144 lines
4.5 KiB
Python
144 lines
4.5 KiB
Python
import asyncio
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# Though we don't use requests, without the below import, we crash https://stackoverflow.com/a/13057751
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# When running on privilege port after dropping privileges.
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# noinspection PyUnresolvedReferences
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import encodings.idna
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import io
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import logging
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import mailbox
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import os
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import ssl
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import sys
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from argparse import ArgumentParser
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from functools import partial
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from pathlib import Path
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from aiosmtpd.controller import Controller
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from aiosmtpd.handlers import Mailbox
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from aiosmtpd.main import DATA_SIZE_DEFAULT
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from aiosmtpd.smtp import SMTP
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from .pop3 import a_main as pop3_main
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def create_tls_context(certfile, keyfile):
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context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
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context.load_cert_chain(certfile=certfile, keyfile=keyfile)
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return context
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class STARTTLSController(Controller):
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def __init__(self, *args, tls_context, smtp_args=None, **kwargs):
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self.tls_context = tls_context
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self.smtp_args = smtp_args or {}
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self.has_privileges_dropped: asyncio.Future = None
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if 'ssl_context' in kwargs:
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raise Exception("ssl_context not allowed when using STARTTLS, set tls_context instead")
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Controller.__init__(self, *args, **kwargs)
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async def create_future(self):
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self.has_privileges_dropped = asyncio.get_event_loop().create_future()
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async def wait_for_privileges_to_drop(self):
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await self.has_privileges_dropped
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def factory(self):
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if not self.has_privileges_dropped.done():
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# Ideally we should await here. But this is callback and not a coroutine
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raise Exception("Client connected too fast before we could drop root privileges")
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return SMTP(self.handler, require_starttls=True, tls_context=self.tls_context, **self.smtp_args)
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class MaildirCRLF(mailbox.Maildir):
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_append_newline = True
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def _dump_message(self, message, target, mangle_from_=False):
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temp_buffer = io.BytesIO()
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super()._dump_message(message, temp_buffer, mangle_from_=mangle_from_)
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temp_buffer.seek(0)
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data = temp_buffer.read()
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data = data.replace(b'\n', b'\r\n')
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target.write(data)
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class MailboxCRLF(Mailbox):
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def __init__(self, mail_dir: Path):
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super().__init__(mail_dir)
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for sub in ('new', 'tmp', 'cur'):
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sub_path = mail_dir / sub
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sub_path.mkdir(mode=0o755, exist_ok=True, parents=True)
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self.mailbox = MaildirCRLF(mail_dir)
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def parse_args():
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parser = ArgumentParser()
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parser.add_argument('--certfile')
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parser.add_argument('--keyfile')
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parser.add_argument("mail_dir_path")
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args = parser.parse_args()
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args.mail_dir_path = Path(args.mail_dir_path)
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# Hardcoded args
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args.host = '0.0.0.0'
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args.smtp_port = 25
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args.pop_port = 995
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args.size = DATA_SIZE_DEFAULT
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args.classpath = MailboxCRLF
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args.smtputf8 = True
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args.debug = True
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return args
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def setup_logging(args):
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if args.debug:
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logging.basicConfig(level=logging.DEBUG)
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else:
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logging.basicConfig(level=logging.INFO)
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def drop_privileges(future_cb):
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try:
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import pwd
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except ImportError:
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logging.error("Cannot import pwd; run as root")
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sys.exit(1)
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nobody = pwd.getpwnam('nobody')
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try:
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os.setgid(nobody.pw_gid)
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os.setuid(nobody.pw_uid)
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except PermissionError:
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logging.error("Cannot setuid nobody; run as root")
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sys.exit(1)
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logging.info("Dropped privileges")
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future_cb().set_result("Go!")
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logging.debug("Signalled! Clients can come in")
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def main():
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args = parse_args()
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tls_context = create_tls_context(args.certfile, args.keyfile)
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smtp_args = dict(data_size_limit=args.size, enable_SMTPUTF8=args.smtputf8)
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setup_logging(args)
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handler = args.classpath(args.mail_dir_path)
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loop = asyncio.get_event_loop()
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loop.set_debug(args.debug)
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controller = STARTTLSController(
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handler, tls_context=tls_context, smtp_args=smtp_args, hostname=args.host, port=args.smtp_port, loop=loop)
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loop.create_task(controller.create_future())
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loop.create_task(pop3_main(args.mail_dir_path, args.pop_port,
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host=args.host, context=tls_context, waiter=controller.wait_for_privileges_to_drop()))
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controller.start()
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loop.call_soon_threadsafe(partial(drop_privileges, lambda: controller.has_privileges_dropped))
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logging.info("Server started. Press [ENTER] to stop")
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input()
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controller.stop()
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# loop.create_task(a_main(controller))
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# loop.run_forever()
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if __name__ == '__main__':
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main()
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