refactor(session): store user ID in session instead of full struct

Replaces storing the full User object in the session cookie with just
the user ID. GetLoginUser now re-fetches the user from the database on
every request so credential/permission changes take effect immediately
without requiring a re-login. Includes a backward-compatible migration
path for existing sessions that still carry the old struct payload.

web/session/session.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/mhsanaei/3x-ui/v3/database"
 	"github.com/mhsanaei/3x-ui/v3/database/model"
 	"github.com/mhsanaei/3x-ui/v3/logger"
 
@@ -27,7 +28,7 @@ func SetLoginUser(c *gin.Context, user *model.User) error {
 		return nil
 	}
 	s := sessions.Default(c)
-	s.Set(loginUserKey, *user)
+	s.Set(loginUserKey, user.Id)
 	return s.Save()
 }
 
@@ -49,7 +50,7 @@ func GetLoginUser(c *gin.Context) *model.User {
 	if obj == nil {
 		return nil
 	}
-	user, ok := obj.(model.User)
+	userID, ok := sessionUserID(obj)
 	if !ok {
 		s.Delete(loginUserKey)
 		if err := s.Save(); err != nil {
@@ -57,13 +58,77 @@ func GetLoginUser(c *gin.Context) *model.User {
 		}
 		return nil
 	}
-	return &user
+	if legacyUserID, ok := legacySessionUserID(obj); ok {
+		s.Set(loginUserKey, legacyUserID)
+		if err := s.Save(); err != nil {
+			logger.Warning("session: failed to migrate legacy user payload:", err)
+		}
+	}
+	user, err := getUserByID(userID)
+	if err != nil {
+		logger.Warning("session: failed to load user:", err)
+		s.Delete(loginUserKey)
+		if saveErr := s.Save(); saveErr != nil {
+			logger.Warning("session: failed to drop missing user:", saveErr)
+		}
+		return nil
+	}
+	return user
 }
 
 func IsLogin(c *gin.Context) bool {
 	return GetLoginUser(c) != nil
 }
 
+func sessionUserID(obj any) (int, bool) {
+	switch v := obj.(type) {
+	case int:
+		return v, v > 0
+	case int64:
+		return int(v), v > 0
+	case int32:
+		return int(v), v > 0
+	case float64:
+		id := int(v)
+		return id, v == float64(id) && id > 0
+	case model.User:
+		return v.Id, v.Id > 0
+	case *model.User:
+		if v == nil {
+			return 0, false
+		}
+		return v.Id, v.Id > 0
+	default:
+		return 0, false
+	}
+}
+
+func legacySessionUserID(obj any) (int, bool) {
+	switch v := obj.(type) {
+	case model.User:
+		return v.Id, v.Id > 0
+	case *model.User:
+		if v == nil {
+			return 0, false
+		}
+		return v.Id, v.Id > 0
+	default:
+		return 0, false
+	}
+}
+
+func getUserByID(id int) (*model.User, error) {
+	db := database.GetDB()
+	if db == nil {
+		return nil, http.ErrServerClosed
+	}
+	user := &model.User{}
+	if err := db.Model(model.User{}).Where("id = ?", id).First(user).Error; err != nil {
+		return nil, err
+	}
+	return user, nil
+}
+
 func ClearSession(c *gin.Context) error {
 	s := sessions.Default(c)
 	s.Clear()

web/session/session_test.go

@@ -0,0 +1,47 @@
+package session
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/mhsanaei/3x-ui/v3/database/model"
+
+	"github.com/gin-contrib/sessions"
+	"github.com/gin-contrib/sessions/cookie"
+	"github.com/gin-gonic/gin"
+)
+
+func TestSetLoginUserStoresOnlyUserID(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	router := gin.New()
+	router.Use(sessions.Sessions(sessionCookieName, cookie.NewStore([]byte("01234567890123456789012345678901"))))
+	router.GET("/", func(c *gin.Context) {
+		if err := SetLoginUser(c, &model.User{Id: 7, Username: "admin", Password: "hash"}); err != nil {
+			t.Fatal(err)
+		}
+		got := sessions.Default(c).Get(loginUserKey)
+		if got != 7 {
+			t.Fatalf("stored session payload = %#v, want user id only", got)
+		}
+		c.Status(http.StatusNoContent)
+	})
+
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	router.ServeHTTP(rec, req)
+	if rec.Code != http.StatusNoContent {
+		t.Fatalf("status = %d, want %d", rec.Code, http.StatusNoContent)
+	}
+}
+
+func TestSessionUserIDSupportsLegacyUserPayload(t *testing.T) {
+	id, ok := sessionUserID(model.User{Id: 11, Username: "admin", Password: "hash"})
+	if !ok || id != 11 {
+		t.Fatalf("legacy session payload resolved to (%d, %v), want (11, true)", id, ok)
+	}
+	id, ok = sessionUserID(&model.User{Id: 12, Username: "admin", Password: "hash"})
+	if !ok || id != 12 {
+		t.Fatalf("legacy pointer session payload resolved to (%d, %v), want (12, true)", id, ok)
+	}
+}