Consistently set default background PDFs on server, not client (#2840)

Co-authored-by: Martin Gross <gross@rami.io>

src/pretix/multidomain/utils.py

@@ -0,0 +1,47 @@
+#
+# This file is part of pretix (Community Edition).
+#
+# Copyright (C) 2014-2020 Raphael Michel and contributors
+# Copyright (C) 2020-2021 rami.io GmbH and contributors
+#
+# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
+# Public License as published by the Free Software Foundation in version 3 of the License.
+#
+# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
+# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
+# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
+# this file, see <https://pretix.eu/about/en/license>.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
+# <https://www.gnu.org/licenses/>.
+#
+from urllib.parse import urljoin, urlsplit
+
+from django.conf import settings
+from django.templatetags.static import static
+
+from pretix.base.models import Event
+from pretix.multidomain.urlreverse import (
+    get_event_domain, get_organizer_domain,
+)
+
+
+def static_absolute(object, path):
+    sp = static(path)
+    if sp.startswith("/"):
+        if isinstance(object, Event):
+            domain = get_event_domain(object, fallback=True)
+        else:
+            domain = get_organizer_domain(object)
+        if domain:
+            siteurlsplit = urlsplit(settings.SITE_URL)
+            if siteurlsplit.port and siteurlsplit.port not in (80, 443):
+                domain = '%s:%d' % (domain, siteurlsplit.port)
+            sp = urljoin('%s://%s' % (siteurlsplit.scheme, domain), sp)
+        else:
+            sp = urljoin(settings.SITE_URL, sp)
+    return sp