-// The "objc2" project aims to provide bindings for all frameworks but Network.framework
-// isn't ready yet so let's kick it old-school
-
-struct nw_path_monitor;
-type nw_path_monitor_t = *mut nw_path_monitor;
-struct nw_path;
-type nw_path_t = *mut nw_path;
-struct dispatch_queue;
-type dispatch_queue_t = *mut dispatch_queue;
-const QOS_CLASS_BACKGROUND: usize = 0x09;
-
-#[link(name = "Network", kind = "framework")]
-extern "C" {
-    fn nw_path_monitor_create() -> nw_path_monitor_t;
-    fn nw_path_monitor_set_update_handler(
-        monitor: nw_path_monitor_t,
-        update_handler: &Block<dyn Fn(nw_path_t)>,
-    );
-    fn nw_path_monitor_set_queue(monitor: nw_path_monitor_t, queue: dispatch_queue_t);
-    fn nw_path_monitor_start(monitor: nw_path_monitor_t);
-    fn nw_path_monitor_cancel(monitor: nw_path_monitor_t);
-
-    fn dispatch_get_global_queue(identifier: usize, flag: usize) -> dispatch_queue_t;
-}
-
-#[cfg(test)]
-mod test {
-    use super::list_interfaces;
-
-    #[test]
-    fn list() {
-        let ifaces = list_interfaces().unwrap();
-        println!("{:?}", ifaces);
+fn format_mac(bytes: &[u8]) -> Result<String, Error> {
+    let mut mac = String::with_capacity(bytes.len() * 3);
+    for (i, b) in bytes.iter().enumerate() {
+        if i != 0 {
+            write!(mac, ":").map_err(|_| Error::FormatMacAddress)?;
+        }
+        write!(mac, "{:02X}", b).map_err(|_| Error::FormatMacAddress)?;