ietf-nntp NNTP and 16-bit charsets

Clive D.W. Feather clive at demon.net
Mon Apr 30 03:59:31 PDT 2001


Charles Lindsey said:
> And then maybe we get a stream of bytes representing the 16-bit characters
> of the body which continues until we get five consecutive octets that look
> like "CFLF.CRLF".
[...]
> So I think the wording needs to be clarified. But first, we have to decide
> what we INTEND.

I think that we need to be fairly conservative about what will work, but
not overly so.

Based on other related discussions, I think that the sender needs to
assume:
- NUL is unsafe;
- CR and LF may only appear in CRLF pairs;
- any other octet value will survive transmission unchanged;
- the space between CRLF pairs should be no more than 510 octets apart;
and needs to implement dot stuffing (that is, the sequence CRLF"." within
the transmitted data is changed to CRLF"..").

As Andrew (I think) pointed out, it is possible to pervert quoted-printable
to handle this. That is, all octets are transmitted unchanged except NUL,
CR, LF, and =, which are converted to =00, =0D, etc.) and CRLF pairs are
added as necessary. Dots can also be encoded to avoid the need for
stuffing.

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Clive D.W. Feather  | Work:  <clive at demon.net>   | Tel:  +44 20 8371 1138
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