// Write msg as error and report e to log
func Error(w http.ResponseWriter, e error, msg string) {
if e != nil {
log.Println("%v", e)
}
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(500)
if e := FlushJson(w, Reply(false, msg)); e != nil {
panic(e)
}
}
// Limit the amount of requests one IP can do per second.
//
// fillrate = Amount of requests allowed in one second
// capacity = Amount of 'extra'(burst) requests a-top fillrate allowed
// delay = Duration before changing http status 429 to 503
//
// If the fillrate+capacity are overloaded a HTTP 429 is returned
// If the callee keeps firing requests the 429 is changed into a 503
// if delay is passed.
func Use(fillrate float64, capacity float64) middleware.HandlerFunc {
cache = lru.New(CacheSize)
// Some sanity checks on fillrate and capacity
if fillrate > capacity {
panic("ratelimit: fillrate must be equal to or lower than capacity")
}
if fillrate < 1.0 {
panic("ratelimit: fillrate must be equal to or higher than 1")
}
// Everything is OK
return func(w http.ResponseWriter, r *http.Request) bool {
httpCode := check(r.RemoteAddr, fillrate, capacity)
switch httpCode {
case StatusRateLimit:
// Ratelimit request
log.Println("ratelimit: Dropped HTTP %s (IP=%s)", r.URL.String(), r.RemoteAddr)
w.Header().Set("Retry-After", strconv.Itoa(Delay))
w.WriteHeader(StatusRateLimit)
if e := httpd.FlushJson(w, httpd.Reply(false, StatusRateLimitText)); e != nil {
httpd.Error(w, e, "Flush failed")
}
return false
case http.StatusServiceUnavailable:
// Abusive client, responding less friendly
log.Println("ratelimit: Banned abusive HTTP %s (IP=%s)", r.URL.String(), r.RemoteAddr)
w.Header().Set("Retry-After", strconv.Itoa(Delay))
w.WriteHeader(http.StatusServiceUnavailable)
if e := httpd.FlushJson(w, httpd.Reply(false, http.StatusText(http.StatusServiceUnavailable))); e != nil {
httpd.Error(w, e, "Flush failed")
}
return false
default:
return true
}
}
}