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Date: Mon, 11 Feb 2013 01:55:00 +0000
From: MRAB <python@mrabarnett.plus.com>
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To: python-list@python.org
Subject: Re: Python recv loop
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On 2013-02-11 00:48, Ihsan Junaidi Ibrahim wrote:
> Hi,
>
> I'm implementing a python client connecting to a C-backend server and am currently stuck to as to how to proceed with receiving variable-length byte stream coming in from the server.
>
> I have coded the first 4 bytes (in hexadecimal) of message coming in from the server to specify the length of the message payload i.e. 0xad{...}
>
> I've managed to receive and translate the message length until I reach my second recv which I readjusted the buffer size to include the new message length.
>
> However that failed and recv received 0 bytes. I implemented the same algorithm on the server side using C and it work so appreciate if you can help me on this.
>
> # receive message length
>      print 'receiving data'
>      mlen = sock.recv(4)
>      try:
>          nbuf = int(mlen, 16)
>      except ValueError as e:
>          print 'invalid length type'
>          return -1
>
>      while True:
>          buf = sock.recv(nbuf)
>
>          if not buf:
>              break
>
>      slen = len(buf)
>      str = "{0} bytes received: {1}".format(slen, buf)
>      print str
>
You should keep reading until you get all need or the connection is
closed:

     buf = b''
     while len(buf) < nbuf:
         chunk = sock.recv(nbuf - len(buf))

         if not chunk:
             break

         buf += chunk