gluon-l3roamd: site: make node_client_prefix6 optional+deprecated

[T-X]

The site.node_client_prefix6() is only used internally by the l3roamd protocol. Therefore it is unnecessary to expose it to an administrator.

Instead, if node_client_prefix6 is unspecified in the site, generate an IPv6 Unique Local Address prefix from the site domain_seed.

This updates the site documentation as well and marks this setting as both optional and deprecated.

Note: If you had the node_client_prefix6 specified before and want to use the new autogeneration from the domain_seed instead then this will break compatibility and will need a gluon-scheduled-domain switch.

Signed-off-by: Linus Lüssing <[email protected]>

[T-X]

Commit is rebased on top of #2553.

Tested that the node_client_prefix6() is both correct in the l3roamd command line and in the babel config file. Still ToDo: Test roaming of a client device with the autogenerated prefix.

@mkg20001 @christf

[mkg20001]

@T-X the firewall pr is now merged, could you rebase this then? Other than that LGTM

Edit: The duplicate check_site rules would need to be thrown out, since it was decided to do less duplication.

[T-X]

Changelog v2:

• rebased to current master (renamed gluon-layer3-common to gluon-mesh-layer3-common)
• added node_client_prefix6 to gluon-mesh-layer3-common's check_site.lua, with required=false
• removed additions of prefix6 and node_prefix6 in check_site.lua again

[mkg20001]

I think this is good for merge.