lib/util: Change function to mem_equal_const_time()

Since memcmp_const_time() doesn't act as an exact replacement for
memcmp(), and its return value is only ever compared with zero, simplify
it and emphasize the intention of checking equality by returning a bool
instead.

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

3 files changed, 7 insertions, 7 deletions

diff --git a/lib/util/data_blob.c b/lib/util/data_blob.c
index 3dccdc1c58a..677f7c19211 100644
--- a/lib/util/data_blob.c
+++ b/lib/util/data_blob.c
@@ -136,7 +136,7 @@ contents of either blob.
 **/
 _PUBLIC_ bool data_blob_equal_const_time(const DATA_BLOB *d1, const DATA_BLOB *d2)
 {
-	int ret;
+	bool ret;
 	if (d1->data == NULL && d2->data != NULL) {
 		return false;
 	}
@@ -149,8 +149,8 @@ _PUBLIC_ bool data_blob_equal_const_time(const DATA_BLOB *d1, const DATA_BLOB *d
 	if (d1->data == d2->data) {
 		return true;
 	}
-	ret = memcmp_const_time(d1->data, d2->data, d1->length);
-	return ret == 0;
+	ret = mem_equal_const_time(d1->data, d2->data, d1->length);
+	return ret;
 }
 
 /**
diff --git a/lib/util/samba_util.h b/lib/util/samba_util.h
index ca185909997..ac185cc06c5 100644
--- a/lib/util/samba_util.h
+++ b/lib/util/samba_util.h
@@ -321,9 +321,9 @@ _PUBLIC_ bool conv_str_u64(const char * str, uint64_t * val);
  *
  * @param[in]  n   The length of the memory to comapre.
  *
- * @return 0 when the memory regions are equal, 0 if not.
+ * @return true when the memory regions are equal, false if not.
  */
-_PUBLIC_ int memcmp_const_time(const void *s1, const void *s2, size_t n);
+_PUBLIC_ bool mem_equal_const_time(const void *s1, const void *s2, size_t n);
 
 /**
  * @brief Build up a string buffer, handle allocation failure
diff --git a/lib/util/util.c b/lib/util/util.c
index 1cf3ff4e525..f039452976f 100644
--- a/lib/util/util.c
+++ b/lib/util/util.c
@@ -1097,7 +1097,7 @@ _PUBLIC_ size_t ascii_len_n(const char *src, size_t n)
 	return len;
 }
 
-_PUBLIC_ int memcmp_const_time(const void *s1, const void *s2, size_t n)
+_PUBLIC_ bool mem_equal_const_time(const void *s1, const void *s2, size_t n)
 {
 	const uint8_t *p1 = s1, *p2 = s2;
 	size_t i, sum = 0;
@@ -1106,7 +1106,7 @@ _PUBLIC_ int memcmp_const_time(const void *s1, const void *s2, size_t n)
 		sum |= (p1[i] ^ p2[i]);
 	}
 
-	return sum != 0;
+	return sum == 0;
 }
 
 struct anonymous_shared_header {