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Rework dbiterator implementation

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If the iterator is paused, the tree is unlocked and may change.

In an RBT tree it's always possible to resume iteration as long
as a valid node pointer was still held, but now that the underlying
database structure is a QP trie, the iterator needs to be initialized
based on the existing structure of the trie or it will return
inconsistent results. We now call dns_qp_lookup() to reinitialize
the QP iterator whenever dbiterator_next() or dbiterator_prev() is
called on a paused iterator.
This commit is contained in:
Matthijs Mekking
2024-02-07 14:52:59 +01:00
parent 6df391d610
commit cdf62a18e7
1 changed files with 62 additions and 29 deletions
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91
lib/dns/qpdb.c
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@@ -277,8 +277,9 @@ typedef struct qpdb_dbiterator {
bool new_origin; bool new_origin;
isc_rwlocktype_t tree_locked; isc_rwlocktype_t tree_locked;
isc_result_t result; isc_result_t result;
dns_fixedname_t name;
dns_fixedname_t origin; dns_fixedname_t origin;
dns_fixedname_t fixed;
dns_name_t *name;
dns_qpiter_t iter; dns_qpiter_t iter;
dns_qpiter_t nsec3iter; dns_qpiter_t nsec3iter;
dns_qpiter_t *current; dns_qpiter_t *current;
@@ -2253,8 +2254,9 @@ dns__qpdb_createiterator(dns_db_t *db, unsigned int options,
qpdbiter->paused = true; qpdbiter->paused = true;
qpdbiter->tree_locked = isc_rwlocktype_none; qpdbiter->tree_locked = isc_rwlocktype_none;
qpdbiter->result = ISC_R_SUCCESS; qpdbiter->result = ISC_R_SUCCESS;
dns_fixedname_init(&qpdbiter->name);
dns_fixedname_init(&qpdbiter->origin); dns_fixedname_init(&qpdbiter->origin);
dns_fixedname_init(&qpdbiter->fixed);
qpdbiter->name = dns_fixedname_initname(&qpdbiter->fixed);
qpdbiter->node = NULL; qpdbiter->node = NULL;
if ((options & DNS_DB_NSEC3ONLY) != 0) { if ((options & DNS_DB_NSEC3ONLY) != 0) {
@@ -4167,7 +4169,7 @@ dereference_iter_node(qpdb_dbiterator_t *qpdbiter DNS__DB_FLARG) {
} }
static void static void
resume_iteration(qpdb_dbiterator_t *qpdbiter) { resume_iteration(qpdb_dbiterator_t *qpdbiter, bool continuing) {
dns_qpdb_t *qpdb = (dns_qpdb_t *)qpdbiter->common.db; dns_qpdb_t *qpdb = (dns_qpdb_t *)qpdbiter->common.db;
REQUIRE(qpdbiter->paused); REQUIRE(qpdbiter->paused);
@@ -4175,6 +4177,28 @@ resume_iteration(qpdb_dbiterator_t *qpdbiter) {
TREE_RDLOCK(&qpdb->tree_lock, &qpdbiter->tree_locked); TREE_RDLOCK(&qpdb->tree_lock, &qpdbiter->tree_locked);
/*
* If we're being called from dbiterator_next or _prev,
* then we may need to reinitialize the iterator to the current
* name. The tree could have changed while it was unlocked,
* would make the iterator traversal inconsistent.
*
* As long as the iterator is holding a reference to
* qpdbiter->node, the node won't be removed from the tree,
* so the lookup should always succeed.
*/
if (continuing && qpdbiter->node != NULL) {
isc_result_t result;
dns_qp_t *tree = qpdb->tree;
if (qpdbiter->current == &qpdbiter->nsec3iter) {
tree = qpdb->nsec3;
}
result = dns_qp_lookup(tree, qpdbiter->name, NULL,
qpdbiter->current, NULL, NULL, NULL);
INSIST(result == ISC_R_SUCCESS);
}
qpdbiter->paused = false; qpdbiter->paused = false;
} }
@@ -4215,7 +4239,7 @@ dbiterator_first(dns_dbiterator_t *iterator DNS__DB_FLARG) {
} }
if (qpdbiter->paused) { if (qpdbiter->paused) {
resume_iteration(qpdbiter); resume_iteration(qpdbiter, false);
} }
dereference_iter_node(qpdbiter DNS__DB_FLARG_PASS); dereference_iter_node(qpdbiter DNS__DB_FLARG_PASS);
@@ -4224,13 +4248,13 @@ dbiterator_first(dns_dbiterator_t *iterator DNS__DB_FLARG) {
case nsec3only: case nsec3only:
qpdbiter->current = &qpdbiter->nsec3iter; qpdbiter->current = &qpdbiter->nsec3iter;
dns_qpiter_init(qpdb->nsec3, qpdbiter->current); dns_qpiter_init(qpdb->nsec3, qpdbiter->current);
result = dns_qpiter_next(qpdbiter->current, NULL, result = dns_qpiter_next(qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
if (result == ISC_R_SUCCESS || result == DNS_R_NEWORIGIN) { if (result == ISC_R_SUCCESS || result == DNS_R_NEWORIGIN) {
/* If we're in the NSEC3 tree, skip the origin */ /* If we're in the NSEC3 tree, skip the origin */
if (QPDBITER_NSEC3_ORIGIN_NODE(qpdb, qpdbiter)) { if (QPDBITER_NSEC3_ORIGIN_NODE(qpdb, qpdbiter)) {
result = dns_qpiter_next( result = dns_qpiter_next(
qpdbiter->current, NULL, qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
} }
} }
@@ -4238,20 +4262,20 @@ dbiterator_first(dns_dbiterator_t *iterator DNS__DB_FLARG) {
case nonsec3: case nonsec3:
qpdbiter->current = &qpdbiter->iter; qpdbiter->current = &qpdbiter->iter;
dns_qpiter_init(qpdb->tree, qpdbiter->current); dns_qpiter_init(qpdb->tree, qpdbiter->current);
result = dns_qpiter_next(qpdbiter->current, NULL, result = dns_qpiter_next(qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
break; break;
case full: case full:
qpdbiter->current = &qpdbiter->iter; qpdbiter->current = &qpdbiter->iter;
dns_qpiter_init(qpdb->tree, qpdbiter->current); dns_qpiter_init(qpdb->tree, qpdbiter->current);
result = dns_qpiter_next(qpdbiter->current, NULL, result = dns_qpiter_next(qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
if (result == ISC_R_NOMORE) { if (result == ISC_R_NOMORE) {
qpdbiter->current = &qpdbiter->nsec3iter; qpdbiter->current = &qpdbiter->nsec3iter;
dns_qpiter_init(qpdb->nsec3, qpdbiter->current); dns_qpiter_init(qpdb->nsec3, qpdbiter->current);
result = dns_qpiter_next(qpdbiter->current, NULL, result = dns_qpiter_next(
(void **)&qpdbiter->node, qpdbiter->current, qpdbiter->name,
NULL); (void **)&qpdbiter->node, NULL);
} }
break; break;
default: default:
@@ -4263,6 +4287,7 @@ dbiterator_first(dns_dbiterator_t *iterator DNS__DB_FLARG) {
reference_iter_node(qpdbiter DNS__DB_FLARG_PASS); reference_iter_node(qpdbiter DNS__DB_FLARG_PASS);
} else { } else {
INSIST(result == ISC_R_NOMORE); /* The tree is empty. */ INSIST(result == ISC_R_NOMORE); /* The tree is empty. */
qpdbiter->node = NULL;
} }
qpdbiter->result = result; qpdbiter->result = result;
@@ -4289,7 +4314,7 @@ dbiterator_last(dns_dbiterator_t *iterator DNS__DB_FLARG) {
} }
if (qpdbiter->paused) { if (qpdbiter->paused) {
resume_iteration(qpdbiter); resume_iteration(qpdbiter, false);
} }
dereference_iter_node(qpdbiter DNS__DB_FLARG_PASS); dereference_iter_node(qpdbiter DNS__DB_FLARG_PASS);
@@ -4298,7 +4323,7 @@ dbiterator_last(dns_dbiterator_t *iterator DNS__DB_FLARG) {
case nsec3only: case nsec3only:
qpdbiter->current = &qpdbiter->nsec3iter; qpdbiter->current = &qpdbiter->nsec3iter;
dns_qpiter_init(qpdb->nsec3, qpdbiter->current); dns_qpiter_init(qpdb->nsec3, qpdbiter->current);
result = dns_qpiter_prev(qpdbiter->current, NULL, result = dns_qpiter_prev(qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
if ((result == ISC_R_SUCCESS || result == DNS_R_NEWORIGIN) && if ((result == ISC_R_SUCCESS || result == DNS_R_NEWORIGIN) &&
QPDBITER_NSEC3_ORIGIN_NODE(qpdb, qpdbiter)) QPDBITER_NSEC3_ORIGIN_NODE(qpdb, qpdbiter))
@@ -4313,13 +4338,13 @@ dbiterator_last(dns_dbiterator_t *iterator DNS__DB_FLARG) {
case nonsec3: case nonsec3:
qpdbiter->current = &qpdbiter->iter; qpdbiter->current = &qpdbiter->iter;
dns_qpiter_init(qpdb->tree, qpdbiter->current); dns_qpiter_init(qpdb->tree, qpdbiter->current);
result = dns_qpiter_prev(qpdbiter->current, NULL, result = dns_qpiter_prev(qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
break; break;
case full: case full:
qpdbiter->current = &qpdbiter->nsec3iter; qpdbiter->current = &qpdbiter->nsec3iter;
dns_qpiter_init(qpdb->nsec3, qpdbiter->current); dns_qpiter_init(qpdb->nsec3, qpdbiter->current);
result = dns_qpiter_prev(qpdbiter->current, NULL, result = dns_qpiter_prev(qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
if ((result == ISC_R_SUCCESS || result == DNS_R_NEWORIGIN) && if ((result == ISC_R_SUCCESS || result == DNS_R_NEWORIGIN) &&
QPDBITER_NSEC3_ORIGIN_NODE(qpdb, qpdbiter)) QPDBITER_NSEC3_ORIGIN_NODE(qpdb, qpdbiter))
@@ -4333,9 +4358,9 @@ dbiterator_last(dns_dbiterator_t *iterator DNS__DB_FLARG) {
if (result == ISC_R_NOMORE) { if (result == ISC_R_NOMORE) {
qpdbiter->current = &qpdbiter->iter; qpdbiter->current = &qpdbiter->iter;
dns_qpiter_init(qpdb->tree, qpdbiter->current); dns_qpiter_init(qpdb->tree, qpdbiter->current);
result = dns_qpiter_prev(qpdbiter->current, NULL, result = dns_qpiter_prev(
(void **)&qpdbiter->node, qpdbiter->current, qpdbiter->name,
NULL); (void **)&qpdbiter->node, NULL);
} }
break; break;
default: default:
@@ -4347,6 +4372,7 @@ dbiterator_last(dns_dbiterator_t *iterator DNS__DB_FLARG) {
reference_iter_node(qpdbiter DNS__DB_FLARG_PASS); reference_iter_node(qpdbiter DNS__DB_FLARG_PASS);
} else { } else {
INSIST(result == ISC_R_NOMORE); /* The tree is empty. */ INSIST(result == ISC_R_NOMORE); /* The tree is empty. */
qpdbiter->node = NULL;
} }
qpdbiter->result = result; qpdbiter->result = result;
@@ -4370,7 +4396,7 @@ dbiterator_seek(dns_dbiterator_t *iterator,
} }
if (qpdbiter->paused) { if (qpdbiter->paused) {
resume_iteration(qpdbiter); resume_iteration(qpdbiter, false);
} }
dereference_iter_node(qpdbiter DNS__DB_FLARG_PASS); dereference_iter_node(qpdbiter DNS__DB_FLARG_PASS);
@@ -4415,6 +4441,7 @@ dbiterator_seek(dns_dbiterator_t *iterator,
if (result == ISC_R_SUCCESS || result == DNS_R_PARTIALMATCH) { if (result == ISC_R_SUCCESS || result == DNS_R_PARTIALMATCH) {
qpdbiter->new_origin = true; qpdbiter->new_origin = true;
dns_name_copy(qpdbiter->node->name, qpdbiter->name);
reference_iter_node(qpdbiter DNS__DB_FLARG_PASS); reference_iter_node(qpdbiter DNS__DB_FLARG_PASS);
} else { } else {
qpdbiter->node = NULL; qpdbiter->node = NULL;
@@ -4439,12 +4466,12 @@ dbiterator_prev(dns_dbiterator_t *iterator DNS__DB_FLARG) {
} }
if (qpdbiter->paused) { if (qpdbiter->paused) {
resume_iteration(qpdbiter); resume_iteration(qpdbiter, true);
} }
dereference_iter_node(qpdbiter DNS__DB_FLARG_PASS); dereference_iter_node(qpdbiter DNS__DB_FLARG_PASS);
result = dns_qpiter_prev(qpdbiter->current, NULL, result = dns_qpiter_prev(qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
if (qpdbiter->current == &qpdbiter->nsec3iter) { if (qpdbiter->current == &qpdbiter->nsec3iter) {
@@ -4462,9 +4489,9 @@ dbiterator_prev(dns_dbiterator_t *iterator DNS__DB_FLARG) {
if (result == ISC_R_NOMORE && qpdbiter->nsec3mode == full) { if (result == ISC_R_NOMORE && qpdbiter->nsec3mode == full) {
qpdbiter->current = &qpdbiter->iter; qpdbiter->current = &qpdbiter->iter;
dns_qpiter_init(qpdb->tree, qpdbiter->current); dns_qpiter_init(qpdb->tree, qpdbiter->current);
result = dns_qpiter_prev(qpdbiter->current, NULL, result = dns_qpiter_prev(
(void **)&qpdbiter->node, qpdbiter->current, qpdbiter->name,
NULL); (void **)&qpdbiter->node, NULL);
} }
} }
@@ -4472,6 +4499,9 @@ dbiterator_prev(dns_dbiterator_t *iterator DNS__DB_FLARG) {
if (result == ISC_R_SUCCESS) { if (result == ISC_R_SUCCESS) {
reference_iter_node(qpdbiter DNS__DB_FLARG_PASS); reference_iter_node(qpdbiter DNS__DB_FLARG_PASS);
} else {
INSIST(result == ISC_R_NOMORE);
qpdbiter->node = NULL;
} }
qpdbiter->result = result; qpdbiter->result = result;
@@ -4492,12 +4522,12 @@ dbiterator_next(dns_dbiterator_t *iterator DNS__DB_FLARG) {
} }
if (qpdbiter->paused) { if (qpdbiter->paused) {
resume_iteration(qpdbiter); resume_iteration(qpdbiter, true);
} }
dereference_iter_node(qpdbiter DNS__DB_FLARG_PASS); dereference_iter_node(qpdbiter DNS__DB_FLARG_PASS);
result = dns_qpiter_next(qpdbiter->current, NULL, result = dns_qpiter_next(qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
if (result == ISC_R_NOMORE && qpdbiter->nsec3mode == full && if (result == ISC_R_NOMORE && qpdbiter->nsec3mode == full &&
@@ -4505,7 +4535,7 @@ dbiterator_next(dns_dbiterator_t *iterator DNS__DB_FLARG) {
{ {
qpdbiter->current = &qpdbiter->nsec3iter; qpdbiter->current = &qpdbiter->nsec3iter;
dns_qpiter_init(qpdb->nsec3, qpdbiter->current); dns_qpiter_init(qpdb->nsec3, qpdbiter->current);
result = dns_qpiter_next(qpdbiter->current, NULL, result = dns_qpiter_next(qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
} }
@@ -4519,7 +4549,7 @@ dbiterator_next(dns_dbiterator_t *iterator DNS__DB_FLARG) {
case nsec3only: case nsec3only:
case full: case full:
result = dns_qpiter_next( result = dns_qpiter_next(
qpdbiter->current, NULL, qpdbiter->current, qpdbiter->name,
(void **)&qpdbiter->node, NULL); (void **)&qpdbiter->node, NULL);
break; break;
case nonsec3: case nonsec3:
@@ -4536,6 +4566,9 @@ dbiterator_next(dns_dbiterator_t *iterator DNS__DB_FLARG) {
if (result == ISC_R_SUCCESS) { if (result == ISC_R_SUCCESS) {
reference_iter_node(qpdbiter DNS__DB_FLARG_PASS); reference_iter_node(qpdbiter DNS__DB_FLARG_PASS);
} else {
INSIST(result == ISC_R_NOMORE);
qpdbiter->node = NULL;
} }
qpdbiter->result = result; qpdbiter->result = result;
@@ -4555,7 +4588,7 @@ dbiterator_current(dns_dbiterator_t *iterator, dns_dbnode_t **nodep,
REQUIRE(qpdbiter->node != NULL); REQUIRE(qpdbiter->node != NULL);
if (qpdbiter->paused) { if (qpdbiter->paused) {
resume_iteration(qpdbiter); resume_iteration(qpdbiter, false);
} }
if (name != NULL) { if (name != NULL) {