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9780 :: Is flags={SocketFlag.Peek} buggy or am I missing something ?

• void09 (orginal) [2022-12-30T01:46:29+01:00] view original

  I have this code with asyncSocket on linux:

  while true:
    var msgSize = ""
    while msgSize.len == 0:
        try:
          msgSize = await asocket.recv(4, flags={SocketFlag.Peek})
          await sleepAsync(200)
        except ...
      try:
        resp = await asocket.recv(4 + msg2Int(msgSize))
      (proces message...)
  Run

  This works as expected, until I get a larger message (16kB, confirmed with wireshark that I actually receive it). What happens is that it gets stuck on recv the first 4 bytes in peek mode, it stays at 0, even though I have not gotten the data out of the socket buffer. If I remove the Peek flag, and adjust the code (remove +4 from the second recv size), I get the expected data.

  https://man7.org/linux/man-pages/man2/recv.2.html :

  MSG_PEEK

  This flag causes the receive operation to return data from the beginning of the receive queue without removing that data from the queue. Thus, a subsequent receive call will return the same data.

  Any idea what could be going on ?

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