nim-libp2p-experimental/libp2p/connection.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, options, chronicles
import peerinfo,
       multiaddress,
       stream/lpstream,
       peerinfo,
       varint,
       vbuffer

const DefaultReadSize*: uint = 64 * 1024

type
  Connection* = ref object of LPStream
    peerInfo*: PeerInfo
    stream*: LPStream
    observedAddrs*: Multiaddress

  InvalidVarintException = object of LPStreamError

proc newInvalidVarintException*(): ref InvalidVarintException =
  result = newException(InvalidVarintException, "unable to prase varint")

proc newConnection*(stream: LPStream): Connection =
  ## create a new Connection for the specified async reader/writer
  new result
  result.stream = stream

method read*(s: Connection, n = -1): Future[seq[byte]] {.gcsafe.} =
  result = s.stream.read(n)

method readExactly*(s: Connection,
                    pbytes: pointer,
                    nbytes: int): 
                    Future[void] {.gcsafe.} =
  s.stream.readExactly(pbytes, nbytes)

method readLine*(s: Connection,
                 limit = 0,
                 sep = "\r\n"): 
                 Future[string] {.gcsafe.} =
  s.stream.readLine(limit, sep)

method readOnce*(s: Connection,
                 pbytes: pointer,
                 nbytes: int): 
                 Future[int] {.gcsafe.} =
  s.stream.readOnce(pbytes, nbytes)

method readUntil*(s: Connection,
                  pbytes: pointer,
                  nbytes: int,
                  sep: seq[byte]): 
                  Future[int] {.gcsafe.} =
  s.stream.readUntil(pbytes, nbytes, sep)

method write*(s: Connection, 
              pbytes: pointer, 
              nbytes: int): 
              Future[void] {.gcsafe.} =
  s.stream.write(pbytes, nbytes)

method write*(s: Connection, 
              msg: string, 
              msglen = -1): 
              Future[void] {.gcsafe.} =
  s.stream.write(msg, msglen)

method write*(s: Connection, 
              msg: seq[byte], 
              msglen = -1): 
              Future[void] {.gcsafe.} =
  s.stream.write(msg, msglen)

method close*(s: Connection) {.async, gcsafe.} =
  await s.stream.close()
  s.closed = true

proc readLp*(s: Connection): Future[seq[byte]] {.async, gcsafe.} =
  ## read lenght prefixed msg
  var
    size: uint
    length: int
    res: VarintStatus
  result = newSeq[byte](10)
  try:
    for i in 0..<len(result):
      await s.readExactly(addr result[i], 1)
      res = LP.getUVarint(result.toOpenArray(0, i), length, size)
      if res == VarintStatus.Success:
        break
    if res != VarintStatus.Success or size > DefaultReadSize:
      raise newInvalidVarintException()
    result.setLen(size)
    if size > 0.uint:
      await s.readExactly(addr result[0], int(size))
  except LPStreamIncompleteError, LPStreamReadError:
      trace "remote connection closed", exc = getCurrentExceptionMsg()

proc writeLp*(s: Connection, msg: string | seq[byte]): Future[void] {.gcsafe.} =
  ## write lenght prefixed
  var buf = initVBuffer()
  buf.writeSeq(msg)
  buf.finish()
  result = s.write(buf.buffer)

method getObservedAddrs*(c: Connection): Future[MultiAddress] {.base, async, gcsafe.} =
  ## get resolved multiaddresses for the connection
  result = c.observedAddrs

proc `$`*(conn: Connection): string =
  if conn.peerInfo.peerId.isSome:
    result = $(conn.peerInfo.peerId.get())