Fix emoji exploit (#640)

## Description:
This should fix the exploit that allows players to send custom text as
an "emoji". It does this by introducing a emoji ID (index into the emoji
table) instead of sending the raw emoji as a string.

## Please complete the following:

- [ ] I have added screenshots for all UI updates
- [X] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [X] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

## Please put your Discord username so you can be contacted if a bug or
regression is found:
PilkeySEK

src/client/Transport.ts

@@ -88,7 +88,7 @@ export class SendTargetPlayerIntentEvent implements GameEvent {
 export class SendEmojiIntentEvent implements GameEvent {
   constructor(
     public readonly recipient: PlayerView | typeof AllPlayers,
-    public readonly emoji: string,
+    public readonly emoji: number,
   ) {}
 }
 

src/client/graphics/layers/EmojiTable.ts

@@ -4,24 +4,11 @@ import { EventBus } from "../../../core/EventBus";
 import { AllPlayers } from "../../../core/game/Game";
 import { GameView, PlayerView } from "../../../core/game/GameView";
 import { TerraNulliusImpl } from "../../../core/game/TerraNulliusImpl";
+import { emojiTable, flattenedEmojiTable } from "../../../core/Util";
 import { ShowEmojiMenuEvent } from "../../InputHandler";
 import { SendEmojiIntentEvent } from "../../Transport";
 import { TransformHandler } from "../TransformHandler";
 
-const emojiTable: string[][] = [
-  ["😀", "😊", "🥰", "😇", "😎"],
-  ["😞", "🥺", "😭", "😱", "😡"],
-  ["😈", "🤡", "🖕", "🥱", "🤦‍♂️"],
-  ["👋", "👏", "🤌", "💪", "🫡"],
-  ["👍", "👎", "❓", "🐔", "🐀"],
-  ["🤝", "🆘", "🕊️", "🏳️", "⏳"],
-  ["🔥", "💥", "💀", "☢️", "⚠️"],
-  ["↖️", "⬆️", "↗️", "👑", "🥇"],
-  ["⬅️", "🎯", "➡️", "🥈", "🥉"],
-  ["↙️", "⬇️", "↘️", "❤️", "💔"],
-  ["💰", "⚓", "⛵", "🏡", "🛡️"],
-];
-
 @customElement("emoji-table")
 export class EmojiTable extends LitElement {
   public eventBus: EventBus;
@@ -130,7 +117,12 @@ export class EmojiTable extends LitElement {
           targetPlayer == this.game.myPlayer()
             ? AllPlayers
             : (targetPlayer as PlayerView);
-        this.eventBus.emit(new SendEmojiIntentEvent(recipient, emoji));
+        this.eventBus.emit(
+          new SendEmojiIntentEvent(
+            recipient,
+            flattenedEmojiTable.indexOf(emoji),
+          ),
+        );
         this.hideTable();
       });
     });

src/client/graphics/layers/PlayerPanel.ts

@@ -15,6 +15,7 @@ import {
 } from "../../../core/game/Game";
 import { TileRef } from "../../../core/game/GameMap";
 import { GameView, PlayerView } from "../../../core/game/GameView";
+import { flattenedEmojiTable } from "../../../core/Util";
 import { MouseUpEvent } from "../../InputHandler";
 import {
   SendAllianceRequestIntentEvent,
@@ -122,9 +123,16 @@ export class PlayerPanel extends LitElement implements Layer {
     e.stopPropagation();
     this.emojiTable.showTable((emoji: string) => {
       if (myPlayer == other) {
-        this.eventBus.emit(new SendEmojiIntentEvent(AllPlayers, emoji));
+        this.eventBus.emit(
+          new SendEmojiIntentEvent(
+            AllPlayers,
+            flattenedEmojiTable.indexOf(emoji),
+          ),
+        );
       } else {
-        this.eventBus.emit(new SendEmojiIntentEvent(other, emoji));
+        this.eventBus.emit(
+          new SendEmojiIntentEvent(other, flattenedEmojiTable.indexOf(emoji)),
+        );
       }
       this.emojiTable.hideTable();
       this.hide();

src/core/Schemas.ts

@@ -9,6 +9,7 @@ import {
   PlayerType,
   UnitType,
 } from "./game/Game";
+import { flattenedEmojiTable } from "./Util";
 
 export type GameID = string;
 export type ClientID = string;
@@ -133,14 +134,10 @@ const SafeString = z
   )
   .max(1000);
 
-const EmojiSchema = z.string().refine(
-  (val) => {
-    return /\p{Emoji}/u.test(val);
-  },
-  {
-    message: "Must contain at least one emoji character",
-  },
-);
+const EmojiSchema = z
+  .number()
+  .nonnegative()
+  .max(flattenedEmojiTable.length - 1);
 const ID = z
   .string()
   .regex(/^[a-zA-Z0-9]+$/)

src/core/Util.ts

@@ -307,3 +307,19 @@ export function createRandomName(
   }
   return randomName;
 }
+
+export const emojiTable: string[][] = [
+  ["😀", "😊", "🥰", "😇", "😎"],
+  ["😞", "🥺", "😭", "😱", "😡"],
+  ["😈", "🤡", "🖕", "🥱", "🤦‍♂️"],
+  ["👋", "👏", "🤌", "💪", "🫡"],
+  ["👍", "👎", "❓", "🐔", "🐀"],
+  ["🤝", "🆘", "🕊️", "🏳️", "⏳"],
+  ["🔥", "💥", "💀", "☢️", "⚠️"],
+  ["↖️", "⬆️", "↗️", "👑", "🥇"],
+  ["⬅️", "🎯", "➡️", "🥈", "🥉"],
+  ["↙️", "⬇️", "↘️", "❤️", "💔"],
+  ["💰", "⚓", "⛵", "🏡", "🛡️"],
+];
+// 2d to 1d array
+export const flattenedEmojiTable: string[] = [].concat(...emojiTable);

src/core/execution/EmojiExecution.ts

@@ -7,6 +7,7 @@ import {
   PlayerID,
   PlayerType,
 } from "../game/Game";
+import { flattenedEmojiTable } from "../Util";
 
 export class EmojiExecution implements Execution {
   private requestor: Player;
@@ -17,7 +18,7 @@ export class EmojiExecution implements Execution {
   constructor(
     private senderID: PlayerID,
     private recipientID: PlayerID | typeof AllPlayers,
-    private emoji: string,
+    private emoji: number,
   ) {}
 
   init(mg: Game, ticks: number): void {
@@ -38,10 +39,12 @@ export class EmojiExecution implements Execution {
   }
 
   tick(ticks: number): void {
+    const emojiString = flattenedEmojiTable.at(this.emoji);
+
     if (this.requestor.canSendEmoji(this.recipient)) {
-      this.requestor.sendEmoji(this.recipient, this.emoji);
+      this.requestor.sendEmoji(this.recipient, emojiString);
       if (
-        this.emoji == "🖕" &&
+        emojiString == "🖕" &&
         this.recipient != AllPlayers &&
         this.recipient.type() == PlayerType.FakeHuman
       ) {

src/core/execution/FakeHumanExecution.ts

@@ -17,7 +17,7 @@ import {
 import { euclDistFN, manhattanDistFN, TileRef } from "../game/GameMap";
 import { PseudoRandom } from "../PseudoRandom";
 import { GameID } from "../Schemas";
-import { calculateBoundingBox, simpleHash } from "../Util";
+import { calculateBoundingBox, flattenedEmojiTable, simpleHash } from "../Util";
 import { ConstructionExecution } from "./ConstructionExecution";
 import { EmojiExecution } from "./EmojiExecution";
 import { NukeExecution } from "./NukeExecution";
@@ -43,6 +43,7 @@ export class FakeHumanExecution implements Execution {
   private lastEmojiSent = new Map<Player, Tick>();
   private lastNukeSent: [Tick, TileRef][] = [];
   private embargoMalusApplied = new Set<PlayerID>();
+  private heckleEmoji: number[];
 
   constructor(
     gameID: GameID,
@@ -55,6 +56,7 @@ export class FakeHumanExecution implements Execution {
     this.attackTick = this.random.nextInt(0, this.attackRate);
     this.triggerRatio = this.random.nextInt(60, 90) / 100;
     this.reserveRatio = this.random.nextInt(30, 60) / 100;
+    this.heckleEmoji = ["🤡", "😡"].map((e) => flattenedEmojiTable.indexOf(e));
   }
 
   init(mg: Game) {
@@ -267,7 +269,7 @@ export class FakeHumanExecution implements Execution {
       new EmojiExecution(
         this.player.id(),
         enemy.id(),
-        this.random.randElement(["🤡", "😡"]),
+        this.random.randElement(this.heckleEmoji),
       ),
     );
   }

src/core/execution/utils/BotBehavior.ts

@@ -8,6 +8,7 @@ import {
   Tick,
 } from "../../game/Game";
 import { PseudoRandom } from "../../PseudoRandom";
+import { flattenedEmojiTable } from "../../Util";
 import { AttackExecution } from "../AttackExecution";
 import { EmojiExecution } from "../EmojiExecution";
 
@@ -15,13 +16,17 @@ export class BotBehavior {
   private enemy: Player | null = null;
   private enemyUpdated: Tick;
 
+  private assistAcceptEmoji: number;
+
   constructor(
     private random: PseudoRandom,
     private game: Game,
     private player: Player,
     private triggerRatio: number,
     private reserveRatio: number,
-  ) {}
+  ) {
+    this.assistAcceptEmoji = flattenedEmojiTable.indexOf("👍");
+  }
 
   handleAllianceRequests() {
     for (const req of this.player.incomingAllianceRequests()) {
@@ -33,7 +38,7 @@ export class BotBehavior {
     }
   }
 
-  private emoji(player: Player, emoji: string) {
+  private emoji(player: Player, emoji: number) {
     if (player.type() !== PlayerType.Human) return;
     this.game.addExecution(
       new EmojiExecution(this.player.id(), player.id(), emoji),
@@ -78,7 +83,7 @@ export class BotBehavior {
         this.player.updateRelation(ally, -20);
         this.enemy = target;
         this.enemyUpdated = this.game.ticks();
-        this.emoji(ally, "👍");
+        this.emoji(ally, this.assistAcceptEmoji);
         break outer;
       }
     }