From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Thu, 30 Jul 2026 12:24:21 +0000 (+0200)
Subject: lib/rules: log more info for a MDB_BAD_VALSIZE case
X-Git-Tag: v6.4.2~2^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1fd85ffd3ecedda7ecd08e245a857bfe55a64227;p=thirdparty%2Fknot-resolver.git

lib/rules: log more info for a MDB_BAD_VALSIZE case

Issue 956: it's not difficult to run into this limit, e.g. by using
blocking style with hosts-like files pointing names to 127.0.0.1.
Now it additionally explains a little, e.g.:
  [rules ] records too big (512 B) for 1.0.0.127.in-addr.arpa. PTR
---

diff --git a/lib/rules/api.c b/lib/rules/api.c
index 679fee637..7a57aad9d 100644
--- a/lib/rules/api.c
+++ b/lib/rules/api.c
@@ -8,6 +8,7 @@
 #include "lib/cache/cdb_lmdb.h"
 
 #include <stdlib.h>
+#include <lmdb.h>
 
 
 struct kr_rules *the_rules = NULL;
@@ -635,8 +636,15 @@ int local_data_ins(knot_db_val_t key, const knot_rrset_t *rrs, const knot_rdatas
 
 	knot_db_val_t val = { .data = buf, .len = val_len };
 	int ret = ruledb_op(write, &key, &val, 1); // TODO: overwriting on ==tags?
-	// ENOSPC seems to be the only expectable error.
-	kr_assert(ret == 0 || ret == kr_error(ENOSPC));
+	if (unlikely(ret == MDB_BAD_VALSIZE)) { // yeah, leaking implementation details
+		KR_DNAME_GET_STR(owner_str, rrs->owner);
+		KR_RRTYPE_GET_STR(type_str, rrs->type);
+		kr_log_error(RULES, "records too big (%d B) for %s %s\n",
+				val_len, owner_str, type_str);
+	} else {
+		// ENOSPC seems to be the only other expectable error.
+		kr_assert(ret == 0 || ret == kr_error(ENOSPC));
+	}
 
 	if (ret || rrs->type != KNOT_RRTYPE_DNAME)
 		return ret;