cache: turn off QNAME minimization in deeper zones

This matches behavior of kresd <= 1.5.3 - check_empty_nonterms(...)
Currently the iterator is unable to do QNAME minimization in deeper
zones, so switching it off is the only thing to do for now :-/
Fixes https://gitlab.labs.nic.cz/knot/knot-resolver/issues/316

diff --git a/NEWS b/NEWS
index 9cdb5f126caa20508a0bb68c52de604d463f7dd0..3bfea2e7e85fb8e13e8e0e0dc29d6964ec642662 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -3,8 +3,8 @@ Knot Resolver 2.x.y (2018-02-zz)
 
 Bugfixes
 --------
-- when iterating, avoid unnecessary queries for NS in insecure parent.
-  This problem worsened in 2.0.0. (#246)
+- when iterating, avoid unnecessary queries for NS in insecure parent
+  or in deeper zones.  This problem worsened in 2.0.0. (#246, #316)
 
 
 Knot Resolver 2.1.0 (2018-02-16)

diff --git a/lib/cache/api.c b/lib/cache/api.c
index e459adc42131389b08bd60b0a6f176b604de12de..fe33a78ab6c4910e0e9744caee301bad5e24c42d 100644 (file)
--- a/lib/cache/api.c
+++ b/lib/cache/api.c
@@ -292,7 +292,7 @@ static knot_db_val_t key_exact_type(struct key *k, uint16_t type)
 static uint8_t get_lowest_rank(const struct kr_request *req, const struct kr_query *qry);
 static int found_exact_hit(kr_layer_t *ctx, knot_pkt_t *pkt, knot_db_val_t val,
                           uint8_t lowest_rank);
-static knot_db_val_t closest_NS(kr_layer_t *ctx, struct key *k);
+static knot_db_val_t closest_NS(kr_layer_t *ctx, struct key *k, knot_pkt_t *pkt);
 static int answer_simple_hit(kr_layer_t *ctx, knot_pkt_t *pkt, uint16_t type,
                const struct entry_h *eh, const void *eh_bound, uint32_t new_ttl);
 static int cache_peek_real(kr_layer_t *ctx, knot_pkt_t *pkt);
@@ -373,7 +373,7 @@ static int cache_peek_real(kr_layer_t *ctx, knot_pkt_t *pkt)
        /** 1b. otherwise, find the longest prefix NS/xNAME (with OK time+rank). [...] */
        k->zname = qry->sname;
        kr_dname_lf(k->buf, k->zname, false); /* LATER(optim.): probably remove */
-       const knot_db_val_t val_cut = closest_NS(ctx, k);
+       const knot_db_val_t val_cut = closest_NS(ctx, k, pkt);
        if (!val_cut.data) {
                VERBOSE_MSG(qry, "=> not even root NS in cache, but let's try NSEC\n");
        }
@@ -999,7 +999,7 @@ int kr_cache_peek_exact(struct kr_cache *cache, const knot_dname_t *name, uint16
  *
  * \param exact_match Whether exact match is considered special.
  */
-static knot_db_val_t closest_NS(kr_layer_t *ctx, struct key *k)
+static knot_db_val_t closest_NS(kr_layer_t *ctx, struct key *k, knot_pkt_t *pkt)
 {
        static const knot_db_val_t VAL_EMPTY = { NULL, 0 };
        struct kr_request *req = ctx->req;
@@ -1071,22 +1071,33 @@ static knot_db_val_t closest_NS(kr_layer_t *ctx, struct key *k)
                                goto next_label;
                        }
                        int32_t new_ttl = get_new_ttl(eh, qry, k->zname, type);
-                       if (new_ttl < 0
-                           /* Not interested in negative or bogus. */
-                           || eh->is_packet
-                           /* For NS any kr_rank is accepted,
-                            * as insecure or even nonauth is OK */
-                           || (type != KNOT_RRTYPE_NS && eh->rank < rank_min)) {
-
+                       bool skip = new_ttl < 0
+                               /* For NS any kr_rank is accepted,
+                                * as insecure or even nonauth is OK */
+                               || (type != KNOT_RRTYPE_NS && eh->rank < rank_min);
+                       bool log_no_min = false;
+                       if (!skip && eh->is_packet) {
+                               /* Not interested in negative answers, but we want
+                                * to optimize the following iteration, if any.
+                                * LATER: improve whole QNAME minimization. */
+                               skip = true;
+                               if (type == KNOT_RRTYPE_NS && !qry->flags.NO_MINIMIZE) {
+                                       qry->flags.NO_MINIMIZE = true;
+                                       kr_make_query(qry, pkt);
+                                       log_no_min = true;
+                               }
+                       }
+                       if (skip) {
                                WITH_VERBOSE(qry) {
                                        auto_free char *type_str =
                                                kr_rrtype_text(type);
                                        const char *packet_str =
                                                eh->is_packet ? "packet" : "RR";
                                        VERBOSE_MSG(qry, "=> skipping unfit %s %s: "
-                                               "rank 0%.2o, new TTL %d\n",
+                                               "rank 0%.2o, new TTL %d%s\n",
                                                type_str, packet_str,
-                                               eh->rank, new_ttl);
+                                               eh->rank, new_ttl,
+                                               log_no_min ? " (NO_MINIMIZE->true)" : "");
                                }
                                continue;
                        }