Add rate limiting

lib/alexa-remote-ext.js

@@ -4,6 +4,7 @@ const known = require('./known-color-values.js');
 const convert = require('./color-convert.js');
 const deltaE = require('./delta-e.js');
 const DEBUG_THIS = tools.DEBUG_THIS;
+const REQUEST_RATE_LIMIT_EXPIRATION_IN_M = 5;
 
 function requireUncached(mod) {
 	delete require.cache[require.resolve(mod)];
@@ -104,6 +105,7 @@ class AlexaRemoteExt extends AlexaRemote {
 
 		this.errorMessagesExt = {};
 		this.smarthomeSimplifiedByEntityIdExt = new Map();
+		this.smarthomeRequestsRateLimit = new Map();
 		this.routineByIdExt = new Map();
 		this.routineByUtteranceExt = new Map();
 		this.musicProvidersExt = [];
@@ -129,6 +131,28 @@ class AlexaRemoteExt extends AlexaRemote {
 		this.logWarn = () => { };
 	}
 
+    _rateLimitRequestHasExpired(date) {
+      const expirationDate = Date.now() - REQUEST_RATE_LIMIT_EXPIRATION_IN_M * 60 * 1000;
+
+      if (expirationDate > date) {
+        return true;
+      } else {
+        return false;
+      }
+    }
+
+	_requestRateLimitCheck(key) {
+	    if (this.smarthomeRequestsRateLimit.has(key)) {
+            if (this._rateLimitRequestHasExpired(this.smarthomeRequestsRateLimit.get(key))) {
+                this.smarthomeRequestsRateLimit.set(key, Date.now());
+            } else {
+                throw new Error('Too many request. Try again in ' + REQUEST_RATE_LIMIT_EXPIRATION_IN_M + ' minutes.');
+            }
+	    } else {
+	        this.smarthomeRequestsRateLimit.set(key, Date.now());
+	    }
+	}
+
 	async initExt(config, proxyActiveCallback = () => { }, logWarn = () => { }, logError = () => { }) {
 		this.logWarn = logWarn;
 		this.logError = logError;
@@ -721,6 +745,8 @@ class AlexaRemoteExt extends AlexaRemote {
 
 	// requests like ['Lamp 1', '1234-DEAD-BEEF-5678' }]
 	async querySmarthomeDeviceStatesExt(requests) {
+	    this._requestRateLimitCheck(JSON.stringify(requests));
+
 		const entities = requests.map(request => this.findSmarthomeEntityExt(request.entity));
 		const nativeRequests = entities.filter(e => e).map(entity => ({
 			entityType: entity.type,
@@ -739,6 +765,8 @@ class AlexaRemoteExt extends AlexaRemote {
 	}
 
 	async querySmarthomeDevicesExt(stateRequests) {
+   	    this._requestRateLimitCheck(JSON.stringify(stateRequests));
+
 		/*
 		'stateRequests': [
 			{
@@ -759,6 +787,7 @@ class AlexaRemoteExt extends AlexaRemote {
 	}
 
 	async executeSmarthomeDeviceActionExt(controlRequests) {
+	    this._requestRateLimitCheck(JSON.stringify(controlRequests));
 		/*
         {
             'controlRequests': [

nodes/alexa-remote-smarthome.html

@@ -1119,7 +1119,7 @@ <h3><strong>References</strong></h3>
 					},
 				});
 			const disclaimerHeader = $('<h3>Please avoid polling!</h3>').insertBefore(inputs);
-			const disclaimerText = $('<p>If your use-case requires it make sure to keep the interval as high as possible.</p>').css({ margin: '0px 0px 24px 0px' }).insertBefore(inputs);
+			const disclaimerText = $('<p>If your use-case requires it, you must keep the interval above 5 minutes, otherwise an error will be thrown.</p>').css({ margin: '0px 0px 24px 0px' }).insertBefore(inputs);
 
 			const select = arSelect(data.option, ['get', 'query', 'action', 'discover', 'forget']);
 			arFormRow(select, 'Select', 'fa fa-sort').insertBefore(inputs);