anastasis

commit 22089cd6a77323e95733da90d6e515e26a61cba1
parent ad00e002917b616326a198e2516d5dee2e6b4a03
Author: Christian Grothoff <christian@grothoff.org>
Date:   Wed, 29 Jul 2026 18:43:20 +0200

only let the newest challenge code be answered

Diffstat:
M
src/stasis/do_verify_challenge_code.c
 | 
9
++++++++-

1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/stasis/do_verify_challenge_code.c b/src/stasis/do_verify_challenge_code.c
@@ -179,6 +179,11 @@ ANASTASIS_DB_do_verify_challenge_code (
            " WHERE truth_uuid=$1"
            "   AND code=$2"
            "   AND retry_counter != 0;");
+  /* Only the newest code is answerable.  A truth can have several unexpired
+     codes at once, and without the LIMIT every one of them that does not
+     match burns a retry -- so a single wrong guess could exhaust the counter,
+     and even a correct answer cost retries for its siblings.  This matches
+     what insert_challenge_code.c already assumes when it issues a code. */
   PREPARE ("do_verify_challenge_code_select",
            "SELECT "
            " code"
@@ -186,7 +191,9 @@ ANASTASIS_DB_do_verify_challenge_code (
            " FROM anastasis_challengecode"
            " WHERE truth_uuid=$1"
            "   AND expiration_date > $2"
-           "   AND retry_counter != 0;");
+           "   AND retry_counter != 0"
+           " ORDER BY creation_date DESC"
+           " LIMIT 1;");
   qs = GNUNET_PQ_eval_prepared_multi_select (pg->conn,
                                              "do_verify_challenge_code_select",
                                              params,