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BUG/MEDIUM: tcp-check: unbreak multiple connect rules again 

The last connect rule used to be ignored and that was fixed by commit
248f1173f ("BUG/MEDIUM: tcp-check: single connect rule can't detect
DOWN servers") during 1.9 development. However this patch went a bit
too far by not breaking out of the loop after a pending connect(),
resulting in a series of failed connect() to be quickly skipped and
only the last one to be taken into account.

Technically speaking the series is not exactly skipped, it's just that
TCP checks suffer from a design issue which is that there is no
distinction between a new rule and this rule's completion in the
"connect" rule handling code. As such, when evaluating TCPCHK_ACT_CONNECT
a new connection is created regardless of any previous connection in
progress, and the previous result is ignored. It seems that this issue
is mostly specific to the connect action if we refer to the comments at
the top of the function, so it might be possible to durably address it
by reworking the connect state.

For now this patch does something simpler, it restores the behaviour
before the commit above consisting in breaking out of the loop when
the connection is in progress and after skipping comment rules. This
way we fall back to the default code waiting for completion.

This patch must be backported as far as 1.8 since the commit above
was backported there. Thanks to Jrme Magnin for reporting and
bisecting this issue.
This commit is contained in:
Willy Tarreau 2019-07-15 10:57:51 +02:00
parent 9cca8dfc0b
commit 7df8ca6296
1 changed files with 4 additions and 0 deletions
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4
src/checks.c
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@ -2960,6 +2960,10 @@ static int tcpcheck_main(struct check *check)
if (&check->current_step->list == head)
break;
/* don't do anything until the connection is established */
if (!(conn->flags & CO_FL_CONNECTED))
break;
} /* end 'connect' */
else if (check->current_step->action == TCPCHK_ACT_SEND) {
/* mark the step as started */