[RFC] resolvconf(8) interface id

[Hiroki Sato]

"Bjoern A. Zeeb" <bzeeb-lists at lists.zabbadoz.net> wrote
  in <6FE95AC6-CCB2-45B0-8347-AB31283EE144 at lists.zabbadoz.net>:

bz> I am not entirely sure I like "slaac" or "dhcp4".  I wonder if progname
bz> would be sufficient in call cases either (I could well see a "dhclient"
bz> or another "fooapp" that can handle both v4 and v6) but in that case it
bz> would probably be a matter of third order -- address family.
bz>
bz> Example:
bz>
bz> prefer v6
bz> intorder "tun* gre* gif* wlan* em*"  or similar (maybe classes lik
bz>        "wired" or similar.  not sure how easily we could do that).
bz> progorder "dhcp* rt*"

 Our openresolv currently supports $interface_order with shell pattern
 matching only.  What I thought was

  interface_order="lo lo[0-9]* *:ppp *:slaac *:dhcpv4 [a-z]*[0-9]*:*"

 or something like this.  Actually the interface name in
 resolvconf(8)'s command line argument does not have to be the same as
 real interface names because it is used just for distinguishing the
 information source.  My primary purpose is to prevent multiple RDNSS
 information on a single interface from overwriting /etc/resolv.conf
 anyway.  It can be realized by just adding some additional label.

 Priority control based on ifname and/or protocol (or progname) needs
 no modification to the resolvconf(8) itself if we use this "interface
 name + label", and it looks flexible enough to me.  What we need is a
 consistent expression for that and reasonable default value of
 $interface_order.

 Anyway, the main point here is whether adding an additional label to
 interface id is reasonable or not.  AFAICC, there is no side effect
 by adding the ":origin" part.

bz> Have you discussed that with $upstream vendor as well or do we consider
bz> further changes to be simple enough to merge them in?

 No, I haven't discuss with the upstream yet because supporting
 ":origin[:unique]" part need no change on the resolvconf(8) side (I
 may be missing something here, though).  An experimental patch for
 rtsold is [1] (note that this includes some noises) and one for
 dhclient is [2].  Basically these patches are just for adding
 ":origin" part.

 [1] http://people.allbsd.org/~hrs/FreeBSD/rtsold_aggr_20110616-3.diff
 [2] http://people.allbsd.org/~hrs/FreeBSD/dhclient_resolvconf_20110616-1.diff

 Note that it is possible to have multiple RDNSS sources on a single
 interface in the rtsold case (i.e. multiple routers sending RAs on a
 link).  So "em0:slaac:[RA-source-address]" is used as the interface
 id for that.

-- Hiroki
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