Re: Parsing the Injection-Info: header field

[Julien ÉLIE <julien@xxxxxxxxxxxxxxx>]

Hi Antti-Juhani,

> > I understand that RFC 2045 now extends the syntax of RFC 5322 (instead
> > of RFC 822).
>
> That interpretation would mean that suddenly CFWS beciame forbidden in MIME
> constructs when RFC 2822 was published.  I don't think that was the intent,
> especially when "those mechanisms are outside of the scope".

CFWS is not forbidden by RFC 2822/5322.  It just became obsolete syntax:

4. Obsolete Syntax

  Earlier versions of this specification allowed for different (usually
  more liberal) syntax than is allowed in this version.

  [...]

  Though these syntactic
  forms MUST NOT be generated according to the grammar in section 3,
  they MUST be accepted and parsed by a conformant receiver.

  [...]

  One important difference between the obsolete (interpreting) and the
  current (generating) syntax is that in structured header field bodies
  (i.e., between the colon and the CRLF of any structured header
  field), white space characters, including folding white space, and
  comments could be freely inserted between any syntactic tokens.  This
  allowed many complex forms that have proven difficult for some
  implementations to parse.


That's why I find weird that RFC 5536 still encourages an obsolete syntax
(with the posting-host example) that MUST NOT be generated.

I believe the interpretation of the fact that RFC 2045 now extends the
syntax of RFC 5322 is that:

* for RFC-5322-compliant implementation, RFC 2045 MUST comply with the
  general syntax of RFC 5322;

* for RFC-822-compliant implementation, RFC 2045 uses the general syntax
  described in RFC 822.


> That paragraph is a bit unfortunately worded, though.

I don't think so.
It is normal that an RFC-5322-compliant article does not use obsolete
syntax.  That's what RFC 5322 mentions:  if MIME is to be used in compliance
with RFC 5322, then the allowed syntax is restricted to the one of RFC 5322.


I'm trying to write to the IETF YAM group to ask, but I don't manage to
(the same way I still do not manage to write to the W3C URI group!).

--
Julien ÉLIE

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