The VLAN filter feature is currently implemented completely using the C preprocessor, e.g.:

#define VLAN_FILTER(ifindex, vlan_id) switch (ifindex) { \
case 116: \
switch (vlan_id) { \
case 4000: \
case 4001: \
return true; \
} \
break; \
} \
break; \
} \
return false;

For a related feature, we're looking at adding proper VLAN support for Pods, where this would require a rework anyway. @borkmann Would you be able to give some input or status update?

In the interim, in order to unblock clang-free and to avoid having to turn this into a full subsystem w/ a pinned map, Cell and reconciler, I propose making this a simple [5]uint16 and passing a list of VLANs as an array. The current limit seems to be 5: