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Code Issues Releases Wiki Activity

Simplify the DNS_R_UNCHANGED handling in dns_resolver unit

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Instead of catching the DNS_R_UNCHANGED from dns_db_addrdataset() (via
cache_rrset() and dns_ncache_add()) individually, mask it properly as
soon as possible, by moving the sigrdataset caching logic inside
cache_rrset() and returning ISC_R_SUCCESS from cache_rrset() and
dns_ncache_add() when the database was unchanged.
This commit is contained in:
Ondřej Surý
2025-08-14 08:35:05 +02:00
parent 13e3c6bfe6
commit c22f156404
2 changed files with 47 additions and 50 deletions
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13
lib/dns/ncache.c
View File

@@ -17,6 +17,7 @@
#include <stdbool.h>
#include <isc/buffer.h>
#include <isc/result.h>
#include <isc/util.h>
#include <dns/db.h>
@@ -108,6 +109,7 @@ dns_ncache_add(dns_message_t *message, dns_db_t *cache, dns_dbnode_t *node,
dns_rdatalist_t ncrdatalist;
unsigned char data[65536];
unsigned int next = 0;
isc_result_t result;
/*
* Convert the authority data from 'message' into a negative cache
@@ -140,7 +142,7 @@ dns_ncache_add(dns_message_t *message, dns_db_t *cache, dns_dbnode_t *node,
isc_buffer_init(&buffer, data, sizeof(data));
MSG_SECTION_FOREACH (message, DNS_SECTION_AUTHORITY, name) {
isc_result_t result = ISC_R_SUCCESS;
result = ISC_R_SUCCESS;
if (name->attributes.ncache) {
ISC_LIST_FOREACH (name->list, rdataset, link) {
@@ -247,8 +249,13 @@ dns_ncache_add(dns_message_t *message, dns_db_t *cache, dns_dbnode_t *node,
ncrdataset.attributes.optout = true;
}
return dns_db_addrdataset(cache, node, NULL, now, &ncrdataset, 0,
addedrdataset);
result = dns_db_addrdataset(cache, node, NULL, now, &ncrdataset, 0,
addedrdataset);
if (result != ISC_R_SUCCESS && result != DNS_R_UNCHANGED) {
return result;
}
return ISC_R_SUCCESS;
}
isc_result_t

84
lib/dns/resolver.c
View File

@@ -5222,7 +5222,7 @@ static isc_result_t
cache_rrset(fetchctx_t *fctx, isc_stdtime_t now, dns_name_t *name,
dns_rdataset_t *rdataset, dns_rdataset_t *sigrdataset,
dns_dbnode_t **nodep, dns_rdataset_t *added,
dns_rdataset_t *addedsig) {
dns_rdataset_t *addedsig, bool need_validation) {
isc_result_t result = ISC_R_SUCCESS;
unsigned int options = 0;
dns_dbnode_t *node = NULL;
@@ -5265,16 +5265,33 @@ cache_rrset(fetchctx_t *fctx, isc_stdtime_t now, dns_name_t *name,
result = dns_db_addrdataset(fctx->cache, node, NULL, now,
rdataset, options, added);
}
if ((result == ISC_R_SUCCESS || result == DNS_R_UNCHANGED) &&
sigrdataset != NULL)
{
result = dns_db_addrdataset(fctx->cache, node, NULL, now,
sigrdataset, options, addedsig);
if (result == DNS_R_UNCHANGED) {
if (result == DNS_R_UNCHANGED) {
/*
* The cache wasn't updated because something was
* already there. If the data was the same as what
* we were trying to add, then sigrdataset might
* still be useful.
*/
if (!need_validation && added != NULL &&
!dns_rdataset_equals(rdataset, added))
{
/* Skip adding the sigrdataset */
} else {
/* Carry on caching the sigrdataset */
result = ISC_R_SUCCESS;
}
}
if (result == ISC_R_SUCCESS && sigrdataset != NULL) {
result = dns_db_addrdataset(fctx->cache, node, NULL, now,
sigrdataset, options, addedsig);
}
if (result == DNS_R_UNCHANGED) {
result = ISC_R_SUCCESS;
}
/*
* If we're passing a node that we looked up back to the
* caller, then we don't detach it.
@@ -5368,10 +5385,9 @@ fctx_cacheauthority(fetchctx_t *fctx, dns_message_t *message,
}
result = cache_rrset(fctx, now, name, rdataset,
sigrdataset, NULL, NULL, NULL);
if (result != ISC_R_SUCCESS &&
result != DNS_R_UNCHANGED)
{
sigrdataset, NULL, NULL, NULL,
false);
if (result != ISC_R_SUCCESS) {
continue;
}
}
@@ -5439,7 +5455,7 @@ validated(void *arg) {
* Cache the data as pending for later validation.
*/
cache_rrset(fctx, now, val->name, val->rdataset,
val->sigrdataset, NULL, NULL, NULL);
val->sigrdataset, NULL, NULL, NULL, false);
}
add_bad(fctx, message, addrinfo, result, badns_validation);
@@ -5521,7 +5537,8 @@ validated(void *arg) {
* The data was already cached as pending. Re-cache it as secure.
*/
result = cache_rrset(fctx, now, val->name, val->rdataset,
val->sigrdataset, &node, ardataset, asigrdataset);
val->sigrdataset, &node, ardataset, asigrdataset,
true);
if (result != ISC_R_SUCCESS) {
done = true;
goto cleanup;
@@ -5550,7 +5567,8 @@ answer_response:
gettrust(val->sigrdataset) == dns_trust_secure)
{
cache_rrset(fctx, now, dns_fixedname_name(&val->wild),
val->rdataset, val->sigrdataset, NULL, NULL, NULL);
val->rdataset, val->sigrdataset, NULL, NULL, NULL,
true);
}
/*
@@ -5868,33 +5886,11 @@ rctx_cache_secure(respctx_t *rctx, dns_message_t *message, dns_name_t *name,
* (if any) in two steps, so we can do an extra check
* in-between.
*/
result = cache_rrset(fctx, rctx->now, name, rdataset, NULL,
&node, ardataset, NULL);
if (result != DNS_R_UNCHANGED && result != ISC_R_SUCCESS) {
return result;
}
if (sigrdataset == NULL) {
return ISC_R_SUCCESS;
}
if (result == DNS_R_UNCHANGED && !need_validation &&
ardataset != NULL &&
!dns_rdataset_equals(rdataset, ardataset))
{
/*
* The cache wasn't updated because something was
* already there. If the data was the same as what
* we were trying to add, then sigrdataset might
* still be useful, and we should carry on caching
* it. Otherwise, move on.
*/
return ISC_R_SUCCESS;
}
result = cache_rrset(fctx, rctx->now, name, sigrdataset, NULL,
&node, asigset, NULL);
if (result != DNS_R_UNCHANGED && result != ISC_R_SUCCESS) {
result = cache_rrset(fctx, rctx->now, name, rdataset,
sigrdataset, &node, ardataset, asigset,
need_validation);
if (result != ISC_R_SUCCESS) {
return result;
}
}
@@ -5937,10 +5933,7 @@ rctx_cache_insecure(respctx_t *rctx, dns_message_t *message, dns_name_t *name,
* Cache the rdataset.
*/
result = cache_rrset(fctx, rctx->now, name, rdataset, NULL, &node,
added, NULL);
if (result == DNS_R_UNCHANGED) {
result = ISC_R_SUCCESS;
}
added, NULL, NULL);
return result;
}
@@ -6158,9 +6151,6 @@ negcache(dns_message_t *message, fetchctx_t *fctx, const dns_name_t *name,
result = dns_ncache_add(message, cache, node, covers, now, minttl,
maxttl, optout, secure, added);
if (result == DNS_R_UNCHANGED) {
result = ISC_R_SUCCESS;
}
if (added == &rdataset && dns_rdataset_isassociated(added)) {
dns_rdataset_disassociate(added);