src/mailman/mta/connection.py

   1 # Copyright (C) 2009-2016 by the Free Software Foundation, Inc.
   2 #
   3 # This file is part of GNU Mailman.
   4 #
   5 # GNU Mailman is free software: you can redistribute it and/or modify it under
   6 # the terms of the GNU General Public License as published by the Free
   7 # Software Foundation, either version 3 of the License, or (at your option)
   8 # any later version.
   9 #
  10 # GNU Mailman is distributed in the hope that it will be useful, but WITHOUT
  11 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13 # more details.
  14 #
  15 # You should have received a copy of the GNU General Public License along with
  16 # GNU Mailman.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 """MTA connections."""
  19
  20 import logging
  21 import smtplib
  22
  23 from contextlib import suppress
  24 from lazr.config import as_boolean
  25 from mailman import public
  26 from mailman.config import config
  27
  28
  29 log = logging.getLogger('mailman.smtp')
  30
  31
  32 @public
  33 class Connection:
  34     """Manage a connection to the SMTP server."""
  35     def __init__(self, host, port, sessions_per_connection,
  36                  smtp_user=None, smtp_pass=None):
  37         """Create a connection manager.
  38
  39         :param host: The host name of the SMTP server to connect to.
  40         :type host: string
  41         :param port: The port number of the SMTP server to connect to.
  42         :type port: integer
  43         :param sessions_per_connection: The number of SMTP sessions per
  44             connection to the SMTP server.  After this number of sessions
  45             has been reached, the connection is closed and a new one is
  46             opened.  Set to zero for an unlimited number of sessions per
  47             connection (i.e. your MTA has no limit).
  48         :type sessions_per_connection: integer
  49         :param smtp_user: Optional SMTP authentication user name.  If given,
  50             `smtp_pass` must also be given.
  51         :type smtp_user: str
  52         :param smtp_pass: Optional SMTP authentication password.  If given,
  53             `smtp_user` must also be given.
  54         """
  55         self._host = host
  56         self._port = port
  57         self._sessions_per_connection = sessions_per_connection
  58         self._username = smtp_user
  59         self._password = smtp_pass
  60         self._session_count = None
  61         self._connection = None
  62
  63     def _connect(self):
  64         """Open a new connection."""
  65         self._connection = smtplib.SMTP()
  66         log.debug('Connecting to %s:%s', self._host, self._port)
  67         self._connection.connect(self._host, self._port)
  68         if self._username is not None and self._password is not None:
  69             log.debug('Logging in')
  70             self._connection.login(self._username, self._password)
  71         self._session_count = self._sessions_per_connection
  72
  73     def sendmail(self, envsender, recipients, msgtext):
  74         """Mimic `smtplib.SMTP.sendmail`."""
  75         if as_boolean(config.devmode.enabled):
  76             # Force the recipients to the specified address, but still deliver
  77             # to the same number of recipients.
  78             recipients = [config.devmode.recipient] * len(recipients)
  79         if self._connection is None:
  80             self._connect()
  81         try:
  82             log.debug('envsender: %s, recipients: %s, size(msgtext): %s',
  83                       envsender, recipients, len(msgtext))
  84             results = self._connection.sendmail(envsender, recipients, msgtext)
  85         except smtplib.SMTPException:
  86             # For safety, close this connection.  The next send attempt will
  87             # automatically re-open it.  Pass the exception on up.
  88             self.quit()
  89             raise
  90         # This session has been successfully completed.
  91         self._session_count -= 1
  92         # By testing exactly for equality to 0, we automatically handle the
  93         # case for SMTP_MAX_SESSIONS_PER_CONNECTION <= 0 meaning never close
  94         # the connection.  We won't worry about wraparound <wink>.
  95         if self._session_count == 0:
  96             self.quit()
  97         return results
  98
  99     def quit(self):
 100         """Mimic `smtplib.SMTP.quit`."""
 101         if self._connection is None:
 102             return
 103         with suppress(smtplib.SMTPException):
 104             self._connection.quit()
 105         self._connection = None