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make sure the command length header data be 4 bytes #153

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Aug 29, 2019
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make sure the command length header data be 4 bytes #153

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6 changes: 6 additions & 0 deletions naz/client.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1852,6 +1852,12 @@ async def receive_data(self, TESTING: bool = False) -> typing.Union[None, bytes]
# `client.reader` and `client.writer` should not have timeouts since they are non-blocking
# https://github.com/komuw/naz/issues/116
command_length_header_data = await self.reader.read(4)

# make sure the header data be 4 bytes
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@jwenjian I wonder if using await self.reader.readexactly(4)[1] would be better?
although that raises IncompleteReadError[2] which we would have to handle somehow.

  1. https://docs.python.org/3.6/library/asyncio-stream.html#asyncio.StreamReader.readexactly
  2. https://docs.python.org/3.6/library/asyncio-stream.html#asyncio.IncompleteReadError

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Also relevant[3].

I do not know which is better. Let me know your thoughts

  1. https://stackoverflow.com/questions/28452724/method-asyncio-streams-streamreader-readbyte-count-reads-too-few-bytes

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The readexactly method is better if we have a proper way to handle the IncompleteReadError

log an error and ignore it or raise it?

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It seems there is no timeout in the read*() functions?

So if the readexactly(4) raises an error, it means that there is no more data and the read partial bytes(length must be less than 4) is not part of an valid SMPP PDU, so I suggest to abandon it then continue the while loop.

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In my opinion, like the way you handle the message body in Line 1900, it should works fine to the headers.

also don't know which is better, so maybe we can use the way I do in this pr util we find out a more efficient way.

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thanks for your input. I think we can start with this and improve if/when it becomes neccessary

I'll think about it some more.

while len(command_length_header_data) != 4:
more_bytes = await self.reader.read(4 - len(command_length_header_data))
command_length_header_data = command_length_header_data + more_bytes

except (
ConnectionError,
TimeoutError,
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