Subject: RFC 3143

From: Julian Reschke <[email-masked]>
Date: Thu, 11 Dec 2008 16:20:31 +0100

Hi,

I was recently pointed to RFC 3143, "Known HTTP Proxy/Caching Problems" 
(<http://tools.ietf.org/html/rfc3143>).

This one is interesting in that it claims to document several problems 
in the HTTP/1.1 *specification*. If these claims are correct, we should 
add the individual points to our issues tracker. If they are not, we 
should file errata against RFC 3143.

 From a quick read, at least two issues look fishy:

1) "2.1.1 Vary header is underspecified and/or misleading" 
(<http://tools.ietf.org/html/rfc3143#section-2.1.1>)

This includes an example using HTTP delta encoding, but *claims* that 
the problem also occurs in simpler cases. I'm not ready to believe that 
claim yet.

2) "2.2.2 Interception proxies prevent introduction of new HTTP methods" 
(<http://tools.ietf.org/html/rfc3143#section-2.2.2>)

This claims:

       A proxy that receives a request with a method unknown to it is
       required to generate an HTTP 501 Error as a response.  HTTP
       methods are designed to be extensible so there may be applications
       deployed with initial support just for the user agent and origin
       server.  An interception proxy that hijacks requests which include
       new methods destined for servers that have implemented those
       methods creates a de-facto firewall where none may be intended.

...without pointing out where RFC 2616 says that.

Feedback appreciated,

Julian

---

From: Mark Nottingham <[email-masked]>
Date: Fri, 12 Dec 2008 21:55:39 +1100

Well, 3143 is Informational, and IIRC it was considered as a way to  
collect industry / community experience at that point in time, not an  
authoritative list of errata, etc.

I would treat it as an input document to this work, not necessarily  
something we have to correct, refute, or harmonise with. If we're  
interested in correcting other existing documents, I think BCP56 is  
more important than this one...

Cheers,

On 12/12/2008, at 2:20 AM, Julian Reschke wrote:

>
> Hi,
>
> I was recently pointed to RFC 3143, "Known HTTP Proxy/Caching  
> Problems" (<http://tools.ietf.org/html/rfc3143>).
>
> This one is interesting in that it claims to document several  
> problems in the HTTP/1.1 *specification*. If these claims are  
> correct, we should add the individual points to our issues tracker.  
> If they are not, we should file errata against RFC 3143.
>
> 1) "2.1.1 Vary header is underspecified and/or misleading" (<http://tools.ietf.org/html/rfc3143#section-2.1.1 
> >)
>
> This includes an example using HTTP delta encoding, but *claims*  
> that the problem also occurs in simpler cases. I'm not ready to  
> believe that claim yet.
>
> 2) "2.2.2 Interception proxies prevent introduction of new HTTP  
> methods" (<http://tools.ietf.org/html/rfc3143#section-2.2.2>)
>
> This claims:
>

--
Mark Nottingham     http://www.mnot.net/

---

From: Julian Reschke <[email-masked]>
Date: Fri, 12 Dec 2008 13:51:31 +0100

Mark Nottingham wrote:
> interested in correcting other existing documents, I think BCP56 is more 
> important than this one...

It is.

On the other hand, advice like "you can't use extension methods because 
of a proxy requirement in RFC 2616" should be corrected. Does anybody 
recall the background of that? 
(<http://tools.ietf.org/html/rfc3143#section-2.2.2>)?

BR, Julian

---

From: Yves Lafon <[email-masked]>
Date: Fri, 12 Dec 2008 10:30:26 -0500 (EST)

On Fri, 12 Dec 2008, Julian Reschke wrote:

> On the other hand, advice like "you can't use extension methods because of a 
> proxy requirement in RFC 2616" should be corrected. Does anybody recall the 
> background of that? (<http://tools.ietf.org/html/rfc3143#section-2.2.2>)?

Well, it's interception proxies, not identified proxies where you know (or 
not) what to expect. If an interception proxy can't forward the request, 
then I would consider it as a bug, and I don't recall that rfc2616 ever 
said that.

-- 
Baroula que barouleras, au tiéu toujou t'entourneras.

         ~~Yves