1 files changed, 83 insertions, 0 deletions
diff --git a/lib/dnssec/nsec3.h b/lib/dnssec/nsec3.h
new file mode 100644
index 0000000..eb0bd39
--- /dev/null
+++ b/lib/dnssec/nsec3.h
@@ -0,0 +1,83 @@
+/*  Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <libknot/packet/pkt.h>
+
+/** High numbers in NSEC3 iterations don't really help security
+ *
+ * ...so we avoid doing all the work.  The value is a current compromise;
+ * zones shooting over get downgraded to insecure status.
+ *
+ * Original restriction wasn't that strict:
+   https://datatracker.ietf.org/doc/html/rfc5155#section-10.3
+ * but there is discussion about officially lowering the limits:
+   https://tools.ietf.org/id/draft-hardaker-dnsop-nsec3-guidance-02.html#section-2.3
+ */
+#define KR_NSEC3_MAX_ITERATIONS 150
+
+/**
+ * Name error response check (RFC5155 7.2.2).
+ * @note No RRSIGs are validated.
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param sname      Name to be checked.
+ * @return           0 or error code.
+ */
+int kr_nsec3_name_error_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                       const knot_dname_t *sname);
+
+/**
+ * Wildcard answer response check (RFC5155 7.2.6).
+ * @param pkt          Packet structure to be processed.
+ * @param section_id   Packet section to be processed.
+ * @param sname        Name to be checked.
+ * @param trim_to_next Number of labels to remove to obtain next closer name.
+ * @return             0 or error code:
+ *                     KNOT_ERANGE - NSEC3 RR that covers a wildcard
+ *                     has been found, but has opt-out flag set;
+ *                     otherwise - error.
+ * Records over KR_NSEC3_MAX_ITERATIONS are skipped, so you probably get kr_error(ENOENT).
+ */
+int kr_nsec3_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                            const knot_dname_t *sname, int trim_to_next);
+
+/**
+ * Authenticated denial of existence according to RFC5155 8.5 and 8.7.
+ * @note No RRSIGs are validated.
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param sname      Queried domain name.
+ * @param stype      Queried type.
+ * @return           0 or error code:
+ *                   DNSSEC_NOT_FOUND - neither ds nor nsec records
+ *                   were not found.
+ *                   KNOT_ERANGE - denial of existence can't be proven
+ *                   due to opt-out, otherwise - bogus.
+ */
+int kr_nsec3_no_data(const knot_pkt_t *pkt, knot_section_t section_id,
+                     const knot_dname_t *sname, uint16_t stype);
+
+/**
+ * Referral to unsigned subzone check (RFC5155 8.9).
+ * @note 	     No RRSIGs are validated.
+ * @param pkt        Packet structure to be processed.
+ * @return           0 or error code:
+ *                   KNOT_ERANGE - denial of existence can't be proven
+ *                   due to opt-out.
+ *                   EEXIST - ds record was found.
+ *                   EINVAL - bogus.
+ */
+int kr_nsec3_ref_to_unsigned(const knot_pkt_t *pkt);
+
+/**
+ * Checks whether supplied NSEC3 RR matches the supplied name and NS type.
+ * @param nsec3 NSEC3 RR.
+ * @param name  Name to be checked.
+ * @param type  Type to be checked.  Only use with NS!  TODO
+ * @return      0 or error code.
+ */
+int kr_nsec3_matches_name_and_type(const knot_rrset_t *nsec3,
+				   const knot_dname_t *name, uint16_t type);