From d8800a37f24cd175f01fcfa52dea9a116307f7c4 Mon Sep 17 00:00:00 2001
From: Joakim Hulthe <joakim.hulthe@mullvad.net>
Date: Wed, 16 Apr 2025 18:31:47 +0200
Subject: Split masque-proxy connection_task into two

---
 mullvad-masque-proxy/src/server/mod.rs | 87 ++++++++++++++++++----------------
 1 file changed, 46 insertions(+), 41 deletions(-)

diff --git a/mullvad-masque-proxy/src/server/mod.rs b/mullvad-masque-proxy/src/server/mod.rs
index 21d497bbc4..4ad4b64c8d 100644
--- a/mullvad-masque-proxy/src/server/mod.rs
+++ b/mullvad-masque-proxy/src/server/mod.rs
@@ -183,13 +183,10 @@ impl Server {
         let (client_tx, client_rx) = mpsc::channel(MAX_INFLIGHT_PACKETS);
         let (send_tx, send_rx) = mpsc::channel(MAX_INFLIGHT_PACKETS);
 
-        let mut connection_task = task::spawn(connection_task(
-            stream_id,
-            connection,
-            quinn_conn.clone(),
-            send_rx,
-            client_tx,
-        ));
+        let mut connection_rx_task =
+            task::spawn(connection_rx_task(stream_id, connection, client_tx));
+        let mut connection_tx_task =
+            task::spawn(connection_tx_task(stream_id, quinn_conn.clone(), send_rx));
         let mut proxy_rx_task = task::spawn(proxy_rx_task(
             stream_id,
             quinn_conn,
@@ -201,59 +198,67 @@ impl Server {
         let mut proxy_tx_task = task::spawn(proxy_tx_task(udp_socket, client_rx));
 
         select! {
-            _ = &mut connection_task => {}
+            _ = &mut connection_rx_task => {}
+            _ = &mut connection_tx_task => {}
             _ = &mut proxy_rx_task   => {}
             _ = &mut proxy_tx_task   => {}
         }
 
-        connection_task.abort();
+        connection_rx_task.abort();
+        connection_tx_task.abort();
         proxy_rx_task.abort();
         proxy_tx_task.abort();
 
         // TODO: stream.finish()?
     }
 }
+async fn connection_tx_task(
+    stream_id: StreamId,
+    quinn_conn: quinn::Connection,
+    mut send_rx: mpsc::Receiver<Bytes>,
+) -> anyhow::Result<()> {
+    loop {
+        let outgoing_packet = send_rx.recv().await;
+        let Some(outgoing_packet) = outgoing_packet else {
+            break; // sender is gone
+        };
+
+        let mut buf = BytesMut::new();
+        (VarInt::from(stream_id) / 4).encode(&mut buf);
+        buf.put(outgoing_packet);
+        quinn_conn
+            .send_datagram_wait(buf.freeze())
+            .await
+            .context("Error sending QUIC datagram to client")?;
+    }
+
+    Ok(())
+}
 
 /// Forward packets from `send_rx` to `connection`, and from `connection` to `client_tx`.
-async fn connection_task(
+async fn connection_rx_task(
     stream_id: StreamId,
     mut connection: Connection<h3_quinn::Connection, Bytes>,
-    quinn_conn: quinn::Connection,
-    mut send_rx: mpsc::Receiver<Bytes>,
     client_tx: mpsc::Sender<Datagram>,
 ) -> anyhow::Result<()> {
     loop {
         // TODO: split into two tasks
-        tokio::select! {
-            outgoing_packet = send_rx.recv() => {
-                let Some(outgoing_packet) = outgoing_packet else {
-                    break; // sender is gone
-                };
-
-                let mut buf = BytesMut::new();
-                (VarInt::from(stream_id) / 4).encode(&mut buf);
-                buf.put(outgoing_packet);
-                quinn_conn
-                    .send_datagram_wait(buf.freeze())
-                    .await
-                    .context("Error sending QUIC datagram to client")?;
-            }
-            incoming_packet = connection.read_datagram() => match incoming_packet {
-                Ok(Some(received_packet)) => {
-                    ensure!(
-                        received_packet.stream_id() == stream_id,
-                        "Received unexpected stream ID from client",
-                    );
-
-                    if client_tx.send(received_packet).await.is_err() {
-                        break; // receiver is gone
-                    }
-                }
-                Ok(None) => break, // EOF
-                Err(err) => {
-                    return Err(err).context("Error reading QUIC datagram from client");
+        let incoming_packet = connection.read_datagram().await;
+        match incoming_packet {
+            Ok(Some(received_packet)) => {
+                ensure!(
+                    received_packet.stream_id() == stream_id,
+                    "Received unexpected stream ID from client",
+                );
+
+                if client_tx.send(received_packet).await.is_err() {
+                    break; // receiver is gone
                 }
-            },
+            }
+            Ok(None) => break, // EOF
+            Err(err) => {
+                return Err(err).context("Error reading QUIC datagram from client");
+            }
         }
     }
 
-- 
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