Merge !681: various nitpicks, see commits for details

lib/cache/api.c

@@ -315,7 +315,8 @@ int cache_peek(kr_layer_t *ctx, knot_pkt_t *pkt)
 	struct kr_query *qry = req->current_query;
 	/* We first check various exit-conditions and then call the _real function. */
 
-	if (ctx->state & (KR_STATE_FAIL|KR_STATE_DONE) || qry->flags.NO_CACHE
+	if (!kr_cache_is_open(&req->ctx->cache)
+	    || ctx->state & (KR_STATE_FAIL|KR_STATE_DONE) || qry->flags.NO_CACHE
 	    || (qry->flags.CACHE_TRIED && !qry->stale_cb)
 	    || !check_rrtype(qry->stype, qry) /* LATER: some other behavior for some of these? */
 	    || qry->sclass != KNOT_CLASS_IN) {
@@ -358,7 +359,8 @@ int cache_stash(kr_layer_t *ctx, knot_pkt_t *pkt)
 
 	/* Note: we cache even in KR_STATE_FAIL.  For example,
 	 * BOGUS answer can go to +cd cache even without +cd request. */
-	if (!qry || qry->flags.CACHED || !check_rrtype(knot_pkt_qtype(pkt), qry)
+	if (!kr_cache_is_open(cache) || !qry
+	    || qry->flags.CACHED || !check_rrtype(knot_pkt_qtype(pkt), qry)
 	    || qry->sclass != KNOT_CLASS_IN) {
 		return ctx->state;
 	}

lib/generic/trie.c

@@ -438,8 +438,8 @@ typedef struct trie_it {
 	node_t* *stack; /*!< The stack; malloc is used directly instead of mm. */
 	uint32_t len;   /*!< Current length of the stack. */
 	uint32_t alen;  /*!< Allocated/available length of the stack. */
-	/*! \brief Initial storage for \a stack; it should fit in most use cases. */
-	node_t* stack_init[2000 / sizeof(node_t *)];
+	/*! \brief Initial storage for \a stack; it should fit in many use cases. */
+	node_t* stack_init[60];
 } nstack_t;
 
 /*! \brief Create a node stack containing just the root (or empty). */

lib/generic/trie.h

@@ -121,6 +121,9 @@ trie_it_t* trie_it_begin(trie_t *tbl);
  *
  * Iteration is in ascending lexicographical order.
  * In particular, the empty string would be considered as the very first.
+ *
+ * \note You may not use this function if the trie's key-set has been modified
+ * during the lifetime of the iterator (modifying values only is OK).
  */
 KR_EXPORT
 void trie_it_next(trie_it_t *it);

modules/rfc7706.rst

-Root on lookback (RFC 7706)
+Root on loopback (RFC 7706)
 ---------------------------
 Knot Resolver developers decided that pure implementation of :rfc:`7706` is a bad idea so it is not implemented in the form envisioned by the RFC. You can get the very similar effect without its downsides by combining :ref:`prefill <mod-prefill>` and :ref:`serve_stale <mod-serve_stale>` modules with Aggressive Use of DNSSEC-Validated Cache (:rfc:`8198`) behavior which is enabled automatically together with DNSSEC validation.