5 files changed, 66 insertions, 16 deletions

diff --git a/fw/app/prj.conf b/fw/app/prj.conf
index 4981bea..6589ec0 100644
--- a/fw/app/prj.conf
+++ b/fw/app/prj.conf
@@ -57,3 +57,5 @@ CONFIG_SETTINGS_NVS=y
 CONFIG_SETTINGS_SHELL=y
 
 CONFIG_GNU_C_EXTENSIONS=y
+
+CONFIG_JSON_LIBRARY=y
diff --git a/fw/app/src/http.c b/fw/app/src/http.c
index 83a3568..1c24490 100644
--- a/fw/app/src/http.c
+++ b/fw/app/src/http.c
@@ -5,6 +5,7 @@
  */
 
 
+#include <errno.h>
 #include <stdint.h>
 
 #include <zephyr/init.h>
@@ -101,14 +102,24 @@ static int settings_handler(
 ) {
 	static char buffer[100];
 
-	int ret = settings_to_json(buffer, sizeof(buffer));
+	int ret = settings_to_json(buffer, sizeof(buffer) - 1);
 	if (ret < 0) {
 		LOG_ERR("Could not serialize payload for settings request");
 		return ret;
 	}
 
+	size_t len = strnlen(buffer, sizeof(buffer));
+	if (len + 2 > sizeof(buffer)) {
+		LOG_ERR("Settings JSON requires %d octets but buffer has only %d",
+		        len + 2, sizeof(buffer));
+		return -ENOMEM;
+	}
+
+	buffer[len] = '\n';
+	buffer[len + 1] = '\0';
+
 	response_ctx->body = (const uint8_t *)buffer;
-	response_ctx->body_len = ret;
+	response_ctx->body_len = len + 1;
 	response_ctx->final_chunk = true;
 	response_ctx->status = HTTP_200_OK;
 
diff --git a/fw/app/src/settings.c b/fw/app/src/settings.c
index 89f2f88..4b2c248 100644
--- a/fw/app/src/settings.c
+++ b/fw/app/src/settings.c
@@ -4,9 +4,9 @@
  * obtain one at https://mozilla.org/MPL/2.0/.
  */
 
+#include <string.h>
 
-#include <stdio.h>
-
+#include <zephyr/data/json.h>
 #include <zephyr/init.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/settings/settings.h>
@@ -36,27 +36,42 @@ int init_settings(void) {
 }
 SYS_INIT(init_settings, APPLICATION, 50);
 
+static const struct json_obj_descr settings_syslog_target_descr[] = {
+	JSON_OBJ_DESCR_PRIM(struct settings_syslog_target, ip, JSON_TOK_STRING),
+};
+
+static const struct json_obj_descr settings_syslog_descr[] = {
+	JSON_OBJ_DESCR_OBJECT(struct settings_syslog, target, settings_syslog_target_descr),
+};
+
+static const struct json_obj_descr settings_descr[] = {
+	JSON_OBJ_DESCR_OBJECT(struct settings, syslog, settings_syslog_descr),
+};
+
 int settings_to_json(void *buffer, size_t len)
 {
-	static const char format[] = "{\"syslog\":{\"target\":{\"ip\":\"%s\"}}}\n";
+	struct settings settings = {0,};
+	settings.syslog.target.ip = (char *)settings.syslog.target.ip_array;
 
-	char ip[100];
-	int ret = settings_runtime_get("syslog/target/ip", ip, sizeof(ip));
+	int ret = settings_runtime_get("syslog/target/ip",
+	                               settings.syslog.target.ip_array,
+	                               sizeof(settings.syslog.target.ip_array));
 	if (ret < 0) {
 		LOG_ERR("Failed to get runtime setting syslog/target/ip (%d)", ret);
 		return ret;
 	}
 
-	ret = snprintf(buffer, len, format, ip);
-
-	if (ret >= len) {
-		LOG_ERR("Buffer too small to serialize settings as JSON");
-		return -ENOMEM;
-	}
-
+	ret = json_obj_encode_buf(
+		settings_descr,
+		ARRAY_SIZE(settings_descr),
+		&settings,
+		buffer,
+		len
+	);
 	if (ret < 0) {
 		LOG_ERR("Failed to serialize settings as JSON");
+		return ret;
 	}
 
-	return ret;
+	return 0;
 }
diff --git a/fw/app/src/settings.h b/fw/app/src/settings.h
index a5cf2ac..290d1ff 100644
--- a/fw/app/src/settings.h
+++ b/fw/app/src/settings.h
@@ -4,8 +4,29 @@
  * obtain one at https://mozilla.org/MPL/2.0/.
  */
 
+#ifndef SRC_SETTINGS_H
+#define SRC_SETTINGS_H
 
 #include <stddef.h>
 
+#include <zephyr/data/json.h>
+
+#define IPV6_STRLEN_MAX 39  // excluding '\0'
+
+
+struct settings_syslog_target {
+	char ip_array[IPV6_STRLEN_MAX];
+	char *ip;  /* Zephyr's JSON lib does not work with arrays directly */
+};
+
+struct settings_syslog {
+	struct settings_syslog_target target;
+};
+
+struct settings {
+	struct settings_syslog syslog;
+};
 
 int settings_to_json(void *buffer, size_t data);
+
+#endif  // !SRC_SETTINGS_H
diff --git a/fw/app/src/syslog.c b/fw/app/src/syslog.c
index 700547b..22aa034 100644
--- a/fw/app/src/syslog.c
+++ b/fw/app/src/syslog.c
@@ -25,11 +25,12 @@
 #include <zephyr/sys/reboot.h>
 #endif  // CONFIG_IOT_CONTACT_NETWORK_HACK
 
+#include "settings.h"
+
 LOG_MODULE_REGISTER(syslog);
 
 #define NETWORK_BUG_DELAY K_MSEC(4000)
 #define L4_EVENT_MASK (NET_EVENT_L4_CONNECTED | NET_EVENT_L4_DISCONNECTED)
-#define IPV6_STRLEN_MAX 39  // excluding '\0'
 #define SYSLOG_TARGET_PORT 514
 
 struct net_mgmt_event_callback l4_cb;