util: Add memcmp_const_time()

[amitay/samba.git] / lib / util / util_str.c

diff --git a/lib/util/util_str.c b/lib/util/util_str.c
index 673fbc7c6b5ebac23a88020eb0510afb77b1e0cd..c7d91ca3744b63aa80a13c55b72e1e2296b82f6f 100644 (file)
--- a/lib/util/util_str.c
+++ b/lib/util/util_str.c
@@ -333,3 +333,15 @@ _PUBLIC_ size_t utf16_len_n(const void *src, size_t n)
 
        return len;
 }
+
+_PUBLIC_ int memcmp_const_time(const void *s1, const void *s2, size_t n)
+{
+       const uint8_t *p1 = s1, *p2 = s2;
+       size_t i, sum = 0;
+
+       for (i = 0; i < n; i++) {
+               sum |= (p1[i] ^ p2[i]);
+       }
+
+       return sum != 0;
+}