diff --git a/include/applet/adguard.h b/include/applet/adguard.h
index c904eb3..060a152 100644
--- a/include/applet/adguard.h
+++ b/include/applet/adguard.h
@@ -1,5 +1,5 @@
-#ifndef _ADGUARD_H_
-#define _ADGUARD_H_
+#ifndef ADGUARD_H_
+#define ADGUARD_H_
 
 #include <stdint.h>
 #include "process.h"
diff --git a/include/applet/dnsproxy.h b/include/applet/dnsproxy.h
index 68eb67c..564d320 100644
--- a/include/applet/dnsproxy.h
+++ b/include/applet/dnsproxy.h
@@ -1,5 +1,5 @@
-#ifndef _DNSPROXY_H_
-#define _DNSPROXY_H_
+#ifndef DNSPROXY_H_
+#define DNSPROXY_H_
 
 #include <stdint.h>
 #include "process.h"
diff --git a/include/applet/overture.h b/include/applet/overture.h
index 476942a..beb8646 100644
--- a/include/applet/overture.h
+++ b/include/applet/overture.h
@@ -1,5 +1,5 @@
-#ifndef _OVERTURE_H_
-#define _OVERTURE_H_
+#ifndef OVERTURE_H_
+#define OVERTURE_H_
 
 #include <stdint.h>
 #include "process.h"
diff --git a/include/common/constant.h b/include/common/constant.h
index 16d6ace..bbcc630 100644
--- a/include/common/constant.h
+++ b/include/common/constant.h
@@ -1,5 +1,5 @@
-#ifndef _CONSTANT_H_
-#define _CONSTANT_H_
+#ifndef CONSTANT_H_
+#define CONSTANT_H_
 
 #define VERSION "1.3.0-dev"
 
diff --git a/include/common/json.h b/include/common/json.h
index 45929ae..054c03c 100644
--- a/include/common/json.h
+++ b/include/common/json.h
@@ -1,5 +1,5 @@
-#ifndef _JSON_H_
-#define _JSON_H_
+#ifndef JSON_H_
+#define JSON_H_
 
 #include <stdint.h>
 #include "cJSON.h"
diff --git a/include/common/structure.h b/include/common/structure.h
index 403844c..ccc77ba 100644
--- a/include/common/structure.h
+++ b/include/common/structure.h
@@ -1,5 +1,5 @@
-#ifndef _STRUCTURE_H_
-#define _STRUCTURE_H_
+#ifndef STRUCTURE_H_
+#define STRUCTURE_H_
 
 #include <stdint.h>
 
diff --git a/include/common/sundry.h b/include/common/sundry.h
index 621470b..c10542d 100644
--- a/include/common/sundry.h
+++ b/include/common/sundry.h
@@ -1,5 +1,5 @@
-#ifndef _SUNDRY_H_
-#define _SUNDRY_H_
+#ifndef SUNDRY_H_
+#define SUNDRY_H_
 
 #include <stdint.h>
 
diff --git a/include/common/system.h b/include/common/system.h
index a6325bc..0404664 100644
--- a/include/common/system.h
+++ b/include/common/system.h
@@ -1,14 +1,14 @@
-#ifndef _SYSTEM_H_
-#define _SYSTEM_H_
+#ifndef SYSTEM_H_
+#define SYSTEM_H_
 
 #include <stdint.h>
 
 char* read_file(const char *file);
+void remove_file(const char *file);
 int run_command(const char *command);
 void create_folder(const char *folder);
 uint8_t is_file_exist(const char *file);
 void save_file(const char *file, const char *content);
 void save_string_list(const char *file, char **string_list);
 
-
 #endif
diff --git a/include/flag.h b/include/flag.h
deleted file mode 100644
index dc0cf2c..0000000
--- a/include/flag.h
+++ /dev/null
@@ -1,18 +0,0 @@
-#ifndef _EXIT_CODE_H_
-#define _EXIT_CODE_H_
-
-#ifndef TRUE
-#define TRUE 1
-#endif
-
-#ifndef FALSE
-#define FALSE 0
-#endif
-
-#define EXIT_NORMAL 0
-#define EXIT_FILE_ERROR 1
-#define EXIT_FORK_ERROR 2
-#define EXIT_EXEC_ERROR 3
-#define EXIT_WAIT_ERROR 4
-
-#endif
diff --git a/include/loader/config.h b/include/loader/config.h
index de1f2d0..b14e3e2 100644
--- a/include/loader/config.h
+++ b/include/loader/config.h
@@ -1,5 +1,5 @@
-#ifndef _CONFIG_H_
-#define _CONFIG_H_
+#ifndef CONFIG_H_
+#define CONFIG_H_
 
 #include <stdint.h>
 
diff --git a/include/loader/loader.h b/include/loader/loader.h
index 5b01f08..3f5f359 100644
--- a/include/loader/loader.h
+++ b/include/loader/loader.h
@@ -1,5 +1,5 @@
-#ifndef _LOADER_H_
-#define _LOADER_H_
+#ifndef LOADER_H_
+#define LOADER_H_
 
 #include "adguard.h"
 #include "dnsproxy.h"
diff --git a/include/loader/parser.h b/include/loader/parser.h
index de25ad7..15a02de 100644
--- a/include/loader/parser.h
+++ b/include/loader/parser.h
@@ -1,5 +1,5 @@
-#ifndef _PARSER_H_
-#define _PARSER_H_
+#ifndef PARSER_H_
+#define PARSER_H_
 
 #include "config.h"
 
diff --git a/include/utils/logger.h b/include/utils/logger.h
index 66c8b42..59ca40f 100644
--- a/include/utils/logger.h
+++ b/include/utils/logger.h
@@ -1,5 +1,5 @@
-#ifndef _LOGGER_H_
-#define _LOGGER_H_
+#ifndef LOGGER_H_
+#define LOGGER_H_
 
 #define LOG_PREFIX "ClearDNS"
 
diff --git a/include/utils/process.h b/include/utils/process.h
index ce9d8c5..b4b5969 100644
--- a/include/utils/process.h
+++ b/include/utils/process.h
@@ -1,5 +1,5 @@
-#ifndef _PROCESS_H_
-#define _PROCESS_H_
+#ifndef PROCESS_H_
+#define PROCESS_H_
 
 typedef struct {
     char *name;
diff --git a/src/applet/adguard.c b/src/applet/adguard.c
index 38470c6..3b7aeb6 100644
--- a/src/applet/adguard.c
+++ b/src/applet/adguard.c
@@ -1,4 +1,5 @@
 #include <stdlib.h>
+#include <string.h>
 #include "json.h"
 #include "bcrypt.h"
 #include "logger.h"
@@ -76,6 +77,12 @@ process* adguard_load(adguard *info, const char *dir) { // load adguard options
     if (!check_port(info->web_port)) { // invalid web port
         log_fatal("Invalid web port `%u`", info->web_port);
     }
+    if (!strcmp(info->username, "")) { // invalid username
+        log_fatal("Invalid AdGuardHome username");
+    }
+    if (!strcmp(info->password, "")) { // invalid password
+        log_fatal("Invalid AdGuardHome password");
+    }
 
     create_folder(dir); // ensure adguard work dir exist
     char *adguard_config_ret;
diff --git a/src/cleardns.c b/src/cleardns.c
index 1995dd9..0626768 100644
--- a/src/cleardns.c
+++ b/src/cleardns.c
@@ -42,15 +42,6 @@ int main(int argc, char *argv[]) { // ClearDNS server
     LOG_LEVEL = LOG_DEBUG;
     log_info("ClearDNS server start (%s)", VERSION);
 
-//    if (is_file_exist("/tmp/test")) {
-//        log_info("File exist");
-//    }
-
-//    create_folder("/tmp/test");
-//    run_command("exit 3");
-    run_command("exit");
-
-    return 0;
 
 //    char **temp = string_list_init();
 //
diff --git a/src/common/json.c b/src/common/json.c
index a4cc53f..623958d 100644
--- a/src/common/json.c
+++ b/src/common/json.c
@@ -26,20 +26,17 @@ char* to_json(const char *file) { // convert JSON / TOML / YAML to json format (
     }
     flag[8] = '\0';
 
-    char *output_file = string_join("/tmp/tojson-", flag);
+    char *output_file = string_join("/tmp/to-json-", flag);
     char *to_json_cmd = (char *)malloc(strlen(file) + strlen(output_file) + 11);
     sprintf(to_json_cmd, "toJSON %s > %s", file, output_file);
     int to_json_ret = run_command(to_json_cmd);
     free(to_json_cmd);
 
-    char *remove_cmd = string_join("rm -f ", output_file);
-    run_command(remove_cmd);
-    free(remove_cmd);
-    if (to_json_ret) { // toJSON return non-zero code
-        free(output_file);
-        return NULL; // convert failed
+    char *json_content = NULL;
+    if (!to_json_ret) { // toJSON return zero code (convert fine)
+        json_content = read_file(output_file);
     }
-    char *json_content = read_file(output_file);
+    remove_file(output_file);
     free(output_file);
     return json_content;
 }
diff --git a/src/common/system.c b/src/common/system.c
index 9de03f0..aa318ef 100644
--- a/src/common/system.c
+++ b/src/common/system.c
@@ -15,6 +15,12 @@ int run_command(const char *command) { // running command with system shell
     return ret;
 }
 
+void remove_file(const char *file) {
+    char *remove_cmd = string_join("rm -f ", file);
+    run_command(remove_cmd);
+    free(remove_cmd);
+}
+
 void create_folder(const char *folder) { // create folder
     if (!access(folder, 0)) { // target is file or folder
         struct stat buf;
diff --git a/src/common_legacy.c b/src/common_legacy.c
index ae9d59e..e27044e 100644
--- a/src/common_legacy.c
+++ b/src/common_legacy.c
@@ -2,7 +2,7 @@
 #include <stdlib.h>
 #include <strList.bak>
 #include "cJSON.h"
-#include "flag.h"
+#include "flag_legacy.h"
 
 char **adguard_command = NULL;
 char **overture_command = NULL;
diff --git a/src/loader/loader.c b/src/loader/loader.c
index c134c99..6d9a946 100644
--- a/src/loader/loader.c
+++ b/src/loader/loader.c
@@ -94,8 +94,8 @@ adguard* load_filter(cleardns_config *config) {
     adguard *filter = adguard_init();
     filter->dns_port = config->port;
     filter->web_port = config->adguard.port;
-    filter->username = config->adguard.username;
-    filter->password = config->adguard.password;
+    filter->username = string_init(config->adguard.username);
+    filter->password = string_init(config->adguard.password);
     char *diverter_port = uint32_to_string(config->diverter.port);
     filter->upstream = string_join("127.0.0.1:", diverter_port);
     free(diverter_port);
diff --git a/src/process_legacy.c b/src/process_legacy.c
index c76c349..10757f3 100644
--- a/src/process_legacy.c
+++ b/src/process_legacy.c
@@ -7,7 +7,7 @@
 #include <sys/wait.h>
 #include <sys/prctl.h>
 #include "constant.h"
-#include "flag.h"
+#include "flag_legacy.h"
 
 int exiting = 0;