Improve errors

[netwatcher] / src / lib.rs

diff --git a/src/lib.rs b/src/lib.rs
index 47c5ae11957466f7e233e0f2690105d431fad154..495b9e64f5098aadb9b1d7d8b8d7f4a4603f2a40 100644 (file)
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,19 +4,25 @@ use std::{
     ops::Sub,
 };
 
+mod error;
+
 #[cfg_attr(windows, path = "list_win.rs")]
-#[cfg_attr(target_vendor = "apple", path = "list_mac.rs")]
+#[cfg_attr(unix, path = "list_unix.rs")]
 mod list;
 
 #[cfg_attr(windows, path = "watch_win.rs")]
 #[cfg_attr(target_vendor = "apple", path = "watch_mac.rs")]
+#[cfg_attr(
+    any(target_os = "linux", target_os = "android"),
+    path = "watch_linux.rs"
+)]
 mod watch;
 
-#[cfg(target_vendor = "apple")]
-mod util;
-
 type IfIndex = u32;
 
+pub use error::Error;
+
+/// Information about one network interface at a point in time.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Interface {
     pub index: u32,
@@ -26,6 +32,7 @@ pub struct Interface {
 }
 
 impl Interface {
+    /// Helper to iterate over only the IPv4 addresses on this interface.
     pub fn ipv4_ips(&self) -> impl Iterator<Item = &Ipv4Addr> {
         self.ips.iter().filter_map(|ip| match ip {
             IpAddr::V4(v4) => Some(v4),
@@ -33,6 +40,7 @@ impl Interface {
         })
     }
 
+    /// Helper to iterate over only the IPv6 addresses on this interface.
     pub fn ipv6_ips(&self) -> impl Iterator<Item = &Ipv6Addr> {
         self.ips.iter().filter_map(|ip| match ip {
             IpAddr::V4(_) => None,
@@ -41,12 +49,17 @@ impl Interface {
     }
 }
 
+/// Information delivered via callback when a network interface change is detected.
+///
+/// This contains up-to-date information about all interfaces, plus a diff which
+/// details which interfaces and IP addresses have changed since the last callback.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Update {
     pub interfaces: HashMap<IfIndex, Interface>,
     pub diff: UpdateDiff,
 }
 
+/// What changed between one `Update` and the next.
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
 pub struct UpdateDiff {
     pub added: Vec<IfIndex>,
@@ -54,6 +67,7 @@ pub struct UpdateDiff {
     pub modified: HashMap<IfIndex, InterfaceDiff>,
 }
 
+/// What changed within a single interface between updates, if it was present in both.
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
 pub struct InterfaceDiff {
     pub hw_addr_changed: bool,
@@ -61,12 +75,6 @@ pub struct InterfaceDiff {
     pub addrs_removed: Vec<IpAddr>,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum Error {
-    // TODO: handle all cases with proper sources
-    Internal,
-}
-
 #[derive(Default, PartialEq, Eq)]
 struct List(HashMap<IfIndex, Interface>);
 
@@ -113,14 +121,39 @@ impl List {
     }
 }
 
+/// A handle to keep alive as long as you wish to receive callbacks.
+///
+/// If the callback is executing at the time the handle is dropped, drop will block until
+/// the callback is finished and it's guaranteed that it will not be called again.
+///
+/// Do not drop the handle from within the callback itself. It will probably deadlock.
 pub struct WatchHandle {
     _inner: watch::WatchHandle,
 }
 
+/// Retrieve information about all enabled network interfaces and their IP addresses.
+///
+/// This is a once-off operation. If you want to detect changes over time, see `watch_interfaces`.
 pub fn list_interfaces() -> Result<HashMap<IfIndex, Interface>, Error> {
     list::list_interfaces().map(|list| list.0)
 }
 
-pub fn watch_interfaces<F: FnMut(Update) + 'static>(callback: F) -> Result<WatchHandle, Error> {
+/// Retrieve interface information and watch for changes, which will be delivered via callback.
+///
+/// If setting up the watch is successful, this returns a `WatchHandle` which must be kept for
+/// as long as the provided callback should operate.
+///
+/// The callback will fire once immediately with an initial interface list, and a diff as if
+/// there were originally no interfaces present.
+///
+/// This function will return an error if there is a problem configuring the watcher, or if there
+/// is an error retrieving the initial interface list.
+///
+/// We assume that if listing the interfaces worked the first time, then it will continue to work
+/// for as long as the watcher is running. If listing interfaces begins to fail later, those
+/// failures will be swallowed and the callback will not be called for that change event.
+pub fn watch_interfaces<F: FnMut(Update) + Send + 'static>(
+    callback: F,
+) -> Result<WatchHandle, Error> {
     watch::watch_interfaces(callback).map(|handle| WatchHandle { _inner: handle })
 }