Ignore inactive network interfaces

src/client/discovery.rs

@@ -1,6 +1,7 @@
 use crate::api::TypedDevice;
 use crate::discovery::{
-    bind_socket, AlpacaPort, DEFAULT_DISCOVERY_PORT, DISCOVERY_ADDR_V6, DISCOVERY_MSG,
+    bind_socket, get_active_interfaces, AlpacaPort, DEFAULT_DISCOVERY_PORT, DISCOVERY_ADDR_V6,
+    DISCOVERY_MSG,
 };
 use futures::StreamExt;
 use netdev::interface::InterfaceType;
@@ -168,7 +169,7 @@ impl Client {
     #[tracing::instrument(level = "error")]
     pub async fn bind(self) -> eyre::Result<BoundClient> {
         let socket = bind_socket((Ipv6Addr::UNSPECIFIED, 0)).await?;
-        let interfaces = tokio::task::spawn_blocking(netdev::get_interfaces).await?;
+        let interfaces = tokio::task::spawn_blocking(|| get_active_interfaces().collect()).await?;
         Ok(BoundClient {
             client: self,
             socket,

src/discovery.rs

@@ -14,6 +14,12 @@ pub(crate) struct AlpacaPort {
     pub(crate) alpaca_port: u16,
 }
 
+pub(crate) fn get_active_interfaces() -> impl Iterator<Item = Interface> {
+    netdev::get_interfaces()
+        .into_iter()
+        .filter(Interface::is_running)
+}
+
 #[tracing::instrument(level = "trace")]
 pub(crate) async fn bind_socket(
     addr: impl Into<SocketAddr> + std::fmt::Debug + Send,
@@ -67,6 +73,7 @@ pub(crate) async fn bind_socket(
 pub use crate::client::{BoundDiscoveryClient, DiscoveryClient};
 #[cfg(feature = "server")]
 pub use crate::server::{BoundDiscoveryServer, DiscoveryServer};
+use netdev::Interface;
 #[cfg(windows)]
 use std::os::windows::prelude::AsRawSocket;
 
@@ -136,7 +143,7 @@ mod tests {
                     .chain(DEFAULT_INTF.ipv6.iter().map(|net| (net.addr.into(), expected_addrs.default_intf_v6)));
 
                 for (addr, expected) in expected_addrs {
-                    eyre::ensure!(addrs.contains(&addr) == expected, "Address {addr} was{not} expected", addr = addr, not = if expected { "" } else { " not" });
+                    eyre::ensure!(addrs.contains(&addr) == expected, "Address {addr} was{not} expected", not = if expected { "" } else { " not" });
                 }
 
                 Ok(())

src/server/discovery.rs

@@ -1,5 +1,7 @@
 use super::DEFAULT_DISCOVERY_PORT;
-use crate::discovery::{bind_socket, AlpacaPort, DISCOVERY_ADDR_V6, DISCOVERY_MSG};
+use crate::discovery::{
+    bind_socket, get_active_interfaces, AlpacaPort, DISCOVERY_ADDR_V6, DISCOVERY_MSG,
+};
 use netdev::Interface;
 use std::net::{IpAddr, Ipv6Addr, SocketAddr};
 use tokio::net::UdpSocket;
@@ -23,22 +25,20 @@ fn join_multicast_group(socket: &UdpSocket, intf: &Interface) {
 
 #[tracing::instrument(level = "debug", ret, skip(socket))]
 fn join_multicast_groups(socket: &UdpSocket, listen_addr: Ipv6Addr) {
-    let interfaces = netdev::get_interfaces();
     if listen_addr.is_unspecified() {
         // If it's [::], join multicast on every available interface with IPv6 support.
-        for intf in interfaces {
+        for intf in get_active_interfaces() {
             if !intf.ipv6.is_empty() {
                 join_multicast_group(socket, &intf);
             }
         }
     } else {
         // If it's a specific address, find corresponding interface and join multicast on it.
-        let intf = interfaces
-            .iter()
+        let intf = get_active_interfaces()
             .find(|intf| intf.ipv6.iter().any(|net| net.addr == listen_addr))
             .expect("internal error: couldn't find the interface of an already bound socket");
 
-        join_multicast_group(socket, intf);
+        join_multicast_group(socket, &intf);
     }
 }