From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Wed, 10 Oct 2018 15:00:07 +0000 (+0200)
Subject: cache: avoid some crashes
X-Git-Tag: v3.1.0~8^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c22bff61cf3e2682a2ca861072877a3c53e12d45;p=thirdparty%2Fknot-resolver.git

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 d6414ebd2..c0591d653 100644
--- 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;
 	}