Add server list persistence and UDP ping to platform trait

Add ServerEntry model, load_servers/save_servers/set_default_server
to PlatformInterface with implementations for desktop (etcetera config),
web (localStorage), mobile (stub), and stub platforms. Implement
mumble_udp_ping protocol on desktop for direct server status queries.

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

common/src/lib.rs

@@ -16,3 +16,13 @@ pub struct ServerStatus {
     pub max_users: Option<u32>,
     pub bandwidth: Option<u32>,
 }
+
+#[derive(Debug, Clone, Deserialize, Serialize, Default, PartialEq)]
+pub struct ServerEntry {
+    pub name: String,
+    pub address: String,
+    pub port: u16,
+    pub username: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub password: Option<String>,
+}

gui/src/imp/desktop.rs

@@ -1,7 +1,9 @@
 use crate::app::{Command, SharedState};
-use color_eyre::eyre::Error;
+use color_eyre::eyre::{bail, Error};
 use dioxus::hooks::UnboundedReceiver;
-use mumble_web2_common::{ProxyOverrides, ServerStatus};
+use etcetera::{choose_app_strategy, AppStrategy, AppStrategyArgs};
+use mumble_web2_common::{ProxyOverrides, ServerEntry, ServerStatus};
+use std::collections::HashMap;
 use std::time::Duration;
 
 /// Desktop platform implementation using Tokio and native audio.
@@ -37,6 +39,32 @@ impl super::PlatformInterface for DesktopPlatform {
         super::connect::get_status(client).await
     }
 
+    async fn ping_server(address: &str, port: u16) -> color_eyre::Result<ServerStatus> {
+        mumble_udp_ping(address, port).await
+    }
+
+    fn set_default_server(server: &str) -> Option<()> {
+        let mut config = load_config_map();
+        config.insert("server".to_string(), server.to_string());
+        save_config_map(&config).ok()
+    }
+
+    fn load_servers() -> Vec<ServerEntry> {
+        let config = load_config_map();
+        config
+            .get("servers")
+            .and_then(|s| serde_json::from_str(s).ok())
+            .unwrap_or_default()
+    }
+
+    fn save_servers(servers: &[ServerEntry]) {
+        let mut config = load_config_map();
+        if let Ok(json) = serde_json::to_string(servers) {
+            config.insert("servers".to_string(), json);
+            let _ = save_config_map(&config);
+        }
+    }
+
     fn init_logging() {
         use tracing::level_filters::LevelFilter;
         use tracing_subscriber::filter::EnvFilter;
@@ -56,3 +84,85 @@ impl super::PlatformInterface for DesktopPlatform {
         // No-op on desktop
     }
 }
+
+fn get_config_path() -> std::path::PathBuf {
+    let strategy = choose_app_strategy(AppStrategyArgs {
+        top_level_domain: "xyz".to_string(),
+        author: "ohea".to_string(),
+        app_name: "Mumble Web2".to_string(),
+    })
+    .expect("failed to choose app strategy");
+    strategy.config_dir().join("config.json")
+}
+
+fn load_config_map() -> HashMap<String, String> {
+    let config_path = get_config_path();
+    match std::fs::read_to_string(&config_path) {
+        Ok(contents) => serde_json::from_str(&contents).unwrap_or_default(),
+        Err(_) => HashMap::new(),
+    }
+}
+
+fn save_config_map(config: &HashMap<String, String>) -> color_eyre::Result<()> {
+    let config_path = get_config_path();
+    if let Some(parent) = config_path.parent() {
+        std::fs::create_dir_all(parent)?;
+    }
+    let contents = serde_json::to_string_pretty(config)?;
+    std::fs::write(&config_path, contents)?;
+    Ok(())
+}
+
+/// Mumble UDP ping protocol.
+///
+/// Send a 12-byte packet: 4 zero bytes + 8-byte identifier.
+/// Receive a 24-byte response: 4 bytes version (1 byte each: major.minor.patch + padding)
+/// + 8 bytes identifier echo + 4 bytes current_users + 4 bytes max_users + 4 bytes bandwidth.
+async fn mumble_udp_ping(address: &str, port: u16) -> color_eyre::Result<ServerStatus> {
+    use std::net::ToSocketAddrs;
+    use tokio::net::UdpSocket;
+
+    let dest = format!("{}:{}", address, port)
+        .to_socket_addrs()?
+        .next()
+        .ok_or_else(|| color_eyre::eyre::eyre!("could not resolve address"))?;
+
+    let bind_addr = if dest.is_ipv6() { "[::]:0" } else { "0.0.0.0:0" };
+    let socket = UdpSocket::bind(bind_addr).await?;
+    socket.connect(dest).await?;
+
+    // Build ping packet: 4 zero bytes + 8-byte request ID
+    let request_id: u64 = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_nanos() as u64;
+
+    let mut buf = [0u8; 12];
+    buf[4..12].copy_from_slice(&request_id.to_be_bytes());
+    socket.send(&buf).await?;
+
+    let mut response = [0u8; 24];
+    let timeout = tokio::time::timeout(Duration::from_secs(2), socket.recv(&mut response)).await;
+
+    match timeout {
+        Ok(Ok(len)) if len >= 24 => {
+            let version_major = response[0] as u32;
+            let version_minor = response[1] as u32;
+            let version_patch = response[2] as u32;
+            let users = u32::from_be_bytes([response[12], response[13], response[14], response[15]]);
+            let max_users = u32::from_be_bytes([response[16], response[17], response[18], response[19]]);
+            let bandwidth = u32::from_be_bytes([response[20], response[21], response[22], response[23]]);
+
+            Ok(ServerStatus {
+                success: true,
+                version: Some((version_major, version_minor, version_patch)),
+                users: Some(users),
+                max_users: Some(max_users),
+                bandwidth: Some(bandwidth),
+            })
+        }
+        Ok(Ok(_)) => bail!("ping response too short"),
+        Ok(Err(e)) => Err(e.into()),
+        Err(_) => bail!("ping timed out"),
+    }
+}

gui/src/imp/mobile.rs

@@ -1,7 +1,7 @@
 use crate::app::{Command, SharedState};
 use color_eyre::eyre::Error;
 use dioxus::hooks::UnboundedReceiver;
-use mumble_web2_common::{ProxyOverrides, ServerStatus};
+use mumble_web2_common::{ProxyOverrides, ServerEntry, ServerStatus};
 use std::time::Duration;
 
 /// Mobile platform implementation using Tokio, native audio, and Android permissions.
@@ -33,6 +33,20 @@ impl super::PlatformInterface for MobilePlatform {
         super::connect::get_status(client).await
     }
 
+    async fn ping_server(_address: &str, _port: u16) -> color_eyre::Result<ServerStatus> {
+        color_eyre::eyre::bail!("ping not supported on mobile yet")
+    }
+
+    fn set_default_server(_server: &str) -> Option<()> {
+        None
+    }
+
+    fn load_servers() -> Vec<ServerEntry> {
+        Vec::new()
+    }
+
+    fn save_servers(_servers: &[ServerEntry]) {}
+
     fn init_logging() {
         use tracing::level_filters::LevelFilter;
         use tracing_subscriber::filter::EnvFilter;

gui/src/imp/mod.rs

@@ -8,7 +8,7 @@ use crate::app::{Command, SharedState};
 use crate::effects::AudioProcessor;
 use color_eyre::eyre::Error;
 use dioxus::hooks::UnboundedReceiver;
-use mumble_web2_common::{ProxyOverrides, ServerStatus};
+use mumble_web2_common::{ProxyOverrides, ServerEntry, ServerStatus};
 use std::collections::HashMap;
 use std::future::Future;
 use std::time::Duration;
@@ -91,9 +91,24 @@ pub trait PlatformInterface {
         client: &reqwest::Client,
     ) -> impl Future<Output = color_eyre::Result<ServerStatus>>;
 
+    /// Ping a mumble server via UDP to get version, user count, etc.
+    fn ping_server(
+        address: &str,
+        port: u16,
+    ) -> impl Future<Output = color_eyre::Result<ServerStatus>>;
+
     /// Load the proxy overrides (proxy URL, cert hash, etc.).
     fn load_proxy_overrides() -> impl Future<Output = color_eyre::Result<ProxyOverrides>>;
 
+    /// Save the default server URL.
+    fn set_default_server(server: &str) -> Option<()>;
+
+    /// Load the saved server list.
+    fn load_servers() -> Vec<ServerEntry>;
+
+    /// Save the server list.
+    fn save_servers(servers: &[ServerEntry]);
+
     /// Async sleep for the given duration.
     fn sleep(duration: Duration) -> impl Future<Output = ()>;
 }

gui/src/imp/stub.rs

@@ -3,7 +3,7 @@
 use crate::{app::SharedState, effects::AudioProcessor};
 use color_eyre::eyre::Error;
 use dioxus::hooks::UnboundedReceiver;
-use mumble_web2_common::{ProxyOverrides, ServerStatus};
+use mumble_web2_common::{ProxyOverrides, ServerEntry, ServerStatus};
 use std::future::Future;
 
 pub struct StubPlatform;
@@ -36,10 +36,29 @@ impl super::PlatformInterface for StubPlatform {
         async { panic!("stubbed platform") }
     }
 
+    fn ping_server(
+        _address: &str,
+        _port: u16,
+    ) -> impl Future<Output = color_eyre::Result<ServerStatus>> {
+        async { panic!("stubbed platform") }
+    }
+
     fn load_proxy_overrides() -> impl Future<Output = color_eyre::Result<ProxyOverrides>> {
         async { panic!("stubbed platform") }
     }
 
+    fn set_default_server(_server: &str) -> Option<()> {
+        panic!("stubbed platform")
+    }
+
+    fn load_servers() -> Vec<ServerEntry> {
+        panic!("stubbed platform")
+    }
+
+    fn save_servers(_servers: &[ServerEntry]) {
+        panic!("stubbed platform")
+    }
+
     fn sleep(_duration: std::time::Duration) -> impl Future<Output = ()> {
         async { panic!("stubbed platform") }
     }

gui/src/imp/web.rs

@@ -6,7 +6,7 @@ use dioxus::prelude::*;
 use gloo_timers::future::TimeoutFuture;
 use js_sys::Float32Array;
 use mumble_protocol::control::ClientControlCodec;
-use mumble_web2_common::{ProxyOverrides, ServerStatus};
+use mumble_web2_common::{ProxyOverrides, ServerEntry, ServerStatus};
 use reqwest::Url;
 use std::collections::HashMap;
 use std::future::Future;
@@ -125,6 +125,33 @@ impl super::PlatformInterface for WebPlatform {
             .await?)
     }
 
+    async fn ping_server(_address: &str, _port: u16) -> color_eyre::Result<ServerStatus> {
+        // UDP ping not available in browsers; use get_status via HTTP proxy instead
+        color_eyre::eyre::bail!("UDP ping not supported on web platform")
+    }
+
+    fn set_default_server(_server: &str) -> Option<()> {
+        None
+    }
+
+    fn load_servers() -> Vec<ServerEntry> {
+        web_sys::window()
+            .and_then(|w| w.local_storage().ok()?)
+            .and_then(|s| s.get_item("servers").ok()?)
+            .and_then(|json| serde_json::from_str(&json).ok())
+            .unwrap_or_default()
+    }
+
+    fn save_servers(servers: &[ServerEntry]) {
+        if let Ok(json) = serde_json::to_string(servers) {
+            if let Some(storage) = web_sys::window()
+                .and_then(|w| w.local_storage().ok()?)
+            {
+                let _ = storage.set_item("servers", &json);
+            }
+        }
+    }
+
     async fn sleep(duration: Duration) {
         TimeoutFuture::new(duration.as_millis() as u32).await;
     }