Re: [usefor] Issue with ABNF grammar in RFC 5536

[Michael Bäuerle <[e-mail]>]

Julien ÉLIE wrote:
> 
> Hi all,
> 
> Paul Kyzivat noticed in the IETF Gen-ART mailing-list
>    https://www.ietf.org/mail-archive/web/gen-art/current/msg14921.html
> that there is an issue in the ABNF of RFC 5536 (USEFOR).
> 
> RFC 5536 defines the following extension:
> 
>     fields          =/ *( approved /
>                           archive /
>                           control /
>                           distribution /
>                           expires /
>                           followup-to /
>                           injection-date /
>                           injection-info /
>                           lines /
>                           newsgroups /
>                           organization /
>                           path /
>                           summary /
>                           supersedes /
>                           user-agent /
>                           xref )
> 
> to the following element in RFC 5322:
> 
>     fields          =   *(trace
>                           *optional-field /
>                           *(resent-date /
>                            resent-from /
>                            resent-sender /
>                            resent-to /
>                            resent-cc /
>                            resent-bcc /
>                            resent-msg-id))
>                         *(orig-date /
>                         from /
>                         sender /
>                         reply-to /
>                         to /
>                         cc /
>                         bcc /
>                         message-id /
>                         in-reply-to /
>                         references /
>                         subject /
>                         comments /
>                         keywords /
>                         optional-field)

Hi Julien,

there is Erratum 2950 (Status: Held for Document Update) that specify
it like this:

   fields          =   *(trace
                         *optional-field /
                         1*(resent-date /
                           resent-from /
                           resent-sender /
                           resent-to /
                           resent-cc /
                           resent-bcc /
                           resent-msg-id))
                       *(orig-date /
                       from /
                       sender /
                       reply-to /
                       to /
                       cc /
                       bcc /
                       message-id /
                       in-reply-to /
                       references /
                       subject /
                       comments /
                       keywords /
                       optional-field)

> and a message is defined this way:
> 
>     message         =   (fields / obs-fields)
>                         [CRLF body]
> 
> 
> 
> It appears that the extension done in RFC 5536 is wrong because of how 
> "fields" is constructed in RFC 5322; as a matter of fact, (*a *b) in RFC 
> 5322 is extended to (*a *b) / *c in RFC 5536 whereas (*a *b *c) was wanted.
> 
> I believe an erratum should be filled to RFC 5536.  Maybe by just 
> changing the wording in Section 3:
> 
>     The following news header fields extend those defined in Section 3.6
>     of [RFC5322]:
> 
>       fields        =/ *( approved /
>                           archive /
>                           control /
>                           distribution /
>                           expires /
>                           followup-to /
>                           injection-date /
>                           injection-info /
>                           lines /
>                           newsgroups /
>                           organization /
>                           path /
>                           summary /
>                           supersedes /
>                           user-agent /
>                           xref )
> 
> to:
> 
>     The following news header fields are defined by this document:
> 
>       news-fields    =    approved /
>                           archive /
>                           control /
>                           distribution /
>                           expires /
>                           followup-to /
>                           injection-date /
>                           injection-info /
>                           lines /
>                           newsgroups /
>                           organization /
>                           path /
>                           summary /
>                           supersedes /
>                           user-agent /
>                           xref
> 
>     The definition of message in Section 3.5 of [RFC5322] is changed to:
> 
>       message       =   *(fields / obs-fields / news-fields)
                          ^
>                         [CRLF body]

Wouldn't this asterisk introduce the same "infinite loop of empty
strings" situation as in the erratum noted above?


-- 
Michael Bäuerle