[LEDE-DEV] [PATCH] base-files: config_generate: keep ipv6 interface in sync

[Daniel Golle]

On Wed, Dec 06, 2017 at 05:58:18PM +0100, Matthias Schiffer wrote:
> On 12/06/2017 12:40 AM, Roman Yeryomin wrote:
> > On 2017-12-05 21:52, Hans Dedecker wrote:
> >> On Tue, Dec 5, 2017 at 5:22 PM, Roman Yeryomin <roman at advem.lv> wrote:
> >>> It's better not to configure ifname separately since they
> >>> are tied together.
> >>>
> >>> Signed-off-by: Roman Yeryomin <roman at advem.lv>
> >>> ---
> >>>  package/base-files/files/bin/config_generate | 2 +-
> >>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/package/base-files/files/bin/config_generate
> >>> b/package/base-files/files/bin/config_generate
> >>> index a8311fc595..d7a6829d77 100755
> >>> --- a/package/base-files/files/bin/config_generate
> >>> +++ b/package/base-files/files/bin/config_generate
> >>> @@ -113,7 +113,7 @@ generate_network() {
> >>>                                 set network.$1.proto='dhcp'
> >>>                                 delete network.${1}6
> >>>                                 set network.${1}6='interface'
> >>> -                               set network.${1}6.ifname='$ifname'
> >>> +                               set network.${1}6.ifname='@${1}'
> >>>                                 set network.${1}6.proto='dhcpv6'
> >>>                         EOF
> >>>                 ;;
> >>> -- 
> >>> 2.14.1
> >> NACK
> >>
> >> This makes the IPv6 interface dependant on the operational status of
> >> the IPv4 interface; meaning the IPv6 interface will not be started if
> >> the IPv4 interface does not get an IP address.
> >> Especially this would break wan connectivity if the  wan link only
> >> supports IPv6
> >>
> > 
> > Hmm... right, will just ${1} be better?
> > 
> > Regards,
> > Roman
> 
> No, there is no real interface called 'wan', so it will simply not work at
> all. Logical netifd interface names can only be used in alias
> configurations, but aliases always add a depenency on the 'up' state of the
> aliased interface (so aliases are mostly useful for interfaces that
> actually depend on each other, like a interface depending on a lower interface.
> 
> If you want two configurations not to depend on each other, as we usually
> want for IPv4/IPv6 setup, the current version '$ifname' is exactly right.
> It is also the clearest solution semantically: IPv4 and IPv6 uplink are two
> independent configurations that just share the same physical link in the
> most common setups.

In case the interface-name changes dynamically during runtime (such as
for L2TPv3, ...) we could introduce a common parent with proto 'none'
and then have two child interfaces wan4 and wan6 which refer to the
common parent using the '@' notation.


Cheers


Daniel