first commit

server/internal/security/rate_limiter.go

@@ -0,0 +1,50 @@
+package security
+
+import (
+	"sync"
+	"time"
+)
+
+type rateEntry struct {
+	count     int
+	windowEnd time.Time
+}
+
+type LoginRateLimiter struct {
+	limit  int
+	window time.Duration
+	mu     sync.Mutex
+	items  map[string]rateEntry
+}
+
+func NewLoginRateLimiter(limit int, window time.Duration) *LoginRateLimiter {
+	return &LoginRateLimiter{
+		limit:  limit,
+		window: window,
+		items:  make(map[string]rateEntry),
+	}
+}
+
+func (r *LoginRateLimiter) Allow(key string) bool {
+	now := time.Now().UTC()
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	entry, ok := r.items[key]
+	if !ok || now.After(entry.windowEnd) {
+		r.items[key] = rateEntry{count: 0, windowEnd: now.Add(r.window)}
+		entry = r.items[key]
+	}
+	if entry.count >= r.limit {
+		return false
+	}
+	entry.count++
+	r.items[key] = entry
+	return true
+}
+
+func (r *LoginRateLimiter) Reset(key string) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	delete(r.items, key)
+}