resolved: properly handles RRs in domains beginning in an asterisk label

Properly handle RRs that begin with an asterisk label. These are the unexpanded forms of wildcard domains and appear in
NSEC RRs for example. We need to make sure we handle the signatures of these RRs properly, since they mostly are
considered normal RRs, except that the RRSIG labels counter is one off for them, as the asterisk label is always
excluded of the signature.

src/resolve/resolved-dns-dnssec.c

@@ -548,7 +548,18 @@ int dnssec_verify_rrset(
         r = dns_name_suffix(DNS_RESOURCE_KEY_NAME(key), rrsig->rrsig.labels, &source);
         if (r < 0)
                 return r;
-        wildcard = r > 0;
+        if (r == 1) {
+                /* If we stripped a single label, then let's see if that maybe was "*". If so, we are not really
+                 * synthesized from a wildcard, we are the wildcard itself. Treat that like a normal name. */
+                r = dns_name_startswith(DNS_RESOURCE_KEY_NAME(key), "*");
+                if (r < 0)
+                        return r;
+                if (r > 0)
+                        source = DNS_RESOURCE_KEY_NAME(key);
+
+                wildcard = r == 0;
+        } else
+                wildcard = r > 0;
 
         /* Collect all relevant RRs in a single array, so that we can look at the RRset */
         list = newa(DnsResourceRecord *, dns_answer_size(a));