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Merge branch '3147-fix-more-ns_statscounter_recursclients-underflows-v9_18' into 'v9_18'

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[v9_18] Fix more ns_statscounter_recursclients underflows

See merge request isc-projects/bind9!5880
This commit is contained in:
Michał Kępień 2022-02-23 14:02:57 +00:00
commit 9862265cc9
4 changed files with 28 additions and 30 deletions
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3
CHANGES
View file

@ -1,3 +1,6 @@
5814. [bug] The RecursClients statistics counter could underflow
in certain resolution scenarios. [GL #3147]
5812. [func] Drop the artificial limit on the number of queries
processed in a single TCP read callback. [GL #3141]

6
doc/notes/notes-current.rst
View file

@ -88,3 +88,9 @@ Bug Fixes
not implemented when the BIND 9 networking stack was refactored in 9.16.
The missing functionality has been re-implemented and outgoing zone
transfers now time out properly when not progressing. :gl:`#1897`
- The statistics counter representing the current number of clients
awaiting recursive resolution results (``RecursClients``) could be
miscalculated in certain resolution scenarios, potentially causing the
value of the counter to drop below zero. This has been fixed.
:gl:`#3147`

3
lib/ns/include/ns/client.h
View file

@ -267,8 +267,7 @@ struct ns_client {
#define NS_CLIENTATTR_WANTPAD 0x08000 /*%< pad reply */
#define NS_CLIENTATTR_USEKEEPALIVE 0x10000 /*%< use TCP keepalive */
#define NS_CLIENTATTR_NOSETFC 0x20000 /*%< don't set servfail cache */
#define NS_CLIENTATTR_RECURSING 0x40000 /*%< client is recursing */
#define NS_CLIENTATTR_NOSETFC 0x20000 /*%< don't set servfail cache */
/*
* Flag to use with the SERVFAIL cache to indicate

46
lib/ns/query.c
View file

@ -2530,6 +2530,8 @@ prefetch_done(isc_task_t *task, isc_event_t *event) {
*/
if (client->recursionquota != NULL) {
isc_quota_detach(&client->recursionquota);
ns_stats_decrement(client->sctx->nsstats,
ns_statscounter_recursclients);
}
free_devent(client, &event, &devent);
@ -2557,10 +2559,15 @@ query_prefetch(ns_client_t *client, dns_name_t *qname,
if (client->recursionquota == NULL) {
result = isc_quota_attach(&client->sctx->recursionquota,
&client->recursionquota);
if (result == ISC_R_SOFTQUOTA) {
switch (result) {
case ISC_R_SUCCESS:
ns_stats_increment(client->sctx->nsstats,
ns_statscounter_recursclients);
break;
case ISC_R_SOFTQUOTA:
isc_quota_detach(&client->recursionquota);
}
if (result != ISC_R_SUCCESS) {
/* FALLTHROUGH */
default:
return;
}
}
@ -2770,10 +2777,15 @@ query_rpzfetch(ns_client_t *client, dns_name_t *qname, dns_rdatatype_t type) {
if (client->recursionquota == NULL) {
result = isc_quota_attach(&client->sctx->recursionquota,
&client->recursionquota);
if (result == ISC_R_SOFTQUOTA) {
switch (result) {
case ISC_R_SUCCESS:
ns_stats_increment(client->sctx->nsstats,
ns_statscounter_recursclients);
break;
case ISC_R_SOFTQUOTA:
isc_quota_detach(&client->recursionquota);
}
if (result != ISC_R_SUCCESS) {
/* FALLTHROUGH */
default:
return;
}
}
@ -6185,15 +6197,6 @@ fetch_callback(isc_task_t *task, isc_event_t *event) {
isc_quota_detach(&client->recursionquota);
ns_stats_decrement(client->sctx->nsstats,
ns_statscounter_recursclients);
} else if (client->attributes & NS_CLIENTATTR_RECURSING) {
client->attributes &= ~NS_CLIENTATTR_RECURSING;
/*
* Detached from recursionquota via prefetch_done(),
* but need to decrement recursive client stats here anyway,
* since it was incremented in ns_query_recurse().
*/
ns_stats_decrement(client->sctx->nsstats,
ns_statscounter_recursclients);
}
LOCK(&client->manager->reclock);
@ -6332,7 +6335,6 @@ check_recursionquota(ns_client_t *client) {
if (result == ISC_R_SUCCESS || result == ISC_R_SOFTQUOTA) {
ns_stats_increment(client->sctx->nsstats,
ns_statscounter_recursclients);
client->attributes |= NS_CLIENTATTR_RECURSING;
}
if (result == ISC_R_SOFTQUOTA) {
@ -6381,18 +6383,6 @@ check_recursionquota(ns_client_t *client) {
dns_message_clonebuffer(client->message);
ns_client_recursing(client);
} else if ((client->attributes & NS_CLIENTATTR_RECURSING) == 0) {
client->attributes |= NS_CLIENTATTR_RECURSING;
/*
* query_prefetch() attached first to client->recursionquota,
* but we must check if NS_CLIENTATTR_RECURSING attribute is
* on, if not then turn it on and increment recursing clients
* stats counter only once. The attribute is also checked in
* fetch_callback() to know if a matching decrement to this
* counter should be applied.
*/
ns_stats_increment(client->sctx->nsstats,
ns_statscounter_recursclients);
}
return (result);