// The middleware handler
func (l *Limiter) ServeHTTP(w http.ResponseWriter, req *http.Request, next http.HandlerFunc) {
apiKey := req.Header.Get("Api-Key")
// Here, in real life, we would typically create a limiter
// based on information from the given API key
hasher := speedbump.PerMinuteHasher{}
limiter := speedbump.NewLimiter(l.redisConnexion, hasher, 5)
canAccess, err := limiter.Attempt(apiKey)
// Trouble with Redis?
if err != nil {
respondRedisError(w)
return
}
// Over the rate limit?
if !canAccess {
responses.WriteMessage(429, "rate_exceeded", "API rate exceeded. Too many requests.", w)
return
}
requestsLeft, err := limiter.Left(apiKey)
// Trouble with Redis?
if err != nil {
respondRedisError(w)
return
}
// Add the number of remaining request as a header
w.Header().Set("Api-Remaining", strconv.Itoa(int(requestsLeft)))
// Call the next middleware handler
next(w, req)
}
// RateLimitLB is very similar to RateLimit but it takes the X-Forwarded-For
// header in cosideration when trying to figure the IP address of the client.
// This is useful for when running a server behind a load balancer or proxy.
//
// However, this header can be spoofed by the client, so in some cases it could
// provide a way of getting around the rate limiter.
//
// When using this middleware, make sure the load balancer will strip any
// X-Forwarded-For headers set by the client, and that the server will not be
// publicly accessible by the public, just the load balancer.
func RateLimitLB(client *redis.Client, hasher speedbump.RateHasher, max int64) gin.HandlerFunc {
limiter := speedbump.NewLimiter(client, hasher, max)
return func(c *gin.Context) {
// Attempt to perform the request
ip := GetRequesterAddress(c.Request)
ok, err := limiter.Attempt(ip)
if err != nil {
panic(err)
}
if !ok {
nextTime := time.Now().Add(hasher.Duration())
c.JSON(429, gin.H{
"status": "error",
"messages": []string{"Rate limit exceeded. Try again in " + humanize.Time(nextTime)},
})
c.Abort()
}
c.Next()
// After the request
// log.Print(ip + " was limited because it exceeded the max rate")
}
}
func RateLimit(client *redis.Client, hasher speedbump.RateHasher, max int64) negroni.HandlerFunc {
limiter := speedbump.NewLimiter(client, hasher, max)
rnd := render.New()
return func(rw http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
ip, _, _ := net.SplitHostPort(r.RemoteAddr)
ok, err := limiter.Attempt(ip)
if err != nil {
panic(err)
}
if !ok {
nextTime := time.Now().Add(hasher.Duration())
rnd.JSON(rw, 429, map[string]string{"error": "Rate limit exceeded. Try again in " + humanize.Time(nextTime)})
} else {
next(rw, r)
}
}
}
