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From: Jeff King <peff@peff.net>
To: steadmon@google.com
Cc: git@vger.kernel.org
Subject: Re: [PATCH] remote-curl: die on server-side errors
Date: Tue, 13 Nov 2018 09:26:24 -0500	[thread overview]
Message-ID: <20181113142624.GA17128@sigill.intra.peff.net> (raw)
In-Reply-To: <9a89e54e79593f6455b52e01d802695362f4ec21.1542062657.git.steadmon@google.com>

On Mon, Nov 12, 2018 at 02:44:56PM -0800, steadmon@google.com wrote:

> When a smart HTTP server sends an error message via pkt-line,
> remote-curl will fail to detect the error (which usually results in
> incorrectly falling back to dumb-HTTP mode).
> 
> This patch adds a check in discover_refs() for server-side error
> messages, as well as a test case for this issue.

Aside from the reformatting of the conditional that Junio mentioned,
this seems pretty good to me. But while looking at that, I found a few
things, some old and some new. :)

> diff --git a/remote-curl.c b/remote-curl.c
> index 762a55a75f..bb3a86505e 100644
> --- a/remote-curl.c
> +++ b/remote-curl.c
> @@ -436,7 +436,9 @@ static struct discovery *discover_refs(const char *service, int for_push)
>  	} else if (maybe_smart &&
>  		   last->len > 5 && starts_with(last->buf + 4, "version 2")) {
>  		last->proto_git = 1;
> -	}
> +	} else if (maybe_smart && last->len > 5 &&
> +		   starts_with(last->buf + 4, "ERR "))
> +		die(_("remote error: %s"), last->buf + 8);

The magic "4" here and in the existing "version 2" check is because we
are expecting pkt-lines. The original conditional always calls
packed_read_line_buf() and will complain if we didn't actually get a
pkt-line.

Should we confirm that we got a real packet-line? Or at least that those
first four are even plausible hex chars?

I admit that it's pretty unlikely that the server is going to fool us
here. It would need something like "foo ERRORS ARE FUN!". And even then
we'd report an error (whereas the correct behavior is falling back to
dumb http, but we know that won't work anyway because that's not a valid
ref advertisement). So I doubt this is really a bug per se, but it might
make it easier to understand what's going on if we actually parsed the
packet.

Similarly, we seem eager to accept "version 2" even if we are only
expecting v0. I know you have another series working in that direction,
but I don't think it touches this "proto_git". I guess accepting
"version 2" as "we're speaking git protocol" and then barfing later with
"wait, I didn't mean to speak v2" is probably OK.

-Peff

  parent reply	other threads:[~2018-11-13 14:26 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-12 22:44 [PATCH] remote-curl: die on server-side errors steadmon
2018-11-12 22:55 ` Stefan Beller
2018-11-13  2:52 ` Junio C Hamano
2018-11-13  3:02 ` Junio C Hamano
2018-11-13 22:15   ` Josh Steadmon
2018-11-13 14:26 ` Jeff King [this message]
2018-11-13 22:25   ` Josh Steadmon
2018-11-14  0:49     ` Jeff King
2018-11-14  7:00       ` Jeff King
2018-11-15 21:51         ` Josh Steadmon
2018-11-16  8:44           ` [PATCH 0/3] remote-curl smart-http discovery cleanup Jeff King
2018-11-16  8:47             ` [PATCH 1/3] remote-curl: refactor smart-http discovery Jeff King
2018-11-16 20:27               ` Josh Steadmon
2019-02-05 23:29               ` Junio C Hamano
2019-02-06 19:16                 ` Jeff King
2019-02-06 19:18                   ` Jeff King
2019-02-06 19:29                     ` Josh Steadmon
2019-02-06 20:42                       ` Junio C Hamano
2019-02-06 21:14                       ` Jeff King
2019-02-06 19:18                   ` [PATCH 2/3] remote-curl: tighten "version 2" check for smart-http Jeff King
2019-02-06 19:19                   ` [PATCH 3/3] t5551: test server-side ERR packet Jeff King
2019-02-06 22:19                   ` [PATCH 1/3] remote-curl: refactor smart-http discovery Junio C Hamano
2018-11-16  8:48             ` [PATCH 2/3] remote-curl: tighten "version 2" check for smart-http Jeff King
2018-11-16 20:28               ` Josh Steadmon
2018-11-16  8:49             ` [PATCH 3/3] remote-curl: die on server-side errors Jeff King
2018-11-16 20:04             ` [PATCH 0/3] remote-curl smart-http discovery cleanup Josh Steadmon
2018-12-12  0:25             ` [PATCH v3 0/4] Unify pkt-line error handling and refactor smart-http Josh Steadmon
2018-12-12  0:25               ` [PATCH v3 1/4] pack-protocol.txt: accept error packets in any context Josh Steadmon
2018-12-12 11:02                 ` Jeff King
2018-12-13  1:17                   ` Masaya Suzuki
2018-12-13  8:04                     ` Jeff King
2018-12-13 22:18                     ` Josh Steadmon
2018-12-17 21:33                       ` Jeff King
2018-12-19 23:30                         ` Josh Steadmon
2018-12-20 15:49                           ` Jeff King
2018-12-12  0:25               ` [PATCH v3 2/4] remote-curl: refactor smart-http discovery Josh Steadmon
2018-12-12  0:25               ` [PATCH v3 3/4] remote-curl: tighten "version 2" check for smart-http Josh Steadmon
2018-12-12  0:25               ` [PATCH v3 4/4] lib-httpd, t5551: check server-side HTTP errors Josh Steadmon
2018-12-12  8:43               ` [PATCH v3 0/4] Unify pkt-line error handling and refactor smart-http Junio C Hamano
2018-11-13 14:30 ` [PATCH] remote-curl: die on server-side errors Junio C Hamano
2018-11-13 22:28   ` Josh Steadmon

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