add chat and IP limiting

server/config.example.toml

@@ -1,10 +1,15 @@
 [http]
 host = "127.0.0.1"
 port = 3000
+proxied = true
 
 [chat]
 charlimit = 100
 agentsDir = "agents/"
+maxConnectionsPerIP = 2
+
+[chat.ratelimits]
+chat = {seconds = 10, limit = 8}
 
 [tts]
 enabled = true
@@ -62,9 +67,9 @@ filename = "Office_Logo.ACS"
 friendlyName = "Peedy"
 filename = "Peedy.acs"
 
-[[agents]]
-friendlyName = "Question"
-filename = "question_mark.acs"
+#[[agents]]
+#friendlyName = "Question"
+#filename = "question_mark.acs"
 
 [[agents]]
 friendlyName = "Robby"

server/src/client.ts

@@ -3,6 +3,7 @@ import { WebSocket } from "ws";
 import { MSAgentJoinMessage, MSAgentProtocolMessage, MSAgentProtocolMessageType, MSAgentTalkMessage } from '@msagent-chat/protocol';
 import { MSAgentChatRoom } from "./room.js";
 import * as htmlentities from 'html-entities';
+import RateLimiter from "./ratelimiter.js";
 
 // Event types
 
@@ -15,17 +16,25 @@ export interface Client {
 }
 
 export class Client extends EventEmitter {
+    ip: string;
     username: string | null;
     agent: string | null;
 
     room: MSAgentChatRoom;
     socket: WebSocket;
-    constructor(socket: WebSocket, room: MSAgentChatRoom) {
+
+    chatRateLimit: RateLimiter
+
+    constructor(socket: WebSocket, room: MSAgentChatRoom, ip: string) {
         super();
         this.socket = socket;
+        this.ip = ip;
         this.room = room;
         this.username = null;
         this.agent = null;
+        
+        this.chatRateLimit = new RateLimiter(this.room.config.ratelimits.chat);
+
         this.socket.on('message', (msg, isBinary) => {
             if (isBinary) {
                 this.socket.close();
@@ -89,7 +98,7 @@ export class Client extends EventEmitter {
             }
             case MSAgentProtocolMessageType.Talk: {
                 let talkMsg = msg as MSAgentTalkMessage;
-                if (!talkMsg.data || !talkMsg.data.msg) {
+                if (!talkMsg.data || !talkMsg.data.msg || !this.chatRateLimit.request()) {
                     return;
                 }
                 if (talkMsg.data.msg.length > this.room.config.charlimit) return;

server/src/config.ts

@@ -2,6 +2,7 @@ export interface IConfig {
     http: {
         host: string;
         port: number;
+        proxied: boolean;
     }
     chat: ChatConfig;
     tts: TTSConfig;
@@ -19,9 +20,20 @@ export interface TTSConfig {
 export interface ChatConfig {
     charlimit: number;
     agentsDir: string;
+    maxConnectionsPerIP: number;
+    ratelimits: {
+        chat: RateLimitConfig;
+    }
 }
 
 export interface AgentConfig {
     friendlyName: string;
     filename: string;
+}
+
+
+
+export interface RateLimitConfig {
+    seconds: number;
+    limit: number;
 }

server/src/index.ts

@@ -9,6 +9,7 @@ import * as fs from 'fs';
 import { TTSClient } from './tts.js';
 import path from 'path';
 import { fileURLToPath } from 'url';
+import { isIP } from 'net';
 
 let config: IConfig;
 let configPath: string;
@@ -80,7 +81,32 @@ let room = new MSAgentChatRoom(config.chat, config.agents, tts);
 
 app.register(async app => {
     app.get("/api/socket", {websocket: true}, (socket, req) => {
-        let client = new Client(socket, room);
+        // TODO: Do this pre-upgrade and return the appropriate status codes
+        let ip: string;
+        if (config.http.proxied) {
+            if (req.headers["x-forwarded-for"] === undefined) {
+                console.error(`Warning: X-Forwarded-For not set! This is likely a misconfiguration of your reverse proxy.`);
+                socket.close();
+                return;
+            }
+            let xff = req.headers["x-forwarded-for"];
+            if (xff instanceof Array)
+                ip = xff[0];
+            else
+                ip = xff;
+            if (!isIP(ip)) {
+                console.error(`Warning: X-Forwarded-For malformed! This is likely a misconfiguration of your reverse proxy.`);
+                socket.close();
+                return;
+            }
+        } else {
+            ip = req.ip;
+        }
+        let o = room.clients.filter(c => c.ip === ip);
+        if (o.length >= config.chat.maxConnectionsPerIP) {
+            o[0].socket.close();
+        }
+        let client = new Client(socket, room, ip);
         room.addClient(client);
     });
 });

server/src/ratelimiter.ts

@@ -0,0 +1,35 @@
+import { EventEmitter } from 'events';
+import { RateLimitConfig } from './config';
+
+// Class to ratelimit a resource (chatting, logging in, etc)
+export default class RateLimiter extends EventEmitter {
+	private limit: number;
+	private interval: number;
+	private requestCount: number;
+	private limiter?: NodeJS.Timeout;
+	private limiterSet: boolean;
+
+	constructor(config: RateLimitConfig) {
+		super();
+		this.limit = config.limit;
+		this.interval = config.seconds;
+		this.requestCount = 0;
+		this.limiterSet = false;
+	}
+	// Return value is whether or not the action should be continued
+	request(): boolean {
+		this.requestCount++;
+		if (this.requestCount >= this.limit) {
+			this.emit('limit');
+			return false;
+		}
+		if (!this.limiterSet) {
+			this.limiter = setTimeout(() => {
+				this.limiterSet = false;
+				this.requestCount = 0;
+			}, this.interval * 1000);
+			this.limiterSet = true;
+		}
+		return true;
+	}
+}