From: Karel Slany <karel.slany@nic.cz>
Date: Wed, 13 Jul 2016 08:50:11 +0000 (+0200)
Subject: Added a commentary.
X-Git-Tag: v1.1.0~2^2~66
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=5d7d52d4325849711bb82d5d2a7dcf8748fc4b23;p=thirdparty%2Fknot-resolver.git

Added a commentary.
---

diff --git a/lib/cookies/helper.c b/lib/cookies/helper.c
index 5e0704049..161b56c6a 100644
--- a/lib/cookies/helper.c
+++ b/lib/cookies/helper.c
@@ -222,6 +222,15 @@ int kr_answer_write_cookie(const struct knot_sc_private *srvr_data,
 
 int kr_pkt_set_ext_rcode(knot_pkt_t *pkt, uint16_t whole_rcode)
 {
+	/*
+	 * RFC6891 6.1.3 -- extended RCODE forms the upper 8 bits of whole
+	 * 12-bit RCODE (together with the 4 bits of 'normal' RCODE).
+	 *
+	 * | 11 10 09 08 07 06 05 04 | 03 02 01 00 |
+	 * |          12-bit whole RCODE           |
+	 * |   8-bit extended RCODE  | 4-bit RCODE |
+	 */
+
 	if (!pkt || !knot_pkt_has_edns(pkt)) {
 		return kr_error(EINVAL);
 	}