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Prevent datagram races by never reusing device IDs

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This commit is contained in:
Jan Trefil 2024-07-21 16:21:02 +02:00
parent c4bad45532
commit f1c11f0dc1
1 changed files with 10 additions and 7 deletions
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17
rkvm-server/src/server.rs
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@ -64,7 +64,8 @@ pub async fn run(
});
let mut monitor = Monitor::new();
let mut devices = Slab::<Device>::new();
let mut id = 0usize;
let mut devices = HashMap::<usize, Device>::new();
let mut clients = Slab::<(Sender<_>, SocketAddr)>::new();
let mut current = 0;
let mut previous = 0;
@ -94,7 +95,7 @@ pub async fn run(
let init_updates = devices
.iter()
.map(|(id, device)| Update::CreateDevice {
id,
id: *id,
name: device.name.clone(),
version: device.version,
vendor: device.vendor,
@ -127,8 +128,9 @@ pub async fn run(
interceptor = monitor.read() => {
let mut interceptor = interceptor.map_err(Error::Input)?;
id = id.checked_add(1).unwrap();
let name = interceptor.name().to_owned();
let id = devices.vacant_key();
let version = interceptor.version();
let vendor = interceptor.vendor();
let product = interceptor.product();
@ -155,7 +157,7 @@ pub async fn run(
}
let (interceptor_sender, mut interceptor_receiver) = mpsc::channel(32);
devices.insert(Device {
devices.insert(id, Device {
name,
version,
vendor,
@ -197,7 +199,7 @@ pub async fn run(
}
});
let device = &devices[id];
let device = &devices[&id];
tracing::info!(
id = %id,
@ -267,8 +269,9 @@ pub async fn run(
// In this scenario, the interceptor task is sending events to the main task,
// while the main task is simultaneously sending events back to the interceptor.
// This creates a classic deadlock situation where both tasks are waiting for each other.
let sender = &devices[&id].sender;
for event in events {
match devices[id].sender.try_send(event) {
match sender.try_send(event) {
Ok(()) | Err(TrySendError::Closed(_)) => {},
Err(TrySendError::Full(_)) => return Err(Error::Overflow),
}
@ -291,7 +294,7 @@ pub async fn run(
for (_, (sender, _)) in &clients {
let _ = sender.send(Update::DestroyDevice { id }).await;
}
devices.remove(id);
devices.remove(&id);
tracing::info!(id = %id, "Destroyed device");
}