Re: I-D draft-petersson-forwarded-for-00.txt

On Tue, Apr 19, 2011 at 07:53:33AM +0000, Poul-Henning Kamp wrote:
> In message <8F735513-6A44-4043-B7DA-EAE1E2FD1A0D@mnot.net>, Mark Nottingham wri
> tes:
> 
> >> Forwarded: for=5.6.7.8:3456, for=8.9.1.2;by=4.5.6.7
> >> Forwarded: for=1.2.3.4:5678;by=4.3.2.1:3128;proto=https
> 
> This format needs a strict definition to be unambigious.
> 
> For instance, if the first proxy adds only "for" and the next adds
> only "by", there is no way to tell if one or two proxies were
> involved.

Yes it's easy, because each subfield is delimited by a semi-colon.
So if you have :

  Forwarded: for=1.2.3.4; by=5.6.7.8

then those are the same proxy, but if you have :

  Forwarded: for=1.2.3.4, by=5.6.7.8

then those are two distinct proxies since there are two header values.

> I still think it is a better idea that each proxy adds exactly one
> element, and that the single element contains whatever information
> the proxy is willing to disclose.

This is exactly the case : each proxy adds exactly one element here
(one header value) and it indicates the fields it wants to disclose.

Regards,
Willy