Subject: Struggling with LWS (2616) vs LWSP (2831bis)

From: Julian Reschke <[email-masked]>
Date: Mon, 26 May 2008 17:59:57 +0200

Ok...

RFC2616 has:

   LWS = [CRLF] 1*( SP | HTAB )

Substituting "SP | HTAB" by "WSP" (as defined in RFC5234) gets us to

   LWS = [CRLF] 1*WSP

Now, 
<http://tools.ietf.org/html/draft-ietf-sasl-rfc2831bis-12#section-7.1> has:

   LWSP = *(WSP / CRLF WSP)

which can be rewritten as

   LWSP = *([CRLF] WSP)

(right?)

which seems to equivalent to RFC2616's *LWS:

   STARLWS = *([CRLF] 1*WSP)

So should RFC2616bis adopt the LWSP production used in RFC5234?

BR, Julian

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From: "Frank Ellermann" <[email-masked]>
Date: Tue, 27 May 2008 11:37:16 +0200

Julian Reschke wrote:

> should RFC2616bis adopt the LWSP production used in RFC5234?

You can use it in a "MUST NOT generate, MUST accept" section
about obsolete syntax, same idea as obs-FWS in 2822 + 2822upd.

The LWSP problem are "apparently empty lines" in the header.

For mail and news the sound solution is FWS excluding obs-FWS,
folding is okay, but each folded line has to contain non-WSP
(= not only white space).

 Frank

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From: Julian Reschke <[email-masked]>
Date: Tue, 27 May 2008 11:46:29 +0200

> (= not only white space).

Understood; but that's a separate discussion.

For now, I'm just trying to make progress on the ABNF conversion; *not* 
on changing the allowed syntax (for which I think we don't have 
consensus yet).

BR, Julian

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From: "Frank Ellermann" <[email-masked]>
Date: Tue, 27 May 2008 13:42:59 +0200

Julian Reschke wrote:
 
> For now, I'm just trying to make progress on the ABNF conversion;
> *not* on changing the allowed syntax (for which I think we don't
> have consensus yet).

Fine, for 2831bis I arrived at 
<http://article.gmane.org/gmane.ietf.sasl/2758>
amended by
<http://article.gmane.org/gmane.ietf.sasl/2759>
using the definition  LWSP = *(WSP / CRLF WSP)

That's the same LWSP as in STD 68 with "apparently empty lines".

To fix this *later* you can simply replace LWSP by FWS (RFC 2822):

FWS     = ([*WSP CRLF] 1*WSP) / obs-FWS

*Later* put the "multi-CRLF" crap into <obs-FWS>, and say that it
MUST NOT be generated, compare RFC 2822 chapter 4.2.  The syntax
for <obs-FWS> could be improved, I didn't see that in the 2822upd
discussions:

obs-FWS = 1*WSP *(CRLF 1*WSP)

I think that should be obs-FWS = 1*WSP 2*(CRLF 1*WSP) or similar.

 Frank