add rich representation for VLAN QOS mapping

[jreppnow]

Hi!

Thanks for the cool crates. This PR adds a rich representation for VLAN QOS mappings.
This is mainly used to allow user space applications to use the SOL_PRIORITY flag to set VLAN priority for their sockets.

I used the implementation here as a reference: https://github.com/shemminger/iproute2/blob/main/ip/iplink_vlan.c

Notes:

• I used the rich_nlas feature flag for this, but since it existed before, this might still be a breaking change for some users. Could alternatively introduce another feature flag specifically for this change.
• Once this is accepted, I would also like to add corresponding functionality in the rtnetlink crate.

[jreppnow]

The captured data in the test case is from:

sudo strace -s 1000 -f -e trace=network ip link add link enp5s0 name eth0.75 type vlan id 75 egress 3:4 ingress 0:1 1:2

I had to adjust the length field for IFLA_INFO_KIND and add the padding manually, as iproute2 does not use null-terminated strings (aka c strings) for this specific field.

[cathay4t]

@jreppnow Thanks for the patch! Please rebase to latest commit.

I personally dislike the idea of rich_nlas feature and plan to remove it in next release 0.17.0. Hence please remove the use of rich_nlas from your code. Thanks!

I guess this VLAN QoS support also require effort on rtnetlink crate, can you provide a PR to rtnetlink with example code approving the code here is actual working?

Thank you!

[jreppnow]

Hi @cathay4t,

1. I have made the requested changes here (rebase and removal of rich_nlas feature).
2. Made a (preliminary) PR (add support for vlan QOS rtnetlink#24) to rtnetlink making use of the changes here. See the notes there for more details.

[codecov]

Codecov Report

Merging #33 (224d5b9) into main (b6de604) will increase coverage by 1.15%.
The diff coverage is 84.41%.

@@            Coverage Diff             @@
##             main      #33      +/-   ##
==========================================
+ Coverage   45.08%   46.23%   +1.15%     
==========================================
  Files          75       75              
  Lines        6208     6276      +68     
==========================================
+ Hits         2799     2902     +103     
+ Misses       3409     3374      -35     

Impacted Files	Coverage Δ
src/rtnl/link/nlas/link_infos.rs	50.92% <84.41%> (+5.78%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[cathay4t]

Looks great to me.

Please change the commit message title since we are not using rick_nlas anymore in this patch.

After that, we are good to go.

The title is good enough

[cathay4t]

My bad the commit title is good enough. Merging.