rec: a single NSEC3 record covering everything is a special case

Fixes #13542

(cherry picked from commit 257b23b4f55031a94b04c472489c3806ab57a244)

diff --git a/pdns/recursordist/aggressive_nsec.cc b/pdns/recursordist/aggressive_nsec.cc
index 16ea10e0112d293fe0c2fba23ce19253a60459cb..ce2336219889ce5bff171cf3f34308f8231a461b 100644 (file)
--- a/pdns/recursordist/aggressive_nsec.cc
+++ b/pdns/recursordist/aggressive_nsec.cc
@@ -262,6 +262,10 @@ static bool commonPrefixIsLong(const string& one, const string& two, size_t boun
 bool AggressiveNSECCache::isSmallCoveringNSEC3(const DNSName& owner, const std::string& nextHash)
 {
   std::string ownerHash(fromBase32Hex(owner.getRawLabel(0)));
+  // Special case: empty zone, so the single NSEC3 covers everything. Prefix is long but we still want it cached.
+  if (ownerHash == nextHash) {
+    return false;
+  }
   return commonPrefixIsLong(ownerHash, nextHash, AggressiveNSECCache::s_maxNSEC3CommonPrefix);
 }