From 8e2a22a6f1803ef693426a0cdfdab804a5d3ee20 Mon Sep 17 00:00:00 2001
From: s3lph <1375407-s3lph@users.noreply.gitlab.com>
Date: Wed, 13 Apr 2022 01:21:45 +0200
Subject: [PATCH] Initial commit

---
 .gitignore        |   2 +
 multischleuder.py | 404 ++++++++++++++++++++++++++++++++++++++++++++++
 requirements.txt  |   3 +
 3 files changed, 409 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 multischleuder.py
 create mode 100644 requirements.txt

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..aaf927b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+ca.pem
+multischleuder.yml
\ No newline at end of file
diff --git a/multischleuder.py b/multischleuder.py
new file mode 100644
index 0000000..bd16524
--- /dev/null
+++ b/multischleuder.py
@@ -0,0 +1,404 @@
+#!/usr/bin/env python3
+
+
+from typing import Any, Dict, List, Optional
+
+import argparse
+import base64
+import email
+import json
+import logging
+import os
+import re
+import urllib.request
+import smtplib
+import ssl
+import sys
+import hashlib
+
+import yaml
+import pgpy
+
+from dataclasses import dataclass, field, Field
+from datetime import datetime
+from dateutil.parser import isoparse
+
+
+LOG: logging.Logger = logging.getLogger('multischleuder')
+
+
+class SmtpServerConfig:
+    
+    def __init__(self, hostname: str, port: int, tls: bool, username: str, password: str):
+        self.hostname = hostname
+        self.port = port
+        self.tls = tls
+        self.username = username
+        self.password = password
+        self._smtp = None
+
+    @staticmethod
+    def parse(config: Dict[str, Any]) -> 'SmtpServerConfig':
+        tls = config.get('tls', 'PLAIN')
+        port = {
+            'SSL': 465,
+            'STARTTLS': 587
+        }.get(tls, 25)
+        return SmtpServerConfig(
+            hostname=config['hostname'],
+            port=config.get('port', port),
+            tls=tls,
+            username=config.get('username'),
+            password=config.get('password')
+        )
+
+    def __enter__(self):
+        cls = smtplib.SMTP if self.tls != 'SSL' else smtplib.SMTP_SSL
+        self._smtp = cls(self.hostname, self.port)
+        smtp = self._smtp.__enter__()
+        if self.tls == 'STARTTLS':
+            smtp.starttls()
+        if self.username is not None and self.password is not None:
+            smtp.login(self.username, self.password)
+        return smtp
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        ret = self._smtp.__exit__(exc_type, exc_val, exc_tb)
+        self._smtp = None
+        return ret
+
+    def send_message(self, msg):
+        if self._smtp is None:
+            raise RuntimeError('SMTP connection is not established')
+        self._smtp.send_message(msg)
+
+
+
+@dataclass
+class SchleuderSubscriber:
+    email: str
+    key: 'SchleuderKey'
+    sub_id: int
+    schleuder: 'SchleuderList'
+    created_at: datetime
+
+    def __str__(self) -> str:
+        return f'{self.email}'
+
+    def __hash__(self) -> int:
+        return hash(self.email)
+
+    def __eq__(self, o) -> bool:
+        if not isinstance(o, SchleuderSubscriber):
+            return False
+        return self.email == o.email
+
+
+@dataclass
+class SchleuderKey:
+    fingerprint: str
+    email: str
+    blob: Optional[str] = field(repr=False, default=None)
+    source_list: int
+
+    def __hash__(self) -> int:
+        return hash((self.fingerprint, self.email))
+
+    def __str__(self) -> str:
+        return f'{self.fingerprint} ({self.email})'
+
+
+@dataclass
+class SchleuderList:
+    id: int
+    name: str
+    fingerprint: str
+
+    def __hash__(self) -> int:
+        return hash(self.id)
+
+
+class ConflictMessage:
+
+    def __init__(self,
+                 multilist: 'MultiList',
+                 chosen: 'SchleuderSubscriber',
+                 affected: List['SchleuderSubscriber']):
+        self.multlist = multilist
+        self.chosen = chosen
+        self.affected = affected
+        # Generate a SHA1 digest that only changes when the subscription list changes
+        self.affected.sort(key=lambda x: x.created_at)
+        digest = hashlib.new('sha1')
+        digest.update(self.chosen.email)
+        digest.update(self.chosen.scheluder.name)
+        for affected in self.affected:
+            digest.update(affected.scheluder.name)
+            digest.update(affected.key.blob)
+        self.now = datetime.utcnow()
+        self.digest = digest.hexdigest()
+
+    def to_mime(self):
+        _chosen = f'{self.chosen.key.fingerprint}  {self.chosen.email}'
+        for affected in self.affected:
+            _affected += f'{affected.key.fingerprint}  {affected.schleuder.name}\n'
+        msg = self.multilist.conflict_message.format(
+            subscriber=self.chosen.email,
+            schleuder=self.multilist.list,
+            chosen=_chosen,
+            affected=_affected
+        )
+        pgp = pgpy.PGPMessage.new(msg)
+        # Encrypt the message to all keys
+        cipher = pgpy.constants.SymmetricKeyAlgorithm.AES256
+        sessionkey = cipher.gen_key()
+        try:
+            for affected in self.affected:
+                key, _ = pgpy.PGPKey.from_blob(self.affected.key.blob)
+                key._require_usage_flags = False
+                pgp = key.encrypt(pgp, cipher=cipher, sessionkey=sessionkey)
+        finally:
+            del sessionkey
+        # Build the MIME message
+        mp1 = email.mime.application.MIMEApplication('Version: 1', _subtype='pgp-encrypted')
+        mp1['Content-Description'] = 'PGP/MIME version identification'
+        mp1['Content-Disposition'] = 'attachment'
+        mp2 = email.mime.application.MIMEApplication(str(pgp), _subtype='octet-stream', name='encrypted.asc')
+        mp2['Content-Description'] = 'OpenPGP encrypted message'
+        mp2['Content-Disposition'] = 'inline; filename="message.asc"'
+        mp0 = email.mime.multipart.MIMEMultipart(_subtype='encrypted', protocol='application/pgp-encrypted')
+        mp0.attach(mp1)
+        mp0.attach(mp2)
+        mp0['Subject'] = f'MultiSchleuder {self.multilist.name} - Key Conflict'
+        mp0['From'] = self.multilist.conflict_from
+        mp0['Reply-To'] = self.multilist.conflict_from
+        mp0['To'] = self.chosen.address
+        mp0['Date'] = email.util.formatdate(self.no)
+        mp0['Auto-Submitted'] = 'auto-generated'
+        mp0['Precedence'] = 'list'
+        mp0['List-Id'] = f'<{self.multilist.list.replace("@", ".")}>'
+        mp0['List-Help'] = '<https://gitlab.com/s3lph/multischleuder>'
+        mp0['X-MultiSchleuder-Digest'] = self.digest
+        return mp0
+        
+        
+class MultiList:
+
+    def __init__(self,
+                 ns: argparse.Namespace,
+                 list: str,
+                 source: List[str],
+                 unmanaged: List[str],
+                 banned: List[str],
+                 from_address: str,
+                 api_url: str,
+                 api_token: str,
+                 api_cafile: str,
+                 conflict_state_file: str,
+                 conflict_message: str,
+                 conflict_interval: int,
+                 conflict_smtp: SmtpServerConfig):
+        self.ns: argparse.Namespace = ns
+        self.list: str = list
+        self.source: List[str] = source
+        self.unmanaged: List[str] = unmanaged
+        self.banned: List[str] = banned
+        self.api_url: str = api_url
+        self.basic_auth = {'Authorization': b'Basic ' + base64.b64encode(f'schleuder:{api_token}'.encode())}
+        self.api_cafile: str = api_cafile
+        self.conflict_messages = []
+        self.conflict_from = from_address
+        self.conflict_state_file: str = conflict_state_file
+        self.conflict_message: str = conflict_message
+        self.conflict_interval: int = conflict_interval
+        self.conflict_smtp: SmtpServerConfig = conflict_smtp
+
+    def request(self, path: str, list_id: Optional[int] = None, data: Optional[str] = None, method: str = 'GET', fmt=[]):
+        if fmt:
+            path = path.format(*fmt)
+        url = os.path.join(self.api_url, path)
+        if list_id is not None:
+            url += f'?list_id={list_id}'
+        payload: Optional[bytes] = data.encode() if data is not None else None
+        context = ssl.create_default_context(cafile=self.api_cafile)
+        context.check_hostname = False
+        req = urllib.request.Request(url, data=payload, method=method, headers=self.basic_auth)
+        resp = urllib.request.urlopen(req, context=context)
+        return json.loads(resp.read().decode())
+
+    def resolve_lists(self) -> Dict[str, 'SchleuderList']:
+        response = self.request('lists.json')
+        lists = {}
+        for r in response:
+            l = SchleuderList(r['id'], r['email'], r['fingerprint'])
+            if l.name == self.list or l.name in self.source:
+                lists[l.name] = l
+        return lists
+
+    def get_list_subscribers(self, list: 'SchleuderList') -> Dict[str, 'SchleuderSubscriber']:
+        response = self.request('subscriptions.json', list.id)
+        subs = {}
+        for r in response:
+            key = SchleuderKey(r['fingerprint'], r['email'], list.id)
+            sub = SchleuderSubscriber(r['email'], key, isoparse(r['created_at']), list, r['id'])
+            subs[sub.email] = sub
+        return subs
+
+    def get_key(self, key: 'SchleuderKey') -> 'SchleuderKey':
+        if key.blob is not None:
+            return key
+        r = self.request('keys/{}.json', list_id=key.source_list, fmt=[key.fingerprint])
+        key.blob = r['ascii']
+        return key
+
+    def post_key(self, key: 'SchleuderKey', list: 'SchleuderList'):
+        if self.ns.dry_run:
+            return
+        if not key.blob:
+            raise RuntimeError('Key blob needs to be retrieved first')
+        data = json.dumps({
+            'keymaterial': key.blob
+        })
+        self.request('keys.json', list_id=list.id, data=data, method='POST')
+
+    def delete_key(self, key: SchleuderKey, list: 'SchleuderList'):
+        if self.ns.dry_run:
+            return
+        self.request('keys/{}.json', list_id=list.id, fmt=[key.fingerprint], method='DELETE')
+
+    def subscribe(self, sub: 'SchleuderSubscriber', list: 'SchleuderList'):
+        if self.ns.dry_run:
+            return
+        data = json.dumps({
+            'email': sub.email,
+            'fingerprint': sub.key.fingerprint
+        })
+        self.request('subscriptions.json', list_id=list.id, data=data, method='POST')
+
+    def unsubscribe(self, sub: 'SchleuderSubscriber'):
+        if self.ns.dry_run:
+            return
+        self.request('subscriptions/{}.json', fmt=[sub.sub_id], method='DELETE')
+
+    def resolve_subscriber_conflicts(self, subscriptions: List['SchleuderSubscription']) -> 'SchleuderSubscription':
+        if len(subscriptions) == 1:
+            return subscriptions[0]
+        earliest = min(subscriptions, key=lambda x: x.created_at)
+        LOG.debug(f'Key Conflict for {earliest.email} in lists, chose {earliest.schleuder.name}:')
+        for s in subscriptions:
+            LOG.debug(f'  - {s.schleuder.name}: {s.key.fingerprint}')
+        for s in subscriptions:
+            self.get_key(s.key, s.list.id)
+        self.conflict_messages.append(ConflictMessage(earliest, subscriptions))
+        return earliest
+
+    def send_conflict_messages(self):
+        now = datetime.utcnow().timestamp()
+        with open(self.conflict_state_file, 'a+') as f:
+            f.seek(0)
+            state = json.load(f)
+            # Remove all state entries older than conflict_interval
+            state = {k: v for k, v in state.items() if now-v < self.conflict_interval}
+            # Remove all messages not already sent recently
+            msgs = [m for m in self.conflict_messages if m.digest not in state]
+            # Add all remaining messages to state dict
+            for m in msgs:
+                state[m.digest] = now
+            if not self.ns.dry_run:
+                f.seek(0)
+                f.truncate()
+                json.dump(state)
+        # Finally send the mails
+        for m in msgs:
+            LOG.info(f'Sending key conflict message to {m["To"]}')
+            LOG.debug(f'MIME Message:\n{str(m)}')
+            if not self.ns.dry_run:
+                with self.smtp_config as smtp:
+                    smtp.send_message(m)
+        # Clear conflict messages
+        self.conflict_messages = []
+
+    def process(self):
+        LOG.info(f'Processing: {self.list} {"DRY RUN" if self.ns.dry_run else ""}')
+        # todo: conflict handling - what if a user is subscribed through 2 lists (and possibly with different keys?)
+        lists: Dict[str, SchleuderList] = self.resolve_lists()
+        target_list = lists[self.list]
+        # Get current subs, except for unmanaged adresses
+        current_subs = {s
+                        for s in self.get_list_subscribers(target_list).values()
+                        if s.email not in self.unmanaged}
+        current_keys = {s.key for s in current_subs}
+        intended_subs = set()
+        intended_keys = set()
+        all_subs = dict()
+        # This loop may return multiple subscriptions for some users if they are subscribed on multiple sub-lists
+        for source in self.source:
+            for sub in self.get_list_subscribers(lists[source]).values():
+                # Don't include banned or unmanaged adresses
+                if sub.email in self.banned or s.email in self.unmanaged:
+                    continue
+                all_subs.setdefault(sub.email, []).append(sub)
+        # Remove 
+        for subs in all_subs.values():
+            sub = self.resolve_subscriber_conflicts(subs)
+            intended_subs.add(sub)
+            intended_keys.add(sub.key)
+        # Determine the change set
+        to_subscribe = intended_subs.difference(current_subs)
+        to_unsubscribe = current_subs.difference(intended_subs)
+        to_remove = current_keys.difference(intended_keys)
+        to_add = intended_keys.difference(current_keys)
+        # Retrieve actual key blobs
+        for key in to_add:
+            self.get_key(key)
+        # Perform the actual list modifications in an order where nothing breaks
+        for key in to_add:
+            self.post_key(key, target_list_id)
+            LOG.info(f'Added key: {key}')
+        for email in to_subscribe:
+            self.subscribe(email, target_list_id)
+            LOG.info(f'Subscribed user: {email}')
+        for sub_id in to_unsubscribe:
+            self.unsubscribe(sub_id)
+            LOG.info(f'Unsubscribed user: {sub_id}')
+        for key in to_remove:
+            self.delete_key(key, target_list_id)
+            LOG.info(f'Removed key: {key}')
+        self.send_conflict_messages()
+        if len(to_add) + len(to_subscribe) + len(to_unsubscribe) + len(to_remove) == 0:
+            LOG.info(f'No changes for {self.list}')
+        else:
+            LOG.info(f'Finished processing: {self.list}')
+
+
+def parse_config(ns: argparse.Namespace) -> List['MultiList']:
+    with open(ns.config, 'r') as f:
+        y = yaml.safe_load(f)
+    lists = []
+    for l in y['lists']:
+        lc = MultiList(ns,
+                       l['name'], l['source'], l.get('unmanaged', []), l.get('banned', []),
+                       l.get('from'),
+                       y['api']['url'], y['api']['token'], y['api']['cafile'],
+                       y['conflict']['state'], y['conflict']['message'], y['conflict']['interval'],
+                       SmtpServerConfig.parse(y['conflict']['smtp']))
+        lists.append(lc)
+    return lists
+
+
+def main():
+    ap = argparse.ArgumentParser()
+    ap.add_argument('--config', '-c', type=str, default='/etc/multischleuder/config.yml')
+    ap.add_argument('--dry-run', '-n', action='store_true', default=False)
+    ap.add_argument('--verbose', '-v', action='store_true', default=False)
+    ns = ap.parse_args(sys.argv[1:])
+    if ns.verbose:
+        LOG.setLevel('DEBUG')
+        LOG.debug('Enabled verbose logging')
+    lists = parse_config(ns)
+    for l in lists:
+        l.process()
+
+
+if __name__ == '__main__':
+    main()
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..019e87a
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,3 @@
+dateutil
+PyYAML
+PGPy