bluetooth: mesh: update le pair responder model with BT_APP_PASSKEY

BT_FIXED_PASSKEY is depracated so wee need to aling the le pair
responder model with the new Kconfig BT_APP_PASSKEY usage.

Adding bt_mesh_le_pair_resp_passkey_get to be able to retreive
the passkey set randomly or by app.

Signed-off-by: alperen sener <[email protected]>

Author: m-alperen-sener

doc/nrf/libraries/bluetooth/mesh/vnd/images/bt_mesh_le_pair_resp.svg

@@ -7,22 +7,15 @@ LE Pairing Responder
    :local:
    :depth: 2
 
-The LE Pairing Responder model is a vendor model.
+The LE Pairing Responder model is a vendor model and it requires :kconfig:option:`CONFIG_BT_APP_PASSKEY` option to be enabled.
 This model can be used to hand over a passkey that will authenticate a Bluetooth LE connection over a mesh network when it is not possible to use other pairing methods.
 
-Before the pairing is initiated, an initiator should send an LE Pairing message with Passkey Reset sub-opcode to set a new passkey for the next pairing request.
+Before the pairing is initiated, an initiator should send an LE Pairing message with Passkey Reset sub-opcode. If the passkey has been set by the :c:func:`bt_mesh_le_pair_resp_passkey_set` function, the predefined passkey will be returned in the Passkey Status message. Otherwise, a new passkey will be generated by LE Pairing Responder model and returned in the Passkey Status message.
 The passkey returned in the LE Pairing message with the Passkey Status sub-opcode should be used for the next pairing.
 
-The passkey is generated using the :c:func:`bt_rand` function and set to the host using the :c:func:`bt_passkey_set` function.
-The latter requires the :kconfig:option:`CONFIG_BT_FIXED_PASSKEY` option to be enabled.
-
-.. note::
-   The warning generated by the :kconfig:option:`CONFIG_BT_FIXED_PASSKEY` option should be disregarded as long as the application always invalidates the previously used passkey by calling the :c:func:`bt_mesh_le_pair_resp_passkey_invalidate` function regardless of the pairing result (see below).
-
-This model requires an application to only enable the display capability for the LE pairing by setting the :c:member:`bt_conn_auth_cb.pairing_display` callback.
-After every pairing request, the application must invalidate the previously used passkey by calling the :c:func:`bt_mesh_le_pair_resp_passkey_invalidate` function.
-This function can be called from callbacks :c:member:`bt_conn_auth_info_cb.pairing_complete` and :c:member:`bt_conn_auth_info_cb.pairing_failed`.
-See the :file:`samples/bluetooth/mesh/common/smp_bt_auth.c` file for the reference.
+This model requires an application to only enable the display capability for the LE pairing by setting the :c:member:`bt_conn_auth_cb.pairing_display` callback. The application must also set the :c:member:`bt_conn_auth_cb.app_passkey` callback to use the passkey generated by LE Pairing Responder model.
+After every pairing request, the application must invalidate the previously used passkey by calling the :c:func:`bt_mesh_le_pair_resp_passkey_invalidate` function or calling :c:func:`bt_mesh_le_pair_resp_passkey_set` with :ref:`BT_PASSKEY_RAND` value.
+Those functions can be called from callbacks :c:member:`bt_conn_auth_info_cb.pairing_complete` and :c:member:`bt_conn_auth_info_cb.pairing_failed`.  See the :file:`samples/bluetooth/mesh/common/smp_bt_auth.c` file for the reference.
 
 .. figure:: images/bt_mesh_le_pair_resp.svg
    :alt: Diagram of interaction between an Initiator and the LE Pairing Responder model

doc/nrf/libraries/bluetooth/mesh/vnd/le_pair_resp.rst

@@ -163,6 +163,10 @@ Bluetooth Mesh
   * Deprecated the :kconfig:option:`CONFIG_BT_MESH_NLC_PERF_CONF` and :kconfig:option:`CONFIG_BT_MESH_NLC_PERF_DEFAULT` Kconfig options.
     Existing configurations continue to work but you should migrate to individual profile options.
 
+* Update the LE Pairing Responder model:
+
+  * Deprecated the :kconfig:option:`CONFIG_BT_FIXED_PASSKEY` option in favor of the new and supported :kconfig:option:`CONFIG_BT_APP_PASSKEY` option.
+
 DECT NR+
 --------
 
@@ -386,6 +390,8 @@ Bluetooth Mesh samples
   * Updated the :makevar:`FILE_SUFFIX` make variable to use more descriptive suffixes for external flash configurations.
     The new suffixes are ``_dfu_ext_flash`` for external flash DFU storage and ``_ext_flash_settings`` for external flash settings storage.
 
+  * Updated the sample to use the :kconfig:option:`CONFIG_BT_APP_PASSKEY` option instead of the deprecated :kconfig:option:`CONFIG_BT_FIXED_PASSKEY` option.
+
 * :ref:`ble_mesh_dfu_target` sample:
 
   * Added:

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -43,11 +43,23 @@ void bt_mesh_le_pair_resp_passkey_invalidate(void);
  * By default, passkeys will be randomly generated on every new request. This function allows to use
  * pre-defined passkey instead.
  *
- * @params passkey Passkey to use for the pairing, or @ref BT_PASSKEY_INVALID to use randomly
+ * @params passkey Passkey to use for the pairing, or @ref BT_PASSKEY_RAND to use randomly
  *		   generated passkey again.
  */
 void bt_mesh_le_pair_resp_passkey_set(uint32_t passkey);
 
+/** @brief Get passkey to be used in the very next pairing.
+ *
+ * This function will return the passkey set by the @ref bt_mesh_le_pair_resp_passkey_set function or it will return
+ * a randomly generated passkey by the Reset message.
+ *
+ * If the passkey has never been set or the Reset message has never been received, @ref BT_PASSKEY_RAND will be returned.
+ *
+ * @return Passkey to be used in the very next pairing;
+ *		   @ref BT_PASSKEY_RAND if passkey is not set.
+ */
+uint32_t bt_mesh_le_pair_resp_passkey_get(void);
+
 /** @cond INTERNAL_HIDDEN */
 
 extern const struct bt_mesh_model_op _bt_mesh_le_pair_resp_op[];

include/bluetooth/mesh/vnd/le_pair_resp.h

@@ -85,10 +85,10 @@ config BT_MESH_DM_SRV_REFLECTOR_RANGING_WINDOW_US
 endif # BT_MESH_DM_SRV
 
 config BT_MESH_LE_PAIR_RESP
-	bool "LE Pairing Responder model"
+	bool "LE Pairing Responder model [EXPERIMENTAL]"
 	select BT_MESH_VENDOR_MODELS
 	select EXPERIMENTAL
-	depends on BT_FIXED_PASSKEY
+	depends on BT_APP_PASSKEY
 	depends on BT_SMP_SC_ONLY
 	help
 	  Enable the LE Pairing Responder model. The LE Pairing Responder model is used to generate

subsys/bluetooth/mesh/vnd/Kconfig

@@ -24,31 +24,27 @@ LOG_MODULE_REGISTER(bt_mesh_le_pair_resp);
 #define STATUS_PASSKEY_SET 0x00
 #define STATUS_PASSKEY_NOT_SET 0x01
 
-static uint32_t predefined_passkey = BT_PASSKEY_INVALID;
+static uint32_t predefined_passkey = BT_PASSKEY_RAND;
 
 static int handle_reset(const struct bt_mesh_model *model, struct bt_mesh_msg_ctx *ctx,
 			struct net_buf_simple *buf)
 {
 	uint32_t passkey;
 	uint8_t status = STATUS_PASSKEY_SET;
-	int err;
 
 	if (buf->len != 0) {
 		return -EINVAL;
 	}
 
 	BT_MESH_MODEL_BUF_DEFINE(rsp, BT_MESH_LE_PAIR_OP, 5);
 
-	if (predefined_passkey != BT_PASSKEY_INVALID) {
+	if (predefined_passkey != BT_PASSKEY_RAND) {
 		passkey = predefined_passkey;
 	} else {
 		passkey = sys_rand32_get() % 1000000;
-	}
-
-	err = bt_passkey_set(passkey);
-	if (err) {
-		LOG_ERR("Unable to set passkey (err: %d)", err);
-		status = STATUS_PASSKEY_NOT_SET;
+		/* Overwrite the predefined passkey with the randomly generated passkey.
+		So the le pair responder can use the randomly generated passkey for the next pairing request.*/
+		predefined_passkey = passkey;
 	}
 
 	bt_mesh_model_msg_init(&rsp, BT_MESH_LE_PAIR_OP);
@@ -112,10 +108,15 @@ const struct bt_mesh_model_cb _bt_mesh_le_pair_resp_cb = {
 
 void bt_mesh_le_pair_resp_passkey_invalidate(void)
 {
-	(void)bt_passkey_set(BT_PASSKEY_INVALID);
+	predefined_passkey = BT_PASSKEY_RAND;
 }
 
 void bt_mesh_le_pair_resp_passkey_set(uint32_t passkey)
 {
 	predefined_passkey = passkey;
 }
+
+uint32_t bt_mesh_le_pair_resp_passkey_get(void)
+{
+	return predefined_passkey;
+}