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Fix issue where the second send fails on linux when using UDP. #185

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Fix issue where the second send fails on linux when using UDP. #185

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10 changes: 9 additions & 1 deletion crates/ergot/src/interface_manager/profiles/direct_edge/tokio_udp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
//! This is useful for std based devices/applications that can directly connect to a DirectRouter
//! using a udp connection.

use std::io::ErrorKind;
use std::sync::Arc;

use crate::{
Expand Down Expand Up @@ -181,7 +182,14 @@ async fn tx_worker(tx: Arc<UdpSocket>, rx: FramedConsumer<StdQueue>, closer: Arc
let res = tx.send(&frame).await;
frame.release();
if let Err(e) = res {
error!("Tx Error. socket: {:?}, error: {:?}", tx, e);
match e.kind() {
// On Linux, the /SECOND/ `send` will cause a `ConnectionRefused` error when there
// is nothing listening and the source/destination are on the same host.
ErrorKind::ConnectionRefused => {},
Comment on lines +186 to +188
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@Darksonn Darksonn Jan 19, 2026

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There's no guarantee it happens on the second send. See the Tokio issue.

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@hydra hydra Jan 26, 2026

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Ok, yes, so perhaps the wording should be:

On Linux, /LATER/ calls to send /MAY/ cause a ConnectionRefused error when there is nothing listening and the source/destination are on the same host.

Thoughts? Improvements?

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@okhsunrog okhsunrog Mar 17, 2026

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This looks good to me. The rewording you proposed looks correct, just needs to be pushed.
Otherwise LGTM.

_ => {
error!("Tx Error. socket: {:?}, error: {:?}", tx, e);
}
}
}
}
// TODO: GC waker?
Expand Down
12 changes: 10 additions & 2 deletions crates/ergot/src/interface_manager/profiles/direct_router/tokio_udp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@
//!
//! This implementation can be used to connect to a number of direct edge UDP devices.

use std::io::ErrorKind;
use crate::logging::{debug, error, info, trace, warn};
use bbq2::{prod_cons::framed::FramedConsumer, traits::bbqhdl::BbqHandle};
use maitake_sync::WaitQueue;
Expand Down Expand Up @@ -70,8 +71,15 @@ impl TxWorker {
let res = self.tx.send(&frame).await;
frame.release();
if let Err(e) = res {
error!("Tx Error. socket: {:?}, error: {:?}", self.tx, e);
break;
match e.kind() {
// On Linux, the SECOND `send` will cause a `ConnectionRefused` error when there
// is nothing listening and the source/destination are on the same host.
ErrorKind::ConnectionRefused => {},
_ => {
error!("Tx Error. socket: {:?}, error: {:?}", self.tx, e);
break;
}
}
}
}
}
Expand Down