1 files changed, 184 insertions, 0 deletions
diff --git a/src/mailman/handlers/subject_prefix.py b/src/mailman/handlers/subject_prefix.py
new file mode 100644
index 000000000..20abd1036
--- /dev/null
+++ b/src/mailman/handlers/subject_prefix.py
@@ -0,0 +1,184 @@
+# Copyright (C) 2014 by the Free Software Foundation, Inc.
+#
+# This file is part of GNU Mailman.
+#
+# GNU Mailman is free software: you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option)
+# any later version.
+#
+# GNU Mailman 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 General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# GNU Mailman.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Subject header prefix munging."""
+
+__all__ = [
+    'SubjectPrefix',
+    ]
+
+
+import re
+
+from email.header import Header, make_header, decode_header
+from mailman.core.i18n import _
+from mailman.interfaces.handler import IHandler
+from zope.interface import implementer
+
+
+RE_PATTERN = '((RE|AW|SV|VS)(\[\d+\])?:\s*)+'
+ASCII_CHARSETS = (None, 'ascii', 'us-ascii')
+EMPTYSTRING = ''
+
+
+
+def ascii_header(mlist, msgdata, subject, prefix, prefix_pattern, ws):
+    if mlist.preferred_language.charset not in ASCII_CHARSETS:
+        return None
+    for chunk, charset in decode_header(subject.encode()):
+        if charset not in ASCII_CHARSETS:
+            return None
+    subject_text = EMPTYSTRING.join(str(subject).splitlines())
+    rematch = re.match(RE_PATTERN, subject_text, re.I)
+    if rematch:
+        subject_text = subject_text[rematch.end():]
+        recolon = 'Re: '
+    else:
+        recolon = ''
+    # At this point, the subject may become null if someone posted mail
+    # with "Subject: [subject prefix]".
+    if subject_text.strip() == '':
+        with _.using(mlist.preferred_language.code):
+            subject_text = _('(no subject)')
+    else:
+        subject_text = re.sub(prefix_pattern, '', subject_text)
+    msgdata['stripped_subject'] = subject_text
+    lines = subject_text.splitlines()
+    first_line = [lines[0]]
+    if recolon:
+        first_line.insert(0, recolon)
+    if prefix:
+        first_line.insert(0, prefix)
+    subject_text = EMPTYSTRING.join(first_line)
+    return Header(subject_text, continuation_ws=ws)
+
+
+def all_same_charset(mlist, msgdata, subject, prefix, prefix_pattern, ws):
+    list_charset = mlist.preferred_language.charset
+    chunks = []
+    for chunk, charset in decode_header(subject.encode()):
+        if charset is None:
+            charset = 'us-ascii'
+        chunks.append(chunk.decode(charset))
+        if charset != list_charset:
+            return None
+    subject_text = EMPTYSTRING.join(chunks)
+    rematch = re.match(RE_PATTERN, subject_text, re.I)
+    if rematch:
+        subject_text = subject_text[rematch.end():]
+        recolon = 'Re: '
+    else:
+        recolon = ''
+    # At this point, the subject may become null if someone posted mail
+    # with "Subject: [subject prefix]".
+    if subject_text.strip() == '':
+        with _.push(mlist.preferred_language.code):
+            subject_text = _('(no subject)')
+    else:
+        subject_text = re.sub(prefix_pattern, '', subject_text)
+    msgdata['stripped_subject'] = subject_text
+    lines = subject_text.splitlines()
+    first_line = [lines[0]]
+    if recolon:
+        first_line.insert(0, recolon)
+    if prefix:
+        first_line.insert(0, prefix)
+    subject_text = EMPTYSTRING.join(first_line)
+    return Header(subject_text, charset=list_charset, continuation_ws=ws)
+
+
+def mixed_charsets(mlist, msgdata, subject, prefix, prefix_pattern, ws):
+    list_charset = mlist.preferred_language.charset
+    chunks = decode_header(subject.encode())
+    if len(chunks) == 0:
+        with _.push(mlist.preferred_language.code):
+            subject_text = _('(no subject)')
+        chunks = [(prefix, list_charset),
+                  (subject_text, list_charset),
+                  ]
+        return make_header(chunks, continuation_ws=ws)
+    # Only search the first chunk for Re and existing prefix.
+    chunk_text, chunk_charset = chunks[0]
+    if chunk_charset is None:
+        chunk_charset = 'us-ascii'
+    first_text = chunk_text.decode(chunk_charset)
+    first_text = re.sub(prefix_pattern, '', first_text).lstrip()
+    rematch = re.match(RE_PATTERN, first_text, re.I)
+    if rematch:
+        first_text = 'Re: ' + first_text[rematch.end():]
+    chunks[0] = (first_text, chunk_charset)
+    # The subject text stripped of the prefix, for use in the NNTP gateway.
+    msgdata['stripped_subject'] = str(make_header(chunks, continuation_ws=ws))
+    chunks.insert(0, (prefix, list_charset))
+    return make_header(chunks, continuation_ws=ws)
+
+
+
+@implementer(IHandler)
+class SubjectPrefix:
+    """Add a list-specific prefix to the Subject header value."""
+
+    name = 'subject-prefix'
+    description = _('Add a list-specific prefix to the Subject header value.')
+
+    def process(self, mlist, msg, msgdata):
+        """See `IHandler`."""
+        if msgdata.get('isdigest') or msgdata.get('_fasttrack'):
+            return
+        prefix = mlist.subject_prefix
+        if not prefix.strip():
+            return
+        subject = msg.get('subject', '')
+        # Turn the value into a Header instance and try to figure out what
+        # continuation whitespace is being used.
+        # Save the original Subject.
+        msgdata['original_subject'] = subject
+        if isinstance(subject, Header):
+            subject_text = str(subject)
+        else:
+            subject = make_header(decode_header(subject))
+            subject_text = str(subject)
+        lines = subject_text.splitlines()
+        ws = '\t'
+        if len(lines) > 1 and lines[1] and lines[1][0] in ' \t':
+            ws = lines[1][0]
+        # If the subject_prefix contains '%d', it is replaced with the mailing
+        # list's sequence number.  The sequential number format allows '%d' or
+        # '%05d' like pattern.
+        prefix_pattern = re.escape(prefix)
+        # Unescape '%'.
+        prefix_pattern = '%'.join(prefix_pattern.split(r'\%'))
+        p = re.compile('%\d*d')
+        if p.search(prefix, 1):
+            # The prefix has number, so we should search prefix w/number in
+            # subject.  Also, force new style.
+            prefix_pattern = p.sub(r'\s*\d+\s*', prefix_pattern)
+        # Substitute %d in prefix with post_id
+        try:
+            prefix = prefix % mlist.post_id
+        except TypeError:
+            pass
+        for handler in (ascii_header,
+                        all_same_charset,
+                        mixed_charsets,
+                        ):
+            new_subject = handler(
+                mlist, msgdata, subject, prefix, prefix_pattern, ws)
+            if new_subject is not None:
+                del msg['subject']
+                msg['Subject'] = new_subject
+                return