From 0fa52645c2605be8afd3e63f92ccfb068e106131 Mon Sep 17 00:00:00 2001
From: jedi <git@m.j3d1.de>
Date: Sat, 18 Jan 2025 22:15:04 +0100
Subject: [PATCH] handle plain base64 as transfer-encoding in incoming mails

---
 core/mail/protocol.py            |  8 ++++++--
 core/mail/tests/v2/test_mails.py | 31 ++++++++++++++++++++++++++++++-
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/core/mail/protocol.py b/core/mail/protocol.py
index 7fe6942..00872f0 100644
--- a/core/mail/protocol.py
+++ b/core/mail/protocol.py
@@ -128,10 +128,14 @@ def decode_email_segment(segment, charset, transfer_encoding):
         decode_as = 'cp1251'
     elif charset == 'iso-8859-1':
         decode_as = 'latin1'
-    segment = unescape_and_decode_quoted_printable(segment)
-    segment = unescape_and_decode_base64(segment)
     if transfer_encoding == 'quoted-printable':
         segment = unescape_simplified_quoted_printable(segment, decode_as)
+    elif transfer_encoding == 'base64':
+        import base64
+        segment = base64.b64decode(segment).decode('utf-8')
+    else:
+        segment = unescape_and_decode_quoted_printable(segment)
+        segment = unescape_and_decode_base64(segment)
     return segment
 
 
diff --git a/core/mail/tests/v2/test_mails.py b/core/mail/tests/v2/test_mails.py
index 455faf1..d2f33fe 100644
--- a/core/mail/tests/v2/test_mails.py
+++ b/core/mail/tests/v2/test_mails.py
@@ -165,7 +165,7 @@ class LMTPHandlerTestCase(TestCase):  # TODO replace with less hacky test
         self.assertEqual('Text mit Quoted-Printable-Kodierung: äöüß', Email.objects.all()[0].body)
         self.assertTrue(Email.objects.all()[0].raw_file.path)
 
-    def test_handle_base64(self):
+    def test_handle_base64_inline(self):
         from aiosmtpd.smtp import Envelope
         from asgiref.sync import async_to_sync
         import aiosmtplib
@@ -186,6 +186,35 @@ class LMTPHandlerTestCase(TestCase):  # TODO replace with less hacky test
         self.assertEqual('Text mit Base64-Kodierung: äöüß', Email.objects.all()[0].body)
         self.assertTrue(Email.objects.all()[0].raw_file.path)
 
+    def test_handle_base64_transfer_encoding(self):
+        from aiosmtpd.smtp import Envelope
+        from asgiref.sync import async_to_sync
+        import aiosmtplib
+        aiosmtplib.send = make_mocked_coro()
+        handler = LMTPHandler()
+        server = mock.Mock()
+        session = mock.Mock()
+        envelope = Envelope()
+        envelope.mail_from = 'test1@test'
+        envelope.rcpt_tos = ['test2@test']
+        envelope.content = b'''Subject: test
+From: test3@test
+To: test4@test
+Message-ID: <1@test>
+Content-Type: text/plain; charset=utf-8
+Content-Transfer-Encoding: base64
+
+VGVzdCBtaXQgQmFzZTY0LUtvZGllcnVuZzogw6TDtsO8w58='''
+
+        result = async_to_sync(handler.handle_DATA)(server, session, envelope)
+        self.assertEqual(result, '250 Message accepted for delivery')
+        self.assertEqual(len(Email.objects.all()), 2)
+        self.assertEqual(len(IssueThread.objects.all()), 1)
+        aiosmtplib.send.assert_called_once()
+        self.assertEqual('test', Email.objects.all()[0].subject)
+        self.assertEqual('Test mit Base64-Kodierung: äöüß', Email.objects.all()[0].body)
+        self.assertTrue(Email.objects.all()[0].raw_file.path)
+
     def test_handle_client_reply(self):
         issue_thread = IssueThread.objects.create(
             name="test",