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Code Issues Releases Wiki Activity

Keep track of allow client detach

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The stale-answer-client-timeout feature introduced a dependancy on
when a client may be detached from the handle. The dboption
DNS_DBFIND_STALEONLY was reused to track this attribute. This overloads
the meaning of this database option, and actually introduced a bug
because the option was checked in other places. In particular, in
'ns_query_done()' there is a check for 'RECURSING(qctx->client) &&
(!QUERY_STALEONLY(&qctx->client->query) || ...' and the condition is
satisfied because recursion has not completed yet and
DNS_DBFIND_STALEONLY is already cleared by that time (in
query_lookup()), because we found a useful answer and we should detach
the client from the handle after sending the response.

Add a new boolean to the client structure to keep track of client
detach from handle is allowed or not. It is only disallowed if we are
in a staleonly lookup and we didn't found a useful answer.
This commit is contained in:
Matthijs Mekking
2021-03-25 14:13:35 +01:00
parent e7fe606020
commit fee164243f
2 changed files with 15 additions and 11 deletions
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25
lib/ns/query.c
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@@ -568,7 +568,7 @@ query_send(ns_client_t *client) {
inc_stats(client, counter);
ns_client_send(client);
if (!QUERY_STALEONLY(&client->query)) {
if (!client->nodetach) {
isc_nmhandle_detach(&client->reqhandle);
}
}
@@ -598,7 +598,7 @@ query_error(ns_client_t *client, isc_result_t result, int line) {
ns_client_error(client, result);
if (!QUERY_STALEONLY(&client->query)) {
if (!client->nodetach) {
isc_nmhandle_detach(&client->reqhandle);
}
}
@@ -614,7 +614,7 @@ query_next(ns_client_t *client, isc_result_t result) {
}
ns_client_drop(client, result);
if (!QUERY_STALEONLY(&client->query)) {
if (!client->nodetach) {
isc_nmhandle_detach(&client->reqhandle);
}
}
@@ -5196,7 +5196,7 @@ qctx_freedata(query_ctx_t *qctx) {
dns_db_detach(&qctx->zdb);
}
if (qctx->event != NULL && !QUERY_STALEONLY(&qctx->client->query)) {
if (qctx->event != NULL && !qctx->client->nodetach) {
free_devent(qctx->client, ISC_EVENT_PTR(&qctx->event),
&qctx->event);
}
@@ -5785,6 +5785,7 @@ query_lookup(query_ctx_t *qctx) {
* active RRset is not available.
*/
qctx->client->query.dboptions |= DNS_DBFIND_STALEONLY;
qctx->client->nodetach = true;
}
dboptions = qctx->client->query.dboptions;
@@ -5946,6 +5947,7 @@ query_lookup(query_ctx_t *qctx) {
&qctx->db);
qctx->client->query.dboptions &=
~DNS_DBFIND_STALEONLY;
qctx->client->nodetach = false;
qctx->options &= ~DNS_GETDB_STALEFIRST;
if (qctx->client->query.fetch != NULL) {
dns_resolver_destroyfetch(
@@ -5992,7 +5994,7 @@ query_lookup(query_ctx_t *qctx) {
* actually not a 'stale-only' lookup. Clear the flag to
* allow the client to be detach the handle.
*/
qctx->client->query.dboptions &= ~DNS_DBFIND_STALEONLY;
qctx->client->nodetach = false;
}
result = query_gotanswer(qctx, result);
@@ -6027,6 +6029,7 @@ query_lookup_staleonly(ns_client_t *client) {
dns_db_attach(client->view->cachedb, &qctx.db);
client->query.attributes &= ~NS_QUERYATTR_RECURSIONOK;
client->query.dboptions |= DNS_DBFIND_STALEONLY;
client->nodetach = true;
(void)query_lookup(&qctx);
if (qctx.node != NULL) {
dns_db_detachnode(qctx.db, &qctx.node);
@@ -6068,10 +6071,11 @@ fetch_callback(isc_task_t *task, isc_event_t *event) {
query_lookup_staleonly(client);
isc_event_free(ISC_EVENT_PTR(&event));
return;
} else {
client->query.dboptions &= ~DNS_DBFIND_STALEONLY;
}
client->query.dboptions &= ~DNS_DBFIND_STALEONLY;
client->nodetach = false;
LOCK(&client->query.fetchlock);
if (client->query.fetch != NULL) {
/*
@@ -11536,7 +11540,7 @@ isc_result_t
ns_query_done(query_ctx_t *qctx) {
isc_result_t result = ISC_R_UNSET;
const dns_namelist_t *secs = qctx->client->message->sections;
bool query_stale_only;
bool nodetach;
CCTRACE(ISC_LOG_DEBUG(3), "ns_query_done");
@@ -11648,10 +11652,9 @@ ns_query_done(query_ctx_t *qctx) {
* Client may have been detached after query_send(), so
* we test and store the flag state here, for safety.
*/
query_stale_only = QUERY_STALEONLY(&qctx->client->query);
nodetach = qctx->client->nodetach;
query_send(qctx->client);
if (!query_stale_only) {
if (!nodetach) {
qctx->detach_client = true;
}
return (qctx->result);