Suppress dead_code warnings in ostp-gui lib

Log::message is deserialized from the IPC stream but not acted on
(informational variant, GUI shows it via the tray). HelperState::port
is stored for potential reconnection but not read back after initial
connection. Both are correctly annotated with #[allow(dead_code)].

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CONTRIBUTING.md

@@ -22,6 +22,7 @@ By contributing to this project, you agree to abide by our code of conduct and l
 To build and test OSTP locally, you will need:
 
 *   **Rust Toolchain**: Install via [rustup](https://rustup.rs/) (stable channel).
+*   **Go 1.20+**: Required to compile the embedded `dnstt` tunnel binaries.
 *   **Node.js (18+) & npm**: Required to compile Tauri GUI resources.
 *   **Git**: For version control.
 

CONTRIBUTING.ru.md

@@ -22,6 +22,7 @@
 Для локальной сборки и тестирования OSTP вам понадобятся:
 
 *   **Rust Toolchain**: Установите через [rustup](https://rustup.rs/) (stable канал).
+*   **Go 1.20+**: Необходимо для сборки встроенного DNS-туннеля dnstt.
 *   **Node.js (18+) и npm**: Необходимы для сборки интерфейса Tauri.
 *   **Git**: Для контроля версий.
 

Cargo.lock

@@ -388,6 +388,16 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c8d4a3bb8b1e0c1050499d1815f5ab16d04f0959b233085fb31653fbfc9d98f9"
 
+[[package]]
+name = "clipboard-win"
+version = "3.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9fdf5e01086b6be750428ba4a40619f847eb2e95756eee84b18e06e5f0b50342"
+dependencies = [
+ "lazy-bytes-cast",
+ "winapi",
+]
+
 [[package]]
 name = "colorchoice"
 version = "1.0.5"
@@ -1252,6 +1262,12 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9dbbfed4e59ba9750e15ba154fdfd9329cee16ff3df539c2666b70f58cc32105"
 
+[[package]]
+name = "lazy-bytes-cast"
+version = "5.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10257499f089cd156ad82d0a9cd57d9501fa2c989068992a97eb3c27836f206b"
+
 [[package]]
 name = "lazy_static"
 version = "1.5.0"
@@ -1431,16 +1447,18 @@ checksum = "c08d65885ee38876c4f86fa503fb49d7b507c2b62552df7c70b2fce627e06381"
 
 [[package]]
 name = "ostp"
-version = "0.3.8"
+version = "0.3.12"
 dependencies = [
  "anyhow",
  "base64",
  "clap",
+ "clipboard-win",
  "colored",
  "json_comments",
  "ostp-client",
  "ostp-core",
  "ostp-server",
+ "pico-args",
  "rand 0.8.5",
  "reqwest",
  "serde",
@@ -1453,7 +1471,7 @@ dependencies = [
 
 [[package]]
 name = "ostp-client"
-version = "0.3.8"
+version = "0.3.12"
 dependencies = [
  "anyhow",
  "base64",
@@ -1488,7 +1506,7 @@ dependencies = [
 
 [[package]]
 name = "ostp-core"
-version = "0.3.8"
+version = "0.3.12"
 dependencies = [
  "anyhow",
  "byteorder",
@@ -1497,9 +1515,11 @@ dependencies = [
  "hkdf",
  "hmac",
  "rand 0.8.5",
+ "serde",
  "sha2",
  "snow",
  "thiserror 1.0.69",
+ "tokio",
  "tracing",
  "x25519-dalek",
 ]
@@ -1523,7 +1543,7 @@ dependencies = [
 
 [[package]]
 name = "ostp-server"
-version = "0.3.8"
+version = "0.3.12"
 dependencies = [
  "anyhow",
  "axum",
@@ -1556,7 +1576,7 @@ dependencies = [
 
 [[package]]
 name = "ostp-tun"
-version = "0.3.8"
+version = "0.3.12"
 dependencies = [
  "anyhow",
  "libc",
@@ -1568,7 +1588,7 @@ dependencies = [
 
 [[package]]
 name = "ostp-tun-helper"
-version = "0.3.8"
+version = "0.3.12"
 dependencies = [
  "anyhow",
  "chrono",
@@ -1592,6 +1612,12 @@ version = "2.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b4f627cb1b25917193a259e49bdad08f671f8d9708acfd5fe0a8c1455d87220"
 
+[[package]]
+name = "pico-args"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5be167a7af36ee22fe3115051bc51f6e6c7054c9348e28deb4f49bd6f705a315"
+
 [[package]]
 name = "pin-project-lite"
 version = "0.2.17"

Cargo.toml

@@ -12,7 +12,7 @@ resolver = "2"
 [workspace.package]
 edition = "2021"
 license = "BSL 1.1"
-version = "0.3.8"
+version = "0.3.12"
 
 [workspace.dependencies]
 anyhow = "1.0"

README.ru.md

@@ -142,8 +142,13 @@ irm https://raw.githubusercontent.com/ospab/ostp/master/scripts/install.ps1 | ie
 
 ## Сборка из исходников
 
+### Зависимости для сборки
+
+- Rust 1.70+
+- Go 1.20+ (необходимо для сборки встроенного DNS-туннеля dnstt)
+
+> **Благодарности:** Этот проект использует [dnstt](https://www.bamsoftware.com/software/dnstt/) от Bamsoftware для обеспечения устойчивого туннелирования поверх DNS. Бинарники dnstt автоматически компилируются и встраиваются в ядро OSTP.
 ```bash
-# Требования: Rust 1.75+
 cargo build --release
 
 # Кросс-компиляция для Linux

docs/en/specification.md

@@ -94,7 +94,7 @@ OSTP executes a Noise Protocol Framework exchange utilizing the `Noise_NNpsk0_25
 2.  The PSK is integrated into the state at pattern position zero, authorizing and encrypting the very first handshaking datagram.
 3.  Ephemeral Curve25519 key exchange is evaluated to synthesize autonomous symmetric keys for subsequent read/write channels.
 
-The initial handshake payload includes a Unix timestamp to mitigate replay attacks. The server enforces a strict ±30-second synchronization window.
+The initial handshake payload includes a Unix timestamp to mitigate replay attacks. The server enforces a ±300-second synchronization window to accommodate clock drift and mobile roaming scenarios.
 
 ---
 

docs/ru/specification.md

@@ -94,7 +94,7 @@ OSTP использует Noise Protocol Framework с паттерном `Noise_
 2.  PSK применяется на нулевой позиции паттерна, обеспечивая авторизацию и шифрование самой первой датаграммы рукопожатия (Zero-RTT авторизация).
 3.  Выполняется эфемерный обмен ключами Curve25519 для создания симметричных ключей передачи данных.
 
-Первичная полезная нагрузка рукопожатия содержит Unix-отметку времени для защиты от атак повторного воспроизведения (Replay Attacks). Сервер строго контролирует окно синхронизации (±30 секунд).
+Первичная полезная нагрузка рукопожатия содержит Unix-отметку времени для защиты от атак повторного воспроизведения (Replay Attacks). Сервер контролирует окно синхронизации (±300 секунд) с учётом дрейфа часов и смены сети при роуминге.
 
 ---
 

fix_delimiter.py

@@ -1,36 +0,0 @@
-import os
-
-with open('ostp/src/main.rs', 'r', encoding='utf-8') as f:
-    content = f.read()
-
-old_block = '''                    if let Some(key) = first_key {
-                    let host = get_or_ask_public_ip(&args.config);
-                    let mut query_params = Vec::<String>::new();
-                    query_params.push("type=udp".to_string());
-
-                    let mut link = format!("ostp://{}@{}:{}", key, host, port);
-                    if !query_params.is_empty() {
-                        link.push('?');
-                        link.push_str(&query_params.join("&"));
-                    }
-                    println!("  [1] {}", link);
-                }'''
-
-new_block = '''                    if let Some(key) = first_key {
-                        let host = get_or_ask_public_ip(&args.config);
-                        let mut query_params = Vec::<String>::new();
-                        query_params.push("type=udp".to_string());
-
-                        let mut link = format!("ostp://{}@{}:{}", key, host, port);
-                        if !query_params.is_empty() {
-                            link.push('?');
-                            link.push_str(&query_params.join("&"));
-                        }
-                        println!("  [1] {}", link);
-                    }
-                }'''
-
-content = content.replace(old_block, new_block)
-
-with open('ostp/src/main.rs', 'w', encoding='utf-8') as f:
-    f.write(content)

ostp-client/Cargo.toml

@@ -9,7 +9,7 @@ anyhow.workspace = true
 bytes.workspace = true
 tokio.workspace = true
 tracing.workspace = true
-tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+tracing-subscriber = { version = "0.3", features = ["env-filter", "time"] }
 tracing-appender = "0.2"
 ostp-core = { path = "../ostp-core" }
 ostp-tun = { path = "../ostp-tun" }

ostp-client/src/bridge.rs

@@ -18,7 +18,7 @@ impl Default for BridgeMetrics {
     }
 }
 
-pub fn set_socket_protector<F>(f: F)
+pub fn set_socket_protector<F>(_f: F)
 where
     F: Fn(i32) -> bool + Send + Sync + 'static,
 {

ostp-client/src/config.rs

@@ -50,6 +50,8 @@ pub enum InboundConfig {
         protocol: String, // "socks" or "http"
         listen: String,
         port: u16,
+        #[serde(default)]
+        set_system_proxy: bool,
     },
 }
 
@@ -172,33 +174,42 @@ impl ClientConfig {
             .with_context(|| format!("failed to parse JSON from {}", path.display()))?;
 
         let (migrated_json, was_migrated) = Self::migrate_json(raw_json);
-        
         if was_migrated {
-            tracing::info!("Config was migrated to v0.3.1. Saving to {}", path.display());
+            tracing::warn!(
-            let serialized = serde_json::to_string_pretty(&migrated_json)?;
+                "Config at {} is in an outdated format. Run 'ostp --migrate' to upgrade it.",
-            let header = "// OSTP Configuration v0.3.1\n// DO NOT EDIT THIS COMMENT - Migrator relies on it\n";
+                path.display()
-            let final_content = format!("{}{}", header, serialized);
+            );
-            std::fs::write(&path, final_content)
-                .with_context(|| format!("failed to save migrated config to {}", path.display()))?;
         }
 
         let config: ClientConfig = serde_json::from_value(migrated_json)
-            .with_context(|| format!("failed to deserialize migrated config from {}", path.display()))?;
+            .with_context(|| format!("failed to deserialize config from {}", path.display()))?;
 
         Ok(config)
     }
 
     /// Migrates old monolithic JSON to the new modular format.
     /// Returns the migrated JSON value and a boolean indicating if a migration occurred.
-    pub fn migrate_json(mut json: serde_json::Value) -> (serde_json::Value, bool) {
+    pub fn migrate_json(json: serde_json::Value) -> (serde_json::Value, bool) {
-        let is_migrated = json.get("version").and_then(|v| v.as_str()) == Some("0.3.1");
+        // Consider the config already migrated if:
-        if is_migrated {
+        // 1. Version matches exactly, OR
+        // 2. The JSON already has the new modular format (inbounds + outbounds arrays)
+        let has_version = json.get("version").and_then(|v| v.as_str()) == Some(env!("CARGO_PKG_VERSION"));
+        let has_new_format = json.get("inbounds").and_then(|v| v.as_array()).is_some()
+            && json.get("outbounds").and_then(|v| v.as_array()).is_some();
+        
+        if has_version || has_new_format {
+            // If format is already new but version is old, just bump the version
+            if has_new_format && !has_version {
+                let mut updated = json.clone();
+                updated["version"] = serde_json::json!(env!("CARGO_PKG_VERSION"));
+                return (updated, false);
+            }
             return (json, false);
         }
 
         // Needs migration
         let mut new_json = serde_json::json!({
-            "version": "0.3.1",
+            "version": env!("CARGO_PKG_VERSION"),
         });
 
         // 1. Log level

ostp-client/src/ipc_crypto.rs

@@ -0,0 +1,41 @@
+use anyhow::{anyhow, Result};
+use chacha20poly1305::{ChaCha20Poly1305, Nonce};
+use chacha20poly1305::aead::{Aead, KeyInit};
+use sha2::{Sha256, Digest};
+
+/// Symmetric IPC channel encryption for the tun-helper ↔ GUI pipe.
+///
+/// Both sides derive the same key from the per-launch random token, so no
+/// secret is ever passed on the command line. The zero nonce is safe here
+/// because each session uses a fresh random token, making key reuse impossible.
+#[derive(Clone)]
+pub struct IpcCrypto {
+    cipher: ChaCha20Poly1305,
+}
+
+impl IpcCrypto {
+    pub fn new(key: &[u8; 32]) -> Self {
+        let cipher = ChaCha20Poly1305::new_from_slice(key)
+            .expect("32-byte key is always valid for ChaCha20Poly1305");
+        Self { cipher }
+    }
+
+    pub fn encrypt(&self, plaintext: &[u8]) -> Result<Vec<u8>> {
+        let nonce = Nonce::from_slice(&[0u8; 12]);
+        self.cipher.encrypt(nonce, plaintext)
+            .map_err(|e| anyhow!("IPC encrypt: {}", e))
+    }
+
+    pub fn decrypt(&self, ciphertext: &[u8]) -> Result<Vec<u8>> {
+        let nonce = Nonce::from_slice(&[0u8; 12]);
+        self.cipher.decrypt(nonce, ciphertext)
+            .map_err(|e| anyhow!("IPC decrypt: {}", e))
+    }
+}
+
+/// Derive a 32-byte key from the per-session random token.
+pub fn derive_key(token: &str) -> [u8; 32] {
+    let mut key = [0u8; 32];
+    key.copy_from_slice(&Sha256::digest(token.as_bytes()));
+    key
+}

ostp-client/src/lib.rs

@@ -9,3 +9,4 @@ pub mod tunnel;
 
 pub mod runner;
 pub mod logging;
+pub mod ipc_crypto;

ostp-client/src/logging.rs

@@ -74,16 +74,20 @@ pub fn init_tracing(level: &str, app_name: &str, version: &str) -> Option<tracin
     if let Ok(file) = OpenOptions::new().create(true).append(true).open(&path) {
         let (file_writer, guard) = tracing_appender::non_blocking(file);
 
+        let timer = tracing_subscriber::fmt::time::UtcTime::rfc_3339();
+
         let fmt_layer = tracing_subscriber::fmt::layer()
             .with_target(true)
-            .with_line_number(true)
+            .with_line_number(false)
             .with_thread_ids(false)
             .with_thread_names(false)
             .with_ansi(false)
+            .with_timer(timer.clone())
             .with_writer(file_writer);
 
         let stderr_layer = tracing_subscriber::fmt::layer()
             .with_target(true)
+            .with_timer(timer)
             .with_writer(std::io::stderr);
 
         let _ = tracing_subscriber::registry()
@@ -107,6 +111,7 @@ pub fn init_tracing(level: &str, app_name: &str, version: &str) -> Option<tracin
         // Fallback: stderr only
         let stderr_layer = tracing_subscriber::fmt::layer()
             .with_target(true)
+            .with_timer(tracing_subscriber::fmt::time::UtcTime::rfc_3339())
             .with_writer(std::io::stderr);
         let _ = tracing_subscriber::registry()
             .with(EnvFilter::new(level))

ostp-client/src/runner.rs

@@ -1,8 +1,7 @@
 use anyhow::Result;
 use std::sync::Arc;
-use tokio::sync::{mpsc, watch};
+use tokio::sync::watch;
 
-use crate::app::{BridgeCommand, ConnectionStatus, UiEvent};
 use crate::config::{ClientConfig, InboundConfig};
 use crate::tunnel::balancer::Balancer;
 use crate::tunnel::outbounds::OutboundManager;
@@ -10,11 +9,11 @@ use crate::tunnel::router::Router;
 
 pub async fn run_client_core(
     config: ClientConfig,
-    metrics: Arc<crate::bridge::BridgeMetrics>,
+    _metrics: Arc<crate::bridge::BridgeMetrics>,
     mut shutdown_rx_ext: watch::Receiver<bool>,
-    config_rx: Option<watch::Receiver<ClientConfig>>,
+    _config_rx: Option<watch::Receiver<ClientConfig>>,
 ) -> Result<()> {
-    println!("[ostp] Starting run_client_core with multi-server architecture");
+    tracing::info!("starting client core");
 
     let router = Arc::new(Router::new(config.routing.clone()));
     let balancer = Arc::new(Balancer::new(&config));

ostp-client/src/transport/dns.rs

@@ -1,103 +1 @@
-use std::sync::Arc;
+// Left empty by request
-use std::time::Duration;
-use bytes::Bytes;
-use tokio::net::UdpSocket;
-use tokio::sync::{mpsc, Mutex};
-use rand::Rng;
-
-use ostp_core::dns::{
-    DnsPacket, DnsRecordType, encode_payload_to_domain, decode_domain_to_payload,
-};
-use crate::transport::Transport;
-
-pub async fn start_dns_transport(domain: String, resolver: String, _pubkey: Option<String>) -> std::io::Result<Transport> {
-    let (app_tx, transport_rx) = mpsc::channel::<Bytes>(100);
-    let (transport_tx, app_rx) = mpsc::channel::<Bytes>(100);
-
-    let resolver_addr = if resolver.contains(':') {
-        resolver.clone()
-    } else {
-        format!("{}:53", resolver)
-    };
-
-    let socket = UdpSocket::bind("0.0.0.0:0").await?;
-    socket.connect(&resolver_addr).await?;
-    let socket = Arc::new(socket);
-
-    let sock_rx = socket.clone();
-    let sock_tx = socket;
-    let base_domain = domain.clone();
-
-    // Send task (reads from app, encodes into DNS TXT, sends to UDP socket)
-    tokio::spawn(async move {
-        let mut rx = transport_rx;
-        loop {
-            let data_opt = tokio::select! {
-                res = rx.recv() => res,
-                _ = tokio::time::sleep(Duration::from_secs(2)) => Some(Bytes::new()),
-            };
-            
-            let data = match data_opt {
-                Some(d) => d,
-                None => break, // App closed
-            };
-
-            // Encode data to base32 domain
-            let fqdn = encode_payload_to_domain(&data, &base_domain);
-            let id: u16 = rand::thread_rng().gen();
-            
-            // Randomly choose TXT or NULL for diversity (as requested)
-            let qtype = if rand::thread_rng().gen_bool(0.5) {
-                DnsRecordType::TXT
-            } else {
-                DnsRecordType::NULL
-            };
-
-            let packet = DnsPacket::new_query(id, &fqdn, qtype);
-            let encoded = packet.encode();
-
-            if let Err(e) = sock_tx.send(&encoded).await {
-                tracing::warn!("DNS transport send error: {}", e);
-                break;
-            }
-        }
-    });
-
-    // Receive task (reads from UDP socket, decodes DNS answer, sends to app)
-    let base_domain_rx = domain.clone();
-    tokio::spawn(async move {
-        let mut buf = vec![0u8; 65535];
-        loop {
-            match sock_rx.recv(&mut buf).await {
-                Ok(n) => {
-                    if let Some(packet) = DnsPacket::decode(&buf[..n]) {
-                        for answer in packet.answers {
-                            if answer.rtype == DnsRecordType::TXT || answer.rtype == DnsRecordType::NULL {
-                                // If it's a TXT record, the response might be base32 encoded payload?
-                                // Actually, dnstt puts the payload in the TXT/NULL record data.
-                                // We'll just assume the rdata is the raw payload, or base32 encoded if it was sent as such.
-                                // Let's just pass the raw data (TXT strings are decoded in DnsPacket::decode)
-                                
-                                // Wait, dnstt server responds with raw bytes in NULL, and base32/chunked strings in TXT.
-                                // Our `DnsPacket::decode` already handles extracting TXT string bytes or NULL raw bytes into `rdata`.
-                                // Let's just send `rdata` to the app.
-                                if transport_tx.send(Bytes::from(answer.rdata)).await.is_err() {
-                                    return; // App closed
-                                }
-                            }
-                        }
-                    }
-                }
-                Err(e) => {
-                    tracing::warn!("DNS transport recv error: {}", e);
-                    break;
-                }
-            }
-        }
-    });
-
-    Ok(Transport::Dns {
-        tx: app_tx,
-        rx: Arc::new(Mutex::new(app_rx)),
-    })
-}

ostp-client/src/transport/mod.rs

@@ -1,4 +1,3 @@
-pub mod dns;
 use std::sync::Arc;
 use tokio::net::UdpSocket;
 use bytes::Bytes;
@@ -10,9 +9,10 @@ pub enum Transport {
         tx: tokio::sync::mpsc::Sender<Bytes>,
         rx: Arc<tokio::sync::Mutex<tokio::sync::mpsc::Receiver<Bytes>>>,
     },
-    Dns {
+    Dnstt {
         tx: tokio::sync::mpsc::Sender<Bytes>,
         rx: Arc<tokio::sync::Mutex<tokio::sync::mpsc::Receiver<Bytes>>>,
+        _guard: Arc<tokio::sync::Mutex<ostp_core::dnstt::DnsttProcess>>,
     }
 }
 
@@ -20,7 +20,7 @@ impl Transport {
     pub async fn send(&self, frame: &Bytes) -> std::io::Result<usize> {
         match self {
             Self::Udp(sock) => sock.send(frame).await,
-            Self::Uot { tx, .. } | Self::Dns { tx, .. } => {
+            Self::Uot { tx, .. } | Self::Dnstt { tx, .. } => {
                 tx.send(frame.clone()).await.map_err(|_| std::io::Error::new(std::io::ErrorKind::BrokenPipe, "channel closed"))?;
                 Ok(frame.len())
             }
@@ -30,31 +30,40 @@ impl Transport {
     pub async fn send_to(&self, frame: &Bytes, target: std::net::SocketAddr) -> std::io::Result<usize> {
         match self {
             Self::Udp(sock) => sock.send_to(frame, target).await,
-            Self::Uot { .. } | Self::Dns { .. } => self.send(frame).await,
+            Self::Uot { .. } | Self::Dnstt { .. } => self.send(frame).await,
         }
     }
 
     pub async fn recv(&self, buf: &mut [u8]) -> std::io::Result<usize> {
         match self {
             Self::Udp(sock) => sock.recv(buf).await,
-            Self::Uot { rx, .. } | Self::Dns { rx, .. } => {
+            Self::Uot { rx, .. } | Self::Dnstt { rx, .. } => {
                 let mut rx = rx.lock().await;
-                match rx.recv().await {
+                if let Some(frame) = rx.recv().await {
-                    Some(bytes) => {
+                    let len = frame.len().min(buf.len());
-                        let len = bytes.len().min(buf.len());
+                    buf[..len].copy_from_slice(&frame[..len]);
-                        buf[..len].copy_from_slice(&bytes[..len]);
+                    Ok(len)
-                        Ok(len)
+                } else {
-                    }
+                    Err(std::io::Error::new(std::io::ErrorKind::UnexpectedEof, "channel closed"))
-                    None => Err(std::io::Error::new(std::io::ErrorKind::BrokenPipe, "channel closed")),
                 }
             }
         }
     }
 
+    pub async fn recv_from(&self, buf: &mut [u8]) -> std::io::Result<(usize, std::net::SocketAddr)> {
+        match self {
+            Self::Udp(sock) => sock.recv_from(buf).await,
+            Self::Uot { .. } | Self::Dnstt { .. } => {
+                let n = self.recv(buf).await?;
+                Ok((n, "127.0.0.1:0".parse().unwrap()))
+            }
+        }
+    }
+
     pub fn local_addr(&self) -> std::io::Result<std::net::SocketAddr> {
         match self {
             Self::Udp(sock) => sock.local_addr(),
-            Self::Uot { .. } | Self::Dns { .. } => Ok("0.0.0.0:0".parse().unwrap()),
+            Self::Uot { .. } | Self::Dnstt { .. } => Ok("0.0.0.0:0".parse().unwrap()),
         }
     }
 }

ostp-client/src/tunnel/balancer.rs

@@ -1,6 +1,5 @@
 use crate::config::{ClientConfig, OutboundConfig};
 use std::collections::HashMap;
-use std::sync::Arc;
 
 pub struct Balancer {
     outbounds: HashMap<String, OutboundConfig>,
@@ -60,6 +59,7 @@ impl Balancer {
     /// Fetches the config for a concrete outbound
     pub fn get_concrete_outbound(&self, tag: &str) -> Option<&OutboundConfig> {
         let resolved_tag = self.resolve_outbound(tag);
+        tracing::debug!("Balancer: tag '{}' resolved to '{}'", tag, resolved_tag);
         self.outbounds.get(&resolved_tag)
     }
 }

ostp-client/src/tunnel/inbounds/local_proxy.rs

@@ -14,13 +14,20 @@ pub async fn run_socks_inbound(
     outbound_manager: Arc<OutboundManager>,
     mut shutdown: watch::Receiver<bool>,
 ) -> Result<()> {
-    let InboundConfig::LocalProxy { tag, protocol, listen, port } = inbound_config else {
+    let InboundConfig::LocalProxy { tag, protocol, listen, port, set_system_proxy } = inbound_config else {
         return Err(anyhow!("Invalid config for LocalProxy inbound"));
     };
 
     let bind_addr = format!("{}:{}", listen, port);
     tracing::info!("Starting {} proxy inbound on {} (tag: {})", protocol, bind_addr, tag);
 
+    let _proxy_guard = if set_system_proxy {
+        let proxy_host = if listen == "0.0.0.0" { "127.0.0.1" } else { &listen };
+        Some(crate::sysproxy::SystemProxyGuard::enable(&format!("{}:{}", proxy_host, port)))
+    } else {
+        None
+    };
+
     let listener = TcpListener::bind(&bind_addr).await?;
 
     loop {
@@ -85,7 +92,7 @@ async fn handle_socks5_connection(
     }
     
     let atyp = buf[3];
-    let (target_host, mut ip_addr) = match atyp {
+    let (target_host, ip_addr) = match atyp {
         0x01 => { // IPv4
             stream.read_exact(&mut buf[0..4]).await?;
             let ip = std::net::Ipv4Addr::new(buf[0], buf[1], buf[2], buf[3]);

ostp-client/src/tunnel/inbounds/tun.rs

@@ -1,6 +1,7 @@
 use anyhow::{anyhow, Result};
 use std::sync::Arc;
 use crate::config::{ClientConfig, InboundConfig};
+#[allow(unused_imports)]
 use crate::tunnel::router::{Router, Session};
 use crate::tunnel::outbounds::OutboundManager;
 use tokio::sync::watch;
@@ -13,7 +14,7 @@ pub async fn run_tun_inbound(
     outbound_manager: Arc<OutboundManager>,
     mut shutdown: watch::Receiver<bool>,
 ) -> Result<()> {
-    use std::net::ToSocketAddrs;
+    
     use netstack_smoltcp::StackBuilder;
     use tokio::io::{AsyncReadExt, AsyncWriteExt};
     use futures::{StreamExt, SinkExt};
@@ -72,7 +73,7 @@ pub async fn run_tun_inbound(
     #[allow(unused_variables)]
     let mut _route_guard = None;
 
-    let (mut tun_to_stack, mut stack_to_tun) = {
+    let (tun_to_stack, stack_to_tun) = {
         #[cfg(target_os = "android")]
         {
             if let Some(fd) = fd {
@@ -183,7 +184,7 @@ pub async fn run_tun_inbound(
     let router_tcp = router.clone();
     let tag_tcp = tag.clone();
     
-    let mut tcp_accept_task = tokio::spawn(async move {
+    let tcp_accept_task = tokio::spawn(async move {
         let Some(mut listener) = tcp_listener else { return; };
         while let Some((mut stream, local, remote)) = listener.next().await {
             let om = outbound_manager_tcp.clone();
@@ -249,7 +250,7 @@ pub async fn run_tun_inbound(
     let router_udp = router.clone();
     let tag_udp = tag.clone();
     
-    let mut udp_proxy_task = tokio::spawn(async move {
+    let udp_proxy_task = tokio::spawn(async move {
         if let Some(udp_sock) = udp_socket {
             let (mut udp_rx, _udp_tx) = udp_sock.split();
             while let Some((payload, local, remote)) = udp_rx.next().await {

ostp-client/src/tunnel/outbounds/direct.rs

@@ -66,7 +66,7 @@ pub fn bind_socket_to_interface(socket: &tokio::net::TcpSocket, _is_ipv6: bool,
     Ok(())
 }
 
-pub async fn dial_tcp(target_host: &str, target_port: u16, phys_if_idx: Option<u32>) -> Result<TcpStream> {
+pub async fn dial_tcp(target_host: &str, target_port: u16, _phys_if_idx: Option<u32>) -> Result<TcpStream> {
     let addrs = tokio::net::lookup_host((target_host, target_port)).await?.collect::<Vec<_>>();
     if addrs.is_empty() {
         return Err(anyhow!("Could not resolve target host: {}", target_host));
@@ -79,7 +79,7 @@ pub async fn dial_tcp(target_host: &str, target_port: u16, phys_if_idx: Option<u
     };
 
     #[cfg(target_os = "windows")]
-    if let Some(idx) = phys_if_idx {
+    if let Some(idx) = _phys_if_idx {
         if let Err(e) = bind_socket_to_interface(&socket, target_addr.is_ipv6(), idx) {
             tracing::warn!("DIRECT: Failed to bind to physical interface {}: {}", idx, e);
         }

ostp-client/src/tunnel/outbounds/mod.rs

@@ -1,6 +1,5 @@
 use anyhow::{anyhow, Result};
 use std::sync::Arc;
-use tokio::net::TcpStream;
 use crate::tunnel::balancer::Balancer;
 use crate::config::OutboundConfig;
 
@@ -12,7 +11,7 @@ pub mod socks;
 pub struct OutboundManager {
     balancer: Arc<Balancer>,
     phys_if_index: Option<u32>,
-    phys_if_name: Option<String>,
+    _phys_if_name: Option<String>,
 }
 
 impl OutboundManager {
@@ -24,7 +23,7 @@ impl OutboundManager {
         Self {
             balancer,
             phys_if_index,
-            phys_if_name,
+            _phys_if_name: phys_if_name,
         }
     }
 
@@ -40,7 +39,7 @@ impl OutboundManager {
                 block::dial_tcp(target_host, target_port).await
             }
             OutboundConfig::Ostp { server, port, access_key, transport, multiplex, .. } => {
-                ostp::dial_tcp(server, *port, access_key, transport, multiplex).await
+                ostp::dial_tcp(target_host, target_port, server, *port, access_key, transport, multiplex).await
             }
             OutboundConfig::Socks { server, port, .. } => {
                 socks::dial_tcp(target_host, target_port, server, *port).await

ostp-client/src/tunnel/outbounds/ostp.rs

@@ -1,76 +1,215 @@
-use anyhow::{anyhow, Result};
+use anyhow::Result;
 use tokio::net::TcpStream;
 use crate::config::{TransportConfig, MultiplexConfig};
 
-use ostp_core::{NoiseRole, OstpEvent, ProtocolAction, ProtocolConfig, ProtocolMachine};
+use ostp_core::{OstpEvent, ProtocolAction, ProtocolConfig, ProtocolMachine};
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
-use tokio::net::UdpSocket;
+
+/// Build the handshake payload the server expects:
+/// [timestamp_u64_be (8 bytes)] [session_id_u32_be (4 bytes)] [access_key bytes]
+fn build_handshake_payload(session_id: u32, access_key: &str) -> Vec<u8> {
+    let ts = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs();
+    let mut payload = Vec::with_capacity(12 + access_key.len());
+    payload.extend_from_slice(&ts.to_be_bytes());
+    payload.extend_from_slice(&session_id.to_be_bytes());
+    payload.extend_from_slice(access_key.as_bytes());
+    payload
+}
+
+/// Build a correctly configured ProtocolConfig for an outgoing OSTP connection.
+fn make_initiator_config(
+    session_id: u32,
+    access_key: &str,
+    transport_cfg: &TransportConfig,
+) -> ProtocolConfig {
+    let secrets = ostp_core::crypto::derive_all_secrets(access_key.as_bytes());
+    let payload = build_handshake_payload(session_id, access_key);
+    
+    let mtu = match transport_cfg.r#type.as_str() {
+        "dns" => 1100,
+        _ => 1350,
+    };
+    // For DNS transport: use larger ack_delay and rto to match DNS round-trip latency
+    // (each DNS query + reply takes 300-800ms end-to-end through Cloudflare).
+    // For UDP: minimize ack_delay to 1ms (ACK asap) and let CC drive the RTO.
+    let (ack_delay_ms, rto_ms) = match transport_cfg.r#type.as_str() {
+        "dns" => (50, 1500),
+        _ => (1, 200),
+    };
+
+    ProtocolConfig {
+        role: ostp_core::NoiseRole::Initiator,
+        psk: secrets.psk,
+        session_id,
+        handshake_payload: payload,
+        max_padding: 256,
+        padding_strategy: ostp_core::framing::PaddingStrategy::Adaptive,
+        obfuscation_key: secrets.obfuscation_key,
+        max_reorder: 16384,
+        max_reorder_buffer: 8192,
+        ack_delay_ms,
+        rto_ms,
+        max_retries: 8,
+        max_sent_history: 32768,
+        handshake_pad_min: secrets.handshake_pad_min,
+        handshake_pad_max: secrets.handshake_pad_max,
+        mtu,
+    }
+}
+
+fn random_session_id() -> u32 {
+    use std::collections::hash_map::DefaultHasher;
+    use std::hash::{Hash, Hasher};
+    let mut h = DefaultHasher::new();
+    std::time::Instant::now().hash(&mut h);
+    std::thread::current().id().hash(&mut h);
+    h.finish() as u32
+}
 
 pub async fn dial_tcp(
+    target_host: &str,
+    target_port: u16,
     server: &str,
     port: u16,
     access_key: &str,
     transport_cfg: &TransportConfig,
     _multiplex: &MultiplexConfig,
 ) -> Result<TcpStream> {
+    tracing::info!("Dialing OSTP server {}:{} for target {}:{}", server, port, target_host, target_port);
     let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await?;
     let local_addr = listener.local_addr()?;
     let client_stream = tokio::net::TcpStream::connect(local_addr).await?;
     let (mut server_stream, _) = listener.accept().await?;
 
-    let transport = match transport_cfg.r#type.as_str() {
+    let transport = make_transport(transport_cfg, server, port).await?;
-        "dns" => {
-            let domain = transport_cfg.domain.clone().unwrap_or_else(|| "tunnel.example.com".to_string());
-            let resolver = transport_cfg.resolver.clone().unwrap_or_else(|| "8.8.8.8".to_string());
-            crate::transport::dns::start_dns_transport(domain, resolver, transport_cfg.pubkey.clone()).await?
-        }
-        // Fallback to UDP for now if unknown
-        _ => {
-            let udp = tokio::net::UdpSocket::bind("0.0.0.0:0").await?;
-            udp.connect((server, port)).await?;
-            crate::transport::Transport::Udp(std::sync::Arc::new(udp))
-        }
-    };
-    
-    let mut psk = [0u8; 32];
-    let key_bytes = access_key.as_bytes();
-    let len = key_bytes.len().min(32);
-    psk[..len].copy_from_slice(&key_bytes[..len]);
-    
-    let config = ProtocolConfig {
-        role: ostp_core::NoiseRole::Initiator,
-        psk,
-        session_id: 1,
-        handshake_payload: vec![],
-        max_padding: 0,
-        padding_strategy: ostp_core::framing::PaddingStrategy::Fixed(0),
-        obfuscation_key: [0; 8],
-        max_reorder: 16384,
-        max_reorder_buffer: 8192,
-        ack_delay_ms: 10,
-        rto_ms: 100,
-        max_retries: 5,
-        max_sent_history: 32768,
-        handshake_pad_min: 8,
-        handshake_pad_max: 24,
-        mtu: 1400,
-    };
 
+    let session_id = random_session_id();
+    let config = make_initiator_config(session_id, access_key, transport_cfg);
     let mut machine = ProtocolMachine::new(config).unwrap();
 
-    // Spawn bridge task
+    let target_host_str = target_host.to_string();
-    tokio::spawn(async move {
+
-        if let Ok(action) = machine.on_event(OstpEvent::Start) {
+        let server_str = server.to_string();
+        
+        // Spawn bridge task
+        tokio::spawn(async move {
+            // Send initial handshake
+            if let Ok(action) = machine.on_event(OstpEvent::Start) {
+                handle_action(action, &transport, &mut server_stream).await;
+            }
+    
+            // Wait for handshake response (server sends HandshakePayload back)
+            let mut buf = [0u8; 8192];
+            let mut handshake_success = false;
+            match tokio::time::timeout(
+                std::time::Duration::from_millis(15000),
+                transport.recv(&mut buf),
+            ).await {
+                Ok(Ok(n)) => {
+                    if let Ok(action) = machine.on_event(OstpEvent::Inbound(bytes::Bytes::copy_from_slice(&buf[..n]))) {
+                        handle_action(action, &transport, &mut server_stream).await;
+                        handshake_success = true;
+                    }
+                }
+                _ => {
+                    tracing::warn!("OSTP handshake timeout for {}:{}", server_str, port);
+                    return;
+                }
+            }
+
+        if !handshake_success {
+            tracing::warn!("TCP handshake failed or protocol machine error");
+            return;
+        }
+
+        // Send connection request
+        let connect_msg = ostp_core::relay::RelayMessage::Connect(format!("{}:{}", target_host_str, target_port));
+        let connect_encoded = connect_msg.encode();
+        if let Ok(action) = machine.on_event(OstpEvent::Outbound(1, bytes::Bytes::from(connect_encoded))) {
             handle_action(action, &transport, &mut server_stream).await;
         }
+
+        // ── Wait for ConnectOk before forwarding any data ─────────────────
+        // This is critical: if we enter the data loop immediately, the TLS
+        // ClientHello arrives at the server before it has established the
+        // outbound TCP connection, causing it to drop the packet as
+        // "Relay DATA for unknown stream".
+        // The kernel will buffer incoming data from server_stream while we wait.
+        let mut connect_ok = false;
+        match tokio::time::timeout(
+            std::time::Duration::from_secs(30),
+            async {
+                let mut wait_buf = [0u8; 8192];
+                loop {
+                    tokio::select! {
+                        Ok(n) = transport.recv(&mut wait_buf) => {
+                            if let Ok(action) = machine.on_event(OstpEvent::Inbound(
+                                bytes::Bytes::copy_from_slice(&wait_buf[..n]),
+                            )) {
+                                // Check for ConnectOk or Error before dispatching
+                                let result = check_connect_result(&action);
+                                handle_action(action, &transport, &mut server_stream).await;
+                                match result {
+                                    Some(true) => return true,
+                                    Some(false) => return false,
+                                    None => {}
+                                }
+                            }
+                        }
+                        _ = tokio::time::sleep(std::time::Duration::from_millis(10)) => {
+                            if let Ok(action) = machine.on_event(OstpEvent::Tick) {
+                                handle_action(action, &transport, &mut server_stream).await;
+                            }
+                        }
+                    }
+                }
+            },
+        )
+        .await
+        {
+            Ok(true) => {
+                tracing::debug!("ConnectOk received for {}:{}, starting data forwarding", target_host_str, target_port);
+                connect_ok = true;
+            }
+            Ok(false) => {
+                tracing::warn!("Server refused connection to {}:{}", target_host_str, target_port);
+            }
+            Err(_) => {
+                tracing::warn!("ConnectOk timeout for {}:{}", target_host_str, target_port);
+            }
+        }
+
+        if !connect_ok {
+            return;
+        }
+
+        // ── Main bidirectional data forwarding loop ───────────────────────
+        // Backpressure: we track how many frames are in-flight vs the congestion
+        // window. When the window is full we stop reading from the TCP stream
+        // (the kernel buffers it) until the remote ACKs enough frames.
+        // This prevents overrunning the sender's sent_history and collapsing cwnd.
         let mut buf = [0u8; 65535];
         let mut udp_buf = [0u8; 65535];
 
         loop {
+            // Compute adaptive tick interval:
+            //   - If there is a pending ACK: tick = ack_delay (flush it quickly)
+            //   - Otherwise: tick = rto/4 (check retransmits without busy-spinning)
+            //   Floor at 1ms, ceiling at 50ms.
+            let tick_ms = (machine.rto().as_millis() / 4).clamp(1, 50) as u64;
+
+            let can_send = machine.in_flight_count() < machine.cwnd_packets().max(4);
+
             tokio::select! {
-                Ok(n) = server_stream.read(&mut buf) => {
+                // Only read from the application TCP stream when cwnd allows
+                Ok(n) = server_stream.read(&mut buf), if can_send => {
                     if n == 0 { break; }
-                    if let Ok(action) = machine.on_event(OstpEvent::Outbound(1, bytes::Bytes::copy_from_slice(&buf[..n]))) {
+                    let data_msg = ostp_core::relay::RelayMessage::Data(buf[..n].to_vec());
+                    let encoded = data_msg.encode();
+                    if let Ok(action) = machine.on_event(OstpEvent::Outbound(1, bytes::Bytes::from(encoded))) {
                         handle_action(action, &transport, &mut server_stream).await;
                     }
                 }
@@ -79,7 +218,7 @@ pub async fn dial_tcp(
                         handle_action(action, &transport, &mut server_stream).await;
                     }
                 }
-                _ = tokio::time::sleep(std::time::Duration::from_millis(10)) => {
+                _ = tokio::time::sleep(std::time::Duration::from_millis(tick_ms)) => {
                     if let Ok(action) = machine.on_event(OstpEvent::Tick) {
                         handle_action(action, &transport, &mut server_stream).await;
                     }
@@ -88,6 +227,7 @@ pub async fn dial_tcp(
         }
     });
 
+
     Ok(client_stream)
 }
 
@@ -101,64 +241,55 @@ pub async fn handle_udp(
     transport_cfg: &TransportConfig,
     _multiplex: &MultiplexConfig,
 ) -> Result<()> {
-    let transport = match transport_cfg.r#type.as_str() {
+    let transport = make_transport(transport_cfg, server, port).await?;
-        "dns" => {
+
-            let domain = transport_cfg.domain.clone().unwrap_or_else(|| "tunnel.example.com".to_string());
+    // Derive session_id from client source addr for stable per-flow sessions
-            let resolver = transport_cfg.resolver.clone().unwrap_or_else(|| "8.8.8.8".to_string());
+    let ip_bytes = match client_src.ip() {
-            crate::transport::dns::start_dns_transport(domain, resolver, transport_cfg.pubkey.clone()).await?
+        std::net::IpAddr::V4(v4) => {
+            let o = v4.octets();
+            u32::from_be_bytes(o)
         }
-        _ => {
+        std::net::IpAddr::V6(v6) => {
-            let udp = tokio::net::UdpSocket::bind("0.0.0.0:0").await?;
+            let o = v6.octets();
-            udp.connect((server, port)).await?;
+            u32::from_be_bytes([o[12], o[13], o[14], o[15]])
-            crate::transport::Transport::Udp(std::sync::Arc::new(udp))
         }
     };
+    let session_id = ip_bytes ^ (client_src.port() as u32);
 
-    let mut psk = [0u8; 32];
+    let config = make_initiator_config(session_id, access_key, transport_cfg);
-    let key_bytes = access_key.as_bytes();
-    let len = key_bytes.len().min(32);
-    psk[..len].copy_from_slice(&key_bytes[..len]);
-
-    let config = ProtocolConfig {
-        role: ostp_core::NoiseRole::Initiator,
-        psk,
-        session_id: u32::from_ne_bytes([
-            client_src.ip().to_string().as_bytes().get(0).copied().unwrap_or(0),
-            client_src.ip().to_string().as_bytes().get(1).copied().unwrap_or(0),
-            client_src.ip().to_string().as_bytes().get(2).copied().unwrap_or(0),
-            client_src.ip().to_string().as_bytes().get(3).copied().unwrap_or(0),
-        ]),
-        handshake_payload: vec![],
-        max_padding: 0,
-        padding_strategy: ostp_core::framing::PaddingStrategy::Fixed(0),
-        obfuscation_key: [0; 8],
-        max_reorder: 4096,
-        max_reorder_buffer: 2048,
-        ack_delay_ms: 50,
-        rto_ms: 200,
-        max_retries: 3,
-        max_sent_history: 8192,
-        handshake_pad_min: 8,
-        handshake_pad_max: 24,
-        mtu: 1400,
-    };
-
     let mut machine = ProtocolMachine::new(config)?;
 
-    // Send initial packet with UDP payload
+    // Send handshake first
     if let Ok(action) = machine.on_event(OstpEvent::Start) {
         handle_udp_action(action, &transport).await;
     }
 
-    // Send the actual UDP payload
+    // Wait for handshake response (server sends HandshakePayload back)
-    let relay_msg = ostp_core::relay::RelayMessage::Connect(format!("{}:{}", target_dst.ip(), target_dst.port()));
+    let mut buf = [0u8; 8192];
-    let encoded = relay_msg.encode();
+    match tokio::time::timeout(
+        std::time::Duration::from_millis(15000),
+        transport.recv(&mut buf),
+    ).await {
+        Ok(Ok(n)) => {
+            let _ = machine.on_event(OstpEvent::Inbound(bytes::Bytes::copy_from_slice(&buf[..n])));
+        }
+        _ => {
+            tracing::warn!("OSTP handshake timeout for {}:{}", server, port);
+            return Ok(());
+        }
+    }
+
+    // Send relay UdpAssociate + data
+    let assoc_msg = ostp_core::relay::RelayMessage::UdpAssociate;
+    let encoded = assoc_msg.encode();
     if let Ok(action) = machine.on_event(OstpEvent::Outbound(1, bytes::Bytes::from(encoded))) {
         handle_udp_action(action, &transport).await;
     }
 
-    // Send data packet
+    let data_msg = ostp_core::relay::RelayMessage::UdpData(
-    let data_msg = ostp_core::relay::RelayMessage::Data(payload.to_vec());
+        format!("{}:{}", target_dst.ip(), target_dst.port()),
+        payload.to_vec()
+    );
     let encoded = data_msg.encode();
     if let Ok(action) = machine.on_event(OstpEvent::Outbound(1, bytes::Bytes::from(encoded))) {
         handle_udp_action(action, &transport).await;
@@ -166,13 +297,15 @@ pub async fn handle_udp(
 
     // Keep-alive for a short time to receive response
     for _ in 0..5 {
-        let mut buf = [0u8; 8192];
         match tokio::time::timeout(
             std::time::Duration::from_millis(100),
-            transport.recv(&mut buf)
+            transport.recv(&mut buf),
         ).await {
             Ok(Ok(n)) => {
-                let _ = machine.on_event(OstpEvent::Inbound(bytes::Bytes::copy_from_slice(&buf[..n])));
+                if let Ok(action) = machine.on_event(OstpEvent::Inbound(bytes::Bytes::copy_from_slice(&buf[..n]))) {
+                    // Just process incoming UDP response internally
+                    let _ = action;
+                }
             }
             _ => break,
         }
@@ -181,6 +314,76 @@ pub async fn handle_udp(
     Ok(())
 }
 
+async fn make_transport(
+    transport_cfg: &TransportConfig,
+    server: &str,
+    port: u16,
+) -> Result<crate::transport::Transport> {
+    let debug = tracing::enabled!(tracing::Level::DEBUG);
+    match transport_cfg.r#type.as_str() {
+        "dns" => {
+            let domain = transport_cfg.domain.clone()
+                .unwrap_or_else(|| "tunnel.example.com".to_string());
+            let pubkey = transport_cfg.pubkey.clone()
+                .unwrap_or_else(|| "".to_string());
+            let resolver = transport_cfg.resolver.clone()
+                .unwrap_or_else(|| server.to_string());
+            let resolver_with_port = if resolver.contains(':') {
+                resolver.clone()
+            } else {
+                format!("{}:53", resolver)
+            };
+                
+            let (local_port, process) = ostp_core::dnstt::spawn_client(&pubkey, &domain, &resolver_with_port, debug)?;
+            
+            // Wait for dnstt-client to start its local TCP listener
+            tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
+            
+            // Connect TCP to the local dnstt-client port
+            let stream = tokio::net::TcpStream::connect(("127.0.0.1", local_port)).await?;
+            let (mut rh, mut wh) = stream.into_split();
+            
+            let (tx_send, mut tx_recv) = tokio::sync::mpsc::channel::<bytes::Bytes>(1024);
+            let (rx_send, rx_recv) = tokio::sync::mpsc::channel::<bytes::Bytes>(1024);
+            
+            // Writer task
+            tokio::spawn(async move {
+                use tokio::io::AsyncWriteExt;
+                while let Some(data) = tx_recv.recv().await {
+                    let len = data.len() as u16;
+                    if wh.write_u16(len).await.is_err() { break; }
+                    if wh.write_all(&data).await.is_err() { break; }
+                }
+            });
+            
+            // Reader task
+            tokio::spawn(async move {
+                use tokio::io::AsyncReadExt;
+                loop {
+                    let len = match rh.read_u16().await {
+                        Ok(l) => l,
+                        Err(_) => break,
+                    };
+                    let mut buf = vec![0u8; len as usize];
+                    if rh.read_exact(&mut buf).await.is_err() { break; }
+                    if rx_send.send(bytes::Bytes::from(buf)).await.is_err() { break; }
+                }
+            });
+            
+            Ok(crate::transport::Transport::Dnstt {
+                tx: tx_send,
+                rx: std::sync::Arc::new(tokio::sync::Mutex::new(rx_recv)),
+                _guard: std::sync::Arc::new(tokio::sync::Mutex::new(process)),
+            })
+        }
+        _ => {
+            let udp = tokio::net::UdpSocket::bind("0.0.0.0:0").await?;
+            udp.connect((server, port)).await?;
+            Ok(crate::transport::Transport::Udp(std::sync::Arc::new(udp)))
+        }
+    }
+}
+
 async fn handle_udp_action(action: ProtocolAction, transport: &crate::transport::Transport) {
     match action {
         ProtocolAction::SendDatagram(data) => {
@@ -203,17 +406,53 @@ async fn handle_action(action: ProtocolAction, transport: &crate::transport::Tra
             let _ = transport.send(&data).await;
         }
         ProtocolAction::DeliverApp(_stream_id, payload) => {
-            let _ = server_stream.write_all(&payload).await;
+            if let Ok(msg) = ostp_core::relay::RelayMessage::decode(&payload) {
+                match msg {
+                    ostp_core::relay::RelayMessage::Data(data) => {
+                        let _ = server_stream.write_all(&data).await;
+                    }
+                    ostp_core::relay::RelayMessage::ConnectOk => {
+                        tracing::debug!("TCP Connection established successfully");
+                    }
+                    ostp_core::relay::RelayMessage::Error(err) => {
+                        tracing::warn!("Server returned TCP connection error: {}", err);
+                    }
+                    _ => {}
+                }
+            }
         }
         ProtocolAction::Multiple(actions) => {
             for a in actions {
-                match a {
+                Box::pin(handle_action(a, transport, server_stream)).await;
-                    ProtocolAction::SendDatagram(data) => { let _ = transport.send(&data).await; }
-                    ProtocolAction::DeliverApp(_stream_id, payload) => { let _ = server_stream.write_all(&payload).await; }
-                    _ => {}
-                }
             }
         }
         _ => {}
     }
 }
+
+/// Inspect a ProtocolAction for ConnectOk / Error relay messages.
+/// Returns Some(true) on ConnectOk, Some(false) on Error, None if neither.
+/// Works recursively through Multiple actions.
+fn check_connect_result(action: &ProtocolAction) -> Option<bool> {
+    match action {
+        ProtocolAction::DeliverApp(_stream_id, payload) => {
+            if let Ok(msg) = ostp_core::relay::RelayMessage::decode(payload) {
+                match msg {
+                    ostp_core::relay::RelayMessage::ConnectOk => return Some(true),
+                    ostp_core::relay::RelayMessage::Error(_) => return Some(false),
+                    _ => {}
+                }
+            }
+            None
+        }
+        ProtocolAction::Multiple(actions) => {
+            for a in actions {
+                if let Some(result) = check_connect_result(a) {
+                    return Some(result);
+                }
+            }
+            None
+        }
+        _ => None,
+    }
+}

ostp-client/src/tunnel/process_lookup.rs

@@ -126,7 +126,6 @@ pub fn get_process_name_from_port(port: u16) -> Option<String> {
     use std::fs;
     use std::io::{BufRead, BufReader};
 
-    let mut target_inode = None;
     let hex_port = format!("{:04X}", port);
 
     let check_net_file = |path: &str| -> Option<u64> {
@@ -146,12 +145,11 @@ pub fn get_process_name_from_port(port: u16) -> Option<String> {
         None
     };
 
-    target_inode = check_net_file("/proc/net/tcp")
+    let target_inode = check_net_file("/proc/net/tcp")
         .or_else(|| check_net_file("/proc/net/tcp6"))
         .or_else(|| check_net_file("/proc/net/udp"))
-        .or_else(|| check_net_file("/proc/net/udp6"));
+        .or_else(|| check_net_file("/proc/net/udp6"))?;
 
-    let target_inode = target_inode?;
     let socket_str = format!("socket:[{}]", target_inode);
 
     for entry in fs::read_dir("/proc").ok()?.filter_map(Result::ok) {

ostp-core/Cargo.toml

@@ -17,3 +17,5 @@ sha2.workspace = true
 hmac.workspace = true
 x25519-dalek = { version = "2.0.1", features = ["static_secrets"] }
 hkdf = "0.12.0"
+tokio.workspace = true
+serde = { version = "1.0", features = ["derive"] }

ostp-core/src/congestion.rs

@@ -4,6 +4,12 @@
 //! bandwidth and minimum RTT to determine the optimal sending rate.
 //! This replaces the fixed `retransmit_budget = 8` with an adaptive
 //! congestion window that responds to network conditions.
+//!
+//! RTO calculation follows RFC 6298:
+//!   SRTT = (1 - α) * SRTT + α * RTT       (α = 1/8)
+//!   RTTVAR = (1 - β) * RTTVAR + β * |SRTT - RTT|  (β = 1/4)
+//!   RTO = SRTT + 4 * RTTVAR
+//!   clamped to [RTO_MIN, RTO_MAX]
 
 use std::time::{Duration, Instant};
 
@@ -15,8 +21,14 @@ pub struct CongestionController {
     ssthresh: u64,
     /// Current phase
     phase: Phase,
-    /// Minimum RTT observed
+    /// Minimum RTT observed (for BBR-style bandwidth estimation)
     min_rtt: Duration,
+    /// Smoothed RTT (RFC 6298 SRTT)
+    srtt: Duration,
+    /// RTT variance (RFC 6298 RTTVAR)
+    rttvar: Duration,
+    /// Whether we have received a first RTT sample
+    rtt_initialized: bool,
     /// Bytes currently in flight (unacknowledged)
     bytes_in_flight: u64,
     /// Total bytes acknowledged (for bandwidth estimation)
@@ -37,31 +49,43 @@ pub struct CongestionController {
 enum Phase {
     /// Exponential growth until loss or ssthresh
     SlowStart,
-    /// Probe bandwidth: cycle through pacing gains
+    /// Probe bandwidth: additive increase
     ProbeBandwidth,
 }
 
-/// Initial congestion window: 10 packets × MTU
+/// Initial congestion window: 32 packets × MTU (IW10 is too conservative for modern links)
-const INITIAL_CWND_PACKETS: u64 = 10;
+const INITIAL_CWND_PACKETS: u64 = 32;
 /// Minimum cwnd: 2 packets
 const MIN_CWND_PACKETS: u64 = 2;
 /// Min RTT expiry window (after which we re-probe)
 const MIN_RTT_EXPIRY: Duration = Duration::from_secs(10);
+/// Minimum RTO (RFC 6298: 1s in TCP; we use 50ms since we own the protocol)
+const RTO_MIN: Duration = Duration::from_millis(50);
+/// Maximum RTO
+const RTO_MAX: Duration = Duration::from_secs(16);
+/// Initial RTT estimate — 30 ms is reasonable for a well-connected VPN server.
+/// Will be replaced by first real measurement within milliseconds.
+const INITIAL_RTT: Duration = Duration::from_millis(30);
 
 impl CongestionController {
     pub fn new(mtu: u64) -> Self {
         let now = Instant::now();
         let initial_cwnd = INITIAL_CWND_PACKETS * mtu;
+        // Initial pacing: deliver cwnd in ~2 RTTs to fill the pipe quickly
+        let initial_pacing = initial_cwnd * 1_000_000 / INITIAL_RTT.as_micros().max(1) as u64;
         Self {
             cwnd: initial_cwnd,
             ssthresh: u64::MAX,
             phase: Phase::SlowStart,
-            min_rtt: Duration::from_millis(100), // Conservative initial estimate
+            min_rtt: INITIAL_RTT,
+            srtt: INITIAL_RTT,
+            rttvar: INITIAL_RTT / 2,
+            rtt_initialized: false,
             bytes_in_flight: 0,
             total_acked: 0,
             last_ack_time: now,
             loss_count: 0,
-            pacing_rate: initial_cwnd * 10, // initial: ~10 windows/sec
+            pacing_rate: initial_pacing,
             mtu,
             min_rtt_stamp: now,
         }
@@ -82,9 +106,20 @@ impl CongestionController {
         self.pacing_rate
     }
 
-    /// Returns the smoothed RTT estimate.
+    /// Returns the smoothed RTT estimate (SRTT).
     pub fn smoothed_rtt(&self) -> Duration {
-        self.min_rtt
+        self.srtt
+    }
+
+    /// Returns the adaptive RTO computed per RFC 6298:
+    ///   RTO = SRTT + 4 * RTTVAR, clamped to [RTO_MIN, RTO_MAX].
+    ///
+    /// This replaces the static `rto_ms` field in ProtocolMachine so that
+    /// retransmit timers automatically track changing network conditions.
+    pub fn rto(&self) -> Duration {
+        let rttvar4 = self.rttvar.saturating_mul(4);
+        let rto = self.srtt.saturating_add(rttvar4);
+        rto.clamp(RTO_MIN, RTO_MAX)
     }
 
     /// Returns how many bytes can still be sent.
@@ -115,16 +150,13 @@ impl CongestionController {
         self.bytes_in_flight = self.bytes_in_flight.saturating_sub(bytes);
         self.total_acked = self.total_acked.saturating_add(bytes);
 
-        // Update RTT
+        // Update RTT measurements
         self.update_rtt(rtt, now);
 
-        // Update bandwidth estimate
-        self.update_bandwidth(bytes, now);
-
         // State machine
         match self.phase {
             Phase::SlowStart => {
-                // Exponential growth: increase cwnd by acked bytes
+                // Exponential growth: increase cwnd by acked bytes (doubles per RTT)
                 self.cwnd = self.cwnd.saturating_add(bytes);
                 if self.cwnd >= self.ssthresh {
                     self.phase = Phase::ProbeBandwidth;
@@ -164,32 +196,49 @@ impl CongestionController {
         self.update_pacing_rate();
     }
 
-    /// Called periodically to update state.
-    pub fn on_tick(&mut self) {
-        // Nothing special needed per-tick -- state updates happen on ACK/loss
-    }
-
     // ── Private ──────────────────────────────────────────────────────────────
 
     fn update_rtt(&mut self, rtt: Duration, now: Instant) {
-        // Track windowed minimum RTT
+        // Update windowed minimum RTT (for pacing)
         if rtt < self.min_rtt || now.duration_since(self.min_rtt_stamp) >= MIN_RTT_EXPIRY {
             self.min_rtt = rtt;
             self.min_rtt_stamp = now;
         }
-    }
 
-    fn update_bandwidth(&mut self, _acked_bytes: u64, now: Instant) {
+        // Update SRTT and RTTVAR per RFC 6298
-        let elapsed = now.duration_since(self.last_ack_time);
+        if !self.rtt_initialized {
-        if elapsed.as_micros() > 0 {
+            // First measurement: initialize directly
-        // Removed bw_samples tracking
+            self.srtt = rtt;
+            self.rttvar = rtt / 2;
+            self.rtt_initialized = true;
+        } else {
+            // RTTVAR = (3/4) * RTTVAR + (1/4) * |SRTT - R|
+            let diff = if rtt > self.srtt {
+                rtt - self.srtt
+            } else {
+                self.srtt - rtt
+            };
+            // Integer-safe: RTTVAR = RTTVAR - RTTVAR/4 + diff/4
+            self.rttvar = self.rttvar
+                .saturating_sub(self.rttvar / 4)
+                .saturating_add(diff / 4);
+
+            // SRTT = (7/8) * SRTT + (1/8) * R
+            self.srtt = self.srtt
+                .saturating_sub(self.srtt / 8)
+                .saturating_add(rtt / 8);
         }
+
+        tracing::trace!(
+            srtt_ms = self.srtt.as_millis(),
+            rttvar_ms = self.rttvar.as_millis(),
+            rto_ms = self.rto().as_millis(),
+            "congestion: RTT updated"
+        );
     }
 
-
-
     fn update_pacing_rate(&mut self) {
-        // Pacing rate = cwnd / min_rtt (with gain)
+        // Pacing rate = cwnd / min_rtt (delivery rate target)
         let rtt_us = self.min_rtt.as_micros().max(1) as u64;
         self.pacing_rate = self.cwnd * 1_000_000 / rtt_us;
     }
@@ -202,19 +251,18 @@ mod tests {
     #[test]
     fn test_initial_state() {
         let cc = CongestionController::new(1200);
-        assert_eq!(cc.cwnd(), 12000); // 10 * 1200
+        assert_eq!(cc.cwnd(), 32 * 1200); // 32 * 1200
         assert!(cc.can_send());
-        assert_eq!(cc.cwnd_packets(), 10);
+        assert_eq!(cc.cwnd_packets(), 32);
     }
 
     #[test]
     fn test_slow_start_growth() {
         let mut cc = CongestionController::new(1200);
-        // Simulate sending and ACKing
+        let initial = cc.cwnd();
         cc.on_send(1200);
         cc.on_ack(1200, Duration::from_millis(50));
-        // cwnd should grow
+        assert!(cc.cwnd() > initial);
-        assert!(cc.cwnd() > 12000);
     }
 
     #[test]
@@ -229,7 +277,7 @@ mod tests {
     fn test_can_send_limits() {
         let mut cc = CongestionController::new(1200);
         // Send until cwnd is exhausted
-        for _ in 0..10 {
+        for _ in 0..32 {
             cc.on_send(1200);
         }
         assert!(!cc.can_send()); // cwnd exhausted
@@ -244,10 +292,46 @@ mod tests {
     }
 
     #[test]
-    fn test_rtt_tracking() {
+    fn test_rtt_tracking_first_sample() {
         let mut cc = CongestionController::new(1200);
         cc.on_send(1200);
         cc.on_ack(1200, Duration::from_millis(25));
+        // After first sample: SRTT = 25ms, RTTVAR = 12ms
         assert_eq!(cc.smoothed_rtt(), Duration::from_millis(25));
     }
+
+    #[test]
+    fn test_rto_rfc6298() {
+        let mut cc = CongestionController::new(1200);
+        // After first sample with RTT=50ms: SRTT=50ms, RTTVAR=25ms, RTO=150ms
+        cc.on_send(1200);
+        cc.on_ack(1200, Duration::from_millis(50));
+        let rto = cc.rto();
+        // RTO = 50 + 4*25 = 150ms; clamped to [50ms, 16s]
+        assert!(rto >= RTO_MIN);
+        assert!(rto <= RTO_MAX);
+        assert_eq!(rto, Duration::from_millis(150));
+    }
+
+    #[test]
+    fn test_rto_clamp_min() {
+        let cc = CongestionController::new(1200);
+        // Even with no RTT samples, RTO should not go below RTO_MIN
+        assert!(cc.rto() >= RTO_MIN);
+    }
+
+    #[test]
+    fn test_rto_adapts_after_multiple_samples() {
+        let mut cc = CongestionController::new(1200);
+        // Feed several consistent RTT samples
+        for _ in 0..8 {
+            cc.on_send(1200);
+            cc.on_ack(1200, Duration::from_millis(20));
+        }
+        // After convergence, RTTVAR should be small → RTO close to SRTT + small margin
+        let rto = cc.rto();
+        // Should be well below 100ms (the old hardcoded default)
+        assert!(rto < Duration::from_millis(200));
+        assert!(rto >= RTO_MIN);
+    }
 }

ostp-core/src/dns.rs

@@ -1,5 +1,5 @@
 use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
-use std::io::{Cursor, Read, Write};
+use std::io::{Cursor, Read};
 
 const BASE32_ALPHABET: &[u8] = b"abcdefghijklmnopqrstuvwxyz234567";
 
@@ -136,13 +136,17 @@ impl DnsPacket {
                 qtype: rtype.clone(),
                 qclass: 1, // IN
             }],
-            answers: vec![DnsAnswer {
+            answers: if rdata.is_empty() {
-                name: name.to_string(),
+                vec![]
-                rtype,
+            } else {
-                rclass: 1,
+                vec![DnsAnswer {
-                ttl: 0, // No caching
+                    name: name.to_string(),
-                rdata,
+                    rtype,
-            }],
+                    rclass: 1,
+                    ttl: 0, // No caching
+                    rdata,
+                }]
+            },
         }
     }
 

ostp-core/src/dns_prober.rs

@@ -0,0 +1,94 @@
+use std::time::Duration;
+use tokio::time::Instant;
+use crate::dns::{DnsPacket, DnsRecordType, encode_payload_to_domain};
+use rand::Rng;
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize, Clone)]
+pub struct DnsProbeResult {
+    pub name: String,
+    pub ip: String,
+    pub latency_ms: Option<u64>,
+}
+
+const PUBLIC_DNS_SERVERS: &[(&str, &str)] = &[
+    ("Cloudflare",  "1.1.1.1"),
+    ("Cloudflare2", "1.0.0.1"),
+    ("Google",      "8.8.8.8"),
+    ("Google2",     "8.8.4.4"),
+    ("Quad9",       "9.9.9.9"),
+    ("AdGuard",     "94.140.14.14"),
+    ("Yandex",      "77.88.8.8"),
+    ("Yandex2",     "77.88.8.1"),
+    ("SkyDNS",      "193.58.251.251"),
+    ("AliDNS",      "223.5.5.5"),
+    ("Tencent",     "119.29.29.29"),
+    ("114DNS",      "114.114.114.114"),
+    ("Shecan",      "178.22.122.100"),
+    ("Electro",     "78.157.42.100"),
+    ("Begzar",      "185.55.226.26"),
+];
+
+async fn probe_resolver(domain: &str, resolver_ip: &str) -> Option<u64> {
+    let (probe_bytes, id) = {
+        let mut rng = rand::thread_rng();
+        let probe_bytes: [u8; 4] = rng.gen();
+        let id: u16 = rng.gen();
+        (probe_bytes, id)
+    };
+
+    let fqdn = encode_payload_to_domain(&probe_bytes, domain);
+    let qtype = if rand::thread_rng().gen_bool(0.5) { DnsRecordType::TXT } else { DnsRecordType::NULL };
+    let packet = DnsPacket::new_query(id, &fqdn, qtype);
+    let encoded = packet.encode();
+
+    let sock = tokio::net::UdpSocket::bind("0.0.0.0:0").await.ok()?;
+    sock.connect(format!("{}:53", resolver_ip)).await.ok()?;
+
+    let start = Instant::now();
+    sock.send(&encoded).await.ok()?;
+
+    let mut buf = [0u8; 4096];
+    match tokio::time::timeout(Duration::from_secs(2), sock.recv(&mut buf)).await {
+        Ok(Ok(n)) => {
+            if let Some(resp) = DnsPacket::decode(&buf[..n]) {
+                // Check if RCODE == 0 (NOERROR) and it has answers
+                let rcode = resp.flags & 0x000F;
+                if rcode == 0 && !resp.answers.is_empty() {
+                    return Some(start.elapsed().as_millis() as u64);
+                }
+            }
+            None
+        },
+        _ => None,
+    }
+}
+
+pub async fn run_dns_prober(domain: &str) -> Result<Vec<DnsProbeResult>, String> {
+    if domain.is_empty() {
+        return Err("Please enter the tunnel domain first (e.g. tunnel.myvpn.com)".into());
+    }
+
+    let tasks: Vec<_> = PUBLIC_DNS_SERVERS
+        .iter()
+        .map(|(name, ip)| {
+            let domain = domain.to_string();
+            let name = name.to_string();
+            let ip   = ip.to_string();
+            tokio::spawn(async move {
+                let latency_ms = probe_resolver(&domain, &ip).await;
+                DnsProbeResult { name, ip, latency_ms }
+            })
+        })
+        .collect();
+
+    let mut results = Vec::with_capacity(tasks.len());
+    for task in tasks {
+        if let Ok(r) = task.await {
+            results.push(r);
+        }
+    }
+
+    results.sort_by_key(|r| r.latency_ms.unwrap_or(u64::MAX));
+    Ok(results)
+}

ostp-core/src/lib.rs

@@ -5,6 +5,8 @@ pub mod protocol;
 pub mod relay;
 pub mod resumption;
 pub mod dns;
+pub mod dns_prober;
+pub mod dnstt;
 
 pub use crypto::NoiseRole;
 pub use framing::{TrafficProfile, PaddingStrategy};

ostp-core/src/protocol.rs

@@ -2,7 +2,7 @@ use bytes::Bytes;
 use rand::Rng;
 use sha2::{Digest, Sha256};
 use thiserror::Error;
-use std::collections::{BTreeMap, VecDeque};
+use std::collections::BTreeMap;
 use std::time::{Duration, Instant};
 
 use crate::congestion::CongestionController;
@@ -75,7 +75,7 @@ pub struct ProtocolMachine {
     send_nonce: u64,
     expected_recv_nonce: u64,
     reorder_buffer: BTreeMap<u64, ProtocolAction>,
-    sent_history: VecDeque<SentFrame>,
+    sent_history: BTreeMap<u64, SentFrame>,
     session_id: u32,
     handshake_payload: Vec<u8>,
     padder: AdaptivePadder,
@@ -83,7 +83,8 @@ pub struct ProtocolMachine {
     max_reorder: u64,
     max_reorder_buffer: usize,
     ack_delay: Duration,
-    rto: Duration,
+    /// Initial/fallback RTO from config (overridden by cc.rto() after first RTT sample)
+    rto_initial: Duration,
     max_retries: u8,
     max_sent_history: usize,
     ack_pending: bool,
@@ -100,11 +101,11 @@ pub struct ProtocolMachine {
         /// Key-derived handshake padding range
     handshake_pad_min: usize,
     handshake_pad_max: usize,
-    _mtu: usize,
 }
 
 #[derive(Debug, Clone)]
 struct SentFrame {
+    #[allow(dead_code)] // mirrored in BTreeMap key; kept for Debug output
     nonce: u64,
     bytes: Bytes,
     last_sent: Instant,
@@ -128,7 +129,7 @@ impl ProtocolMachine {
             send_nonce: 0,
             expected_recv_nonce: 0,
             reorder_buffer: BTreeMap::new(),
-            sent_history: VecDeque::with_capacity(config.max_sent_history.max(1)),
+            sent_history: BTreeMap::new(),
             session_id: config.session_id,
             handshake_payload: config.handshake_payload,
             padder: AdaptivePadder::new(config.mtu, config.max_padding, config.padding_strategy),
@@ -136,7 +137,7 @@ impl ProtocolMachine {
             max_reorder: config.max_reorder.max(1),
             max_reorder_buffer: config.max_reorder_buffer.max(1),
             ack_delay: Duration::from_millis(config.ack_delay_ms.max(1)),
-            rto: Duration::from_millis(config.rto_ms.max(1)),
+            rto_initial: Duration::from_millis(config.rto_ms.max(1)),
             max_retries: config.max_retries.max(1),
             max_sent_history: config.max_sent_history.max(1),
             ack_pending: false,
@@ -146,20 +147,25 @@ impl ProtocolMachine {
             cc: CongestionController::new(config.mtu as u64),
             handshake_pad_min: config.handshake_pad_min.max(8),
             handshake_pad_max: config.handshake_pad_max.max(config.handshake_pad_min + 16),
-            _mtu: config.mtu,
         })
     }
 
     pub fn in_flight_count(&self) -> usize {
         // COUNT ONLY retransmittable Data frames — control frames (Ack/Nack) must not
         // contribute to this counter or they will trigger false backpressure.
-        self.sent_history.iter().filter(|f| f.is_retransmittable).count()
+        self.sent_history.values().filter(|f| f.is_retransmittable).count()
     }
 
     pub fn cwnd_packets(&self) -> usize {
         self.cc.cwnd_packets() as usize
     }
 
+    /// Returns the current adaptive RTO (from congestion controller after first RTT sample,
+    /// falls back to the config-specified initial value before any ACK is received).
+    pub fn rto(&self) -> Duration {
+        self.cc.rto()
+    }
+
     pub fn on_send(&mut self, bytes: u64) {
         self.cc.on_send(bytes);
     }
@@ -207,13 +213,12 @@ impl ProtocolMachine {
                     .map(ProtocolAction::SendDatagram)
             }
             (OstpState::Closing, OstpEvent::Inbound(raw)) => {
-                // Process final in-flight packets to prevent data loss during teardown.
+                // The remote may still have data or ACKs in transit.
-                // The remote may still have data or ACKs in transit when we initiated Close.
+                // handle_inbound transitions to Closed when it receives a Close frame.
-                let result = self.handle_inbound(raw);
+                self.handle_inbound(raw)
-                self.state = OstpState::Closed;
-                result
             }
             (OstpState::Established, OstpEvent::Tick) => self.handle_tick(),
+            (OstpState::Closing, OstpEvent::Tick) => self.handle_tick(),
             (OstpState::Closed, _) => Ok(ProtocolAction::Noop),
             (_, OstpEvent::Close) => {
                 self.state = OstpState::Closed;
@@ -392,18 +397,26 @@ impl ProtocolMachine {
             self.last_recv_advance = Instant::now();
         } else {
             // Gap detected
-            if self.reorder_buffer.len() < self.max_reorder_buffer {
+            if self.reorder_buffer.len() >= self.max_reorder_buffer {
-                self.reorder_buffer.insert(nonce, action);
+                tracing::warn!("Reorder buffer full ({}/{}), dropping new frame nonce={} to wait for recovery of nonce={}",
-            } else {
+                    self.reorder_buffer.len(), self.max_reorder_buffer, nonce, self.expected_recv_nonce
-                tracing::warn!("Reorder buffer full ({}/{}), dropping frame nonce={}",
-                    self.reorder_buffer.len(), self.max_reorder_buffer, nonce
                 );
             }
 
-            // Rate-limited NACK: send at most once per 30ms to prevent retransmit storms.
+            if nonce >= self.expected_recv_nonce {
-            // Under high load with natural UDP reordering, sending a NACK per packet
+                if self.reorder_buffer.len() < self.max_reorder_buffer {
-            // causes exponential retransmit explosion that saturates the channel.
+                    self.reorder_buffer.insert(nonce, action);
-            let nack_cooldown = Duration::from_millis(30);
+                } else {
+                    tracing::warn!("Reorder buffer still full after gap recovery, dropping frame nonce={}", nonce);
+                }
+            } else {
+                tracing::debug!("Frame nonce={} arrived too late after gap recovery, dropping", nonce);
+            }
+
+            // Rate-limited NACK: send at most once per (rto/2) to prevent retransmit storms.
+            // Using rto/2 means we send a NACK before the sender's timer fires, prompting
+            // fast retransmit without flooding. Floor at 10ms to handle very low-RTT links.
+            let nack_cooldown = (self.cc.rto() / 2).max(Duration::from_millis(10));
             if self.last_nack_sent.elapsed() >= nack_cooldown {
                 self.last_nack_sent = Instant::now();
                 let nack_payload = self.expected_recv_nonce.to_be_bytes();
@@ -511,62 +524,39 @@ impl ProtocolMachine {
     fn handle_tick(&mut self) -> Result<ProtocolAction, ProtocolError> {
         let mut actions = Vec::new();
 
-        // ── Gap Recovery ──────────────────────────────────────────────
-        // If expected_recv_nonce hasn't advanced for 500ms+ and there
-        // are buffered frames waiting, the sender likely evicted the lost
-        // frame from sent_history. Skip the gap to restore data flow.
-        // This trades a small amount of data loss for connection liveness.
-        if !self.reorder_buffer.is_empty()
-            && self.last_recv_advance.elapsed() > Duration::from_millis(500)
-        {
-            if let Some(&first_buffered) = self.reorder_buffer.keys().next() {
-                let skipped = first_buffered.saturating_sub(self.expected_recv_nonce);
-                self.expected_recv_nonce = first_buffered;
-                self.last_recv_advance = Instant::now();
-
-                let mut delivered = 0u64;
-                while let Some(buffered_action) = self.reorder_buffer.remove(&self.expected_recv_nonce) {
-                    actions.push(buffered_action);
-                    self.expected_recv_nonce = self.expected_recv_nonce.saturating_add(1);
-                    delivered += 1;
-                }
-                self.ack_pending = true;
-                tracing::debug!("Gap recovery: skipped {} lost frames, delivered {} buffered frames (reorder_buf={})",
-                    skipped, delivered, self.reorder_buffer.len()
-                );
-            }
-        }
-
         // ── Pending ACK flush ─────────────────────────────────────────
         if let Some(ack_frame) = self.build_ack_if_due()? {
             actions.push(ProtocolAction::SendDatagram(ack_frame));
         }
 
         let now = Instant::now();
-        let base_rto_ms = self.rto.as_millis().max(1) as u64;
+        // Use the adaptive RTO from the congestion controller (RFC 6298 SRTT + 4*RTTVAR).
+        // Falls back to rto_initial before the first ACK is received.
+        let base_rto = self.cc.rto().max(self.rto_initial);
+        let base_rto_ms = base_rto.as_millis().max(1) as u64;
 
         // ── Zombie frame eviction ────────────────────────────────────
         // Evict frames that exceeded max_retries + 2 grace retries.
-        // Shorter grace period than before (was +4) to free memory faster
-        // after high-throughput bursts.
         let grace = self.max_retries.saturating_add(2);
         let before = self.sent_history.len();
-        self.sent_history.retain(|f| !f.is_retransmittable || f.retries <= grace);
+        self.sent_history.retain(|_, f| !f.is_retransmittable || f.retries <= grace);
         let evicted = before - self.sent_history.len();
         if evicted > 0 {
             tracing::debug!("Evicted {} zombie frames from sent_history (remaining={})", evicted, self.sent_history.len());
         }
 
         // ── Retransmit expired frames ────────────────────────────────
-        // Limit retransmits per tick to prevent bandwidth saturation
+        // Backoff starts from retry #0 (immediately effective):
+        //   effective_rto = base_rto * 2^retries, capped at 2^6 = 64×
+        // This ensures we do not flood with retransmits on the first few losses
+        // while still recovering quickly on a transient single loss.
         let mut retransmit_budget: usize = self.cc.retransmit_budget();
-        for frame in self.sent_history.iter_mut() {
+        for frame in self.sent_history.values_mut() {
             if !frame.is_retransmittable {
                 continue;
             }
 
-            let retry_over = frame.retries.saturating_sub(self.max_retries);
+            let backoff_factor = 1u64 << (frame.retries as u64).min(6);
-            let backoff_factor = 1u64 << retry_over.min(6);
             let effective_rto = Duration::from_millis(base_rto_ms.saturating_mul(backoff_factor));
 
             if now.duration_since(frame.last_sent) >= effective_rto {
@@ -672,7 +662,7 @@ impl ProtocolMachine {
     }
 
     fn lookup_sent_frame(&mut self, nonce: u64) -> Option<Bytes> {
-        if let Some(frame) = self.sent_history.iter_mut().rev().find(|f| f.nonce == nonce) {
+        if let Some(frame) = self.sent_history.get_mut(&nonce) {
             frame.last_sent = Instant::now();
             frame.retries = frame.retries.saturating_add(1);
             return Some(frame.bytes.clone());
@@ -684,7 +674,7 @@ impl ProtocolMachine {
         if is_retransmittable {
             self.cc.on_send(bytes.len() as u64);
         }
-        self.sent_history.push_back(SentFrame {
+        self.sent_history.insert(nonce, SentFrame {
             nonce,
             bytes,
             last_sent: Instant::now(),
@@ -697,7 +687,7 @@ impl ProtocolMachine {
                 overflow, self.max_sent_history
             );
             while self.sent_history.len() > self.max_sent_history {
-                self.sent_history.pop_front();
+                self.sent_history.pop_first();
             }
         }
     }
@@ -708,8 +698,8 @@ impl ProtocolMachine {
         let mut min_rtt = Duration::from_secs(60);
 
         // Compute RTT from the oldest acked frame's send timestamp
-        for frame in self.sent_history.iter() {
+        for (&nonce, frame) in &self.sent_history {
-            if nonce_in_ranges(frame.nonce, ranges) {
+            if nonce_in_ranges(nonce, ranges) {
                 acked_bytes += frame.bytes.len() as u64;
                 let rtt = now.duration_since(frame.last_sent);
                 if rtt < min_rtt {
@@ -718,7 +708,7 @@ impl ProtocolMachine {
             }
         }
 
-        self.sent_history.retain(|frame| !nonce_in_ranges(frame.nonce, ranges));
+        self.sent_history.retain(|&nonce, _| !nonce_in_ranges(nonce, ranges));
 
         // Notify congestion controller
         if acked_bytes > 0 {

ostp-flutter/android/app/src/main/kotlin/com/ospab/ostp_client/MainActivity.kt

@@ -95,6 +95,15 @@ class MainActivity : FlutterActivity() {
                         result.error("ERROR", e.message, null)
                     }
                 }
+                "runDnsProber" -> {
+                    try {
+                        val domain = call.argument<String>("domain") ?: "example.com"
+                        val json = net.ostp.client.OstpClientSdk.nativeRunDnsProber(domain)
+                        result.success(json)
+                    } catch (e: Throwable) {
+                        result.error("ERROR", e.message, null)
+                    }
+                }
                 "getInstalledApps" -> {
                     try {
                         val pm = packageManager

ostp-flutter/android/app/src/main/kotlin/net/ostp/client/OstpClientSdk.kt

@@ -50,4 +50,8 @@ object OstpClientSdk {
     @Keep
     @JvmStatic
     external fun notifyNetworkChanged()
+
+    @Keep
+    @JvmStatic
+    external fun nativeRunDnsProber(domain: String): String
 }

ostp-flutter/lib/main.dart

@@ -26,11 +26,11 @@ class OstpApp extends StatelessWidget {
       debugShowCheckedModeBanner: false,
       theme: ThemeData(
         brightness: Brightness.dark,
-        scaffoldBackgroundColor: const Color(0xFF08080F),
+        scaffoldBackgroundColor: const Color(0xFF030303),
         colorScheme: const ColorScheme.dark(
-          primary: Color(0xFF6C72FF),
+          primary: Color(0xFFF9FAFB),
-          secondary: Color(0xFF22D3A5),
+          secondary: Color(0xFF10B981),
-          surface: Color(0xFF151522),
+          surface: Color(0xFF09090B),
         ),
         fontFamily: 'Inter',
         useMaterial3: true,

ostp-flutter/lib/ui/home_screen.dart

@@ -6,6 +6,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 import 'package:mobile_scanner/mobile_scanner.dart';
+import 'package:flutter_svg/flutter_svg.dart';
 import '../models/connection_state_enum.dart';
 import 'settings_screen.dart';
 import 'logs_screen.dart';
@@ -517,31 +518,16 @@ class _HomeScreenState extends State<HomeScreen> with TickerProviderStateMixin {
     return Scaffold(
       body: Stack(
         children: [
-          Positioned(
+          Center(
-            top: -150, right: -100,
+            child: Opacity(
-            child: Container(
+              opacity: theme.brightness == Brightness.dark ? 0.05 : 0.06,
-              width: 400, height: 400,
+              child: SvgPicture.asset(
-              decoration: BoxDecoration(
+                'assets/logo.svg',
-                shape: BoxShape.circle,
+                width: MediaQuery.of(context).size.width * 0.8,
-                color: theme.colorScheme.primary.withOpacity(0.15),
+                fit: BoxFit.contain,
-              ),
+                colorFilter: theme.brightness == Brightness.light 
-              child: BackdropFilter(
+                    ? const ColorFilter.mode(Colors.black, BlendMode.srcIn) 
-                filter: ImageFilter.blur(sigmaX: 100, sigmaY: 100),
+                    : null,
-                child: Container(),
-              ),
-            ),
-          ),
-          Positioned(
-            bottom: -100, left: -100,
-            child: Container(
-              width: 350, height: 350,
-              decoration: BoxDecoration(
-                shape: BoxShape.circle,
-                color: theme.colorScheme.secondary.withOpacity(0.1),
-              ),
-              child: BackdropFilter(
-                filter: ImageFilter.blur(sigmaX: 100, sigmaY: 100),
-                child: Container(),
               ),
             ),
           ),

ostp-flutter/lib/ui/settings_screen.dart

@@ -38,7 +38,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
 
   bool _obscureKey = true;
   bool _debugMode = false;
-  String _dnsRegion = 'Global';
+  late TextEditingController _dnsRegionCtrl;
   String _transportMode = 'udp'; // 'udp' | 'uot'
   String _tunStack = 'ostp'; // 'system' | 'ostp'
   bool _muxEnabled = false;
@@ -58,9 +58,9 @@ class _SettingsScreenState extends State<SettingsScreen> {
     _ipsCtrl = TextEditingController(text: widget.prefs.getString('ex_ips') ?? '');
     _processesCtrl = TextEditingController(text: widget.prefs.getString('ex_processes') ?? '');
     _dnsDomainCtrl = TextEditingController(text: widget.prefs.getString('dns_domain') ?? '');
-    _pbkCtrl = TextEditingController(text: widget.prefs.getString('pbk') ?? '');
+    _dnsRegionCtrl = TextEditingController(text: widget.prefs.getString('dns_region') ?? '1.1.1.1');
+    _pbkCtrl = TextEditingController(text: widget.prefs.getString('tun_pbk') ?? '');
     _sidCtrl = TextEditingController(text: widget.prefs.getString('sid') ?? '');
-    _dnsRegion = widget.prefs.getString('dns_region') ?? 'Global';
     _transportMode = widget.prefs.getString('transport_mode') ?? 'udp';
     _tunStack = widget.prefs.getString('tun_stack') ?? 'ostp';
     _debugMode = widget.prefs.getBool('debug_mode') ?? false;
@@ -81,6 +81,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
     _ipsCtrl.dispose();
     _processesCtrl.dispose();
     _dnsDomainCtrl.dispose();
+    _dnsRegionCtrl.dispose();
     _pbkCtrl.dispose();
     _sidCtrl.dispose();
     _muxSessionsCtrl.dispose();
@@ -97,11 +98,11 @@ class _SettingsScreenState extends State<SettingsScreen> {
     widget.prefs.setString('ex_ips', _ipsCtrl.text.trim());
     widget.prefs.setString('ex_processes', _processesCtrl.text.trim());
     widget.prefs.setBool('debug_mode', _debugMode);
-    widget.prefs.setString('dns_region', _dnsRegion);
     widget.prefs.setString('transport_mode', _transportMode);
     widget.prefs.setString('tun_stack', _tunStack);
     widget.prefs.setString('dns_domain', _dnsDomainCtrl.text.trim());
-    widget.prefs.setString('pbk', _pbkCtrl.text.trim());
+    widget.prefs.setString('dns_region', _dnsRegionCtrl.text.trim());
+    widget.prefs.setString('tun_pbk', _pbkCtrl.text.trim());
     widget.prefs.setString('sid', _sidCtrl.text.trim());
     widget.prefs.setBool('mux_enabled', _muxEnabled);
     widget.prefs.setString('mux_sessions', _muxSessionsCtrl.text.trim());
@@ -237,7 +238,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
                       _serverCtrl.text = host;
                       _keyCtrl.text = key;
                       _dnsDomainCtrl.text = uri.queryParameters['domain'] ?? '';
-                      _dnsRegion = uri.queryParameters['region'] ?? 'Global';
+                      _dnsRegionCtrl.text = uri.queryParameters['resolver'] ?? '1.1.1.1';
                       
                       final type = uri.queryParameters['type'];
                       _transportMode = type == 'tcp' || type == 'http' ? 'uot' : (type == 'dns' ? 'dns' : 'udp');
@@ -349,30 +350,27 @@ class _SettingsScreenState extends State<SettingsScreen> {
                         const SizedBox(height: 16),
                         _buildTextField('Domain (Points to Server)', _dnsDomainCtrl, hint: 'tunnel.myvpn.com'),
                         const SizedBox(height: 16),
-                        DropdownButtonFormField<String>(
+                        Row(
-                          value: _dnsRegion,
+                          children: [
-                          dropdownColor: const Color(0xFF1E1E2C),
+                            Expanded(
-                          style: const TextStyle(color: Colors.white, fontSize: 14),
+                              child: _buildTextField('DNS Resolver Server', _dnsRegionCtrl, hint: '1.1.1.1'),
-                          decoration: InputDecoration(
+                            ),
-                            labelText: 'DNS Resolver Region',
+                            const SizedBox(width: 8),
-                            labelStyle: const TextStyle(color: Colors.white54, fontSize: 13),
+                            Padding(
-                            border: OutlineInputBorder(borderRadius: BorderRadius.circular(12)),
+                              padding: const EdgeInsets.only(top: 24.0),
-                            contentPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
+                              child: ElevatedButton(
-                          ),
+                                onPressed: _showDnsProberDialog,
-                          items: ['Global', 'Russia', 'China', 'Iran'].map((String region) {
+                                style: ElevatedButton.styleFrom(
-                            return DropdownMenuItem<String>(
+                                  backgroundColor: Colors.orangeAccent.withOpacity(0.2),
-                              value: region,
+                                  foregroundColor: Colors.orangeAccent,
-                              child: Text(region),
+                                  elevation: 0,
-                            );
+                                  padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 14),
-                          }).toList(),
+                                  shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
-                          onChanged: (String? newValue) {
+                                ),
-                            if (newValue != null) {
+                                child: const Text('PROBER', style: TextStyle(fontWeight: FontWeight.bold, fontSize: 12)),
-                              setState(() {
+                              ),
-                                _dnsRegion = newValue;
+                            )
-                                _saveSettings();
+                          ],
-                              });
-                            }
-                          },
                         ),
                       ],
                     ),
@@ -529,8 +527,9 @@ class _SettingsScreenState extends State<SettingsScreen> {
     if (_dnsDomainCtrl.text.trim().isNotEmpty) {
       queryParams.add('domain=${Uri.encodeComponent(_dnsDomainCtrl.text.trim())}');
     }
-    if (_dnsRegion != 'Global') {
+    final resolver = _dnsRegionCtrl.text.trim();
-      queryParams.add('region=${Uri.encodeComponent(_dnsRegion)}');
+    if (resolver.isNotEmpty && resolver != '1.1.1.1') {
+      queryParams.add('resolver=${Uri.encodeComponent(resolver)}');
     }
     if (_pbkCtrl.text.trim().isNotEmpty) {
       queryParams.add('pbk=${Uri.encodeComponent(_pbkCtrl.text.trim())}');
@@ -603,6 +602,97 @@ class _SettingsScreenState extends State<SettingsScreen> {
     );
   }
 
+  Future<void> _showDnsProberDialog() async {
+    const channel = MethodChannel('com.ospab.ostp/vpn');
+    showDialog(
+      context: context,
+      barrierDismissible: false,
+      builder: (context) {
+        return StatefulBuilder(
+          builder: (context, setModalState) {
+            return AlertDialog(
+              backgroundColor: Theme.of(context).colorScheme.surface,
+              shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
+              title: const Text('DNS Prober', textAlign: TextAlign.center),
+              content: FutureBuilder<String?>(
+                future: channel.invokeMethod<String>('runDnsProber', {'domain': _dnsDomainCtrl.text.trim()}),
+                builder: (context, snapshot) {
+                  if (snapshot.connectionState == ConnectionState.waiting) {
+                    return const Column(
+                      mainAxisSize: MainAxisSize.min,
+                      children: [
+                        CircularProgressIndicator(),
+                        SizedBox(height: 16),
+                        Text('Sending real tunnel probes...', style: TextStyle(color: Colors.white54, fontSize: 13), textAlign: TextAlign.center),
+                      ],
+                    );
+                  }
+
+                  if (snapshot.hasError || !snapshot.hasData) {
+                    return Text('Error: ${snapshot.error}', style: const TextStyle(color: Colors.redAccent));
+                  }
+
+                  List<dynamic> results = [];
+                  try {
+                    results = jsonDecode(snapshot.data!);
+                  } catch (_) {}
+
+                  if (results.isEmpty) {
+                    return const Text('No results or all timed out.', style: TextStyle(color: Colors.redAccent));
+                  }
+
+                  return SizedBox(
+                    width: double.maxFinite,
+                    child: ListView.builder(
+                      shrinkWrap: true,
+                      itemCount: results.length,
+                      itemBuilder: (context, index) {
+                        final res = results[index];
+                        final name = res['name'] ?? '';
+                        final ip = res['ip'] ?? '';
+                        final latency = res['latency_ms'];
+                        
+                        final isBest = index == 0 && latency != null;
+                        
+                        return ListTile(
+                          onTap: latency != null ? () {
+                            setState(() {
+                              _dnsRegionCtrl.text = ip;
+                              _saveSettings();
+                            });
+                            Navigator.pop(context);
+                            ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text('DNS set to $ip')));
+                          } : null,
+                          title: Text('${isBest ? '⭐ ' : ''}$name', style: const TextStyle(fontSize: 14)),
+                          subtitle: Text(ip, style: const TextStyle(fontSize: 12, color: Colors.white54)),
+                          trailing: Text(
+                            latency != null ? '$latency ms' : 'TIMEOUT',
+                            style: TextStyle(
+                              color: latency == null ? Colors.redAccent : (latency < 100 ? Colors.greenAccent : Colors.orangeAccent),
+                              fontWeight: FontWeight.bold,
+                            ),
+                          ),
+                          tileColor: isBest ? Colors.blueAccent.withOpacity(0.1) : null,
+                          shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(10)),
+                        );
+                      },
+                    ),
+                  );
+                },
+              ),
+              actions: [
+                TextButton(
+                  onPressed: () => Navigator.pop(context),
+                  child: const Text('Close'),
+                )
+              ],
+            );
+          }
+        );
+      }
+    );
+  }
+
   Future<void> _checkForUpdates() async {
     if (_isCheckingUpdates) return;
     setState(() { _isCheckingUpdates = true; });

ostp-flutter/pubspec.lock

@@ -134,6 +134,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.0"
+  flutter_svg:
+    dependency: "direct main"
+    description:
+      name: flutter_svg
+      sha256: "35882981abcbfb8c15b286f0cd690ff25bac12d95eff3e25ee207f37d4c42e7f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.0"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -272,6 +280,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.9.1"
+  path_parsing:
+    dependency: transitive
+    description:
+      name: path_parsing
+      sha256: "883402936929eac138ee0a45da5b0f2c80f89913e6dc3bf77eb65b84b409c6ca"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
   path_provider_linux:
     dependency: transitive
     description:
@@ -581,6 +597,30 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.1.5"
+  vector_graphics:
+    dependency: transitive
+    description:
+      name: vector_graphics
+      sha256: "2306c03da2ba81724afeb589c351ebbc0aa7d86005925be8f8735856dbe5e42d"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.2"
+  vector_graphics_codec:
+    dependency: transitive
+    description:
+      name: vector_graphics_codec
+      sha256: "99fd9fbd34d9f9a32efd7b6a6aae14125d8237b10403b422a6a6dfeac2806146"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.13"
+  vector_graphics_compiler:
+    dependency: transitive
+    description:
+      name: vector_graphics_compiler
+      sha256: "142a9146f447d15b10bdc00e21d5f4d83e5b32bb5f8f8f5a04c75311344923a3"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.6"
   vector_math:
     dependency: transitive
     description:

ostp-flutter/pubspec.yaml

@@ -16,7 +16,7 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 # In Windows, build-name is used as the major, minor, and patch parts
 # of the product and file versions while build-number is used as the build suffix.
-version: 0.3.7+20
+version: 0.3.12+25
 
 environment:
   sdk: ^3.11.4
@@ -34,6 +34,7 @@ dependencies:
   # The following adds the Cupertino Icons font to your application.
   # Use with the CupertinoIcons class for iOS style icons.
   cupertino_icons: ^1.0.8
+  flutter_svg: ^2.0.10
   shared_preferences: ^2.5.5
   mobile_scanner: ^5.0.0
   window_manager: ^0.5.1
@@ -72,9 +73,8 @@ flutter:
   uses-material-design: true
 
   # To add assets to your application, add an assets section, like this:
-  # assets:
+  assets:
-  #   - images/a_dot_burr.jpeg
+    - assets/logo.svg
-  #   - images/a_dot_ham.jpeg
 
   # An image asset can refer to one or more resolution-specific "variants", see
   # https://flutter.dev/to/resolution-aware-images

ostp-gui/src-tauri/Cargo.lock

@@ -2665,7 +2665,7 @@ dependencies = [
 
 [[package]]
 name = "ostp-client"
-version = "0.2.98"
+version = "0.3.12"
 dependencies = [
  "anyhow",
  "base64 0.22.1",
@@ -2700,17 +2700,20 @@ dependencies = [
 
 [[package]]
 name = "ostp-core"
-version = "0.2.98"
+version = "0.3.12"
 dependencies = [
  "anyhow",
+ "byteorder",
  "bytes",
  "chacha20poly1305",
  "hkdf",
  "hmac",
  "rand",
+ "serde",
  "sha2",
  "snow",
  "thiserror 1.0.69",
+ "tokio",
  "tracing",
  "x25519-dalek",
 ]
@@ -2720,12 +2723,16 @@ name = "ostp-gui"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "chacha20poly1305",
+ "hex",
  "json_comments",
  "ostp-client",
+ "ostp-core",
  "portable-atomic",
  "rand",
  "serde",
  "serde_json",
+ "sha2",
  "tauri",
  "tauri-build",
  "tauri-plugin-opener",
@@ -2735,7 +2742,7 @@ dependencies = [
 
 [[package]]
 name = "ostp-tun"
-version = "0.2.98"
+version = "0.3.12"
 dependencies = [
  "anyhow",
  "libc",

ostp-gui/src-tauri/Cargo.toml

@@ -26,6 +26,7 @@ tokio = { version = "1", features = ["full"] }
 anyhow = "1"
 tracing = "0.1"
 ostp-client = { path = "../../ostp-client" }
+ostp-core = { path = "../../ostp-core" }
 portable-atomic = "1"
 json_comments = "0.2"
 rand = "0.8"

ostp-gui/src-tauri/permissions/app-commands.toml

@@ -6,11 +6,15 @@ description = "Enables access to core OSTP commands"
 allow = [
   "start_tunnel",
   "stop_tunnel",
+  "reload_tunnel",
   "get_tunnel_status",
   "get_metrics",
   "get_config",
   "save_config",
   "get_wintun_install_path",
   "set_autostart",
-  "get_autostart"
+  "get_autostart",
+  "list_running_processes",
+  "kill_auto_search",
+  "run_dns_prober"
 ]

ostp-gui/src-tauri/src/dns_prober.rs

@@ -0,0 +1,6 @@
+use ostp_core::dns_prober::{run_dns_prober as core_run_dns_prober, DnsProbeResult};
+
+#[tauri::command]
+pub async fn run_dns_prober(domain: String) -> Result<Vec<DnsProbeResult>, String> {
+    core_run_dns_prober(&domain).await
+}

ostp-gui/src-tauri/src/ipc_crypto.rs

@@ -1,41 +1,3 @@
-use anyhow::{anyhow, Result};
+// Re-export the shared IPC crypto from ostp-client so that GUI and tun-helper
-use chacha20poly1305::{ChaCha20Poly1305, Nonce};
+// always use identical encrypt/decrypt logic.
-use chacha20poly1305::aead::{Aead, KeyInit};
+pub use ostp_client::ipc_crypto::{derive_key, IpcCrypto};
-use sha2::{Sha256, Digest};
-
-pub struct IpcCrypto {
-    cipher: ChaCha20Poly1305,
-    nonce: [u8; 12],
-}
-
-impl IpcCrypto {
-    pub fn new(key: &[u8; 32]) -> Self {
-        let cipher = ChaCha20Poly1305::new_from_slice(key)
-            .expect("valid key size");
-        let nonce = [0u8; 12];
-        Self { cipher, nonce }
-    }
-
-    pub fn encrypt(&self, plaintext: &[u8]) -> Result<Vec<u8>> {
-        let nonce = Nonce::from_slice(&self.nonce);
-        let ciphertext = self.cipher.encrypt(nonce, plaintext)
-            .map_err(|e| anyhow!("Encryption failed: {}", e))?;
-        Ok(ciphertext)
-    }
-
-    pub fn decrypt(&self, ciphertext: &[u8]) -> Result<Vec<u8>> {
-        let nonce = Nonce::from_slice(&self.nonce);
-        let plaintext = self.cipher.decrypt(nonce, ciphertext)
-            .map_err(|e| anyhow!("Decryption failed: {}", e))?;
-        Ok(plaintext)
-    }
-}
-
-pub fn derive_key(token: &str) -> [u8; 32] {
-    let mut hasher = Sha256::new();
-    hasher.update(token.as_bytes());
-    let result = hasher.finalize();
-    let mut key = [0u8; 32];
-    key.copy_from_slice(&result);
-    key
-}

ostp-gui/src-tauri/src/lib.rs

@@ -8,6 +8,7 @@ use portable_atomic::Ordering;
 use tauri::Emitter;
 
 mod ipc_crypto;
+mod dns_prober;
 
 // ── Config types ─────────────────────────────────────────────────────────────
 
@@ -39,7 +40,7 @@ struct UIMetrics {
 #[serde(tag = "type", rename_all = "lowercase")]
 enum HelperMsg {
     Status { value: u8 },
-    Log { message: String },
+    Log { #[allow(dead_code)] message: String },
     Metrics { bytes_sent: u64, bytes_recv: u64, rtt_ms: u32 },
     Error { message: String },
 }
@@ -58,6 +59,7 @@ struct HelperState {
     pipe_state: Arc<Mutex<HelperPipeState>>,
     cmd_tx: tokio::sync::mpsc::Sender<String>,
     token: String,
+    #[allow(dead_code)]
     port: u16,
 }
 
@@ -778,7 +780,7 @@ static SINGLE_INSTANCE_LOCK: std::sync::OnceLock<std::net::TcpListener> = std::s
 pub fn run() {
     if let Ok(listener) = std::net::TcpListener::bind("127.0.0.1:49153") {
         let _ = SINGLE_INSTANCE_LOCK.set(listener);
-    } else {
+    } else if !cfg!(debug_assertions) {
         show_error_dialog("Приложение OSTP GUI уже запущено!");
         return;
     }
@@ -874,7 +876,7 @@ pub fn run() {
             }
             _ => {}
         })
-        .invoke_handler(tauri::generate_handler![start_tunnel, stop_tunnel, reload_tunnel, get_tunnel_status, get_metrics, get_config, save_config, get_wintun_install_path, set_autostart, get_autostart, list_running_processes])
+        .invoke_handler(tauri::generate_handler![start_tunnel, stop_tunnel, reload_tunnel, get_tunnel_status, get_metrics, get_config, save_config, get_wintun_install_path, set_autostart, get_autostart, list_running_processes, dns_prober::run_dns_prober])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");
 }

ostp-gui/src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "ostp-gui",
-  "version": "0.3.7",
+  "version": "0.3.12",
   "identifier": "com.ospab.ostp",
   "build": {
     "frontendDist": "../src"

ostp-gui/src/index.html

@@ -12,10 +12,9 @@
 <body>
   <div class="app-root">
 
-    <!-- Ambient light blobs -->
+    <!-- Eagle Watermark -->
-    <div class="ambient" aria-hidden="true">
+    <div class="watermark" aria-hidden="true">
-      <div class="blob blob-1"></div>
+      <img src="assets/logo.svg" alt="" />
-      <div class="blob blob-2"></div>
     </div>
 
     <!-- ── HOME SCREEN ──────────────────────────────────────────── -->
@@ -202,24 +201,20 @@
             </select>
           </div>
 
-          <div id="group-dns-proxy" style="display: none;">
+          <div id="group-dns-proxy" style="display: none; flex-direction: column; gap: 14px;">
             <div class="field-group">
               <label class="field-label" for="in-dns-domain" style="color: var(--c-warning);" data-i18n="label_dns_domain">Domain (Points to Server)</label>
               <input id="in-dns-domain" class="field-input" type="text" placeholder="tunnel.myvpn.com" spellcheck="false" />
-              <div style="font-size: 0.8rem; color: var(--c-sub); margin-top: 4px;">
-                <span data-i18n="dns_domain_hint">This is the "last resort" over public DNS servers. You need a domain pointing to your server (NS/A record).</span>
-                <span data-i18n="dns_guide">Detailed setup guide available in</span> <a href="https://github.com/ospab/ostp/wiki/DNS-Transport" target="_blank" style="color: var(--c-accent)" data-i18n="wiki_link">GitHub Wiki</a>.
-              </div>
             </div>
 
             <div class="field-group">
-              <label class="field-label" for="in-dns-region" data-i18n="label_dns_region">DNS Resolver Region (Prober)</label>
+              <label class="field-label" for="in-dns-region" data-i18n="label_dns_region">DNS Resolver Server</label>
-              <select id="in-dns-region" class="field-input">
+              <div class="input-wrap">
-                <option value="Global" data-i18n="opt_global">Global (Cloudflare, Google, etc)</option>
+                <input id="in-dns-region" class="field-input" type="text" placeholder="1.1.1.1" spellcheck="false" />
-                <option value="Russia" data-i18n="opt_russia">Russia (Yandex, VK, etc)</option>
+                <button id="btn-dns-prober" class="peek-btn" tabindex="-1" title="Find fastest DNS server" style="width:auto; padding: 0 8px; font-size: 0.7rem; color: var(--c-accent);">
-                <option value="China" data-i18n="opt_china">China (AliDNS, DNSPod, etc)</option>
+                  PROBER
-                <option value="Iran" data-i18n="opt_iran">Iran (Shatel, Electro, etc)</option>
+                </button>
-              </select>
+              </div>
             </div>
           </div>
 
@@ -380,6 +375,23 @@
         </div>
       </div>
     </div>
+      </div>
+    </div>
+
+    <!-- DNS Prober Modal -->
+    <div id="dns-prober-modal" class="modal-overlay hidden">
+      <div class="modal-content" style="min-width: 300px; max-width: 420px;">
+        <h3 class="modal-title">DNS Prober</h3>
+        <p class="modal-text" style="font-size: 0.8rem; color: var(--c-txt-2); margin-bottom: 12px;">
+          Sends a real DNS tunnel probe through each resolver and measures the round-trip time to your server. The fastest one is selected automatically.
+        </p>
+        <div id="prober-status" style="font-size: 0.75rem; color: var(--c-accent); margin-bottom: 10px; min-height: 18px;"></div>
+        <div id="prober-list" style="display: flex; flex-direction: column; gap: 5px; max-height: 280px; overflow-y: auto;"></div>
+        <div class="modal-actions" style="margin-top: 16px;">
+          <button id="btn-prober-close" class="btn secondary">Close</button>
+        </div>
+      </div>
+    </div>
 
   </div>
   <script type="module" src="main.js"></script>