mirror of
https://github.com/isc-projects/bind9.git
synced 2026-06-09 10:32:13 -04:00
Use rcu methods to lock access view->zonetable
dns_view_find* may be called after the final call to dns_view_detach is made which detaches view->zonetable to permit the server to shutdown. We need to detect if view->zonetable is NULL during this stage and appropriately recover.
This commit is contained in:
Mark Andrews
Ondřej Surý
parent
f760ee3f8c
commit
ad747976bb
2 changed files with 142 additions and 33 deletions
154
lib/dns/view.c
154
lib/dns/view.c
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@ -30,6 +30,7 @@
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#include <isc/result.h>
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#include <isc/stats.h>
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#include <isc/string.h>
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#include <isc/urcu.h>
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#include <isc/util.h>
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#include <dns/acl.h>
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@ -133,7 +134,6 @@ dns_view_create(isc_mem_t *mctx, dns_rdataclass_t rdclass, const char *name,
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isc_rwlock_init(&view->sfd_lock);
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view->zonetable = NULL;
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dns_zt_create(mctx, view, &view->zonetable);
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result = dns_fwdtable_create(mctx, &view->fwdtable);
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@ -460,7 +460,7 @@ dns_view_detach(dns_view_t **viewp) {
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if (isc_refcount_decrement(&view->references) == 1) {
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dns_zone_t *mkzone = NULL, *rdzone = NULL;
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dns_zt_t *zt = NULL;
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dns_zt_t *zonetable = NULL;
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dns_resolver_t *resolver = NULL;
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dns_adb_t *adb = NULL;
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dns_requestmgr_t *requestmgr = NULL;
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@ -481,6 +481,15 @@ dns_view_detach(dns_view_t **viewp) {
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/* Swap the pointers under the lock */
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LOCK(&view->lock);
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rcu_read_lock();
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zonetable = rcu_xchg_pointer(&view->zonetable, NULL);
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if (zonetable != NULL) {
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if (view->flush) {
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dns_zt_flush(zonetable);
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}
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}
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rcu_read_unlock();
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if (view->resolver != NULL) {
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resolver = view->resolver;
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view->resolver = NULL;
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@ -495,14 +504,6 @@ dns_view_detach(dns_view_t **viewp) {
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requestmgr = view->requestmgr;
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view->requestmgr = NULL;
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}
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if (view->zonetable != NULL) {
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zt = view->zonetable;
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view->zonetable = NULL;
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if (view->flush) {
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dns_zt_flush(zt);
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}
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}
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if (view->managed_keys != NULL) {
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mkzone = view->managed_keys;
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view->managed_keys = NULL;
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@ -537,8 +538,9 @@ dns_view_detach(dns_view_t **viewp) {
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dns_requestmgr_detach(&requestmgr);
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}
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if (zt != NULL) {
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dns_zt_detach(&zt);
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if (zonetable != NULL) {
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synchronize_rcu();
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dns_zt_detach(&zonetable);
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}
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if (mkzone != NULL) {
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dns_zone_detach(&mkzone);
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@ -560,10 +562,16 @@ dialup(dns_zone_t *zone, void *dummy) {
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void
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dns_view_dialup(dns_view_t *view) {
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REQUIRE(DNS_VIEW_VALID(view));
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REQUIRE(view->zonetable != NULL);
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dns_zt_t *zonetable = NULL;
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(void)dns_zt_apply(view->zonetable, false, NULL, dialup, NULL);
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REQUIRE(DNS_VIEW_VALID(view));
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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(void)dns_zt_apply(zonetable, false, NULL, dialup, NULL);
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}
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rcu_read_unlock();
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}
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void
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@ -762,11 +770,19 @@ dns_view_thaw(dns_view_t *view) {
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isc_result_t
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dns_view_addzone(dns_view_t *view, dns_zone_t *zone) {
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isc_result_t result;
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dns_zt_t *zonetable = NULL;
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REQUIRE(DNS_VIEW_VALID(view));
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REQUIRE(!view->frozen);
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result = dns_zt_mount(view->zonetable, zone);
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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result = dns_zt_mount(zonetable, zone);
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} else {
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result = ISC_R_SHUTTINGDOWN;
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}
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rcu_read_unlock();
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return (result);
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}
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@ -774,9 +790,21 @@ dns_view_addzone(dns_view_t *view, dns_zone_t *zone) {
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isc_result_t
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dns_view_findzone(dns_view_t *view, const dns_name_t *name,
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dns_zone_t **zonep) {
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isc_result_t result;
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dns_zt_t *zonetable = NULL;
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REQUIRE(DNS_VIEW_VALID(view));
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return (dns_zt_find(view->zonetable, name, DNS_ZTFIND_EXACT, zonep));
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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result = dns_zt_find(zonetable, name, DNS_ZTFIND_EXACT, zonep);
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} else {
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result = ISC_R_NOTFOUND;
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}
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rcu_read_unlock();
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return (result);
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}
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isc_result_t
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@ -791,6 +819,7 @@ dns_view_find(dns_view_t *view, const dns_name_t *name, dns_rdatatype_t type,
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bool is_cache, is_staticstub_zone;
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dns_rdataset_t zrdataset, zsigrdataset;
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dns_zone_t *zone = NULL;
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dns_zt_t *zonetable = NULL;
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/*
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* Find an rdataset whose owner name is 'name', and whose type is
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@ -813,7 +842,14 @@ dns_view_find(dns_view_t *view, const dns_name_t *name, dns_rdatatype_t type,
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* Find a database to answer the query.
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*/
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is_staticstub_zone = false;
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result = dns_zt_find(view->zonetable, name, DNS_ZTFIND_MIRROR, &zone);
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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result = dns_zt_find(zonetable, name, DNS_ZTFIND_MIRROR, &zone);
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} else {
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result = ISC_R_SHUTTINGDOWN;
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}
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rcu_read_unlock();
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if (zone != NULL && dns_zone_gettype(zone) == dns_zone_staticstub &&
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!use_static_stub)
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{
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@ -1067,6 +1103,7 @@ dns_view_findzonecut(dns_view_t *view, const dns_name_t *name,
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bool is_cache, use_zone = false, try_hints = false;
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dns_zone_t *zone = NULL;
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dns_name_t *zfname = NULL;
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dns_zt_t *zonetable = NULL;
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dns_rdataset_t zrdataset, zsigrdataset;
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dns_fixedname_t zfixedname;
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unsigned int ztoptions = DNS_ZTFIND_MIRROR;
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@ -1087,7 +1124,14 @@ dns_view_findzonecut(dns_view_t *view, const dns_name_t *name,
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if ((options & DNS_DBFIND_NOEXACT) != 0) {
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ztoptions |= DNS_ZTFIND_NOEXACT;
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}
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result = dns_zt_find(view->zonetable, name, ztoptions, &zone);
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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result = dns_zt_find(zonetable, name, ztoptions, &zone);
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} else {
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result = ISC_R_SHUTTINGDOWN;
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}
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rcu_read_unlock();
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if (result == ISC_R_SUCCESS || result == DNS_R_PARTIALMATCH) {
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result = dns_zone_getdb(zone, &db);
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}
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@ -1287,11 +1331,19 @@ dns_viewlist_findzone(dns_viewlist_t *list, const dns_name_t *name,
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for (view = ISC_LIST_HEAD(*list); view != NULL;
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view = ISC_LIST_NEXT(view, link))
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{
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dns_zt_t *zonetable = NULL;
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if (!allclasses && view->rdclass != rdclass) {
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continue;
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}
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result = dns_zt_find(view->zonetable, name, DNS_ZTFIND_EXACT,
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(zone1 == NULL) ? &zone1 : &zone2);
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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result = dns_zt_find(zonetable, name, DNS_ZTFIND_EXACT,
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(zone1 == NULL) ? &zone1 : &zone2);
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} else {
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result = ISC_R_NOTFOUND;
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}
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rcu_read_unlock();
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INSIST(result == ISC_R_SUCCESS || result == ISC_R_NOTFOUND);
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if (zone2 != NULL) {
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dns_zone_detach(&zone1);
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@ -1311,15 +1363,39 @@ dns_viewlist_findzone(dns_viewlist_t *list, const dns_name_t *name,
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isc_result_t
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dns_view_load(dns_view_t *view, bool stop, bool newonly) {
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isc_result_t result;
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dns_zt_t *zonetable = NULL;
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REQUIRE(DNS_VIEW_VALID(view));
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return (dns_zt_load(view->zonetable, stop, newonly));
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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result = dns_zt_load(zonetable, stop, newonly);
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} else {
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result = ISC_R_SUCCESS;
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}
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rcu_read_unlock();
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return (result);
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}
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isc_result_t
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dns_view_asyncload(dns_view_t *view, bool newonly, dns_zt_callback_t *callback,
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void *arg) {
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isc_result_t result;
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dns_zt_t *zonetable = NULL;
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REQUIRE(DNS_VIEW_VALID(view));
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return (dns_zt_asyncload(view->zonetable, newonly, callback, arg));
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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result = dns_zt_asyncload(zonetable, newonly, callback, arg);
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} else {
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result = ISC_R_SUCCESS;
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}
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rcu_read_unlock();
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return (result);
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}
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isc_result_t
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@ -1455,10 +1531,21 @@ dns_view_flushnode(dns_view_t *view, const dns_name_t *name, bool tree) {
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isc_result_t
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dns_view_freezezones(dns_view_t *view, bool value) {
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REQUIRE(DNS_VIEW_VALID(view));
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REQUIRE(view->zonetable != NULL);
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isc_result_t result;
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dns_zt_t *zonetable = NULL;
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return (dns_zt_freezezones(view->zonetable, view, value));
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REQUIRE(DNS_VIEW_VALID(view));
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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result = dns_zt_freezezones(zonetable, view, value);
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} else {
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result = ISC_R_SUCCESS;
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}
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rcu_read_unlock();
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return (result);
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}
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isc_result_t
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@ -2119,6 +2206,7 @@ cleanup:
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void
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dns_view_setviewcommit(dns_view_t *view) {
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dns_zone_t *redirect = NULL, *managed_keys = NULL;
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dns_zt_t *zonetable = NULL;
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REQUIRE(DNS_VIEW_VALID(view));
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@ -2133,9 +2221,13 @@ dns_view_setviewcommit(dns_view_t *view) {
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UNLOCK(&view->lock);
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if (view->zonetable != NULL) {
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dns_zt_setviewcommit(view->zonetable);
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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dns_zt_setviewcommit(zonetable);
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}
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rcu_read_unlock();
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if (redirect != NULL) {
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dns_zone_setviewcommit(redirect);
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dns_zone_detach(&redirect);
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@ -2149,7 +2241,7 @@ dns_view_setviewcommit(dns_view_t *view) {
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void
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dns_view_setviewrevert(dns_view_t *view) {
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dns_zone_t *redirect = NULL, *managed_keys = NULL;
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dns_zt_t *zonetable;
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dns_zt_t *zonetable = NULL;
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REQUIRE(DNS_VIEW_VALID(view));
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@ -2164,7 +2256,6 @@ dns_view_setviewrevert(dns_view_t *view) {
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if (view->managed_keys != NULL) {
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dns_zone_attach(view->managed_keys, &managed_keys);
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}
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zonetable = view->zonetable;
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UNLOCK(&view->lock);
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if (redirect != NULL) {
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@ -2175,9 +2266,12 @@ dns_view_setviewrevert(dns_view_t *view) {
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dns_zone_setviewrevert(managed_keys);
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dns_zone_detach(&managed_keys);
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}
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rcu_read_lock();
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zonetable = rcu_dereference(view->zonetable);
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if (zonetable != NULL) {
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dns_zt_setviewrevert(zonetable);
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}
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rcu_read_unlock();
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}
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bool
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@ -28,6 +28,7 @@
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#include <isc/buffer.h>
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#include <isc/loop.h>
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#include <isc/timer.h>
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#include <isc/urcu.h>
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#include <isc/util.h>
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#include <dns/db.h>
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@ -56,13 +57,18 @@ count_zone(dns_zone_t *zone, void *uap) {
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ISC_LOOP_TEST_IMPL(apply) {
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isc_result_t result;
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dns_zone_t *zone = NULL;
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dns_zt_t *zt = NULL;
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int nzones = 0;
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result = dns_test_makezone("foo", &zone, NULL, true);
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assert_int_equal(result, ISC_R_SUCCESS);
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view = dns_zone_getview(zone);
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assert_non_null(view->zonetable);
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rcu_read_lock();
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zt = rcu_dereference(view->zonetable);
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rcu_read_unlock();
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assert_non_null(zt);
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assert_int_equal(nzones, 0);
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result = dns_zt_apply(view->zonetable, false, NULL, count_zone,
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@ -151,6 +157,7 @@ ISC_LOOP_TEST_IMPL(asyncload_zone) {
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isc_result_t result;
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int n;
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dns_zone_t *zone = NULL;
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dns_zt_t *zt = NULL;
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char buf[4096];
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result = dns_test_makezone("foo", &zone, NULL, true);
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@ -161,7 +168,10 @@ ISC_LOOP_TEST_IMPL(asyncload_zone) {
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assert_int_equal(result, ISC_R_SUCCESS);
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view = dns_zone_getview(zone);
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assert_non_null(view->zonetable);
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rcu_read_lock();
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zt = rcu_dereference(view->zonetable);
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rcu_read_unlock();
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assert_non_null(zt);
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assert_false(dns__zone_loadpending(zone));
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zonefile = fopen("./zone.data", "wb");
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@ -239,7 +249,9 @@ ISC_LOOP_TEST_IMPL(asyncload_zt) {
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dns_zone_setfile(zone3, TESTS_DIR "/testdata/zt/nonexistent.db",
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dns_masterformat_text, &dns_master_style_default);
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zt = view->zonetable;
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rcu_read_lock();
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zt = rcu_dereference(view->zonetable);
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rcu_read_unlock();
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assert_non_null(zt);
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dns_test_setupzonemgr();
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@ -254,7 +266,10 @@ ISC_LOOP_TEST_IMPL(asyncload_zt) {
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assert_false(dns__zone_loadpending(zone2));
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assert_false(atomic_load(&done));
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rcu_read_lock();
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zt = rcu_dereference(view->zonetable);
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dns_zt_asyncload(zt, false, all_done, NULL);
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rcu_read_unlock();
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}
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ISC_TEST_LIST_START
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