+static bool dns_transaction_dnssec_supported(DnsTransaction *t) {
+ assert(t);
+
+ /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
+ * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
+
+ if (t->scope->protocol != DNS_PROTOCOL_DNS)
+ return false;
+
+ /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
+ * be supported, hence return true. */
+ if (!t->server)
+ return true;
+
+ if (t->current_features < DNS_SERVER_FEATURE_LEVEL_DO)
+ return false;
+
+ return dns_server_dnssec_supported(t->server);
+}
+
+static bool dns_transaction_dnssec_supported_full(DnsTransaction *t) {
+ DnsTransaction *dt;
+ Iterator i;
+
+ assert(t);
+
+ /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
+
+ if (!dns_transaction_dnssec_supported(t))
+ return false;
+
+ SET_FOREACH(dt, t->dnssec_transactions, i)
+ if (!dns_transaction_dnssec_supported(dt))
+ return false;
+
+ return true;
+}
+