cache: avoid some crashes

It's actually possible to start queries without any cache open,
e.g. add `resolve('.', kres.type.DNSKEY)` into your configuration.
If that happens, avoid the cache module dereferencing a NULL pointer.

diff --git a/lib/cache/api.c b/lib/cache/api.c
index d6414ebd2b118e980fc98e7c164c5b50ee6f6446..c0591d653ed4853af9123129c74cbf1a6dc5d533 100644 (file)
--- a/lib/cache/api.c
+++ b/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;
        }