Allow clients to create new rooms to play

board-network/src/protocol.rs

@@ -11,5 +11,9 @@ pub enum ClientMessage {
 pub enum ServerMessage {
     JoinedRoom {
         room_name: String,
+        players: Vec<(String, u32, bool)>,
     },
+    PlayerConnected(String),
+    PlayerReconnected(usize),
+    PlayerDisconnected(usize),
 }

board-server/Cargo.toml

@@ -13,3 +13,5 @@ smol = "1.3.0"
 async-tungstenite = "0.20.0"
 tungstenite = "0.18.0"
 anyhow = "1.0.69"
+rand = "0.8.5"
+serde_json = "1.0.93"

board-server/README.md

@@ -0,0 +1,50 @@
+# WebSocket server implementation
+
+This crate provides a WebSocket server for the Scrabble with numbers game.
+
+## Build
+
+This project uses [Cargo](https://crates.io/), so ensure you have it installed.
+
+```bash
+cargo build --release
+```
+
+## Usage
+
+The server listens on port `8080` by default. You can change this by specifying a program argument:
+
+```bash
+# Run a debug build on port 1234
+cargo run -- '0.0.0.0:1234'
+# Run an already built binary on the default port
+./board-server
+```
+
+## Protocol
+
+The server only understands certain predefined messages.
+All messages are sent as JSON strings are can only be sent by either the client or the server.
+
+You can see the exact layout of the messages in the [protocol file](../board-network/src/protocol.rs).
+
+Messages sent and received shouldn't contain any unnecessary indentation.
+
+## Sample client
+
+```js
+// Create WebSocket connection.
+const socket = new WebSocket('ws://localhost:8080');
+
+// Connection opened
+socket.addEventListener('open', (event) => {
+    // Create a new room, and join it it immediately with the player name "player_name"
+    // The server will respond with a RoomCreated message which contains the room name
+    socket.send(JSON.stringify({ CreateRoom: 'player_name' }));
+});
+
+// Listen for messages
+socket.addEventListener('message', (event) => {
+    console.log('Message from server', JSON.parse(event.data));
+});
+```

board-server/src/main.rs

@@ -1,17 +1,103 @@
+mod player;
+mod room;
+
+use crate::room::{generate_room_name, Room, RoomHandle};
 use anyhow::Result;
-use futures::StreamExt;
+use async_tungstenite::WebSocketStream;
+use board_network::protocol::ClientMessage;
+use futures::channel::mpsc::{unbounded, UnboundedSender};
+use futures::future::join;
+use futures::{future, SinkExt, StreamExt};
 use smol::Async;
+use std::collections::HashMap;
 use std::net::{SocketAddr, TcpListener, TcpStream};
+use std::sync::{Arc, Mutex};
 use std::{env, io};
 use tungstenite::Message as WebsocketMessage;
 
-async fn handle_connection(raw_stream: Async<TcpStream>, addr: SocketAddr) -> Result<()> {
+type Rooms = Arc<Mutex<HashMap<String, RoomHandle>>>;
+
+async fn run_player(
+    player_name: String,
+    addr: SocketAddr,
+    handle: RoomHandle,
+    ws_stream: WebSocketStream<Async<TcpStream>>,
+) {
+    let (incoming, outgoing) = ws_stream.split();
+    let (tx, rx) = unbounded();
+
+    {
+        let room = &mut handle.room.lock().unwrap();
+        if let Err(e) = room.add_player(addr, player_name.clone(), tx) {
+            eprintln!("[{}] Failed to add player: {:?}", room.name, e);
+            return;
+        }
+    }
+
+    let write = handle.write.clone();
+    let ra = rx
+        .map(|c| {
+            serde_json::to_string(&c).unwrap_or_else(|_| panic!("Could not serialize {:?}", c))
+        })
+        .map(WebsocketMessage::Text)
+        .map(Ok)
+        .forward(incoming);
+    let rb = outgoing
+        .map(|m| match m {
+            Ok(WebsocketMessage::Text(t)) => serde_json::from_str::<ClientMessage>(&t).ok(),
+            _ => None,
+        })
+        .take_while(|m| future::ready(m.is_some()))
+        .map(|m| m.unwrap())
+        .chain(futures::stream::once(async { ClientMessage::Disconnected }))
+        .map(move |m| Ok((addr, m)))
+        .forward(write);
+
+    let (ra, rb) = join(ra, rb).await;
+    if let Err(e) = ra {
+        eprintln!("[{addr}] Got error {e} from player {player_name}'s rx queue");
+    }
+    if let Err(e) = rb {
+        eprintln!("[{addr}] Got error {e} from player {player_name}'s tx queue");
+    }
+    println!("[{addr}] Finished session with {player_name}");
+}
+
+async fn handle_connection(
+    rooms: Rooms,
+    raw_stream: Async<TcpStream>,
+    addr: SocketAddr,
+    mut close_room: UnboundedSender<String>,
+) -> Result<()> {
     println!("[{addr}] Incoming TCP connection");
     let mut ws_stream = async_tungstenite::accept_async(raw_stream).await?;
     println!("[{addr}] WebSocket connection established");
 
-    while let Some(Ok(WebsocketMessage::Text(text))) = ws_stream.next().await {
-        println!("[{addr}] Received message: {text}");
+    if let Some(Ok(WebsocketMessage::Text(text))) = ws_stream.next().await {
+        let msg = serde_json::from_str::<ClientMessage>(&text)?;
+        match msg {
+            ClientMessage::CreateRoom(player_name) => {
+                let (write, read) = unbounded();
+                let room = Arc::new(Mutex::new(Room::default()));
+                let handle = RoomHandle { write, room };
+                let room_name = generate_room_name(&mut rooms.lock().unwrap(), handle.clone());
+                println!("[{addr}] Creating room '{room_name}' for player '{player_name}'");
+
+                let mut h = handle.clone();
+                join(
+                    h.run_room(read),
+                    run_player(player_name, addr, handle, ws_stream),
+                )
+                .await;
+
+                if let Err(e) = close_room.send(room_name.clone()).await {
+                    eprintln!("[{room_name}] Failed to close room: {e}");
+                }
+
+                return Ok(());
+            }
+            msg => eprintln!("[{addr}] Received illegal message {:?}", msg),
+        }
     }
 
     println!("[{addr}] Dropping connection");
@@ -25,13 +111,30 @@ fn main() -> Result<(), io::Error> {
         .parse::<SocketAddr>()
         .expect("Invalid address");
 
+    let rooms = Rooms::new(Mutex::new(HashMap::new()));
+
+    let close_room = {
+        let (tx, mut rx) = unbounded();
+        let rooms = rooms.clone();
+        smol::spawn(async move {
+            while let Some(room_name) = rx.next().await {
+                println!("Closing room {room_name}");
+                rooms.lock().unwrap().remove(&room_name);
+            }
+        })
+        .detach();
+        tx
+    };
+
     smol::block_on(async {
         println!("Listening on: {addr}");
         let listener = Async::<TcpListener>::bind(addr).expect("Could not create listener");
 
         while let Ok((stream, addr)) = listener.accept().await {
+            let close_room = close_room.clone();
+            let rooms = rooms.clone();
             smol::spawn(async move {
-                if let Err(e) = handle_connection(stream, addr).await {
+                if let Err(e) = handle_connection(rooms, stream, addr, close_room).await {
                     eprintln!("Failed to handle connection from {addr}: {e}");
                 }
             })

board-server/src/player.rs

@@ -0,0 +1,9 @@
+use board_network::protocol::ServerMessage;
+use futures::channel::mpsc::UnboundedSender;
+
+#[derive(Debug)]
+pub struct Player {
+    pub name: String,
+    pub score: u32,
+    pub ws: Option<UnboundedSender<ServerMessage>>,
+}

board-server/src/room.rs

@@ -0,0 +1,129 @@
+use crate::player::Player;
+use board_network::protocol::{ClientMessage, ServerMessage};
+use futures::channel::mpsc::{UnboundedReceiver, UnboundedSender};
+use futures::StreamExt;
+use rand::distributions::{Alphanumeric, DistString};
+use std::collections::hash_map::Entry;
+use std::collections::HashMap;
+use std::net::SocketAddr;
+use std::sync::{Arc, Mutex};
+
+type TaggedClientMessage = (SocketAddr, ClientMessage);
+
+#[derive(Debug, Default)]
+pub struct Room {
+    pub name: String,
+    pub connections: HashMap<SocketAddr, usize>,
+    pub players: Vec<Player>,
+}
+
+impl Room {
+    pub fn add_player(
+        &mut self,
+        addr: SocketAddr,
+        player_name: String,
+        tx: UnboundedSender<ServerMessage>,
+    ) -> anyhow::Result<()> {
+        // If the player name matches an existing player, but with a dropped connection,
+        // then replace this player.
+        let mut player_index = None;
+        for (i, p) in self.players.iter().enumerate() {
+            if p.name == player_name && p.ws.is_none() {
+                player_index = Some(i);
+                break;
+            }
+        }
+
+        if let Some(i) = player_index {
+            // Reclaim the player's spot
+            self.broadcast(ServerMessage::PlayerReconnected(i));
+            self.players[i].ws = Some(tx.clone());
+        } else {
+            self.broadcast(ServerMessage::PlayerConnected(player_name.clone()));
+            player_index = Some(self.players.len());
+
+            self.players.push(Player {
+                name: player_name,
+                score: 0,
+                ws: Some(tx.clone()),
+            });
+        }
+
+        let player_index = player_index.expect("A player index should have been attributed");
+        self.connections.insert(addr, player_index);
+
+        // Send the player the current state of the room
+        tx.unbounded_send(ServerMessage::JoinedRoom {
+            room_name: self.name.clone(),
+            players: self
+                .players
+                .iter()
+                .map(|p| (p.name.clone(), p.score, p.ws.is_some()))
+                .collect(),
+        })?;
+
+        Ok(())
+    }
+
+    pub fn on_message(&mut self, addr: SocketAddr, msg: ClientMessage) -> bool {
+        match msg {
+            ClientMessage::Disconnected => self.on_client_disconnected(addr),
+            ClientMessage::CreateRoom(_) | ClientMessage::JoinRoom(_, _) => {
+                eprintln!("[{}] Illegal client message {:?}", self.name, msg);
+            }
+        }
+        !self.connections.is_empty()
+    }
+
+    fn on_client_disconnected(&mut self, addr: SocketAddr) {
+        if let Some(p) = self.connections.remove(&addr) {
+            self.players[p].ws = None;
+            self.broadcast(ServerMessage::PlayerDisconnected(p));
+        }
+    }
+
+    fn broadcast(&self, s: ServerMessage) {
+        for c in self.connections.values() {
+            if let Some(ws) = &self.players[*c].ws {
+                if let Err(e) = ws.unbounded_send(s.clone()) {
+                    eprintln!(
+                        "[{}] Failed to send broadcast to {}: {}",
+                        self.name, self.players[*c].name, e
+                    );
+                }
+            }
+        }
+    }
+}
+
+type RoomPtr = Arc<Mutex<Room>>;
+
+#[derive(Clone)]
+pub struct RoomHandle {
+    pub write: UnboundedSender<TaggedClientMessage>,
+    pub room: RoomPtr,
+}
+
+impl RoomHandle {
+    pub async fn run_room(&mut self, mut read: UnboundedReceiver<TaggedClientMessage>) {
+        while let Some((addr, msg)) = read.next().await {
+            if !self.room.lock().unwrap().on_message(addr, msg) {
+                break;
+            }
+        }
+    }
+}
+
+pub type Rooms = HashMap<String, RoomHandle>;
+
+pub fn generate_room_name(rooms: &mut Rooms, room: RoomHandle) -> String {
+    let mut rng = rand::thread_rng();
+    loop {
+        let name = Alphanumeric.sample_string(&mut rng, 5);
+        if let Entry::Vacant(v) = rooms.entry(name.clone()) {
+            room.room.lock().unwrap().name = name.clone();
+            v.insert(room);
+            return name;
+        }
+    }
+}