Re: Alt-Svc + Proxy Pac

Good question.

I think that you put the original requested URL in and let the proxy
worry about alt-svc compliance.

The proxy is your overriding alternative.  That matches the logic in
the case where the proxy.pac isn't present and you just have a
hard-coded proxy that you send all requests to.

Now, if the proxy.pac suggests that direct is acceptable, I think that
makes it OK to (try to) use the alternative.  If you think of
proxy.pac as a first level alternative selector, and alt-svc as a
second-level one, I think that works.

On 3 April 2015 at 07:35, Ryan Hamilton <> wrote:
> Howdy Folks,
> I'm curious how Alt-Svc is expect to work with Proxy PAC files. Consider the
> scenario where has an Alt-Svc that specified http/2
> on When the browser decides to make an http/2 (over
> TLS) connection to, on behalf of,
> what URL and host should the browser pass to the PAC file's
> FindProxyForURL() method?
> I can argue both cases.
> * It should pass in the requested url ( because that
> is the URL being requested. There is no other URL.
> * It should pass in a pseudo url ( because, for
> example, access to may well requires use of a proxy to
> access. By passing in the request URL, the PAC file does not have the
> opportunity to send the connection to the correct proxy.
> Thoughts?
> Cheers,
> Ryan

Received on Friday, 3 April 2015 16:51:04 UTC