chore: adding rate limit config (#12)

waku/nwaku.go

@@ -360,6 +360,48 @@ type WakuConfig struct {
 	PeerExchange                bool             `json:"peerExchange,omitempty"`
 	PeerExchangeNode            string           `json:"peerExchangeNode,omitempty"`
 	TcpPort                     int              `json:"tcpPort,omitempty"`
+	RateLimits                  RateLimitsConfig `json:"rateLimits,omitempty"`
+}
+
+type RateLimitsConfig struct {
+	Filter       *RateLimit `json:"-"`
+	Lightpush    *RateLimit `json:"-"`
+	PeerExchange *RateLimit `json:"-"`
+}
+
+func (rlc RateLimitsConfig) MarshalJSON() ([]byte, error) {
+	output := []string{}
+	if rlc.Filter != nil {
+		output = append(output, fmt.Sprintf("filter:%s", rlc.Filter.String()))
+	}
+	if rlc.Lightpush != nil {
+		output = append(output, fmt.Sprintf("lightpush:%s", rlc.Lightpush.String()))
+	}
+	if rlc.PeerExchange != nil {
+		output = append(output, fmt.Sprintf("px:%s", rlc.PeerExchange.String()))
+	}
+	return json.Marshal(output)
+}
+
+type RateLimitTimeUnit string
+
+const Hour RateLimitTimeUnit = "h"
+const Minute RateLimitTimeUnit = "m"
+const Second RateLimitTimeUnit = "s"
+const Millisecond RateLimitTimeUnit = "ms"
+
+type RateLimit struct {
+	Volume   int               // Number of allowed messages per period
+	Period   int               // Length of each rate-limit period (in TimeUnit)
+	TimeUnit RateLimitTimeUnit // Time unit of the period
+}
+
+func (rl RateLimit) String() string {
+	return fmt.Sprintf("%d/%d%s", rl.Volume, rl.Period, rl.TimeUnit)
+}
+
+func (rl RateLimit) MarshalJSON() ([]byte, error) {
+	return json.Marshal(rl.String())
 }
 
 // Waku represents a dark communication interface through the Ethereum