Ignore ENOBUFS when writing to VM's socket (#18)

* Ignore ENOBUFS when writing to VM's socket

* Hint the into() target type to the compiler to fix the build error

* Fix Clippy warnings

lib/poller.rs

@@ -52,8 +52,14 @@ impl Poller {
         self.poller
             .wait(&mut self.events, Some(Duration::from_millis(100)))?;
 
-        let vm_readable = self.events.iter().any(|ev| ev.key == EventKey::VM.into());
-        let host_readable = self.events.iter().any(|ev| ev.key == EventKey::Host.into());
+        let vm_readable = self
+            .events
+            .iter()
+            .any(|ev| ev.key == Into::<usize>::into(EventKey::VM));
+        let host_readable = self
+            .events
+            .iter()
+            .any(|ev| ev.key == Into::<usize>::into(EventKey::Host));
 
         Ok((vm_readable, host_readable))
     }

lib/proxy/host.rs

@@ -16,10 +16,21 @@ impl Proxy {
             self.snoop(frame);
         }
 
-        self.vm
-            .write(frame.as_ref())
-            .map(|_| ())
-            .context("failed to write to the VM")
+        match self.vm.write(frame.as_ref()) {
+            Ok(_) => Ok(()),
+            Err(err) => {
+                if let Some(libc::ENOBUFS) = err.raw_os_error() {
+                    sentry::capture_message(
+                        "No buffer space available in VM's socket",
+                        sentry::Level::Warning,
+                    );
+
+                    return Ok(());
+                }
+
+                Err(err).context("failed to write to the VM")
+            }
+        }
     }
 
     fn allowed_from_host(&mut self, frame: &EthernetFrame<&[u8]>) -> Option<()> {

src/main.rs

@@ -60,7 +60,7 @@ fn main() -> ExitCode {
     // Enrich future events with Cirrus CI-specific tags
     if let Ok(tags) = env::var("CIRRUS_SENTRY_TAGS") {
         sentry::configure_scope(|scope| {
-            for (key, value) in tags.split(",").map(|tag| tag.split_once("=")).flatten() {
+            for (key, value) in tags.split(',').filter_map(|tag| tag.split_once('=')) {
                 scope.set_tag(key, value);
             }
         });