feat: add fail2ban service

internal/services/fail2ban/fail.go

@@ -0,0 +1,71 @@
+package fail2ban
+
+import (
+	"sync"
+	"time"
+)
+
+type Client struct {
+	FailedAttempts int
+	BlockedUntil   time.Time
+}
+
+type Fail2Ban struct {
+	mu      sync.Mutex
+	clients map[string]*Client
+}
+
+func NewFail2Ban() *Fail2Ban {
+	return &Fail2Ban{
+		clients: make(map[string]*Client),
+		mu:      sync.Mutex{},
+	}
+}
+
+func (f *Fail2Ban) FailedAttempt(ip string) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
+	client, ok := f.clients[ip]
+	if !ok {
+		client = &Client{}
+		f.clients[ip] = client
+	}
+
+	client.FailedAttempts++
+	if client.FailedAttempts >= 3 {
+		client.BlockedUntil = time.Now().Add(10 * time.Minute)
+		client.FailedAttempts = 0
+
+		// Automatically unblock the client after 1 hour
+		time.AfterFunc(1*time.Hour, func() {
+			f.unblockClient(ip)
+		})
+	}
+}
+
+func (f *Fail2Ban) unblockClient(ip string) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
+	client, ok := f.clients[ip]
+	if ok {
+		client.BlockedUntil = time.Time{}
+	}
+}
+
+func (f *Fail2Ban) CanChangePassword(ip string) bool {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
+	client, ok := f.clients[ip]
+	if !ok {
+		return true
+	}
+
+	if time.Now().Before(client.BlockedUntil) {
+		return false
+	}
+
+	return true
+}