resolved: when validating an RRset, store information about the synthesizing source and zone in each RR

Having this information available is useful when we need to check whether various RRs are suitable for proofs. This
information is stored in the RRs as number of labels to skip from the beginning of the owner name to reach the
synthesizing source/signer. Simple accessor calls are then added to retrieve the signer/source from the RR using this
information.

This also moves validation of a a number of RRSIG parameters into a new call dnssec_rrsig_prepare() that as side-effect
initializes the two numeric values.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/resolve/resolved-dns-rr.h b/src/resolve/resolved-dns-rr.h
index fe29a41566..8e7bfaa7c7 100644
--- a/src/resolve/resolved-dns-rr.h
+++ b/src/resolve/resolved-dns-rr.h
@@ -108,14 +108,24 @@ struct DnsTxtItem {
 struct DnsResourceRecord {
         unsigned n_ref;
         DnsResourceKey *key;
+
         char *to_string;
+
         uint32_t ttl;
         usec_t expiry; /* RRSIG signature expiry */
+
+        /* How many labels to strip to determine "signer" of the RRSIG (aka, the zone). -1 if not signed. */
+        unsigned n_skip_labels_signer;
+        /* How many labels to strip to determine "synthesizing source" of this RR, i.e. the wildcard's immediate parent. -1 if not signed. */
+        unsigned n_skip_labels_source;
+
         bool unparseable:1;
+
         bool wire_format_canonical:1;
         void *wire_format;
         size_t wire_format_size;
         size_t wire_format_rdata_offset;
+
         union {
                 struct {
                         void *data;
@@ -296,6 +306,10 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(DnsResourceRecord*, dns_resource_record_unref);
 
 int dns_resource_record_to_wire_format(DnsResourceRecord *rr, bool canonical);
 
+int dns_resource_record_signer(DnsResourceRecord *rr, const char **ret);
+int dns_resource_record_source(DnsResourceRecord *rr, const char **ret);
+int dns_resource_record_is_signer(DnsResourceRecord *rr, const char *zone);
+
 DnsTxtItem *dns_txt_item_free_all(DnsTxtItem *i);
 bool dns_txt_item_equal(DnsTxtItem *a, DnsTxtItem *b);