Adding some basic login response codes so accounts can not log in twice.

src/net/data-parser/client-login-parser.ts

@@ -24,6 +24,23 @@ function longToName(nameLong: BigInt): string {
     return ac.split('').reverse().join('');
 }
 
+/**
+ * Codes for user login attempts that are sent back to the game client
+ * to inform the user of the status of their login attempt.
+ */
+enum LoginResponseCode {
+    SUCCESS = 2,
+    INVALID_CREDENTIALS = 3,
+    ACCOUNT_DISABLED = 4,
+    ALREADY_LOGGED_IN = 5,
+    GAME_UPDATED = 6,
+    WORLD_FULL = 7,
+    LOGIN_SERVER_OFFLINE = 8,
+    LOGIN_LIMIT_EXCEEDED = 9,
+    BAD_SESSION_ID = 10,
+    // @TODO the rest
+}
+
 /**
  * Parses the login packet from the game client.
  */
@@ -83,15 +100,33 @@ export class ClientLoginParser extends DataParser {
             throw new Error(`Server key mismatch - ${this.clientConnection.serverKey} != ${incomingServerKey}`);
         }
 
-        const clientUuid = decrypted.get('INT');
+        const gameClientId = decrypted.get('INT');
         const usernameLong = BigInt(decrypted.get('LONG'));
         const username = longToName(usernameLong);
         const password = decrypted.getString();
 
         logger.info(`Login request: ${username}/${password}`);
 
+        const credentialsResponseCode = this.checkCredentials(username, password);
+        if(credentialsResponseCode === -1) {
+            this.sendLogin([ clientKey1, clientKey2 ], gameClientId, username, password, isLowDetail);
+        } else {
+            logger.warn(`${username} attempted to login but received error code ${ credentialsResponseCode }.`);
+            this.sendLoginResponse(credentialsResponseCode);
+        }
+    }
+
+    /**
+     * Logs a user in and notifies their game client of a successful login.
+     * @param clientKeys The user's client keys (sent by the client).
+     * @param gameClientId The user's game client ID (sent by the client).
+     * @param username The user's username.
+     * @param password The user's password.
+     * @param isLowDetail Whether or not the user selected the "Low Detail" option.
+     */
+    private sendLogin(clientKeys: [ number, number ], gameClientId: number, username: string, password: string, isLowDetail: boolean): void {
         const sessionKey: number[] = [
-            Number(clientKey1), Number(clientKey2), Number(this.clientConnection.serverKey >> BigInt(32)), Number(this.clientConnection.serverKey)
+            Number(clientKeys[0]), Number(clientKeys[1]), Number(this.clientConnection.serverKey >> BigInt(32)), Number(this.clientConnection.serverKey)
         ];
 
         const inCipher = new Isaac(sessionKey);
@@ -102,12 +137,12 @@ export class ClientLoginParser extends DataParser {
 
         const outCipher = new Isaac(sessionKey);
 
-        const player = new Player(this.clientConnection.socket, inCipher, outCipher, clientUuid, username, password, isLowDetail);
+        const player = new Player(this.clientConnection.socket, inCipher, outCipher, gameClientId, username, password, isLowDetail);
 
         world.registerPlayer(player);
 
         const outputBuffer = new ByteBuffer(6);
-        outputBuffer.put(2, 'BYTE'); // login response code
+        outputBuffer.put(LoginResponseCode.SUCCESS, 'BYTE');
         outputBuffer.put(player.rights.valueOf(), 'BYTE');
         outputBuffer.put(0, 'BYTE'); // ???
         outputBuffer.put(player.worldIndex + 1, 'SHORT');
@@ -116,8 +151,44 @@ export class ClientLoginParser extends DataParser {
 
         player.init();
 
-        this.clientConnection.clientKey1 = BigInt(clientKey1);
-        this.clientConnection.clientKey2 = BigInt(clientKey2);
+        this.clientConnection.clientKey1 = BigInt(clientKeys[0]);
+        this.clientConnection.clientKey2 = BigInt(clientKeys[1]);
         this.clientConnection.player = player;
     }
+
+    /**
+     * Validates an incoming user's credentials and returns an error code if a problem occurs.
+     * This also checks if the user is already online.
+     * @param username The incoming user's username input.
+     * @param password The incoming user's password input.
+     */
+    private checkCredentials(username: string, password: string): number {
+        if(!username || !password) {
+            return LoginResponseCode.INVALID_CREDENTIALS;
+        }
+
+        username = username.trim().toLowerCase();
+        password = password.trim();
+
+        if(username === '' || password === '') {
+            return LoginResponseCode.INVALID_CREDENTIALS;
+        }
+
+        if(world.playerOnline(username)) {
+            return LoginResponseCode.ALREADY_LOGGED_IN;
+        }
+
+        return -1;
+    }
+
+    /**
+     * Sends a login response code (by itself) to the game client.
+     * Used for error responses.
+     * @param responseCode The response code to send to the game client.
+     */
+    private sendLoginResponse(responseCode: number): void {
+        const outputBuffer = new ByteBuffer(1);
+        outputBuffer.put(responseCode, 'BYTE');
+        this.clientConnection.socket.write(outputBuffer);
+    }
 }

src/world/actor/player/updating/actor-updating.ts

@@ -35,7 +35,7 @@ export function registerNewActors(packet: Packet, player: Player, trackedActors:
                 continue;
             }
 
-            if(!world.playerExists(nearbyActor)) {
+            if(!world.playerOnline(nearbyActor)) {
                 // Other player is no longer in the game world
                 continue;
             }
@@ -85,7 +85,7 @@ export function updateTrackedActors(packet: Packet, playerPosition: Position, ap
         let exists = true;
 
         if(trackedActor instanceof Player) {
-            if(!world.playerExists(trackedActor as Player)) {
+            if(!world.playerOnline(trackedActor as Player)) {
                 exists = false;
             }
         } else {

src/world/world.ts

@@ -475,13 +475,18 @@ export class World {
         return Promise.resolve();
     }
 
-    public playerExists(player: Player): boolean {
-        const foundPlayer = this.playerList[player.worldIndex];
-        if(!foundPlayer) {
-            return false;
-        }
+    public playerOnline(player: Player | string): boolean {
+        if(typeof player === 'string') {
+            player = player.toLowerCase();
+            return this.playerList.findIndex(p => p !== null && p.username.toLowerCase() === player) !== -1;
+        } else {
+            const foundPlayer = this.playerList[player.worldIndex];
+            if(!foundPlayer) {
+                return false;
+            }
 
-        return foundPlayer.equals(player);
+            return foundPlayer.equals(player);
+        }
     }
 
     public registerPlayer(player: Player): boolean {