From a4a26f04d4c06dd1402318ec218204ac5d8b70cb Mon Sep 17 00:00:00 2001
From: minie4 <minie4@gmx.de>
Date: Tue, 11 Mar 2025 12:32:36 +0100
Subject: [PATCH] fix(backend): fix crash when trying to update player data
 concurrently

---
 backend/api/websocket.go         | 25 +++++++++++++++++++++++++
 backend/db/serializable_types.go |  1 +
 backend/game/game.go             |  1 +
 backend/types/types.go           |  4 ++++
 4 files changed, 31 insertions(+)

diff --git a/backend/api/websocket.go b/backend/api/websocket.go
index 60b739a..abacc4f 100644
--- a/backend/api/websocket.go
+++ b/backend/api/websocket.go
@@ -93,6 +93,9 @@ func onPlayerJoin(client *socket.Socket, room *types.Room, player *types.Player)
 	})
 
 	client.On("UpdatePlayer", func(datas ...any) {
+		player.Mutex.Lock()
+		defer player.Mutex.Unlock()
+
 		updatePlayerRequest := types.C2S_UpdatePlayer{}
 		unpackData(datas, &updatePlayerRequest)
 		if updatePlayerRequest.PlayerId != player.PlayerId && !player.HasPermissionBit(types.PermissionHost) {
@@ -114,6 +117,10 @@ func onPlayerJoin(client *socket.Socket, room *types.Room, player *types.Player)
 		}
 		slog.Debug("Updating player data", "roomId", room.RoomId, "playerId", updatePlayerRequest.PlayerId, "username", targetPlayer.Username, "request", updatePlayerRequest)
 
+		if player != targetPlayer {
+			targetPlayer.Mutex.Lock()
+			defer targetPlayer.Mutex.Unlock()
+		}
 		if updatePlayerRequest.Username != nil {
 			if room.IsUsernameAvailable(*updatePlayerRequest.Username) {
 				targetPlayer.Username = *updatePlayerRequest.Username
@@ -133,6 +140,9 @@ func onPlayerJoin(client *socket.Socket, room *types.Room, player *types.Player)
 	})
 
 	client.On("KickPlayer", func(datas ...any) {
+		player.Mutex.Lock()
+		defer player.Mutex.Unlock()
+
 		kickPlayerRequest := types.C2S_KickPlayer{}
 		unpackData(datas, &kickPlayerRequest)
 		if !player.HasPermissionBit(types.PermissionHost) {
@@ -153,6 +163,9 @@ func onPlayerJoin(client *socket.Socket, room *types.Room, player *types.Player)
 			return
 		}
 
+		if player == targetPlayer {
+			player.Mutex.Unlock()
+		}
 		if room.RemovePlayer(*targetPlayer) {
 			slog.Debug("Player was kicked from room", "playerId", player.PlayerId, "targetPlayerId", kickPlayerRequest.PlayerId, "roomId", room.RoomId)
 			if targetPlayer.Connection.IsConnected && targetPlayer.Connection.Socket != nil {
@@ -163,6 +176,9 @@ func onPlayerJoin(client *socket.Socket, room *types.Room, player *types.Player)
 				})
 			}
 		}
+		if player == targetPlayer {
+			player.Mutex.Lock()
+		}
 		game.OnRoomUpdate(room)
 	})
 
@@ -187,6 +203,9 @@ func onPlayerJoin(client *socket.Socket, room *types.Room, player *types.Player)
 	})
 
 	client.On("DrawCard", func(datas ...any) {
+		player.Mutex.Lock()
+		defer player.Mutex.Unlock()
+
 		if !verifyPlayerIsActivePlayer(room, player) {
 			return
 		}
@@ -199,6 +218,9 @@ func onPlayerJoin(client *socket.Socket, room *types.Room, player *types.Player)
 	})
 
 	client.On("PlayCard", func(datas ...any) {
+		player.Mutex.Lock()
+		defer player.Mutex.Unlock()
+
 		if !verifyPlayerIsActivePlayer(room, player) {
 			return
 		}
@@ -240,6 +262,9 @@ func onPlayerJoin(client *socket.Socket, room *types.Room, player *types.Player)
 	})
 
 	client.On("UpdatePlayedCard", func(datas ...any) {
+		player.Mutex.Lock()
+		defer player.Mutex.Unlock()
+
 		if !verifyPlayerIsActivePlayer(room, player) {
 			return
 		}
diff --git a/backend/db/serializable_types.go b/backend/db/serializable_types.go
index a44cdca..6169b7d 100644
--- a/backend/db/serializable_types.go
+++ b/backend/db/serializable_types.go
@@ -28,6 +28,7 @@ func (serializable *SerializablePlayer) ToPlayer(cardDeckId int) types.Player {
 		Permissions:  serializable.Permissions,
 		Connection:   types.WebsocketConnection{IsConnected: false},
 		Cards:        cards,
+		Mutex:        &sync.Mutex{},
 	}
 	player.ResetInactivity()
 	return player
diff --git a/backend/game/game.go b/backend/game/game.go
index 33967b6..f8582d7 100644
--- a/backend/game/game.go
+++ b/backend/game/game.go
@@ -87,6 +87,7 @@ func JoinRoom(room *types.Room, requestedUsername string) *types.Player {
 		Connection: types.WebsocketConnection{
 			IsConnected: false,
 		},
+		Mutex: &sync.Mutex{},
 	}
 	player.ResetInactivity()
 	room.AppendPlayer(player)
diff --git a/backend/types/types.go b/backend/types/types.go
index 4312ee9..0aaacf7 100644
--- a/backend/types/types.go
+++ b/backend/types/types.go
@@ -35,6 +35,7 @@ type Player struct {
 	Cards             []Card              `json:"-"`
 	Connection        WebsocketConnection `bson:"-" json:"-"`
 	InactivityTimeout int                 `bson:"-" json:"-"`
+	Mutex             *sync.Mutex
 }
 
 func (player *Player) ResetInactivity() {
@@ -93,6 +94,9 @@ func (room *Room) AppendPlayer(player *Player) {
 func (room *Room) RemovePlayer(target Player) bool {
 	room.PlayersMutex.Lock()
 	defer room.PlayersMutex.Unlock()
+	target.Mutex.Lock()
+	defer target.Mutex.Unlock()
+
 	return room.RemovePlayerUnsafe(target)
 }