Implement `is_offline` for Linux

2 files changed, 78 insertions, 1 deletions

diff --git a/talpid-core/src/offline/linux.rs b/talpid-core/src/offline/linux.rs
new file mode 100644
index 0000000000..4b76120fb4
--- /dev/null
+++ b/talpid-core/src/offline/linux.rs
@@ -0,0 +1,73 @@
+extern crate iproute2;
+extern crate rtnetlink;
+
+use error_chain::ChainedError;
+use futures::{future::Either, sync::mpsc::UnboundedSender, Future};
+use log::warn;
+
+use self::iproute2::Link;
+use self::rtnetlink::LinkLayerType;
+
+use tunnel_state_machine::TunnelCommand;
+
+error_chain! {
+    errors {
+        GetLinksError {
+            description("Failed to get list of IP links")
+        }
+        NetlinkConnectionError {
+            description("Failed to connect to netlink socket")
+        }
+        NetlinkError {
+            description("Error while communicating on the netlink socket")
+        }
+        NetlinkDisconnected {
+            description("Netlink connection has unexpectedly disconnected")
+        }
+    }
+}
+
+pub struct MonitorHandle;
+
+pub fn spawn_monitor(_sender: UnboundedSender<TunnelCommand>) -> Result<MonitorHandle> {
+    Ok(MonitorHandle)
+}
+
+pub fn is_offline() -> bool {
+    check_if_offline().unwrap_or_else(|error| {
+        let chained_error = error.chain_err(|| "Failed to check for internet connection");
+        warn!("{}", chained_error.display_chain());
+        false
+    })
+}
+
+fn check_if_offline() -> Result<bool> {
+    Ok(list_links_providing_connectivity()?.next().is_none())
+}
+
+fn list_links_providing_connectivity() -> Result<impl Iterator<Item = Link>> {
+    Ok(list_links()?.into_iter().filter(link_provides_connectivity))
+}
+
+fn link_provides_connectivity(link: &Link) -> bool {
+    // Some tunnels have the link layer type set to None
+    link.link_layer_type() != LinkLayerType::Loopback
+        && link.link_layer_type() != LinkLayerType::None
+        && link.flags().is_running()
+}
+
+fn list_links() -> Result<Vec<Link>> {
+    let (connection, connection_handle) =
+        iproute2::new_connection().chain_err(|| ErrorKind::NetlinkConnectionError)?;
+    let links_request = connection_handle.link().get().execute();
+
+    match connection.select2(links_request).wait() {
+        Ok(Either::A(_)) => bail!(ErrorKind::NetlinkDisconnected),
+        Ok(Either::B((links, _))) => Ok(links),
+        Err(Either::A((error, _))) => Err(Error::with_chain(error, ErrorKind::NetlinkError)),
+        Err(Either::B((error, _))) => Err(Error::with_chain(
+            failure::Fail::compat(error),
+            ErrorKind::GetLinksError,
+        )),
+    }
+}
diff --git a/talpid-core/src/offline/mod.rs b/talpid-core/src/offline/mod.rs
index 38ebc3fb1e..e73de2efc1 100644
--- a/talpid-core/src/offline/mod.rs
+++ b/talpid-core/src/offline/mod.rs
@@ -9,7 +9,11 @@ mod imp;
 #[path = "windows.rs"]
 mod imp;
 
-#[cfg(not(any(windows, target_os = "macos")))]
+#[cfg(target_os = "linux")]
+#[path = "linux.rs"]
+mod imp;
+
+#[cfg(not(any(windows, target_os = "linux", target_os = "macos")))]
 #[path = "dummy.rs"]
 mod imp;