Update release.yml

ME Healthcheck + Keepalives + Concurrency

.github/workflows/release.yml

@@ -0,0 +1,135 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - '[0-9]+.[0-9]+.[0-9]+'  # Matches tags like 3.0.0, 3.1.2, etc.
+  workflow_dispatch:  # Manual trigger from GitHub Actions UI
+
+permissions:
+  contents: read
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build:
+    name: Build ${{ matrix.target }}
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - target: x86_64-unknown-linux-gnu
+            artifact_name: telemt
+            asset_name: telemt-x86_64-linux-gnu
+          - target: aarch64-unknown-linux-gnu
+            artifact_name: telemt
+            asset_name: telemt-aarch64-linux-gnu
+          - target: x86_64-unknown-linux-musl
+            artifact_name: telemt
+            asset_name: telemt-x86_64-linux-musl
+          - target: aarch64-unknown-linux-musl
+            artifact_name: telemt
+            asset_name: telemt-aarch64-linux-musl
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - name: Install stable Rust toolchain
+        uses: dtolnay/rust-toolchain@888c2e1ea69ab0d4330cbf0af1ecc7b68f368cc1 # v1
+        with:
+          toolchain: stable
+          targets: ${{ matrix.target }}
+
+      - name: Install cross-compilation tools
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y gcc-aarch64-linux-gnu
+
+      - name: Cache cargo registry & build artifacts
+        uses: actions/cache@d4323d4df104b026a6aa633fdb11d772146be0bf # v4.2.2
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-${{ matrix.target }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-${{ matrix.target }}-cargo-
+
+      - name: Install cross
+        run: cargo install cross --git https://github.com/cross-rs/cross
+
+      - name: Build Release
+        env:
+          RUSTFLAGS: ${{ contains(matrix.target, 'musl') && '-C target-feature=+crt-static' || '' }}
+        run: cross build --release --target ${{ matrix.target }}
+
+      - name: Package binary
+        run: |
+          cd target/${{ matrix.target }}/release
+          tar -czvf ${{ matrix.asset_name }}.tar.gz ${{ matrix.artifact_name }}
+          sha256sum ${{ matrix.asset_name }}.tar.gz > ${{ matrix.asset_name }}.sha256
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@65c4c4a1ddee5b72f698fdd19549f0f0fb45cf08 # v4.6.0
+        with:
+          name: ${{ matrix.asset_name }}
+          path: |
+            target/${{ matrix.target }}/release/${{ matrix.asset_name }}.tar.gz
+            target/${{ matrix.target }}/release/${{ matrix.asset_name }}.sha256
+
+  release:
+    name: Create Release
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          fetch-depth: 0
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Download all artifacts
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
+        with:
+          path: artifacts
+
+      - name: Update version in Cargo.toml and Cargo.lock
+        run: |
+          # Extract version from tag (remove 'v' prefix if present)
+          VERSION="${GITHUB_REF#refs/tags/}"
+          VERSION="${VERSION#v}"
+          
+          # Install cargo-edit for version bumping
+          cargo install cargo-edit
+          
+          # Update Cargo.toml version
+          cargo set-version "$VERSION"
+          
+          # Configure git
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          
+          # Commit and push changes
+          #git add Cargo.toml Cargo.lock
+          #git commit -m "chore: bump version to $VERSION" || echo "No changes to commit"
+          #git push origin HEAD:main
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Create Release
+        uses: softprops/action-gh-release@v2
+        with:
+          files: artifacts/**/*
+          generate_release_notes: true
+          draft: false
+          prerelease: ${{ contains(github.ref, '-rc') || contains(github.ref, '-beta') || contains(github.ref, '-alpha') }}

CONTRIBUTING.md

@@ -0,0 +1,5 @@
+## Pull Requests - Rules
+- ONLY signed and verified commits
+- ONLY from your name
+- DO NOT commit with `codex` or `claude` as author/commiter
+- PREFER `flow` branch for development, not `main`

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "telemt"
-version = "3.0.1"
+version = "3.0.4"
 edition = "2024"
 
 [dependencies]

LICENSING.md

@@ -0,0 +1,17 @@
+# LICENSING
+## Licenses for Versions
+| Version | License       |
+|---------|---------------|
+| 1.0     | NO LICNESE    |
+| 1.1     | NO LICENSE    |
+| 1.2     | NO LICENSE    |
+| 2.0     | NO LICENSE    |
+| 3.0     | TELEMT UL 1   |
+
+### License Types
+- **NO LICENSE** = ***ALL RIGHT RESERVED***
+- **TELEMT UL1** - work in progress license for source code of `telemt`, which encourages:
+  - fair use, 
+  - contributions, 
+  - distribution, 
+  - but prohibits NOT mentioning the authors

README.md

@@ -10,74 +10,40 @@
 
 ### 🇷🇺 RU
 
-15 февраля мы опубликовали `telemt 3` с поддержкой Middle-End Proxy, а значит:
+18 февраля мы опубликовали `telemt 3.0.3`, он имеет:
 
-- с функциональными медиа, в том числе с CDN/DC=203  
-- с Ad-tag — показывайте спонсорский канал и собирайте статистику через официального бота  
-- с новым подходом к безопасности и асинхронности  
-- с высокоточной диагностикой криптографии через `ME_DIAG`  
+- улучшенный механизм Middle-End Health Check
+- высокоскоростное восстановление инициализации Middle-End
+- меньше задержек на hot-path
+- более корректную работу в Dualstack, а именно - IPv6 Middle-End
+- аккуратное переподключение клиента без дрифта сессий между Middle-End
+- автоматическая деградация на Direct-DC при массовой (>2 ME-DC-групп) недоступности Middle-End
+- автодетект IP за NAT, при возможности - будет выполнен хендшейк с ME, при неудаче - автодеградация
+- единственный известный специальный DC=203 уже добавлен в код: медиа загружаются с CDN в Direct-DC режиме
 
-Для использования нужно:
+[Здесь вы можете найти релиз](https://github.com/telemt/telemt/releases/tag/3.0.3)
 
-1. Версия `telemt` ≥3.0.0
-2. Выполнение любого из наборов условий:
-   - публичный IP для исходящих соединений установлен на интерфейса инстанса с `telemt`
-     - ЛИБО
-   - вы используете NAT 1:1 + включили STUN-пробинг
-3. В конфиге, в секции `[general]` указать:
-```toml
-use_middle_proxy = true
-```
-
-Если условия из пункта 1 не выполняются:
-1. Выключите ME-режим:
-   - установите `use_middle_proxy = false`
-     - ЛИБО
-   - Middle-End Proxy будет выключен автоматически по таймауту, но это займёт больше времени при запуске
-2. В конфиге, добавьте в конец:
-```toml
-[dc_overrides]
-"203" = "91.105.192.100:443"
-```
-
-Если у вас есть компетенции в асинхронных сетевых приложениях, анализе трафика, реверс-инжиниринге или сетевых расследованиях — мы открыты к идеям и pull requests.
+Если у вас есть компетенции в асинхронных сетевых приложениях, анализе трафика, реверс-инжиниринге или сетевых расследованиях - мы открыты к идеям и pull requests!
 
 </td>
 <td width="50%" valign="top">
 
 ### 🇬🇧 EN
 
-On February 15, we released `telemt 3` with support for Middle-End Proxy, which means:
+On February 18, we released `telemt 3.0.3`. This version introduces:
 
-- functional media, including CDN/DC=203  
-- Ad-tag support – promote a sponsored channel and collect statistics via Telegram bot  
-- new approach to security and asynchronicity  
-- high-precision cryptography diagnostics via `ME_DIAG`  
+- improved Middle-End Health Check method  
+- high-speed recovery of Middle-End init
+- reduced latency on the hot path  
+- correct Dualstack support: proper handling of IPv6 Middle-End  
+- *clean* client reconnection without session "drift" between Middle-End
+- automatic degradation to Direct-DC mode in case of large-scale (>2 ME-DC groups) Middle-End unavailability  
+- automatic public IP detection behind NAT; first - Middle-End handshake is performed, otherwise automatic degradation is applied  
+- known special DC=203 is now handled natively: media is delivered from the CDN via Direct-DC mode  
 
-To use this feature, the following requirements must be met:
-1. `telemt` version ≥ 3.0.0
-2. One of the following conditions satisfied:
-   - the instance running `telemt` has a public IP address assigned to its network interface for outbound connections  
-     - OR
-   - you are using 1:1 NAT and have STUN probing enabled  
-3. In the config file, under the `[general]` section, specify:
-```toml
-use_middle_proxy = true
-````
+[Release is available here](https://github.com/telemt/telemt/releases/tag/3.0.3)
 
-If the conditions from step 1 are not satisfied:
-1. Disable Middle-End mode:
-   - set `use_middle_proxy = false`
-     - OR
-   - Middle-End Proxy will be disabled automatically after a timeout, but this will increase startup time
-
-2. In the config file, add the following at the end:
-```toml
-[dc_overrides]
-"203" = "91.105.192.100:443"
-```
-
-If you have expertise in asynchronous network applications, traffic analysis, reverse engineering, or network forensics — we welcome ideas, suggestions, and pull requests.
+If you have expertise in asynchronous network applications, traffic analysis, reverse engineering, or network forensics - we welcome ideas and pull requests!
 
 </td>
 </tr>
@@ -86,7 +52,9 @@ If you have expertise in asynchronous network applications, traffic analysis, re
 # Features
 💥 The configuration structure has changed since version 1.1.0.0. change it in your environment!
 
-⚓ Our implementation of **TLS-fronting** is one of the most deeply debugged, focused, advanced and *almost* **"behaviorally consistent to real"**:  we are confident we have it right - [see evidence on our validation and traces](#recognizability-for-dpi-and-crawler) 
+⚓ Our implementation of **TLS-fronting** is one of the most deeply debugged, focused, advanced and *almost* **"behaviorally consistent to real"**:  we are confident we have it right - [see evidence on our validation and traces](#recognizability-for-dpi-and-crawler)
+
+⚓ Our ***Middle-End Pool*** is fastest by design in standard scenarios, compared to other implementations of connecting to the Middle-End Proxy: non dramatically, but usual
 
 # GOTO
 - [Features](#features)
@@ -210,10 +178,18 @@ then Ctrl+X -> Y -> Enter to save
 ```toml
 # === General Settings ===
 [general]
+# prefer_ipv6 is deprecated; use [network].prefer
 prefer_ipv6 = false
 fast_mode = true
 use_middle_proxy = false
 # ad_tag = "..."
+# disable_colors = false  # Disable colored output in logs (useful for files/systemd)
+
+[network]
+ipv4 = true
+ipv6 = true   # set false to disable, omit for auto
+prefer = 4    # 4 or 6
+multipath = false
 
 [general.modes]
 classic = false
@@ -240,7 +216,9 @@ ip = "::"
 
 # Users to show in the startup log (tg:// links)
 [general.links]
-show = ["hello"] # Users to show in the startup log (tg:// links)
+show = ["hello"]          # Only show links for user "hello"
+# show = ["alice", "bob"] # Only show links for alice and bob
+# show = "*"              # Show links for all users
 # public_host = "proxy.example.com"  # Host (IP or domain) for tg:// links
 # public_port = 443                  # Port for tg:// links (default: server.port)
 

ROADMAP.md

@@ -0,0 +1,34 @@
+### 3.0.0 Anschluss
+- **Middle Proxy now is stable**, confirmed on canary-deploy over ~20 users
+- Ad-tag now is working
+- DC=203/CDN now is working over ME
+- `getProxyConfig` and `ProxySecret` are automated
+- Version order is now in format `3.0.0` - without Windows-style "microfixes"
+
+### 3.0.1 Kabelsammler
+- Handshake timeouts fixed
+- Connectivity logging refactored
+- Docker: tmpfs for ProxyConfig and ProxySecret
+- Public Host and Port in config
+- ME Relays Head-of-Line Blocking fixed
+- ME Ping
+
+### 3.0.2 Microtrencher
+- New [network] section
+- ME Fixes
+- Small bugs coverage
+
+### 3.0.3 Ausrutscher
+- ME as stateful, no conn-id migration
+- No `flush()` on datapath after RpcWriter
+- Hightech parser for IPv6 without regexp
+- `nat_probe = true` by default
+- Timeout for `recv()` in STUN-client
+- ConnRegistry review
+- Dualstack emergency reconnect
+
+### 3.0.4 Schneeflecken
+- Only WARN and Links in Normal log
+- Consistent IP-family detection
+- Includes for config
+- `nonce_frame_hex` in log only with `DEBUG`

config.toml

@@ -1,9 +1,50 @@
 # === General Settings ===
 [general]
-prefer_ipv6 = true
+# prefer_ipv6 is deprecated; use [network].prefer instead
+prefer_ipv6 = false
 fast_mode = true
 use_middle_proxy = true
 #ad_tag = "00000000000000000000000000000000"
+# Path to proxy-secret binary (auto-downloaded if missing).
+proxy_secret_path = "proxy-secret"
+
+# === Middle Proxy (ME) ===
+# Public IP override for ME KDF when behind NAT; leave unset to auto-detect.
+#middle_proxy_nat_ip = "203.0.113.10"
+# Enable STUN probing to discover public IP:port for ME.
+middle_proxy_nat_probe = true
+# Primary STUN server (host:port); defaults to Telegram STUN when empty.
+middle_proxy_nat_stun = "stun.l.google.com:19302"
+# Optional fallback STUN servers list.
+middle_proxy_nat_stun_servers = ["stun1.l.google.com:19302", "stun2.l.google.com:19302"]
+# Desired number of concurrent ME writers in pool.
+middle_proxy_pool_size = 16
+# Pre-initialized warm-standby ME connections kept idle.
+middle_proxy_warm_standby = 8
+# Ignore STUN/interface mismatch and keep ME enabled even if IP differs.
+stun_iface_mismatch_ignore = false
+# Keepalive padding frames - fl==4
+me_keepalive_enabled = true
+me_keepalive_interval_secs = 25           # Period between keepalives
+me_keepalive_jitter_secs = 5              # Jitter added to interval
+me_keepalive_payload_random = true        # Randomize 4-byte payload (vs zeros)
+# Stagger extra ME connections on warmup to de-phase lifecycles.
+me_warmup_stagger_enabled = true
+me_warmup_step_delay_ms = 500             # Base delay between extra connects
+me_warmup_step_jitter_ms = 300            # Jitter for warmup delay
+# Reconnect policy knobs.
+me_reconnect_max_concurrent_per_dc = 1    # Parallel reconnects per DC - EXPERIMENTAL! UNSTABLE!
+me_reconnect_backoff_base_ms = 500        # Backoff start
+me_reconnect_backoff_cap_ms = 30000       # Backoff cap
+me_reconnect_fast_retry_count = 11        # Quick retries before backoff
+
+[network]
+# Enable/disable families; ipv6 = true/false/auto(None)
+ipv4 = true
+ipv6 = true
+# prefer = 4 or 6
+prefer = 4
+multipath = false
 
 # Log level: debug | verbose | normal | silent
 # Can be overridden with --silent or --log-level CLI flags
@@ -41,10 +82,13 @@ show = ["hello"] # Users to show in the startup log (tg:// links)
 
 # === Timeouts (in seconds) ===
 [timeouts]
-client_handshake = 15
+client_handshake = 30
 tg_connect = 10
 client_keepalive = 60
 client_ack = 300
+# Quick ME reconnects for single-address DCs (count and per-attempt timeout, ms).
+me_one_retry = 12
+me_one_timeout_ms = 1200
 
 # === Anti-Censorship & Masking ===
 [censorship]

src/cli.rs

@@ -189,11 +189,18 @@ r#"# Telemt MTProxy — auto-generated config
 show_link = ["{username}"]
 
 [general]
+# prefer_ipv6 is deprecated; use [network].prefer
 prefer_ipv6 = false
 fast_mode = true
 use_middle_proxy = false
 log_level = "normal"
 
+[network]
+ipv4 = true
+ipv6 = true
+prefer = 4
+multipath = false
+
 [general.modes]
 classic = false
 secure = false
@@ -297,4 +304,4 @@ fn print_links(username: &str, secret: &str, port: u16, domain: &str) {
     println!("The proxy will auto-detect and display the correct link on startup.");
     println!("Check: journalctl -u telemt.service | head -30");
     println!("===================");
-}
+}

src/config/defaults.rs

@@ -0,0 +1,133 @@
+use std::net::IpAddr;
+use std::collections::HashMap;
+use serde::Deserialize;
+
+// Helper defaults kept private to the config module.
+pub(crate) fn default_true() -> bool {
+    true
+}
+
+pub(crate) fn default_port() -> u16 {
+    443
+}
+
+pub(crate) fn default_tls_domain() -> String {
+    "www.google.com".to_string()
+}
+
+pub(crate) fn default_mask_port() -> u16 {
+    443
+}
+
+pub(crate) fn default_fake_cert_len() -> usize {
+    2048
+}
+
+pub(crate) fn default_replay_check_len() -> usize {
+    65_536
+}
+
+pub(crate) fn default_replay_window_secs() -> u64 {
+    1800
+}
+
+pub(crate) fn default_handshake_timeout() -> u64 {
+    15
+}
+
+pub(crate) fn default_connect_timeout() -> u64 {
+    10
+}
+
+pub(crate) fn default_keepalive() -> u64 {
+    60
+}
+
+pub(crate) fn default_ack_timeout() -> u64 {
+    300
+}
+pub(crate) fn default_me_one_retry() -> u8 {
+    3
+}
+
+pub(crate) fn default_me_one_timeout() -> u64 {
+    1500
+}
+
+pub(crate) fn default_listen_addr() -> String {
+    "0.0.0.0".to_string()
+}
+
+pub(crate) fn default_weight() -> u16 {
+    1
+}
+
+pub(crate) fn default_metrics_whitelist() -> Vec<IpAddr> {
+    vec!["127.0.0.1".parse().unwrap(), "::1".parse().unwrap()]
+}
+
+pub(crate) fn default_prefer_4() -> u8 {
+    4
+}
+
+pub(crate) fn default_unknown_dc_log_path() -> Option<String> {
+    Some("unknown-dc.txt".to_string())
+}
+
+pub(crate) fn default_pool_size() -> usize {
+    2
+}
+
+pub(crate) fn default_keepalive_interval() -> u64 {
+    25
+}
+
+pub(crate) fn default_keepalive_jitter() -> u64 {
+    5
+}
+
+pub(crate) fn default_warmup_step_delay_ms() -> u64 {
+    500
+}
+
+pub(crate) fn default_warmup_step_jitter_ms() -> u64 {
+    300
+}
+
+pub(crate) fn default_reconnect_backoff_base_ms() -> u64 {
+    500
+}
+
+pub(crate) fn default_reconnect_backoff_cap_ms() -> u64 {
+    30_000
+}
+
+// Custom deserializer helpers
+
+#[derive(Deserialize)]
+#[serde(untagged)]
+pub(crate) enum OneOrMany {
+    One(String),
+    Many(Vec<String>),
+}
+
+pub(crate) fn deserialize_dc_overrides<'de, D>(
+    deserializer: D,
+) -> std::result::Result<HashMap<String, Vec<String>>, D::Error>
+where
+    D: serde::de::Deserializer<'de>,
+{
+    let raw: HashMap<String, OneOrMany> = HashMap::deserialize(deserializer)?;
+    let mut out = HashMap::new();
+    for (dc, val) in raw {
+        let mut addrs = match val {
+            OneOrMany::One(s) => vec![s],
+            OneOrMany::Many(v) => v,
+        };
+        addrs.retain(|s| !s.trim().is_empty());
+        if !addrs.is_empty() {
+            out.insert(dc, addrs);
+        }
+    }
+    Ok(out)
+}

src/config/load.rs

@@ -0,0 +1,327 @@
+use std::collections::HashMap;
+use std::net::IpAddr;
+use std::path::Path;
+
+use rand::Rng;
+use tracing::warn;
+use serde::{Serialize, Deserialize};
+
+use crate::error::{ProxyError, Result};
+
+use super::defaults::*;
+use super::types::*;
+
+fn preprocess_includes(content: &str, base_dir: &Path, depth: u8) -> Result<String> {
+    if depth > 10 {
+        return Err(ProxyError::Config("Include depth > 10".into()));
+    }
+    let mut output = String::with_capacity(content.len());
+    for line in content.lines() {
+        let trimmed = line.trim();
+        if let Some(rest) = trimmed.strip_prefix("include") {
+            let rest = rest.trim();
+            if let Some(rest) = rest.strip_prefix('=') {
+                let path_str = rest.trim().trim_matches('"');
+                let resolved = base_dir.join(path_str);
+                let included = std::fs::read_to_string(&resolved)
+                    .map_err(|e| ProxyError::Config(e.to_string()))?;
+                let included_dir = resolved.parent().unwrap_or(base_dir);
+                output.push_str(&preprocess_includes(&included, included_dir, depth + 1)?);
+                output.push('\n');
+                continue;
+            }
+        }
+        output.push_str(line);
+        output.push('\n');
+    }
+    Ok(output)
+}
+
+fn validate_network_cfg(net: &mut NetworkConfig) -> Result<()> {
+    if !net.ipv4 && matches!(net.ipv6, Some(false)) {
+        return Err(ProxyError::Config(
+            "Both ipv4 and ipv6 are disabled in [network]".to_string(),
+        ));
+    }
+
+    if net.prefer != 4 && net.prefer != 6 {
+        return Err(ProxyError::Config(
+            "network.prefer must be 4 or 6".to_string(),
+        ));
+    }
+
+    if !net.ipv4 && net.prefer == 4 {
+        warn!("prefer=4 but ipv4=false; forcing prefer=6");
+        net.prefer = 6;
+    }
+
+    if matches!(net.ipv6, Some(false)) && net.prefer == 6 {
+        warn!("prefer=6 but ipv6=false; forcing prefer=4");
+        net.prefer = 4;
+    }
+
+    Ok(())
+}
+
+// ============= Main Config =============
+
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct ProxyConfig {
+    #[serde(default)]
+    pub general: GeneralConfig,
+
+    #[serde(default)]
+    pub network: NetworkConfig,
+
+    #[serde(default)]
+    pub server: ServerConfig,
+
+    #[serde(default)]
+    pub timeouts: TimeoutsConfig,
+
+    #[serde(default)]
+    pub censorship: AntiCensorshipConfig,
+
+    #[serde(default)]
+    pub access: AccessConfig,
+
+    #[serde(default)]
+    pub upstreams: Vec<UpstreamConfig>,
+
+    #[serde(default)]
+    pub show_link: ShowLink,
+
+    /// DC address overrides for non-standard DCs (CDN, media, test, etc.)
+    /// Keys are DC indices as strings, values are one or more "ip:port" addresses.
+    /// Matches the C implementation's `proxy_for <dc_id> <ip>:<port>` config directive.
+    /// Example in config.toml:
+    ///   [dc_overrides]
+    ///   "203" = ["149.154.175.100:443", "91.105.192.100:443"]
+    #[serde(default, deserialize_with = "deserialize_dc_overrides")]
+    pub dc_overrides: HashMap<String, Vec<String>>,
+
+    /// Default DC index (1-5) for unmapped non-standard DCs.
+    /// Matches the C implementation's `default <dc_id>` config directive.
+    /// If not set, defaults to 2 (matching Telegram's official `default 2;` in proxy-multi.conf).
+    #[serde(default)]
+    pub default_dc: Option<u8>,
+}
+
+impl ProxyConfig {
+    pub fn load<P: AsRef<Path>>(path: P) -> Result<Self> {
+        let content =
+            std::fs::read_to_string(&path).map_err(|e| ProxyError::Config(e.to_string()))?;
+        let base_dir = path.as_ref().parent().unwrap_or(Path::new("."));
+        let processed = preprocess_includes(&content, base_dir, 0)?;
+
+        let mut config: ProxyConfig =
+            toml::from_str(&processed).map_err(|e| ProxyError::Config(e.to_string()))?;
+
+        // Validate secrets.
+        for (user, secret) in &config.access.users {
+            if !secret.chars().all(|c| c.is_ascii_hexdigit()) || secret.len() != 32 {
+                return Err(ProxyError::InvalidSecret {
+                    user: user.clone(),
+                    reason: "Must be 32 hex characters".to_string(),
+                });
+            }
+        }
+
+        // Validate tls_domain.
+        if config.censorship.tls_domain.is_empty() {
+            return Err(ProxyError::Config("tls_domain cannot be empty".to_string()));
+        }
+
+        // Validate mask_unix_sock.
+        if let Some(ref sock_path) = config.censorship.mask_unix_sock {
+            if sock_path.is_empty() {
+                return Err(ProxyError::Config(
+                    "mask_unix_sock cannot be empty".to_string(),
+                ));
+            }
+            #[cfg(unix)]
+            if sock_path.len() > 107 {
+                return Err(ProxyError::Config(format!(
+                    "mask_unix_sock path too long: {} bytes (max 107)",
+                    sock_path.len()
+                )));
+            }
+            #[cfg(not(unix))]
+            return Err(ProxyError::Config(
+                "mask_unix_sock is only supported on Unix platforms".to_string(),
+            ));
+
+            if config.censorship.mask_host.is_some() {
+                return Err(ProxyError::Config(
+                    "mask_unix_sock and mask_host are mutually exclusive".to_string(),
+                ));
+            }
+        }
+
+        // Default mask_host to tls_domain if not set and no unix socket configured.
+        if config.censorship.mask_host.is_none() && config.censorship.mask_unix_sock.is_none() {
+            config.censorship.mask_host = Some(config.censorship.tls_domain.clone());
+        }
+
+        // Migration: prefer_ipv6 -> network.prefer.
+        if config.general.prefer_ipv6 {
+            if config.network.prefer == 4 {
+                config.network.prefer = 6;
+            }
+            warn!("prefer_ipv6 is deprecated, use [network].prefer = 6");
+        }
+
+        // Auto-enable NAT probe when Middle Proxy is requested.
+        if config.general.use_middle_proxy && !config.general.middle_proxy_nat_probe {
+            config.general.middle_proxy_nat_probe = true;
+            warn!("Auto-enabled middle_proxy_nat_probe for middle proxy mode");
+        }
+
+        validate_network_cfg(&mut config.network)?;
+
+        // Random fake_cert_len only when default is in use.
+        if config.censorship.fake_cert_len == default_fake_cert_len() {
+            config.censorship.fake_cert_len = rand::rng().gen_range(1024..4096);
+        }
+
+        // Resolve listen_tcp: explicit value wins, otherwise auto-detect.
+        // If unix socket is set → TCP only when listen_addr_ipv4 or listeners are explicitly provided.
+        // If no unix socket → TCP always (backward compat).
+        let listen_tcp = config.server.listen_tcp.unwrap_or_else(|| {
+            if config.server.listen_unix_sock.is_some() {
+                // Unix socket present: TCP only if user explicitly set addresses or listeners.
+                config.server.listen_addr_ipv4.is_some()
+                    || !config.server.listeners.is_empty()
+            } else {
+                true
+            }
+        });
+
+        // Migration: Populate listeners if empty (skip when listen_tcp = false).
+        if config.server.listeners.is_empty() && listen_tcp {
+            let ipv4_str = config.server.listen_addr_ipv4
+                .as_deref()
+                .unwrap_or("0.0.0.0");
+            if let Ok(ipv4) = ipv4_str.parse::<IpAddr>() {
+                config.server.listeners.push(ListenerConfig {
+                    ip: ipv4,
+                    announce: None,
+                    announce_ip: None,
+                });
+            }
+            if let Some(ipv6_str) = &config.server.listen_addr_ipv6 {
+                if let Ok(ipv6) = ipv6_str.parse::<IpAddr>() {
+                    config.server.listeners.push(ListenerConfig {
+                        ip: ipv6,
+                        announce: None,
+                        announce_ip: None,
+                    });
+                }
+            }
+        }
+
+        // Migration: announce_ip → announce for each listener.
+        for listener in &mut config.server.listeners {
+            if listener.announce.is_none() && listener.announce_ip.is_some() {
+                listener.announce = Some(listener.announce_ip.unwrap().to_string());
+            }
+        }
+
+        // Migration: show_link (top-level) → general.links.show.
+        if !config.show_link.is_empty() && config.general.links.show.is_empty() {
+            config.general.links.show = config.show_link.clone();
+        }
+
+        // Migration: Populate upstreams if empty (Default Direct).
+        if config.upstreams.is_empty() {
+            config.upstreams.push(UpstreamConfig {
+                upstream_type: UpstreamType::Direct { interface: None },
+                weight: 1,
+                enabled: true,
+                scopes: String::new(),
+                selected_scope: String::new(),
+            });
+        }
+
+        // Ensure default DC203 override is present.
+        config
+            .dc_overrides
+            .entry("203".to_string())
+            .or_insert_with(|| vec!["91.105.192.100:443".to_string()]);
+
+        Ok(config)
+    }
+
+    pub fn validate(&self) -> Result<()> {
+        if self.access.users.is_empty() {
+            return Err(ProxyError::Config("No users configured".to_string()));
+        }
+
+        if !self.general.modes.classic && !self.general.modes.secure && !self.general.modes.tls {
+            return Err(ProxyError::Config("No modes enabled".to_string()));
+        }
+
+        if self.censorship.tls_domain.contains(' ') || self.censorship.tls_domain.contains('/') {
+            return Err(ProxyError::Config(format!(
+                "Invalid tls_domain: '{}'. Must be a valid domain name",
+                self.censorship.tls_domain
+            )));
+        }
+
+        if let Some(tag) = &self.general.ad_tag {
+            let zeros = "00000000000000000000000000000000";
+            if tag == zeros {
+                warn!("ad_tag is all zeros; register a valid proxy tag via @MTProxybot to enable sponsored channel");
+            }
+            if tag.len() != 32 || tag.chars().any(|c| !c.is_ascii_hexdigit()) {
+                warn!("ad_tag is not a 32-char hex string; ensure you use value issued by @MTProxybot");
+            }
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn dc_overrides_allow_string_and_array() {
+        let toml = r#"
+            [dc_overrides]
+            "201" = "149.154.175.50:443"
+            "202" = ["149.154.167.51:443", "149.154.175.100:443"]
+        "#;
+        let cfg: ProxyConfig = toml::from_str(toml).unwrap();
+        assert_eq!(cfg.dc_overrides["201"], vec!["149.154.175.50:443"]);
+        assert_eq!(
+            cfg.dc_overrides["202"],
+            vec!["149.154.167.51:443", "149.154.175.100:443"]
+        );
+    }
+
+    #[test]
+    fn dc_overrides_inject_dc203_default() {
+        let toml = r#"
+            [general]
+            use_middle_proxy = false
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_dc_override_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let cfg = ProxyConfig::load(&path).unwrap();
+        assert!(cfg
+            .dc_overrides
+            .get("203")
+            .map(|v| v.contains(&"91.105.192.100:443".to_string()))
+            .unwrap_or(false));
+        let _ = std::fs::remove_file(path);
+    }
+}

src/config/mod.rs

@@ -1,798 +1,8 @@
-//! Configuration
+//! Configuration.
 
-use crate::error::{ProxyError, Result};
-use chrono::{DateTime, Utc};
-use serde::{Deserialize, Serialize};
-use serde::de::Deserializer;
-use std::collections::HashMap;
-use std::net::IpAddr;
-use std::path::Path;
-use tracing::warn;
+pub(crate) mod defaults;
+mod types;
+mod load;
 
-// ============= Helper Defaults =============
-
-fn default_true() -> bool {
-    true
-}
-fn default_port() -> u16 {
-    443
-}
-fn default_tls_domain() -> String {
-    "www.google.com".to_string()
-}
-fn default_mask_port() -> u16 {
-    443
-}
-fn default_replay_check_len() -> usize {
-    65536
-}
-fn default_replay_window_secs() -> u64 {
-    1800
-}
-fn default_handshake_timeout() -> u64 {
-    15
-}
-fn default_connect_timeout() -> u64 {
-    10
-}
-fn default_keepalive() -> u64 {
-    60
-}
-fn default_ack_timeout() -> u64 {
-    300
-}
-fn default_listen_addr() -> String {
-    "0.0.0.0".to_string()
-}
-fn default_fake_cert_len() -> usize {
-    2048
-}
-fn default_weight() -> u16 {
-    1
-}
-fn default_metrics_whitelist() -> Vec<IpAddr> {
-    vec!["127.0.0.1".parse().unwrap(), "::1".parse().unwrap()]
-}
-
-fn default_unknown_dc_log_path() -> Option<String> {
-    Some("unknown-dc.txt".to_string())
-}
-
-// ============= Custom Deserializers =============
-
-#[derive(Deserialize)]
-#[serde(untagged)]
-enum OneOrMany {
-    One(String),
-    Many(Vec<String>),
-}
-
-fn deserialize_dc_overrides<'de, D>(
-    deserializer: D,
-) -> std::result::Result<HashMap<String, Vec<String>>, D::Error>
-where
-    D: Deserializer<'de>,
-{
-    let raw: HashMap<String, OneOrMany> = HashMap::deserialize(deserializer)?;
-    let mut out = HashMap::new();
-    for (dc, val) in raw {
-        let mut addrs = match val {
-            OneOrMany::One(s) => vec![s],
-            OneOrMany::Many(v) => v,
-        };
-        addrs.retain(|s| !s.trim().is_empty());
-        if !addrs.is_empty() {
-            out.insert(dc, addrs);
-        }
-    }
-    Ok(out)
-}
-
-// ============= Log Level =============
-
-/// Logging verbosity level
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
-#[serde(rename_all = "lowercase")]
-pub enum LogLevel {
-    /// All messages including trace (trace + debug + info + warn + error)
-    Debug,
-    /// Detailed operational logs (debug + info + warn + error)
-    Verbose,
-    /// Standard operational logs (info + warn + error)
-    #[default]
-    Normal,
-    /// Minimal output: only warnings and errors (warn + error).
-    /// Startup messages (config, DC connectivity, proxy links) are always shown
-    /// via info! before the filter is applied.
-    Silent,
-}
-
-impl LogLevel {
-    /// Convert to tracing EnvFilter directive string
-    pub fn to_filter_str(&self) -> &'static str {
-        match self {
-            LogLevel::Debug => "trace",
-            LogLevel::Verbose => "debug",
-            LogLevel::Normal => "info",
-            LogLevel::Silent => "warn",
-        }
-    }
-
-    /// Parse from a loose string (CLI argument)
-    pub fn from_str_loose(s: &str) -> Self {
-        match s.to_lowercase().as_str() {
-            "debug" | "trace" => LogLevel::Debug,
-            "verbose" => LogLevel::Verbose,
-            "normal" | "info" => LogLevel::Normal,
-            "silent" | "quiet" | "error" | "warn" => LogLevel::Silent,
-            _ => LogLevel::Normal,
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn dc_overrides_allow_string_and_array() {
-        let toml = r#"
-            [dc_overrides]
-            "201" = "149.154.175.50:443"
-            "202" = ["149.154.167.51:443", "149.154.175.100:443"]
-        "#;
-        let cfg: ProxyConfig = toml::from_str(toml).unwrap();
-        assert_eq!(cfg.dc_overrides["201"], vec!["149.154.175.50:443"]);
-        assert_eq!(
-            cfg.dc_overrides["202"],
-            vec!["149.154.167.51:443", "149.154.175.100:443"]
-        );
-    }
-
-    #[test]
-    fn dc_overrides_inject_dc203_default() {
-        let toml = r#"
-            [general]
-            use_middle_proxy = false
-
-            [censorship]
-            tls_domain = "example.com"
-
-            [access.users]
-            user = "00000000000000000000000000000000"
-        "#;
-        let dir = std::env::temp_dir();
-        let path = dir.join("telemt_dc_override_test.toml");
-        std::fs::write(&path, toml).unwrap();
-        let cfg = ProxyConfig::load(&path).unwrap();
-        assert!(cfg
-            .dc_overrides
-            .get("203")
-            .map(|v| v.contains(&"91.105.192.100:443".to_string()))
-            .unwrap_or(false));
-        let _ = std::fs::remove_file(path);
-    }
-}
-
-impl std::fmt::Display for LogLevel {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            LogLevel::Debug => write!(f, "debug"),
-            LogLevel::Verbose => write!(f, "verbose"),
-            LogLevel::Normal => write!(f, "normal"),
-            LogLevel::Silent => write!(f, "silent"),
-        }
-    }
-}
-
-// ============= Sub-Configs =============
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct ProxyModes {
-    #[serde(default)]
-    pub classic: bool,
-    #[serde(default)]
-    pub secure: bool,
-    #[serde(default = "default_true")]
-    pub tls: bool,
-}
-
-impl Default for ProxyModes {
-    fn default() -> Self {
-        Self {
-            classic: true,
-            secure: true,
-            tls: true,
-        }
-    }
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct GeneralConfig {
-    #[serde(default)]
-    pub modes: ProxyModes,
-
-    #[serde(default)]
-    pub prefer_ipv6: bool,
-
-    #[serde(default = "default_true")]
-    pub fast_mode: bool,
-
-    #[serde(default)]
-    pub use_middle_proxy: bool,
-
-    #[serde(default)]
-    pub ad_tag: Option<String>,
-
-    /// Path to proxy-secret binary file (auto-downloaded if absent).
-    /// Infrastructure secret from https://core.telegram.org/getProxySecret
-    #[serde(default)]
-    pub proxy_secret_path: Option<String>,
-
-    /// Public IP override for middle-proxy NAT environments.
-    /// When set, this IP is used in ME key derivation and RPC_PROXY_REQ "our_addr".
-    #[serde(default)]
-    pub middle_proxy_nat_ip: Option<IpAddr>,
-
-    /// Enable STUN-based NAT probing to discover public IP:port for ME KDF.
-    #[serde(default)]
-    pub middle_proxy_nat_probe: bool,
-
-    /// Optional STUN server address (host:port) for NAT probing.
-    #[serde(default)]
-    pub middle_proxy_nat_stun: Option<String>,
-
-    /// Ignore STUN/interface IP mismatch (keep using Middle Proxy even if NAT detected).
-    #[serde(default)]
-    pub stun_iface_mismatch_ignore: bool,
-
-    /// Log unknown (non-standard) DC requests to a file (default: unknown-dc.txt). Set to null to disable.
-    #[serde(default = "default_unknown_dc_log_path")]
-    pub unknown_dc_log_path: Option<String>,
-
-    #[serde(default)]
-    pub log_level: LogLevel,
-
-    /// Disable colored output in logs (useful for files/systemd)
-    #[serde(default)]
-    pub disable_colors: bool,
-
-    /// [general.links] — proxy link generation overrides
-    #[serde(default)]
-    pub links: LinksConfig,
-}
-
-/// `[general.links]` — proxy link generation settings.
-#[derive(Debug, Clone, Serialize, Deserialize, Default)]
-pub struct LinksConfig {
-    /// List of usernames whose tg:// links to display at startup.
-    /// `"*"` = all users, `["alice", "bob"]` = specific users.
-    #[serde(default)]
-    pub show: ShowLink,
-
-    /// Public hostname/IP for tg:// link generation (overrides detected IP).
-    #[serde(default)]
-    pub public_host: Option<String>,
-
-    /// Public port for tg:// link generation (overrides server.port).
-    #[serde(default)]
-    pub public_port: Option<u16>,
-}
-
-impl Default for GeneralConfig {
-    fn default() -> Self {
-        Self {
-            modes: ProxyModes::default(),
-            prefer_ipv6: false,
-            fast_mode: true,
-            use_middle_proxy: false,
-            ad_tag: None,
-            proxy_secret_path: None,
-            middle_proxy_nat_ip: None,
-            middle_proxy_nat_probe: false,
-            middle_proxy_nat_stun: None,
-            stun_iface_mismatch_ignore: false,
-            unknown_dc_log_path: default_unknown_dc_log_path(),
-            log_level: LogLevel::Normal,
-            disable_colors: false,
-            links: LinksConfig::default(),
-        }
-    }
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct ServerConfig {
-    #[serde(default = "default_port")]
-    pub port: u16,
-
-    #[serde(default)]
-    pub listen_addr_ipv4: Option<String>,
-
-    #[serde(default)]
-    pub listen_addr_ipv6: Option<String>,
-
-    #[serde(default)]
-    pub listen_unix_sock: Option<String>,
-
-    /// Unix socket file permissions (octal, e.g. "0666" or "0777").
-    /// Applied via chmod after bind. Default: no change (inherits umask).
-    #[serde(default)]
-    pub listen_unix_sock_perm: Option<String>,
-
-    /// Enable TCP listening. Default: true when no unix socket, false when
-    /// listen_unix_sock is set. Set explicitly to override auto-detection.
-    #[serde(default)]
-    pub listen_tcp: Option<bool>,
-
-    #[serde(default)]
-    pub metrics_port: Option<u16>,
-
-    #[serde(default = "default_metrics_whitelist")]
-    pub metrics_whitelist: Vec<IpAddr>,
-
-    #[serde(default)]
-    pub listeners: Vec<ListenerConfig>,
-}
-
-impl Default for ServerConfig {
-    fn default() -> Self {
-        Self {
-            port: default_port(),
-            listen_addr_ipv4: Some(default_listen_addr()),
-            listen_addr_ipv6: Some("::".to_string()),
-            listen_unix_sock: None,
-            listen_unix_sock_perm: None,
-            listen_tcp: None,
-            metrics_port: None,
-            metrics_whitelist: default_metrics_whitelist(),
-            listeners: Vec::new(),
-        }
-    }
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct TimeoutsConfig {
-    #[serde(default = "default_handshake_timeout")]
-    pub client_handshake: u64,
-
-    #[serde(default = "default_connect_timeout")]
-    pub tg_connect: u64,
-
-    #[serde(default = "default_keepalive")]
-    pub client_keepalive: u64,
-
-    #[serde(default = "default_ack_timeout")]
-    pub client_ack: u64,
-}
-
-impl Default for TimeoutsConfig {
-    fn default() -> Self {
-        Self {
-            client_handshake: default_handshake_timeout(),
-            tg_connect: default_connect_timeout(),
-            client_keepalive: default_keepalive(),
-            client_ack: default_ack_timeout(),
-        }
-    }
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct AntiCensorshipConfig {
-    #[serde(default = "default_tls_domain")]
-    pub tls_domain: String,
-
-    #[serde(default = "default_true")]
-    pub mask: bool,
-
-    #[serde(default)]
-    pub mask_host: Option<String>,
-
-    #[serde(default = "default_mask_port")]
-    pub mask_port: u16,
-
-    #[serde(default)]
-    pub mask_unix_sock: Option<String>,
-
-    #[serde(default = "default_fake_cert_len")]
-    pub fake_cert_len: usize,
-}
-
-impl Default for AntiCensorshipConfig {
-    fn default() -> Self {
-        Self {
-            tls_domain: default_tls_domain(),
-            mask: true,
-            mask_host: None,
-            mask_port: default_mask_port(),
-            mask_unix_sock: None,
-            fake_cert_len: default_fake_cert_len(),
-        }
-    }
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct AccessConfig {
-    #[serde(default)]
-    pub users: HashMap<String, String>,
-
-    #[serde(default)]
-    pub user_max_tcp_conns: HashMap<String, usize>,
-
-    #[serde(default)]
-    pub user_expirations: HashMap<String, DateTime<Utc>>,
-
-    #[serde(default)]
-    pub user_data_quota: HashMap<String, u64>,
-
-    #[serde(default)]
-    pub user_max_unique_ips: HashMap<String, usize>,
-
-    #[serde(default = "default_replay_check_len")]
-    pub replay_check_len: usize,
-
-    #[serde(default = "default_replay_window_secs")]
-    pub replay_window_secs: u64,
-
-    #[serde(default)]
-    pub ignore_time_skew: bool,
-}
-
-impl Default for AccessConfig {
-    fn default() -> Self {
-        let mut users = HashMap::new();
-        users.insert(
-            "default".to_string(),
-            "00000000000000000000000000000000".to_string(),
-        );
-        Self {
-            users,
-            user_max_tcp_conns: HashMap::new(),
-            user_expirations: HashMap::new(),
-            user_data_quota: HashMap::new(),
-            user_max_unique_ips: HashMap::new(),
-            replay_check_len: default_replay_check_len(),
-            replay_window_secs: default_replay_window_secs(),
-            ignore_time_skew: false,
-        }
-    }
-}
-
-// ============= Aux Structures =============
-
-#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
-#[serde(tag = "type", rename_all = "lowercase")]
-pub enum UpstreamType {
-    Direct {
-        #[serde(default)]
-        interface: Option<String>,
-    },
-    Socks4 {
-        address: String,
-        #[serde(default)]
-        interface: Option<String>,
-        #[serde(default)]
-        user_id: Option<String>,
-    },
-    Socks5 {
-        address: String,
-        #[serde(default)]
-        interface: Option<String>,
-        #[serde(default)]
-        username: Option<String>,
-        #[serde(default)]
-        password: Option<String>,
-    },
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct UpstreamConfig {
-    #[serde(flatten)]
-    pub upstream_type: UpstreamType,
-    #[serde(default = "default_weight")]
-    pub weight: u16,
-    #[serde(default = "default_true")]
-    pub enabled: bool,
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct ListenerConfig {
-    pub ip: IpAddr,
-    /// IP address or hostname to announce in proxy links.
-    /// Takes precedence over `announce_ip` if both are set.
-    #[serde(default)]
-    pub announce: Option<String>,
-    /// Deprecated: Use `announce` instead. IP address to announce in proxy links.
-    /// Migrated to `announce` automatically if `announce` is not set.
-    #[serde(default)]
-    pub announce_ip: Option<IpAddr>,
-}
-
-// ============= ShowLink =============
-
-/// Controls which users' proxy links are displayed at startup.
-///
-/// In TOML, this can be:
-/// - `show_link = "*"`          — show links for all users
-/// - `show_link = ["a", "b"]`   — show links for specific users
-/// - omitted                    — show no links (default)
-#[derive(Debug, Clone)]
-pub enum ShowLink {
-    /// Don't show any links (default when omitted)
-    None,
-    /// Show links for all configured users
-    All,
-    /// Show links for specific users
-    Specific(Vec<String>),
-}
-
-impl Default for ShowLink {
-    fn default() -> Self {
-        ShowLink::None
-    }
-}
-
-impl ShowLink {
-    /// Returns true if no links should be shown
-    pub fn is_empty(&self) -> bool {
-        matches!(self, ShowLink::None) || matches!(self, ShowLink::Specific(v) if v.is_empty())
-    }
-
-    /// Resolve the list of user names to display, given all configured users
-    pub fn resolve_users<'a>(&'a self, all_users: &'a HashMap<String, String>) -> Vec<&'a String> {
-        match self {
-            ShowLink::None => vec![],
-            ShowLink::All => {
-                let mut names: Vec<&String> = all_users.keys().collect();
-                names.sort();
-                names
-            }
-            ShowLink::Specific(names) => names.iter().collect(),
-        }
-    }
-}
-
-impl Serialize for ShowLink {
-    fn serialize<S: serde::Serializer>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error> {
-        match self {
-            ShowLink::None => Vec::<String>::new().serialize(serializer),
-            ShowLink::All => serializer.serialize_str("*"),
-            ShowLink::Specific(v) => v.serialize(serializer),
-        }
-    }
-}
-
-impl<'de> Deserialize<'de> for ShowLink {
-    fn deserialize<D: serde::Deserializer<'de>>(deserializer: D) -> std::result::Result<Self, D::Error> {
-        use serde::de;
-
-        struct ShowLinkVisitor;
-
-        impl<'de> de::Visitor<'de> for ShowLinkVisitor {
-            type Value = ShowLink;
-
-            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
-                formatter.write_str(r#""*" or an array of user names"#)
-            }
-
-            fn visit_str<E: de::Error>(self, v: &str) -> std::result::Result<ShowLink, E> {
-                if v == "*" {
-                    Ok(ShowLink::All)
-                } else {
-                    Err(de::Error::invalid_value(
-                        de::Unexpected::Str(v),
-                        &r#""*""#,
-                    ))
-                }
-            }
-
-            fn visit_seq<A: de::SeqAccess<'de>>(self, mut seq: A) -> std::result::Result<ShowLink, A::Error> {
-                let mut names = Vec::new();
-                while let Some(name) = seq.next_element::<String>()? {
-                    names.push(name);
-                }
-                if names.is_empty() {
-                    Ok(ShowLink::None)
-                } else {
-                    Ok(ShowLink::Specific(names))
-                }
-            }
-        }
-
-        deserializer.deserialize_any(ShowLinkVisitor)
-    }
-}
-
-// ============= Main Config =============
-
-#[derive(Debug, Clone, Serialize, Deserialize, Default)]
-pub struct ProxyConfig {
-    #[serde(default)]
-    pub general: GeneralConfig,
-
-    #[serde(default)]
-    pub server: ServerConfig,
-
-    #[serde(default)]
-    pub timeouts: TimeoutsConfig,
-
-    #[serde(default)]
-    pub censorship: AntiCensorshipConfig,
-
-    #[serde(default)]
-    pub access: AccessConfig,
-
-    #[serde(default)]
-    pub upstreams: Vec<UpstreamConfig>,
-
-    #[serde(default)]
-    pub show_link: ShowLink,
-
-    /// DC address overrides for non-standard DCs (CDN, media, test, etc.)
-    /// Keys are DC indices as strings, values are one or more \"ip:port\" addresses.
-    /// Matches the C implementation's `proxy_for <dc_id> <ip>:<port>` config directive.
-    /// Example in config.toml:
-    ///   [dc_overrides]
-    ///   \"203\" = [\"149.154.175.100:443\", \"91.105.192.100:443\"]
-    #[serde(default, deserialize_with = "deserialize_dc_overrides")]
-    pub dc_overrides: HashMap<String, Vec<String>>,
-
-    /// Default DC index (1-5) for unmapped non-standard DCs.
-    /// Matches the C implementation's `default <dc_id>` config directive.
-    /// If not set, defaults to 2 (matching Telegram's official `default 2;` in proxy-multi.conf).
-    #[serde(default)]
-    pub default_dc: Option<u8>,
-}
-
-impl ProxyConfig {
-    pub fn load<P: AsRef<Path>>(path: P) -> Result<Self> {
-        let content =
-            std::fs::read_to_string(path).map_err(|e| ProxyError::Config(e.to_string()))?;
-
-        let mut config: ProxyConfig =
-            toml::from_str(&content).map_err(|e| ProxyError::Config(e.to_string()))?;
-
-        // Validate secrets
-        for (user, secret) in &config.access.users {
-            if !secret.chars().all(|c| c.is_ascii_hexdigit()) || secret.len() != 32 {
-                return Err(ProxyError::InvalidSecret {
-                    user: user.clone(),
-                    reason: "Must be 32 hex characters".to_string(),
-                });
-            }
-        }
-
-        // Validate tls_domain
-        if config.censorship.tls_domain.is_empty() {
-            return Err(ProxyError::Config("tls_domain cannot be empty".to_string()));
-        }
-
-        // Validate mask_unix_sock
-        if let Some(ref sock_path) = config.censorship.mask_unix_sock {
-            if sock_path.is_empty() {
-                return Err(ProxyError::Config(
-                    "mask_unix_sock cannot be empty".to_string(),
-                ));
-            }
-            #[cfg(unix)]
-            if sock_path.len() > 107 {
-                return Err(ProxyError::Config(format!(
-                    "mask_unix_sock path too long: {} bytes (max 107)",
-                    sock_path.len()
-                )));
-            }
-            #[cfg(not(unix))]
-            return Err(ProxyError::Config(
-                "mask_unix_sock is only supported on Unix platforms".to_string(),
-            ));
-
-            if config.censorship.mask_host.is_some() {
-                return Err(ProxyError::Config(
-                    "mask_unix_sock and mask_host are mutually exclusive".to_string(),
-                ));
-            }
-        }
-
-        // Default mask_host to tls_domain if not set and no unix socket configured
-        if config.censorship.mask_host.is_none() && config.censorship.mask_unix_sock.is_none() {
-            config.censorship.mask_host = Some(config.censorship.tls_domain.clone());
-        }
-
-        // Random fake_cert_len
-        use rand::Rng;
-        config.censorship.fake_cert_len = rand::rng().gen_range(1024..4096);
-
-        // Resolve listen_tcp: explicit value wins, otherwise auto-detect.
-        // If unix socket is set → TCP only when listen_addr_ipv4 or listeners are explicitly provided.
-        // If no unix socket → TCP always (backward compat).
-        let listen_tcp = config.server.listen_tcp.unwrap_or_else(|| {
-            if config.server.listen_unix_sock.is_some() {
-                // Unix socket present: TCP only if user explicitly set addresses or listeners
-                config.server.listen_addr_ipv4.is_some()
-                    || !config.server.listeners.is_empty()
-            } else {
-                true
-            }
-        });
-
-        // Migration: Populate listeners if empty (skip when listen_tcp = false)
-        if config.server.listeners.is_empty() && listen_tcp {
-            let ipv4_str = config.server.listen_addr_ipv4
-                .as_deref()
-                .unwrap_or("0.0.0.0");
-            if let Ok(ipv4) = ipv4_str.parse::<IpAddr>() {
-                config.server.listeners.push(ListenerConfig {
-                    ip: ipv4,
-                    announce: None,
-                    announce_ip: None,
-                });
-            }
-            if let Some(ipv6_str) = &config.server.listen_addr_ipv6 {
-                if let Ok(ipv6) = ipv6_str.parse::<IpAddr>() {
-                    config.server.listeners.push(ListenerConfig {
-                        ip: ipv6,
-                        announce: None,
-                        announce_ip: None,
-                    });
-                }
-            }
-        }
-
-        // Migration: announce_ip → announce for each listener
-        for listener in &mut config.server.listeners {
-            if listener.announce.is_none() && listener.announce_ip.is_some() {
-                listener.announce = Some(listener.announce_ip.unwrap().to_string());
-            }
-        }
-
-        // Migration: show_link (top-level) → general.links.show
-        if !config.show_link.is_empty() && config.general.links.show.is_empty() {
-            config.general.links.show = config.show_link.clone();
-        }
-
-        // Migration: Populate upstreams if empty (Default Direct)
-        if config.upstreams.is_empty() {
-            config.upstreams.push(UpstreamConfig {
-                upstream_type: UpstreamType::Direct { interface: None },
-                weight: 1,
-                enabled: true,
-            });
-        }
-
-        // Ensure default DC203 override is present.
-        config
-            .dc_overrides
-            .entry("203".to_string())
-            .or_insert_with(|| vec!["91.105.192.100:443".to_string()]);
-
-        Ok(config)
-    }
-
-    pub fn validate(&self) -> Result<()> {
-        if self.access.users.is_empty() {
-            return Err(ProxyError::Config("No users configured".to_string()));
-        }
-
-        if !self.general.modes.classic && !self.general.modes.secure && !self.general.modes.tls {
-            return Err(ProxyError::Config("No modes enabled".to_string()));
-        }
-
-        if self.censorship.tls_domain.contains(' ') || self.censorship.tls_domain.contains('/') {
-            return Err(ProxyError::Config(format!(
-                "Invalid tls_domain: '{}'. Must be a valid domain name",
-                self.censorship.tls_domain
-            )));
-        }
-
-        if let Some(tag) = &self.general.ad_tag {
-            let zeros = "00000000000000000000000000000000";
-            if tag == zeros {
-                warn!("ad_tag is all zeros; register a valid proxy tag via @MTProxybot to enable sponsored channel");
-            }
-            if tag.len() != 32 || tag.chars().any(|c| !c.is_ascii_hexdigit()) {
-                warn!("ad_tag is not a 32-char hex string; ensure you use value issued by @MTProxybot");
-            }
-        }
-
-        Ok(())
-    }
-}
+pub use load::ProxyConfig;
+pub use types::*;

src/config/types.rs

@@ -0,0 +1,588 @@
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+use std::net::IpAddr;
+
+use super::defaults::*;
+
+// ============= Log Level =============
+
+/// Logging verbosity level.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "lowercase")]
+pub enum LogLevel {
+    /// All messages including trace (trace + debug + info + warn + error).
+    Debug,
+    /// Detailed operational logs (debug + info + warn + error).
+    Verbose,
+    /// Standard operational logs (info + warn + error).
+    #[default]
+    Normal,
+    /// Minimal output: only warnings and errors (warn + error).
+    /// Startup messages (config, DC connectivity, proxy links) are always shown
+    /// via info! before the filter is applied.
+    Silent,
+}
+
+impl LogLevel {
+    /// Convert to tracing EnvFilter directive string.
+    pub fn to_filter_str(&self) -> &'static str {
+        match self {
+            LogLevel::Debug => "trace",
+            LogLevel::Verbose => "debug",
+            LogLevel::Normal => "info",
+            LogLevel::Silent => "warn",
+        }
+    }
+
+    /// Parse from a loose string (CLI argument).
+    pub fn from_str_loose(s: &str) -> Self {
+        match s.to_lowercase().as_str() {
+            "debug" | "trace" => LogLevel::Debug,
+            "verbose" => LogLevel::Verbose,
+            "normal" | "info" => LogLevel::Normal,
+            "silent" | "quiet" | "error" | "warn" => LogLevel::Silent,
+            _ => LogLevel::Normal,
+        }
+    }
+}
+
+impl std::fmt::Display for LogLevel {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            LogLevel::Debug => write!(f, "debug"),
+            LogLevel::Verbose => write!(f, "verbose"),
+            LogLevel::Normal => write!(f, "normal"),
+            LogLevel::Silent => write!(f, "silent"),
+        }
+    }
+}
+
+// ============= Sub-Configs =============
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ProxyModes {
+    #[serde(default)]
+    pub classic: bool,
+    #[serde(default)]
+    pub secure: bool,
+    #[serde(default = "default_true")]
+    pub tls: bool,
+}
+
+impl Default for ProxyModes {
+    fn default() -> Self {
+        Self {
+            classic: true,
+            secure: true,
+            tls: true,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct NetworkConfig {
+    #[serde(default = "default_true")]
+    pub ipv4: bool,
+
+    /// None = auto-detect IPv6 availability.
+    #[serde(default)]
+    pub ipv6: Option<bool>,
+
+    /// 4 or 6.
+    #[serde(default = "default_prefer_4")]
+    pub prefer: u8,
+
+    #[serde(default)]
+    pub multipath: bool,
+}
+
+impl Default for NetworkConfig {
+    fn default() -> Self {
+        Self {
+            ipv4: true,
+            ipv6: None,
+            prefer: 4,
+            multipath: false,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct GeneralConfig {
+    #[serde(default)]
+    pub modes: ProxyModes,
+
+    #[serde(default)]
+    pub prefer_ipv6: bool,
+
+    #[serde(default = "default_true")]
+    pub fast_mode: bool,
+
+    #[serde(default)]
+    pub use_middle_proxy: bool,
+
+    #[serde(default)]
+    pub ad_tag: Option<String>,
+
+    /// Path to proxy-secret binary file (auto-downloaded if absent).
+    /// Infrastructure secret from https://core.telegram.org/getProxySecret.
+    #[serde(default)]
+    pub proxy_secret_path: Option<String>,
+
+    /// Public IP override for middle-proxy NAT environments.
+    /// When set, this IP is used in ME key derivation and RPC_PROXY_REQ "our_addr".
+    #[serde(default)]
+    pub middle_proxy_nat_ip: Option<IpAddr>,
+
+    /// Enable STUN-based NAT probing to discover public IP:port for ME KDF.
+    #[serde(default)]
+    pub middle_proxy_nat_probe: bool,
+
+    /// Optional STUN server address (host:port) for NAT probing.
+    #[serde(default)]
+    pub middle_proxy_nat_stun: Option<String>,
+
+    /// Optional list of STUN servers for NAT probing fallback.
+    #[serde(default)]
+    pub middle_proxy_nat_stun_servers: Vec<String>,
+
+    /// Desired size of active Middle-Proxy writer pool.
+    #[serde(default = "default_pool_size")]
+    pub middle_proxy_pool_size: usize,
+
+    /// Number of warm standby ME connections kept pre-initialized.
+    #[serde(default)]
+    pub middle_proxy_warm_standby: usize,
+
+    /// Enable ME keepalive padding frames.
+    #[serde(default = "default_true")]
+    pub me_keepalive_enabled: bool,
+
+    /// Keepalive interval in seconds.
+    #[serde(default = "default_keepalive_interval")]
+    pub me_keepalive_interval_secs: u64,
+
+    /// Keepalive jitter in seconds.
+    #[serde(default = "default_keepalive_jitter")]
+    pub me_keepalive_jitter_secs: u64,
+
+    /// Keepalive payload randomized (4 bytes); otherwise zeros.
+    #[serde(default = "default_true")]
+    pub me_keepalive_payload_random: bool,
+
+    /// Enable staggered warmup of extra ME writers.
+    #[serde(default = "default_true")]
+    pub me_warmup_stagger_enabled: bool,
+
+    /// Base delay between warmup connections in ms.
+    #[serde(default = "default_warmup_step_delay_ms")]
+    pub me_warmup_step_delay_ms: u64,
+
+    /// Jitter for warmup delay in ms.
+    #[serde(default = "default_warmup_step_jitter_ms")]
+    pub me_warmup_step_jitter_ms: u64,
+
+    /// Max concurrent reconnect attempts per DC.
+    #[serde(default)]
+    pub me_reconnect_max_concurrent_per_dc: u32,
+
+    /// Base backoff in ms for reconnect.
+    #[serde(default = "default_reconnect_backoff_base_ms")]
+    pub me_reconnect_backoff_base_ms: u64,
+
+    /// Cap backoff in ms for reconnect.
+    #[serde(default = "default_reconnect_backoff_cap_ms")]
+    pub me_reconnect_backoff_cap_ms: u64,
+
+    /// Fast retry attempts before backoff.
+    #[serde(default)]
+    pub me_reconnect_fast_retry_count: u32,
+
+    /// Ignore STUN/interface IP mismatch (keep using Middle Proxy even if NAT detected).
+    #[serde(default)]
+    pub stun_iface_mismatch_ignore: bool,
+
+    /// Log unknown (non-standard) DC requests to a file (default: unknown-dc.txt). Set to null to disable.
+    #[serde(default = "default_unknown_dc_log_path")]
+    pub unknown_dc_log_path: Option<String>,
+
+    #[serde(default)]
+    pub log_level: LogLevel,
+
+    /// Disable colored output in logs (useful for files/systemd).
+    #[serde(default)]
+    pub disable_colors: bool,
+
+    /// [general.links] — proxy link generation overrides.
+    #[serde(default)]
+    pub links: LinksConfig,
+}
+
+impl Default for GeneralConfig {
+    fn default() -> Self {
+        Self {
+            modes: ProxyModes::default(),
+            prefer_ipv6: false,
+            fast_mode: true,
+            use_middle_proxy: false,
+            ad_tag: None,
+            proxy_secret_path: None,
+            middle_proxy_nat_ip: None,
+            middle_proxy_nat_probe: false,
+            middle_proxy_nat_stun: None,
+            middle_proxy_nat_stun_servers: Vec::new(),
+            middle_proxy_pool_size: default_pool_size(),
+            middle_proxy_warm_standby: 0,
+            me_keepalive_enabled: true,
+            me_keepalive_interval_secs: default_keepalive_interval(),
+            me_keepalive_jitter_secs: default_keepalive_jitter(),
+            me_keepalive_payload_random: true,
+            me_warmup_stagger_enabled: true,
+            me_warmup_step_delay_ms: default_warmup_step_delay_ms(),
+            me_warmup_step_jitter_ms: default_warmup_step_jitter_ms(),
+            me_reconnect_max_concurrent_per_dc: 1,
+            me_reconnect_backoff_base_ms: default_reconnect_backoff_base_ms(),
+            me_reconnect_backoff_cap_ms: default_reconnect_backoff_cap_ms(),
+            me_reconnect_fast_retry_count: 1,
+            stun_iface_mismatch_ignore: false,
+            unknown_dc_log_path: default_unknown_dc_log_path(),
+            log_level: LogLevel::Normal,
+            disable_colors: false,
+            links: LinksConfig::default(),
+        }
+    }
+}
+
+/// `[general.links]` — proxy link generation settings.
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct LinksConfig {
+    /// List of usernames whose tg:// links to display at startup.
+    /// `"*"` = all users, `["alice", "bob"]` = specific users.
+    #[serde(default)]
+    pub show: ShowLink,
+
+    /// Public hostname/IP for tg:// link generation (overrides detected IP).
+    #[serde(default)]
+    pub public_host: Option<String>,
+
+    /// Public port for tg:// link generation (overrides server.port).
+    #[serde(default)]
+    pub public_port: Option<u16>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ServerConfig {
+    #[serde(default = "default_port")]
+    pub port: u16,
+
+    #[serde(default)]
+    pub listen_addr_ipv4: Option<String>,
+
+    #[serde(default)]
+    pub listen_addr_ipv6: Option<String>,
+
+    #[serde(default)]
+    pub listen_unix_sock: Option<String>,
+
+    /// Unix socket file permissions (octal, e.g. "0666" or "0777").
+    /// Applied via chmod after bind. Default: no change (inherits umask).
+    #[serde(default)]
+    pub listen_unix_sock_perm: Option<String>,
+
+    /// Enable TCP listening. Default: true when no unix socket, false when
+    /// listen_unix_sock is set. Set explicitly to override auto-detection.
+    #[serde(default)]
+    pub listen_tcp: Option<bool>,
+
+    #[serde(default)]
+    pub metrics_port: Option<u16>,
+
+    #[serde(default = "default_metrics_whitelist")]
+    pub metrics_whitelist: Vec<IpAddr>,
+
+    #[serde(default)]
+    pub listeners: Vec<ListenerConfig>,
+}
+
+impl Default for ServerConfig {
+    fn default() -> Self {
+        Self {
+            port: default_port(),
+            listen_addr_ipv4: Some(default_listen_addr()),
+            listen_addr_ipv6: Some("::".to_string()),
+            listen_unix_sock: None,
+            listen_unix_sock_perm: None,
+            listen_tcp: None,
+            metrics_port: None,
+            metrics_whitelist: default_metrics_whitelist(),
+            listeners: Vec::new(),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct TimeoutsConfig {
+    #[serde(default = "default_handshake_timeout")]
+    pub client_handshake: u64,
+
+    #[serde(default = "default_connect_timeout")]
+    pub tg_connect: u64,
+
+    #[serde(default = "default_keepalive")]
+    pub client_keepalive: u64,
+
+    #[serde(default = "default_ack_timeout")]
+    pub client_ack: u64,
+
+    /// Number of quick ME reconnect attempts for single-address DC.
+    #[serde(default = "default_me_one_retry")]
+    pub me_one_retry: u8,
+
+    /// Timeout per quick attempt in milliseconds for single-address DC.
+    #[serde(default = "default_me_one_timeout")]
+    pub me_one_timeout_ms: u64,
+}
+
+impl Default for TimeoutsConfig {
+    fn default() -> Self {
+        Self {
+            client_handshake: default_handshake_timeout(),
+            tg_connect: default_connect_timeout(),
+            client_keepalive: default_keepalive(),
+            client_ack: default_ack_timeout(),
+            me_one_retry: default_me_one_retry(),
+            me_one_timeout_ms: default_me_one_timeout(),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AntiCensorshipConfig {
+    #[serde(default = "default_tls_domain")]
+    pub tls_domain: String,
+
+    #[serde(default = "default_true")]
+    pub mask: bool,
+
+    #[serde(default)]
+    pub mask_host: Option<String>,
+
+    #[serde(default = "default_mask_port")]
+    pub mask_port: u16,
+
+    #[serde(default)]
+    pub mask_unix_sock: Option<String>,
+
+    #[serde(default = "default_fake_cert_len")]
+    pub fake_cert_len: usize,
+}
+
+impl Default for AntiCensorshipConfig {
+    fn default() -> Self {
+        Self {
+            tls_domain: default_tls_domain(),
+            mask: true,
+            mask_host: None,
+            mask_port: default_mask_port(),
+            mask_unix_sock: None,
+            fake_cert_len: default_fake_cert_len(),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AccessConfig {
+    #[serde(default)]
+    pub users: HashMap<String, String>,
+
+    #[serde(default)]
+    pub user_max_tcp_conns: HashMap<String, usize>,
+
+    #[serde(default)]
+    pub user_expirations: HashMap<String, DateTime<Utc>>,
+
+    #[serde(default)]
+    pub user_data_quota: HashMap<String, u64>,
+
+    #[serde(default)]
+    pub user_max_unique_ips: HashMap<String, usize>,
+
+    #[serde(default = "default_replay_check_len")]
+    pub replay_check_len: usize,
+
+    #[serde(default = "default_replay_window_secs")]
+    pub replay_window_secs: u64,
+
+    #[serde(default)]
+    pub ignore_time_skew: bool,
+}
+
+impl Default for AccessConfig {
+    fn default() -> Self {
+        let mut users = HashMap::new();
+        users.insert(
+            "default".to_string(),
+            "00000000000000000000000000000000".to_string(),
+        );
+        Self {
+            users,
+            user_max_tcp_conns: HashMap::new(),
+            user_expirations: HashMap::new(),
+            user_data_quota: HashMap::new(),
+            user_max_unique_ips: HashMap::new(),
+            replay_check_len: default_replay_check_len(),
+            replay_window_secs: default_replay_window_secs(),
+            ignore_time_skew: false,
+        }
+    }
+}
+
+// ============= Aux Structures =============
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+#[serde(tag = "type", rename_all = "lowercase")]
+pub enum UpstreamType {
+    Direct {
+        #[serde(default)]
+        interface: Option<String>,
+    },
+    Socks4 {
+        address: String,
+        #[serde(default)]
+        interface: Option<String>,
+        #[serde(default)]
+        user_id: Option<String>,
+    },
+    Socks5 {
+        address: String,
+        #[serde(default)]
+        interface: Option<String>,
+        #[serde(default)]
+        username: Option<String>,
+        #[serde(default)]
+        password: Option<String>,
+    },
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct UpstreamConfig {
+    #[serde(flatten)]
+    pub upstream_type: UpstreamType,
+    #[serde(default = "default_weight")]
+    pub weight: u16,
+    #[serde(default = "default_true")]
+    pub enabled: bool,
+    #[serde(default)]
+    pub scopes: String,
+    #[serde(skip)]
+    pub selected_scope: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ListenerConfig {
+    pub ip: IpAddr,
+    /// IP address or hostname to announce in proxy links.
+    /// Takes precedence over `announce_ip` if both are set.
+    #[serde(default)]
+    pub announce: Option<String>,
+    /// Deprecated: Use `announce` instead. IP address to announce in proxy links.
+    /// Migrated to `announce` automatically if `announce` is not set.
+    #[serde(default)]
+    pub announce_ip: Option<IpAddr>,
+}
+
+// ============= ShowLink =============
+
+/// Controls which users' proxy links are displayed at startup.
+///
+/// In TOML, this can be:
+/// - `show_link = "*"`          — show links for all users
+/// - `show_link = ["a", "b"]`   — show links for specific users
+/// - omitted                    — show no links (default)
+#[derive(Debug, Clone)]
+pub enum ShowLink {
+    /// Don't show any links (default when omitted).
+    None,
+    /// Show links for all configured users.
+    All,
+    /// Show links for specific users.
+    Specific(Vec<String>),
+}
+
+impl Default for ShowLink {
+    fn default() -> Self {
+        ShowLink::None
+    }
+}
+
+impl ShowLink {
+    /// Returns true if no links should be shown.
+    pub fn is_empty(&self) -> bool {
+        matches!(self, ShowLink::None) || matches!(self, ShowLink::Specific(v) if v.is_empty())
+    }
+
+    /// Resolve the list of user names to display, given all configured users.
+    pub fn resolve_users<'a>(&'a self, all_users: &'a HashMap<String, String>) -> Vec<&'a String> {
+        match self {
+            ShowLink::None => vec![],
+            ShowLink::All => {
+                let mut names: Vec<&String> = all_users.keys().collect();
+                names.sort();
+                names
+            }
+            ShowLink::Specific(names) => names.iter().collect(),
+        }
+    }
+}
+
+impl Serialize for ShowLink {
+    fn serialize<S: serde::Serializer>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error> {
+        match self {
+            ShowLink::None => Vec::<String>::new().serialize(serializer),
+            ShowLink::All => serializer.serialize_str("*"),
+            ShowLink::Specific(v) => v.serialize(serializer),
+        }
+    }
+}
+
+impl<'de> Deserialize<'de> for ShowLink {
+    fn deserialize<D: serde::Deserializer<'de>>(deserializer: D) -> std::result::Result<Self, D::Error> {
+        use serde::de;
+
+        struct ShowLinkVisitor;
+
+        impl<'de> de::Visitor<'de> for ShowLinkVisitor {
+            type Value = ShowLink;
+
+            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                formatter.write_str(r#""*" or an array of user names"#)
+            }
+
+            fn visit_str<E: de::Error>(self, v: &str) -> std::result::Result<ShowLink, E> {
+                if v == "*" {
+                    Ok(ShowLink::All)
+                } else {
+                    Err(de::Error::invalid_value(
+                        de::Unexpected::Str(v),
+                        &r#""*""#,
+                    ))
+                }
+            }
+
+            fn visit_seq<A: de::SeqAccess<'de>>(self, mut seq: A) -> std::result::Result<ShowLink, A::Error> {
+                let mut names = Vec::new();
+                while let Some(name) = seq.next_element::<String>()? {
+                    names.push(name);
+                }
+                if names.is_empty() {
+                    Ok(ShowLink::None)
+                } else {
+                    Ok(ShowLink::Specific(names))
+                }
+            }
+        }
+
+        deserializer.deserialize_any(ShowLinkVisitor)
+    }
+}

src/crypto/random.rs

@@ -11,6 +11,9 @@ pub struct SecureRandom {
     inner: Mutex<SecureRandomInner>,
 }
 
+unsafe impl Send for SecureRandom {}
+unsafe impl Sync for SecureRandom {}
+
 struct SecureRandomInner {
     rng: StdRng,
     cipher: AesCtr,
@@ -211,4 +214,4 @@ mod tests {
         
         assert_ne!(shuffled, original);
     }
-}
+}

src/main.rs

@@ -16,6 +16,7 @@ mod config;
 mod crypto;
 mod error;
 mod ip_tracker;
+mod network;
 mod metrics;
 mod protocol;
 mod proxy;
@@ -27,16 +28,14 @@ mod util;
 use crate::config::{LogLevel, ProxyConfig};
 use crate::crypto::SecureRandom;
 use crate::ip_tracker::UserIpTracker;
+use crate::network::probe::{decide_network_capabilities, log_probe_result, run_probe};
 use crate::proxy::ClientHandler;
 use crate::stats::{ReplayChecker, Stats};
 use crate::stream::BufferPool;
 use crate::transport::middle_proxy::{
     MePool, fetch_proxy_config, run_me_ping, MePingFamily, MePingSample, format_sample_line,
-    stun_probe,
 };
 use crate::transport::{ListenOptions, UpstreamManager, create_listener};
-use crate::util::ip::detect_ip;
-use crate::protocol::constants::{TG_MIDDLE_PROXIES_V4, TG_MIDDLE_PROXIES_V6};
 
 fn parse_cli() -> (String, bool, Option<String>) {
     let mut config_path = "config.toml".to_string();
@@ -93,6 +92,10 @@ fn parse_cli() -> (String, bool, Option<String>) {
                 eprintln!("    --no-start             Don't start the service after install");
                 std::process::exit(0);
             }
+            "--version" | "-V" => {
+                println!("telemt {}", env!("CARGO_PKG_VERSION"));
+                std::process::exit(0);
+            }
             s if !s.starts_with('-') => {
                 config_path = s.to_string();
             }
@@ -107,18 +110,20 @@ fn parse_cli() -> (String, bool, Option<String>) {
 }
 
 fn print_proxy_links(host: &str, port: u16, config: &ProxyConfig) {
-    info!("--- Proxy Links ({}) ---", host);
+    info!(target: "telemt::links", "--- Proxy Links ({}) ---", host);
     for user_name in config.general.links.show.resolve_users(&config.access.users) {
         if let Some(secret) = config.access.users.get(user_name) {
-            info!("User: {}", user_name);
+            info!(target: "telemt::links", "User: {}", user_name);
             if config.general.modes.classic {
                 info!(
+                    target: "telemt::links",
                     "  Classic: tg://proxy?server={}&port={}&secret={}",
                     host, port, secret
                 );
             }
             if config.general.modes.secure {
                 info!(
+                    target: "telemt::links",
                     "  DD:      tg://proxy?server={}&port={}&secret=dd{}",
                     host, port, secret
                 );
@@ -126,22 +131,23 @@ fn print_proxy_links(host: &str, port: u16, config: &ProxyConfig) {
             if config.general.modes.tls {
                 let domain_hex = hex::encode(&config.censorship.tls_domain);
                 info!(
+                    target: "telemt::links",
                     "  EE-TLS:  tg://proxy?server={}&port={}&secret=ee{}{}",
                     host, port, secret, domain_hex
                 );
             }
         } else {
-            warn!("User '{}' in show_link not found", user_name);
+            warn!(target: "telemt::links", "User '{}' in show_link not found", user_name);
         }
     }
-    info!("------------------------");
+    info!(target: "telemt::links", "------------------------");
 }
 
 #[tokio::main]
 async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
     let (config_path, cli_silent, cli_log_level) = parse_cli();
 
-    let config = match ProxyConfig::load(&config_path) {
+    let mut config = match ProxyConfig::load(&config_path) {
         Ok(c) => c,
         Err(e) => {
             if std::path::Path::new(&config_path).exists() {
@@ -219,20 +225,20 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
         warn!("Using default tls_domain. Consider setting a custom domain.");
     }
 
-    let prefer_ipv6 = config.general.prefer_ipv6;
-    let mut use_middle_proxy = config.general.use_middle_proxy;
-    let config = Arc::new(config);
+    let probe = run_probe(
+        &config.network,
+        config.general.middle_proxy_nat_stun.clone(),
+        config.general.middle_proxy_nat_probe,
+    )
+    .await?;
+    let decision = decide_network_capabilities(&config.network, &probe);
+    log_probe_result(&probe, &decision);
+
+    let prefer_ipv6 = decision.prefer_ipv6();
+    let mut use_middle_proxy = config.general.use_middle_proxy && (decision.ipv4_me || decision.ipv6_me);
     let stats = Arc::new(Stats::new());
     let rng = Arc::new(SecureRandom::new());
 
-    let replay_checker = Arc::new(ReplayChecker::new(
-        config.access.replay_check_len,
-        Duration::from_secs(config.access.replay_window_secs),
-    ));
-
-    let upstream_manager = Arc::new(UpstreamManager::new(config.upstreams.clone()));
-    let buffer_pool = Arc::new(BufferPool::with_config(16 * 1024, 4096));
-
     // IP Tracker initialization
     let ip_tracker = Arc::new(UserIpTracker::new());
     ip_tracker.load_limits(&config.access.user_max_unique_ips).await;
@@ -244,39 +250,9 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
     // Connection concurrency limit
     let _max_connections = Arc::new(Semaphore::new(10_000));
 
-    // STUN check before choosing transport
-    if use_middle_proxy {
-        match stun_probe(config.general.middle_proxy_nat_stun.clone()).await {
-            Ok(Some(probe)) => {
-                info!(
-                    local_ip = %probe.local_addr.ip(),
-                    reflected_ip = %probe.reflected_addr.ip(),
-                    "STUN Autodetect:"
-                );
-                if probe.local_addr.ip() != probe.reflected_addr.ip()
-                    && !config.general.stun_iface_mismatch_ignore
-                {
-                    match crate::transport::middle_proxy::detect_public_ip().await {
-                        Some(ip) => {
-                            info!(
-                                local_ip = %probe.local_addr.ip(),
-                                reflected_ip = %probe.reflected_addr.ip(),
-                                public_ip = %ip,
-                                "STUN mismatch but public IP auto-detected, continuing with middle proxy"
-                            );
-                        }
-                        None => {
-                            warn!(
-                                "STUN/IP-on-Interface mismatch and public IP auto-detect failed -> fallback to direct-DC"
-                            );
-                            use_middle_proxy = false;
-                        }
-                    }
-                }
-            }
-            Ok(None) => warn!("STUN probe returned no address; continuing"),
-            Err(e) => warn!(error = %e, "STUN probe failed; continuing"),
-        }
+    if use_middle_proxy && !decision.ipv4_me && !decision.ipv6_me {
+        warn!("No usable IP family for Middle Proxy detected; falling back to direct DC");
+        use_middle_proxy = false;
     }
 
     // =====================================================================
@@ -348,21 +324,41 @@ match crate::transport::middle_proxy::fetch_proxy_secret(proxy_secret_path).awai
                     config.general.middle_proxy_nat_ip,
                     config.general.middle_proxy_nat_probe,
                     config.general.middle_proxy_nat_stun.clone(),
+                    config.general.middle_proxy_nat_stun_servers.clone(),
+                    probe.detected_ipv6,
+                    config.timeouts.me_one_retry,
+                    config.timeouts.me_one_timeout_ms,
                     cfg_v4.map.clone(),
                     cfg_v6.map.clone(),
                     cfg_v4.default_dc.or(cfg_v6.default_dc),
+                    decision.clone(),
+                    rng.clone(),
+                    stats.clone(),
+                    config.general.me_keepalive_enabled,
+                    config.general.me_keepalive_interval_secs,
+                    config.general.me_keepalive_jitter_secs,
+                    config.general.me_keepalive_payload_random,
+                    config.general.me_warmup_stagger_enabled,
+                    config.general.me_warmup_step_delay_ms,
+                    config.general.me_warmup_step_jitter_ms,
+                    config.general.me_reconnect_max_concurrent_per_dc,
+                    config.general.me_reconnect_backoff_base_ms,
+                    config.general.me_reconnect_backoff_cap_ms,
+                    config.general.me_reconnect_fast_retry_count,
                 );
 
-                match pool.init(2, &rng).await {
+                let pool_size = config.general.middle_proxy_pool_size.max(1);
+                match pool.init(pool_size, &rng).await {
                     Ok(()) => {
                         info!("Middle-End pool initialized successfully");
 
                         // Phase 4: Start health monitor
                         let pool_clone = pool.clone();
                         let rng_clone = rng.clone();
+                        let min_conns = pool_size;
                         tokio::spawn(async move {
                             crate::transport::middle_proxy::me_health_monitor(
-                                pool_clone, rng_clone, 2,
+                                pool_clone, rng_clone, min_conns,
                             )
                             .await;
                         });
@@ -408,12 +404,27 @@ match crate::transport::middle_proxy::fetch_proxy_secret(proxy_secret_path).awai
         None
     };
 
+    // If ME failed to initialize, force direct-only mode.
     if me_pool.is_some() {
         info!("Transport: Middle-End Proxy - all DC-over-RPC");
     } else {
+        use_middle_proxy = false;
+        // Make runtime config reflect direct-only mode for handlers.
+        config.general.use_middle_proxy = false;
         info!("Transport: Direct DC - TCP - standard DC-over-TCP");
     }
 
+    // Freeze config after possible fallback decision
+    let config = Arc::new(config);
+
+    let replay_checker = Arc::new(ReplayChecker::new(
+        config.access.replay_check_len,
+        Duration::from_secs(config.access.replay_window_secs),
+    ));
+
+    let upstream_manager = Arc::new(UpstreamManager::new(config.upstreams.clone()));
+    let buffer_pool = Arc::new(BufferPool::with_config(16 * 1024, 4096));
+
     // Middle-End ping before DC connectivity
     if let Some(ref pool) = me_pool {
         let me_results = run_me_ping(pool, &rng).await;
@@ -482,7 +493,12 @@ match crate::transport::middle_proxy::fetch_proxy_secret(proxy_secret_path).awai
     info!("================= Telegram DC Connectivity =================");
 
     let ping_results = upstream_manager
-        .ping_all_dcs(prefer_ipv6, &config.dc_overrides)
+        .ping_all_dcs(
+            prefer_ipv6,
+            &config.dc_overrides,
+            decision.ipv4_dc,
+            decision.ipv6_dc,
+        )
         .await;
 
 	for upstream_result in &ping_results {
@@ -559,8 +575,15 @@ match crate::transport::middle_proxy::fetch_proxy_secret(proxy_secret_path).awai
 
     // Background tasks
     let um_clone = upstream_manager.clone();
+    let decision_clone = decision.clone();
     tokio::spawn(async move {
-        um_clone.run_health_checks(prefer_ipv6).await;
+        um_clone
+            .run_health_checks(
+                prefer_ipv6,
+                decision_clone.ipv4_dc,
+                decision_clone.ipv6_dc,
+            )
+            .await;
     });
 
     let rc_clone = replay_checker.clone();
@@ -568,16 +591,31 @@ match crate::transport::middle_proxy::fetch_proxy_secret(proxy_secret_path).awai
         rc_clone.run_periodic_cleanup().await;
     });
 
-    let detected_ip = detect_ip().await;
+    let detected_ip_v4: Option<std::net::IpAddr> = probe
+        .reflected_ipv4
+        .map(|s| s.ip())
+        .or_else(|| probe.detected_ipv4.map(std::net::IpAddr::V4));
+    let detected_ip_v6: Option<std::net::IpAddr> = probe
+        .reflected_ipv6
+        .map(|s| s.ip())
+        .or_else(|| probe.detected_ipv6.map(std::net::IpAddr::V6));
     debug!(
         "Detected IPs: v4={:?} v6={:?}",
-        detected_ip.ipv4, detected_ip.ipv6
+        detected_ip_v4, detected_ip_v6
     );
 
     let mut listeners = Vec::new();
 
     for listener_conf in &config.server.listeners {
         let addr = SocketAddr::new(listener_conf.ip, config.server.port);
+        if addr.is_ipv4() && !decision.ipv4_dc {
+            warn!(%addr, "Skipping IPv4 listener: IPv4 disabled by [network]");
+            continue;
+        }
+        if addr.is_ipv6() && !decision.ipv6_dc {
+            warn!(%addr, "Skipping IPv6 listener: IPv6 disabled by [network]");
+            continue;
+        }
         let options = ListenOptions {
             ipv6_only: listener_conf.ip.is_ipv6(),
             ..Default::default()
@@ -594,11 +632,11 @@ match crate::transport::middle_proxy::fetch_proxy_secret(proxy_secret_path).awai
                 } else if listener_conf.ip.is_unspecified() {
                     // Auto-detect for unspecified addresses
                     if listener_conf.ip.is_ipv4() {
-                        detected_ip.ipv4
+                        detected_ip_v4
                             .map(|ip| ip.to_string())
                             .unwrap_or_else(|| listener_conf.ip.to_string())
                     } else {
-                        detected_ip.ipv6
+                        detected_ip_v6
                             .map(|ip| ip.to_string())
                             .unwrap_or_else(|| listener_conf.ip.to_string())
                     }
@@ -626,9 +664,8 @@ match crate::transport::middle_proxy::fetch_proxy_secret(proxy_secret_path).awai
         let (host, port) = if let Some(ref h) = config.general.links.public_host {
             (h.clone(), config.general.links.public_port.unwrap_or(config.server.port))
         } else {
-            let ip = detected_ip
-                .ipv4
-                .or(detected_ip.ipv6)
+            let ip = detected_ip_v4
+                .or(detected_ip_v6)
                 .map(|ip| ip.to_string());
             if ip.is_none() {
                 warn!("show_link is configured but public IP could not be detected. Set public_host in config.");
@@ -725,6 +762,8 @@ match crate::transport::middle_proxy::fetch_proxy_secret(proxy_secret_path).awai
     // Switch to user-configured log level after startup
     let runtime_filter = if has_rust_log {
         EnvFilter::from_default_env()
+    } else if matches!(effective_log_level, LogLevel::Silent) {
+        EnvFilter::new("warn,telemt::links=info")
     } else {
         EnvFilter::new(effective_log_level.to_filter_str())
     };

src/metrics.rs

@@ -91,6 +91,22 @@ fn render_metrics(stats: &Stats) -> String {
     let _ = writeln!(out, "# TYPE telemt_handshake_timeouts_total counter");
     let _ = writeln!(out, "telemt_handshake_timeouts_total {}", stats.get_handshake_timeouts());
 
+    let _ = writeln!(out, "# HELP telemt_me_keepalive_sent_total ME keepalive frames sent");
+    let _ = writeln!(out, "# TYPE telemt_me_keepalive_sent_total counter");
+    let _ = writeln!(out, "telemt_me_keepalive_sent_total {}", stats.get_me_keepalive_sent());
+
+    let _ = writeln!(out, "# HELP telemt_me_keepalive_failed_total ME keepalive send failures");
+    let _ = writeln!(out, "# TYPE telemt_me_keepalive_failed_total counter");
+    let _ = writeln!(out, "telemt_me_keepalive_failed_total {}", stats.get_me_keepalive_failed());
+
+    let _ = writeln!(out, "# HELP telemt_me_reconnect_attempts_total ME reconnect attempts");
+    let _ = writeln!(out, "# TYPE telemt_me_reconnect_attempts_total counter");
+    let _ = writeln!(out, "telemt_me_reconnect_attempts_total {}", stats.get_me_reconnect_attempts());
+
+    let _ = writeln!(out, "# HELP telemt_me_reconnect_success_total ME reconnect successes");
+    let _ = writeln!(out, "# TYPE telemt_me_reconnect_success_total counter");
+    let _ = writeln!(out, "telemt_me_reconnect_success_total {}", stats.get_me_reconnect_success());
+
     let _ = writeln!(out, "# HELP telemt_user_connections_total Per-user total connections");
     let _ = writeln!(out, "# TYPE telemt_user_connections_total counter");
     let _ = writeln!(out, "# HELP telemt_user_connections_current Per-user active connections");

src/network/mod.rs

@@ -0,0 +1,4 @@
+pub mod probe;
+pub mod stun;
+
+pub use stun::IpFamily;

src/network/probe.rs

@@ -0,0 +1,231 @@
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, UdpSocket};
+
+use tracing::{info, warn};
+
+use crate::config::NetworkConfig;
+use crate::error::Result;
+use crate::network::stun::{stun_probe_dual, DualStunResult, IpFamily};
+
+#[derive(Debug, Clone, Default)]
+pub struct NetworkProbe {
+    pub detected_ipv4: Option<Ipv4Addr>,
+    pub detected_ipv6: Option<Ipv6Addr>,
+    pub reflected_ipv4: Option<SocketAddr>,
+    pub reflected_ipv6: Option<SocketAddr>,
+    pub ipv4_is_bogon: bool,
+    pub ipv6_is_bogon: bool,
+    pub ipv4_nat_detected: bool,
+    pub ipv6_nat_detected: bool,
+    pub ipv4_usable: bool,
+    pub ipv6_usable: bool,
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct NetworkDecision {
+    pub ipv4_dc: bool,
+    pub ipv6_dc: bool,
+    pub ipv4_me: bool,
+    pub ipv6_me: bool,
+    pub effective_prefer: u8,
+    pub effective_multipath: bool,
+}
+
+impl NetworkDecision {
+    pub fn prefer_ipv6(&self) -> bool {
+        self.effective_prefer == 6
+    }
+
+    pub fn me_families(&self) -> Vec<IpFamily> {
+        let mut res = Vec::new();
+        if self.ipv4_me {
+            res.push(IpFamily::V4);
+        }
+        if self.ipv6_me {
+            res.push(IpFamily::V6);
+        }
+        res
+    }
+}
+
+pub async fn run_probe(config: &NetworkConfig, stun_addr: Option<String>, nat_probe: bool) -> Result<NetworkProbe> {
+    let mut probe = NetworkProbe::default();
+
+    probe.detected_ipv4 = detect_local_ip_v4();
+    probe.detected_ipv6 = detect_local_ip_v6();
+
+    probe.ipv4_is_bogon = probe.detected_ipv4.map(is_bogon_v4).unwrap_or(false);
+    probe.ipv6_is_bogon = probe.detected_ipv6.map(is_bogon_v6).unwrap_or(false);
+
+    let stun_server = stun_addr.unwrap_or_else(|| "stun.l.google.com:19302".to_string());
+    let stun_res = if nat_probe {
+        match stun_probe_dual(&stun_server).await {
+            Ok(res) => res,
+            Err(e) => {
+                warn!(error = %e, "STUN probe failed, continuing without reflection");
+                DualStunResult::default()
+            }
+        }
+    } else {
+        DualStunResult::default()
+    };
+    probe.reflected_ipv4 = stun_res.v4.map(|r| r.reflected_addr);
+    probe.reflected_ipv6 = stun_res.v6.map(|r| r.reflected_addr);
+
+    probe.ipv4_nat_detected = match (probe.detected_ipv4, probe.reflected_ipv4) {
+        (Some(det), Some(reflected)) => det != reflected.ip(),
+        _ => false,
+    };
+    probe.ipv6_nat_detected = match (probe.detected_ipv6, probe.reflected_ipv6) {
+        (Some(det), Some(reflected)) => det != reflected.ip(),
+        _ => false,
+    };
+
+    probe.ipv4_usable = config.ipv4
+        && probe.detected_ipv4.is_some()
+        && (!probe.ipv4_is_bogon || probe.reflected_ipv4.map(|r| !is_bogon(r.ip())).unwrap_or(false));
+
+    let ipv6_enabled = config.ipv6.unwrap_or(probe.detected_ipv6.is_some());
+    probe.ipv6_usable = ipv6_enabled
+        && probe.detected_ipv6.is_some()
+        && (!probe.ipv6_is_bogon || probe.reflected_ipv6.map(|r| !is_bogon(r.ip())).unwrap_or(false));
+
+    Ok(probe)
+}
+
+pub fn decide_network_capabilities(config: &NetworkConfig, probe: &NetworkProbe) -> NetworkDecision {
+    let mut decision = NetworkDecision::default();
+
+    decision.ipv4_dc = config.ipv4 && probe.detected_ipv4.is_some();
+    decision.ipv6_dc = config.ipv6.unwrap_or(probe.detected_ipv6.is_some()) && probe.detected_ipv6.is_some();
+
+    decision.ipv4_me = config.ipv4
+        && probe.detected_ipv4.is_some()
+        && (!probe.ipv4_is_bogon || probe.reflected_ipv4.is_some());
+
+    let ipv6_enabled = config.ipv6.unwrap_or(probe.detected_ipv6.is_some());
+    decision.ipv6_me = ipv6_enabled
+        && probe.detected_ipv6.is_some()
+        && (!probe.ipv6_is_bogon || probe.reflected_ipv6.is_some());
+
+    decision.effective_prefer = match config.prefer {
+        6 if decision.ipv6_me || decision.ipv6_dc => 6,
+        4 if decision.ipv4_me || decision.ipv4_dc => 4,
+        6 => {
+            warn!("prefer=6 requested but IPv6 unavailable; falling back to IPv4");
+            4
+        }
+        _ => 4,
+    };
+
+    let me_families = decision.ipv4_me as u8 + decision.ipv6_me as u8;
+    decision.effective_multipath = config.multipath && me_families >= 2;
+
+    decision
+}
+
+fn detect_local_ip_v4() -> Option<Ipv4Addr> {
+    let socket = UdpSocket::bind("0.0.0.0:0").ok()?;
+    socket.connect("8.8.8.8:80").ok()?;
+    match socket.local_addr().ok()?.ip() {
+        IpAddr::V4(v4) => Some(v4),
+        _ => None,
+    }
+}
+
+fn detect_local_ip_v6() -> Option<Ipv6Addr> {
+    let socket = UdpSocket::bind("[::]:0").ok()?;
+    socket.connect("[2001:4860:4860::8888]:80").ok()?;
+    match socket.local_addr().ok()?.ip() {
+        IpAddr::V6(v6) => Some(v6),
+        _ => None,
+    }
+}
+
+pub fn is_bogon(ip: IpAddr) -> bool {
+    match ip {
+        IpAddr::V4(v4) => is_bogon_v4(v4),
+        IpAddr::V6(v6) => is_bogon_v6(v6),
+    }
+}
+
+pub fn is_bogon_v4(ip: Ipv4Addr) -> bool {
+    let octets = ip.octets();
+    if ip.is_private() || ip.is_loopback() || ip.is_link_local() {
+        return true;
+    }
+    if octets[0] == 0 {
+        return true;
+    }
+    if octets[0] == 100 && (octets[1] & 0xC0) == 64 {
+        return true;
+    }
+    if octets[0] == 192 && octets[1] == 0 && octets[2] == 0 {
+        return true;
+    }
+    if octets[0] == 192 && octets[1] == 0 && octets[2] == 2 {
+        return true;
+    }
+    if octets[0] == 198 && (octets[1] & 0xFE) == 18 {
+        return true;
+    }
+    if octets[0] == 198 && octets[1] == 51 && octets[2] == 100 {
+        return true;
+    }
+    if octets[0] == 203 && octets[1] == 0 && octets[2] == 113 {
+        return true;
+    }
+    if ip.is_multicast() {
+        return true;
+    }
+    if octets[0] >= 240 {
+        return true;
+    }
+    if ip.is_broadcast() {
+        return true;
+    }
+    false
+}
+
+pub fn is_bogon_v6(ip: Ipv6Addr) -> bool {
+    if ip.is_unspecified() || ip.is_loopback() || ip.is_unique_local() {
+        return true;
+    }
+    let segs = ip.segments();
+    if (segs[0] & 0xFFC0) == 0xFE80 {
+        return true;
+    }
+    if segs[0..5] == [0, 0, 0, 0, 0] && segs[5] == 0xFFFF {
+        return true;
+    }
+    if segs[0] == 0x0100 && segs[1..4] == [0, 0, 0] {
+        return true;
+    }
+    if segs[0] == 0x2001 && segs[1] == 0x0db8 {
+        return true;
+    }
+    if segs[0] == 0x2002 {
+        return true;
+    }
+    if ip.is_multicast() {
+        return true;
+    }
+    false
+}
+
+pub fn log_probe_result(probe: &NetworkProbe, decision: &NetworkDecision) {
+    info!(
+        ipv4 = probe.detected_ipv4.as_ref().map(|v| v.to_string()).unwrap_or_else(|| "-".into()),
+        ipv6 = probe.detected_ipv6.as_ref().map(|v| v.to_string()).unwrap_or_else(|| "-".into()),
+        reflected_v4 = probe.reflected_ipv4.as_ref().map(|v| v.ip().to_string()).unwrap_or_else(|| "-".into()),
+        reflected_v6 = probe.reflected_ipv6.as_ref().map(|v| v.ip().to_string()).unwrap_or_else(|| "-".into()),
+        ipv4_bogon = probe.ipv4_is_bogon,
+        ipv6_bogon = probe.ipv6_is_bogon,
+        ipv4_me = decision.ipv4_me,
+        ipv6_me = decision.ipv6_me,
+        ipv4_dc = decision.ipv4_dc,
+        ipv6_dc = decision.ipv6_dc,
+        prefer = decision.effective_prefer,
+        multipath = decision.effective_multipath,
+        "Network capabilities resolved"
+    );
+}

src/network/stun.rs

@@ -0,0 +1,210 @@
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
+
+use tokio::net::{lookup_host, UdpSocket};
+use tokio::time::{timeout, Duration, sleep};
+
+use crate::error::{ProxyError, Result};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum IpFamily {
+    V4,
+    V6,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct StunProbeResult {
+    pub local_addr: SocketAddr,
+    pub reflected_addr: SocketAddr,
+    pub family: IpFamily,
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct DualStunResult {
+    pub v4: Option<StunProbeResult>,
+    pub v6: Option<StunProbeResult>,
+}
+
+pub async fn stun_probe_dual(stun_addr: &str) -> Result<DualStunResult> {
+    let (v4, v6) = tokio::join!(
+        stun_probe_family(stun_addr, IpFamily::V4),
+        stun_probe_family(stun_addr, IpFamily::V6),
+    );
+
+    Ok(DualStunResult {
+        v4: v4?,
+        v6: v6?,
+    })
+}
+
+pub async fn stun_probe_family(stun_addr: &str, family: IpFamily) -> Result<Option<StunProbeResult>> {
+    use rand::RngCore;
+
+    let bind_addr = match family {
+        IpFamily::V4 => "0.0.0.0:0",
+        IpFamily::V6 => "[::]:0",
+    };
+
+    let socket = UdpSocket::bind(bind_addr)
+        .await
+        .map_err(|e| ProxyError::Proxy(format!("STUN bind failed: {e}")))?;
+
+    let target_addr = resolve_stun_addr(stun_addr, family).await?;
+    if let Some(addr) = target_addr {
+        match socket.connect(addr).await {
+            Ok(()) => {}
+            Err(e) if family == IpFamily::V6 && matches!(
+                e.kind(),
+                std::io::ErrorKind::NetworkUnreachable
+                | std::io::ErrorKind::HostUnreachable
+                | std::io::ErrorKind::Unsupported
+                | std::io::ErrorKind::NetworkDown
+            ) => return Ok(None),
+            Err(e) => return Err(ProxyError::Proxy(format!("STUN connect failed: {e}"))),
+        }
+    } else {
+        return Ok(None);
+    }
+
+    let mut req = [0u8; 20];
+    req[0..2].copy_from_slice(&0x0001u16.to_be_bytes()); // Binding Request
+    req[2..4].copy_from_slice(&0u16.to_be_bytes()); // length
+    req[4..8].copy_from_slice(&0x2112A442u32.to_be_bytes()); // magic cookie
+    rand::rng().fill_bytes(&mut req[8..20]); // transaction ID
+
+    let mut buf = [0u8; 256];
+    let mut attempt = 0;
+    let mut backoff = Duration::from_secs(1);
+    loop {
+        socket
+            .send(&req)
+            .await
+            .map_err(|e| ProxyError::Proxy(format!("STUN send failed: {e}")))?;
+
+        let recv_res = timeout(Duration::from_secs(3), socket.recv(&mut buf)).await;
+        let n = match recv_res {
+            Ok(Ok(n)) => n,
+            Ok(Err(e)) => return Err(ProxyError::Proxy(format!("STUN recv failed: {e}"))),
+            Err(_) => {
+                attempt += 1;
+                if attempt >= 3 {
+                    return Ok(None);
+                }
+                sleep(backoff).await;
+                backoff *= 2;
+                continue;
+            }
+        };
+
+        if n < 20 {
+            return Ok(None);
+        }
+
+        let magic = 0x2112A442u32.to_be_bytes();
+        let txid = &req[8..20];
+    let mut idx = 20;
+    while idx + 4 <= n {
+        let atype = u16::from_be_bytes(buf[idx..idx + 2].try_into().unwrap());
+        let alen = u16::from_be_bytes(buf[idx + 2..idx + 4].try_into().unwrap()) as usize;
+        idx += 4;
+        if idx + alen > n {
+            break;
+        }
+
+        match atype {
+            0x0020 /* XOR-MAPPED-ADDRESS */ | 0x0001 /* MAPPED-ADDRESS */ => {
+                if alen < 8 {
+                    break;
+                }
+                let family_byte = buf[idx + 1];
+                let port_bytes = [buf[idx + 2], buf[idx + 3]];
+                let len_check = match family_byte {
+                    0x01 => 4,
+                    0x02 => 16,
+                    _ => 0,
+                };
+                if len_check == 0 || alen < 4 + len_check {
+                    break;
+                }
+
+                let raw_ip = &buf[idx + 4..idx + 4 + len_check];
+                let mut port = u16::from_be_bytes(port_bytes);
+
+                let reflected_ip = if atype == 0x0020 {
+                    port ^= ((magic[0] as u16) << 8) | magic[1] as u16;
+                    match family_byte {
+                        0x01 => {
+                            let ip = [
+                                raw_ip[0] ^ magic[0],
+                                raw_ip[1] ^ magic[1],
+                                raw_ip[2] ^ magic[2],
+                                raw_ip[3] ^ magic[3],
+                            ];
+                            IpAddr::V4(Ipv4Addr::new(ip[0], ip[1], ip[2], ip[3]))
+                        }
+                        0x02 => {
+                            let mut ip = [0u8; 16];
+                            let xor_key = [magic.as_slice(), txid].concat();
+                            for (i, b) in raw_ip.iter().enumerate().take(16) {
+                                ip[i] = *b ^ xor_key[i];
+                            }
+                            IpAddr::V6(Ipv6Addr::from(ip))
+                        }
+                        _ => {
+                            idx += (alen + 3) & !3;
+                            continue;
+                        }
+                    }
+                } else {
+                    match family_byte {
+                        0x01 => IpAddr::V4(Ipv4Addr::new(raw_ip[0], raw_ip[1], raw_ip[2], raw_ip[3])),
+                        0x02 => IpAddr::V6(Ipv6Addr::from(<[u8; 16]>::try_from(raw_ip).unwrap())),
+                        _ => {
+                            idx += (alen + 3) & !3;
+                            continue;
+                        }
+                    }
+                };
+
+                let reflected_addr = SocketAddr::new(reflected_ip, port);
+                let local_addr = socket
+                    .local_addr()
+                    .map_err(|e| ProxyError::Proxy(format!("STUN local_addr failed: {e}")))?;
+
+                return Ok(Some(StunProbeResult {
+                    local_addr,
+                    reflected_addr,
+                    family,
+                }));
+            }
+            _ => {}
+        }
+
+        idx += (alen + 3) & !3;
+    }
+
+    }
+
+    Ok(None)
+}
+
+async fn resolve_stun_addr(stun_addr: &str, family: IpFamily) -> Result<Option<SocketAddr>> {
+    if let Ok(addr) = stun_addr.parse::<SocketAddr>() {
+        return Ok(match (addr.is_ipv4(), family) {
+            (true, IpFamily::V4) | (false, IpFamily::V6) => Some(addr),
+            _ => None,
+        });
+    }
+
+    let addrs = lookup_host(stun_addr)
+        .await
+        .map_err(|e| ProxyError::Proxy(format!("STUN resolve failed: {e}")))?;
+
+    let target = addrs
+        .filter(|a| match (a.is_ipv4(), family) {
+            (true, IpFamily::V4) => true,
+            (false, IpFamily::V6) => true,
+            _ => false,
+        })
+        .next();
+    Ok(target)
+}

src/proxy/direct_relay.rs

@@ -45,7 +45,7 @@ where
     );
 
     let tg_stream = upstream_manager
-        .connect(dc_addr, Some(success.dc_idx))
+        .connect(dc_addr, Some(success.dc_idx), user.strip_prefix("scope_").filter(|s| !s.is_empty()))
         .await?;
 
     debug!(peer = %success.peer, dc_addr = %dc_addr, "Connected, performing TG handshake");
@@ -80,7 +80,8 @@ where
 }
 
 fn get_dc_addr_static(dc_idx: i16, config: &ProxyConfig) -> Result<SocketAddr> {
-    let datacenters = if config.general.prefer_ipv6 {
+    let prefer_v6 = config.network.prefer == 6 && config.network.ipv6.unwrap_or(true);
+    let datacenters = if prefer_v6 {
         &*TG_DATACENTERS_V6
     } else {
         &*TG_DATACENTERS_V4
@@ -90,7 +91,6 @@ fn get_dc_addr_static(dc_idx: i16, config: &ProxyConfig) -> Result<SocketAddr> {
 
     let dc_key = dc_idx.to_string();
     if let Some(addrs) = config.dc_overrides.get(&dc_key) {
-        let prefer_v6 = config.general.prefer_ipv6;
         let mut parsed = Vec::new();
         for addr_str in addrs {
             match addr_str.parse::<SocketAddr>() {

src/stats/mod.rs

@@ -19,6 +19,10 @@ pub struct Stats {
     connects_all: AtomicU64,
     connects_bad: AtomicU64,
     handshake_timeouts: AtomicU64,
+    me_keepalive_sent: AtomicU64,
+    me_keepalive_failed: AtomicU64,
+    me_reconnect_attempts: AtomicU64,
+    me_reconnect_success: AtomicU64,
     user_stats: DashMap<String, UserStats>,
     start_time: parking_lot::RwLock<Option<Instant>>,
 }
@@ -43,8 +47,16 @@ impl Stats {
     pub fn increment_connects_all(&self) { self.connects_all.fetch_add(1, Ordering::Relaxed); }
     pub fn increment_connects_bad(&self) { self.connects_bad.fetch_add(1, Ordering::Relaxed); }
     pub fn increment_handshake_timeouts(&self) { self.handshake_timeouts.fetch_add(1, Ordering::Relaxed); }
+    pub fn increment_me_keepalive_sent(&self) { self.me_keepalive_sent.fetch_add(1, Ordering::Relaxed); }
+    pub fn increment_me_keepalive_failed(&self) { self.me_keepalive_failed.fetch_add(1, Ordering::Relaxed); }
+    pub fn increment_me_reconnect_attempt(&self) { self.me_reconnect_attempts.fetch_add(1, Ordering::Relaxed); }
+    pub fn increment_me_reconnect_success(&self) { self.me_reconnect_success.fetch_add(1, Ordering::Relaxed); }
     pub fn get_connects_all(&self) -> u64 { self.connects_all.load(Ordering::Relaxed) }
     pub fn get_connects_bad(&self) -> u64 { self.connects_bad.load(Ordering::Relaxed) }
+    pub fn get_me_keepalive_sent(&self) -> u64 { self.me_keepalive_sent.load(Ordering::Relaxed) }
+    pub fn get_me_keepalive_failed(&self) -> u64 { self.me_keepalive_failed.load(Ordering::Relaxed) }
+    pub fn get_me_reconnect_attempts(&self) -> u64 { self.me_reconnect_attempts.load(Ordering::Relaxed) }
+    pub fn get_me_reconnect_success(&self) -> u64 { self.me_reconnect_success.load(Ordering::Relaxed) }
     
     pub fn increment_user_connects(&self, user: &str) {
         self.user_stats.entry(user.to_string()).or_default()

src/transport/middle_proxy/codec.rs

@@ -4,6 +4,14 @@ use crate::crypto::{AesCbc, crc32};
 use crate::error::{ProxyError, Result};
 use crate::protocol::constants::*;
 
+/// Commands sent to dedicated writer tasks to avoid mutex contention on TCP writes.
+pub(crate) enum WriterCommand {
+    Data(Vec<u8>),
+    DataAndFlush(Vec<u8>),
+    Keepalive,
+    Close,
+}
+
 pub(crate) fn build_rpc_frame(seq_no: i32, payload: &[u8]) -> Vec<u8> {
     let total_len = (4 + 4 + payload.len() + 4) as u32;
     let mut frame = Vec::with_capacity(total_len as usize);
@@ -174,7 +182,19 @@ impl RpcWriter {
         if buf.len() >= 16 {
             self.iv.copy_from_slice(&buf[buf.len() - 16..]);
         }
-        self.writer.write_all(&buf).await.map_err(ProxyError::Io)?;
+        self.writer.write_all(&buf).await.map_err(ProxyError::Io)
+    }
+
+    pub(crate) async fn send_and_flush(&mut self, payload: &[u8]) -> Result<()> {
+        self.send(payload).await?;
         self.writer.flush().await.map_err(ProxyError::Io)
     }
+
+    pub(crate) async fn send_keepalive(&mut self, payload: [u8; 4]) -> Result<()> {
+        // Keepalive is a frame with fl == 4 and 4 bytes payload.
+        let mut frame = Vec::with_capacity(8);
+        frame.extend_from_slice(&4u32.to_le_bytes());
+        frame.extend_from_slice(&payload);
+        self.send(&frame).await
+    }
 }

src/transport/middle_proxy/config_updater.rs

@@ -3,7 +3,6 @@ use std::net::IpAddr;
 use std::sync::Arc;
 use std::time::Duration;
 
-use regex::Regex;
 use httpdate;
 use tracing::{debug, info, warn};
 
@@ -14,12 +13,69 @@ use super::secret::download_proxy_secret;
 use crate::crypto::SecureRandom;
 use std::time::SystemTime;
 
+async fn retry_fetch(url: &str) -> Option<ProxyConfigData> {
+    let delays = [1u64, 5, 15];
+    for (i, d) in delays.iter().enumerate() {
+        match fetch_proxy_config(url).await {
+            Ok(cfg) => return Some(cfg),
+            Err(e) => {
+                if i == delays.len() - 1 {
+                    warn!(error = %e, url, "fetch_proxy_config failed");
+                } else {
+                    debug!(error = %e, url, "fetch_proxy_config retrying");
+                    tokio::time::sleep(Duration::from_secs(*d)).await;
+                }
+            }
+        }
+    }
+    None
+}
+
 #[derive(Debug, Clone, Default)]
 pub struct ProxyConfigData {
     pub map: HashMap<i32, Vec<(IpAddr, u16)>>,
     pub default_dc: Option<i32>,
 }
 
+fn parse_host_port(s: &str) -> Option<(IpAddr, u16)> {
+    if let Some(bracket_end) = s.rfind(']') {
+        if s.starts_with('[') && bracket_end + 1 < s.len() && s.as_bytes().get(bracket_end + 1) == Some(&b':') {
+            let host = &s[1..bracket_end];
+            let port_str = &s[bracket_end + 2..];
+            let ip = host.parse::<IpAddr>().ok()?;
+            let port = port_str.parse::<u16>().ok()?;
+            return Some((ip, port));
+        }
+    }
+
+    let idx = s.rfind(':')?;
+    let host = &s[..idx];
+    let port_str = &s[idx + 1..];
+    let ip = host.parse::<IpAddr>().ok()?;
+    let port = port_str.parse::<u16>().ok()?;
+    Some((ip, port))
+}
+
+fn parse_proxy_line(line: &str) -> Option<(i32, IpAddr, u16)> {
+    // Accepts lines like:
+    // proxy_for 4 91.108.4.195:8888;
+    // proxy_for 2 [2001:67c:04e8:f002::d]:80;
+    // proxy_for 2 2001:67c:04e8:f002::d:80;
+    let trimmed = line.trim();
+    if !trimmed.starts_with("proxy_for") {
+        return None;
+    }
+    // Capture everything between dc and trailing ';'
+    let without_prefix = trimmed.trim_start_matches("proxy_for").trim();
+    let mut parts = without_prefix.split_whitespace();
+    let dc_str = parts.next()?;
+    let rest = parts.next()?;
+    let host_port = rest.trim_end_matches(';');
+    let dc = dc_str.parse::<i32>().ok()?;
+    let (ip, port) = parse_host_port(host_port)?;
+    Some((dc, ip, port))
+}
+
 pub async fn fetch_proxy_config(url: &str) -> Result<ProxyConfigData> {
     let resp = reqwest::get(url)
         .await
@@ -48,26 +104,26 @@ pub async fn fetch_proxy_config(url: &str) -> Result<ProxyConfigData> {
         .await
         .map_err(|e| crate::error::ProxyError::Proxy(format!("fetch_proxy_config read failed: {e}")))?;
 
-    let re_proxy = Regex::new(r"proxy_for\s+(-?\d+)\s+([^\s:]+):(\d+)\s*;").unwrap();
-    let re_default = Regex::new(r"default\s+(-?\d+)\s*;").unwrap();
-
     let mut map: HashMap<i32, Vec<(IpAddr, u16)>> = HashMap::new();
-    for cap in re_proxy.captures_iter(&text) {
-        if let (Some(dc), Some(host), Some(port)) = (cap.get(1), cap.get(2), cap.get(3)) {
-            if let Ok(dc_idx) = dc.as_str().parse::<i32>() {
-                if let Ok(ip) = host.as_str().parse::<IpAddr>() {
-                    if let Ok(port_num) = port.as_str().parse::<u16>() {
-                        map.entry(dc_idx).or_default().push((ip, port_num));
-                    }
-                }
-            }
+    for line in text.lines() {
+        if let Some((dc, ip, port)) = parse_proxy_line(line) {
+            map.entry(dc).or_default().push((ip, port));
         }
     }
 
-    let default_dc = re_default
-        .captures(&text)
-        .and_then(|c| c.get(1))
-        .and_then(|m| m.as_str().parse::<i32>().ok());
+    let default_dc = text
+        .lines()
+        .find_map(|l| {
+            let t = l.trim();
+            if let Some(rest) = t.strip_prefix("default") {
+                return rest
+                    .trim()
+                    .trim_end_matches(';')
+                    .parse::<i32>()
+                    .ok();
+            }
+            None
+        });
 
     Ok(ProxyConfigData { map, default_dc })
 }
@@ -80,7 +136,8 @@ pub async fn me_config_updater(pool: Arc<MePool>, rng: Arc<SecureRandom>, interv
         tick.tick().await;
 
         // Update proxy config v4
-        if let Ok(cfg) = fetch_proxy_config("https://core.telegram.org/getProxyConfig").await {
+        let cfg_v4 = retry_fetch("https://core.telegram.org/getProxyConfig").await;
+        if let Some(cfg) = cfg_v4 {
             let changed = pool.update_proxy_maps(cfg.map.clone(), None).await;
             if let Some(dc) = cfg.default_dc {
                 pool.default_dc.store(dc, std::sync::atomic::Ordering::Relaxed);
@@ -91,14 +148,20 @@ pub async fn me_config_updater(pool: Arc<MePool>, rng: Arc<SecureRandom>, interv
             } else {
                 debug!("ME config v4 unchanged");
             }
-        } else {
-            warn!("getProxyConfig update failed");
         }
 
         // Update proxy config v6 (optional)
-        if let Ok(cfg_v6) = fetch_proxy_config("https://core.telegram.org/getProxyConfigV6").await {
-            let _ = pool.update_proxy_maps(HashMap::new(), Some(cfg_v6.map)).await;
+        let cfg_v6 = retry_fetch("https://core.telegram.org/getProxyConfigV6").await;
+        if let Some(cfg_v6) = cfg_v6 {
+            let changed = pool.update_proxy_maps(HashMap::new(), Some(cfg_v6.map)).await;
+            if changed {
+                info!("ME config updated (v6), reconciling connections");
+                pool.reconcile_connections(&rng).await;
+            } else {
+                debug!("ME config v6 unchanged");
+            }
         }
+        pool.reset_stun_state();
 
         // Update proxy-secret
         match download_proxy_secret().await {
@@ -111,3 +174,35 @@ pub async fn me_config_updater(pool: Arc<MePool>, rng: Arc<SecureRandom>, interv
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parse_ipv6_bracketed() {
+        let line = "proxy_for 2 [2001:67c:04e8:f002::d]:80;";
+        let res = parse_proxy_line(line).unwrap();
+        assert_eq!(res.0, 2);
+        assert_eq!(res.1, "2001:67c:04e8:f002::d".parse::<IpAddr>().unwrap());
+        assert_eq!(res.2, 80);
+    }
+
+    #[test]
+    fn parse_ipv6_plain() {
+        let line = "proxy_for 2 2001:67c:04e8:f002::d:80;";
+        let res = parse_proxy_line(line).unwrap();
+        assert_eq!(res.0, 2);
+        assert_eq!(res.1, "2001:67c:04e8:f002::d".parse::<IpAddr>().unwrap());
+        assert_eq!(res.2, 80);
+    }
+
+    #[test]
+    fn parse_ipv4() {
+        let line = "proxy_for 4 91.108.4.195:8888;";
+        let res = parse_proxy_line(line).unwrap();
+        assert_eq!(res.0, 4);
+        assert_eq!(res.1, "91.108.4.195".parse::<IpAddr>().unwrap());
+        assert_eq!(res.2, 8888);
+    }
+}

src/transport/middle_proxy/handshake.rs

@@ -10,12 +10,13 @@ use std::os::raw::c_int;
 
 use bytes::BytesMut;
 use tokio::io::{AsyncReadExt, AsyncWriteExt, ReadHalf, WriteHalf};
-use tokio::net::TcpStream;
+use tokio::net::{TcpStream, TcpSocket};
 use tokio::time::timeout;
 use tracing::{debug, info, warn};
 
 use crate::crypto::{SecureRandom, build_middleproxy_prekey, derive_middleproxy_keys, sha256};
 use crate::error::{ProxyError, Result};
+use crate::network::IpFamily;
 use crate::protocol::constants::{
     ME_CONNECT_TIMEOUT_SECS, ME_HANDSHAKE_TIMEOUT_SECS, RPC_CRYPTO_AES_U32, RPC_HANDSHAKE_ERROR_U32,
     RPC_HANDSHAKE_U32, RPC_PING_U32, RPC_PONG_U32, RPC_NONCE_U32,
@@ -43,7 +44,28 @@ impl MePool {
     /// TCP connect with timeout + return RTT in milliseconds.
     pub(crate) async fn connect_tcp(&self, addr: SocketAddr) -> Result<(TcpStream, f64)> {
         let start = Instant::now();
-        let stream = timeout(Duration::from_secs(ME_CONNECT_TIMEOUT_SECS), TcpStream::connect(addr))
+        let connect_fut = async {
+            if addr.is_ipv6() {
+                if let Some(v6) = self.detected_ipv6 {
+                    match TcpSocket::new_v6() {
+                        Ok(sock) => {
+                            if let Err(e) = sock.bind(SocketAddr::new(IpAddr::V6(v6), 0)) {
+                                debug!(error = %e, bind_ip = %v6, "ME IPv6 bind failed, falling back to default bind");
+                            } else {
+                                match sock.connect(addr).await {
+                                    Ok(stream) => return Ok(stream),
+                                    Err(e) => debug!(error = %e, target = %addr, "ME IPv6 bound connect failed, retrying default connect"),
+                                }
+                            }
+                        }
+                        Err(e) => debug!(error = %e, "ME IPv6 socket creation failed, falling back to default connect"),
+                    }
+                }
+            }
+            TcpStream::connect(addr).await
+        };
+
+        let stream = timeout(Duration::from_secs(ME_CONNECT_TIMEOUT_SECS), connect_fut)
             .await
             .map_err(|_| ProxyError::ConnectionTimeout { addr: addr.to_string() })??;
         let connect_ms = start.elapsed().as_secs_f64() * 1000.0;
@@ -101,8 +123,13 @@ impl MePool {
         let peer_addr = stream.peer_addr().map_err(ProxyError::Io)?;
 
         let _ = self.maybe_detect_nat_ip(local_addr.ip()).await;
+        let family = if local_addr.ip().is_ipv4() {
+            IpFamily::V4
+        } else {
+            IpFamily::V6
+        };
         let reflected = if self.nat_probe {
-            self.maybe_reflect_public_addr().await
+            self.maybe_reflect_public_addr(family).await
         } else {
             None
         };
@@ -121,7 +148,7 @@ impl MePool {
         let nonce_payload = build_nonce_payload(ks, crypto_ts, &my_nonce);
         let nonce_frame = build_rpc_frame(-2, &nonce_payload);
         let dump = hex_dump(&nonce_frame[..nonce_frame.len().min(44)]);
-        info!(
+        debug!(
             key_selector = format_args!("0x{ks:08x}"),
             crypto_ts,
             frame_len = nonce_frame.len(),

src/transport/middle_proxy/health.rs

@@ -1,113 +1,144 @@
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::net::SocketAddr;
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 
 use tracing::{debug, info, warn};
 use rand::seq::SliceRandom;
+use rand::Rng;
 
 use crate::crypto::SecureRandom;
+use crate::network::IpFamily;
 
 use super::MePool;
 
-pub async fn me_health_monitor(pool: Arc<MePool>, rng: Arc<SecureRandom>, _min_connections: usize) {
-    let mut backoff: HashMap<i32, u64> = HashMap::new();
-    let mut last_attempt: HashMap<i32, Instant> = HashMap::new();
-    loop {
-        tokio::time::sleep(Duration::from_secs(30)).await;
-        // Per-DC coverage check
-        let map = pool.proxy_map_v4.read().await.clone();
-        let writer_addrs: std::collections::HashSet<SocketAddr> = pool
-            .writers
-            .read()
-            .await
-            .iter()
-            .map(|w| w.addr)
-            .collect();
+const HEALTH_INTERVAL_SECS: u64 = 1;
+const JITTER_FRAC_NUM: u64 = 2; // jitter up to 50% of backoff
+const MAX_CONCURRENT_PER_DC_DEFAULT: usize = 1;
 
-        for (dc, addrs) in map.iter() {
-            let dc_addrs: Vec<SocketAddr> = addrs
+pub async fn me_health_monitor(pool: Arc<MePool>, rng: Arc<SecureRandom>, _min_connections: usize) {
+    let mut backoff: HashMap<(i32, IpFamily), u64> = HashMap::new();
+    let mut next_attempt: HashMap<(i32, IpFamily), Instant> = HashMap::new();
+    let mut inflight: HashMap<(i32, IpFamily), usize> = HashMap::new();
+    loop {
+        tokio::time::sleep(Duration::from_secs(HEALTH_INTERVAL_SECS)).await;
+        check_family(
+            IpFamily::V4,
+            &pool,
+            &rng,
+            &mut backoff,
+            &mut next_attempt,
+            &mut inflight,
+        )
+        .await;
+        check_family(
+            IpFamily::V6,
+            &pool,
+            &rng,
+            &mut backoff,
+            &mut next_attempt,
+            &mut inflight,
+        )
+        .await;
+    }
+}
+
+async fn check_family(
+    family: IpFamily,
+    pool: &Arc<MePool>,
+    rng: &Arc<SecureRandom>,
+    backoff: &mut HashMap<(i32, IpFamily), u64>,
+    next_attempt: &mut HashMap<(i32, IpFamily), Instant>,
+    inflight: &mut HashMap<(i32, IpFamily), usize>,
+) {
+    let enabled = match family {
+        IpFamily::V4 => pool.decision.ipv4_me,
+        IpFamily::V6 => pool.decision.ipv6_me,
+    };
+    if !enabled {
+        return;
+    }
+
+    let map = match family {
+        IpFamily::V4 => pool.proxy_map_v4.read().await.clone(),
+        IpFamily::V6 => pool.proxy_map_v6.read().await.clone(),
+    };
+    let writer_addrs: HashSet<SocketAddr> = pool
+        .writers
+        .read()
+        .await
+        .iter()
+        .map(|w| w.addr)
+        .collect();
+
+    let entries: Vec<(i32, Vec<SocketAddr>)> = map
+        .iter()
+        .map(|(dc, addrs)| {
+            let list = addrs
                 .iter()
                 .map(|(ip, port)| SocketAddr::new(*ip, *port))
-                .collect();
-            let has_coverage = dc_addrs.iter().any(|a| writer_addrs.contains(a));
-            if !has_coverage {
-                let delay = *backoff.get(dc).unwrap_or(&30);
-                let now = Instant::now();
-                if let Some(last) = last_attempt.get(dc) {
-                    if now.duration_since(*last).as_secs() < delay {
-                        continue;
-                    }
-                }
-                warn!(dc = %dc, delay, "DC has no ME coverage, reconnecting...");
-                let mut shuffled = dc_addrs.clone();
-                shuffled.shuffle(&mut rand::rng());
-                let mut reconnected = false;
-                for addr in shuffled {
-                    match pool.connect_one(addr, &rng).await {
-                        Ok(()) => {
-                            info!(%addr, dc = %dc, "ME reconnected for DC coverage");
-                            backoff.insert(*dc, 30);
-                            last_attempt.insert(*dc, now);
-                            reconnected = true;
-                            break;
-                        }
-                        Err(e) => debug!(%addr, dc = %dc, error = %e, "ME reconnect failed"),
-                    }
-                }
-                if !reconnected {
-                    let next = (*backoff.get(dc).unwrap_or(&30)).saturating_mul(2).min(300);
-                    backoff.insert(*dc, next);
-                    last_attempt.insert(*dc, now);
-                }
+                .collect::<Vec<_>>();
+            (*dc, list)
+        })
+        .collect();
+
+    for (dc, dc_addrs) in entries {
+        let has_coverage = dc_addrs.iter().any(|a| writer_addrs.contains(a));
+        if has_coverage {
+            continue;
+        }
+
+        let key = (dc, family);
+        let now = Instant::now();
+        if let Some(ts) = next_attempt.get(&key) {
+            if now < *ts {
+                continue;
             }
         }
 
-        // IPv6 coverage check (if available)
-        let map_v6 = pool.proxy_map_v6.read().await.clone();
-        let writer_addrs_v6: std::collections::HashSet<SocketAddr> = pool
-            .writers
-            .read()
-            .await
-            .iter()
-            .map(|w| w.addr)
-            .collect();
-        for (dc, addrs) in map_v6.iter() {
-            let dc_addrs: Vec<SocketAddr> = addrs
-                .iter()
-                .map(|(ip, port)| SocketAddr::new(*ip, *port))
-                .collect();
-            let has_coverage = dc_addrs.iter().any(|a| writer_addrs_v6.contains(a));
-            if !has_coverage {
-                let delay = *backoff.get(dc).unwrap_or(&30);
-                let now = Instant::now();
-                if let Some(last) = last_attempt.get(dc) {
-                    if now.duration_since(*last).as_secs() < delay {
-                        continue;
-                    }
+        let max_concurrent = pool.me_reconnect_max_concurrent_per_dc.max(1) as usize;
+        if *inflight.get(&key).unwrap_or(&0) >= max_concurrent {
+            return;
+        }
+        *inflight.entry(key).or_insert(0) += 1;
+
+        let mut shuffled = dc_addrs.clone();
+        shuffled.shuffle(&mut rand::rng());
+        let mut success = false;
+        for addr in shuffled {
+            let res = tokio::time::timeout(pool.me_one_timeout, pool.connect_one(addr, rng.as_ref())).await;
+            match res {
+                Ok(Ok(())) => {
+                    info!(%addr, dc = %dc, ?family, "ME reconnected for DC coverage");
+                    pool.stats.increment_me_reconnect_success();
+                    backoff.insert(key, pool.me_reconnect_backoff_base.as_millis() as u64);
+                    let jitter = pool.me_reconnect_backoff_base.as_millis() as u64 / JITTER_FRAC_NUM;
+                    let wait = pool.me_reconnect_backoff_base
+                        + Duration::from_millis(rand::rng().random_range(0..=jitter.max(1)));
+                    next_attempt.insert(key, now + wait);
+                    success = true;
+                    break;
                 }
-                warn!(dc = %dc, delay, "IPv6 DC has no ME coverage, reconnecting...");
-                let mut shuffled = dc_addrs.clone();
-                shuffled.shuffle(&mut rand::rng());
-                let mut reconnected = false;
-                for addr in shuffled {
-                    match pool.connect_one(addr, &rng).await {
-                        Ok(()) => {
-                            info!(%addr, dc = %dc, "ME reconnected for IPv6 DC coverage");
-                            backoff.insert(*dc, 30);
-                            last_attempt.insert(*dc, now);
-                            reconnected = true;
-                            break;
-                        }
-                        Err(e) => debug!(%addr, dc = %dc, error = %e, "ME reconnect failed (IPv6)"),
-                    }
-                }
-                if !reconnected {
-                    let next = (*backoff.get(dc).unwrap_or(&30)).saturating_mul(2).min(300);
-                    backoff.insert(*dc, next);
-                    last_attempt.insert(*dc, now);
+                Ok(Err(e)) => {
+                    pool.stats.increment_me_reconnect_attempt();
+                    debug!(%addr, dc = %dc, error = %e, ?family, "ME reconnect failed")
                 }
+                Err(_) => debug!(%addr, dc = %dc, ?family, "ME reconnect timed out"),
             }
         }
+        if !success {
+            pool.stats.increment_me_reconnect_attempt();
+            let curr = *backoff.get(&key).unwrap_or(&(pool.me_reconnect_backoff_base.as_millis() as u64));
+            let next_ms = (curr.saturating_mul(2)).min(pool.me_reconnect_backoff_cap.as_millis() as u64);
+            backoff.insert(key, next_ms);
+            let jitter = next_ms / JITTER_FRAC_NUM;
+            let wait = Duration::from_millis(next_ms)
+                + Duration::from_millis(rand::rng().random_range(0..=jitter.max(1)));
+            next_attempt.insert(key, now + wait);
+            warn!(dc = %dc, backoff_ms = next_ms, ?family, "DC has no ME coverage, scheduled reconnect");
+        }
+        if let Some(v) = inflight.get_mut(&key) {
+            *v = v.saturating_sub(1);
+        }
     }
 }

src/transport/middle_proxy/mod.rs

@@ -19,7 +19,7 @@ use bytes::Bytes;
 pub use health::me_health_monitor;
 pub use ping::{run_me_ping, format_sample_line, MePingReport, MePingSample, MePingFamily};
 pub use pool::MePool;
-pub use pool_nat::{stun_probe, detect_public_ip, StunProbeResult};
+pub use pool_nat::{stun_probe, detect_public_ip};
 pub use registry::ConnRegistry;
 pub use secret::fetch_proxy_secret;
 pub use config_updater::{fetch_proxy_config, me_config_updater};

src/transport/middle_proxy/ping.rs

@@ -1,3 +1,4 @@
+use std::collections::HashMap;
 use std::net::{IpAddr, SocketAddr};
 use std::sync::Arc;
 
@@ -92,8 +93,16 @@ mod tests {
 pub async fn run_me_ping(pool: &Arc<MePool>, rng: &SecureRandom) -> Vec<MePingReport> {
     let mut reports = Vec::new();
 
-    let v4_map = pool.proxy_map_v4.read().await.clone();
-    let v6_map = pool.proxy_map_v6.read().await.clone();
+    let v4_map = if pool.decision.ipv4_me {
+        pool.proxy_map_v4.read().await.clone()
+    } else {
+        HashMap::new()
+    };
+    let v6_map = if pool.decision.ipv6_me {
+        pool.proxy_map_v6.read().await.clone()
+    } else {
+        HashMap::new()
+    };
 
     let mut grouped: Vec<(MePingFamily, i32, Vec<(IpAddr, u16)>)> = Vec::new();
     for (dc, addrs) in v4_map {

src/transport/middle_proxy/pool.rs

@@ -1,57 +1,89 @@
 use std::collections::HashMap;
-use std::net::{IpAddr, SocketAddr};
+use std::net::{IpAddr, Ipv6Addr, SocketAddr};
 use std::sync::Arc;
-use std::sync::atomic::{AtomicBool, AtomicI32, AtomicU64, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicI32, AtomicU64, AtomicUsize, Ordering};
 use bytes::BytesMut;
 use rand::Rng;
 use rand::seq::SliceRandom;
-use tokio::sync::{Mutex, RwLock};
+use tokio::sync::{Mutex, RwLock, mpsc, Notify};
 use tokio_util::sync::CancellationToken;
 use tracing::{debug, info, warn};
-use std::time::Duration;
+use std::time::{Duration, Instant};
 
 use crate::crypto::SecureRandom;
 use crate::error::{ProxyError, Result};
+use crate::network::probe::NetworkDecision;
+use crate::network::IpFamily;
 use crate::protocol::constants::*;
 
 use super::ConnRegistry;
 use super::registry::{BoundConn, ConnMeta};
-use super::codec::RpcWriter;
+use super::codec::{RpcWriter, WriterCommand};
 use super::reader::reader_loop;
 use super::MeResponse;
-
 const ME_ACTIVE_PING_SECS: u64 = 25;
 const ME_ACTIVE_PING_JITTER_SECS: i64 = 5;
+const ME_KEEPALIVE_PAYLOAD_LEN: usize = 4;
 
 #[derive(Clone)]
 pub struct MeWriter {
     pub id: u64,
     pub addr: SocketAddr,
-    pub writer: Arc<Mutex<RpcWriter>>,
+    pub tx: mpsc::Sender<WriterCommand>,
     pub cancel: CancellationToken,
     pub degraded: Arc<AtomicBool>,
+    pub draining: Arc<AtomicBool>,
 }
 
 pub struct MePool {
     pub(super) registry: Arc<ConnRegistry>,
     pub(super) writers: Arc<RwLock<Vec<MeWriter>>>,
     pub(super) rr: AtomicU64,
+    pub(super) decision: NetworkDecision,
+    pub(super) rng: Arc<SecureRandom>,
     pub(super) proxy_tag: Option<Vec<u8>>,
     pub(super) proxy_secret: Arc<RwLock<Vec<u8>>>,
     pub(super) nat_ip_cfg: Option<IpAddr>,
     pub(super) nat_ip_detected: Arc<RwLock<Option<IpAddr>>>,
     pub(super) nat_probe: bool,
     pub(super) nat_stun: Option<String>,
+    pub(super) nat_stun_servers: Vec<String>,
+    pub(super) detected_ipv6: Option<Ipv6Addr>,
+    pub(super) nat_probe_attempts: std::sync::atomic::AtomicU8,
+    pub(super) nat_probe_disabled: std::sync::atomic::AtomicBool,
+    pub(super) stun_backoff_until: Arc<RwLock<Option<Instant>>>,
+    pub(super) me_one_retry: u8,
+    pub(super) me_one_timeout: Duration,
+    pub(super) me_keepalive_enabled: bool,
+    pub(super) me_keepalive_interval: Duration,
+    pub(super) me_keepalive_jitter: Duration,
+    pub(super) me_keepalive_payload_random: bool,
+    pub(super) me_warmup_stagger_enabled: bool,
+    pub(super) me_warmup_step_delay: Duration,
+    pub(super) me_warmup_step_jitter: Duration,
+    pub(super) me_reconnect_max_concurrent_per_dc: u32,
+    pub(super) me_reconnect_backoff_base: Duration,
+    pub(super) me_reconnect_backoff_cap: Duration,
+    pub(super) me_reconnect_fast_retry_count: u32,
     pub(super) proxy_map_v4: Arc<RwLock<HashMap<i32, Vec<(IpAddr, u16)>>>>,
     pub(super) proxy_map_v6: Arc<RwLock<HashMap<i32, Vec<(IpAddr, u16)>>>>,
     pub(super) default_dc: AtomicI32,
     pub(super) next_writer_id: AtomicU64,
     pub(super) ping_tracker: Arc<Mutex<HashMap<i64, (std::time::Instant, u64)>>>,
     pub(super) rtt_stats: Arc<Mutex<HashMap<u64, (f64, f64)>>>,
-    pub(super) nat_reflection_cache: Arc<Mutex<Option<(std::time::Instant, std::net::SocketAddr)>>>,
+    pub(super) nat_reflection_cache: Arc<Mutex<NatReflectionCache>>,
+    pub(super) writer_available: Arc<Notify>,
+    pub(super) conn_count: AtomicUsize,
+    pub(super) stats: Arc<crate::stats::Stats>,
     pool_size: usize,
 }
 
+#[derive(Debug, Default)]
+pub struct NatReflectionCache {
+    pub v4: Option<(std::time::Instant, std::net::SocketAddr)>,
+    pub v6: Option<(std::time::Instant, std::net::SocketAddr)>,
+}
+
 impl MePool {
     pub fn new(
         proxy_tag: Option<Vec<u8>>,
@@ -59,20 +91,59 @@ impl MePool {
         nat_ip: Option<IpAddr>,
         nat_probe: bool,
         nat_stun: Option<String>,
+        nat_stun_servers: Vec<String>,
+        detected_ipv6: Option<Ipv6Addr>,
+        me_one_retry: u8,
+        me_one_timeout_ms: u64,
         proxy_map_v4: HashMap<i32, Vec<(IpAddr, u16)>>,
         proxy_map_v6: HashMap<i32, Vec<(IpAddr, u16)>>,
         default_dc: Option<i32>,
+        decision: NetworkDecision,
+        rng: Arc<SecureRandom>,
+        stats: Arc<crate::stats::Stats>,
+        me_keepalive_enabled: bool,
+        me_keepalive_interval_secs: u64,
+        me_keepalive_jitter_secs: u64,
+        me_keepalive_payload_random: bool,
+        me_warmup_stagger_enabled: bool,
+        me_warmup_step_delay_ms: u64,
+        me_warmup_step_jitter_ms: u64,
+        me_reconnect_max_concurrent_per_dc: u32,
+        me_reconnect_backoff_base_ms: u64,
+        me_reconnect_backoff_cap_ms: u64,
+        me_reconnect_fast_retry_count: u32,
     ) -> Arc<Self> {
         Arc::new(Self {
             registry: Arc::new(ConnRegistry::new()),
             writers: Arc::new(RwLock::new(Vec::new())),
             rr: AtomicU64::new(0),
+            decision,
+            rng,
             proxy_tag,
             proxy_secret: Arc::new(RwLock::new(proxy_secret)),
             nat_ip_cfg: nat_ip,
             nat_ip_detected: Arc::new(RwLock::new(None)),
             nat_probe,
             nat_stun,
+            nat_stun_servers,
+            detected_ipv6,
+            nat_probe_attempts: std::sync::atomic::AtomicU8::new(0),
+            nat_probe_disabled: std::sync::atomic::AtomicBool::new(false),
+            stun_backoff_until: Arc::new(RwLock::new(None)),
+            me_one_retry,
+            me_one_timeout: Duration::from_millis(me_one_timeout_ms),
+            stats,
+            me_keepalive_enabled,
+            me_keepalive_interval: Duration::from_secs(me_keepalive_interval_secs),
+            me_keepalive_jitter: Duration::from_secs(me_keepalive_jitter_secs),
+            me_keepalive_payload_random,
+            me_warmup_stagger_enabled,
+            me_warmup_step_delay: Duration::from_millis(me_warmup_step_delay_ms),
+            me_warmup_step_jitter: Duration::from_millis(me_warmup_step_jitter_ms),
+            me_reconnect_max_concurrent_per_dc,
+            me_reconnect_backoff_base: Duration::from_millis(me_reconnect_backoff_base_ms),
+            me_reconnect_backoff_cap: Duration::from_millis(me_reconnect_backoff_cap_ms),
+            me_reconnect_fast_retry_count,
             pool_size: 2,
             proxy_map_v4: Arc::new(RwLock::new(proxy_map_v4)),
             proxy_map_v6: Arc::new(RwLock::new(proxy_map_v6)),
@@ -80,7 +151,9 @@ impl MePool {
             next_writer_id: AtomicU64::new(1),
             ping_tracker: Arc::new(Mutex::new(HashMap::new())),
             rtt_stats: Arc::new(Mutex::new(HashMap::new())),
-            nat_reflection_cache: Arc::new(Mutex::new(None)),
+            nat_reflection_cache: Arc::new(Mutex::new(NatReflectionCache::default())),
+            writer_available: Arc::new(Notify::new()),
+            conn_count: AtomicUsize::new(0),
         })
     }
 
@@ -88,6 +161,11 @@ impl MePool {
         self.proxy_tag.is_some()
     }
 
+    pub fn reset_stun_state(&self) {
+        self.nat_probe_attempts.store(0, Ordering::Relaxed);
+        self.nat_probe_disabled.store(false, Ordering::Relaxed);
+    }
+
     pub fn translate_our_addr(&self, addr: SocketAddr) -> SocketAddr {
         let ip = self.translate_ip_for_nat(addr.ip());
         SocketAddr::new(ip, addr.port())
@@ -103,29 +181,34 @@ impl MePool {
 
     pub async fn reconcile_connections(self: &Arc<Self>, rng: &SecureRandom) {
         use std::collections::HashSet;
-        let map = self.proxy_map_v4.read().await.clone();
-        let dc_addrs: Vec<(i32, Vec<(IpAddr, u16)>)> = map
-            .iter()
-            .map(|(dc, addrs)| (*dc, addrs.clone()))
-            .collect();
         let writers = self.writers.read().await;
-        let current: HashSet<SocketAddr> = writers.iter().map(|w| w.addr).collect();
+        let current: HashSet<SocketAddr> = writers
+            .iter()
+            .filter(|w| !w.draining.load(Ordering::Relaxed))
+            .map(|w| w.addr)
+            .collect();
         drop(writers);
 
-        for (_dc, addrs) in map.iter() {
-            let dc_addrs: Vec<SocketAddr> = addrs
-                .iter()
-                .map(|(ip, port)| SocketAddr::new(*ip, *port))
-                .collect();
-            if !dc_addrs.iter().any(|a| current.contains(a)) {
-                let mut shuffled = dc_addrs.clone();
-                shuffled.shuffle(&mut rand::rng());
-                for addr in shuffled {
-                    if self.connect_one(addr, rng).await.is_ok() {
-                        break;
+        for family in self.family_order() {
+            let map = self.proxy_map_for_family(family).await;
+            for (_dc, addrs) in map.iter() {
+                let dc_addrs: Vec<SocketAddr> = addrs
+                    .iter()
+                    .map(|(ip, port)| SocketAddr::new(*ip, *port))
+                    .collect();
+                if !dc_addrs.iter().any(|a| current.contains(a)) {
+                    let mut shuffled = dc_addrs.clone();
+                    shuffled.shuffle(&mut rand::rng());
+                    for addr in shuffled {
+                        if self.connect_one(addr, rng).await.is_ok() {
+                            break;
+                        }
                     }
                 }
             }
+            if !self.decision.effective_multipath && !current.is_empty() {
+                break;
+            }
         }
     }
 
@@ -146,12 +229,36 @@ impl MePool {
             let mut guard = self.proxy_map_v6.write().await;
             if !v6.is_empty() && *guard != v6 {
                 *guard = v6;
+                changed = true;
+            }
+        }
+        // Ensure negative DC entries mirror positives when absent (Telegram convention).
+        {
+            let mut guard = self.proxy_map_v4.write().await;
+            let keys: Vec<i32> = guard.keys().cloned().collect();
+            for k in keys.iter().cloned().filter(|k| *k > 0) {
+                if !guard.contains_key(&-k) {
+                    if let Some(addrs) = guard.get(&k).cloned() {
+                        guard.insert(-k, addrs);
+                    }
+                }
+            }
+        }
+        {
+            let mut guard = self.proxy_map_v6.write().await;
+            let keys: Vec<i32> = guard.keys().cloned().collect();
+            for k in keys.iter().cloned().filter(|k| *k > 0) {
+                if !guard.contains_key(&-k) {
+                    if let Some(addrs) = guard.get(&k).cloned() {
+                        guard.insert(-k, addrs);
+                    }
+                }
             }
         }
         changed
     }
 
-    pub async fn update_secret(&self, new_secret: Vec<u8>) -> bool {
+    pub async fn update_secret(self: &Arc<Self>, new_secret: Vec<u8>) -> bool {
         if new_secret.len() < 32 {
             warn!(len = new_secret.len(), "proxy-secret update ignored (too short)");
             return false;
@@ -166,10 +273,14 @@ impl MePool {
         false
     }
 
-    pub async fn reconnect_all(&self) {
-        // Graceful: do not drop all at once. New connections will use updated secret.
-        // Existing writers remain until health monitor replaces them.
-        // No-op here to avoid total outage.
+    pub async fn reconnect_all(self: &Arc<Self>) {
+        let ws = self.writers.read().await.clone();
+        for w in ws {
+            if let Ok(()) = self.connect_one(w.addr, self.rng.as_ref()).await {
+                self.mark_writer_draining(w.id).await;
+                tokio::time::sleep(Duration::from_secs(2)).await;
+            }
+        }
     }
 
     pub(super) async fn key_selector(&self) -> u32 {
@@ -181,47 +292,108 @@ impl MePool {
         }
     }
 
+    pub(super) fn family_order(&self) -> Vec<IpFamily> {
+        let mut order = Vec::new();
+        if self.decision.prefer_ipv6() {
+            if self.decision.ipv6_me {
+                order.push(IpFamily::V6);
+            }
+            if self.decision.ipv4_me {
+                order.push(IpFamily::V4);
+            }
+        } else {
+            if self.decision.ipv4_me {
+                order.push(IpFamily::V4);
+            }
+            if self.decision.ipv6_me {
+                order.push(IpFamily::V6);
+            }
+        }
+        order
+    }
+
+    async fn proxy_map_for_family(&self, family: IpFamily) -> HashMap<i32, Vec<(IpAddr, u16)>> {
+        match family {
+            IpFamily::V4 => self.proxy_map_v4.read().await.clone(),
+            IpFamily::V6 => self.proxy_map_v6.read().await.clone(),
+        }
+    }
+
     pub async fn init(self: &Arc<Self>, pool_size: usize, rng: &Arc<SecureRandom>) -> Result<()> {
-        let map = self.proxy_map_v4.read().await.clone();
-        let dc_addrs: Vec<(i32, Vec<(IpAddr, u16)>)> = map
-            .iter()
-            .map(|(dc, addrs)| (*dc, addrs.clone()))
-            .collect();
+        let family_order = self.family_order();
         let ks = self.key_selector().await;
         info!(
-            me_servers = map.len(),
+            me_servers = self.proxy_map_v4.read().await.len(),
             pool_size,
             key_selector = format_args!("0x{ks:08x}"),
             secret_len = self.proxy_secret.read().await.len(),
             "Initializing ME pool"
         );
 
-        // Ensure at least one connection per DC; run DCs in parallel.
-        let mut join = tokio::task::JoinSet::new();
-        for (dc, addrs) in dc_addrs.iter().cloned() {
-            if addrs.is_empty() {
-                continue;
-            }
-            let pool = Arc::clone(self);
-            let rng_clone = Arc::clone(rng);
-            join.spawn(async move {
-                pool.connect_primary_for_dc(dc, addrs, rng_clone).await;
-            });
-        }
-        while let Some(_res) = join.join_next().await {}
+        for family in family_order {
+            let map = self.proxy_map_for_family(family).await;
+            let dc_addrs: Vec<(i32, Vec<(IpAddr, u16)>)> = map
+                .iter()
+                .map(|(dc, addrs)| (*dc, addrs.clone()))
+                .collect();
 
-        // Additional connections up to pool_size total (round-robin across DCs)
-        for (dc, addrs) in dc_addrs.iter() {
-            for (ip, port) in addrs {
+            // Ensure at least one connection per DC; run DCs in parallel.
+            let mut join = tokio::task::JoinSet::new();
+            let mut dc_failures = 0usize;
+            for (dc, addrs) in dc_addrs.iter().cloned() {
+                if addrs.is_empty() {
+                    continue;
+                }
+                let pool = Arc::clone(self);
+                let rng_clone = Arc::clone(rng);
+                join.spawn(async move {
+                    pool.connect_primary_for_dc(dc, addrs, rng_clone).await
+                });
+            }
+            while let Some(res) = join.join_next().await {
+                if let Ok(false) = res {
+                    dc_failures += 1;
+                }
+            }
+            if dc_failures > 2 {
+                return Err(ProxyError::Proxy("Too many ME DC init failures, falling back to direct".into()));
+            }
+
+        // Additional connections up to pool_size total (round-robin across DCs), staggered to de-phase lifecycles.
+        if self.me_warmup_stagger_enabled {
+            let mut delay_ms = 0u64;
+            for (dc, addrs) in dc_addrs.iter() {
+                for (ip, port) in addrs {
+                    if self.connection_count() >= pool_size {
+                        break;
+                    }
+                    let addr = SocketAddr::new(*ip, *port);
+                    let jitter = rand::rng().random_range(0..=self.me_warmup_step_jitter.as_millis() as u64);
+                    delay_ms = delay_ms.saturating_add(self.me_warmup_step_delay.as_millis() as u64 + jitter);
+                    tokio::time::sleep(Duration::from_millis(delay_ms)).await;
+                    if let Err(e) = self.connect_one(addr, rng.as_ref()).await {
+                        debug!(%addr, dc = %dc, error = %e, "Extra ME connect failed (staggered)");
+                    }
+                }
+            }
+        } else {
+            for (dc, addrs) in dc_addrs.iter() {
+                for (ip, port) in addrs {
+                    if self.connection_count() >= pool_size {
+                        break;
+                    }
+                    let addr = SocketAddr::new(*ip, *port);
+                    if let Err(e) = self.connect_one(addr, rng.as_ref()).await {
+                        debug!(%addr, dc = %dc, error = %e, "Extra ME connect failed");
+                    }
+                }
                 if self.connection_count() >= pool_size {
                     break;
                 }
-                let addr = SocketAddr::new(*ip, *port);
-                if let Err(e) = self.connect_one(addr, rng.as_ref()).await {
-                    debug!(%addr, dc = %dc, error = %e, "Extra ME connect failed");
-                }
             }
-            if self.connection_count() >= pool_size {
+        }
+
+            if !self.decision.effective_multipath && self.connection_count() > 0 {
                 break;
             }
         }
@@ -244,20 +416,62 @@ impl MePool {
         let writer_id = self.next_writer_id.fetch_add(1, Ordering::Relaxed);
         let cancel = CancellationToken::new();
         let degraded = Arc::new(AtomicBool::new(false));
-        let rpc_w = Arc::new(Mutex::new(RpcWriter {
+        let draining = Arc::new(AtomicBool::new(false));
+        let (tx, mut rx) = mpsc::channel::<WriterCommand>(4096);
+        let tx_for_keepalive = tx.clone();
+        let keepalive_random = self.me_keepalive_payload_random;
+        let stats = self.stats.clone();
+        let mut rpc_writer = RpcWriter {
             writer: hs.wr,
             key: hs.write_key,
             iv: hs.write_iv,
             seq_no: 0,
-        }));
+        };
+        let cancel_wr = cancel.clone();
+        tokio::spawn(async move {
+            loop {
+                tokio::select! {
+                    cmd = rx.recv() => {
+                        match cmd {
+                            Some(WriterCommand::Data(payload)) => {
+                                if rpc_writer.send(&payload).await.is_err() { break; }
+                            }
+                            Some(WriterCommand::DataAndFlush(payload)) => {
+                                if rpc_writer.send_and_flush(&payload).await.is_err() { break; }
+                            }
+                            Some(WriterCommand::Keepalive) => {
+                                let mut payload = [0u8; ME_KEEPALIVE_PAYLOAD_LEN];
+                                if keepalive_random {
+                                    rand::rng().fill(&mut payload);
+                                }
+                                match rpc_writer.send_keepalive(payload).await {
+                                    Ok(()) => {
+                                        stats.increment_me_keepalive_sent();
+                                    }
+                                    Err(_) => {
+                                        stats.increment_me_keepalive_failed();
+                                        break;
+                                    }
+                                }
+                            }
+                            Some(WriterCommand::Close) | None => break,
+                        }
+                    }
+                    _ = cancel_wr.cancelled() => break,
+                }
+            }
+        });
         let writer = MeWriter {
             id: writer_id,
             addr,
-            writer: rpc_w.clone(),
+            tx: tx.clone(),
             cancel: cancel.clone(),
             degraded: degraded.clone(),
+            draining: draining.clone(),
         };
         self.writers.write().await.push(writer.clone());
+        self.conn_count.fetch_add(1, Ordering::Relaxed);
+        self.writer_available.notify_waiters();
 
         let reg = self.registry.clone();
         let writers_arc = self.writers_arc();
@@ -265,11 +479,19 @@ impl MePool {
         let rtt_stats = self.rtt_stats.clone();
         let pool = Arc::downgrade(self);
         let cancel_ping = cancel.clone();
-        let rpc_w_ping = rpc_w.clone();
+        let tx_ping = tx.clone();
         let ping_tracker_ping = ping_tracker.clone();
+        let cleanup_done = Arc::new(AtomicBool::new(false));
+        let cleanup_for_reader = cleanup_done.clone();
+        let cleanup_for_ping = cleanup_done.clone();
+        let keepalive_enabled = self.me_keepalive_enabled;
+        let keepalive_interval = self.me_keepalive_interval;
+        let keepalive_jitter = self.me_keepalive_jitter;
+        let cancel_reader_token = cancel.clone();
+        let cancel_ping_token = cancel_ping.clone();
+        let cancel_keepalive_token = cancel.clone();
 
         tokio::spawn(async move {
-            let cancel_reader = cancel.clone();
             let res = reader_loop(
                 hs.rd,
                 hs.read_key,
@@ -277,16 +499,21 @@ impl MePool {
                 reg.clone(),
                 BytesMut::new(),
                 BytesMut::new(),
-                rpc_w.clone(),
+                tx.clone(),
                 ping_tracker.clone(),
                 rtt_stats.clone(),
                 writer_id,
                 degraded.clone(),
-                cancel_reader.clone(),
+                cancel_reader_token.clone(),
             )
             .await;
             if let Some(pool) = pool.upgrade() {
-                pool.remove_writer_and_reroute(writer_id).await;
+                if cleanup_for_reader
+                    .compare_exchange(false, true, Ordering::AcqRel, Ordering::Relaxed)
+                    .is_ok()
+                {
+                    pool.remove_writer_and_close_clients(writer_id).await;
+                }
             }
             if let Err(e) = res {
                 warn!(error = %e, "ME reader ended");
@@ -304,30 +531,56 @@ impl MePool {
                     .random_range(-ME_ACTIVE_PING_JITTER_SECS..=ME_ACTIVE_PING_JITTER_SECS);
                 let wait = (ME_ACTIVE_PING_SECS as i64 + jitter).max(5) as u64;
                 tokio::select! {
-                    _ = cancel_ping.cancelled() => {
+                    _ = cancel_ping_token.cancelled() => {
                         break;
                     }
                     _ = tokio::time::sleep(Duration::from_secs(wait)) => {}
                 }
+                let sent_id = ping_id;
                 let mut p = Vec::with_capacity(12);
                 p.extend_from_slice(&RPC_PING_U32.to_le_bytes());
-                p.extend_from_slice(&ping_id.to_le_bytes());
-                ping_id = ping_id.wrapping_add(1);
+                p.extend_from_slice(&sent_id.to_le_bytes());
                 {
                     let mut tracker = ping_tracker_ping.lock().await;
-                    tracker.insert(ping_id, (std::time::Instant::now(), writer_id));
+                    tracker.retain(|_, (ts, _)| ts.elapsed() < Duration::from_secs(120));
+                    tracker.insert(sent_id, (std::time::Instant::now(), writer_id));
                 }
-                if let Err(e) = rpc_w_ping.lock().await.send(&p).await {
-                    debug!(error = %e, "Active ME ping failed, removing dead writer");
+                ping_id = ping_id.wrapping_add(1);
+                if tx_ping.send(WriterCommand::DataAndFlush(p)).await.is_err() {
+                    debug!("Active ME ping failed, removing dead writer");
                     cancel_ping.cancel();
                     if let Some(pool) = pool_ping.upgrade() {
-                        pool.remove_writer_and_reroute(writer_id).await;
+                        if cleanup_for_ping
+                            .compare_exchange(false, true, Ordering::AcqRel, Ordering::Relaxed)
+                            .is_ok()
+                        {
+                            pool.remove_writer_and_close_clients(writer_id).await;
+                        }
                     }
                     break;
                 }
             }
         });
 
+        if keepalive_enabled {
+            let tx_keepalive = tx_for_keepalive;
+            let cancel_keepalive = cancel_keepalive_token;
+            tokio::spawn(async move {
+                // Per-writer jittered start to avoid phase sync.
+                let initial_jitter_ms = rand::rng().random_range(0..=keepalive_jitter.as_millis().max(1) as u64);
+                tokio::time::sleep(Duration::from_millis(initial_jitter_ms)).await;
+                loop {
+                    tokio::select! {
+                        _ = cancel_keepalive.cancelled() => break,
+                        _ = tokio::time::sleep(keepalive_interval + Duration::from_millis(rand::rng().random_range(0..=keepalive_jitter.as_millis() as u64))) => {}
+                    }
+                    if tx_keepalive.send(WriterCommand::Keepalive).await.is_err() {
+                        break;
+                    }
+                }
+            });
+        }
+
         Ok(())
     }
 
@@ -336,9 +589,9 @@ impl MePool {
         dc: i32,
         mut addrs: Vec<(IpAddr, u16)>,
         rng: Arc<SecureRandom>,
-    ) {
+    ) -> bool {
         if addrs.is_empty() {
-            return;
+            return false;
         }
         addrs.shuffle(&mut rand::rng());
         for (ip, port) in addrs {
@@ -346,20 +599,20 @@ impl MePool {
             match self.connect_one(addr, rng.as_ref()).await {
                 Ok(()) => {
                     info!(%addr, dc = %dc, "ME connected");
-                    return;
+                    return true;
                 }
                 Err(e) => warn!(%addr, dc = %dc, error = %e, "ME connect failed, trying next"),
             }
         }
         warn!(dc = %dc, "All ME servers for DC failed at init");
+        false
     }
 
-    pub(crate) async fn remove_writer_and_reroute(&self, writer_id: u64) {
-        let mut queue = self.remove_writer_only(writer_id).await;
-        while let Some(bound) = queue.pop() {
-            if !self.reroute_conn(&bound, &mut queue).await {
-                let _ = self.registry.route(bound.conn_id, super::MeResponse::Close).await;
-            }
+    pub(crate) async fn remove_writer_and_close_clients(self: &Arc<Self>, writer_id: u64) {
+        let conns = self.remove_writer_only(writer_id).await;
+        for bound in conns {
+            let _ = self.registry.route(bound.conn_id, super::MeResponse::Close).await;
+            let _ = self.registry.unregister(bound.conn_id).await;
         }
     }
 
@@ -369,84 +622,42 @@ impl MePool {
             if let Some(pos) = ws.iter().position(|w| w.id == writer_id) {
                 let w = ws.remove(pos);
                 w.cancel.cancel();
+                let _ = w.tx.send(WriterCommand::Close).await;
+                self.conn_count.fetch_sub(1, Ordering::Relaxed);
             }
         }
+        self.rtt_stats.lock().await.remove(&writer_id);
         self.registry.writer_lost(writer_id).await
     }
 
-    async fn reroute_conn(&self, bound: &BoundConn, backlog: &mut Vec<BoundConn>) -> bool {
-        let payload = super::wire::build_proxy_req_payload(
-            bound.conn_id,
-            bound.meta.client_addr,
-            bound.meta.our_addr,
-            &[],
-            self.proxy_tag.as_deref(),
-            bound.meta.proto_flags,
-        );
-
-        let mut attempts = 0;
-        loop {
-            let writers_snapshot = {
-                let ws = self.writers.read().await;
-                if ws.is_empty() {
-                    return false;
-                }
-                ws.clone()
-            };
-            let mut candidates = self.candidate_indices_for_dc(&writers_snapshot, bound.meta.target_dc).await;
-            if candidates.is_empty() {
-                return false;
-            }
-            candidates.sort_by_key(|idx| {
-                writers_snapshot[*idx]
-                    .degraded
-                    .load(Ordering::Relaxed)
-                    .then_some(1usize)
-                    .unwrap_or(0)
-            });
-            let start = self.rr.fetch_add(1, Ordering::Relaxed) as usize % candidates.len();
-
-            for offset in 0..candidates.len() {
-                let idx = candidates[(start + offset) % candidates.len()];
-                let w = &writers_snapshot[idx];
-                if let Ok(mut guard) = w.writer.try_lock() {
-                    let send_res = guard.send(&payload).await;
-                    drop(guard);
-                    match send_res {
-                        Ok(()) => {
-                            self.registry
-                                .bind_writer(bound.conn_id, w.id, w.writer.clone(), bound.meta.clone())
-                                .await;
-                            return true;
-                        }
-                        Err(e) => {
-                            warn!(error = %e, writer_id = w.id, "ME reroute send failed");
-                            backlog.extend(self.remove_writer_only(w.id).await);
-                        }
-                    }
-                    continue;
-                }
-            }
-
-            let w = writers_snapshot[candidates[start]].clone();
-            match w.writer.lock().await.send(&payload).await {
-                Ok(()) => {
-                    self.registry
-                        .bind_writer(bound.conn_id, w.id, w.writer.clone(), bound.meta.clone())
-                        .await;
-                    return true;
-                }
-                Err(e) => {
-                    warn!(error = %e, writer_id = w.id, "ME reroute send failed (blocking)");
-                    backlog.extend(self.remove_writer_only(w.id).await);
-                }
-            }
-
-            attempts += 1;
-            if attempts > 3 {
-                return false;
+    pub(crate) async fn mark_writer_draining(self: &Arc<Self>, writer_id: u64) {
+        {
+            let mut ws = self.writers.write().await;
+            if let Some(w) = ws.iter_mut().find(|w| w.id == writer_id) {
+                w.draining.store(true, Ordering::Relaxed);
             }
         }
+
+        let pool = Arc::downgrade(self);
+        tokio::spawn(async move {
+            let deadline = Instant::now() + Duration::from_secs(300);
+            loop {
+                if let Some(p) = pool.upgrade() {
+                    if Instant::now() >= deadline {
+                        warn!(writer_id, "Drain timeout, force-closing");
+                        let _ = p.remove_writer_and_close_clients(writer_id).await;
+                        break;
+                    }
+                    if p.registry.is_writer_empty(writer_id).await {
+                        let _ = p.remove_writer_only(writer_id).await;
+                        break;
+                    }
+                    tokio::time::sleep(Duration::from_secs(1)).await;
+                } else {
+                    break;
+                }
+            }
+        });
     }
 
 }

src/transport/middle_proxy/pool_nat.rs

@@ -1,22 +1,17 @@
 use std::net::{IpAddr, Ipv4Addr};
 use std::time::Duration;
 
-use tracing::{info, warn};
+use tracing::{info, warn, debug};
 
 use crate::error::{ProxyError, Result};
+use crate::network::probe::is_bogon;
+use crate::network::stun::{stun_probe_dual, IpFamily, StunProbeResult};
 
 use super::MePool;
 use std::time::Instant;
-
-#[derive(Debug, Clone, Copy)]
-pub struct StunProbeResult {
-    pub local_addr: std::net::SocketAddr,
-    pub reflected_addr: std::net::SocketAddr,
-}
-
-pub async fn stun_probe(stun_addr: Option<String>) -> Result<Option<StunProbeResult>> {
+pub async fn stun_probe(stun_addr: Option<String>) -> Result<crate::network::stun::DualStunResult> {
     let stun_addr = stun_addr.unwrap_or_else(|| "stun.l.google.com:19302".to_string());
-    fetch_stun_binding(&stun_addr).await
+    stun_probe_dual(&stun_addr).await
 }
 
 pub async fn detect_public_ip() -> Option<IpAddr> {
@@ -35,7 +30,7 @@ impl MePool {
 
         match (ip, nat_ip) {
             (IpAddr::V4(src), IpAddr::V4(dst))
-                if is_privateish(IpAddr::V4(src))
+                if is_bogon(IpAddr::V4(src))
                     || src.is_loopback()
                     || src.is_unspecified() =>
             {
@@ -55,7 +50,7 @@ impl MePool {
     ) -> std::net::SocketAddr {
         let ip = if let Some(r) = reflected {
             // Use reflected IP (not port) only when local address is non-public.
-            if is_privateish(addr.ip()) || addr.ip().is_loopback() || addr.ip().is_unspecified() {
+            if is_bogon(addr.ip()) || addr.ip().is_loopback() || addr.ip().is_unspecified() {
                 r.ip()
             } else {
                 self.translate_ip_for_nat(addr.ip())
@@ -73,7 +68,7 @@ impl MePool {
             return self.nat_ip_cfg;
         }
 
-        if !(is_privateish(local_ip) || local_ip.is_loopback() || local_ip.is_unspecified()) {
+        if !(is_bogon(local_ip) || local_ip.is_loopback() || local_ip.is_unspecified()) {
             return None;
         }
 
@@ -98,37 +93,74 @@ impl MePool {
         }
     }
 
-    pub(super) async fn maybe_reflect_public_addr(&self) -> Option<std::net::SocketAddr> {
+    pub(super) async fn maybe_reflect_public_addr(
+        &self,
+        family: IpFamily,
+    ) -> Option<std::net::SocketAddr> {
         const STUN_CACHE_TTL: Duration = Duration::from_secs(600);
+        // Backoff window
+        if let Some(until) = *self.stun_backoff_until.read().await {
+            if Instant::now() < until {
+                if let Ok(cache) = self.nat_reflection_cache.try_lock() {
+                    let slot = match family {
+                        IpFamily::V4 => cache.v4,
+                        IpFamily::V6 => cache.v6,
+                    };
+                    return slot.map(|(_, addr)| addr);
+                }
+                return None;
+            }
+        }
+
         if let Ok(mut cache) = self.nat_reflection_cache.try_lock() {
-            if let Some((ts, addr)) = *cache {
+            let slot = match family {
+                IpFamily::V4 => &mut cache.v4,
+                IpFamily::V6 => &mut cache.v6,
+            };
+            if let Some((ts, addr)) = slot {
                 if ts.elapsed() < STUN_CACHE_TTL {
-                    return Some(addr);
+                    return Some(*addr);
                 }
             }
         }
 
-        let stun_addr = self
-            .nat_stun
-            .clone()
-            .unwrap_or_else(|| "stun.l.google.com:19302".to_string());
-        match fetch_stun_binding(&stun_addr).await {
-            Ok(sa) => {
-                if let Some(result) = sa {
-                    info!(local = %result.local_addr, reflected = %result.reflected_addr, "NAT probe: reflected address");
-                    if let Ok(mut cache) = self.nat_reflection_cache.try_lock() {
-                        *cache = Some((Instant::now(), result.reflected_addr));
+        let attempt = self.nat_probe_attempts.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
+        let servers = if !self.nat_stun_servers.is_empty() {
+            self.nat_stun_servers.clone()
+        } else if let Some(s) = &self.nat_stun {
+            vec![s.clone()]
+        } else {
+            vec!["stun.l.google.com:19302".to_string()]
+        };
+
+        for stun_addr in servers {
+            match stun_probe_dual(&stun_addr).await {
+                Ok(res) => {
+                    let picked: Option<StunProbeResult> = match family {
+                        IpFamily::V4 => res.v4,
+                        IpFamily::V6 => res.v6,
+                    };
+                    if let Some(result) = picked {
+                        info!(local = %result.local_addr, reflected = %result.reflected_addr, family = ?family, stun = %stun_addr, "NAT probe: reflected address");
+                        self.nat_probe_attempts.store(0, std::sync::atomic::Ordering::Relaxed);
+                        if let Ok(mut cache) = self.nat_reflection_cache.try_lock() {
+                            let slot = match family {
+                                IpFamily::V4 => &mut cache.v4,
+                                IpFamily::V6 => &mut cache.v6,
+                            };
+                            *slot = Some((Instant::now(), result.reflected_addr));
+                        }
+                        return Some(result.reflected_addr);
                     }
-                    Some(result.reflected_addr)
-                } else {
-                    None
+                }
+                Err(e) => {
+                    warn!(error = %e, stun = %stun_addr, attempt = attempt + 1, "NAT probe failed, trying next server");
                 }
             }
-            Err(e) => {
-                warn!(error = %e, "NAT probe failed");
-                None
-            }
         }
+        let backoff = Duration::from_secs(60 * 2u64.pow((attempt as u32).min(6)));
+        *self.stun_backoff_until.write().await = Some(Instant::now() + backoff);
+        None
     }
 }
 
@@ -158,98 +190,3 @@ async fn fetch_public_ipv4_once(url: &str) -> Result<Option<Ipv4Addr>> {
     let ip = text.trim().parse().ok();
     Ok(ip)
 }
-
-async fn fetch_stun_binding(stun_addr: &str) -> Result<Option<StunProbeResult>> {
-    use rand::RngCore;
-    use tokio::net::UdpSocket;
-
-    let socket = UdpSocket::bind("0.0.0.0:0")
-        .await
-        .map_err(|e| ProxyError::Proxy(format!("STUN bind failed: {e}")))?;
-    socket
-        .connect(stun_addr)
-        .await
-        .map_err(|e| ProxyError::Proxy(format!("STUN connect failed: {e}")))?;
-
-    // Build minimal Binding Request.
-    let mut req = vec![0u8; 20];
-    req[0..2].copy_from_slice(&0x0001u16.to_be_bytes()); // Binding Request
-    req[2..4].copy_from_slice(&0u16.to_be_bytes()); // length
-    req[4..8].copy_from_slice(&0x2112A442u32.to_be_bytes()); // magic cookie
-    rand::rng().fill_bytes(&mut req[8..20]);
-
-    socket
-        .send(&req)
-        .await
-        .map_err(|e| ProxyError::Proxy(format!("STUN send failed: {e}")))?;
-
-    let mut buf = [0u8; 128];
-    let n = socket
-        .recv(&mut buf)
-        .await
-        .map_err(|e| ProxyError::Proxy(format!("STUN recv failed: {e}")))?;
-    if n < 20 {
-        return Ok(None);
-    }
-
-    // Parse attributes.
-    let mut idx = 20;
-    while idx + 4 <= n {
-        let atype = u16::from_be_bytes(buf[idx..idx + 2].try_into().unwrap());
-        let alen = u16::from_be_bytes(buf[idx + 2..idx + 4].try_into().unwrap()) as usize;
-        idx += 4;
-        if idx + alen > n {
-            break;
-        }
-        match atype {
-            0x0020 /* XOR-MAPPED-ADDRESS */ | 0x0001 /* MAPPED-ADDRESS */ => {
-                if alen < 8 {
-                    break;
-                }
-                let family = buf[idx + 1];
-                if family != 0x01 {
-                    // only IPv4 supported here
-                    break;
-                }
-                let port_bytes = [buf[idx + 2], buf[idx + 3]];
-                let ip_bytes = [buf[idx + 4], buf[idx + 5], buf[idx + 6], buf[idx + 7]];
-
-                let (port, ip) = if atype == 0x0020 {
-                    let magic = 0x2112A442u32.to_be_bytes();
-                    let port = u16::from_be_bytes(port_bytes) ^ ((magic[0] as u16) << 8 | magic[1] as u16);
-                    let ip = [
-                        ip_bytes[0] ^ magic[0],
-                        ip_bytes[1] ^ magic[1],
-                        ip_bytes[2] ^ magic[2],
-                        ip_bytes[3] ^ magic[3],
-                    ];
-                    (port, ip)
-                } else {
-                    (u16::from_be_bytes(port_bytes), ip_bytes)
-                };
-                let reflected = std::net::SocketAddr::new(
-                    IpAddr::V4(Ipv4Addr::new(ip[0], ip[1], ip[2], ip[3])),
-                    port,
-                );
-                let local_addr = socket.local_addr().map_err(|e| {
-                    ProxyError::Proxy(format!("STUN local_addr failed: {e}"))
-                })?;
-                return Ok(Some(StunProbeResult {
-                    local_addr,
-                    reflected_addr: reflected,
-                }));
-            }
-            _ => {}
-        }
-        idx += (alen + 3) & !3; // 4-byte alignment
-    }
-
-    Ok(None)
-}
-
-fn is_privateish(ip: IpAddr) -> bool {
-    match ip {
-        IpAddr::V4(v4) => v4.is_private() || v4.is_link_local(),
-        IpAddr::V6(v6) => v6.is_unique_local(),
-    }
-}

src/transport/middle_proxy/reader.rs

@@ -6,7 +6,7 @@ use std::time::Instant;
 use bytes::{Bytes, BytesMut};
 use tokio::io::AsyncReadExt;
 use tokio::net::TcpStream;
-use tokio::sync::Mutex;
+use tokio::sync::{Mutex, mpsc};
 use tokio_util::sync::CancellationToken;
 use tracing::{debug, trace, warn};
 
@@ -14,7 +14,7 @@ use crate::crypto::{AesCbc, crc32};
 use crate::error::{ProxyError, Result};
 use crate::protocol::constants::*;
 
-use super::codec::RpcWriter;
+use super::codec::WriterCommand;
 use super::{ConnRegistry, MeResponse};
 
 pub(crate) async fn reader_loop(
@@ -24,7 +24,7 @@ pub(crate) async fn reader_loop(
     reg: Arc<ConnRegistry>,
     enc_leftover: BytesMut,
     mut dec: BytesMut,
-    writer: Arc<Mutex<RpcWriter>>,
+    tx: mpsc::Sender<WriterCommand>,
     ping_tracker: Arc<Mutex<HashMap<i64, (Instant, u64)>>>,
     rtt_stats: Arc<Mutex<HashMap<u64, (f64, f64)>>>,
     _writer_id: u64,
@@ -33,6 +33,8 @@ pub(crate) async fn reader_loop(
 ) -> Result<()> {
     let mut raw = enc_leftover;
     let mut expected_seq: i32 = 0;
+    let mut crc_errors = 0u32;
+    let mut seq_mismatch = 0u32;
 
     loop {
         let mut tmp = [0u8; 16_384];
@@ -80,12 +82,20 @@ pub(crate) async fn reader_loop(
             let ec = u32::from_le_bytes(frame[pe..pe + 4].try_into().unwrap());
             if crc32(&frame[..pe]) != ec {
                 warn!("CRC mismatch in data frame");
+                crc_errors += 1;
+                if crc_errors > 3 {
+                    return Err(ProxyError::Proxy("Too many CRC mismatches".into()));
+                }
                 continue;
             }
 
             let seq_no = i32::from_le_bytes(frame[4..8].try_into().unwrap());
             if seq_no != expected_seq {
                 warn!(seq_no, expected = expected_seq, "ME RPC seq mismatch");
+                seq_mismatch += 1;
+                if seq_mismatch > 10 {
+                    return Err(ProxyError::Proxy("Too many seq mismatches".into()));
+                }
                 expected_seq = seq_no.wrapping_add(1);
             } else {
                 expected_seq = expected_seq.wrapping_add(1);
@@ -108,7 +118,7 @@ pub(crate) async fn reader_loop(
                 let routed = reg.route(cid, MeResponse::Data { flags, data }).await;
                 if !routed {
                     reg.unregister(cid).await;
-                    send_close_conn(&writer, cid).await;
+                    send_close_conn(&tx, cid).await;
                 }
             } else if pt == RPC_SIMPLE_ACK_U32 && body.len() >= 12 {
                 let cid = u64::from_le_bytes(body[0..8].try_into().unwrap());
@@ -118,7 +128,7 @@ pub(crate) async fn reader_loop(
                 let routed = reg.route(cid, MeResponse::Ack(cfm)).await;
                 if !routed {
                     reg.unregister(cid).await;
-                    send_close_conn(&writer, cid).await;
+                    send_close_conn(&tx, cid).await;
                 }
             } else if pt == RPC_CLOSE_EXT_U32 && body.len() >= 8 {
                 let cid = u64::from_le_bytes(body[0..8].try_into().unwrap());
@@ -136,8 +146,8 @@ pub(crate) async fn reader_loop(
                 let mut pong = Vec::with_capacity(12);
                 pong.extend_from_slice(&RPC_PONG_U32.to_le_bytes());
                 pong.extend_from_slice(&ping_id.to_le_bytes());
-                if let Err(e) = writer.lock().await.send(&pong).await {
-                    warn!(error = %e, "PONG send failed");
+                if tx.send(WriterCommand::DataAndFlush(pong)).await.is_err() {
+                    warn!("PONG send failed");
                     break;
                 }
             } else if pt == RPC_PONG_U32 && body.len() >= 8 {
@@ -152,6 +162,9 @@ pub(crate) async fn reader_loop(
                     entry.1 = entry.1 * 0.8 + rtt * 0.2;
                     if rtt < entry.0 {
                         entry.0 = rtt;
+                    } else {
+                        // allow slow baseline drift upward to avoid stale minimum
+                        entry.0 = entry.0 * 0.99 + rtt * 0.01;
                     }
                     let degraded_now = entry.1 > entry.0 * 2.0;
                     degraded.store(degraded_now, Ordering::Relaxed);
@@ -168,12 +181,10 @@ pub(crate) async fn reader_loop(
     }
 }
 
-async fn send_close_conn(writer: &Arc<Mutex<RpcWriter>>, conn_id: u64) {
+async fn send_close_conn(tx: &mpsc::Sender<WriterCommand>, conn_id: u64) {
     let mut p = Vec::with_capacity(12);
     p.extend_from_slice(&RPC_CLOSE_CONN_U32.to_le_bytes());
     p.extend_from_slice(&conn_id.to_le_bytes());
 
-    if let Err(e) = writer.lock().await.send(&p).await {
-        debug!(conn_id, error = %e, "Failed to send RPC_CLOSE_CONN");
-    }
+    let _ = tx.send(WriterCommand::DataAndFlush(p)).await;
 }

src/transport/middle_proxy/registry.rs

@@ -1,11 +1,11 @@
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::net::SocketAddr;
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::Arc;
 
 use tokio::sync::{mpsc, Mutex, RwLock};
 
-use super::codec::RpcWriter;
+use super::codec::WriterCommand;
 use super::MeResponse;
 
 #[derive(Clone)]
@@ -25,15 +25,31 @@ pub struct BoundConn {
 #[derive(Clone)]
 pub struct ConnWriter {
     pub writer_id: u64,
-    pub writer: Arc<Mutex<RpcWriter>>,
+    pub tx: mpsc::Sender<WriterCommand>,
+}
+
+struct RegistryInner {
+    map: HashMap<u64, mpsc::Sender<MeResponse>>,
+    writers: HashMap<u64, mpsc::Sender<WriterCommand>>,
+    writer_for_conn: HashMap<u64, u64>,
+    conns_for_writer: HashMap<u64, HashSet<u64>>,
+    meta: HashMap<u64, ConnMeta>,
+}
+
+impl RegistryInner {
+    fn new() -> Self {
+        Self {
+            map: HashMap::new(),
+            writers: HashMap::new(),
+            writer_for_conn: HashMap::new(),
+            conns_for_writer: HashMap::new(),
+            meta: HashMap::new(),
+        }
+    }
 }
 
 pub struct ConnRegistry {
-    map: RwLock<HashMap<u64, mpsc::Sender<MeResponse>>>,
-    writers: RwLock<HashMap<u64, Arc<Mutex<RpcWriter>>>>,
-    writer_for_conn: RwLock<HashMap<u64, u64>>,
-    conns_for_writer: RwLock<HashMap<u64, Vec<u64>>>,
-    meta: RwLock<HashMap<u64, ConnMeta>>,
+    inner: RwLock<RegistryInner>,
     next_id: AtomicU64,
 }
 
@@ -41,11 +57,7 @@ impl ConnRegistry {
     pub fn new() -> Self {
         let start = rand::random::<u64>() | 1;
         Self {
-            map: RwLock::new(HashMap::new()),
-            writers: RwLock::new(HashMap::new()),
-            writer_for_conn: RwLock::new(HashMap::new()),
-            conns_for_writer: RwLock::new(HashMap::new()),
-            meta: RwLock::new(HashMap::new()),
+            inner: RwLock::new(RegistryInner::new()),
             next_id: AtomicU64::new(start),
         }
     }
@@ -53,23 +65,27 @@ impl ConnRegistry {
     pub async fn register(&self) -> (u64, mpsc::Receiver<MeResponse>) {
         let id = self.next_id.fetch_add(1, Ordering::Relaxed);
         let (tx, rx) = mpsc::channel(1024);
-        self.map.write().await.insert(id, tx);
+        self.inner.write().await.map.insert(id, tx);
         (id, rx)
     }
 
-    pub async fn unregister(&self, id: u64) {
-        self.map.write().await.remove(&id);
-        self.meta.write().await.remove(&id);
-        if let Some(writer_id) = self.writer_for_conn.write().await.remove(&id) {
-            if let Some(list) = self.conns_for_writer.write().await.get_mut(&writer_id) {
-                list.retain(|c| *c != id);
+    /// Unregister connection, returning associated writer_id if any.
+    pub async fn unregister(&self, id: u64) -> Option<u64> {
+        let mut inner = self.inner.write().await;
+        inner.map.remove(&id);
+        inner.meta.remove(&id);
+        if let Some(writer_id) = inner.writer_for_conn.remove(&id) {
+            if let Some(set) = inner.conns_for_writer.get_mut(&writer_id) {
+                set.remove(&id);
             }
+            return Some(writer_id);
         }
+        None
     }
 
     pub async fn route(&self, id: u64, resp: MeResponse) -> bool {
-        let m = self.map.read().await;
-        if let Some(tx) = m.get(&id) {
+        let inner = self.inner.read().await;
+        if let Some(tx) = inner.map.get(&id) {
             tx.try_send(resp).is_ok()
         } else {
             false
@@ -80,43 +96,41 @@ impl ConnRegistry {
         &self,
         conn_id: u64,
         writer_id: u64,
-        writer: Arc<Mutex<RpcWriter>>,
+        tx: mpsc::Sender<WriterCommand>,
         meta: ConnMeta,
     ) {
-        self.meta.write().await.entry(conn_id).or_insert(meta);
-        self.writer_for_conn.write().await.insert(conn_id, writer_id);
-        self.writers.write().await.entry(writer_id).or_insert_with(|| writer.clone());
-        self.conns_for_writer
-            .write()
-            .await
+        let mut inner = self.inner.write().await;
+        inner.meta.entry(conn_id).or_insert(meta);
+        inner.writer_for_conn.insert(conn_id, writer_id);
+        inner.writers.entry(writer_id).or_insert_with(|| tx.clone());
+        inner
+            .conns_for_writer
             .entry(writer_id)
-            .or_insert_with(Vec::new)
-            .push(conn_id);
+            .or_insert_with(HashSet::new)
+            .insert(conn_id);
     }
 
     pub async fn get_writer(&self, conn_id: u64) -> Option<ConnWriter> {
-        let writer_id = {
-            let guard = self.writer_for_conn.read().await;
-            guard.get(&conn_id).cloned()
-        }?;
-        let writer = {
-            let guard = self.writers.read().await;
-            guard.get(&writer_id).cloned()
-        }?;
-        Some(ConnWriter { writer_id, writer })
+        let inner = self.inner.read().await;
+        let writer_id = inner.writer_for_conn.get(&conn_id).cloned()?;
+        let writer = inner.writers.get(&writer_id).cloned()?;
+        Some(ConnWriter { writer_id, tx: writer })
     }
 
     pub async fn writer_lost(&self, writer_id: u64) -> Vec<BoundConn> {
-        self.writers.write().await.remove(&writer_id);
-        let conns = self.conns_for_writer.write().await.remove(&writer_id).unwrap_or_default();
+        let mut inner = self.inner.write().await;
+        inner.writers.remove(&writer_id);
+        let conns = inner
+            .conns_for_writer
+            .remove(&writer_id)
+            .unwrap_or_default()
+            .into_iter()
+            .collect::<Vec<_>>();
 
         let mut out = Vec::new();
-        let mut writer_for_conn = self.writer_for_conn.write().await;
-        let meta = self.meta.read().await;
-
         for conn_id in conns {
-            writer_for_conn.remove(&conn_id);
-            if let Some(m) = meta.get(&conn_id) {
+            inner.writer_for_conn.remove(&conn_id);
+            if let Some(m) = inner.meta.get(&conn_id) {
                 out.push(BoundConn {
                     conn_id,
                     meta: m.clone(),
@@ -127,7 +141,16 @@ impl ConnRegistry {
     }
 
     pub async fn get_meta(&self, conn_id: u64) -> Option<ConnMeta> {
-        let guard = self.meta.read().await;
-        guard.get(&conn_id).cloned()
+        let inner = self.inner.read().await;
+        inner.meta.get(&conn_id).cloned()
+    }
+
+    pub async fn is_writer_empty(&self, writer_id: u64) -> bool {
+        let inner = self.inner.read().await;
+        inner
+            .conns_for_writer
+            .get(&writer_id)
+            .map(|s| s.is_empty())
+            .unwrap_or(true)
     }
 }

src/transport/middle_proxy/rotation.rs

@@ -1,4 +1,5 @@
 use std::sync::Arc;
+use std::sync::atomic::Ordering;
 use std::time::Duration;
 
 use tracing::{info, warn};
@@ -15,7 +16,12 @@ pub async fn me_rotation_task(pool: Arc<MePool>, rng: Arc<SecureRandom>, interva
 
         let candidate = {
             let ws = pool.writers.read().await;
-            ws.get(0).cloned()
+            if ws.is_empty() {
+                None
+            } else {
+                let idx = (pool.rr.load(std::sync::atomic::Ordering::Relaxed) as usize) % ws.len();
+                ws.get(idx).cloned()
+            }
         };
 
         let Some(w) = candidate else {
@@ -25,8 +31,17 @@ pub async fn me_rotation_task(pool: Arc<MePool>, rng: Arc<SecureRandom>, interva
         info!(addr = %w.addr, writer_id = w.id, "Rotating ME connection");
         match pool.connect_one(w.addr, rng.as_ref()).await {
             Ok(()) => {
-                // Remove old writer after new one is up.
-                pool.remove_writer_and_reroute(w.id).await;
+                tokio::time::sleep(Duration::from_secs(2)).await;
+                let ws = pool.writers.read().await;
+                let new_alive = ws.iter().any(|nw|
+                    nw.id != w.id && nw.addr == w.addr && !nw.degraded.load(Ordering::Relaxed) && !nw.draining.load(Ordering::Relaxed)
+                );
+                drop(ws);
+                if new_alive {
+                    pool.mark_writer_draining(w.id).await;
+                } else {
+                    warn!(addr = %w.addr, writer_id = w.id, "New writer died, keeping old");
+                }
             }
             Err(e) => {
                 warn!(addr = %w.addr, writer_id = w.id, error = %e, "ME rotation connect failed");
@@ -34,4 +49,3 @@ pub async fn me_rotation_task(pool: Arc<MePool>, rng: Arc<SecureRandom>, interva
         }
     }
 }
-

src/transport/middle_proxy/send.rs

@@ -3,15 +3,15 @@ use std::sync::Arc;
 use std::sync::atomic::Ordering;
 use std::time::Duration;
 
-use tokio::sync::Mutex;
 use tracing::{debug, warn};
 
 use crate::error::{ProxyError, Result};
+use crate::network::IpFamily;
 use crate::protocol::constants::RPC_CLOSE_EXT_U32;
 
 use super::MePool;
+use super::codec::WriterCommand;
 use super::wire::build_proxy_req_payload;
-use crate::crypto::SecureRandom;
 use rand::seq::SliceRandom;
 use super::registry::ConnMeta;
 
@@ -44,19 +44,16 @@ impl MePool {
         loop {
             if let Some(current) = self.registry.get_writer(conn_id).await {
                 let send_res = {
-                    if let Ok(mut guard) = current.writer.try_lock() {
-                        let r = guard.send(&payload).await;
-                        drop(guard);
-                        r
-                    } else {
-                        current.writer.lock().await.send(&payload).await
-                    }
+                    current
+                        .tx
+                        .send(WriterCommand::Data(payload.clone()))
+                        .await
                 };
                 match send_res {
                     Ok(()) => return Ok(()),
-                    Err(e) => {
-                        warn!(error = %e, writer_id = current.writer_id, "ME write failed");
-                        self.remove_writer_and_reroute(current.writer_id).await;
+                    Err(_) => {
+                        warn!(writer_id = current.writer_id, "ME writer channel closed");
+                        self.remove_writer_and_close_clients(current.writer_id).await;
                         continue;
                     }
                 }
@@ -65,7 +62,26 @@ impl MePool {
             let mut writers_snapshot = {
                 let ws = self.writers.read().await;
                 if ws.is_empty() {
-                    return Err(ProxyError::Proxy("All ME connections dead".into()));
+                    drop(ws);
+                    for family in self.family_order() {
+                        let map = match family {
+                            IpFamily::V4 => self.proxy_map_v4.read().await.clone(),
+                            IpFamily::V6 => self.proxy_map_v6.read().await.clone(),
+                        };
+                        for (_dc, addrs) in map.iter() {
+                            for (ip, port) in addrs {
+                                let addr = SocketAddr::new(*ip, *port);
+                                if self.connect_one(addr, self.rng.as_ref()).await.is_ok() {
+                                    self.writer_available.notify_waiters();
+                                    break;
+                                }
+                            }
+                        }
+                    }
+                    if tokio::time::timeout(Duration::from_secs(3), self.writer_available.notified()).await.is_err() {
+                        return Err(ProxyError::Proxy("All ME connections dead (waited 3s)".into()));
+                    }
+                    continue;
                 }
                 ws.clone()
             };
@@ -77,22 +93,30 @@ impl MePool {
                     return Err(ProxyError::Proxy("No ME writers available for target DC".into()));
                 }
                 emergency_attempts += 1;
-                let map = self.proxy_map_v4.read().await;
-                if let Some(addrs) = map.get(&(target_dc as i32)) {
-                    let mut shuffled = addrs.clone();
-                    shuffled.shuffle(&mut rand::rng());
-                    drop(map);
-                    for (ip, port) in shuffled {
-                        let addr = SocketAddr::new(ip, port);
-                        if self.connect_one(addr, &SecureRandom::new()).await.is_ok() {
+                for family in self.family_order() {
+                    let map_guard = match family {
+                        IpFamily::V4 => self.proxy_map_v4.read().await,
+                        IpFamily::V6 => self.proxy_map_v6.read().await,
+                    };
+                    if let Some(addrs) = map_guard.get(&(target_dc as i32)) {
+                        let mut shuffled = addrs.clone();
+                        shuffled.shuffle(&mut rand::rng());
+                        drop(map_guard);
+                        for (ip, port) in shuffled {
+                            let addr = SocketAddr::new(ip, port);
+                            if self.connect_one(addr, self.rng.as_ref()).await.is_ok() {
+                                break;
+                            }
+                        }
+                        tokio::time::sleep(Duration::from_millis(100 * emergency_attempts)).await;
+                        let ws2 = self.writers.read().await;
+                        writers_snapshot = ws2.clone();
+                        drop(ws2);
+                        candidate_indices = self.candidate_indices_for_dc(&writers_snapshot, target_dc).await;
+                        if !candidate_indices.is_empty() {
                             break;
                         }
                     }
-                    tokio::time::sleep(Duration::from_millis(100 * emergency_attempts)).await;
-                    let ws2 = self.writers.read().await;
-                    writers_snapshot = ws2.clone();
-                    drop(ws2);
-                    candidate_indices = self.candidate_indices_for_dc(&writers_snapshot, target_dc).await;
                 }
                 if candidate_indices.is_empty() {
                     return Err(ProxyError::Proxy("No ME writers available for target DC".into()));
@@ -100,11 +124,10 @@ impl MePool {
             }
 
             candidate_indices.sort_by_key(|idx| {
-                writers_snapshot[*idx]
-                    .degraded
-                    .load(Ordering::Relaxed)
-                    .then_some(1usize)
-                    .unwrap_or(0)
+                let w = &writers_snapshot[*idx];
+                let degraded = w.degraded.load(Ordering::Relaxed);
+                let draining = w.draining.load(Ordering::Relaxed);
+                (draining as usize, degraded as usize)
             });
 
             let start = self.rr.fetch_add(1, Ordering::Relaxed) as usize % candidate_indices.len();
@@ -112,36 +135,35 @@ impl MePool {
             for offset in 0..candidate_indices.len() {
                 let idx = candidate_indices[(start + offset) % candidate_indices.len()];
                 let w = &writers_snapshot[idx];
-                if let Ok(mut guard) = w.writer.try_lock() {
-                    let send_res = guard.send(&payload).await;
-                    drop(guard);
-                    match send_res {
-                        Ok(()) => {
-                            self.registry
-                                .bind_writer(conn_id, w.id, w.writer.clone(), meta.clone())
-                                .await;
-                            return Ok(());
-                        }
-                        Err(e) => {
-                            warn!(error = %e, writer_id = w.id, "ME write failed");
-                            self.remove_writer_and_reroute(w.id).await;
-                            continue;
-                        }
-                    }
+                if w.draining.load(Ordering::Relaxed) {
+                    continue;
+                }
+                if w.tx.send(WriterCommand::Data(payload.clone())).await.is_ok() {
+                    self.registry
+                        .bind_writer(conn_id, w.id, w.tx.clone(), meta.clone())
+                        .await;
+                    return Ok(());
+                } else {
+                    warn!(writer_id = w.id, "ME writer channel closed");
+                    self.remove_writer_and_close_clients(w.id).await;
+                    continue;
                 }
             }
 
             let w = writers_snapshot[candidate_indices[start]].clone();
-            match w.writer.lock().await.send(&payload).await {
+            if w.draining.load(Ordering::Relaxed) {
+                continue;
+            }
+            match w.tx.send(WriterCommand::Data(payload.clone())).await {
                 Ok(()) => {
                     self.registry
-                        .bind_writer(conn_id, w.id, w.writer.clone(), meta.clone())
+                        .bind_writer(conn_id, w.id, w.tx.clone(), meta.clone())
                         .await;
                     return Ok(());
                 }
-                Err(e) => {
-                    warn!(error = %e, writer_id = w.id, "ME write failed (blocking)");
-                    self.remove_writer_and_reroute(w.id).await;
+                Err(_) => {
+                    warn!(writer_id = w.id, "ME writer channel closed (blocking)");
+                    self.remove_writer_and_close_clients(w.id).await;
                 }
             }
         }
@@ -152,9 +174,9 @@ impl MePool {
             let mut p = Vec::with_capacity(12);
             p.extend_from_slice(&RPC_CLOSE_EXT_U32.to_le_bytes());
             p.extend_from_slice(&conn_id.to_le_bytes());
-            if let Err(e) = w.writer.lock().await.send(&p).await {
-                debug!(error = %e, "ME close write failed");
-                self.remove_writer_and_reroute(w.writer_id).await;
+            if w.tx.send(WriterCommand::DataAndFlush(p)).await.is_err() {
+                debug!("ME close write failed");
+                self.remove_writer_and_close_clients(w.writer_id).await;
             }
         } else {
             debug!(conn_id, "ME close skipped (writer missing)");
@@ -165,7 +187,7 @@ impl MePool {
     }
 
     pub fn connection_count(&self) -> usize {
-        self.writers.try_read().map(|w| w.len()).unwrap_or(0)
+        self.conn_count.load(Ordering::Relaxed)
     }
     
     pub(super) async fn candidate_indices_for_dc(
@@ -173,46 +195,65 @@ impl MePool {
         writers: &[super::pool::MeWriter],
         target_dc: i16,
     ) -> Vec<usize> {
-        let mut preferred = Vec::<SocketAddr>::new();
         let key = target_dc as i32;
-        let map = self.proxy_map_v4.read().await;
+        let mut preferred = Vec::<SocketAddr>::new();
 
-        if let Some(v) = map.get(&key) {
-            preferred.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
-        }
-        if preferred.is_empty() {
-            let abs = key.abs();
-            if let Some(v) = map.get(&abs) {
+        for family in self.family_order() {
+            let map_guard = match family {
+                IpFamily::V4 => self.proxy_map_v4.read().await,
+                IpFamily::V6 => self.proxy_map_v6.read().await,
+            };
+
+            if let Some(v) = map_guard.get(&key) {
                 preferred.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
             }
-        }
-        if preferred.is_empty() {
-            let abs = key.abs();
-            if let Some(v) = map.get(&-abs) {
-                preferred.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
-            }
-        }
-        if preferred.is_empty() {
-            let def = self.default_dc.load(Ordering::Relaxed);
-            if def != 0 {
-                if let Some(v) = map.get(&def) {
+            if preferred.is_empty() {
+                let abs = key.abs();
+                if let Some(v) = map_guard.get(&abs) {
                     preferred.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
                 }
             }
+            if preferred.is_empty() {
+                let abs = key.abs();
+                if let Some(v) = map_guard.get(&-abs) {
+                    preferred.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
+                }
+            }
+            if preferred.is_empty() {
+                let def = self.default_dc.load(Ordering::Relaxed);
+                if def != 0 {
+                    if let Some(v) = map_guard.get(&def) {
+                        preferred.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
+                    }
+                }
+            }
+
+            drop(map_guard);
+
+            if !preferred.is_empty() && !self.decision.effective_multipath {
+                break;
+            }
         }
 
         if preferred.is_empty() {
-            return (0..writers.len()).collect();
+            return (0..writers.len())
+                .filter(|i| !writers[*i].draining.load(Ordering::Relaxed))
+                .collect();
         }
 
         let mut out = Vec::new();
         for (idx, w) in writers.iter().enumerate() {
+            if w.draining.load(Ordering::Relaxed) {
+                continue;
+            }
             if preferred.iter().any(|p| *p == w.addr) {
                 out.push(idx);
             }
         }
         if out.is_empty() {
-            return (0..writers.len()).collect();
+            return (0..writers.len())
+                .filter(|i| !writers[*i].draining.load(Ordering::Relaxed))
+                .collect();
         }
         out
     }

src/transport/upstream.rs

@@ -167,20 +167,44 @@ impl UpstreamManager {
     }
 
     /// Select upstream using latency-weighted random selection.
-    async fn select_upstream(&self, dc_idx: Option<i16>) -> Option<usize> {
+    async fn select_upstream(&self, dc_idx: Option<i16>, scope: Option<&str>) -> Option<usize> {
         let upstreams = self.upstreams.read().await;
         if upstreams.is_empty() {
             return None;
         }
-
-        let healthy: Vec<usize> = upstreams.iter()
+        // Scope filter:
+        //   If scope is set: only scoped and matched items
+        //   If scope is not set: only unscoped items
+        let filtered_upstreams : Vec<usize> = upstreams.iter()
             .enumerate()
-            .filter(|(_, u)| u.healthy)
+            .filter(|(_, u)| {
+                scope.map_or(
+                    u.config.scopes.is_empty(),
+                    |req_scope| {
+                        u.config.scopes
+                            .split(',')
+                            .map(str::trim)
+                            .any(|s| s == req_scope)
+                    }
+                )
+            })
             .map(|(i, _)| i)
             .collect();
 
+        // Healthy filter
+        let healthy: Vec<usize> = filtered_upstreams.iter()
+            .filter(|&&i| upstreams[i].healthy)
+            .copied()
+            .collect();
+
+        if filtered_upstreams.is_empty() {
+            warn!(scope = scope, "No upstreams available! Using first (direct?)");
+            return None;
+        }
+
         if healthy.is_empty() {
-            return Some(rand::rng().gen_range(0..upstreams.len()));
+            warn!(scope = scope, "No healthy upstreams available! Using random.");
+            return Some(filtered_upstreams[rand::rng().gen_range(0..filtered_upstreams.len())]);
         }
 
         if healthy.len() == 1 {
@@ -222,15 +246,20 @@ impl UpstreamManager {
     }
 
     /// Connect to target through a selected upstream.
-    pub async fn connect(&self, target: SocketAddr, dc_idx: Option<i16>) -> Result<TcpStream> {
-        let idx = self.select_upstream(dc_idx).await
+    pub async fn connect(&self, target: SocketAddr, dc_idx: Option<i16>, scope: Option<&str>) -> Result<TcpStream> {
+        let idx = self.select_upstream(dc_idx, scope).await
             .ok_or_else(|| ProxyError::Config("No upstreams available".to_string()))?;
 
-        let upstream = {
+        let mut upstream = {
             let guard = self.upstreams.read().await;
             guard[idx].config.clone()
         };
 
+        // Set scope for configuration copy
+        if let Some(s) = scope {
+            upstream.selected_scope = s.to_string();
+        }
+
         let start = Instant::now();
 
         match self.connect_via_upstream(&upstream, target).await {
@@ -313,8 +342,12 @@ impl UpstreamManager {
                 if let Some(e) = stream.take_error()? {
                     return Err(ProxyError::Io(e));
                 }
+                // replace socks user_id with config.selected_scope, if set
+                let scope: Option<&str> = Some(config.selected_scope.as_str())
+                    .filter(|s| !s.is_empty());
+                let _user_id: Option<&str> = scope.or(user_id.as_deref());
 
-                connect_socks4(&mut stream, target, user_id.as_deref()).await?;
+                connect_socks4(&mut stream, target, _user_id).await?;
                 Ok(stream)
             },
             UpstreamType::Socks5 { address, interface, username, password } => {
@@ -341,7 +374,14 @@ impl UpstreamManager {
                     return Err(ProxyError::Io(e));
                 }
 
-                connect_socks5(&mut stream, target, username.as_deref(), password.as_deref()).await?;
+                debug!(config = ?config, "Socks5 connection");
+                // replace socks user:pass with config.selected_scope, if set
+                let scope: Option<&str> = Some(config.selected_scope.as_str())
+                    .filter(|s| !s.is_empty());
+                let _username: Option<&str> = scope.or(username.as_deref());
+                let _password: Option<&str> = scope.or(password.as_deref());
+
+                connect_socks5(&mut stream, target, _username, _password).await?;
                 Ok(stream)
             },
         }
@@ -355,6 +395,8 @@ impl UpstreamManager {
         &self,
         prefer_ipv6: bool,
         dc_overrides: &HashMap<String, Vec<String>>,
+        ipv4_enabled: bool,
+        ipv6_enabled: bool,
     ) -> Vec<StartupPingResult> {
         let upstreams: Vec<(usize, UpstreamConfig)> = {
             let guard = self.upstreams.read().await;
@@ -374,85 +416,106 @@ impl UpstreamManager {
                 UpstreamType::Socks5 { address, .. } => format!("socks5://{}", address),
             };
 
-            let mut v6_results = Vec::new();
-            let mut v4_results = Vec::new();
+            let mut v6_results = Vec::with_capacity(NUM_DCS);
+            if ipv6_enabled {
+                for dc_zero_idx in 0..NUM_DCS {
+                    let dc_v6 = TG_DATACENTERS_V6[dc_zero_idx];
+                    let addr_v6 = SocketAddr::new(dc_v6, TG_DATACENTER_PORT);
 
-            // === Ping IPv6 first ===
-            for dc_zero_idx in 0..NUM_DCS {
-                let dc_v6 = TG_DATACENTERS_V6[dc_zero_idx];
-                let addr_v6 = SocketAddr::new(dc_v6, TG_DATACENTER_PORT);
+                    let result = tokio::time::timeout(
+                        Duration::from_secs(DC_PING_TIMEOUT_SECS),
+                        self.ping_single_dc(&upstream_config, addr_v6)
+                    ).await;
 
-                let result = tokio::time::timeout(
-                    Duration::from_secs(DC_PING_TIMEOUT_SECS),
-                    self.ping_single_dc(&upstream_config, addr_v6)
-                ).await;
-
-                let ping_result = match result {
-                    Ok(Ok(rtt_ms)) => {
-                        let mut guard = self.upstreams.write().await;
-                        if let Some(u) = guard.get_mut(*upstream_idx) {
-                            u.dc_latency[dc_zero_idx].update(rtt_ms);
+                    let ping_result = match result {
+                        Ok(Ok(rtt_ms)) => {
+                            let mut guard = self.upstreams.write().await;
+                            if let Some(u) = guard.get_mut(*upstream_idx) {
+                                u.dc_latency[dc_zero_idx].update(rtt_ms);
+                            }
+                            DcPingResult {
+                                dc_idx: dc_zero_idx + 1,
+                                dc_addr: addr_v6,
+                                rtt_ms: Some(rtt_ms),
+                                error: None,
+                            }
                         }
-                        DcPingResult {
+                        Ok(Err(e)) => DcPingResult {
                             dc_idx: dc_zero_idx + 1,
                             dc_addr: addr_v6,
-                            rtt_ms: Some(rtt_ms),
-                            error: None,
-                        }
-                    }
-                    Ok(Err(e)) => DcPingResult {
+                            rtt_ms: None,
+                            error: Some(e.to_string()),
+                        },
+                        Err(_) => DcPingResult {
+                            dc_idx: dc_zero_idx + 1,
+                            dc_addr: addr_v6,
+                            rtt_ms: None,
+                            error: Some("timeout".to_string()),
+                        },
+                    };
+                    v6_results.push(ping_result);
+                }
+            } else {
+                for dc_zero_idx in 0..NUM_DCS {
+                    let dc_v6 = TG_DATACENTERS_V6[dc_zero_idx];
+                    v6_results.push(DcPingResult {
                         dc_idx: dc_zero_idx + 1,
-                        dc_addr: addr_v6,
+                        dc_addr: SocketAddr::new(dc_v6, TG_DATACENTER_PORT),
                         rtt_ms: None,
-                        error: Some(e.to_string()),
-                    },
-                    Err(_) => DcPingResult {
-                        dc_idx: dc_zero_idx + 1,
-                        dc_addr: addr_v6,
-                        rtt_ms: None,
-                        error: Some("timeout".to_string()),
-                    },
-                };
-                v6_results.push(ping_result);
+                        error: Some("ipv6 disabled".to_string()),
+                    });
+                }
             }
 
-            // === Then ping IPv4 ===
-            for dc_zero_idx in 0..NUM_DCS {
-                let dc_v4 = TG_DATACENTERS_V4[dc_zero_idx];
-                let addr_v4 = SocketAddr::new(dc_v4, TG_DATACENTER_PORT);
+            let mut v4_results = Vec::with_capacity(NUM_DCS);
+            if ipv4_enabled {
+                for dc_zero_idx in 0..NUM_DCS {
+                    let dc_v4 = TG_DATACENTERS_V4[dc_zero_idx];
+                    let addr_v4 = SocketAddr::new(dc_v4, TG_DATACENTER_PORT);
 
-                let result = tokio::time::timeout(
-                    Duration::from_secs(DC_PING_TIMEOUT_SECS),
-                    self.ping_single_dc(&upstream_config, addr_v4)
-                ).await;
+                    let result = tokio::time::timeout(
+                        Duration::from_secs(DC_PING_TIMEOUT_SECS),
+                        self.ping_single_dc(&upstream_config, addr_v4)
+                    ).await;
 
-                let ping_result = match result {
-                    Ok(Ok(rtt_ms)) => {
-                        let mut guard = self.upstreams.write().await;
-                        if let Some(u) = guard.get_mut(*upstream_idx) {
-                            u.dc_latency[dc_zero_idx].update(rtt_ms);
+                    let ping_result = match result {
+                        Ok(Ok(rtt_ms)) => {
+                            let mut guard = self.upstreams.write().await;
+                            if let Some(u) = guard.get_mut(*upstream_idx) {
+                                u.dc_latency[dc_zero_idx].update(rtt_ms);
+                            }
+                            DcPingResult {
+                                dc_idx: dc_zero_idx + 1,
+                                dc_addr: addr_v4,
+                                rtt_ms: Some(rtt_ms),
+                                error: None,
+                            }
                         }
-                        DcPingResult {
+                        Ok(Err(e)) => DcPingResult {
                             dc_idx: dc_zero_idx + 1,
                             dc_addr: addr_v4,
-                            rtt_ms: Some(rtt_ms),
-                            error: None,
-                        }
-                    }
-                    Ok(Err(e)) => DcPingResult {
+                            rtt_ms: None,
+                            error: Some(e.to_string()),
+                        },
+                        Err(_) => DcPingResult {
+                            dc_idx: dc_zero_idx + 1,
+                            dc_addr: addr_v4,
+                            rtt_ms: None,
+                            error: Some("timeout".to_string()),
+                        },
+                    };
+                    v4_results.push(ping_result);
+                }
+            } else {
+                for dc_zero_idx in 0..NUM_DCS {
+                    let dc_v4 = TG_DATACENTERS_V4[dc_zero_idx];
+                    v4_results.push(DcPingResult {
                         dc_idx: dc_zero_idx + 1,
-                        dc_addr: addr_v4,
+                        dc_addr: SocketAddr::new(dc_v4, TG_DATACENTER_PORT),
                         rtt_ms: None,
-                        error: Some(e.to_string()),
-                    },
-                    Err(_) => DcPingResult {
-                        dc_idx: dc_zero_idx + 1,
-                        dc_addr: addr_v4,
-                        rtt_ms: None,
-                        error: Some("timeout".to_string()),
-                    },
-                };
-                v4_results.push(ping_result);
+                        error: Some("ipv4 disabled".to_string()),
+                    });
+                }
             }
 
             // === Ping DC overrides (v4/v6) ===
@@ -470,6 +533,9 @@ impl UpstreamManager {
                     match addr_str.parse::<SocketAddr>() {
                         Ok(addr) => {
                             let is_v6 = addr.is_ipv6();
+                            if (is_v6 && !ipv6_enabled) || (!is_v6 && !ipv4_enabled) {
+                                continue;
+                            }
                             let result = tokio::time::timeout(
                                 Duration::from_secs(DC_PING_TIMEOUT_SECS),
                                 self.ping_single_dc(&upstream_config, addr)
@@ -551,7 +617,7 @@ impl UpstreamManager {
 
     /// Background health check: rotates through DCs, 30s interval.
     /// Uses preferred IP version based on config.
-    pub async fn run_health_checks(&self, prefer_ipv6: bool) {
+    pub async fn run_health_checks(&self, prefer_ipv6: bool, ipv4_enabled: bool, ipv6_enabled: bool) {
         let mut dc_rotation = 0usize;
 
         loop {
@@ -560,16 +626,24 @@ impl UpstreamManager {
             let dc_zero_idx = dc_rotation % NUM_DCS;
             dc_rotation += 1;
 
-            let dc_addr = if prefer_ipv6 {
-                SocketAddr::new(TG_DATACENTERS_V6[dc_zero_idx], TG_DATACENTER_PORT)
+            let primary_v6 = SocketAddr::new(TG_DATACENTERS_V6[dc_zero_idx], TG_DATACENTER_PORT);
+            let primary_v4 = SocketAddr::new(TG_DATACENTERS_V4[dc_zero_idx], TG_DATACENTER_PORT);
+            let dc_addr = if prefer_ipv6 && ipv6_enabled {
+                primary_v6
+            } else if ipv4_enabled {
+                primary_v4
+            } else if ipv6_enabled {
+                primary_v6
             } else {
-                SocketAddr::new(TG_DATACENTERS_V4[dc_zero_idx], TG_DATACENTER_PORT)
+                continue;
             };
 
-            let fallback_addr = if prefer_ipv6 {
-                SocketAddr::new(TG_DATACENTERS_V4[dc_zero_idx], TG_DATACENTER_PORT)
+            let fallback_addr = if dc_addr.is_ipv6() && ipv4_enabled {
+                Some(primary_v4)
+            } else if dc_addr.is_ipv4() && ipv6_enabled {
+                Some(primary_v6)
             } else {
-                SocketAddr::new(TG_DATACENTERS_V6[dc_zero_idx], TG_DATACENTER_PORT)
+                None
             };
 
             let count = self.upstreams.read().await.len();
@@ -608,48 +682,60 @@ impl UpstreamManager {
                         // Try fallback
                         debug!(dc = dc_zero_idx + 1, "Health check failed, trying fallback");
 
-                        let start2 = Instant::now();
-                        let result2 = tokio::time::timeout(
-                            Duration::from_secs(10),
-                            self.connect_via_upstream(&config, fallback_addr)
-                        ).await;
+                        if let Some(fallback_addr) = fallback_addr {
+                            let start2 = Instant::now();
+                            let result2 = tokio::time::timeout(
+                                Duration::from_secs(10),
+                                self.connect_via_upstream(&config, fallback_addr)
+                            ).await;
+
+                            let mut guard = self.upstreams.write().await;
+                            let u = &mut guard[i];
+
+                            match result2 {
+                                Ok(Ok(_stream)) => {
+                                    let rtt_ms = start2.elapsed().as_secs_f64() * 1000.0;
+                                    u.dc_latency[dc_zero_idx].update(rtt_ms);
+
+                                    if !u.healthy {
+                                        info!(
+                                            rtt = format!("{:.0} ms", rtt_ms),
+                                            dc = dc_zero_idx + 1,
+                                            "Upstream recovered (fallback)"
+                                        );
+                                    }
+                                    u.healthy = true;
+                                    u.fails = 0;
+                                }
+                                Ok(Err(e)) => {
+                                    u.fails += 1;
+                                    debug!(dc = dc_zero_idx + 1, fails = u.fails,
+                                        "Health check failed (both): {}", e);
+                                    if u.fails > 3 {
+                                        u.healthy = false;
+                                        warn!("Upstream unhealthy (fails)");
+                                    }
+                                }
+                                Err(_) => {
+                                    u.fails += 1;
+                                    debug!(dc = dc_zero_idx + 1, fails = u.fails,
+                                        "Health check timeout (both)");
+                                    if u.fails > 3 {
+                                        u.healthy = false;
+                                        warn!("Upstream unhealthy (timeout)");
+                                    }
+                                }
+                            }
+                            u.last_check = std::time::Instant::now();
+                            continue;
+                        }
 
                         let mut guard = self.upstreams.write().await;
                         let u = &mut guard[i];
-
-                        match result2 {
-                            Ok(Ok(_stream)) => {
-                                let rtt_ms = start2.elapsed().as_secs_f64() * 1000.0;
-                                u.dc_latency[dc_zero_idx].update(rtt_ms);
-
-                                if !u.healthy {
-                                    info!(
-                                        rtt = format!("{:.0} ms", rtt_ms),
-                                        dc = dc_zero_idx + 1,
-                                        "Upstream recovered (fallback)"
-                                    );
-                                }
-                                u.healthy = true;
-                                u.fails = 0;
-                            }
-                            Ok(Err(e)) => {
-                                u.fails += 1;
-                                debug!(dc = dc_zero_idx + 1, fails = u.fails,
-                                    "Health check failed (both): {}", e);
-                                if u.fails > 3 {
-                                    u.healthy = false;
-                                    warn!("Upstream unhealthy (fails)");
-                                }
-                            }
-                            Err(_) => {
-                                u.fails += 1;
-                                debug!(dc = dc_zero_idx + 1, fails = u.fails,
-                                    "Health check timeout (both)");
-                                if u.fails > 3 {
-                                    u.healthy = false;
-                                    warn!("Upstream unhealthy (timeout)");
-                                }
-                            }
+                        u.fails += 1;
+                        if u.fails > 3 {
+                            u.healthy = false;
+                            warn!("Upstream unhealthy (no fallback family)");
                         }
                         u.last_check = std::time::Instant::now();
                     }

tools/grafana-dashboard.json

@@ -0,0 +1,804 @@
+{
+  "apiVersion": "dashboard.grafana.app/v1beta1",
+  "kind": "Dashboard",
+  "metadata": {
+    "annotations": {
+      "grafana.app/folder": "afd9kjusw2jnkb",
+      "grafana.app/saved-from-ui": "Grafana v12.4.0-21693836646 (f059795f04)"
+    },
+    "labels": {},
+    "name": "pi9trh5",
+    "namespace": "default"
+  },
+  "spec": {
+    "annotations": {
+      "list": [
+        {
+          "builtIn": 1,
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${datasource}"
+          },
+          "enable": true,
+          "hide": true,
+          "iconColor": "rgba(0, 211, 255, 1)",
+          "name": "Annotations & Alerts",
+          "type": "dashboard"
+        }
+      ]
+    },
+    "editable": true,
+    "fiscalYearStartMonth": 0,
+    "graphTooltip": 0,
+    "links": [],
+    "panels": [
+      {
+        "collapsed": false,
+        "gridPos": {
+          "h": 1,
+          "w": 24,
+          "x": 0,
+          "y": 0
+        },
+        "id": 5,
+        "panels": [],
+        "title": "Common",
+        "type": "row"
+      },
+      {
+        "datasource": {
+          "type": "prometheus",
+          "uid": "${datasource}"
+        },
+        "fieldConfig": {
+          "defaults": {
+            "color": {
+              "mode": "thresholds"
+            },
+            "mappings": [],
+            "thresholds": {
+              "mode": "absolute",
+              "steps": [
+                {
+                  "color": "red",
+                  "value": 0
+                },
+                {
+                  "color": "green",
+                  "value": 300
+                }
+              ]
+            },
+            "unit": "s"
+          },
+          "overrides": []
+        },
+        "gridPos": {
+          "h": 8,
+          "w": 6,
+          "x": 0,
+          "y": 1
+        },
+        "id": 1,
+        "options": {
+          "colorMode": "value",
+          "graphMode": "area",
+          "justifyMode": "auto",
+          "orientation": "auto",
+          "percentChangeColorMode": "standard",
+          "reduceOptions": {
+            "calcs": [
+              "lastNotNull"
+            ],
+            "fields": "",
+            "values": false
+          },
+          "showPercentChange": false,
+          "textMode": "auto",
+          "wideLayout": true
+        },
+        "pluginVersion": "12.4.0-21693836646",
+        "targets": [
+          {
+            "datasource": {
+              "type": "prometheus",
+              "uid": "${datasource}"
+            },
+            "editorMode": "code",
+            "expr": "max(telemt_uptime_seconds) by (service)",
+            "format": "time_series",
+            "legendFormat": "__auto",
+            "range": true,
+            "refId": "A"
+          }
+        ],
+        "title": "uptime",
+        "type": "stat"
+      },
+      {
+        "datasource": {
+          "type": "prometheus",
+          "uid": "${datasource}"
+        },
+        "fieldConfig": {
+          "defaults": {
+            "color": {
+              "mode": "thresholds"
+            },
+            "mappings": [],
+            "thresholds": {
+              "mode": "absolute",
+              "steps": [
+                {
+                  "color": "green",
+                  "value": 0
+                },
+                {
+                  "color": "red",
+                  "value": 80
+                }
+              ]
+            },
+            "unit": "none"
+          },
+          "overrides": []
+        },
+        "gridPos": {
+          "h": 8,
+          "w": 6,
+          "x": 6,
+          "y": 1
+        },
+        "id": 2,
+        "options": {
+          "colorMode": "value",
+          "graphMode": "area",
+          "justifyMode": "auto",
+          "orientation": "auto",
+          "percentChangeColorMode": "standard",
+          "reduceOptions": {
+            "calcs": [
+              "lastNotNull"
+            ],
+            "fields": "",
+            "values": false
+          },
+          "showPercentChange": false,
+          "textMode": "auto",
+          "wideLayout": true
+        },
+        "pluginVersion": "12.4.0-21693836646",
+        "targets": [
+          {
+            "datasource": {
+              "type": "prometheus",
+              "uid": "${datasource}"
+            },
+            "editorMode": "code",
+            "expr": "max(telemt_connections_total) by (service)",
+            "format": "time_series",
+            "legendFormat": "__auto",
+            "range": true,
+            "refId": "A"
+          }
+        ],
+        "title": "connections_total",
+        "type": "stat"
+      },
+      {
+        "datasource": {
+          "type": "prometheus",
+          "uid": "${datasource}"
+        },
+        "fieldConfig": {
+          "defaults": {
+            "color": {
+              "mode": "thresholds"
+            },
+            "mappings": [],
+            "thresholds": {
+              "mode": "absolute",
+              "steps": [
+                {
+                  "color": "green",
+                  "value": 0
+                },
+                {
+                  "color": "red",
+                  "value": 80
+                }
+              ]
+            },
+            "unit": "none"
+          },
+          "overrides": []
+        },
+        "gridPos": {
+          "h": 8,
+          "w": 6,
+          "x": 12,
+          "y": 1
+        },
+        "id": 3,
+        "options": {
+          "colorMode": "value",
+          "graphMode": "area",
+          "justifyMode": "auto",
+          "orientation": "auto",
+          "percentChangeColorMode": "standard",
+          "reduceOptions": {
+            "calcs": [
+              "lastNotNull"
+            ],
+            "fields": "",
+            "values": false
+          },
+          "showPercentChange": false,
+          "textMode": "auto",
+          "wideLayout": true
+        },
+        "pluginVersion": "12.4.0-21693836646",
+        "targets": [
+          {
+            "datasource": {
+              "type": "prometheus",
+              "uid": "${datasource}"
+            },
+            "editorMode": "code",
+            "expr": "max(telemt_connections_bad_total) by (service)",
+            "format": "time_series",
+            "legendFormat": "__auto",
+            "range": true,
+            "refId": "A"
+          }
+        ],
+        "title": "connections_bad",
+        "type": "stat"
+      },
+      {
+        "datasource": {
+          "type": "prometheus",
+          "uid": "${datasource}"
+        },
+        "fieldConfig": {
+          "defaults": {
+            "color": {
+              "mode": "thresholds"
+            },
+            "mappings": [],
+            "thresholds": {
+              "mode": "absolute",
+              "steps": [
+                {
+                  "color": "green",
+                  "value": 0
+                },
+                {
+                  "color": "red",
+                  "value": 80
+                }
+              ]
+            },
+            "unit": "none"
+          },
+          "overrides": []
+        },
+        "gridPos": {
+          "h": 8,
+          "w": 6,
+          "x": 18,
+          "y": 1
+        },
+        "id": 4,
+        "options": {
+          "colorMode": "value",
+          "graphMode": "area",
+          "justifyMode": "auto",
+          "orientation": "auto",
+          "percentChangeColorMode": "standard",
+          "reduceOptions": {
+            "calcs": [
+              "lastNotNull"
+            ],
+            "fields": "",
+            "values": false
+          },
+          "showPercentChange": false,
+          "textMode": "auto",
+          "wideLayout": true
+        },
+        "pluginVersion": "12.4.0-21693836646",
+        "targets": [
+          {
+            "datasource": {
+              "type": "prometheus",
+              "uid": "${datasource}"
+            },
+            "editorMode": "code",
+            "expr": "max(telemt_handshake_timeouts_total) by (service)",
+            "format": "time_series",
+            "legendFormat": "__auto",
+            "range": true,
+            "refId": "A"
+          }
+        ],
+        "title": "handshake_timeouts",
+        "type": "stat"
+      },
+      {
+        "collapsed": false,
+        "gridPos": {
+          "h": 1,
+          "w": 24,
+          "x": 0,
+          "y": 9
+        },
+        "id": 6,
+        "panels": [],
+        "repeat": "user",
+        "title": "$user",
+        "type": "row"
+      },
+      {
+        "datasource": {
+          "type": "prometheus",
+          "uid": "${datasource}"
+        },
+        "fieldConfig": {
+          "defaults": {
+            "color": {
+              "mode": "palette-classic"
+            },
+            "custom": {
+              "axisBorderShow": false,
+              "axisCenteredZero": false,
+              "axisColorMode": "text",
+              "axisLabel": "",
+              "axisPlacement": "auto",
+              "barAlignment": 0,
+              "barWidthFactor": 0.6,
+              "drawStyle": "line",
+              "fillOpacity": 0,
+              "gradientMode": "none",
+              "hideFrom": {
+                "legend": false,
+                "tooltip": false,
+                "viz": false
+              },
+              "insertNulls": false,
+              "lineInterpolation": "linear",
+              "lineWidth": 1,
+              "pointSize": 5,
+              "scaleDistribution": {
+                "type": "linear"
+              },
+              "showPoints": "auto",
+              "showValues": false,
+              "spanNulls": false,
+              "stacking": {
+                "group": "A",
+                "mode": "none"
+              },
+              "thresholdsStyle": {
+                "mode": "off"
+              }
+            },
+            "mappings": [],
+            "thresholds": {
+              "mode": "absolute",
+              "steps": [
+                {
+                  "color": "green",
+                  "value": 0
+                },
+                {
+                  "color": "red",
+                  "value": 80
+                }
+              ]
+            },
+            "unit": "none"
+          },
+          "overrides": []
+        },
+        "gridPos": {
+          "h": 8,
+          "w": 12,
+          "x": 0,
+          "y": 10
+        },
+        "id": 7,
+        "options": {
+          "legend": {
+            "calcs": [],
+            "displayMode": "list",
+            "placement": "bottom",
+            "showLegend": false
+          },
+          "tooltip": {
+            "hideZeros": false,
+            "mode": "single",
+            "sort": "none"
+          }
+        },
+        "pluginVersion": "12.4.0-21693836646",
+        "targets": [
+          {
+            "editorMode": "code",
+            "expr": "sum(telemt_user_connections_total{user=\"$user\"}) by (user)",
+            "format": "time_series",
+            "legendFormat": "{{ user }}",
+            "range": true,
+            "refId": "A"
+          }
+        ],
+        "title": "user_connections",
+        "type": "timeseries"
+      },
+      {
+        "datasource": {
+          "type": "prometheus",
+          "uid": "${datasource}"
+        },
+        "fieldConfig": {
+          "defaults": {
+            "color": {
+              "mode": "palette-classic"
+            },
+            "custom": {
+              "axisBorderShow": false,
+              "axisCenteredZero": false,
+              "axisColorMode": "text",
+              "axisLabel": "",
+              "axisPlacement": "auto",
+              "barAlignment": 0,
+              "barWidthFactor": 0.6,
+              "drawStyle": "line",
+              "fillOpacity": 0,
+              "gradientMode": "none",
+              "hideFrom": {
+                "legend": false,
+                "tooltip": false,
+                "viz": false
+              },
+              "insertNulls": false,
+              "lineInterpolation": "linear",
+              "lineWidth": 1,
+              "pointSize": 5,
+              "scaleDistribution": {
+                "type": "linear"
+              },
+              "showPoints": "auto",
+              "showValues": false,
+              "spanNulls": false,
+              "stacking": {
+                "group": "A",
+                "mode": "none"
+              },
+              "thresholdsStyle": {
+                "mode": "off"
+              }
+            },
+            "mappings": [],
+            "thresholds": {
+              "mode": "absolute",
+              "steps": [
+                {
+                  "color": "green",
+                  "value": 0
+                },
+                {
+                  "color": "red",
+                  "value": 80
+                }
+              ]
+            },
+            "unit": "none"
+          },
+          "overrides": []
+        },
+        "gridPos": {
+          "h": 8,
+          "w": 12,
+          "x": 12,
+          "y": 10
+        },
+        "id": 8,
+        "options": {
+          "legend": {
+            "calcs": [],
+            "displayMode": "list",
+            "placement": "bottom",
+            "showLegend": false
+          },
+          "tooltip": {
+            "hideZeros": false,
+            "mode": "single",
+            "sort": "none"
+          }
+        },
+        "pluginVersion": "12.4.0-21693836646",
+        "targets": [
+          {
+            "editorMode": "code",
+            "expr": "sum(telemt_user_connections_current{user=\"$user\"}) by (user)",
+            "format": "time_series",
+            "legendFormat": "{{ user }}",
+            "range": true,
+            "refId": "A"
+          }
+        ],
+        "title": "user_connections_current",
+        "type": "timeseries"
+      },
+      {
+        "datasource": {
+          "type": "prometheus",
+          "uid": "${datasource}"
+        },
+        "fieldConfig": {
+          "defaults": {
+            "color": {
+              "mode": "palette-classic"
+            },
+            "custom": {
+              "axisBorderShow": false,
+              "axisCenteredZero": false,
+              "axisColorMode": "text",
+              "axisLabel": "",
+              "axisPlacement": "auto",
+              "barAlignment": 0,
+              "barWidthFactor": 0.6,
+              "drawStyle": "line",
+              "fillOpacity": 0,
+              "gradientMode": "none",
+              "hideFrom": {
+                "legend": false,
+                "tooltip": false,
+                "viz": false
+              },
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+      "to": "now"
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+    "timepicker": {},
+    "timezone": "browser",
+    "title": "Telemt MtProto proxy",
+    "weekStart": ""
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+}