Add interface/mtu change listener

3 files changed, 47 insertions, 0 deletions

diff --git a/talpid-routing/src/unix/macos/data.rs b/talpid-routing/src/unix/macos/data.rs
index a5e8a49efd..5ac83d0885 100644
--- a/talpid-routing/src/unix/macos/data.rs
+++ b/talpid-routing/src/unix/macos/data.rs
@@ -634,6 +634,10 @@ impl Interface {
         self.header.ifm_index
     }
 
+    pub fn mtu(&self) -> u32 {
+        self.header.ifm_data.ifi_mtu
+    }
+
     fn from_byte_buffer(buffer: &[u8]) -> Result<Self> {
         const INTERFACE_MESSAGE_HEADER_SIZE: usize = std::mem::size_of::<libc::if_msghdr>();
         if INTERFACE_MESSAGE_HEADER_SIZE > buffer.len() {
diff --git a/talpid-routing/src/unix/macos/mod.rs b/talpid-routing/src/unix/macos/mod.rs
index 141b8c06d3..85a020ba79 100644
--- a/talpid-routing/src/unix/macos/mod.rs
+++ b/talpid-routing/src/unix/macos/mod.rs
@@ -90,6 +90,7 @@ pub struct RouteManagerImpl {
     v6_default_route: Option<interface::DefaultRoute>,
     update_trigger: BurstGuard,
     default_route_listeners: Vec<mpsc::UnboundedSender<DefaultRouteEvent>>,
+    interface_change_listeners: Vec<mpsc::UnboundedSender<super::InterfaceEvent>>,
     check_default_routes_restored: Pin<Box<dyn FusedStream<Item = ()> + Send>>,
     unhandled_default_route_changes: bool,
     primary_interface_monitor: interface::PrimaryInterfaceMonitor,
@@ -127,6 +128,7 @@ impl RouteManagerImpl {
             v6_default_route: None,
             update_trigger,
             default_route_listeners: vec![],
+            interface_change_listeners: vec![],
             check_default_routes_restored: Box::pin(futures::stream::pending()),
             unhandled_default_route_changes: false,
             primary_interface_monitor,
@@ -227,6 +229,13 @@ impl RouteManagerImpl {
                                 log::error!("Failed to clean up rotues: {err}");
                             }
                         },
+
+                        Some(RouteManagerCommand::NewInterfaceChangeListener(tx)) => {
+                            let (events_tx, events_rx) = mpsc::unbounded();
+                            self.interface_change_listeners.push(events_tx);
+                            let _ = tx.send(events_rx);
+                        }
+
                         Some(RouteManagerCommand::RefreshRoutes) => {
                             if let Err(error) = self.refresh_routes().await {
                                 log::error!("Failed to refresh routes: {error}");
@@ -377,6 +386,20 @@ impl RouteManagerImpl {
             Ok(RouteSocketMessage::AddAddress(_) | RouteSocketMessage::DeleteAddress(_)) => {
                 self.update_trigger.trigger();
             }
+            Ok(RouteSocketMessage::Interface(iface)) => {
+                let Ok(mtu) = u16::try_from(iface.mtu()) else {
+                    log::warn!("Invalid mtu for interface: {}", iface.index());
+                    return;
+                };
+
+                self.interface_change_listeners.retain(|tx| {
+                    tx.unbounded_send(super::InterfaceEvent {
+                        interface_index: iface.index(),
+                        mtu,
+                    })
+                    .is_ok()
+                });
+            }
             // ignore all other message types
             Ok(_) => {}
             Err(err) => {
diff --git a/talpid-routing/src/unix/mod.rs b/talpid-routing/src/unix/mod.rs
index 044a09433a..d257140f7e 100644
--- a/talpid-routing/src/unix/mod.rs
+++ b/talpid-routing/src/unix/mod.rs
@@ -118,10 +118,18 @@ pub(crate) enum RouteManagerCommand {
     RefreshRoutes,
     NewDefaultRouteListener(oneshot::Sender<mpsc::UnboundedReceiver<DefaultRouteEvent>>),
     GetDefaultRoutes(oneshot::Sender<(Option<DefaultRoute>, Option<DefaultRoute>)>),
+    NewInterfaceChangeListener(oneshot::Sender<mpsc::UnboundedReceiver<InterfaceEvent>>),
     /// Return gateway for V4 and V6
     GetDefaultGateway(oneshot::Sender<(Option<Gateway>, Option<Gateway>)>),
 }
 
+/// Event that is sent when interface details may have changed for some interface.
+#[cfg(target_os = "macos")]
+pub struct InterfaceEvent {
+    pub interface_index: u16,
+    pub mtu: u16,
+}
+
 /// Event that is sent when a preferred non-tunnel default route is
 /// added or removed.
 #[cfg(target_os = "macos")]
@@ -227,6 +235,18 @@ impl RouteManagerHandle {
         response_rx.await.map_err(|_| Error::ManagerChannelDown)
     }
 
+    /// Listen for interface changes.
+    #[cfg(target_os = "macos")]
+    pub async fn interface_change_listener(
+        &self,
+    ) -> Result<impl Stream<Item = InterfaceEvent>, Error> {
+        let (response_tx, response_rx) = oneshot::channel();
+        self.tx
+            .unbounded_send(RouteManagerCommand::NewInterfaceChangeListener(response_tx))
+            .map_err(|_| Error::RouteManagerDown)?;
+        response_rx.await.map_err(|_| Error::ManagerChannelDown)
+    }
+
     /// Get default gateway
     #[cfg(target_os = "macos")]
     pub async fn get_default_gateway(&self) -> Result<(Option<Gateway>, Option<Gateway>), Error> {