IGMP version higher than net.inet.igmp.default_version

[etihwo]

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• [x] I have read the contributing guide lines at https://github.com/opnsense/src/blob/master/CONTRIBUTING.md
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Describe the bug

The tunable net.inet.igmp.default_version has not effect on the IGMP version used on interfaces. The problem was also present in 24.7.

Tip: to validate your setup was working with the previous version, use opnsense-revert (https://docs.opnsense.org/manual/opnsense_tools.html#opnsense-revert)

To Reproduce

Steps to reproduce the behavior:

1. Go to 'System: Settings: Tunables' and set 2 for net.inet.igmp.default_version
2. Apply settings and reboot to be sure that change is taken into account
3. Open a shell and run sysctl net.inet.igmp to see that default_version is 2
4. Run ifmcstat -f inet to notice that igmpv3 is indicated for each interface

Expected behavior

When runing the command ifmcstat -f inet, the igmp version should be less or equal than the net.inet.igmp.default_version

Describe alternatives you considered

I have applied the commit https://github.com/freebsd/freebsd-src/commit/b94ec00ba73ef4769f62555bfcb840919143e198 as this topic has been discussed in the main branch of FreeBSD. However, it is not sufficient and ifmcstat -f inet still indicate version 3.

In addition to the commit above, I have changed VNET_DEFINE_STATIC(int, igmp_default_version) = IGMP_VERSION_2; in igmp.c. This modification allows:

• to have IGMPv2 after a reboot
• to switch to IGMPv3 at runtime if net.inet.igmp.default_version is set to 3

However, this modification does not allow:

• to switch from IGMPv3 to IGMPv2 at runtime

Environment

OPNsense 25.1 (amd64)

[etihwo]

To answer to myself, I found a solution which is to update the function sysctl_igmp_default_version to update igmp version of each interface when the actual value is above the new value defined in net.inet.igmp.default_version. This way, at runtime, the igmp version can go from IGMPv3 to IGMPv2 as soon as the version is switched and IGMPv2 to IGMPv3 after the timeout for IGMPv2.

The solution is to :

• apply https://github.com/freebsd/freebsd-src/commit/b94ec00ba73ef4769f62555bfcb840919143e198
• apply the patch in the attached file

patch.patch

[etihwo]

The issue is corrected in the upstream repo. However, it is not in the 14.x branch.