ME Probe + STUN Legacy

src/config/load.rs

@@ -131,6 +131,9 @@ impl ProxyConfig {
         let general_table = parsed_toml
             .get("general")
             .and_then(|value| value.as_table());
+        let network_table = parsed_toml
+            .get("network")
+            .and_then(|value| value.as_table());
         let update_every_is_explicit = general_table
             .map(|table| table.contains_key("update_every"))
             .unwrap_or(false);
@@ -140,6 +143,9 @@ impl ProxyConfig {
         let legacy_config_is_explicit = general_table
             .map(|table| table.contains_key("proxy_config_auto_reload_secs"))
             .unwrap_or(false);
+        let stun_servers_is_explicit = network_table
+            .map(|table| table.contains_key("stun_servers"))
+            .unwrap_or(false);
 
         let mut config: ProxyConfig =
             parsed_toml.try_into().map_err(|e| ProxyError::Config(e.to_string()))?;
@@ -151,11 +157,19 @@ impl ProxyConfig {
         let legacy_nat_stun = config.general.middle_proxy_nat_stun.take();
         let legacy_nat_stun_servers = std::mem::take(&mut config.general.middle_proxy_nat_stun_servers);
         let legacy_nat_stun_used = legacy_nat_stun.is_some() || !legacy_nat_stun_servers.is_empty();
-
+        if stun_servers_is_explicit {
-        let mut unified_stun_servers = Vec::new();
+            let mut explicit_stun_servers = Vec::new();
             for stun in std::mem::take(&mut config.network.stun_servers) {
-            push_unique_nonempty(&mut unified_stun_servers, stun);
+                push_unique_nonempty(&mut explicit_stun_servers, stun);
             }
+            config.network.stun_servers = explicit_stun_servers;
+
+            if legacy_nat_stun_used {
+                warn!("general.middle_proxy_nat_stun and general.middle_proxy_nat_stun_servers are ignored because network.stun_servers is explicitly set");
+            }
+        } else {
+            // Keep the default STUN pool unless network.stun_servers is explicitly overridden.
+            let mut unified_stun_servers = default_stun_servers();
             if let Some(stun) = legacy_nat_stun {
                 push_unique_nonempty(&mut unified_stun_servers, stun);
             }
@@ -163,14 +177,12 @@ impl ProxyConfig {
                 push_unique_nonempty(&mut unified_stun_servers, stun);
             }
 
-        if unified_stun_servers.is_empty() {
-            unified_stun_servers = default_stun_servers();
-        }
             config.network.stun_servers = unified_stun_servers;
 
             if legacy_nat_stun_used {
                 warn!("general.middle_proxy_nat_stun and general.middle_proxy_nat_stun_servers are deprecated; use network.stun_servers");
             }
+        }
 
         if let Some(update_every) = config.general.update_every {
             if update_every == 0 {

src/transport/middle_proxy/pool.rs

@@ -1200,15 +1200,23 @@ impl MePool {
         }
         addrs.shuffle(&mut rand::rng());
         if addrs.len() > 1 {
+            let concurrency = 2usize;
             let mut join = tokio::task::JoinSet::new();
-            for (ip, port) in addrs {
+            let mut next_idx = 0usize;
+
+            while next_idx < addrs.len() || !join.is_empty() {
+                while next_idx < addrs.len() && join.len() < concurrency {
+                    let (ip, port) = addrs[next_idx];
+                    next_idx += 1;
                     let addr = SocketAddr::new(ip, port);
                     let pool = Arc::clone(&self);
                     let rng_clone = Arc::clone(&rng);
                     join.spawn(async move { (addr, pool.connect_one(addr, rng_clone.as_ref()).await) });
                 }
 
-            while let Some(res) = join.join_next().await {
+                let Some(res) = join.join_next().await else {
+                    break;
+                };
                 match res {
                     Ok((addr, Ok(()))) => {
                         info!(%addr, dc = %dc, "ME connected");