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From: Stefan Eissing <stefan.eissing@greenbytes.de>
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Subject: Re: Upgrade header
Date: Mon, 3 Apr 2017 13:25:29 +0200
References: <928d0b55-b18b-480b-820a-cadcfe800b22@hoentjen.eu>
To: dev@httpd.apache.org
In-Reply-To: <928d0b55-b18b-480b-820a-cadcfe800b22@hoentjen.eu>
Message-Id: <84D9EBA1-42D6-4903-AEB8-E47BFC1C5398@greenbytes.de>
archived-at: Mon, 03 Apr 2017 11:25:38 -0000

https://tools.ietf.org/html/rfc7230#section-6.7:

"A server MAY send an Upgrade header field in any other response to
   advertise that it implements support for upgrading to the listed
   protocols, in order of descending preference, when appropriate for a
   future request."

Yes, it is intentional to advertise this to clients on the first request
of a connection. To disable this, you can "unset" such a header via
mod_headers.

Hope this helps.

-Stefan

> Am 03.04.2017 um 13:10 schrieb Sander Hoentjen <sander@hoentjen.eu>:
> 
> Hi Stefan (and others),
> 
> Right now when I enable h2 and/or h2c Apache will respond with headers
> "Upgrade: h2,h2c" and Connection: Upgrade
> As I understand it this is the wrong way around. Only the client should
> send the Upgrade headers, and only then should the server respond with a
> 101 with the Upgrade header only specifying the proto that is being
> switched to.
> Is this a bug, or does Apache respond intentionally with the Upgrade
> header? If intentional, then what is the reason?
> 
> Regards,
> Sander