packet: add ldns_pkt_edns_unassigned and ldns_pkt_set_edns_unassigned

ldns/packet.h

@@ -706,6 +706,18 @@ bool ldns_pkt_edns_do(const ldns_pkt *packet);
  */
 void ldns_pkt_set_edns_do(ldns_pkt *packet, bool value);
 
+/**
+ * return the packet's EDNS header bits that are unassigned.
+ */
+uint16_t ldns_pkt_edns_unassigned(const ldns_pkt *packet);
+
+/**
+ * Set the packet's EDNS header bits that are unassigned.
+ * \param[in] packet the packet
+ * \param[in] value the value
+ */
+void ldns_pkt_set_edns_unassigned(ldns_pkt *packet, uint16_t value);
+
 /**
  * returns true if this packet needs and EDNS rr to be sent.
  * At the moment the only reason is an expected packet

packet.c

@@ -26,6 +26,7 @@
  */
 
 #define LDNS_EDNS_MASK_DO_BIT 0x8000
+#define LDNS_EDNS_MASK_UNASSIGNED (0xFFFF & ~LDNS_EDNS_MASK_DO_BIT)
 
 /* TODO defines for 3600 */
 /* convert to and from numerical flag values */
@@ -242,6 +243,19 @@ ldns_pkt_set_edns_do(ldns_pkt *packet, bool value)
 	}
 }
 
+uint16_t
+ldns_pkt_edns_unassigned(const ldns_pkt *packet)
+{
+	return (packet->_edns_z & LDNS_EDNS_MASK_UNASSIGNED);
+}
+
+void
+ldns_pkt_set_edns_unassigned(ldns_pkt *packet, uint16_t value)
+{
+	packet->_edns_z = (packet->_edns_z & ~LDNS_EDNS_MASK_UNASSIGNED)
+			| (value & LDNS_EDNS_MASK_UNASSIGNED);
+}
+
 ldns_rdf *
 ldns_pkt_edns_data(const ldns_pkt *packet)
 {