[PATCH] parser: Unmangle From: headers that have been mangled for DMARC purposes
Andrew Donnellan
ajd at linux.ibm.com
Thu Oct 10 17:20:47 AEDT 2019
To avoid triggering spam filters due to failed signature validation, many
mailing lists mangle the From header to change the From address to be the
address of the list, typically where the sender's domain has a strict DMARC
policy enabled.
In this case, we should try to unmangle the From header.
Add support for using the X-Original-Sender or Reply-To headers, as used by
Google Groups and Mailman respectively, to unmangle the From header when
necessary.
Closes: #64 ("Incorrect submitter when using googlegroups")
Reported-by: Alexandre Belloni <alexandre.belloni at bootlin.com>
Reported-by: Stephen Rothwell <sfr at canb.auug.org.au>
Signed-off-by: Andrew Donnellan <ajd at linux.ibm.com>
---
patchwork/parser.py | 75 ++++++++++++++++++++++++++++++----
patchwork/tests/test_parser.py | 68 ++++++++++++++++++++++++++++--
2 files changed, 130 insertions(+), 13 deletions(-)
diff --git a/patchwork/parser.py b/patchwork/parser.py
index 7dc66bc05a5b..79beac5617b1 100644
--- a/patchwork/parser.py
+++ b/patchwork/parser.py
@@ -321,12 +321,7 @@ def find_series(project, mail, author):
return _find_series_by_markers(project, mail, author)
-def get_or_create_author(mail):
- from_header = clean_header(mail.get('From'))
-
- if not from_header:
- raise ValueError("Invalid 'From' header")
-
+def split_from_header(from_header):
name, email = (None, None)
# tuple of (regex, fn)
@@ -355,6 +350,65 @@ def get_or_create_author(mail):
(name, email) = fn(match.groups())
break
+ return (name, email)
+
+
+# Unmangle From addresses that have been mangled for DMARC purposes.
+#
+# To avoid triggering spam filters due to failed signature validation, many
+# mailing lists mangle the From header to change the From address to be the
+# address of the list, typically where the sender's domain has a strict
+# DMARC policy enabled.
+#
+# Unfortunately, there's no standardised way of preserving the original
+# From address.
+#
+# Google Groups adds an X-Original-Sender header. If present, we use that.
+#
+# Mailman preserves the original address by adding a Reply-To, except in the
+# case where the list is set to either reply to list, or reply to a specific
+# address, in which case the original From is added to Cc instead. These corner
+# cases are dumb, but we try and handle things as sensibly as possible by
+# looking for a name in Reply-To/Cc that matches From. It's inexact but should
+# be good enough for our purposes.
+def get_original_sender(mail, name, email):
+ if name and ' via ' in name:
+ # Mailman uses the format "<name> via <list>"
+ # Google Groups uses "'<name>' via <list>"
+ stripped_name = name[:name.rfind(' via ')].strip().strip("'")
+
+ original_sender = clean_header(mail.get('X-Original-Sender', ''))
+ if original_sender:
+ new_email = split_from_header(original_sender)[1].strip()[:255]
+ return (stripped_name, new_email)
+
+ addrs = []
+ reply_to_headers = mail.get_all('Reply-To') or []
+ cc_headers = mail.get_all('Cc') or []
+ for header in reply_to_headers + cc_headers:
+ header = clean_header(header)
+ addrs = header.split(",")
+ for addr in addrs:
+ new_name, new_email = split_from_header(addr)
+ if new_name:
+ new_name = new_name.strip()[:255]
+ if new_email:
+ new_email = new_email.strip()[:255]
+ if new_name == stripped_name:
+ return (stripped_name, new_email)
+
+ # If we can't figure out the original sender, just keep it as is
+ return (name, email)
+
+
+def get_or_create_author(mail, project=None):
+ from_header = clean_header(mail.get('From'))
+
+ if not from_header:
+ raise ValueError("Invalid 'From' header")
+
+ name, email = split_from_header(from_header)
+
if not email:
raise ValueError("Invalid 'From' header")
@@ -362,6 +416,9 @@ def get_or_create_author(mail):
if name is not None:
name = name.strip()[:255]
+ if project and email.lower() == project.listemail.lower():
+ name, email = get_original_sender(mail, name, email)
+
# this correctly handles the case where we lose the race to create
# the person and another process beats us to it. (If the record
# does not exist, g_o_c invokes _create_object_from_params which
@@ -1004,7 +1061,7 @@ def parse_mail(mail, list_id=None):
if not is_comment and (diff or pull_url): # patches or pull requests
# we delay the saving until we know we have a patch.
- author = get_or_create_author(mail)
+ author = get_or_create_author(mail, project)
delegate = find_delegate_by_header(mail)
if not delegate and diff:
@@ -1099,7 +1156,7 @@ def parse_mail(mail, list_id=None):
is_cover_letter = True
if is_cover_letter:
- author = get_or_create_author(mail)
+ author = get_or_create_author(mail, project)
# we don't use 'find_series' here as a cover letter will
# always be the first item in a thread, thus the references
@@ -1159,7 +1216,7 @@ def parse_mail(mail, list_id=None):
if not submission:
return
- author = get_or_create_author(mail)
+ author = get_or_create_author(mail, project)
try:
comment = Comment.objects.create(
diff --git a/patchwork/tests/test_parser.py b/patchwork/tests/test_parser.py
index e5a2fca3044e..85c6e7550f93 100644
--- a/patchwork/tests/test_parser.py
+++ b/patchwork/tests/test_parser.py
@@ -265,11 +265,23 @@ class SenderCorrelationTest(TestCase):
"""
@staticmethod
- def _create_email(from_header):
+ def _create_email(from_header, reply_tos=None, ccs=None,
+ x_original_sender=None):
mail = 'Message-Id: %s\n' % make_msgid() + \
- 'From: %s\n' % from_header + \
- 'Subject: Tests\n\n'\
- 'test\n'
+ 'From: %s\n' % from_header
+
+ if reply_tos:
+ mail += 'Reply-To: %s\n' % ', '.join(reply_tos)
+
+ if ccs:
+ mail += 'Cc: %s\n' % ', '.join(ccs)
+
+ if x_original_sender:
+ mail += 'X-Original-Sender: %s\n' % x_original_sender
+
+ mail += 'Subject: Tests\n\n'\
+ 'test\n'
+
return message_from_string(mail)
def test_existing_sender(self):
@@ -311,6 +323,54 @@ class SenderCorrelationTest(TestCase):
self.assertEqual(person_b._state.adding, False)
self.assertEqual(person_b.id, person_a.id)
+ def test_mailman_dmarc_munging(self):
+ project = create_project()
+ real_sender = 'Existing Sender <existing at example.com>'
+ munged_sender = 'Existing Sender via List <{}>'.format(
+ project.listemail)
+ other_email = 'Other Person <other at example.com>'
+
+ # Unmunged author
+ mail = self._create_email(real_sender)
+ person_a = get_or_create_author(mail, project)
+ person_a.save()
+
+ # Single Reply-To
+ mail = self._create_email(munged_sender, [real_sender])
+ person_b = get_or_create_author(mail, project)
+ self.assertEqual(person_b._state.adding, False)
+ self.assertEqual(person_b.id, person_a.id)
+
+ # Single Cc
+ mail = self._create_email(munged_sender, [], [real_sender])
+ person_b = get_or_create_author(mail, project)
+ self.assertEqual(person_b._state.adding, False)
+ self.assertEqual(person_b.id, person_a.id)
+
+ # Multiple Reply-Tos and Ccs
+ mail = self._create_email(munged_sender, [other_email, real_sender],
+ [other_email, other_email])
+ person_b = get_or_create_author(mail, project)
+ self.assertEqual(person_b._state.adding, False)
+ self.assertEqual(person_b.id, person_a.id)
+
+ def test_google_dmarc_munging(self):
+ project = create_project()
+ real_sender = 'Existing Sender <existing at example.com>'
+ munged_sender = "'Existing Sender' via List <{}>".format(
+ project.listemail)
+
+ # Unmunged author
+ mail = self._create_email(real_sender)
+ person_a = get_or_create_author(mail, project)
+ person_a.save()
+
+ # X-Original-Sender header
+ mail = self._create_email(munged_sender, None, None, real_sender)
+ person_b = get_or_create_author(mail, project)
+ self.assertEqual(person_b._state.adding, False)
+ self.assertEqual(person_b.id, person_a.id)
+
class SeriesCorrelationTest(TestCase):
"""Validate correct behavior of find_series."""
--
2.20.1
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