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BUG/MINOR: resolvers: Don't wait periodic resolution on healthcheck failure

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DNS resoltions may be triggered via a "do-resolve" action or when a connection
failure is experienced during a healthcheck. Cached valid responses are used, if
possible. But if the entry is expired or if there is no valid response, a new
reolution should be performed. However, an resolution is only performed if the
"resolve" timeout is expired. Thus, when this comes from a healthcheck, it means
no extra resolution is performed at all.

Now, when the resolution is performed for a server (SRV or SRVEQ) and no valid
response is found, the resolution timer is reset (last_resolution is set to
TICK_ETERNITY). Of course, it is only performed if no resolution is already
running.

Note that this feature was broken 5 years ago when the resolvers code was
refactored (67957bd59e).

This patch should fix the issue #1906. It affects all stable versions. However,
it is probably a good idea to not backport it too far (2.6, maybe 2.4) and with
some delay.

(cherry picked from commit 68a61b6321)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
This commit is contained in:
Christopher Faulet 2022-10-24 08:59:59 +02:00
parent de3a7ba373
commit 98ccf10af1
1 changed files with 10 additions and 1 deletions
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11
src/resolvers.c
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@ -460,8 +460,17 @@ void resolv_trigger_resolution(struct resolv_requester *req)
* valid */
exp = tick_add(res->last_resolution, resolvers->hold.valid);
if (resolvers->t && (res->status != RSLV_STATUS_VALID ||
!tick_isset(res->last_resolution) || tick_is_expired(exp, now_ms)))
!tick_isset(res->last_resolution) || tick_is_expired(exp, now_ms))) {
/* If the resolution is not running and the requester is a
* server, reset the resoltion timer to force a quick
* resolution.
*/
if (res->step == RSLV_STEP_NONE &&
(obj_type(req->owner) == OBJ_TYPE_SERVER ||
obj_type(req->owner) == OBJ_TYPE_SRVRQ))
res->last_resolution = TICK_ETERNITY;
task_wakeup(resolvers->t, TASK_WOKEN_OTHER);
}
leave_resolver_code();
}