fw: app: http: Refactor settings handlersettings

2 files changed, 13 insertions, 7 deletions

diff --git a/fw/app/src/http.c b/fw/app/src/http.c
index 88cf579..f9016c1 100644
--- a/fw/app/src/http.c
+++ b/fw/app/src/http.c
@@ -100,26 +100,31 @@ static int settings_handler(
 	struct http_response_ctx *response_ctx,
 	void *user_data
 ) {
-	static char buffer[100];
+	static char buffer[SETTINGS_JSON_MAX_LEN];
 
-	int ret = settings_to_json(buffer, sizeof(buffer) - 1);
+	int ret = settings_to_json(buffer, sizeof(buffer));
 	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));
+	if (len >= sizeof(buffer)) {
+		LOG_ERR("End of settings JSON string not found (strnlen returned %d)",
+		        sizeof(buffer));
 		return -ENOMEM;
 	}
 
-	buffer[len] = '\n';
+	if (sizeof(buffer) < len + 2) {
+		LOG_ERR("Settings JSON buffer too small to hold \\n and \\0");
+		return -ENOMEM;
+	}
+	buffer[len + 0] = '\n';
 	buffer[len + 1] = '\0';
+	len += 1;
 
 	response_ctx->body = (const uint8_t *)buffer;
-	response_ctx->body_len = len + 1;
+	response_ctx->body_len = len;
 	response_ctx->final_chunk = true;
 	response_ctx->status = HTTP_200_OK;
 
diff --git a/fw/app/src/settings.h b/fw/app/src/settings.h
index 290d1ff..8c7b4e3 100644
--- a/fw/app/src/settings.h
+++ b/fw/app/src/settings.h
@@ -12,6 +12,7 @@
 #include <zephyr/data/json.h>
 
 #define IPV6_STRLEN_MAX 39  // excluding '\0'
+#define SETTINGS_JSON_MAX_LEN (IPV6_STRLEN_MAX + 50)
 
 
 struct settings_syslog_target {