@@ -7,6 +7,10 @@ defmodule NervesKey do
77 alias NervesKey . { Config , OTP , Data , ProvisioningInfo }
88
99 @ build_year DateTime . utc_now ( ) . year
10+ @ settings_slots [ 8 , 7 , 6 , 5 ]
11+ @ settings_max_length Enum . reduce ( @ settings_slots , 0 , fn slot , acc ->
12+ acc + ATECC508A.DataZone . slot_size ( slot )
13+ end )
1014
1115 @ typedoc "Which device/signer certificate pair to use"
1216 @ type certificate_pair ( ) :: :primary | :aux
@@ -230,6 +234,91 @@ defmodule NervesKey do
230234 % ProvisioningInfo { manufacturer_sn: Base . encode32 ( sn , padding: false ) , board_name: "NervesKey" }
231235 end
232236
237+ @ doc """
238+ Return the settings block as a binary
239+ """
240+ @ spec get_raw_settings ( ATECC508A.Transport . t ( ) ) :: { :ok , binary ( ) } | { :error , atom ( ) }
241+ def get_raw_settings ( transport ) do
242+ all_reads = Enum . map ( @ settings_slots , & ATECC508A.DataZone . read ( transport , & 1 ) )
243+
244+ case Enum . find ( all_reads , fn { result , _ } -> result != :ok end ) do
245+ nil ->
246+ raw = Enum . map_join ( all_reads , fn { :ok , contents } -> contents end )
247+ { :ok , raw }
248+
249+ error ->
250+ error
251+ end
252+ end
253+
254+ @ doc """
255+ Return all of the setting stored in the NervesKey as a map
256+ """
257+ @ spec get_settings ( ATECC508A.Transport . t ( ) ) :: { :ok , map ( ) } | { :error , atom ( ) }
258+ def get_settings ( transport ) do
259+ with { :ok , raw_settings } <- get_raw_settings ( transport ) do
260+ try do
261+ settings = :erlang . binary_to_term ( raw_settings , [ :safe ] )
262+ { :ok , settings }
263+ catch
264+ _ , _ -> { :error , :corrupt }
265+ end
266+ end
267+ end
268+
269+ @ doc """
270+ Store settings on the NervesKey
271+
272+ This overwrites all of the settings that are currently on the key and should
273+ be used with care since there's no protection against a race condition with
274+ other NervesKey users.
275+ """
276+ @ spec put_settings ( ATECC508A.Transport . t ( ) , map ( ) ) :: :ok
277+ def put_settings ( transport , settings ) when is_map ( settings ) do
278+ raw_settings = :erlang . term_to_binary ( settings )
279+ put_raw_settings ( transport , raw_settings )
280+ end
281+
282+ @ doc """
283+ Store raw settings on the Nerves Key
284+
285+ This overwrites all of the settings and should be used with care since there's
286+ no protection against race conditions with other users of this API.
287+ """
288+ @ spec put_raw_settings ( ATECC508A.Transport . t ( ) , binary ( ) ) :: :ok
289+ def put_raw_settings ( transport , raw_settings ) when is_binary ( raw_settings ) do
290+ if byte_size ( raw_settings ) > @ settings_max_length do
291+ raise "Settings are too large and won't fit in the NervesKey. The max raw size is #{
292+ @ settings_max_length
293+ } ."
294+ end
295+
296+ padded_settings = pad ( raw_settings , @ settings_max_length )
297+ slots = break_into_slots ( padded_settings , @ settings_slots )
298+
299+ Enum . each ( slots , fn { slot , data } -> ATECC508A.DataZone . write ( transport , slot , data ) end )
300+ end
301+
302+ defp pad ( bin , len ) when byte_size ( bin ) < len do
303+ to_pad = 8 * ( len - byte_size ( bin ) )
304+ << bin :: binary , 0 :: size ( to_pad ) >>
305+ end
306+
307+ defp pad ( bin , _len ) , do: bin
308+
309+ defp break_into_slots ( bin , slots ) do
310+ break_into_slots ( bin , slots , [ ] )
311+ |> Enum . reverse ( )
312+ end
313+
314+ defp break_into_slots ( << >> , [ ] , result ) , do: result
315+
316+ defp break_into_slots ( bin , [ slot | rest ] , result ) do
317+ slot_len = ATECC508A.DataZone . slot_size ( slot )
318+ { contents , next } = :erlang . split_binary ( bin , slot_len )
319+ break_into_slots ( next , rest , [ { slot , contents } | result ] )
320+ end
321+
233322 # Configure an ATECC508A or ATECC608A as a NervesKey.
234323 #
235324 # This is called from `provision/4`. It can be called multiple
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