ietf-nntp DEBUG command & x9x (was: 9xx)
Clive D.W. Feather
clive at demon.net
Sat Aug 5 15:11:32 PDT 2000
Russ Allbery said:
>> Clive also suggested
>> to make a best guess based on first digit.
>
> The only problem that I have with making decisions based on the first
> digit is what to do with commands that normally return multiline
> responses? If you guess that an unrecognized code is actually the
> expected return (the beginning of a multiline response) and that code
> isn't actually beginning a multiline response, you get into protocol
> trouble.
Yes, I thought about that but couldn't see any good answers.
Thoughts:
* If the command doesn't have any multiline responses, assume that unknown
codes are not multiline.
* If all legitimate 2XX responses are multiline (I don't think we have
any multiline responses that *aren't* 2XX, do we ?), then assume that
an unknown 2XX is multiline, but nothing else is.
* If some 2XX responses are multiline, but not all, it's harder.
* You could send something innocuous and unusual, like DATE, then:
- if the next line of input begins 111, the odd response was on its own;
- otherwise the next line was multiline, so skip down to the dot.
* You could assume that any further lines will appear within 10 seconds,
so do a read with timeout on the socket.
--
Clive D.W. Feather | Work: <clive at demon.net> | Tel: +44 20 8371 1138
Internet Expert | Home: <clive at davros.org> | Fax: +44 20 8371 1037
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