Hi Rafał, On Wed, 2020-01-29 at 13:17 +0100, Rafal Gajda wrote: > Hi Brian, > > I have a question about the way RPL is stored. > > On Tue, Jan 28, 2020 at 06:32:58PM -0800, Brian Gix wrote: > > Mesh specification requires that Replay Protection be preserved > > across node restarts. This adds that storage in > > <node_uuid>/rpl/<iv_index>/<src> > > Wouldn't it be more convinient to keep both iv_index and sequence in a file like this: > <node_uuid>/rpl/<src> > ? > > You could store them in bytes instead of hex string > and it would eliminate the need for cleaning entries from old IV_index. We considered this and decided against it for ease of processing, as this method requires fewer file operations. Cleaning old entries is something that will happen regardless of how the RPL tree looks in the file system, as we delete entries that are older than (net->iv_index - 1) since we don't receive messages on that iv_index, there is no possiblility of a Replay attack. And deleting a file system tree is pretty simple. A SRC address does not get to keep it's spot in the RPL indefinitely... only over the current or prior iv_index. Our other considerations included maintaining the integrity of the RPL across power-loss or abort reboots. However, we do recognize that some platforms may different NVM storage available that can be optimized in different ways, so we tried to keep the NVM RPL apis as simple as possible to allow others to optimize the storage as they see fit. For instance, if someone was to port this to an embedded system without a standard linux file system.
