From: Junio C Hamano <gitster@pobox.com>
To: steadmon@google.com
Cc: git@vger.kernel.org, sbeller@google.com, jrnieder@gmail.com
Subject: Re: [PATCH v3 1/1] protocol: advertise multiple supported versions
Date: Tue, 13 Nov 2018 13:01:27 +0900 [thread overview]
Message-ID: <xmqqr2fpwrqg.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <b9968e3fb005a00e9f78627467b4fc86a6259977.1542059029.git.steadmon@google.com> (steadmon's message of "Mon, 12 Nov 2018 13:49:05 -0800")
steadmon@google.com writes:
> Currently the client advertises that it supports the wire protocol
> version set in the protocol.version config. However, not all services
> support the same set of protocol versions. When connecting to
> git-receive-pack, the client automatically downgrades to v0 if
> config.protocol is set to v2, but this check is not performed for other
> services.
"downgrades to v0 even if ... is set to v2" you mean? Otherwise it
is unclear why asking for v2 leads to using v0.
> This patch creates a protocol version registry. Individual operations
> register all the protocol versions they support prior to communicating
> with a server. Versions should be listed in preference order; the
> version specified in protocol.version will automatically be moved to the
> front of the registry.
>
> The protocol version registry is passed to remote helpers via the
> GIT_PROTOCOL environment variable.
>
> Clients now advertise the full list of registered versions. Servers
> select the first recognized version from this advertisement.
Makes sense.
> +void get_client_protocol_version_advertisement(struct strbuf *advert)
> +{
> + int tmp_nr = nr_allowed_versions;
> + enum protocol_version *tmp_allowed_versions, config_version;
> + strbuf_reset(advert);
> +
> + have_advertised_versions_already = 1;
> +
> + config_version = get_protocol_version_config();
> + if (config_version == protocol_v0) {
> + strbuf_addstr(advert, "version=0");
> + return;
> + }
> +
> + if (tmp_nr > 0) {
> + ALLOC_ARRAY(tmp_allowed_versions, tmp_nr);
> + copy_array(tmp_allowed_versions, allowed_versions, tmp_nr,
> + sizeof(enum protocol_version));
> + } else {
> + ALLOC_ARRAY(tmp_allowed_versions, 1);
> + tmp_nr = 1;
> + tmp_allowed_versions[0] = config_version;
> + }
> +
> + if (tmp_allowed_versions[0] != config_version)
> + for (int i = 1; i < nr_allowed_versions; i++)
> + if (tmp_allowed_versions[i] == config_version) {
> + enum protocol_version swap =
> + tmp_allowed_versions[0];
> + tmp_allowed_versions[0] =
> + tmp_allowed_versions[i];
> + tmp_allowed_versions[i] = swap;
> + }
> +
> + strbuf_addf(advert, "version=%s",
> + format_protocol_version(tmp_allowed_versions[0]));
> + for (int i = 1; i < tmp_nr; i++)
> + strbuf_addf(advert, ":version=%s",
> + format_protocol_version(tmp_allowed_versions[i]));
> +}
> +
So the idea is that the protocols the other end can talk come in
advert in their preferred order, and we take an intersection of them
and our "allowed-versions", but the preference is further skewed
with the "swap" thing if we have our own preference specified via
config?
I am wondering if the code added by this patch outside this
function, with if (strcmp(client_ad.buf, "version=0") sprinkled all
over the place, works sensibly when the other side says "I prefer
version=0 but I do not mind talking version=1".
Isn't tmp_allowed_versions[] leaking when we return from this
function?
next prev parent reply other threads:[~2018-11-13 4:02 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
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 [this message]
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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