Hi Michał,
On Thu, 2019-09-05 at 15:12 +0200, Michał Lowas-Rzechonek wrote:
> This fixes erroneously cleared sequence number when node performs IV
> Recovery procedure on startup in a following scenario:
> - node has IV Index set to <N>
> - node starts in IV_UPD_INIT state
> - node receives a Secure Network Beacon with IV Index <N>+1 and IV
> Update flag set
>
> Upon reception, the node shall:
> - increase its IV Index to <N>+1
> - enter IV_UPD_UPDATING state
>
> This means that the node keeps transmitting messages using IV Index
> equal to <N>, therefore it shall not reset its Sequence Number before IV
> Update procedure completes.
>
> If, on the other hand, received Secure Network Beacon contains IV Index
> <N>+2 (or more), the node shall:
> - increase its IV Index to <N>+2 (or more)
> - enter IV_UPD_UPDATING state
> - reset the Sequence Number to 0
> ---
> mesh/net.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mesh/net.c b/mesh/net.c
> index 2785039db..b4b390541 100644
> --- a/mesh/net.c
> +++ b/mesh/net.c
> @@ -2735,7 +2735,7 @@ static void update_iv_kr_state(struct mesh_subnet *subnet, uint32_t iv_index,
> }
>
> if (net->iv_upd_state == IV_UPD_INIT) {
> - if (iv_index > net->iv_index)
> + if (iv_index > net->iv_index + 1)
> mesh_net_set_seq_num(net, 0);
I think you have found something, but I think we are missing something here...
If iv_index > net->iv_index, and iv_update == false, then we still want to reset to Seq Zero, I think...Even if
the increase is just 1.
This particular path is just covering the situation where this is the *first* SNB we are receiving after node
start-up (iv_upd_state == INIT) and it is very possible that the node has been away for long enough that a
single IV Update has started and finished.
So perhaps:
if (iv_index > net->iv_index && !iv_update)
mesh_net_set_seq_num(net, 0);
else if (iv_index > net->iv_index + 2)
mesh_net_set_seq_num(net, 0);
Or more esoterically (and maybe harder to follow):
if (iv_index > net->iv_index + iv_update)
mesh_net_set_seq_num(net, 0);
Or something like that.
> net->iv_index = iv_index;
>
