golang-utils/utils/http/servlimit/servlimit.go

package servlimit

import (
	"log"
	"net/http"
	"time"

	"github.com/vladimirok5959/golang-utils/utils/http/helpers"
)

var mRequests = &Requests{
	counter:   map[string]int{},
	lastTime:  map[string]int64{},
	cleanTime: time.Now().UTC().Unix(),
}

func ReqPerSecond(handler http.Handler, requests int) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if requests > 0 {
			mRequests.CleanupHourly()
			ip := helpers.ClientIP(r)
			reqs := mRequests.Count(ip)
			ltime := mRequests.Time(ip)

			// Inc counter
			reqs = reqs + 1
			mRequests.SetCount(ip, reqs)

			// Reset counter
			if (time.Now().UTC().Unix() - ltime) >= 1 {
				reqs = 0
				mRequests.SetCount(ip, reqs)
			}

			// Restrict access
			if reqs >= requests {
				w.Header().Set("Retry-After", "1")
				w.WriteHeader(429)
				if _, err := w.Write([]byte("Too Many Requests\n")); err != nil {
					log.Printf("%s\n", err.Error())
				}
				return
			}

			mRequests.SetTime(ip, time.Now().UTC().Unix())
		}

		handler.ServeHTTP(w, r)
	})
}