git init

control-plane/backend/limiter.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"sync"
+	"time"
+)
+
+type loginEntry struct {
+	window time.Time
+	count  int
+	seen   time.Time
+}
+
+type LoginLimiter struct {
+	mu      sync.Mutex
+	entries map[string]loginEntry
+	limit   int
+	window  time.Duration
+	maxKeys int
+}
+
+func NewLoginLimiter(limit int, window time.Duration) *LoginLimiter {
+	return &LoginLimiter{entries: make(map[string]loginEntry), limit: limit, window: window, maxKeys: 10000}
+}
+
+func (limiter *LoginLimiter) Allow(key string, now time.Time) bool {
+	limiter.mu.Lock()
+	defer limiter.mu.Unlock()
+	_, known := limiter.entries[key]
+	if !known && len(limiter.entries) >= limiter.maxKeys {
+		cutoff := now.Add(-2 * limiter.window)
+		for item, entry := range limiter.entries {
+			if entry.seen.Before(cutoff) {
+				delete(limiter.entries, item)
+			}
+		}
+		if len(limiter.entries) >= limiter.maxKeys {
+			return false
+		}
+	}
+	entry := limiter.entries[key]
+	if entry.window.IsZero() || now.Sub(entry.window) >= limiter.window {
+		entry.window, entry.count = now, 0
+	}
+	entry.seen = now
+	if entry.count >= limiter.limit {
+		limiter.entries[key] = entry
+		return false
+	}
+	entry.count++
+	limiter.entries[key] = entry
+	return true
+}