Re: [apps-discuss] I-D Action: draft-ietf-appsawg-http-forwarded-01.txt

[Julian Reschke <[e-mail]>]

On 2012-03-27 16:29, Julian Reschke wrote:
> ...

OK, details...:

>        Forwarded   = "Forwarded" ":" LWS Forwarded-v
>        Forwarded-v = 1#forwarded-element

If you use RFC2616ABNF, the LWS isn't needed here.

(If you did switch to base this on HTTPbis, I would recommend just to 
define the *value* ABNF).

>        forwarded-element =
>                OWS forwarded-value *( OWS ";" OWS forwarded-value ) OWS

I would recommend to allow leading and trailing ";"; if you don't you 
will end up with some recipients allowing them (because it's the 
simplest way to parse it) and some not doing so.

Thus:

        forwarded-element =
            [ forwarded-value ] *( ";" [ forwarded-value ] )

Also OWS isn't needed here if you use RFC2616ABNF.

(see similar discussion in websec)

>        forwarded-value   = for-kv | by-kv | proto-kv | host-kv | ext-kv
>
>        for-kv     = "for=" node
>        by-kv      = "by="  node
>        proto-kv   = "proto=" proto-name
>        host-kv    = "host=" host
>        ext-kv     =  extension "=" ext-value
>        proto-name = ALPHA *( ALPHA | DIGIT | "+" | "-" | "." )

I would change this to

    forwarded-element = token "=" value
    value             = token / quoted-string

And then define the various values independently of the base ABNF.

Example:

The syntax of a "for" value, after potential quoted-string unescaping, 
MUST conform to the "node" ABNF.

(Also, it's kind of weird to use the name "value" for something that is 
not the right-hand side of a name/value pair; would be good to make 
"forwarded-value" something else)

Finally:

>        extension = 1*( ALPHA | DIGIT | "-" )
>        ext-value = <any OCTET except CTLs, "," and ";",
>          but including SP>

This should be

   extension = token
   ext-value = token | quoted-string

for consistency with all the other values.

Best regards, Julian