| CC: | "Tony Finch" <dot@dotat.at> |
| Date: | Wed, 21 Jun 2017 18:41:29 +0100 |
| To: | bind9-bugs@isc.org |
| From: | "Tony Finch" <dot@dotat.at> |
| Subject: | [PATCH] Deprecate dns_name_hashbylabel() since it isn't a very good hash. |
The rbt stopped using it in 2004 (change 1740) and it was
not used after that point until RRL started using it in 2013.
I have left the entry points in place for backwards compatibility,
though the hash values will be different.
---
lib/dns/include/dns/name.h | 16 ----------------
lib/dns/name.c | 34 ++++------------------------------
lib/dns/rrl.c | 4 ++--
3 files changed, 6 insertions(+), 48 deletions(-)
diff --git a/lib/dns/include/dns/name.h b/lib/dns/include/dns/name.h
index ab76458..346188e 100644
--- a/lib/dns/include/dns/name.h
+++ b/lib/dns/include/dns/name.h
@@ -349,22 +349,6 @@ dns_name_fullhash(const dns_name_t *name, isc_boolean_t case_sensitive);
*\li A hash value
*/
-unsigned int
-dns_name_hashbylabel(const dns_name_t *name, isc_boolean_t case_sensitive);
-/*%<
- * Provide a hash value for 'name', where the hash value is the sum
- * of the hash values of each label.
- *
- * Note: if 'case_sensitive' is ISC_FALSE, then names which differ only in
- * case will have the same hash value.
- *
- * Requires:
- *\li 'name' is a valid name
- *
- * Returns:
- *\li A hash value
- */
-
/*
*** Comparisons
***/
diff --git a/lib/dns/name.c b/lib/dns/name.c
index d07b5fc..b41740b 100644
--- a/lib/dns/name.c
+++ b/lib/dns/name.c
@@ -498,38 +498,12 @@ dns_fullname_hash(const dns_name_t *name, isc_boolean_t case_sensitive) {
unsigned int
dns_name_hashbylabel(const dns_name_t *name, isc_boolean_t case_sensitive) {
- unsigned char *offsets;
- dns_offsets_t odata;
- dns_name_t tname;
- unsigned int h = 0;
- unsigned int i;
-
/*
- * Provide a hash value for 'name'.
+ * This function was deprecated because of its poor performance.
+ * We only keep this internally to provide binary backward
+ * compatibility.
*/
- REQUIRE(VALID_NAME(name));
-
- if (name->labels == 0)
- return (0);
- else if (name->labels == 1)
- return (isc_hash_function_reverse(name->ndata, name->length,
- case_sensitive, NULL));
-
- SETUP_OFFSETS(name, offsets, odata);
- DNS_NAME_INIT(&tname, NULL);
- tname.labels = 1;
- h = 0;
- for (i = 0; i < name->labels; i++) {
- tname.ndata = name->ndata + offsets[i];
- if (i == name->labels - 1)
- tname.length = name->length - offsets[i];
- else
- tname.length = offsets[i + 1] - offsets[i];
- h += isc_hash_function_reverse(tname.ndata, tname.length,
- case_sensitive, NULL);
- }
-
- return (h);
+ return (dns_name_fullhash(name, case_sensitive));
}
dns_namereln_t
diff --git a/lib/dns/rrl.c b/lib/dns/rrl.c
index 252ebd8..53a86d3 100644
--- a/lib/dns/rrl.c
+++ b/lib/dns/rrl.c
@@ -417,10 +417,10 @@ make_key(const dns_rrl_t *rrl, dns_rrl_key_t *key,
{
dns_name_init(&base, base_offsets);
dns_name_getlabelsequence(qname, 1, labels-1, &base);
- key->s.qname_hash = dns_name_hashbylabel(&base,
+ key->s.qname_hash = dns_name_fullhash(&base,
ISC_FALSE);
} else {
- key->s.qname_hash = dns_name_hashbylabel(qname,
+ key->s.qname_hash = dns_name_fullhash(qname,
ISC_FALSE);
}
}
--
2.10.1.445.g3cdd5d1