Support custom STUN servers configuration (#1212)

* Support custom STUN servers

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

easytier/src/instance/dns_server/system_config/windows.rs

@@ -39,7 +39,7 @@ impl InterfaceControl {
                 if matches!(e.kind(), io::ErrorKind::NotFound) {
                     Ok(()) // 忽略不存在的值
                 } else {
-                    Err(e.into())
+                    Err(e)
                 }
             }
         }
@@ -106,10 +106,7 @@ impl InterfaceControl {
             .output()
             .expect("failed to execute process");
         if !output.status.success() {
-            return Err(io::Error::new(
-                io::ErrorKind::Other,
-                "Failed to flush DNS cache",
-            ));
+            return Err(io::Error::other("Failed to flush DNS cache"));
         }
         Ok(())
     }
@@ -122,10 +119,7 @@ impl InterfaceControl {
             .output()
             .expect("failed to execute process");
         if !output.status.success() {
-            return Err(io::Error::new(
-                io::ErrorKind::Other,
-                "Failed to register DNS",
-            ));
+            return Err(io::Error::other("Failed to register DNS"));
         }
         Ok(())
     }

easytier/src/instance/virtual_nic.rs

@@ -399,7 +399,7 @@ impl VirtualNic {
                 Err(e) => {
                     println!("Failed to add Easytier to firewall allowlist, Subnet proxy and KCP proxy may not work properly. error: {}", e);
                     println!("You can add firewall rules manually, or use --use-smoltcp to run with user-space TCP/IP stack.");
-                    println!("");
+                    println!();
                 }
             }
 
@@ -409,7 +409,7 @@ impl VirtualNic {
             }
 
             if !dev_name.is_empty() {
-                config.tun_name(format!("{}", dev_name));
+                config.tun_name(&dev_name);
             } else {
                 use rand::distributions::Distribution as _;
                 let c = crate::arch::windows::interface_count()?;