ddm tunnel routing

[rcgoodfellow]

Introduced tunnel routing as described in RFD 404. It's strongly encouraged to read that short RFD before reviewing this PR.

Depends on

• Tunneled routing support for boundary services. opte#381

The primary thing this PR does is add a new tunnel route type and associated advertisement mechanics. Support for adding tunnel routes to OPTE from ddmd is also added.

• Fixes Implement ddm tunnel routing #99

[Nieuwejaar]

Tiny nit: most (all?) of the files have 2022 Copyrights that should be updated.

I pointed out a few specific examples, but in general there are a lot of pub struct types that could use top-level and per-field comments.

It seems like there is a fair bit of boilerplate code converting between structs that are identical, other than their names (e.g., TunnelVector and TunnelOrigin). It's not clear to me why we're not just sharing a common structure.

[rcgoodfellow]

most (all?) of the files have 2022 Copyrights that should be updated.

This has been fixed.

[rcgoodfellow]

It seems like there is a fair bit of boilerplate code converting between structs that are identical, other than their names (e.g., TunnelVector and TunnelOrigin). It's not clear to me why we're not just sharing a common structure.

TunnelVector has been squashed into TunnelOrigin

[rcgoodfellow]

@Nieuwejaar this is ready for another look. The primary things that have changed since you last looked are:

• A static routing API has been added to mgd. In updates for tunnel routing omicron#3859 we shift so using this API instead of sending static routes directly to dpd. This gives mgd visibility of the entire RIB.
• Because mgd now has visibility of the entire RIB, it can manage tunnel advertisements autonomously. Previously, the mg-lower subsystem only monitored changes in the RIB from BGP and made the corresponding routing table updates to dpd. Now, changes to the RIB come from BGP and static routing, and mg-lower will also make tunnel endpoint updates via the local ddm daemon, based on changes in the RIB.

[Nieuwejaar]

I feel like I've only been able to do a tree-level review of this, and it looks good. There's enough here, and it's been long enough since my first look, that I want to revisit the RFD and make another pass to make sure I also have a forest-level view.