RFC 9660 The DNS Zone Version (ZONEVERSION) Option

edns.c

@@ -70,6 +70,7 @@ edns_init_record(edns_record_type *edns)
 	edns->opt_reserved_space = 0;
 	edns->dnssec_ok = 0;
 	edns->nsid = 0;
+	edns->zoneversion = 0;
 	edns->cookie_status = COOKIE_NOT_PRESENT;
 	edns->cookie_len = 0;
 	edns->ede = -1; /* -1 means no Extended DNS Error */
@@ -116,6 +117,11 @@ edns_handle_option(uint16_t optcode, uint16_t optlen, buffer_type* packet,
 			buffer_skip(packet, optlen);
 		}
 		break;
+	case ZONEVERSION_CODE:
+		edns->zoneversion = 1;
+		if(optlen > 0)
+			return 0;
+		break;
 	default:
 		buffer_skip(packet, optlen);
 		break;

edns.h

@@ -20,6 +20,7 @@ struct query;
 #define NSID_CODE       3               /* nsid option code */
 #define COOKIE_CODE    10               /* COOKIE option code */
 #define EDE_CODE       15               /* Extended DNS Errors option code */
+#define ZONEVERSION_CODE 19             /* ZONEVERSION option code */
 #define DNSSEC_OK_MASK  0x8000U         /* do bit mask */
 
 struct edns_data
@@ -59,6 +60,7 @@ struct edns_record
 	size_t		   opt_reserved_space;
 	int                dnssec_ok;
 	int                nsid;
+	int                zoneversion;
 	cookie_status_type cookie_status;
 	size_t             cookie_len;
 	uint8_t            cookie[40];

query.c

@@ -1780,6 +1780,17 @@ query_add_optional(query_type *q, nsd_type *nsd, uint32_t *now_p)
 				6 + ( q->edns.ede_text_len
 			            ? q->edns.ede_text_len : 0);
 
+		if(q->edns.zoneversion
+		&& q->zone
+		&& q->zone->soa_rrset
+		&& q->zone->soa_rrset->rrs
+		&& q->zone->soa_rrset->rrs->rdata_count >= 3)
+			q->edns.opt_reserved_space += sizeof(uint16_t)
+			                           +  sizeof(uint16_t)
+			                           +  sizeof(uint8_t)
+			                           +  sizeof(uint8_t)
+			                           +  sizeof(uint32_t);
+
 		if(q->edns.opt_reserved_space == 0 || !buffer_available(
 			q->packet, 2+q->edns.opt_reserved_space)) {
 			/* fill with NULLs */
@@ -1794,6 +1805,23 @@ query_add_optional(query_type *q, nsd_type *nsd, uint32_t *now_p)
 				/* nsid payload */
 				buffer_write(q->packet, nsd->nsid, nsd->nsid_len);
 			}
+			if(q->edns.zoneversion
+			&& q->zone
+			&& q->zone->soa_rrset
+			&& q->zone->soa_rrset->rrs
+			&& q->zone->soa_rrset->rrs->rdata_count >= 3) {
+				buffer_write_u16(q->packet, ZONEVERSION_CODE);
+				buffer_write_u16( q->packet
+				                , sizeof(uint8_t)
+						+ sizeof(uint8_t)
+						+ sizeof(uint32_t));
+				buffer_write_u8(q->packet,
+				    domain_dname(q->zone->apex)->label_count - 1);
+				buffer_write_u8(q->packet, 0);
+				buffer_write_u32(q->packet,
+				    read_uint32(rdata_atom_data(
+				    q->zone->soa_rrset->rrs->rdatas[2])));
+			}
 			if(q->edns.cookie_status != COOKIE_NOT_PRESENT) {
 				/* cookie opt header */
 				buffer_write(q->packet, edns->cookie, OPT_HDR);