diff --git a/dap-lib/src/client/doh_client_main.rs b/dap-lib/src/client/doh_client_main.rs
deleted file mode 100644
index d092e87..0000000
--- a/dap-lib/src/client/doh_client_main.rs
+++ /dev/null
@@ -1,21 +0,0 @@
-use crate::{error::*, globals::Globals, http_client::HttpClientInner};
-use std::sync::Arc;
-use tokio::sync::RwLock;
-
-#[derive(Debug)]
-/// DoH, ODoH, MODoH client
-pub struct DoHClient {
-  inner: Arc<RwLock<HttpClientInner>>,
-}
-
-impl DoHClient {
-  /// Create a new DoH client
-  pub fn new(inner: Arc<RwLock<HttpClientInner>>) -> Self {
-    Self { inner }
-  }
-
-  /// Make DoH query
-  pub async fn make_doh_query(&self, packet_buf: &[u8], globals: &Arc<Globals>) -> Result<Vec<u8>> {
-    Ok(vec![])
-  }
-}
diff --git a/dap-lib/src/client/mod.rs b/dap-lib/src/client/mod.rs
deleted file mode 100644
index 91e4cbc..0000000
--- a/dap-lib/src/client/mod.rs
+++ /dev/null
@@ -1,9 +0,0 @@
-mod doh_client_main;
-
-pub use doh_client_main::DoHClient;
-
-#[derive(PartialEq, Eq, Debug, Clone)]
-pub enum DoHMethod {
-  Get,
-  Post,
-}
diff --git a/dap-lib/src/constants.rs b/dap-lib/src/constants.rs
index cee00ec..89fe2c3 100644
--- a/dap-lib/src/constants.rs
+++ b/dap-lib/src/constants.rs
@@ -39,8 +39,9 @@ pub const TOKEN_REFRESH_MARGIN: i64 = 120;
 /// every 60 secs, token is checked. then if the refresh condition is satisfied, refresh.
 /// this is to rapidly recover from the hibernation of PC on which this is working. (at most 60 secs is needed for recovery)
 pub const TOKEN_REFRESH_WATCH_DELAY: i64 = 60;
-
+/// wait for 10 secs before relogin
 pub const TOKEN_RELOGIN_WAITING_SEC: u64 = 10;
+/// relogin at most 5 times
 pub const MAX_RELOGIN_ATTEMPTS: usize = 5;
 
 pub const HEALTHCHECK_TARGET_FQDN: &str = "dns.google."; // client