hashmap: hash_funcs - make inputs unambiguous

Make sure all variable-length inputs are properly terminated or that
their length is encoded in some way. This avoids ambiguity of
adjacent inputs.

E.g., in case of a hash function taking two strings, compressing "ab"
followed by "c" is now distinct from "a" followed by "bc".

1 files changed, 6 insertions, 0 deletions

diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c
index 1517443736..5680f01bd9 100644
--- a/src/shared/dns-domain.c
+++ b/src/shared/dns-domain.c
@@ -399,11 +399,17 @@ void dns_name_hash_func(const void *s, struct siphash *state) {
                 if (k > 0)
                         r = k;
 
+                if (r == 0)
+                        break;
+
                 label[r] = 0;
                 ascii_strlower(label);
 
                 string_hash_func(label, state);
         }
+
+        /* enforce that all names are terminated by the empty label */
+        string_hash_func("", state);
 }
 
 int dns_name_compare_func(const void *a, const void *b) {