Re: [PATCH 0/4] jk/version-string and google code

From: Jeff King <peff@peff.net>
Date: Aug 10, 2012, 18:25 UTC
Message-ID: <20120810182555.GA29707@sigill.intra.peff.net>
In-Reply-To: <CAD0k6qSZYH5mvwR5PKhs1FFAPqMfRryXooxd_qhtt+eGXU7pUA@mail.gmail.com>

On Fri, Aug 10, 2012 at 11:13:30AM -0700, Dave Borowitz wrote:

Show 10 quoted lines

> > Thanks for the data point. I knew you guys ran some custom code, so I
> > wasn't sure how widespread this is. The fact that other dulwich-based
> > servers would see the same issue makes me doubly sure that my fix is the
> > right direction.
> 
> You may also notice in that code a set of innocuous_capabilities,
> which IIRC is the complete set of capabilities, at the time of
> writing, that the C git client may send without the server advertising
> them. Such a set (painstakingly assembled, I assure you :) may be
> useful as we move further in this direction.

Oh, hmm. When initially writing my message I thought that might be the case, but I checked to see that the features were sent only when the server had first advertised them. However, I didn't notice that is true only in _some_ of these lines from fetch-pack.c:

    if (multi_ack == 2)     strbuf_addstr(&c, " multi_ack_detailed");
    if (multi_ack == 1)     strbuf_addstr(&c, " multi_ack");
    if (no_done)            strbuf_addstr(&c, " no-done");
    if (use_sideband == 2)  strbuf_addstr(&c, " side-band-64k");
    if (use_sideband == 1)  strbuf_addstr(&c, " side-band");
    if (args.use_thin_pack) strbuf_addstr(&c, " thin-pack");
    if (args.no_progress)   strbuf_addstr(&c, " no-progress");
    if (args.include_tag)   strbuf_addstr(&c, " include-tag");

The early ones are checking that the server claimed support, but all of the args.* ones are influenced directly by the arguments, whether the server supports it or not.

I don't think there's any bug here. They are all of a class of features where the client can handle the case where the server simply ignores the request. However it is certainly food for thought if we are considering tightening git's server side (even if we fix these, we have to support the innocuous capabilities list forever for older clients).

-Peff