Add comment about cookie sizes

(cherry picked from commit 304df539919beb5da6d33d8690b5e588476308d8)

diff --git a/lib/dns/rdata/generic/opt_41.c b/lib/dns/rdata/generic/opt_41.c
index 36ae6abe76171db7cf0d556e9445a17a84bf7d6b..40fcbe7885689f91eb14900eddcbbacedc517e81 100644 (file)
--- a/lib/dns/rdata/generic/opt_41.c
+++ b/lib/dns/rdata/generic/opt_41.c
@@ -193,6 +193,10 @@ fromwire_opt(ARGS_FROMWIRE) {
                        isc_region_consume(&sregion, length);
                        break;
                case DNS_OPT_COOKIE:
+                       /*
+                        * Client cookie alone has length 8.
+                        * Client + server cookie is 8 + [8..32].
+                        */
                        if (length != 8 && (length < 16 || length > 40)) {
                                return (DNS_R_OPTERR);
                        }