fact does not cleanup the LPM prefix map in kernel side

[Molter73]

Found this due to a crash in this line:

fact/fact/src/bpf/mod.rs

Line 174 in 3811f0d

path_prefix.insert(&prefix.into(), 0, 0)?;

When a new set of paths is received, we probably want to find the ones from the previous set that are not in the new one and remove those prefixes from the map to reduce the chance of crashes.

We also probably want to bump that prefix limit and make it configurable.

[Molter73]

After some more investigating, it seems the problem arises from the case where the new configuration has no prefixes, which doesn't cleanup the map properly:

fact/fact/src/bpf/mod.rs

Lines 141 to 146 in 6ba96be

	if self.paths_config.borrow().is_empty() {
	self.detach_progs();
	self.paths.clear();
	self.paths_globset = GlobSet::empty();
	return Ok(());
	}

Should have a fix for this soon enough.