From e81b6fa1fa9aa0f693619bcf22a7877512ff1fb4 Mon Sep 17 00:00:00 2001
From: Michael Bradley <michaelmbrad@gmail.com>
Date: Sun, 25 May 2025 12:28:32 -0400
Subject: [PATCH] Redo netcode error handling

No more panics :)
---
 src/net.rs | 122 +++++++++++++++++++++++++++++++++--------------------
 1 file changed, 77 insertions(+), 45 deletions(-)

diff --git a/src/net.rs b/src/net.rs
index 1055e92..3645944 100644
--- a/src/net.rs
+++ b/src/net.rs
@@ -1,18 +1,67 @@
 use std::{
     net::{Ipv6Addr, SocketAddr, UdpSocket},
-    thread,
+    thread::{JoinHandle, spawn},
 };
 
-use bevy::prelude::*;
+use bevy::{prelude::*, tasks::futures_lite::io};
 use crossbeam_channel::{Receiver, Sender, unbounded};
 
 use crate::game::seed::Seed;
 
-#[derive(Resource)]
-pub struct NetworkSend(Sender<(u64, SocketAddr)>);
+fn configure_socket(socket: &UdpSocket) -> io::Result<()> {
+    socket.set_read_timeout(None)?;
+    socket.set_write_timeout(None)?;
+    Ok(())
+}
+
+type NetworkMessage = (u64, SocketAddr);
+
+fn start_network_thread<M: Send + 'static>(
+    network_loop: fn(M, UdpSocket) -> Result,
+    messages: M,
+    socket: UdpSocket,
+) -> JoinHandle<Result> {
+    spawn(move || {
+        let result = network_loop(messages, socket);
+        match result {
+            Ok(()) => error!("Network thread: Loop returned without error?"),
+            Err(ref err) => error!("Network thread: {}", err),
+        };
+        result
+    })
+}
+
+fn network_send_loop(messages: Receiver<NetworkMessage>, socket: UdpSocket) -> Result {
+    loop {
+        let (message, address) = messages.recv()?;
+        socket.send_to(&message.to_le_bytes(), address)?;
+    }
+}
+
+fn network_receive_loop(messages: Sender<NetworkMessage>, socket: UdpSocket) -> Result {
+    loop {
+        let mut message = [0u8; 8];
+        let (len, address) = socket.recv_from(&mut message)?;
+        info!("Network thread: Received {len} bytes");
+        messages.try_send((u64::from_le_bytes(message), address))?;
+    }
+}
+
+fn setup_socket(port: u16) -> Result<(Sender<NetworkMessage>, Receiver<NetworkMessage>)> {
+    let socket = UdpSocket::bind((Ipv6Addr::LOCALHOST, port))?;
+    configure_socket(&socket)?;
+    let (send_inbound, receive_inbound) = unbounded();
+    start_network_thread(network_receive_loop, send_inbound, socket.try_clone()?);
+    let (send_outbound, receive_outbound) = unbounded();
+    start_network_thread(network_send_loop, receive_outbound, socket);
+    Ok((send_outbound, receive_inbound))
+}
 
 #[derive(Resource)]
-pub struct NetworkReceive(Receiver<(u64, SocketAddr)>);
+pub struct NetworkSend(Sender<NetworkMessage>);
+
+#[derive(Resource)]
+pub struct NetworkReceive(Receiver<NetworkMessage>);
 
 fn handle_network_io(
     receive: Res<NetworkReceive>,
@@ -31,6 +80,13 @@ fn handle_network_io(
     Ok(())
 }
 
+#[derive(States, Default, Debug, Clone, PartialEq, Eq, Hash)]
+enum NetworkState {
+    #[default]
+    SinglePlayer,
+    MultiPlayer,
+}
+
 pub struct NetIOPlugin {
     listen: u16,
     peer: Option<SocketAddr>,
@@ -44,51 +100,27 @@ impl NetIOPlugin {
 
 impl Plugin for NetIOPlugin {
     fn build(&self, app: &mut App) {
-        app.add_systems(FixedUpdate, handle_network_io);
+        app.init_state::<NetworkState>().add_systems(
+            FixedUpdate,
+            handle_network_io.run_if(in_state(NetworkState::MultiPlayer)),
+        );
 
-        let (send, receive) = match UdpSocket::bind((Ipv6Addr::LOCALHOST, self.listen)) {
-            Ok(socket) => {
-                socket.set_read_timeout(None).unwrap();
-                socket.set_write_timeout(None).unwrap();
-                let (send_outbound, receive_outbound) = unbounded::<(u64, SocketAddr)>();
-                let send_socket = socket.try_clone().unwrap();
-                thread::spawn(move || {
-                    loop {
-                        match receive_outbound.recv() {
-                            Ok((message, address)) => send_socket
-                                .send_to(&message.to_le_bytes(), address)
-                                .unwrap(),
-                            Err(err) => {
-                                error!("{err}");
-                                break;
-                            }
-                        };
+        match setup_socket(self.listen) {
+            Ok((send, receive)) => {
+                if let Some(socket) = self.peer {
+                    if let Err(err) = send.try_send((0, socket)) {
+                        warn!("Failed to send to peer: {err}");
+                        return;
                     }
-                });
-                let (send_inbound, receive_inbound) = unbounded::<(u64, SocketAddr)>();
-                thread::spawn(move || {
-                    loop {
-                        let mut message = [0u8; 8];
-                        let (len, address) = socket.recv_from(&mut message).unwrap();
-                        info!("Received {len} bytes");
-                        send_inbound
-                            .try_send((u64::from_le_bytes(message), address))
-                            .unwrap();
-                    }
-                });
-                (send_outbound, receive_inbound)
+                }
+
+                app.insert_state(NetworkState::MultiPlayer)
+                    .insert_resource(NetworkSend(send))
+                    .insert_resource(NetworkReceive(receive));
             }
             Err(err) => {
-                error!("Could not bind socket: {err}");
-                todo!("bounded(0) is apparently meaningful so find another solution")
+                warn!("Failed to set up networking: {err}");
             }
         };
-
-        if let Some(socket) = self.peer {
-            send.try_send((0, socket)).unwrap();
-        }
-
-        app.insert_resource(NetworkSend(send));
-        app.insert_resource(NetworkReceive(receive));
     }
 }