better behavior when we try to join twice

CHANGELOG.md

@@ -0,0 +1,36 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+Due to the complexity of Azalea and the fact that almost every Minecraft version
+is breaking anyways, Semantic Versioning is not perfectly followed.
+
+Not all changes will be documented here, but an effort is made to at least
+write down most non-trivial breaking changes.
+
+## [Unreleased]
+
+### Added
+
+- This changelog. To see changes before this update, look at the git commits.
+- azalea and azalea-client now have a `packet-event` feature, which can be disabled for efficiency if you're not using `Event::Packet`.
+- `StartJoinServerEvent` can now be used to join servers exclusively from the ECS without a Tokio runtime.
+- `FormattedText::to_html` and `FormattedText::to_custom_format`.
+- [BREAKING] Add auto-reconnecting, which is enabled by default (and thus could conflict with manually implemented auto-reconnects).
+
+### Changed
+
+- [BREAKING] `Client::goto` is now async and completes when the client reaches its destination. `Client::start_goto` should be used if the old behavior is undesired.
+- [BREAKING] The `BlockState::id` field is now private, use `.id()` instead.
+- [BREAKING] Update to [Bevy 0.16](https://bevyengine.org/news/bevy-0-16/).
+- [BREAKING] Rename `InstanceContainer::insert` to `get_or_insert`.
+- ClientBuilder and SwarmBuilder are now Send.
+
+### Fixed
+
+- Clients now validate incoming packets using the correct `MAXIMUM_UNCOMPRESSED_LENGTH` value.
+- Send the correct UUID to servers in `ClientboundHello` when we're joining in offline-mode.
+- Several protocol fixes, including for ClientboundSetPlayerTeam and a few data components.
+- Update the `InstanceName` component correctly when we receive a respawn or second login packet.
+- Block shapes and some properties were using data from `1.20.3-pre4` due to using an old data generator (Pixlyzer), which has now been replaced with the data generator from [Pumpkin](https://github.com/Pumpkin-MC/Extractor).

azalea-client/src/plugins/join.rs

@@ -34,7 +34,7 @@ impl Plugin for JoinPlugin {
             .add_systems(
                 Update,
                 (
-                    handle_start_join_server_event,
+                    handle_start_join_server_event.before(super::login::poll_auth_task),
                     poll_create_connection_task,
                     handle_connection_failed_events,
                 )
@@ -44,6 +44,9 @@ impl Plugin for JoinPlugin {
 }
 
 /// An event to make a client join the server and be added to our swarm.
+///
+/// This won't do anything if a client with the Account UUID is already
+/// connected to the server.
 #[derive(Event, Debug)]
 pub struct StartJoinServerEvent {
     pub account: Account,
@@ -85,11 +88,30 @@ pub fn handle_start_join_server_event(
     mut commands: Commands,
     mut events: EventReader<StartJoinServerEvent>,
     mut entity_uuid_index: ResMut<EntityUuidIndex>,
+    connection_query: Query<&RawConnection>,
 ) {
     for event in events.read() {
         let uuid = event.account.uuid_or_offline();
         let entity = if let Some(entity) = entity_uuid_index.get(&uuid) {
             debug!("Reusing entity {entity:?} for client");
+
+            // check if it's already connected
+            if let Ok(conn) = connection_query.get(entity) {
+                if conn.is_alive() {
+                    if let Some(start_join_callback_tx) = &event.start_join_callback_tx {
+                        warn!(
+                            "Received StartJoinServerEvent for {entity:?} but it's already connected. Ignoring the event but replying with Ok."
+                        );
+                        let _ = start_join_callback_tx.0.send(Ok(entity));
+                    } else {
+                        warn!(
+                            "Received StartJoinServerEvent for {entity:?} but it's already connected. Ignoring the event."
+                        );
+                    }
+                    return;
+                }
+            }
+
             entity
         } else {
             let entity = commands.spawn_empty().id();
@@ -100,6 +122,7 @@ pub fn handle_start_join_server_event(
         };
 
         let mut entity_mut = commands.entity(entity);
+
         entity_mut.insert((
             // add the Account to the entity now so plugins can access it earlier
             event.account.to_owned(),

azalea-client/src/plugins/login.rs

@@ -33,7 +33,7 @@ fn handle_receive_hello_event(trigger: Trigger<ReceiveHelloEvent>, mut commands:
     commands.entity(player).insert(AuthTask(task));
 }
 
-fn poll_auth_task(
+pub fn poll_auth_task(
     mut commands: Commands,
     mut query: Query<(Entity, &mut AuthTask, &mut RawConnection)>,
 ) {

azalea/examples/testbot/main.rs

@@ -194,7 +194,7 @@ async fn handle(bot: Client, event: azalea::Event, state: State) -> anyhow::Resu
 }
 async fn swarm_handle(_swarm: Swarm, event: SwarmEvent, _state: SwarmState) -> anyhow::Result<()> {
     match &event {
-        SwarmEvent::Disconnect(account, _) => {
+        SwarmEvent::Disconnect(account, _join_opts) => {
             println!("bot got kicked! {}", account.username);
         }
         SwarmEvent::Chat(chat) => {