mdns improved peer discovery

crates/lanspread-mdns/src/lib.rs

@@ -47,25 +47,37 @@ impl Drop for MdnsAdvertiser {
     }
 }
 
-pub fn discover_service(
+pub struct MdnsBrowser {
-    service_type: &str,
+    daemon: ServiceDaemon,
+    receiver: Receiver<ServiceEvent>,
+    service_type: String,
+}
+
+impl MdnsBrowser {
+    pub fn new(service_type: &str) -> eyre::Result<Self> {
+        let daemon = ServiceDaemon::new()?;
+        let receiver = daemon.browse(service_type)?;
+        Ok(Self {
+            daemon,
+            receiver,
+            service_type: service_type.to_string(),
+        })
+    }
+
+    pub fn next_address(
+        &self,
         ignore_addr: Option<SocketAddr>,
-) -> eyre::Result<SocketAddr> {
+    ) -> eyre::Result<Option<SocketAddr>> {
-    let mdns = ServiceDaemon::new().expect("Failed to create mDNS daemon.");
+        loop {
-
+            match self.receiver.recv() {
-    let receiver = mdns.browse(service_type)?;
+                Ok(ServiceEvent::ServiceResolved(info)) => {
-
-    while let Ok(event) = receiver.recv() {
-        match event {
-            ServiceEvent::ServiceResolved(info) => {
                     log::trace!("mdns ServiceResolved event: {info:?}");
 
-                // Check if this service matches our expected service type
+                    if info.ty_domain != self.service_type {
-                if info.ty_domain != service_type {
                         log::trace!(
                             "Got mDNS with uninteresting service type: {} (expected: {})",
                             info.ty_domain,
-                        service_type,
+                            self.service_type,
                         );
                         continue;
                     }
@@ -81,7 +93,7 @@ pub fn discover_service(
                         }
 
                         log::info!("Found server at {addr}");
-                    return Ok(addr);
+                        return Ok(Some(addr));
                     }
 
                     if ignored_match {
@@ -94,10 +106,32 @@ pub fn discover_service(
 
                     log::error!("No address found in mDNS response: {info:?}");
                 }
-            other_event => {
+                Ok(other_event) => {
                     log::trace!("mdns unrelated event: {other_event:?}");
                 }
+                Err(err) => {
+                    log::error!("mDNS browse channel closed: {err}");
+                    return Ok(None);
+                }
+            }
         }
     }
-    bail!("No server found.")
+}
+
+impl Drop for MdnsBrowser {
+    fn drop(&mut self) {
+        let _ = self.daemon.shutdown();
+    }
+}
+
+pub fn discover_service(
+    service_type: &str,
+    ignore_addr: Option<SocketAddr>,
+) -> eyre::Result<SocketAddr> {
+    // Currently unused; kept for potential one-off discovery callers that just need a single address.
+    let browser = MdnsBrowser::new(service_type)?;
+    match browser.next_address(ignore_addr)? {
+        Some(addr) => Ok(addr),
+        None => bail!("No server found."),
+    }
 }

crates/lanspread-peer/src/lib.rs

@@ -14,7 +14,7 @@ use std::{
 use bytes::BytesMut;
 use if_addrs::{IfAddr, Interface, get_if_addrs};
 use lanspread_db::db::{Game, GameDB, GameFileDescription};
-use lanspread_mdns::{LANSPREAD_SERVICE_TYPE, MdnsAdvertiser, discover_service};
+use lanspread_mdns::{LANSPREAD_SERVICE_TYPE, MdnsAdvertiser, MdnsBrowser};
 use lanspread_proto::{Message, Request, Response};
 use s2n_quic::{
     Client as QuicClient,
@@ -273,6 +273,11 @@ impl PeerGameDB {
         self.peers.keys().copied().collect()
     }
 
+    #[must_use]
+    pub fn contains_peer(&self, addr: &SocketAddr) -> bool {
+        self.peers.contains_key(addr)
+    }
+
     #[must_use]
     pub fn peers_with_game(&self, game_id: &str) -> Vec<SocketAddr> {
         self.peers
@@ -1816,26 +1821,43 @@ async fn run_peer_discovery(
 ) {
     log::info!("Starting peer discovery task");
 
-    loop {
+    let service_type = LANSPREAD_SERVICE_TYPE.to_string();
-        let ignored_addr = { *local_peer_addr.read().await };
-        let discovery_result = discover_service(LANSPREAD_SERVICE_TYPE, ignored_addr);
 
-        match discovery_result {
+    loop {
-            Ok(peer_addr) => {
+        let (addr_tx, mut addr_rx) = tokio::sync::mpsc::unbounded_channel();
+        let service_type_clone = service_type.clone();
+
+        let worker_handle = tokio::task::spawn_blocking(move || -> eyre::Result<()> {
+            let browser = MdnsBrowser::new(&service_type_clone)?;
+            loop {
+                if let Some(addr) = browser.next_address(None)? {
+                    if addr_tx.send(addr).is_err() {
+                        log::debug!("Peer discovery consumer dropped; stopping worker");
+                        break;
+                    }
+                } else {
+                    log::warn!("mDNS browser closed; stopping peer discovery worker");
+                    break;
+                }
+            }
+            Ok(())
+        });
+
+        while let Some(peer_addr) = addr_rx.recv().await {
             let is_self = {
                 let guard = local_peer_addr.read().await;
                 guard.as_ref().is_some_and(|addr| *addr == peer_addr)
             };
+
             if is_self {
                 log::trace!("Ignoring self advertisement at {peer_addr}");
-                } else {
+                continue;
-                    log::info!("Discovered peer at: {peer_addr}");
+            }
 
-                    // Add peer to database
             let is_new_peer = {
                 let mut db = peer_game_db.write().await;
-                        let peer_addresses = db.get_peer_addresses();
+                if db.contains_peer(&peer_addr) {
-                        if peer_addresses.contains(&peer_addr) {
+                    db.update_last_seen(&peer_addr);
                     false
                 } else {
                     db.add_peer(peer_addr);
@@ -1844,29 +1866,22 @@ async fn run_peer_discovery(
             };
 
             if is_new_peer {
-                        // Notify UI about new peer
+                log::info!("Discovered peer at: {peer_addr}");
+
                 if let Err(e) = tx_notify_ui.send(PeerEvent::PeerDiscovered(peer_addr)) {
                     log::error!("Failed to send PeerDiscovered event: {e}");
                 }
 
-                        // Send updated peer count
+                let current_peer_count = { peer_game_db.read().await.get_peer_addresses().len() };
-                        let current_peer_count =
+                if let Err(e) = tx_notify_ui.send(PeerEvent::PeerCountUpdated(current_peer_count)) {
-                            { peer_game_db.read().await.get_peer_addresses().len() };
-                        if let Err(e) =
-                            tx_notify_ui.send(PeerEvent::PeerCountUpdated(current_peer_count))
-                        {
                     log::error!("Failed to send PeerCountUpdated event: {e}");
                 }
 
-                        // Request games from this peer
                 let tx_notify_ui_clone = tx_notify_ui.clone();
                 let peer_game_db_clone = peer_game_db.clone();
                 tokio::spawn(async move {
-                            if let Err(e) = request_games_from_peer(
+                    if let Err(e) =
-                                peer_addr,
+                        request_games_from_peer(peer_addr, tx_notify_ui_clone, peer_game_db_clone)
-                                tx_notify_ui_clone,
-                                peer_game_db_clone,
-                            )
                             .await
                     {
                         log::error!("Failed to request games from peer {peer_addr}: {e}");
@@ -1874,15 +1889,21 @@ async fn run_peer_discovery(
                 });
             }
         }
+
+        match worker_handle.await {
+            Ok(Ok(())) => {
+                log::warn!("Peer discovery worker exited; restarting shortly");
+            }
+            Ok(Err(e)) => {
+                log::error!("Peer discovery worker failed: {e}");
             }
             Err(e) => {
-                log::debug!("Peer discovery error: {e}");
+                log::error!("Peer discovery worker join error: {e}");
+            }
+        }
+
         tokio::time::sleep(Duration::from_secs(5)).await;
     }
-        }
-        // Wait before next discovery cycle
-        tokio::time::sleep(Duration::from_secs(10)).await;
-    }
 }
 
 async fn request_games_from_peer(