Re: [apps-discuss] I-D Action: draft-ietf-appsawg-rfc5451bis-04.txt

Alessandro Vesely <vesely@tana.it> Thu, 23 May 2013 07:51 UTC

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Subject: Re: [apps-discuss] I-D Action: draft-ietf-appsawg-rfc5451bis-04.txt
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On Sat 18/May/2013 00:22:47 +0200 Scott Kitterman wrote:
> 
> I believe the change from:
> 
> authres-header = "Authentication-Results:" [CFWS] authserv-id
> 	[ CFWS version ]

Note that in bis-04 it is:

 authres-header = "Authentication-Results:" [CFWS] authserv-id
        [ [CFWS] authres-version ]

The optional space allows:

   Authentication-Results: example.org1; none

> to:
> 
> authres-header = "Authentication-Results:" [CFWS] authserv-id	
> 	[ [CFWS] "/" [CFWS] authres-version ]
> 
> is an incompatible change and if you really want to make it, you should bump 
> the version number.  I checked and with authres, your example is mis-parsed.
> 
> 	Authentication-Results: example.org/1; none
> 
> In this example, the authserv-id is "example.org", but authres, using the RFC 
> 5451 ABNF parses this and determines the authserv-id is "example.org/1"
> 
> If you want to make this change, I think it needs to be version 2 because an 
> existing version 1 parser can't parse the header field anymore.

STD 68 specifies how to define a formal syntax, but that doesn't have
to be a first-order syntax, so its parseability can depend on the
semantics.  The ABNF rules defined in the I-D don't lend themselves to
automated generation of lexical analyzers:  In order to parse the
identifier and understand which ADMD it refers to, it is necessary to
adhere to some naming convention, which is purposely left unspecified.