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Allow zero length keys in isc_hashmap

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In case, we are trying to hash the empty key into the hashmap, the key
is going to have zero length.  This might happen in the unit test.
Allow this and add a unit test to ensure the empty zero-length key
doesn't hash to slot 0 as SipHash 2-4 (our hash function of choice) has
no problem with zero-length inputs.
This commit is contained in:
Ondřej Surý 2022-12-08 10:46:09 +01:00
parent 8a35d52807
commit 7cefcb6184
No known key found for this signature in database
GPG key ID: 2820F37E873DEA41
2 changed files with 29 additions and 5 deletions
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9
lib/isc/hashmap.c
View file

@ -134,7 +134,7 @@ try_nexttable(const isc_hashmap_t *hashmap, uint8_t idx) {
static void
hashmap_node_init(hashmap_node_t *node, const uint32_t hashval,
const uint8_t *key, const uint32_t keysize, void *value) {
REQUIRE(key != NULL && keysize > 0 && keysize <= UINT16_MAX);
REQUIRE(key != NULL && keysize <= UINT16_MAX);
*node = (hashmap_node_t){
.value = value,
@ -318,7 +318,6 @@ uint32_t
isc_hashmap_hash(const isc_hashmap_t *hashmap, const void *key,
uint32_t keysize) {
REQUIRE(ISC_HASHMAP_VALID(hashmap));
REQUIRE(key != NULL && keysize > 0 && keysize <= UINT16_MAX);
uint32_t hashval;
@ -332,7 +331,7 @@ isc_result_t
isc_hashmap_find(const isc_hashmap_t *hashmap, const uint32_t *hashvalp,
const void *key, uint32_t keysize, void **valuep) {
REQUIRE(ISC_HASHMAP_VALID(hashmap));
REQUIRE(key != NULL && keysize > 0 && keysize <= UINT16_MAX);
REQUIRE(key != NULL && keysize <= UINT16_MAX);
hashmap_node_t *node;
uint8_t idx = hashmap->hindex;
@ -487,7 +486,7 @@ isc_result_t
isc_hashmap_delete(isc_hashmap_t *hashmap, const uint32_t *hashvalp,
const void *key, uint32_t keysize) {
REQUIRE(ISC_HASHMAP_VALID(hashmap));
REQUIRE(key != NULL && keysize > 0 && keysize <= UINT16_MAX);
REQUIRE(key != NULL && keysize <= UINT16_MAX);
hashmap_node_t *node;
isc_result_t result = ISC_R_NOTFOUND;
@ -600,7 +599,7 @@ isc_result_t
isc_hashmap_add(isc_hashmap_t *hashmap, const uint32_t *hashvalp,
const void *key, uint32_t keysize, void *value) {
REQUIRE(ISC_HASHMAP_VALID(hashmap));
REQUIRE(key != NULL && keysize > 0 && keysize <= UINT16_MAX);
REQUIRE(key != NULL && keysize <= UINT16_MAX);
isc_result_t result;
uint32_t hashval = (hashvalp != NULL)

25
tests/isc/hashmap_test.c
View file

@ -351,6 +351,30 @@ ISC_RUN_TEST_IMPL(isc_hashmap_iterator) {
return;
}
ISC_RUN_TEST_IMPL(isc_hashmap_hash_zero_length) {
isc_hashmap_t *hashmap = NULL;
uint32_t hashval;
bool again = false;
again:
isc_hashmap_create(mctx, 1, ISC_HASHMAP_CASE_SENSITIVE, &hashmap);
hashval = isc_hashmap_hash(hashmap, "", 0);
isc_hashmap_destroy(&hashmap);
if (hashval == 0 && !again) {
/*
* We could be extremely unlock and the siphash could hash the
* zero length string to 0, so try one more time.
*/
again = true;
goto again;
}
assert_int_not_equal(hashval, 0);
}
ISC_RUN_TEST_IMPL(isc_hashmap_case) {
isc_result_t result;
isc_hashmap_t *hashmap = NULL;
@ -401,6 +425,7 @@ ISC_RUN_TEST_IMPL(isc_hashmap_case) {
}
ISC_TEST_LIST_START
ISC_TEST_ENTRY(isc_hashmap_hash_zero_length)
ISC_TEST_ENTRY(isc_hashmap_case)
ISC_TEST_ENTRY(isc_hashmap_1_120)
ISC_TEST_ENTRY(isc_hashmap_6_1000)