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Use stale on error also when unable to recurse

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The 'query_usestale()' function was only called when in
'query_gotanswer()' and an unexpected error occurred. This may have
been "quota reached", and thus we were in some cases returning
stale data on fetch-limits (and if serve-stale enabled of course).

But we can also hit fetch-limits when recursing because we are
following a referral (in 'query_notfound()' and
'query_delegation_recurse()'). Here we should also check for using
stale data in case an error occurred.

Specifically don't check for using stale data when refetching a
zero TTL RRset from cache.

Move the setting of DNS_DBFIND_STALESTART into the 'query_usestale()'
function to avoid code duplication.
This commit is contained in:
Matthijs Mekking
2021-02-04 13:57:01 +01:00
parent a415424339
commit 8bcd7fe69e
1 changed files with 26 additions and 10 deletions
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36
lib/ns/query.c
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@@ -7440,7 +7440,7 @@ root_key_sentinel_return_servfail(query_ctx_t *qctx, isc_result_t result) {
* return true; otherwise, return false. * return true; otherwise, return false.
*/ */
static bool static bool
query_usestale(query_ctx_t *qctx) { query_usestale(query_ctx_t *qctx, isc_result_t result) {
if ((qctx->client->query.dboptions & DNS_DBFIND_STALEOK) != 0) { if ((qctx->client->query.dboptions & DNS_DBFIND_STALEOK) != 0) {
/* /*
* Query was already using stale, if that didn't work the * Query was already using stale, if that didn't work the
@@ -7459,6 +7459,13 @@ query_usestale(query_ctx_t *qctx) {
dns_resolver_destroyfetch(&qctx->client->query.fetch); dns_resolver_destroyfetch(&qctx->client->query.fetch);
} }
/*
* Start the stale-refresh-time window in case there was a
* resolver query timeout.
*/
if (qctx->resuming && result == ISC_R_TIMEDOUT) {
qctx->client->query.dboptions |= DNS_DBFIND_STALESTART;
}
return (true); return (true);
} }
@@ -7556,19 +7563,11 @@ query_gotanswer(query_ctx_t *qctx, isc_result_t res) {
"query_gotanswer: unexpected error: %s", "query_gotanswer: unexpected error: %s",
isc_result_totext(result)); isc_result_totext(result));
CCTRACE(ISC_LOG_ERROR, errmsg); CCTRACE(ISC_LOG_ERROR, errmsg);
if (query_usestale(qctx)) { if (query_usestale(qctx, result)) {
/* /*
* If serve-stale is enabled, query_usestale() already * If serve-stale is enabled, query_usestale() already
* set up 'qctx' for looking up a stale response. * set up 'qctx' for looking up a stale response.
*
* We only need to check if the query timed out or
* something else has gone wrong. If the query timed
* out, we will start the stale-refresh-time window.
*/ */
if (qctx->resuming && result == ISC_R_TIMEDOUT) {
qctx->client->query.dboptions |=
DNS_DBFIND_STALESTART;
}
return (query_lookup(qctx)); return (query_lookup(qctx));
} }
@@ -8527,6 +8526,13 @@ query_notfound(query_ctx_t *qctx) {
qctx->client->query.attributes |= qctx->client->query.attributes |=
NS_QUERYATTR_DNS64EXCLUDE; NS_QUERYATTR_DNS64EXCLUDE;
} }
} else if (query_usestale(qctx, result)) {
/*
* If serve-stale is enabled, query_usestale()
* already set up 'qctx' for looking up a
* stale response.
*/
return (query_lookup(qctx));
} else { } else {
QUERY_ERROR(qctx, result); QUERY_ERROR(qctx, result);
} }
@@ -8831,6 +8837,12 @@ query_delegation_recurse(query_ctx_t *qctx) {
qctx->client->query.attributes |= qctx->client->query.attributes |=
NS_QUERYATTR_DNS64EXCLUDE; NS_QUERYATTR_DNS64EXCLUDE;
} }
} else if (query_usestale(qctx, result)) {
/*
* If serve-stale is enabled, query_usestale() already set up
* 'qctx' for looking up a stale response.
*/
return (query_lookup(qctx));
} else { } else {
QUERY_ERROR(qctx, result); QUERY_ERROR(qctx, result);
} }
@@ -10225,6 +10237,10 @@ query_zerottl_refetch(query_ctx_t *qctx) {
NS_QUERYATTR_DNS64EXCLUDE; NS_QUERYATTR_DNS64EXCLUDE;
} }
} else { } else {
/*
* There was a zero ttl from the cache, don't fallback to
* serve-stale lookup.
*/
QUERY_ERROR(qctx, result); QUERY_ERROR(qctx, result);
} }