refactor: update custom STUN server settings (#1310)

* refactor: update global context STUN server initialization

Modified global context initialization to use a single StunInfoCollector
instance with properly configured IPv4 and IPv6 servers instead of
creating separate instances.

feat: add IPv6 STUN server configuration support

Added interface methods and config struct fields to support both IPv4
and IPv6 STUN server configuration. Modified getter and setter methods
to handle Option<Vec<String>> type for both server types.

feat: enhance StunInfoCollector with IPv6 support

Updated StunInfoCollector to support both IPv4 and IPv6 STUN servers.
Added new constructor that accepts both server types and methods to set
them independently.

feat: add CLI argument for IPv6 STUN servers

Added command line argument support for configuring IPv6 STUN servers.
Updated configuration setup to handle both IPv4 and IPv6 STUN server
settings.

docs: add localization for STUN server configuration

Added English and Chinese localization strings for the new STUN server
configuration options, including both IPv4 and IPv6 variants.

easytier/src/common/config.rs

@@ -200,8 +200,11 @@ pub trait ConfigLoader: Send + Sync {
     fn get_udp_whitelist(&self) -> Vec<String>;
     fn set_udp_whitelist(&self, whitelist: Vec<String>);
 
-    fn get_stun_servers(&self) -> Vec<String>;
-    fn set_stun_servers(&self, servers: Vec<String>);
+    fn get_stun_servers(&self) -> Option<Vec<String>>;
+    fn set_stun_servers(&self, servers: Option<Vec<String>>);
+
+    fn get_stun_servers_v6(&self) -> Option<Vec<String>>;
+    fn set_stun_servers_v6(&self, servers: Option<Vec<String>>);
 
     fn dump(&self) -> String;
 }
@@ -374,7 +377,7 @@ impl From<PortForwardConfig> for PortForwardConfigPb {
     }
 }
 
-#[derive(Debug, Clone, Deserialize, Serialize, PartialEq)]
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 struct Config {
     netns: Option<String>,
     hostname: Option<String>,
@@ -412,6 +415,7 @@ struct Config {
     tcp_whitelist: Option<Vec<String>>,
     udp_whitelist: Option<Vec<String>>,
     stun_servers: Option<Vec<String>>,
+    stun_servers_v6: Option<Vec<String>>,
 }
 
 #[derive(Debug, Clone)]
@@ -791,17 +795,20 @@ impl ConfigLoader for TomlConfigLoader {
         self.config.lock().unwrap().udp_whitelist = Some(whitelist);
     }
 
-    fn get_stun_servers(&self) -> Vec<String> {
-        self.config
-            .lock()
-            .unwrap()
-            .stun_servers
-            .clone()
-            .unwrap_or_default()
+    fn get_stun_servers(&self) -> Option<Vec<String>> {
+        self.config.lock().unwrap().stun_servers.clone()
     }
 
-    fn set_stun_servers(&self, servers: Vec<String>) {
-        self.config.lock().unwrap().stun_servers = Some(servers);
+    fn set_stun_servers(&self, servers: Option<Vec<String>>) {
+        self.config.lock().unwrap().stun_servers = servers;
+    }
+
+    fn get_stun_servers_v6(&self) -> Option<Vec<String>> {
+        self.config.lock().unwrap().stun_servers_v6.clone()
+    }
+
+    fn set_stun_servers_v6(&self, servers: Option<Vec<String>>) {
+        self.config.lock().unwrap().stun_servers_v6 = servers;
     }
 
     fn dump(&self) -> String {
@@ -838,14 +845,14 @@ pub mod tests {
     fn test_stun_servers_config() {
         let config = TomlConfigLoader::default();
         let stun_servers = config.get_stun_servers();
-        assert!(stun_servers.is_empty());
+        assert!(stun_servers.is_none());
 
         // Test setting custom stun servers
         let custom_servers = vec!["txt:stun.easytier.cn".to_string()];
-        config.set_stun_servers(custom_servers.clone());
+        config.set_stun_servers(Some(custom_servers.clone()));
 
         let retrieved_servers = config.get_stun_servers();
-        assert_eq!(retrieved_servers, custom_servers);
+        assert_eq!(retrieved_servers.unwrap(), custom_servers);
     }
 
     #[test]
@@ -859,7 +866,7 @@ stun_servers = [
 ]"#;
 
         let config = TomlConfigLoader::new_from_str(config_str).unwrap();
-        let stun_servers = config.get_stun_servers();
+        let stun_servers = config.get_stun_servers().unwrap();
 
         assert_eq!(stun_servers.len(), 3);
         assert_eq!(stun_servers[0], "stun.l.google.com:19302");