Move util code to lock_utils

Signed-off-by: Hunsup Jung <hunsup.jung@samsung.com>

Author: HunsupJung

drivers/SmartThings/matter-lock/src/lock_utils.lua

@@ -1,6 +1,9 @@
 -- Copyright 2022 SmartThings, Inc.
 -- Licensed under the Apache License, Version 2.0
 
+local security = require "st.security"
+local PUB_KEY_PREFIX = "04"
+
 local lock_utils = {
   -- Lock device field names
   LOCK_CODES = "lockCodes",
@@ -41,7 +44,8 @@ local lock_utils = {
   DEVICE_KEY_ID = "deviceKeyId",
   COMMAND_REQUEST_ID = "commandRequestId",
   MODULAR_PROFILE_UPDATED = "__MODULAR_PROFILE_UPDATED",
-  ALIRO_READER_CONFIG_UPDATED = "aliroReaderConfigUpdated"
+  ALIRO_READER_CONFIG_UPDATED = "aliroReaderConfigUpdated",
+  LATEST_DOOR_LOCK_FEATURE_MAP = "__latest_door_lock_feature_map"
 }
 local capabilities = require "st.capabilities"
 local json = require "st.json"
@@ -104,6 +108,13 @@ end
 -- keys are the code slots that ST uses
 -- user_index and credential_index are used in the matter commands
 --
+function lock_utils.get_field_for_endpoint(device, field, endpoint)
+  return device:get_field(string.format("%s_%d", field, endpoint))
+end
+
+function lock_utils.set_field_for_endpoint(device, field, endpoint, value, additional_params)
+  device:set_field(string.format("%s_%d", field, endpoint), value, additional_params)
+end
 
 function lock_utils.optional_capabilities_list_changed(new_component_capability_list, previous_component_capability_list)
   local previous_capability_map = {}
@@ -146,4 +157,121 @@ function lock_utils.optional_capabilities_list_changed(new_component_capability_
   return false
 end
 
+-- This function check busy_state and if busy_state is false, set it to true(current time)
+function lock_utils.is_busy_state_set(device)
+  local c_time = os.time()
+  local busy_state = device:get_field(lock_utils.BUSY_STATE) or false
+  if busy_state == false or c_time - busy_state > 10 then
+    device:set_field(lock_utils.BUSY_STATE, c_time, {persist = true})
+    return false
+  else
+    return true
+  end
+end
+
+function lock_utils.hex_string_to_octet_string(hex_string)
+  if hex_string == nil then
+    return nil
+  end
+  local octet_string = ""
+  for i = 1, #hex_string, 2 do
+      local hex = hex_string:sub(i, i + 1)
+      octet_string = octet_string .. string.char(tonumber(hex, 16))
+  end
+  return octet_string
+end
+
+function lock_utils.create_group_id_resolving_key()
+  math.randomseed(os.time())
+  local result = string.format("%02x", math.random(0, 255))
+  for i = 1, 15 do
+    result = result .. string.format("%02x", math.random(0, 255))
+  end
+  return result
+end
+
+function lock_utils.generate_keypair(device)
+  local request_opts = {
+    key_algorithm = {
+      type = "ec",
+      curve = "prime256v1"
+    },
+    signature_algorithm = "sha256",
+    return_formats = {
+      pem = true,
+      der = true
+    },
+    subject = {
+      common_name = "reader config"
+    },
+    validity_days = 36500,
+    x509_extensions = {
+      key_usage = {
+        critical = true,
+        digital_signature = true
+      },
+      certificate_policies = {
+        critical = true,
+        policy_2030_5_self_signed_client = true
+      }
+    }
+  }
+  local status = security.generate_self_signed_cert(request_opts)
+  if not status or not status.key_der then
+    device.log.error("generate_self_signed_cert returned no data")
+    return nil, nil
+  end
+
+  local der = status.key_der
+  local privKey, pubKey = nil, nil
+  -- Helper: Parse ASN.1 length (handles 1-byte and multi-byte lengths)
+  local function get_length(data, start_pos)
+    local b = string.byte(data, start_pos)
+    if not b then return nil, start_pos end
+
+    if b < 0x80 then
+      return b, start_pos + 1
+    else
+      local num_bytes = b - 0x80
+      local len = 0
+      for i = 1, num_bytes do
+        len = (len * 256) + string.byte(data, start_pos + i)
+      end
+      return len, start_pos + 1 + num_bytes
+    end
+  end
+  -- Start parsing after the initial SEQUENCE tag (0x30)
+  -- Most keys start: [0x30][Length]. We find the first length to find the start of content.
+  local _, pos = get_length(der, 2)
+
+  while pos < #der do
+    local tag = string.byte(der, pos)
+    local len, content_start = get_length(der, pos + 1)
+    if not len then break end
+    if tag == 0x04 then
+      -- PRIVATE KEY: Octet String
+      privKey = utils.bytes_to_hex_string(string.sub(der, content_start, content_start + len - 1))
+    elseif tag == 0xA1 then
+      -- PUBLIC KEY Wrapper: Explicit Tag [1]
+      -- Inside 0xA1 is a BIT STRING (0x03)
+      local inner_tag = string.byte(der, content_start)
+      if inner_tag == 0x03 then
+        local bit_len, bit_start = get_length(der, content_start + 1)
+        -- BIT STRINGS have a "leading null byte" (unused bits indicator)
+        -- We skip that byte (bit_start) and the 0x04 EC prefix to get the raw X/Y coordinates
+        local actual_key_start = bit_start + 2
+        local actual_key_len = bit_len - 2
+        pubKey = PUB_KEY_PREFIX .. utils.bytes_to_hex_string(string.sub(der, actual_key_start, actual_key_start + actual_key_len - 1))
+      end
+    end
+    -- Move pointer to the next tag
+    pos = content_start + len
+  end
+
+  if not privKey or not pubKey then
+    device.log.error("Failed to extract keys from DER")
+  end
+  return privKey, pubKey
+end
+
 return lock_utils