nim-libp2p-experimental/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.
import chronos
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import nimcrypto/utils, chronicles
import types,
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../../connection,
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../../utility,
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../../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
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id: uint64
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msgType: MessageType
data: seq[byte]
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InvalidMplexMsgType = object of CatchableError
proc newInvalidMplexMsgType*(): ref InvalidMplexMsgType =
newException(InvalidMplexMsgType, "invalid message type")
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proc readMsg*(conn: Connection): Future[Msg] {.async, gcsafe.} =
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let header = await conn.readVarint()
trace "read header varint", varint = header
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let data = await conn.readLp(MaxMsgSize)
trace "read data", dataLen = data.len, data = shortLog(data)
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let msgType = header and 0x7
if msgType.int > ord(MessageType.ResetOut):
raise newInvalidMplexMsgType()
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result = (header shr 3, MessageType(msgType), data)
proc writeMsg*(conn: Connection,
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id: uint64,
msgType: MessageType,
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data: seq[byte] = @[]) {.async, gcsafe.} =
trace "sending data over mplex", id,
msgType,
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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", error = exc.name
trace "Could not write to connection - verbose", msg = exc.msg
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proc writeMsg*(conn: Connection,
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id: uint64,
msgType: MessageType,
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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!
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result = conn.writeMsg(id, msgType, cast[seq[byte]](data))