Expand upon flood detection and chat rate limiting. Closes #1349

core/chat/chatclient.go

@@ -25,6 +25,8 @@ type ChatClient struct {
 	// Buffered channel of outbound messages.
 	send         chan []byte
 	rateLimiter  *rate.Limiter
+	timeoutTimer *time.Timer
+	inTimeout    bool
 	Geo          *geoip.GeoDetails `json:"geo"`
 	MessageCount int               `json:"messageCount"`
 	UserAgent    string            `json:"userAgent"`
@@ -72,7 +74,9 @@ func (c *ChatClient) sendConnectedClientInfo() {
 }
 
 func (c *ChatClient) readPump() {
-	c.rateLimiter = rate.NewLimiter(0.6, 5)
+	// Allow 3 messages every two seconds.
+	limit := rate.Every(2 * time.Second / 3)
+	c.rateLimiter = rate.NewLimiter(limit, 1)
 
 	defer func() {
 		c.close()
@@ -100,8 +104,16 @@ func (c *ChatClient) readPump() {
 			continue
 		}
 
+		// Check if this client is temporarily blocked from sending messages.
+		if c.inTimeout {
+			continue
+		}
+
 		// Guard against floods.
 		if !c.passesRateLimit() {
+			log.Warnln("Client", c.id, c.User.DisplayName, "has exceeded the messaging rate limiting thresholds and messages are being rejected temporarily.")
+			c.startChatRejectionTimeout()
+
 			continue
 		}
 
@@ -171,12 +183,24 @@ func (c *ChatClient) close() {
 }
 
 func (c *ChatClient) passesRateLimit() bool {
-	if !c.rateLimiter.Allow() {
-		log.Debugln("Client", c.id, c.User.DisplayName, "has exceeded the messaging rate limiting thresholds.")
-		return false
+	return c.rateLimiter.Allow() && !c.inTimeout
+}
+
+func (c *ChatClient) startChatRejectionTimeout() {
+	if c.timeoutTimer != nil {
+		return
 	}
 
-	return true
+	c.inTimeout = true
+	c.timeoutTimer = time.NewTimer(10 * time.Second)
+	go func(c *ChatClient) {
+		for range c.timeoutTimer.C {
+			c.inTimeout = false
+			c.timeoutTimer = nil
+		}
+	}(c)
+
+	c.sendAction("You are temporarily blocked from sending chat messages due to perceived flooding.")
 }
 
 func (c *ChatClient) sendPayload(payload events.EventPayload) {