[radvd-devel-l] RDNSS Option

Pekka Savola pekkas at netcore.fi
Tue Mar 7 07:58:04 EST 2006



On Mon, 6 Mar 2006, Mickaël Guérin wrote:
> I've written a page to summarize what has been done (still under
> construction) : http://withinthebox.net/ipv6/
> We have developped a GNU/Linux client but the current version is still
> 'dirty'.

A few comments on the patch on the web page, without compile or 
run-testing at this point:

Generic comments:
  - at some point, radvdump parser should be included
  - you don't seem to implement Lifetime bounding
    between {Min,Max}RtrAdvInterval.  The default value for
    AdvRDNSSLifetime should maybe be taken from there.
  - I hope the draft gets approved in the IETF before we ship the code,
    but you never know how long it takes...

A few specific ones:

+/* pref/flag/reserved field : yyyyx00000000000 (big endian) - 00000000yyyyx000 (little indian); where yyyy = pref, x = flag */

==> does this work OK in a little-endian machine if one of the 8 
high-order zero bits would, at some later date, get used?  Should you 
use '0xf' instead of '0xff' ?

+			rdnss_init_defaults(rdnss, iface);
+			rdnss->AdvRDNSSNumber = 1;

==> is there a reason for overwriting the number of RDNSS's?

+	rdnss->AdvSFlag = DFLT_AdvSFlag;

==> AdvSFlag needs to be better named, as it's specific to RDNSS, 
maybe AdvRDNSSSFlag or AdvRDNSSOpenFlag ?  Especially in the actual 
configuration syntax-- "AdvS" isn't good, maybe "AdvRDNSSOpen" or 

+RDNSS (Recursive DNS server) definitions are of the form:
+.BR "rdnss " "ip " {
+	list of rdnss specific options
+.B };

==> If I understand correctly, the syntax is:

RDNSS ip1 [ip2] [ip3] {

or something?  And there can be only one RDNSS definition under
an interface's configuration.   Is this true?

+.BR "AdvS " on | off;
+"Service Open" flag. When set, it indicates that RDNSS can be 
available for IPv6 hosts which are located in the different network 
with the RDNSS.
+Default: on

==> the default value should be disabled.

+# NOTE: This feature is still a draft has no IANA number type for the 
+	rdnss 2001::1

==> the option name should probably be in upper-case, should use 
addresses under 2001:db8::/32, and should include multiple servers.

+		// TODO : regrouper en fonction de pref lifetime et S, au plus 3 RDNSS

==> excuse my french... :)

+J. Jeong, L. Beloeil, and S. Madanapalli, "IPv6 Router Advertisement 
Option for DNS Configuration", Draft ietf.

==> please add the draft name, version, etc.

Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

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