From: Josh Steadmon <steadmon@google.com>
To: Stefan Beller <sbeller@google.com>
Cc: git <git@vger.kernel.org>, Jonathan Nieder <jrnieder@gmail.com>,
Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 1/1] protocol: limit max protocol version per service
Date: Wed, 10 Oct 2018 16:53:03 -0700 [thread overview]
Message-ID: <20181010235303.GB12177@google.com> (raw)
In-Reply-To: <CAGZ79kbSF5XM72SOQH7XNyjeCLqQ+AuxOqMPTspjOgk-jEgrzw@mail.gmail.com>
On 2018.10.05 12:25, Stefan Beller wrote:
> > > > I suppose if we are strict about serving from a single endpoint, the
> > > > version registry makes more sense, and individual operations can declare
> > > > acceptable version numbers before calling any network code?
> > >
> > > Ah yeah, that makes sense!
> >
> > Thinking out loud here. Please let me know if I say something stupid :)
> >
> > So we'll have (up to) three pieces of version information we'll care
> > about for version negotiation:
> >
> > 1. (maybe) a client-side protocol.version config entry
>
> (and in case we don't, we have it implicit ly hardcoded, as
> we have to choose the default for users that don't care themselves about
> this setting)
>
> > 2. a list of acceptable proto versions for the currently running
> > operation on the client
> > 3. a list of acceptable proto versions for the server endpoint that
> > handles the request
>
> Yes that matches my understanding. The issue is between (1) and (2)
> as (1) is in a generic config, whereas (2) is specific to the command,
> such that it may differ. And as a user you may want to express things
> like: "use the highest version", which is done by setting (1) to "version 2"
> despite (2) not having support of all commands for v2.
>
> > According to the doc on protocol.version: "If set, clients will attempt
> > to communicate with a server using the specified protocol version. If
> > unset, no attempt will be made by the client to communicate using a
> > particular protocol version, this results in protocol version 0 being
> > used."
> >
> > So, if protocol.version is not set, or set to 0, the client should not
> > attempt any sort of version negotiation.
>
> Yes, as version 0 is unaware of versions, i.e. there are old installations
> out there where all the versioning code is not there, so in case of an
> old client the new server *must* speak v0 to be able to communicate
> (and vice versa).
>
>
> > Otherwise, the client prefers a
> > particular version, but we don't guarantee that they will actually use
> > that version after the (unspecified) version negotiation procedure.
> >
> > If protocol.version is set to something other than 0, we construct a
> > list of acceptable versions for the given operation. If the
> > protocol.version entry is present in that list, we move it to the front
> > of the list to note that it is the preferred version. We send all of
> > these, in order, in the request.
> >
> > When the server endpoint begins to handle a request, it first constructs
> > a list of acceptable versions. If the client specifies a list of
> > versions, we check them one-by-one to see if they are acceptable. If we
> > find a match, we use that version. If we don't find any matches or if
> > the client did not send a version list, we default to v0.
> >
> > Seem reasonable?
>
> This sounds super reasonable!
So this runs into problems with remote-curl (and possibly other remote
helpers):
builtin/push.c can declare whatever allowed versions it wants, but those
are not carried over when remote-curl is started to actually talk to the
remote. What's worse, remote-curl starts its HTTP connection before it
knows what command it's actually acting as a helper for.
For now, I'm going to try adding an --allowed_versions flag for the
remote helpers, but if anyone has a better idea, let me know.
Thanks,
Josh
next prev parent reply other threads:[~2018-10-10 23:53 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-02 21:59 [PATCH 0/1] Limit client version advertisements Josh Steadmon
2018-10-02 21:59 ` [PATCH 1/1] protocol: limit max protocol version per service Josh Steadmon
2018-10-02 22:28 ` Stefan Beller
2018-10-03 21:33 ` Josh Steadmon
2018-10-03 22:47 ` Stefan Beller
2018-10-05 0:18 ` Josh Steadmon
2018-10-05 19:25 ` Stefan Beller
2018-10-10 23:53 ` Josh Steadmon [this message]
2018-10-12 23:30 ` Jonathan Nieder
2018-10-12 23:32 ` Jonathan Nieder
2018-10-12 23:45 ` Josh Steadmon
2018-10-12 23:53 ` Jonathan Nieder
2018-10-13 7:58 ` Junio C Hamano
2018-10-12 1:02 ` [PATCH v2 0/1] Advertise multiple supported proto versions steadmon
2018-10-12 1:02 ` [PATCH v2 1/1] protocol: advertise multiple supported versions steadmon
2018-10-12 22:30 ` Stefan Beller
2018-10-22 22:55 ` Josh Steadmon
2018-10-23 0:37 ` Stefan Beller
2018-11-12 21:49 ` [PATCH v3 0/1] Advertise multiple supported proto versions steadmon
2018-11-12 21:49 ` [PATCH v3 1/1] protocol: advertise multiple supported versions steadmon
2018-11-12 22:33 ` Stefan Beller
2018-11-13 3:24 ` Re* " Junio C Hamano
2018-11-13 19:21 ` Stefan Beller
2018-11-14 2:31 ` Junio C Hamano
2018-11-13 4:01 ` Junio C Hamano
2018-11-13 22:53 ` Josh Steadmon
2018-11-14 2:38 ` Junio C Hamano
2018-11-14 19:57 ` Josh Steadmon
2018-11-16 2:45 ` Junio C Hamano
2018-11-16 19:59 ` Josh Steadmon
2018-11-13 13:35 ` Junio C Hamano
2018-11-13 18:28 ` SZEDER Gábor
2018-11-13 23:03 ` Josh Steadmon
2018-11-14 0:47 ` SZEDER Gábor
2018-11-14 2:44 ` Junio C Hamano
2018-11-14 11:01 ` SZEDER Gábor
2018-11-14 2:30 ` [PATCH v4 0/1] Advertise multiple supported proto versions Josh Steadmon
2018-11-14 2:30 ` [PATCH v4 1/1] protocol: advertise multiple supported versions Josh Steadmon
2018-11-14 10:22 ` [PATCH v4 0/1] Advertise multiple supported proto versions Junio C Hamano
2018-11-14 19:51 ` Josh Steadmon
2018-11-16 10:46 ` Junio C Hamano
2018-11-16 22:34 ` [PATCH v5 " Josh Steadmon
2018-11-16 22:34 ` [PATCH v5 1/1] protocol: advertise multiple supported versions Josh Steadmon
2018-12-14 20:20 ` Ævar Arnfjörð Bjarmason
2018-12-14 21:58 ` Josh Steadmon
2018-12-14 22:39 ` Ævar Arnfjörð Bjarmason
2018-12-18 23:05 ` Josh Steadmon
2018-12-20 21:58 ` [PATCH v6 0/1] Advertise multiple supported proto versions Josh Steadmon
2018-12-20 21:58 ` [PATCH v6 1/1] protocol: advertise multiple supported versions Josh Steadmon
2019-02-05 19:42 ` Jonathan Tan
2019-02-07 23:58 ` Josh Steadmon
2019-02-11 18:53 ` Jonathan Tan
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