feat: initpage com sync Go + auth + frontend em web/

internal/middleware/ratelimit.go

@@ -0,0 +1,66 @@
+package middleware
+
+import (
+	"net/http"
+	"sync"
+	"time"
+
+	"golang.org/x/time/rate"
+)
+
+type IPRateLimiter struct {
+	mu       sync.RWMutex
+	limiters map[string]*rate.Limiter
+	r        rate.Limit
+	b        int
+}
+
+func NewIPRateLimiter(r rate.Limit, b int) *IPRateLimiter {
+	return &IPRateLimiter{
+		limiters: make(map[string]*rate.Limiter),
+		r:        r,
+		b:        b,
+	}
+}
+
+func (i *IPRateLimiter) GetLimiter(ip string) *rate.Limiter {
+	i.mu.Lock()
+	defer i.mu.Unlock()
+	if lim, ok := i.limiters[ip]; ok {
+		return lim
+	}
+	lim := rate.NewLimiter(i.r, i.b)
+	i.limiters[ip] = lim
+	return lim
+}
+
+func (i *IPRateLimiter) Cleanup() {
+	ticker := time.NewTicker(time.Minute)
+	go func() {
+		for range ticker.C {
+			i.mu.Lock()
+			for k := range i.limiters {
+				delete(i.limiters, k)
+			}
+			i.mu.Unlock()
+		}
+	}()
+}
+
+func RateLimit(l *IPRateLimiter) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			ip := r.RemoteAddr
+			if xf := r.Header.Get("X-Forwarded-For"); xf != "" {
+				// simples, suficiente pra começar
+				ip = xf
+			}
+			if !l.GetLimiter(ip).Allow() {
+				w.WriteHeader(http.StatusTooManyRequests)
+				w.Write([]byte(`{"error":"muitas tentativas, tente novamente mais tarde"}`))
+				return
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}