BUG/MINOR: server-state: Fix expiration date of srvrq_check tasks

"hold.timeout" was used as expiration date for srvrq_check tasks. But it is
not accurrate. The expiration date must be based on the resolution timeouts
instead (resolve and retry).

The purpose of srvrq_check task is to clean up the server resolution status
when outdated info are inherited from the state file. Using "hold.timeout"
is not accurrate here because hold timeouts concern the resolution response
items not the resolution status of servers. It may be set to a huge value or
0. The expiration date of these tasks must be based on the resolution
timeouts instead.

So now the ("timeout resolve" + resolve_retries * "timeout retry") value is
used.

This patch should fix the issue haproxy#2816. It must be backported to all stable
versions.

(cherry picked from commit 647a290)
Signed-off-by: Willy Tarreau <[email protected]>
(cherry picked from commit 3746a7d0639ced74bb9f7cff79181be9a0f18e56)
Signed-off-by: Christopher Faulet <[email protected]>

src/server_state.c

@@ -426,7 +426,9 @@ static void srv_state_srv_update(struct server *srv, int version, char **params)
 
 		/* insert in tree and set the srvrq expiration date */
 		ebis_insert(&srv->srvrq->named_servers, &srv->host_dn);
-		task_schedule(srv->srvrq_check, tick_add(now_ms, srv->srvrq->resolvers->hold.timeout));
+		task_schedule(srv->srvrq_check, tick_add(now_ms, srv->srvrq->resolvers->timeout.resolve +
+							 srv->srvrq->resolvers->resolve_retries *
+							 srv->srvrq->resolvers->timeout.retry));
 
 		/* Unset SRV_F_MAPPORTS for SRV records.
 		 * SRV_F_MAPPORTS is unfortunately set by parse_server()