T5007: Fix multicast implementation for the tunnel interfaces

[sever-sever]

Change Summary

Multicast has not been implemented for the tunnel interfaces. We have only configuration CLI commands that do anything. Fix it.

  ip link set dev <tag> multicast on
  ip link set dev <tag> multicast off

(cherry picked from commit ac821d0)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe): cherry-pick multicast for tunnels

Related Task(s)

• https://vyos.dev/T5007

Component(s) name

tunnel

Proposed changes

How to test

VyOS config:

set interfaces tunnel tun0 encapsulation 'gre'
set interfaces tunnel tun0 multicast 'enable'
set interfaces tunnel tun0 remote '192.0.2.85'
set interfaces tunnel tun0 source-address '203.0.113.1'

Before the fix, we don't see the flag MULTICAST

vyos@r1# ip -j link show dev tun0 |  python3 -c "import sys, json; print(json.load(sys.stdin)[0]['flags'])"
['POINTOPOINT', 'NOARP', 'UP', 'LOWER_UP']
[edit]
vyos@r1# 
[edit]
vyos@r1# sudo ip -d link show dev tun0
9: tun0@NONE: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/gre 203.0.113.1 peer 192.0.2.85 promiscuity 0 minmtu 68 maxmtu 65511 
    gre remote 192.0.2.85 local 203.0.113.1 ttl 64 tos inherit addrgenmode none numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 
[edit]
vyos@r1# 

After the fix, the expected flag MULTICAST

vyos@r1# ip -j link show dev tun0 |  python3 -c "import sys, json; print(json.load(sys.stdin)[0]['flags'])"
['POINTOPOINT', 'MULTICAST', 'NOARP', 'UP', 'LOWER_UP']
[edit]
vyos@r1# 
[edit]
vyos@r1# sudo ip -d link show dev tun0
10: tun0@NONE: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/gre 203.0.113.1 peer 192.0.2.85 promiscuity 0 minmtu 68 maxmtu 65511 
    gre remote 192.0.2.85 local 203.0.113.1 ttl 64 tos inherit addrgenmode none numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 
[edit]
vyos@r1# 

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly