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Re: h2 definition of HTTP2-Settings

From: Mark Nottingham <mnot@mnot.net>
Date: Wed, 3 Sep 2014 08:26:11 +0300
Cc: HTTP Working Group <ietf-http-wg@w3.org>
Message-Id: <1427C541-06A2-4C56-9D1A-3CE9F137D9E2@mnot.net>
To: Roy Fielding <fielding@gbiv.com>

On 1 Sep 2014, at 6:42 am, Roy T. Fielding <fielding@gbiv.com> wrote:

> This comment is in reference to sections 3.2.1 and 11 of
> 
> http://tools.ietf.org/id/draft-ietf-httpbis-http2-14.txt
> 
>> 3.2.1.  HTTP2-Settings Header Field
>> 
>>   A request that upgrades from HTTP/1.1 to HTTP/2 MUST include exactly
>>   one "HTTP2-Settings" header field.  The "HTTP2-Settings" header field
>>   is a hop-by-hop header field that includes parameters that govern the
>>   HTTP/2 connection, provided in anticipation of the server accepting
>>   the request to upgrade.
>> 
>>     HTTP2-Settings    = token68
> 
> There are no hop-by-hop header fields, so don't call it that.

Looks like Martin has already taken care of this editorially.


> Why use a 14 character required field-name to provide options for a
> supposedly faster protocol?  Just call it "H2.

Raised as <https://github.com/http2/http2-spec/issues/601>.

Roy, my take here is that since this is only sent once  when an upgrade is attempted  the size of the header field is less-than critical. If it were being sent on every request, itd be different, of course. Id be interested to hear what other people think.


>>   A server MUST reject an attempt to upgrade if this header field is
>>   not present.  A server MUST NOT send this header field.
>> 
>>   The content of the "HTTP2-Settings" header field is the payload of a
>>   SETTINGS frame (Section 6.5), encoded as a base64url string (that is,
>>   the URL- and filename-safe Base64 encoding described in Section 5 of
>>   [RFC4648], with any trailing '=' characters omitted).  The ABNF
>>   [RFC5234] production for "token68" is defined in Section 2.1 of
>>   [RFC7235].
>> 
>>   As a hop-by-hop header field, the "Connection" header field MUST
>>   include a value of "HTTP2-Settings" in addition to "Upgrade" when
>>   upgrading to HTTP/2.
> 
> No!  What it should say is:
> 
>   Since the upgrade is only intended to apply to the immediate connection,
>   a client sending H2 MUST also send H2 as a connection option in the
>   "Connection" header field to prevent it from being forwarded downstream.
> 
> IOW, the only thing that makes a field hop-by-hop is the requirements
> in Connection.  It is not a characteristic of the field.

Likewise, already taken care of.

--
Mark Nottingham   http://www.mnot.net/
Received on Wednesday, 3 September 2014 05:26:39 UTC

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