nameserver: disable multi-message answers thru XDP...

...until out-buffers are implemented
...to avoid XDP buffers overrun on large answer

src/knot/nameserver/axfr.c

@@ -191,6 +191,9 @@ int axfr_process_query(knot_pkt_t *pkt, knotd_qdata_t *qdata)
 			            knot_strerror(ret));
 			return KNOT_STATE_FAIL;
 		}
+	} else if (qdata->params->xdp_msg != NULL) {
+		qdata->rcode = KNOT_RCODE_SERVFAIL;
+		return KNOT_STATE_FAIL;
 	}
 
 	/* Reserve space for TSIG. */

src/knot/nameserver/ixfr.c

@@ -283,6 +283,9 @@ int ixfr_process_query(knot_pkt_t *pkt, knotd_qdata_t *qdata)
 			            knot_strerror(ret));
 			return KNOT_STATE_FAIL;
 		}
+	} else if (qdata->params->xdp_msg != NULL) {
+		qdata->rcode = KNOT_RCODE_SERVFAIL;
+		return KNOT_STATE_FAIL;
 	}
 
 	/* Reserve space for TSIG. */