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 ?÷     #! /usr/bin/python
"""An RFC 2821 smtp proxy.

Usage: %(program)s [options] [localhost:localport [remotehost:remoteport]]

Options:

    --nosetuid
    -n
        This program generally tries to setuid `nobody', unless this flag is
        set.  The setuid call will fail if this program is not run as root (in
        which case, use this flag).

    --version
    -V
        Print the version number and exit.

    --class classname
    -c classname
        Use `classname' as the concrete SMTP proxy class.  Uses `PureProxy' by
        default.

    --debug
    -d
        Turn on debugging prints.

    --help
    -h
        Print this message and exit.

Version: %(__version__)s

If localhost is not given then `localhost' is used, and if localport is not
given then 8025 is used.  If remotehost is not given then `localhost' is used,
and if remoteport is not given, then 25 is used.
"""

# Overview:
#
# This file implements the minimal SMTP protocol as defined in RFC 821.  It
# has a hierarchy of classes which implement the backend functionality for the
# smtpd.  A number of classes are provided:
#
#   SMTPServer - the base class for the backend.  Raises NotImplementedError
#   if you try to use it.
#
#   DebuggingServer - simply prints each message it receives on stdout.
#
#   PureProxy - Proxies all messages to a real smtpd which does final
#   delivery.  One known problem with this class is that it doesn't handle
#   SMTP errors from the backend server at all.  This should be fixed
#   (contributions are welcome!).
#
#   MailmanProxy - An experimental hack to work with GNU Mailman
#   <www.list.org>.  Using this server as your real incoming smtpd, your
#   mailhost will automatically recognize and accept mail destined to Mailman
#   lists when those lists are created.  Every message not destined for a list
#   gets forwarded to a real backend smtpd, as with PureProxy.  Again, errors
#   are not handled correctly yet.
#
# Please note that this script requires Python 2.0
#
# Author: Barry Warsaw <barry@python.org>
#
# TODO:
#
# - support mailbox delivery
# - alias files
# - ESMTP
# - handle error codes from the backend smtpd

import sys
import os
import errno
import getopt
import time
import socket
import asyncore
import asynchat

__all__ = ["SMTPServer","DebuggingServer","PureProxy","MailmanProxy"]

program = sys.argv[0]
__version__ = 'Python SMTP proxy version 0.2'


class Devnull:
    def write(self, msg): pass
    def flush(self): pass


DEBUGSTREAM = Devnull()
NEWLINE = '\n'
EMPTYSTRING = ''
COMMASPACE = ', '


def usage(code, msg=''):
    print >> sys.stderr, __doc__ % globals()
    if msg:
        print >> sys.stderr, msg
    sys.exit(code)


class SMTPChannel(asynchat.async_chat):
    COMMAND = 0
    DATA = 1

    def __init__(self, server, conn, addr):
        asynchat.async_chat.__init__(self, conn)
        self.__server = server
        self.__conn = conn
        self.__addr = addr
        self.__line = []
        self.__state = self.COMMAND
        self.__greeting = 0
        self.__mailfrom = None
        self.__rcpttos = []
        self.__data = ''
        self.__fqdn = socket.getfqdn()
        try:
            self.__peer = conn.getpeername()
        except socket.error, err:
            # a race condition  may occur if the other end is closing
            # before we can get the peername
            self.close()
            if err[0] != errno.ENOTCONN:
                raise
            return
        print >> DEBUGSTREAM, 'Peer:', repr(self.__peer)
        self.push('220 %s %s' % (self.__fqdn, __version__))
        self.set_terminator('\r\n')

    # Overrides base class for convenience
    def push(self, msg):
        asynchat.async_chat.push(self, msg + '\r\n')

    # Implementation of base class abstract method
    def collect_incoming_data(self, data):
        self.__line.append(data)

    # Implementation of base class abstract method
    def found_terminator(self):
        line = EMPTYSTRING.join(self.__line)
        print >> DEBUGSTREAM