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EXP: When max-clients-per-query is reached, drop the first event

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When max-client-per-query value is reached, drop the first event, not
the last one.
This commit is contained in:
Ondřej Surý
2023-02-01 09:52:19 +01:00
parent d5ee9d2447
commit 9ce0ac5dcf
1 changed files with 54 additions and 39 deletions
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lib/dns/resolver.c
+54 -39
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@@ -1711,10 +1711,51 @@ fcount_decr(fetchctx_t *fctx) {
}
}
static void
fctx_sendevent(fetchctx_t *fctx, dns_fetchevent_t *event, isc_result_t result) {
isc_task_t *task;
ISC_LIST_UNLINK(fctx->events, event, ev_link);
if (event->ev_type == DNS_EVENT_TRYSTALE) {
/*
* Not applicable to TRY STALE events, this function is
* called when the fetch has either completed or timed
* out due to resolver-query-timeout being reached.
*/
isc_task_detach((isc_task_t **)&event->ev_sender);
isc_event_free((isc_event_t **)&event);
return;
}
task = event->ev_sender;
event->ev_sender = fctx;
event->vresult = fctx->vresult;
if (!HAVE_ANSWER(fctx)) {
event->result = result;
}
INSIST(event->result != ISC_R_SUCCESS ||
dns_rdataset_isassociated(event->rdataset) ||
fctx->type == dns_rdatatype_any ||
fctx->type == dns_rdatatype_rrsig ||
fctx->type == dns_rdatatype_sig);
/*
* Negative results must be indicated in event->result.
*/
if (dns_rdataset_isassociated(event->rdataset) &&
NEGATIVE(event->rdataset))
{
INSIST(event->result == DNS_R_NCACHENXDOMAIN ||
event->result == DNS_R_NCACHENXRRSET);
}
FCTXTRACE("event");
isc_task_sendanddetach(&task, ISC_EVENT_PTR(&event));
}
static void
fctx_sendevents(fetchctx_t *fctx, isc_result_t result) {
dns_fetchevent_t *event, *next_event;
isc_task_t *task;
isc_time_t now;
/*
@@ -1737,42 +1778,8 @@ fctx_sendevents(fetchctx_t *fctx, isc_result_t result) {
event = next_event)
{
next_event = ISC_LIST_NEXT(event, ev_link);
ISC_LIST_UNLINK(fctx->events, event, ev_link);
if (event->ev_type == DNS_EVENT_TRYSTALE) {
/*
* Not applicable to TRY STALE events, this function is
* called when the fetch has either completed or timed
* out due to resolver-query-timeout being reached.
*/
isc_task_detach((isc_task_t **)&event->ev_sender);
isc_event_free((isc_event_t **)&event);
continue;
}
task = event->ev_sender;
event->ev_sender = fctx;
event->vresult = fctx->vresult;
if (!HAVE_ANSWER(fctx)) {
event->result = result;
}
INSIST(event->result != ISC_R_SUCCESS ||
dns_rdataset_isassociated(event->rdataset) ||
fctx->type == dns_rdatatype_any ||
fctx->type == dns_rdatatype_rrsig ||
fctx->type == dns_rdatatype_sig);
/*
* Negative results must be indicated in event->result.
*/
if (dns_rdataset_isassociated(event->rdataset) &&
NEGATIVE(event->rdataset))
{
INSIST(event->result == DNS_R_NCACHENXDOMAIN ||
event->result == DNS_R_NCACHENXRRSET);
}
FCTXTRACE("event");
isc_task_sendanddetach(&task, ISC_EVENT_PTR(&event));
fctx_sendevent(fctx, event, result);
}
UNLOCK(&fctx->lock);
}
@@ -10579,10 +10586,18 @@ dns_resolver_createfetch(dns_resolver_t *res, const dns_name_t *name,
uint_fast32_t spillat = atomic_load_relaxed(&res->spillat);
if (spillat != 0 && count >= spillat) {
INSIST(fctx != NULL);
dns_fetchevent_t *event = ISC_LIST_HEAD(fctx->events);
while (event != NULL && event->sigrdataset != NULL) {
event = ISC_LIST_NEXT(event, ev_link);
}
if (event != NULL) {
fctx_sendevent(fctx, event, DNS_R_DROP);
} else {
result = DNS_R_DROP;
goto unlock;
}
fctx->spilled = true;
result = DNS_R_DROP;
goto unlock;
}
} else {
result = fctx_create(res, name, type, domain, nameservers,