diff --git a/bin/ssurl.rs b/bin/ssurl.rs
index c94fbaa7..bdba3708 100644
--- a/bin/ssurl.rs
+++ b/bin/ssurl.rs
@@ -158,5 +158,5 @@ fn main() -> ExitCode {
     }
 
     println!("Use -h for more detail");
-    return ExitCode::FAILURE;
+    ExitCode::FAILURE
 }
diff --git a/crates/shadowsocks-service/src/local/http/http_client.rs b/crates/shadowsocks-service/src/local/http/http_client.rs
index b2c13151..784b7d29 100644
--- a/crates/shadowsocks-service/src/local/http/http_client.rs
+++ b/crates/shadowsocks-service/src/local/http/http_client.rs
@@ -39,6 +39,7 @@ pub enum HttpClientError {
 
 #[derive(Clone)]
 pub struct HttpClient {
+    #[allow(clippy::type_complexity)]
     cache_conn: Arc<Mutex<LruCache<Address, VecDeque<(HttpConnection, Instant)>>>>,
 }
 
@@ -96,7 +97,7 @@ impl HttpClient {
     }
 
     async fn get_cached_connection(&self, host: &Address) -> Option<HttpConnection> {
-        if let Some(q) = self.cache_conn.lock().await.get_mut(&host) {
+        if let Some(q) = self.cache_conn.lock().await.get_mut(host) {
             while let Some((c, inst)) = q.pop_front() {
                 let now = Instant::now();
                 if now - inst >= CONNECTION_EXPIRE_DURATION {
diff --git a/crates/shadowsocks-service/src/local/redir/sys/unix/bsd_pf.rs b/crates/shadowsocks-service/src/local/redir/sys/unix/bsd_pf.rs
index 61b08c9c..b7782079 100644
--- a/crates/shadowsocks-service/src/local/redir/sys/unix/bsd_pf.rs
+++ b/crates/shadowsocks-service/src/local/redir/sys/unix/bsd_pf.rs
@@ -61,7 +61,7 @@ impl PacketFilter {
         match proto {
             Protocol::TCP => self.tcp_natlook(bind_addr, peer_addr, proto),
             Protocol::UDP => self.udp_natlook(bind_addr, peer_addr, proto),
-            _ => return Err(io::ErrorKind::InvalidInput.into()),
+            _ => Err(io::ErrorKind::InvalidInput.into()),
         }
     }
 
@@ -81,12 +81,7 @@ impl PacketFilter {
                     let addr: *const in_addr = ptr::addr_of!((*sockaddr).sin_addr) as *const _;
                     let port: libc::in_port_t = (*sockaddr).sin_port;
 
-                    #[allow(clippy::size_of_in_element_count)]
-                    ptr::copy_nonoverlapping(
-                        addr,
-                        ptr::addr_of_mut!(pnl.daddr.pfa) as *mut _,
-                        mem::size_of::<in_addr>(),
-                    );
+                    ptr::write_unaligned::<in_addr>(ptr::addr_of_mut!(pnl.daddr.pfa) as *mut _, *addr);
 
                     cfg_if! {
                         if #[cfg(any(target_os = "macos", target_os = "ios"))] {
@@ -105,12 +100,7 @@ impl PacketFilter {
                     let addr: *const in6_addr = ptr::addr_of!((*sockaddr).sin6_addr) as *const _;
                     let port: libc::in_port_t = (*sockaddr).sin6_port;
 
-                    #[allow(clippy::size_of_in_element_count)]
-                    ptr::copy_nonoverlapping(
-                        addr,
-                        ptr::addr_of_mut!(pnl.daddr.pfa) as *mut _,
-                        mem::size_of::<in6_addr>(),
-                    );
+                    ptr::write_unaligned::<in6_addr>(ptr::addr_of_mut!(pnl.daddr.pfa) as *mut _, *addr);
 
                     cfg_if! {
                         if #[cfg(any(target_os = "macos", target_os = "ios"))] {
@@ -134,12 +124,7 @@ impl PacketFilter {
                     let addr: *const in_addr = ptr::addr_of!((*sockaddr).sin_addr) as *const _;
                     let port: libc::in_port_t = (*sockaddr).sin_port;
 
-                    #[allow(clippy::size_of_in_element_count)]
-                    ptr::copy_nonoverlapping(
-                        addr,
-                        ptr::addr_of_mut!(pnl.saddr.pfa) as *mut _,
-                        mem::size_of::<in_addr>(),
-                    );
+                    ptr::write_unaligned::<in_addr>(ptr::addr_of_mut!(pnl.saddr.pfa) as *mut _, *addr);
 
                     cfg_if! {
                         if #[cfg(any(target_os = "macos", target_os = "ios"))] {
@@ -160,12 +145,7 @@ impl PacketFilter {
                     let addr: *const in6_addr = ptr::addr_of!((*sockaddr).sin6_addr) as *const _;
                     let port: libc::in_port_t = (*sockaddr).sin6_port;
 
-                    #[allow(clippy::size_of_in_element_count)]
-                    ptr::copy_nonoverlapping(
-                        addr,
-                        ptr::addr_of_mut!(pnl.saddr.pfa) as *mut _,
-                        mem::size_of::<in6_addr>(),
-                    );
+                    ptr::write_unaligned::<in6_addr>(ptr::addr_of_mut!(pnl.saddr.pfa) as *mut _, *addr);
 
                     cfg_if! {
                         if #[cfg(any(target_os = "macos", target_os = "ios"))] {
@@ -197,11 +177,9 @@ impl PacketFilter {
                         }
                     }
 
-                    #[allow(clippy::size_of_in_element_count)]
-                    ptr::copy_nonoverlapping(
-                        ptr::addr_of!(pnl.rdaddr.pfa) as *const _,
+                    ptr::write_unaligned::<in_addr>(
                         ptr::addr_of_mut!(dst_addr.sin_addr),
-                        mem::size_of_val(&dst_addr.sin_addr),
+                        ptr::read::<in_addr>(ptr::addr_of!(pnl.rdaddr.pfa) as *const _),
                     );
                     *addr_len = mem::size_of_val(&dst_addr.sin_addr) as libc::socklen_t;
                 } else if pnl.af == libc::AF_INET6 as libc::sa_family_t {
@@ -216,11 +194,9 @@ impl PacketFilter {
                         }
                     }
 
-                    #[allow(clippy::size_of_in_element_count)]
-                    ptr::copy_nonoverlapping(
-                        ptr::addr_of!(pnl.rdaddr.pfa) as *const _,
+                    ptr::write_unaligned::<in6_addr>(
                         ptr::addr_of_mut!(dst_addr.sin6_addr),
-                        mem::size_of_val(&dst_addr.sin6_addr),
+                        ptr::read::<in6_addr>(ptr::addr_of!(pnl.rdaddr.pfa) as *const _),
                     );
                     *addr_len = mem::size_of_val(&dst_addr.sin6_addr) as libc::socklen_t;
                 } else {
@@ -270,18 +246,16 @@ impl PacketFilter {
             match bind_addr_sockaddr.family() as libc::c_int {
                 libc::AF_INET => {
                     let sockaddr: *const sockaddr_in = bind_addr_sockaddr.as_ptr() as *const _;
-                    ptr::copy_nonoverlapping(
-                        ptr::addr_of!((&*sockaddr).sin_addr),
+                    ptr::write_unaligned::<in_addr>(
                         ptr::addr_of_mut!(bind_addr_pfaddr.pfa) as *mut _,
-                        mem::size_of::<in_addr>(),
+                        (*sockaddr).sin_addr,
                     );
                 }
                 libc::AF_INET6 => {
                     let sockaddr: *const sockaddr_in6 = bind_addr_sockaddr.as_ptr() as *const _;
-                    ptr::copy_nonoverlapping(
-                        ptr::addr_of!((&*sockaddr).sin6_addr),
+                    ptr::write_unaligned::<in6_addr>(
                         ptr::addr_of_mut!(bind_addr_pfaddr.pfa) as *mut _,
-                        mem::size_of::<in6_addr>(),
+                        (*sockaddr).sin6_addr,
                     );
                 }
                 _ => unreachable!("bind_addr family = {}", bind_addr_sockaddr.family()),
@@ -290,18 +264,16 @@ impl PacketFilter {
             match peer_addr_sockaddr.family() as libc::c_int {
                 libc::AF_INET => {
                     let sockaddr: *const sockaddr_in = peer_addr_sockaddr.as_ptr() as *const _;
-                    ptr::copy_nonoverlapping(
-                        ptr::addr_of!((&*sockaddr).sin_addr),
+                    ptr::write_unaligned::<in_addr>(
                         ptr::addr_of_mut!(peer_addr_pfaddr.pfa) as *mut _,
-                        mem::size_of::<in_addr>(),
+                        (*sockaddr).sin_addr,
                     );
                 }
                 libc::AF_INET6 => {
                     let sockaddr: *const sockaddr_in6 = peer_addr_sockaddr.as_ptr() as *const _;
-                    ptr::copy_nonoverlapping(
-                        ptr::addr_of!((&*sockaddr).sin6_addr),
+                    ptr::write_unaligned::<in6_addr>(
                         ptr::addr_of_mut!(peer_addr_pfaddr.pfa) as *mut _,
-                        mem::size_of::<in6_addr>(),
+                        (*sockaddr).sin6_addr,
                     );
                 }
                 _ => unreachable!("peer_addr family = {}", peer_addr_sockaddr.family()),
@@ -341,10 +313,9 @@ impl PacketFilter {
                                 let (_, actual_dst_addr) = SockAddr::try_init(|sockaddr, len| {
                                     let addr = &mut *(sockaddr as *mut sockaddr_in);
                                     addr.sin_family = libc::AF_INET as libc::sa_family_t;
-                                    ptr::copy_nonoverlapping(
-                                        ptr::addr_of!(state.gwy.addr.pfa) as *const _,
+                                    ptr::write_unaligned::<in_addr>(
                                         ptr::addr_of_mut!(addr.sin_addr),
-                                        mem::size_of::<in_addr>(),
+                                        ptr::read_unaligned::<in_addr>(ptr::addr_of!(state.gwy.addr.pfa) as *const _),
                                     );
                                     addr.sin_port = actual_dst_port as libc::in_port_t;
 
@@ -359,10 +330,9 @@ impl PacketFilter {
                                 let (_, actual_dst_addr) = SockAddr::try_init(|sockaddr, len| {
                                     let addr = &mut *(sockaddr as *mut sockaddr_in6);
                                     addr.sin6_family = libc::AF_INET6 as libc::sa_family_t;
-                                    ptr::copy_nonoverlapping(
-                                        ptr::addr_of!(state.gwy.addr.pfa) as *const _,
+                                    ptr::write_unaligned::<in6_addr>(
                                         ptr::addr_of_mut!(addr.sin6_addr),
-                                        mem::size_of::<in6_addr>(),
+                                        ptr::read_unaligned::<in6_addr>(ptr::addr_of!(state.gwy.addr.pfa) as *const _),
                                     );
                                     addr.sin6_port = actual_dst_port as libc::in_port_t;
 
diff --git a/crates/shadowsocks-service/src/local/redir/sys/unix/mod.rs b/crates/shadowsocks-service/src/local/redir/sys/unix/mod.rs
index fa9bc724..7a080386 100644
--- a/crates/shadowsocks-service/src/local/redir/sys/unix/mod.rs
+++ b/crates/shadowsocks-service/src/local/redir/sys/unix/mod.rs
@@ -13,10 +13,12 @@ cfg_if! {
                  target_os = "ios"))] {
         #[path = "pfvar_bindgen_macos.rs"]
         #[allow(dead_code, non_upper_case_globals, non_snake_case, non_camel_case_types)]
+        #[allow(clippy::useless_transmute)]
         mod pfvar;
     } else if #[cfg(target_os = "freebsd")] {
         #[path = "pfvar_bindgen_freebsd.rs"]
         #[allow(dead_code, non_upper_case_globals, non_snake_case, non_camel_case_types)]
+        #[allow(clippy::useless_transmute)]
         mod pfvar;
     }
 }
diff --git a/crates/shadowsocks-service/src/manager/server.rs b/crates/shadowsocks-service/src/manager/server.rs
index f281ef9c..6b16035d 100644
--- a/crates/shadowsocks-service/src/manager/server.rs
+++ b/crates/shadowsocks-service/src/manager/server.rs
@@ -417,7 +417,12 @@ impl Manager {
 
         let config_file_content = format!("{config}");
 
-        match OpenOptions::new().write(true).create(true).open(&config_file_path) {
+        match OpenOptions::new()
+            .write(true)
+            .create(true)
+            .truncate(true)
+            .open(&config_file_path)
+        {
             Err(err) => {
                 error!(
                     "failed to open {} for writing, error: {}",
diff --git a/crates/shadowsocks-service/src/sys/unix/macos.rs b/crates/shadowsocks-service/src/sys/unix/macos.rs
index 0e887d65..71f36283 100644
--- a/crates/shadowsocks-service/src/sys/unix/macos.rs
+++ b/crates/shadowsocks-service/src/sys/unix/macos.rs
@@ -59,7 +59,7 @@ pub fn get_launch_activate_socket(name: &str) -> io::Result<RawFd> {
     } else if cnt > 1 {
         for idx in 0..cnt {
             unsafe {
-                let fd = *(fds.offset(idx as isize));
+                let fd = *(fds.add(idx));
                 let _ = libc::close(fd);
             }
         }
diff --git a/crates/shadowsocks/src/config.rs b/crates/shadowsocks/src/config.rs
index 110781fa..50800982 100644
--- a/crates/shadowsocks/src/config.rs
+++ b/crates/shadowsocks/src/config.rs
@@ -633,7 +633,7 @@ impl ServerConfig {
             if #[cfg(feature = "aead-cipher-2022")] {
                 let user_info = if !self.method().is_aead_2022() {
                     let user_info = format!("{}:{}", self.method(), self.password());
-                    URL_PASSWORD_BASE64_ENGINE.encode(&user_info)
+                    URL_PASSWORD_BASE64_ENGINE.encode(user_info)
                 } else {
                     format!("{}:{}", self.method(), percent_encoding::utf8_percent_encode(self.password(), percent_encoding::NON_ALPHANUMERIC))
                 };
diff --git a/crates/shadowsocks/src/net/udp.rs b/crates/shadowsocks/src/net/udp.rs
index 18284347..55fbc011 100644
--- a/crates/shadowsocks/src/net/udp.rs
+++ b/crates/shadowsocks/src/net/udp.rs
@@ -204,7 +204,7 @@ impl UdpSocket {
         // Check MTU
         if let Some(mtu) = self.mtu {
             if buf.len() > mtu {
-                return Err(make_mtu_error(buf.len(), mtu)).into();
+                return Err(make_mtu_error(buf.len(), mtu));
             }
         }
 
@@ -229,7 +229,7 @@ impl UdpSocket {
         // Check MTU
         if let Some(mtu) = self.mtu {
             if buf.len() > mtu {
-                return Err(make_mtu_error(buf.len(), mtu)).into();
+                return Err(make_mtu_error(buf.len(), mtu));
             }
         }
 
diff --git a/src/logging/mod.rs b/src/logging/mod.rs
index b1d0692c..3973e569 100644
--- a/src/logging/mod.rs
+++ b/src/logging/mod.rs
@@ -55,7 +55,7 @@ pub fn init_with_config(bin_name: &str, config: &LogConfig) {
     };
 
     let config = match debug_level {
-        0 | 1 | 2 | 3 => logging_builder
+        0..=3 => logging_builder
             .logger(Logger::builder().build(bin_name, l1))
             .logger(Logger::builder().build("shadowsocks_rust", l1))
             .logger(Logger::builder().build("shadowsocks", l1))