net: improve error handling for backend creation

With the new API, as we're actively participating in opening the
connection to the network proxy, the creation of the virtio-net backend
may fail. Avoid using "unwrap" and fail gracefully on device activation
instead.

Signed-off-by: Sergio Lopez <[email protected]>

Author: slp

src/devices/src/virtio/net/device.rs

@@ -8,7 +8,7 @@ use crate::legacy::IrqChip;
 use crate::virtio::net::{Error, Result};
 use crate::virtio::net::{QUEUE_SIZES, RX_INDEX, TX_INDEX};
 use crate::virtio::queue::Error as QueueError;
-use crate::virtio::{ActivateResult, DeviceState, Queue, VirtioDevice, TYPE_NET};
+use crate::virtio::{ActivateError, ActivateResult, DeviceState, Queue, VirtioDevice, TYPE_NET};
 use crate::Error as DeviceError;
 
 use super::backend::{ReadError, WriteError};
@@ -223,7 +223,8 @@ impl VirtioDevice for Net {
             .iter()
             .map(|e| e.try_clone().unwrap())
             .collect();
-        let worker = NetWorker::new(
+
+        match NetWorker::new(
             self.queues.clone(),
             queue_evts,
             self.interrupt_status.clone(),
@@ -232,11 +233,20 @@ impl VirtioDevice for Net {
             self.irq_line,
             mem.clone(),
             self.cfg_backend.clone(),
-        );
-        worker.run();
-
-        self.device_state = DeviceState::Activated(mem);
-        Ok(())
+        ) {
+            Ok(worker) => {
+                worker.run();
+                self.device_state = DeviceState::Activated(mem);
+                Ok(())
+            }
+            Err(err) => {
+                error!(
+                    "Error activating virtio-net ({}) backend: {err:?}",
+                    self.id()
+                );
+                Err(ActivateError::BadActivate)
+            }
+        }
     }
 
     fn is_activated(&self) -> bool {

src/devices/src/virtio/net/worker.rs

@@ -1,4 +1,5 @@
 use crate::legacy::IrqChip;
+use crate::virtio::net::backend::ConnectError;
 #[cfg(target_os = "linux")]
 use crate::virtio::net::tap::Tap;
 use crate::virtio::net::unixgram::Unixgram;
@@ -52,27 +53,27 @@ impl NetWorker {
         irq_line: Option<u32>,
         mem: GuestMemoryMmap,
         cfg_backend: VirtioNetBackend,
-    ) -> Self {
+    ) -> Result<Self, ConnectError> {
         let backend = match cfg_backend {
             VirtioNetBackend::UnixstreamFd(fd) => {
                 Box::new(Unixstream::new(fd)) as Box<dyn NetBackend + Send>
             }
             VirtioNetBackend::UnixstreamPath(path) => {
-                Box::new(Unixstream::open(path).unwrap()) as Box<dyn NetBackend + Send>
+                Box::new(Unixstream::open(path)?) as Box<dyn NetBackend + Send>
             }
             VirtioNetBackend::UnixgramFd(fd) => {
                 Box::new(Unixgram::new(fd)) as Box<dyn NetBackend + Send>
             }
             VirtioNetBackend::UnixgramPath(path, vfkit_magic) => {
-                Box::new(Unixgram::open(path, vfkit_magic).unwrap()) as Box<dyn NetBackend + Send>
+                Box::new(Unixgram::open(path, vfkit_magic)?) as Box<dyn NetBackend + Send>
             }
             #[cfg(target_os = "linux")]
             VirtioNetBackend::Tap(tap_name) => {
-                Box::new(Tap::new(tap_name).unwrap()) as Box<dyn NetBackend + Send>
+                Box::new(Tap::new(tap_name)?) as Box<dyn NetBackend + Send>
             }
         };
 
-        Self {
+        Ok(Self {
             queues,
             queue_evts,
             interrupt_status,
@@ -90,7 +91,7 @@ impl NetWorker {
             tx_frame_buf: [0u8; MAX_BUFFER_SIZE],
             tx_frame_len: 0,
             tx_iovec: Vec::with_capacity(QUEUE_SIZE as usize),
-        }
+        })
     }
 
     pub fn run(self) {