build + tor: update grin libs fix android build, add arti lib, tor server config, connection with snowflake, transport at connections

Cargo.toml

@@ -16,21 +16,21 @@ log = "0.4"
 
 ## node
 openssl-sys = { version = "0.9.82", features = ["vendored"] }
-grin_api = { git = "https://github.com/mimblewimble/grin", branch = "master" }
-grin_chain = { git = "https://github.com/mimblewimble/grin", branch = "master" }
-grin_config = { git = "https://github.com/mimblewimble/grin", branch = "master" }
-grin_core = { git = "https://github.com/mimblewimble/grin", branch = "master" }
-grin_p2p = { git = "https://github.com/mimblewimble/grin", branch = "master" }
-grin_servers = { git = "https://github.com/mimblewimble/grin", branch = "master" }
-grin_keychain = { git = "https://github.com/mimblewimble/grin", branch = "master" }
-grin_util = { git = "https://github.com/mimblewimble/grin", branch = "master" }
+grin_api = "5.3.0"
+grin_chain = "5.3.0"
+grin_config = "5.3.0"
+grin_core = "5.3.0"
+grin_p2p = "5.3.0"
+grin_servers = "5.3.0"
+grin_keychain = "5.3.0"
+grin_util = "5.3.0"
 
 ## wallet
-grin_wallet_impls = { git = "https://github.com/mimblewimble/grin-wallet", branch = "master" }
-grin_wallet_api = { git = "https://github.com/mimblewimble/grin-wallet", branch = "master" }
-grin_wallet_libwallet = { git = "https://github.com/mimblewimble/grin-wallet", branch = "master" }
-grin_wallet_util = { git = "https://github.com/mimblewimble/grin-wallet", branch = "master" }
-grin_wallet_controller = { git = "https://github.com/mimblewimble/grin-wallet", branch = "master" }
+grin_wallet_impls = "5.3.0"
+grin_wallet_api = "5.3.0"
+grin_wallet_libwallet = "5.3.0"
+grin_wallet_util = "5.3.0"
+grin_wallet_controller = "5.3.0"
 
 ## ui
 egui = { version = "0.27.2", default-features = false }
@@ -38,6 +38,7 @@ egui_extras = { version = "0.27.2", features = ["image"] }
 rust-i18n = "2.3.1"
 
 ## other
+anyhow = "1.0.75"
 thiserror = "1.0.58"
 futures = "0.3"
 dirs = "5.0.1"
@@ -48,13 +49,20 @@ toml = "0.8.2"
 serde = "1.0.170"
 local-ip-address = "0.6.1"
 url = "2.4.0"
-
-## stratum server
+rand = "0.8.5"
 serde_derive = "1.0.197"
 serde_json = "1.0.115"
-tokio = {version = "1.29.1", features = ["full"] }
+tokio = { version = "1.37.0", features = ["full"] }
+
+## tor
+arti = { version = "1.2.0", features = ["experimental-api", "pt-client", "static"] }
+arti-client = { version = "0.17.0", features = ["experimental-api", "pt-client", "static"] }
+tor-rtcompat = { version = "0.17.0", features = ["static"] }
+tor-config = "0.17.0"
+fs-mistrust = "0.7.9"
+
+## stratum server
 tokio-util = { version = "0.7.8", features = ["codec"] }
-rand = "0.8.5"
 
 [build-dependencies]
 built = { version = "0.7.0", features = ["git2"]}
@@ -70,5 +78,6 @@ image = "0.25.1"
 android_logger = "0.13.1"
 jni = "0.21.1"
 android-activity = "0.5.2"
+wgpu = "0.19"
 winit = { version = "0.29", features = [ "android-game-activity" ] }
 eframe = { version = "0.27.2", features = [ "wgpu", "android-game-activity" ] }

android/app/src/main/java/mw/gri/android/MainActivity.java

@@ -40,6 +40,7 @@ public class MainActivity extends GameActivity {
         try {
             Os.setenv("HOME", getExternalFilesDir("").getPath(), true);
             Os.setenv("XDG_CACHE_HOME", getExternalCacheDir().getPath(), true);
+            Os.setenv("ARTI_FS_DISABLE_PERMISSION_CHECKS", "true", true);
         } catch (ErrnoException e) {
             throw new RuntimeException(e);
         }

locales/en.yml

@@ -126,6 +126,12 @@ network:
   available: Available
   not_available: Not available
   availability_check: Availability check
+  tor_network: Tor network
+  server_enabled: Server enabled
+  server_starting: Server is starting
+  server_stopping: Server is stopping
+  server_error: Server error
+  server_disabled: Server disabled
 sync_status:
   node_restarting: Node is restarting
   node_down: Node is down

locales/ru.yml

@@ -126,6 +126,12 @@ network:
   available: Доступно
   not_available: Недоступно
   availability_check: Проверка доступности
+  tor_network: Сеть Tor
+  server_enabled: Сервер включен
+  server_starting: Сервер запускается
+  server_stopping: Сервер останавливается
+  server_error: Ошибка сервера
+  server_disabled: Сервер отключен
 sync_status:
   node_restarting: Узел перезапускается
   node_down: Узел выключен

src/gui/views/network/connections.rs

@@ -17,11 +17,12 @@ use url::Url;
 
 use crate::AppConfig;
 use crate::gui::Colors;
-use crate::gui::icons::{CARET_RIGHT, CHECK_CIRCLE, COMPUTER_TOWER, DOTS_THREE_CIRCLE, PENCIL, POWER, TRASH, X_CIRCLE};
+use crate::gui::icons::{CARET_RIGHT, CHECK_CIRCLE, COMPUTER_TOWER, DOTS_THREE_CIRCLE, GEAR_SIX, PENCIL, POWER, TRASH, WARNING_CIRCLE, X_CIRCLE};
 use crate::gui::platform::PlatformCallbacks;
 use crate::gui::views::{Modal, NodeSetup, View};
 use crate::gui::views::types::{ModalContainer, ModalPosition, TextEditOptions};
 use crate::node::{Node, NodeConfig};
+use crate::tor::{TorServer, TorServerConfig};
 use crate::wallet::{ConnectionsConfig, ExternalConnection};
 
 /// Network connections content.
@@ -99,12 +100,21 @@ impl ConnectionsContent {
         // Show integrated node info content.
         Self::integrated_node_item_ui(ui);
 
+        // Show transport connections.
+        ui.add_space(6.0);
+        let transport_text = format!("{}:", t!("wallets.transport"));
+        ui.label(RichText::new(transport_text).size(16.0).color(Colors::GRAY));
+        ui.add_space(6.0);
+
+        // Show Tor SOCKS server.
+        Self::tor_transport_item_ui(ui);
+
+        // Show external connections.
         let ext_conn_list = ConnectionsConfig::ext_conn_list();
         if !ext_conn_list.is_empty() {
             ui.add_space(6.0);
             ui.label(RichText::new(t!("wallets.ext_conn")).size(16.0).color(Colors::GRAY));
             ui.add_space(6.0);
-            // Show external connections.
             for (index, conn) in ext_conn_list.iter().enumerate() {
                 ui.horizontal_wrapped(|ui| {
                     // Draw connection list item.
@@ -114,6 +124,67 @@ impl ConnectionsContent {
         }
     }
 
+    /// Draw Tor connection item content.
+    fn tor_transport_item_ui(ui: &mut egui::Ui) {
+        // Draw round background.
+        let mut rect = ui.available_rect_before_wrap();
+        rect.set_height(78.0);
+        let rounding = View::item_rounding(0, 1, false);
+        ui.painter().rect(rect, rounding, Colors::FILL, View::ITEM_STROKE);
+
+        ui.allocate_ui_with_layout(rect.size(), Layout::right_to_left(Align::Center), |ui| {
+            // Draw button to show Tor connection settings.
+            View::item_button(ui, View::item_rounding(0, 1, true), GEAR_SIX, None, || {
+                AppConfig::toggle_show_connections_network_panel();
+            });
+
+            // Draw buttons to stop or start Tor server.
+            if !TorServer::is_stopping() && !TorServer::is_starting() {
+                if TorServer::is_running() {
+                    View::item_button(ui, Rounding::default(), POWER, Some(Colors::RED), || {
+                        TorServer::stop();
+                    });
+                } else {
+                    View::item_button(ui, Rounding::default(), POWER, Some(Colors::GREEN), || {
+                        TorServer::start();
+                    });
+                }
+            }
+
+            let layout_size = ui.available_size();
+            ui.allocate_ui_with_layout(layout_size, Layout::left_to_right(Align::Center), |ui| {
+                ui.add_space(6.0);
+                ui.vertical(|ui| {
+                    ui.add_space(3.0);
+                    ui.label(RichText::new(t!("network.tor_network"))
+                        .size(18.0)
+                        .color(Colors::TITLE));
+
+                    // Setup SOCKS server address.
+                    let socks_port = TorServerConfig::socks_port();
+                    let addr_text = format!("{} http://127.0.0.1:{}", COMPUTER_TOWER, socks_port);
+                    ui.label(RichText::new(addr_text).size(15.0).color(Colors::TEXT));
+                    ui.add_space(1.0);
+
+                    // Setup server status text.
+                    let (status_icon, status_text) = if TorServer::has_error() {
+                        (WARNING_CIRCLE, t!("network.server_error"))
+                    } else if TorServer::is_starting() {
+                        (DOTS_THREE_CIRCLE, t!("network.server_starting"))
+                    } else if TorServer::is_stopping() {
+                        (DOTS_THREE_CIRCLE, t!("network.server_stopping"))
+                    } else if TorServer::is_running() {
+                        (CHECK_CIRCLE, t!("network.server_enabled"))
+                    } else {
+                        (X_CIRCLE, t!("network.server_disabled"))
+                    };
+                    let status_text = format!("{} {}", status_icon, status_text);
+                    ui.label(RichText::new(status_text).size(15.0).color(Colors::GRAY));
+                })
+            });
+        });
+    }
+
     /// Draw integrated node connection item content.
     fn integrated_node_item_ui(ui: &mut egui::Ui) {
         // Draw round background.
@@ -123,9 +194,6 @@ impl ConnectionsContent {
         ui.painter().rect(rect, rounding, Colors::FILL, View::ITEM_STROKE);
 
         ui.allocate_ui_with_layout(rect.size(), Layout::right_to_left(Align::Center), |ui| {
-            // Setup padding for item buttons.
-            ui.style_mut().spacing.button_padding = egui::vec2(14.0, 0.0);
-
             // Draw button to show integrated node info.
             View::item_button(ui, View::item_rounding(0, 1, true), CARET_RIGHT, None, || {
                 AppConfig::toggle_show_connections_network_panel();
@@ -137,7 +205,7 @@ impl ConnectionsContent {
                     Node::start();
                 });
             } else if !Node::is_starting() && !Node::is_stopping() && !Node::is_restarting() {
-                // Draw button to open closed wallet.
+                // Draw button to stop integrated node.
                 View::item_button(ui, Rounding::default(), POWER, Some(Colors::RED), || {
                     Node::stop(false);
                 });

src/gui/views/network/content.rs

@@ -22,6 +22,7 @@ use crate::gui::views::{ConnectionsContent, NetworkMetrics, NetworkMining, Netwo
 use crate::gui::views::network::types::{NetworkTab, NetworkTabType};
 use crate::gui::views::types::{TitleContentType, TitleType};
 use crate::node::Node;
+use crate::tor::TorServer;
 use crate::wallet::ExternalConnection;
 
 /// Network content.
@@ -147,7 +148,8 @@ impl NetworkContent {
             });
 
         // Redraw after delay if node is syncing to update stats.
-        if Node::is_running() {
+        if Node::is_running() || TorServer::is_running() || TorServer::is_starting() ||
+            TorServer::is_stopping() {
             ui.ctx().request_repaint_after(Node::STATS_UPDATE_DELAY);
         }
     }

src/lib.rs

@@ -32,7 +32,7 @@ i18n!("locales");
 
 mod node;
 mod wallet;
-
+mod tor;
 mod settings;
 pub mod gui;
 
@@ -63,8 +63,9 @@ fn android_main(app: AndroidApp) {
 
     let width = app.config().screen_width_dp().unwrap() as f32;
     let height = app.config().screen_height_dp().unwrap() as f32;
+    let size = egui::emath::vec2(width, height);
     let mut options = eframe::NativeOptions {
-        viewport: egui::ViewportBuilder::default().with_inner_size(vec2(width, height)),
+        viewport: egui::ViewportBuilder::default().with_inner_size(size),
         ..Default::default()
     };
     // Setup limits that are guaranteed to be compatible with Android devices.

src/settings/settings.rs

@@ -24,6 +24,7 @@ use serde::Serialize;
 
 use crate::node::NodeConfig;
 use crate::settings::AppConfig;
+use crate::tor::TorServerConfig;
 use crate::wallet::ConnectionsConfig;
 
 lazy_static! {
@@ -42,18 +43,27 @@ pub struct Settings {
     node_config: Arc<RwLock<NodeConfig>>,
     /// Wallet connections configuration.
     conn_config: Arc<RwLock<ConnectionsConfig>>,
+    /// Tor server configuration.
+    tor_config: Arc<RwLock<TorServerConfig>>
 }
 
 impl Settings {
     /// Initialize settings with app and node configs.
     fn init() -> Self {
+        // Initialize app config.
         let app_config_path = Settings::get_config_path(AppConfig::FILE_NAME, None);
         let app_config = Self::init_config::<AppConfig>(app_config_path);
+
+        // Initialize tor config.
+        let tor_config_path = Settings::get_config_path(TorServerConfig::FILE_NAME, None);
+        let tor_config = Self::init_config::<TorServerConfig>(tor_config_path);
+
         let chain_type = &app_config.chain_type;
         Self {
             node_config: Arc::new(RwLock::new(NodeConfig::for_chain_type(chain_type))),
             conn_config: Arc::new(RwLock::new(ConnectionsConfig::for_chain_type(chain_type))),
             app_config: Arc::new(RwLock::new(app_config)),
+            tor_config: Arc::new(RwLock::new(tor_config)),
         }
     }
 
@@ -99,6 +109,16 @@ impl Settings {
         SETTINGS_STATE.conn_config.write().unwrap()
     }
 
+    /// Get tor server configuration to read values.
+    pub fn tor_config_to_read() -> RwLockReadGuard<'static, TorServerConfig> {
+        SETTINGS_STATE.tor_config.read().unwrap()
+    }
+
+    /// Get tor server configuration to update values.
+    pub fn tor_config_to_update() -> RwLockWriteGuard<'static, TorServerConfig> {
+        SETTINGS_STATE.tor_config.write().unwrap()
+    }
+
     /// Get base directory path for configuration.
     pub fn get_base_path(sub_dir: Option<String>) -> PathBuf {
         // Check if dir exists.

src/tor/config.rs

@@ -0,0 +1,56 @@
+// Copyright 2024 The Grim Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use serde_derive::{Deserialize, Serialize};
+use crate::Settings;
+
+/// Tor SOCKS proxy server configuration.
+#[derive(Serialize, Deserialize, Clone)]
+pub struct TorServerConfig {
+    socks_port: u16
+}
+
+/// Default SOCKS port value.
+const DEFAULT_SOCKS_PORT: u16 = 9060;
+
+impl Default for TorServerConfig {
+    fn default() -> Self {
+        Self {
+            socks_port: DEFAULT_SOCKS_PORT,
+        }
+    }
+}
+
+impl TorServerConfig {
+    /// Application configuration file name.
+    pub const FILE_NAME: &'static str = "app.toml";
+
+    /// Save application configuration to the file.
+    pub fn save(&self) {
+        Settings::write_to_file(self, Settings::get_config_path(Self::FILE_NAME, None));
+    }
+
+    /// Get SOCKS port value.
+    pub fn socks_port() -> u16 {
+        let r_config = Settings::tor_config_to_read();
+        r_config.socks_port
+    }
+
+    /// Save SOCKS port value.
+    pub fn save_socks_port(port: u16) {
+        let mut w_config = Settings::tor_config_to_update();
+        w_config.socks_port = port;
+        w_config.save();
+    }
+}

src/tor/mod.rs

@@ -0,0 +1,19 @@
+// Copyright 2024 The Grim Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+mod config;
+pub use config::TorServerConfig;
+
+mod tor;
+pub use tor::TorServer;

src/tor/tor.rs

@@ -0,0 +1,228 @@
+// Copyright 2024 The Grim Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::sync::{Arc, RwLock};
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::thread;
+use std::time::Duration;
+use lazy_static::lazy_static;
+use arti::socks::run_socks_proxy;
+use arti_client::{TorClient, TorClientConfig};
+use arti_client::config::pt::{TransportConfigBuilder};
+use arti_client::config::{BridgeConfigBuilder, TorClientConfigBuilder, StorageConfigBuilder};
+use futures::task::SpawnExt;
+use tokio::task::JoinHandle;
+use anyhow::{Result};
+use tokio::time::sleep;
+use tor_config::{CfgPath, Listen};
+use tor_rtcompat::{BlockOn, Runtime};
+use tor_rtcompat::tokio::TokioNativeTlsRuntime;
+
+use crate::tor::TorServerConfig;
+
+lazy_static! {
+    /// Static thread-aware state of [`Node`] to be updated from separate thread.
+    static ref TOR_SERVER_STATE: Arc<TorServer> = Arc::new(TorServer::default());
+}
+
+/// Tor SOCKS proxy server.
+pub struct TorServer {
+    /// Flag to check if server is running.
+    running: AtomicBool,
+    /// Flag to check if server is starting.
+    starting: AtomicBool,
+    /// Flag to check if server needs to stop.
+    stopping: AtomicBool,
+    /// Flag to check if error happened.
+    error: AtomicBool,
+    /// Tor client to use for proxy.
+    client: Arc<RwLock<Option<TorClient<TokioNativeTlsRuntime>>>>
+}
+
+impl Default for TorServer {
+    fn default() -> Self {
+        Self {
+            running: AtomicBool::new(false),
+            starting: AtomicBool::new(false),
+            stopping: AtomicBool::new(false),
+            error: AtomicBool::new(false),
+            client: Arc::new(RwLock::new(None)),
+        }
+    }
+}
+
+impl TorServer {
+    /// Check if server is running.
+    pub fn is_running() -> bool {
+        TOR_SERVER_STATE.running.load(Ordering::Relaxed)
+    }
+
+    /// Check if server is running.
+    pub fn is_starting() -> bool {
+        TOR_SERVER_STATE.starting.load(Ordering::Relaxed)
+    }
+
+    /// Check if server is stopping.
+    pub fn is_stopping() -> bool {
+        TOR_SERVER_STATE.stopping.load(Ordering::Relaxed)
+    }
+
+    /// Check if server has error.
+    pub fn has_error() -> bool {
+        TOR_SERVER_STATE.error.load(Ordering::Relaxed)
+    }
+
+    /// Stop the server.
+    pub fn stop() {
+        TOR_SERVER_STATE.stopping.store(true, Ordering::Relaxed);
+    }
+
+    /// Start or restart the server if already running.
+    pub fn start() {
+        if Self::is_running() {
+            Self::stop();
+        }
+
+        thread::spawn(|| {
+            while Self::is_stopping() {
+                thread::sleep(Duration::from_millis(1000));
+            }
+            TOR_SERVER_STATE.starting.store(true, Ordering::Relaxed);
+            TOR_SERVER_STATE.error.store(false, Ordering::Relaxed);
+
+            // Check if Tor client is already running.
+            if TOR_SERVER_STATE.client.read().unwrap().is_some() {
+                let r_client = TOR_SERVER_STATE.client.read().unwrap();
+                let runtime = TokioNativeTlsRuntime::create().unwrap();
+                let _ = runtime.clone().block_on(
+                    Self::launch_socks_proxy(runtime, r_client.as_ref().unwrap().clone())
+                );
+            } else {
+                // Create Tor client config to connect.
+                let mut builder = TorClientConfig::builder();
+
+                // Setup Snowflake bridges.
+                Self::setup_bridges(&mut builder);
+
+                // Create Tor client from config.
+                if let Ok(config) = builder.build() {
+                    // Restart server on connection timeout.
+                    thread::spawn(|| {
+                        thread::sleep(Duration::from_millis(30000));
+                        let r_client = TOR_SERVER_STATE.client.read().unwrap();
+                        if r_client.is_none() {
+                            Self::start();
+                        }
+                    });
+                    // Create Tor client.
+                    let runtime = TokioNativeTlsRuntime::create().unwrap();
+                    match TorClient::with_runtime(runtime.clone())
+                        .config(config)
+                        .bootstrap_behavior(arti_client::BootstrapBehavior::OnDemand)
+                        .create_unbootstrapped() {
+                        Ok(tor_client) => {
+                            let mut w_client = TOR_SERVER_STATE.client.write().unwrap();
+                            if w_client.is_some() {
+                                return;
+                            }
+                            *w_client = Some(tor_client.clone());
+                            let _ = runtime.clone().block_on(
+                                // Launch SOCKS proxy server.
+                                Self::launch_socks_proxy(runtime, tor_client)
+                            );
+                        }
+                        Err(e) => {
+                            eprintln!("{}", e);
+                            TOR_SERVER_STATE.starting.store(false, Ordering::Relaxed);
+                            TOR_SERVER_STATE.error.store(true, Ordering::Relaxed);
+                        }
+                    }
+                } else {
+                    TOR_SERVER_STATE.starting.store(false, Ordering::Relaxed);
+                    TOR_SERVER_STATE.error.store(true, Ordering::Relaxed);
+                }
+            }
+        });
+    }
+
+    /// Launch SOCKS proxy server.
+    async fn launch_socks_proxy<R: Runtime>(runtime: R, tor_client: TorClient<R>) -> Result<()> {
+        let proxy_handle: JoinHandle<Result<()>> = tokio::spawn(
+            run_socks_proxy(
+                runtime,
+                tor_client,
+                Listen::new_localhost(TorServerConfig::socks_port()),
+            )
+        );
+
+        // Setup server state flags.
+        TOR_SERVER_STATE.starting.store(false, Ordering::Relaxed);
+        TOR_SERVER_STATE.running.store(true, Ordering::Relaxed);
+
+        loop {
+            if Self::is_stopping() || proxy_handle.is_finished() {
+                proxy_handle.abort();
+                TOR_SERVER_STATE.stopping.store(false, Ordering::Relaxed);
+                TOR_SERVER_STATE.running.store(false, Ordering::Relaxed);
+                return Ok(());
+            }
+            sleep(Duration::from_millis(3000)).await;
+        }
+    }
+
+    /// Setup Tor Snowflake bridges.
+    fn setup_bridges(builder: &mut TorClientConfigBuilder) {
+        // Add a single bridge to the list of bridges, from a bridge line.
+        // This line comes from https://gitlab.torproject.org/tpo/applications/tor-browser-build/-/blob/main/projects/common/bridges_list.snowflake.txt
+        // this is a real bridge line you can use as-is, after making sure it's still up to date with
+        // above link.
+        const BRIDGE1_LINE: &str = "Bridge snowflake 192.0.2.3:80 2B280B23E1107BB62ABFC40DDCC8824814F80A72 fingerprint=2B280B23E1107BB62ABFC40DDCC8824814F80A72 url=https://snowflake-broker.torproject.net.global.prod.fastly.net/ front=cdn.sstatic.net ice=stun:stun.l.google.com:19302,stun:stun.antisip.com:3478,stun:stun.bluesip.net:3478,stun:stun.dus.net:3478,stun:stun.epygi.com:3478,stun:stun.sonetel.com:3478,stun:stun.uls.co.za:3478,stun:stun.voipgate.com:3478,stun:stun.voys.nl:3478 utls-imitate=hellorandomizedalpn";
+        let bridge_1: BridgeConfigBuilder = BRIDGE1_LINE.parse().unwrap();
+        builder.bridges().bridges().push(bridge_1);
+
+        // Add a second bridge, built by hand. We use the 2nd bridge line from above, but modify some
+        // parameters to use AMP Cache instead of Fastly as a signaling channel. The difference in
+        // configuration is detailed in
+        // https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/tree/main/client#amp-cache
+        let mut bridge2_builder = BridgeConfigBuilder::default();
+        bridge2_builder
+            .transport("snowflake")
+            .push_setting(
+                "fingerprint",
+                "8838024498816A039FCBBAB14E6F40A0843051FA"
+            )
+            .push_setting("url", "https://snowflake-broker.torproject.net/")
+            .push_setting("ampcache", "https://cdn.ampproject.org/")
+            .push_setting("front", "www.google.com")
+            .push_setting(
+                "ice",
+                "stun:stun.l.google.com:19302,stun:stun.antisip.com:3478,stun:stun.bluesip.net:3478,stun:stun.dus.net:3478,stun:stun.epygi.com:3478,stun:stun.sonetel.net:3478,stun:stun.uls.co.za:3478,stun:stun.voipgate.com:3478,stun:stun.voys.nl:3478",
+            )
+            .push_setting("utls-imitate", "hellorandomizedalpn");
+        bridge2_builder.set_addrs(vec!["192.0.2.4:80".parse().unwrap()]);
+        bridge2_builder.set_ids(vec!["8838024498816A039FCBBAB14E6F40A0843051FA".parse().unwrap()]);
+        // Now insert the second bridge into our config builder.
+        builder.bridges().bridges().push(bridge2_builder);
+
+        // Now configure an snowflake transport. (Requires the "pt-client" feature)
+        let mut transport = TransportConfigBuilder::default();
+        transport
+            .protocols(vec!["snowflake".parse().unwrap()])
+            // this might be named differently on some systems, this should work on Debian,
+            // but Archlinux is known to use `snowflake-pt-client` instead for instance.
+            .path(CfgPath::new("snowflake-client".into()))
+            .run_on_startup(true);
+        builder.bridges().transports().push(transport);
+    }
+}