Add Go VPN admin panel with Docker Compose and Postgres 17.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/auth/auth.go

@@ -0,0 +1,80 @@
+package auth
+
+import (
+	"net/http"
+
+	"github.com/gorilla/sessions"
+	"golang.org/x/crypto/bcrypt"
+)
+
+const SessionName = "vpn_panel_session"
+
+type Manager struct {
+	store *sessions.CookieStore
+}
+
+func New(secret string) *Manager {
+	store := sessions.NewCookieStore([]byte(secret))
+	store.Options = &sessions.Options{
+		Path:     "/",
+		MaxAge:   86400 * 7,
+		HttpOnly: true,
+		SameSite: http.SameSiteLaxMode,
+	}
+	return &Manager{store: store}
+}
+
+func CheckPassword(hash, password string) bool {
+	return bcrypt.CompareHashAndPassword([]byte(hash), []byte(password)) == nil
+}
+
+func (m *Manager) Login(w http.ResponseWriter, r *http.Request, userID, email, name string) error {
+	sess, err := m.store.Get(r, SessionName)
+	if err != nil {
+		sess, _ = m.store.New(r, SessionName)
+	}
+	sess.Values["authenticated"] = true
+	sess.Values["user_id"] = userID
+	sess.Values["email"] = email
+	sess.Values["name"] = name
+	return sess.Save(r, w)
+}
+
+func (m *Manager) Logout(w http.ResponseWriter, r *http.Request) error {
+	sess, _ := m.store.Get(r, SessionName)
+	sess.Values["authenticated"] = false
+	sess.Options.MaxAge = -1
+	return sess.Save(r, w)
+}
+
+func (m *Manager) IsAuthenticated(r *http.Request) bool {
+	sess, err := m.store.Get(r, SessionName)
+	if err != nil {
+		return false
+	}
+	ok, _ := sess.Values["authenticated"].(bool)
+	return ok
+}
+
+func (m *Manager) CurrentName(r *http.Request) string {
+	sess, err := m.store.Get(r, SessionName)
+	if err != nil {
+		return ""
+	}
+	name, _ := sess.Values["name"].(string)
+	if name != "" {
+		return name
+	}
+	email, _ := sess.Values["email"].(string)
+	return email
+}
+
+func (m *Manager) RequireAuth(next http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if !m.IsAuthenticated(r) {
+			http.Redirect(w, r, "/login", http.StatusSeeOther)
+			return
+		}
+		next(w, r)
+	}
+}