Remove unnecessary comment

src/pretix/control/middleware.py

@@ -37,7 +37,7 @@ from urllib.parse import quote, urljoin, urlparse
 from django.conf import settings
 from django.contrib.auth import REDIRECT_FIELD_NAME, logout
 from django.contrib.auth.views import redirect_to_login
-from django.http import Http404
+from django.http import Http404, HttpResponse
 from django.shortcuts import get_object_or_404, resolve_url
 from django.template.response import TemplateResponse
 from django.urls import get_script_prefix, resolve, reverse
@@ -98,6 +98,8 @@ class PermissionMiddleware:
         super().__init__()
 
     def _login_redirect(self, request):
+        from django.contrib.auth.views import redirect_to_login
+
         # Taken from django/contrib/auth/decorators.py
         path = request.build_absolute_uri()
         # urlparse chokes on lazy objects in Python 3, force to str
@@ -110,10 +112,21 @@ class PermissionMiddleware:
         if ((not login_scheme or login_scheme == current_scheme) and
                 (not login_netloc or login_netloc == current_netloc)):
             path = request.get_full_path()
-        from django.contrib.auth.views import redirect_to_login
 
-        return redirect_to_login(
-            path, resolved_login_url, REDIRECT_FIELD_NAME)
+        if request.headers.get("X-Requested-With") == "XMLHttpRequest":
+            # It's not useful to return a 302 redirect on a XMLHttpRequest request,  because
+            # the XMLHttpRequest is unable to detect redirects.
+            return HttpResponse(
+                "Authentication required",
+                status=401,
+                headers={
+                    # Appending ?next= is handled by client, because it should be the top-level context url,
+                    # not the URL called in the background
+                    "X-Login-Url": resolved_login_url,
+                }
+            )
+
+        return redirect_to_login(path, resolved_login_url, REDIRECT_FIELD_NAME)
 
     def __call__(self, request):
         url = resolve(request.path_info)

src/pretix/control/templates/pretixcontrol/auth/login.html

@@ -56,5 +56,4 @@
     </form>
     <script type="text/plain" id="good_origin">{{ good_origin }}</script>
     <script type="text/plain" id="bad_origin_report_url">{{ bad_origin_report_url }}</script>
-    <!-- pretix-login-marker -->{# marker required for ajax calls to detect that user session is over #}
 {% endblock %}

src/pretix/plugins/webcheckin/static/pretixplugins/webcheckin/api.ts

@@ -205,8 +205,8 @@ const CSRF_TOKEN = document.querySelector<HTMLInputElement>('input[name=csrfmidd
 function handleAuthError (response: Response): void {
 	if ([401, 403].includes(response.status)) {
 		window.location.href = '/control/login?next=' + encodeURIComponent(
-			window.location.pathname + window.location.search + window.location.hash
-		)
+			window.location.pathname + window.location.search
+		) + window.location.hash
 	}
 }
 

src/pretix/static/pretixbase/js/asynctask.js

@@ -113,6 +113,12 @@ function async_task_check_error(jqXHR, textStatus, errorThrown) {
     "use strict";
     var respdom = $(jqXHR.responseText);
     var c = respdom.filter('.container');
+    if (jqXHR.status === 401 && jqXHR.getResponseHeader("X-Login-Url")) {
+      // Append location.hash outside the next parameter so it is not unexpectedly sent to the server
+      // The browser will keep it in the redirect.
+      window.location = jqXHR.getResponseHeader("X-Login-Url") + "?next=" + encodeURIComponent(location.pathname + location.search) + location.hash;
+      return;
+    }
     if (respdom.filter('form') && (respdom.filter('.has-error') || respdom.filter('.alert-danger'))) {
         // This is a failed form validation, let's just use it
         $("body").data('ajaxing', false);
@@ -167,6 +173,12 @@ function async_task_callback(data, jqXHR, status) {
 function async_task_error(jqXHR, textStatus, errorThrown) {
     "use strict";
     $("body").data('ajaxing', false);
+    if (jqXHR.status === 401 && jqXHR.getResponseHeader("X-Login-Url")) {
+      // Append location.hash outside the next parameter so it is not unexpectedly sent to the server
+      // The browser will keep it in the redirect.
+      window.location = jqXHR.getResponseHeader("X-Login-Url") + "?next=" + encodeURIComponent(location.pathname + location.search) + location.hash;
+      return;
+    }
     waitingDialog.hide();
     if (textStatus === "timeout") {
         alert(gettext("The request took too long. Please try again."));

src/pretix/static/pretixcontrol/js/ui/main.js

@@ -58,13 +58,16 @@ var i18nToString = function (i18nstring) {
 };
 
 $(document).ajaxError(function (event, jqXHR, settings, thrownError) {
-    waitingDialog.hide();
     var c = $(jqXHR.responseText).filter('.container');
-    if (jqXHR.responseText && jqXHR.responseText.indexOf("<!-- pretix-login-marker -->") !== -1) {
-        location.href = '/control/login?next=' + encodeURIComponent(location.pathname + location.search + location.hash)
+    if (jqXHR.status === 401 && jqXHR.getResponseHeader("X-Login-Url")) {
+        // Append location.hash outside the next parameter so it is not unexpectedly sent to the server
+        // The browser will keep it in the redirect.
+        window.location = jqXHR.getResponseHeader("X-Login-Url") + "?next=" + encodeURIComponent(location.pathname + location.search) + location.hash;
     } else if (c.length > 0) {
+        waitingDialog.hide();
         ajaxErrDialog.show(c.first().html());
     } else if (thrownError !== "abort" && thrownError !== "") {
+        waitingDialog.hide();
         console.error(event, jqXHR, settings, thrownError);
         alert(gettext('Unknown error.'));
     }