validator: lower the NSEC3 iteration limit (150 -> 50)

Also done by BIND9 >= 9.19.19:
https://gitlab.isc.org/isc-projects/bind9/-/merge_requests/8515

The latest real-life measurements show that values above 50 are rare:
https://chat.dns-oarc.net/community/pl/aadp9wwrp7g7ux1b8chbzebmze

diff --git a/lib/dnssec/nsec3.h b/lib/dnssec/nsec3.h
index eb0bd39781925d723316df575da105fc17c59364..723dc4a1379ce7634988bd1d0cb3ea658426cbc3 100644 (file)
--- a/lib/dnssec/nsec3.h
+++ b/lib/dnssec/nsec3.h
@@ -11,12 +11,9 @@
  * ...so we avoid doing all the work.  The value is a current compromise;
  * zones shooting over get downgraded to insecure status.
  *
- * Original restriction wasn't that strict:
-   https://datatracker.ietf.org/doc/html/rfc5155#section-10.3
- * but there is discussion about officially lowering the limits:
-   https://tools.ietf.org/id/draft-hardaker-dnsop-nsec3-guidance-02.html#section-2.3
+   https://datatracker.ietf.org/doc/html/rfc9276#name-recommendation-for-validati
  */
-#define KR_NSEC3_MAX_ITERATIONS 150
+#define KR_NSEC3_MAX_ITERATIONS 50
 
 /**
  * Name error response check (RFC5155 7.2.2).