modules: main: Add CDDL CBOR encoding of device shadow

Add missing CDDL CBOR decoding of incoming data.
Used to decode update interval set in cloud.

Signed-off-by: Simen S. Røstad <simen.rostad@nordicsemi.no>

Author: simensrostad

app/src/cbor/CMakeLists.txt

@@ -6,3 +6,31 @@
 
 target_sources(app PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/cbor_helper.c)
 target_include_directories(app PRIVATE .)
+
+# generate encoder code using zcbor
+set(zcbor_command
+        zcbor code # Invoke code generation
+	--cddl ${CMAKE_CURRENT_SOURCE_DIR}/device_shadow.cddl
+	--decode # Generate decoding functions
+	--short-names # Attempt to make generated symbol names shorter (at the risk of collision)
+	-t device-shadow # Create a public API for decoding the "device_shadow" type from the cddl file
+	--output-cmake device_shadow.cmake # The generated cmake file will be placed here
+)
+execute_process(COMMAND ${zcbor_command}
+		WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+		COMMAND_ERROR_IS_FATAL ANY)
+
+# Include the cmake file generated by zcbor. It adds the
+# generated code and the necessary zcbor C code files.
+include(${CMAKE_CURRENT_BINARY_DIR}/device_shadow.cmake)
+
+# Ensure that the cmake reconfiguration is triggerred everytime the cddl file changes.
+# This ensures that the codec generation is triggered.
+set_property(
+	DIRECTORY
+	PROPERTY
+	CMAKE_CONFIGURE_DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/device_shadow.cddl
+)
+
+zephyr_link_libraries(device_shadow)
+target_link_libraries(device_shadow PRIVATE zephyr_interface)

app/src/cbor/cbor_helper.c

@@ -5,13 +5,25 @@
  */
 
 #include <zephyr/logging/log.h>
+#include "device_shadow_decode.h"
 
 LOG_MODULE_DECLARE(main, CONFIG_APP_LOG_LEVEL);
 
 int get_update_interval_from_cbor_response(const uint8_t *cbor,
 					   size_t len,
 					   uint64_t *interval_sec)
 {
-	*interval_sec = 1800;
+	struct device_shadow device_shadow = { 0 };
+	size_t not_used;
+
+	int err = cbor_decode_device_shadow(cbor, len, &device_shadow, &not_used);
+
+	if (err) {
+		LOG_ERR("Ignoring incoming configuration change due to decoding error: %d", err);
+		LOG_HEXDUMP_ERR(buf_cbor, buf_cbor_len, "CBOR data");
+		return -EFAULT;
+	}
+
+	*interval_sec = device_shadow.config.update_interval;
 	return 0;
 }

app/src/cbor/device_shadow.cddl

@@ -1,53 +1,4 @@
-; Define the basic structure of the JSON object
-
-; The 'any' type is used in this schema to allow forward compatibility.
-; They are inserted into maps that may contain additional fields in the future.
-; This prevents cbor decoding from failing in the field when the cloud side has new fields.
-app-object = {
-    ? "nrfcloud_mqtt_topic_prefix": tstr,
-    ? "pairing": pairing-type,
-    ? "lwm2m": lwm2m-map,
+config-object = {
+    ? "update_interval": int .size 4,
     * tstr => any
 }
-
-; Define the pairing object with nested topics
-pairing-type = {
-    "state": tstr,
-    "topics": {
-        "d2c": tstr,
-        "c2d": tstr,
-        * tstr => any
-    },
-    * any => any
-}
-
-lwm2m-map = {
-  ? "14240:1.0": led,
-  ? "14301:1.0": config,
-  * tstr => any
-}
-
-led = {
-  "0": led_inner_object,
-  * tstr => any
-}
-
-led_inner_object = {
-  ? "0": int .size 4,
-  ? "1": int .size 4,
-  ? "2": int .size 4,
-  "99": int .size 8,
-  * tstr => any
-}
-
-config = {
-  "0": config_inner_object,
-  * tstr => any
-}
-
-config_inner_object = {
-  ? "0": int .size 8,
-  ? "1": bool,
-  "99": int .size 8,
-  * tstr => any
-}

tests/module/main/src/main.c

@@ -141,7 +141,6 @@ static void send_location_search_done(void)
 	TEST_ASSERT_EQUAL(0, err);
 }
 
-/*
 static void send_config(uint64_t interval)
 {
 	const struct cloud_msg msg = {
@@ -154,7 +153,6 @@ static void send_config(uint64_t interval)
 
 	TEST_ASSERT_EQUAL(0, err);
 }
-*/
 
 static void send_cloud_disconnected(void)
 {
@@ -215,7 +213,6 @@ void test_button_press_on_disconnected(void)
 	check_no_events(7200);
 }
 
-/*
 void test_trigger_interval_change_in_connected(void)
 {
 	send_cloud_connected_ready_to_send();
@@ -231,9 +228,7 @@ void test_trigger_interval_change_in_connected(void)
 	send_cloud_disconnected();
 	check_no_events(WEEK_IN_SECONDS);
 }
-*/
 
-/*
 void test_trigger_disconnect_and_connect_when_triggering(void)
 {
 	send_cloud_connected_ready_to_send();
@@ -256,7 +251,6 @@ void test_trigger_disconnect_and_connect_when_triggering(void)
 	send_cloud_disconnected();
 	check_no_events(WEEK_IN_SECONDS);
 }
-*/
 
 /* This is required to be added to each test. That is because unity's
  * main may return nonzero, while zephyr's main currently must