[i], 1)
res = LP.getUVarint(buffer.toOpenArray(0, i), length, varint)
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if res == VarintStatus.Success:
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return some(varint)
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if res != VarintStatus.Success:
raise newInvalidVarintException()
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except LPStreamIncompleteError:
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trace "unable to read varint", exc = getCurrentExceptionMsg()
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proc readMsg*(conn: Connection): Future[Option[Msg]] {.async, gcsafe.} =
let headerVarint = await conn.readMplexVarint()
if headerVarint.isNone:
return
trace "readMsg: read header varint ", varint = headerVarint
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let dataLenVarint = await conn.readMplexVarint()
var data: seq[byte]
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if dataLenVarint.isSome and dataLenVarint.get() > 0.uint:
trace "readMsg: read size varint ", varint = dataLenVarint
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data = await conn.read(dataLenVarint.get().int)
let header = headerVarint.get()
result = some((header shr 3, MessageType(header and 0x7), data))
proc writeMsg*(conn: Connection,
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id: uint,
msgType: MessageType,
data: seq[byte] = @[]) {.async, gcsafe.} =
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## write lenght prefixed
var buf = initVBuffer()
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let header = (id shl 3 or ord(msgType).uint)
buf.writeVarint(id shl 3 or ord(msgType).uint)
buf.writeVarint(data.len().uint) # size should be always sent
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buf.finish()
await conn.write(buf.buffer & data)
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proc writeMsg*(conn: Connection,
id: uint,
msgType: MessageType,
data: string) {.async, gcsafe.} =
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result = conn.writeMsg(id, msgType, cast[seq[byte]](data))