Re: draft-ietf-httpbis-alt-svc-latest, "9.5 Confusion Regarding Request Scheme"

On 2015-08-05 20:48, Julian Reschke wrote:
> <http://greenbytes.de/tech/webdav/draft-ietf-httpbis-alt-svc-latest.html#rfc.section.9.5>:
>
>
> "Alternative Services MUST NOT be advertised for a protocol that is not
> designed to carry the scheme. In particular, HTTP/1.1 over TLS cannot
> carry safely requests for http resources."
>
> ...which refers to the :scheme pseudo header field in HTTP/2
> (<http://greenbytes.de/tech/webdav/rfc7540.html#HttpRequest>).
>
> As far as I recall the intention of the statement above is to avoid that
> when alt-svc is used to move http traffic to a TLSsy port such as 443,
> the alternative server gets confused about whether it's serving HTTP or
> HTTPS.
>
> Recently two questions come up related to this, one raised by Stefan
> Eissing in the context of mod_h2, one off-line by people trying to use
> alt-svc for a case we may have not considered.
>
> 1) In reality, even when the protocol *does* carry the scheme (such as
> in HTTP/2), the *application* (think PHP running on top of Apache httpd)
> is so distant from the actual server stack that it wouldn't have that
> information. This is especially true as long many servers shield
> applications from any knowledge about whether they are accessed over
> HTTP/1.1 or HTTP/2. (Speaking of which, HTTP/1.1 can carry this
> information as well, see
> <http://greenbytes.de/tech/webdav/rfc7230.html#absolute-form>).

Now <https://github.com/httpwg/http-extensions/issues/91>.

> 2) The clause seems to be less relevant when alt-svc is used to
> load-balance HTTP/1.1 http*s* traffic.

Now <https://github.com/httpwg/http-extensions/issues/92>.

Best regards, Julian

Received on Thursday, 13 August 2015 17:00:55 UTC