usrbinenv python3 an rfc 5321 smtp proxy with optional rfc 1870 and rfc 6531 extensions usage programs 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 size limit s limit restrict the total size of the incoming message to limit number of bytes via the rfc 1870 size extension defaults to 33554432 bytes smtputf8 u enable the smtputf8 extension and behave as an rfc 6531 smtp proxy debug d turn on debugging prints help h print this message and exit version versions 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 5321 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 barry warsaw barrypython org todo support mailbox delivery alias files handle more esmtp extensions handle error codes from the backend smtpd a race condition may occur if the other end is closing before we can get the peername reset state variables to their postdata state self smtpstate self command self mailfrom none self rcpttos self requiresmtputf8 false self numbytes 0 self setterminatorb rn def setrsetstateself properties for backwardscompatibility overrides base class for convenience implementation of base class abstract method implementation of base class abstract method remove extraneous carriage returns and detransparency according to rfc 5321 section 4 5 2 smtp and esmtp commands see issue 21783 for a discussion of this behavior see issue 21783 for a discussion of this behavior args is ignored return params as dictionary return none if not all parameters appear to be syntactically valid according to rfc 1869 xxx currently there are no options we recognize commands that have not been implemented smtpchannel class to use for managing client connections try to reuse a server port if possible api for doing something useful with the message override this abstract method to handle messages from the client peer is a tuple containing ipaddr port of the client that made the socket connection to our smtp port mailfrom is the raw address the client claims the message is coming from rcpttos is a list of raw addresses the client wishes to deliver the message to data is a string containing the entire full text of the message headers if supplied and all it has been detransparencied according to rfc 821 section 4 5 2 in other words a line containing a followed by other text has had the leading dot removed kwargs is a dictionary containing additional information it is empty if decodedatatrue was given as init parameter otherwise it will contain the following keys mailoptions list of parameters to the mail command all elements are uppercase strings example body8bitmime smtputf8 rcptoptions same for the rcpt command this function should return none for a normal 250 ok response otherwise it should return the desired response string in rfc 821 format headers first decodeddatafalse make header match other binary output avoid spurious str on bytes instance warning look for the last header tbd what to do with refused addresses all recipients were refused if the exception had an associated error code use it otherwise fake it with a nontriggering exception code parse the rest of the arguments split into hostport pairs become nobody usr bin env python3 an rfc 5321 smtp proxy with optional rfc 1870 and rfc 6531 extensions 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 size limit s limit restrict the total size of the incoming message to limit number of bytes via the rfc 1870 size extension defaults to 33554432 bytes smtputf8 u enable the smtputf8 extension and behave as an rfc 6531 smtp proxy 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 5321 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 barry warsaw barry python org todo support mailbox delivery alias files handle more esmtp extensions handle error codes from the backend smtpd a race condition may occur if the other end is closing before we can get the peername reset state variables to their post data state reset all state variables except the greeting properties for backwards compatibility overrides base class for convenience implementation of base class abstract method implementation of base class abstract method remove extraneous carriage returns and de transparency according to rfc 5321 section 4 5 2 smtp and esmtp commands see issue 21783 for a discussion of this behavior see issue 21783 for a discussion of this behavior args is ignored return params as dictionary return none if not all parameters appear to be syntactically valid according to rfc 1869 xxx currently there are no options we recognize commands that have not been implemented smtpchannel class to use for managing client connections try to re use a server port if possible api for doing something useful with the message override this abstract method to handle messages from the client peer is a tuple containing ipaddr port of the client that made the socket connection to our smtp port mailfrom is the raw address the client claims the message is coming from rcpttos is a list of raw addresses the client wishes to deliver the message to data is a string containing the entire full text of the message headers if supplied and all it has been de transparencied according to rfc 821 section 4 5 2 in other words a line containing a followed by other text has had the leading dot removed kwargs is a dictionary containing additional information it is empty if decode_data true was given as init parameter otherwise it will contain the following keys mail_options list of parameters to the mail command all elements are uppercase strings example body 8bitmime smtputf8 rcpt_options same for the rcpt command this function should return none for a normal 250 ok response otherwise it should return the desired response string in rfc 821 format headers first decoded_data false make header match other binary output avoid spurious str on bytes instance warning look for the last header tbd what to do with refused addresses all recipients were refused if the exception had an associated error code use it otherwise fake it with a non triggering exception code parse the rest of the arguments split into host port pairs become nobody
import sys
import os
import errno
import getopt
import time
import socket
import collections
from test.support import asyncore, asynchat
from warnings import warn
from email._header_value_parser import get_addr_spec, get_angle_addr

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

program = sys.argv[0]
__version__ = 'Python SMTP proxy version 0.3'


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


DEBUGSTREAM = Devnull()
NEWLINE = '\n'
COMMASPACE = ', '
DATA_SIZE_DEFAULT = 33554432


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


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

    command_size_limit = 512
    command_size_limits = collections.defaultdict(lambda x=command_size_limit: x)

    @property
    def max_command_size_limit(self):
        try:
            return max(self.command_size_limits.values())
        except ValueError:
            return self.command_size_limit

    def __init__(self, server, conn, addr, data_size_limit=DATA_SIZE_DEFAULT,
                 map=None, enable_SMTPUTF8=False, decode_data=False):
        asynchat.async_chat.__init__(self, conn, map=map)
        self.smtp_server = server
        self.conn = conn
        self.addr = addr
        self.data_size_limit = data_size_limit
        self.enable_SMTPUTF8 = enable_SMTPUTF8
        self._decode_data = decode_data
        if enable_SMTPUTF8 and decode_data:
            raise ValueError("decode_data and enable_SMTPUTF8 cannot"
                             " be set to True at the same time")
        if decode_data:
            self._emptystring = ''
            self._linesep = '\r\n'
            self._dotsep = '.'
            self._newline = NEWLINE
        else:
            self._emptystring = b''
            self._linesep = b'\r\n'
            self._dotsep = ord(b'.')
            self._newline = b'\n'
        self._set_rset_state()
        self.seen_greeting = ''
        self.extended_smtp = False
        self.command_size_limits.clear()
        self.fqdn = socket.getfqdn()
        try:
            self.peer = conn.getpeername()
        except OSError as err:
            
            
            self.close()
            if err.errno != errno.ENOTCONN:
                raise
            return
        print('Peer:', repr(self.peer), file=DEBUGSTREAM)
        self.push('220 %s %s' % (self.fqdn, __version__))

    def _set_post_data_state(self):
        
        self.smtp_state = self.COMMAND
        self.mailfrom = None
        self.rcpttos = []
        self.require_SMTPUTF8 = False
        self.num_bytes = 0
        self.set_terminator(b'\r\n')

    def _set_rset_state(self):
        
        self._set_post_data_state()
        self.received_data = ''
        self.received_lines = []


    
    @property
    def __server(self):
        warn("Access to __server attribute on SMTPChannel is deprecated, "
            "use 'smtp_server' instead", DeprecationWarning, 2)
        return self.smtp_server
    @__server.setter
    def __server(self, value):
        warn("Setting __server attribute on SMTPChannel is deprecated, "
            "set 'smtp_server' instead", DeprecationWarning, 2)
        self.smtp_server = value

    @property
    def __line(self):
        warn("Access to __line attribute on SMTPChannel is deprecated, "
            "use 'received_lines' instead", DeprecationWarning, 2)
        return self.received_lines
    @__line.setter
    def __line(self, value):
        warn("Setting __line attribute on SMTPChannel is deprecated, "
            "set 'received_lines' instead", DeprecationWarning, 2)
        self.received_lines = value

    @property
    def __state(self):
        warn("Access to __state attribute on SMTPChannel is deprecated, "
            "use 'smtp_state' instead", DeprecationWarning, 2)
        return self.smtp_state
    @__state.setter
    def __state(self, value):
        warn("Setting __state attribute on SMTPChannel is deprecated, "
            "set 'smtp_state' instead", DeprecationWarning, 2)
        self.smtp_state = value

    @property
    def __greeting(self):
        warn("Access to __greeting attribute on SMTPChannel is deprecated, "
            "use 'seen_greeting' instead", DeprecationWarning, 2)
        return self.seen_greeting
    @__greeting.setter
    def __greeting(self, value):
        warn("Setting __greeting attribute on SMTPChannel is deprecated, "
            "set 'seen_greeting' instead", DeprecationWarning, 2)
        self.seen_greeting = value

    @property
    def __mailfrom(self):
        warn("Access to __mailfrom attribute on SMTPChannel is deprecated, "
            "use 'mailfrom' instead", DeprecationWarning, 2)
        return self.mailfrom
    @__mailfrom.setter
    def __mailfrom(self, value):
        warn("Setting __mailfrom attribute on SMTPChannel is deprecated, "
            "set 'mailfrom' instead", DeprecationWarning, 2)
        self.mailfrom = value

    @property
    def __rcpttos(self):
        warn("Access to __rcpttos attribute on SMTPChannel is deprecated, "
            "use 'rcpttos' instead", DeprecationWarning, 2)
        return self.rcpttos
    @__rcpttos.setter
    def __rcpttos(self, value):
        warn("Setting __rcpttos attribute on SMTPChannel is deprecated, "
            "set 'rcpttos' instead", DeprecationWarning, 2)
        self.rcpttos = value

    @property
    def __data(self):
        warn("Access to __data attribute on SMTPChannel is deprecated, "
            "use 'received_data' instead", DeprecationWarning, 2)
        return self.received_data
    @__data.setter
    def __data(self, value):
        warn("Setting __data attribute on SMTPChannel is deprecated, "
            "set 'received_data' instead", DeprecationWarning, 2)
        self.received_data = value

    @property
    def __fqdn(self):
        warn("Access to __fqdn attribute on SMTPChannel is deprecated, "
            "use 'fqdn' instead", DeprecationWarning, 2)
        return self.fqdn
    @__fqdn.setter
    def __fqdn(self, value):
        warn("Setting __fqdn attribute on SMTPChannel is deprecated, "
            "set 'fqdn' instead", DeprecationWarning, 2)
        self.fqdn = value

    @property
    def __peer(self):
        warn("Access to __peer attribute on SMTPChannel is deprecated, "
            "use 'peer' instead", DeprecationWarning, 2)
        return self.peer
    @__peer.setter
    def __peer(self, value):
        warn("Setting __peer attribute on SMTPChannel is deprecated, "
            "set 'peer' instead", DeprecationWarning, 2)
        self.peer = value

    @property
    def __conn(self):
        warn("Access to __conn attribute on SMTPChannel is deprecated, "
            "use 'conn' instead", DeprecationWarning, 2)
        return self.conn
    @__conn.setter
    def __conn(self, value):
        warn("Setting __conn attribute on SMTPChannel is deprecated, "
            "set 'conn' instead", DeprecationWarning, 2)
        self.conn = value

    @property
    def __addr(self):
        warn("Access to __addr attribute on SMTPChannel is deprecated, "
            "use 'addr' instead", DeprecationWarning, 2)
        return self.addr
    @__addr.setter
    def __addr(self, value):
        warn("Setting __addr attribute on SMTPChannel is deprecated, "
            "set 'addr' instead", DeprecationWarning, 2)
        self.addr = value

    
    def push(self, msg):
        asynchat.async_chat.push(self, bytes(
            msg + '\r\n', 'utf-8' if self.require_SMTPUTF8 else 'ascii'))

    
    def collect_incoming_data(self, data):
        limit = None
        if self.smtp_state == self.COMMAND:
            limit = self.max_command_size_limit
        elif self.smtp_state == self.DATA:
            limit = self.data_size_limit
        if limit and self.num_bytes > limit:
            return
        elif limit:
            self.num_bytes += len(data)
        if self._decode_data:
            self.received_lines.append(str(data, 'utf-8'))
        else:
            self.received_lines.append(data)

    
    def found_terminator(self):
        line = self._emptystring.join(self.received_lines)
        print('Data:', repr(line), file=DEBUGSTREAM)
        self.received_lines = []
        if self.smtp_state == self.COMMAND:
            sz, self.num_bytes = self.num_bytes, 0
            if not line:
                self.push('500 Error: bad syntax')
                return
            if not self._decode_data:
                line = str(line, 'utf-8')
            i = line.find(' ')
            if i < 0:
                command = line.upper()
                arg = None
            else:
                command = line[:i].upper()
                arg = line[i+1:].strip()
            max_sz = (self.command_size_limits[command]
                        if self.extended_smtp else self.command_size_limit)
            if sz > max_sz:
                self.push('500 Error: line too long')
                return
            method = getattr(self, 'smtp_' + command, None)
            if not method:
                self.push('500 Error: command "%s" not recognized' % command)
                return
            method(arg)
            return
        else:
            if self.smtp_state != self.DATA:
                self.push('451 Internal confusion')
                self.num_bytes = 0
                return
            if self.data_size_limit and self.num_bytes > self.data_size_limit:
                self.push('552 Error: Too much mail data')
                self.num_bytes = 0
                return
            
            
            data = []
            for text in line.split(self._linesep):
                if text and text[0] == self._dotsep:
                    data.append(text[1:])
                else:
                    data.append(text)
            self.received_data = self._newline.join(data)
            args = (self.peer, self.mailfrom, self.rcpttos, self.received_data)
            kwargs = {}
            if not self._decode_data:
                kwargs = {
                    'mail_options': self.mail_options,
                    'rcpt_options': self.rcpt_options,
                }
            status = self.smtp_server.process_message(*args, **kwargs)
            self._set_post_data_state()
            if not status:
                self.push('250 OK')
            else:
                self.push(status)

    
    def smtp_HELO(self, arg):
        if not arg:
            self.push('501 Syntax: HELO hostname')
            return
        
        if self.seen_greeting:
            self.push('503 Duplicate HELO/EHLO')
            return
        self._set_rset_state()
        self.seen_greeting = arg
        self.push('250 %s' % self.fqdn)

    def smtp_EHLO(self, arg):
        if not arg:
            self.push('501 Syntax: EHLO hostname')
            return
        
        if self.seen_greeting:
            self.push('503 Duplicate HELO/EHLO')
            return
        self._set_rset_state()
        self.seen_greeting = arg
        self.extended_smtp = True
        self.push('250-%s' % self.fqdn)
        if self.data_size_limit:
            self.push('250-SIZE %s' % self.data_size_limit)
            self.command_size_limits['MAIL'] += 26
        if not self._decode_data:
            self.push('250-8BITMIME')
        if self.enable_SMTPUTF8:
            self.push('250-SMTPUTF8')
            self.command_size_limits['MAIL'] += 10
        self.push('250 HELP')

    def smtp_NOOP(self, arg):
        if arg:
            self.push('501 Syntax: NOOP')
        else:
            self.push('250 OK')

    def smtp_QUIT(self, arg):
        
        self.push('221 Bye')
        self.close_when_done()

    def _strip_command_keyword(self, keyword, arg):
        keylen = len(keyword)
        if arg[:keylen].upper() == keyword:
            return arg[keylen:].strip()
        return ''

    def _getaddr(self, arg):
        if not arg:
            return '', ''
        if arg.lstrip().startswith('<'):
            address, rest = get_angle_addr(arg)
        else:
            address, rest = get_addr_spec(arg)
        if not address:
            return address, rest
        return address.addr_spec, rest

    def _getparams(self, params):
        
        
        result = {}
        for param in params:
            param, eq, value = param.partition('=')
            if not param.isalnum() or eq and not value:
                return None
            result[param] = value if eq else True
        return result

    def smtp_HELP(self, arg):
        if arg:
            extended = ' [SP <mail-parameters>]'
            lc_arg = arg.upper()
            if lc_arg == 'EHLO':
                self.push('250 Syntax: EHLO hostname')
            elif lc_arg == 'HELO':
                self.push('250 Syntax: HELO hostname')
            elif lc_arg == 'MAIL':
                msg = '250 Syntax: MAIL FROM: <address>'
                if self.extended_smtp:
                    msg += extended
                self.push(msg)
            elif lc_arg == 'RCPT':
                msg = '250 Syntax: RCPT TO: <address>'
                if self.extended_smtp:
                    msg += extended
                self.push(msg)
            elif lc_arg == 'DATA':
                self.push('250 Syntax: DATA')
            elif lc_arg == 'RSET':
                self.push('250 Syntax: RSET')
            elif lc_arg == 'NOOP':
                self.push('250 Syntax: NOOP')
            elif lc_arg == 'QUIT':
                self.push('250 Syntax: QUIT')
            elif lc_arg == 'VRFY':
                self.push('250 Syntax: VRFY <address>')
            else:
                self.push('501 Supported commands: EHLO HELO MAIL RCPT '
                          'DATA RSET NOOP QUIT VRFY')
        else:
            self.push('250 Supported commands: EHLO HELO MAIL RCPT DATA '
                      'RSET NOOP QUIT VRFY')

    def smtp_VRFY(self, arg):
        if arg:
            address, params = self._getaddr(arg)
            if address:
                self.push('252 Cannot VRFY user, but will accept message '
                          'and attempt delivery')
            else:
                self.push('502 Could not VRFY %s' % arg)
        else:
            self.push('501 Syntax: VRFY <address>')

    def smtp_MAIL(self, arg):
        if not self.seen_greeting:
            self.push('503 Error: send HELO first')
            return
        print('===> MAIL', arg, file=DEBUGSTREAM)
        syntaxerr = '501 Syntax: MAIL FROM: <address>'
        if self.extended_smtp:
            syntaxerr += ' [SP <mail-parameters>]'
        if arg is None:
            self.push(syntaxerr)
            return
        arg = self._strip_command_keyword('FROM:', arg)
        address, params = self._getaddr(arg)
        if not address:
            self.push(syntaxerr)
            return
        if not self.extended_smtp and params:
            self.push(syntaxerr)
            return
        if self.mailfrom:
            self.push('503 Error: nested MAIL command')
            return
        self.mail_options = params.upper().split()
        params = self._getparams(self.mail_options)
        if params is None:
            self.push(syntaxerr)
            return
        if not self._decode_data:
            body = params.pop('BODY', '7BIT')
            if body not in ['7BIT', '8BITMIME']:
                self.push('501 Error: BODY can only be one of 7BIT, 8BITMIME')
                return
        if self.enable_SMTPUTF8:
            smtputf8 = params.pop('SMTPUTF8', False)
            if smtputf8 is True:
                self.require_SMTPUTF8 = True
            elif smtputf8 is not False:
                self.push('501 Error: SMTPUTF8 takes no arguments')
                return
        size = params.pop('SIZE', None)
        if size:
            if not size.isdigit():
                self.push(syntaxerr)
                return
            elif self.data_size_limit and int(size) > self.data_size_limit:
                self.push('552 Error: message size exceeds fixed maximum message size')
                return
        if len(params.keys()) > 0:
            self.push('555 MAIL FROM parameters not recognized or not implemented')
            return
        self.mailfrom = address
        print('sender:', self.mailfrom, file=DEBUGSTREAM)
        self.push('250 OK')

    def smtp_RCPT(self, arg):
        if not self.seen_greeting:
            self.push('503 Error: send HELO first');
            return
        print('===> RCPT', arg, file=DEBUGSTREAM)
        if not self.mailfrom:
            self.push('503 Error: need MAIL command')
            return
        syntaxerr = '501 Syntax: RCPT TO: <address>'
        if self.extended_smtp:
            syntaxerr += ' [SP <mail-parameters>]'
        if arg is None:
            self.push(syntaxerr)
            return
        arg = self._strip_command_keyword('TO:', arg)
        address, params = self._getaddr(arg)
        if not address:
            self.push(syntaxerr)
            return
        if not self.extended_smtp and params:
            self.push(syntaxerr)
            return
        self.rcpt_options = params.upper().split()
        params = self._getparams(self.rcpt_options)
        if params is None:
            self.push(syntaxerr)
            return
        
        if len(params.keys()) > 0:
            self.push('555 RCPT TO parameters not recognized or not implemented')
            return
        self.rcpttos.append(address)
        print('recips:', self.rcpttos, file=DEBUGSTREAM)
        self.push('250 OK')

    def smtp_RSET(self, arg):
        if arg:
            self.push('501 Syntax: RSET')
            return
        self._set_rset_state()
        self.push('250 OK')

    def smtp_DATA(self, arg):
        if not self.seen_greeting:
            self.push('503 Error: send HELO first');
            return
        if not self.rcpttos:
            self.push('503 Error: need RCPT command')
            return
        if arg:
            self.push('501 Syntax: DATA')
            return
        self.smtp_state = self.DATA
        self.set_terminator(b'\r\n.\r\n')
        self.push('354 End data with <CR><LF>.<CR><LF>')

    
    def smtp_EXPN(self, arg):
        self.push('502 EXPN not implemented')


class SMTPServer(asyncore.dispatcher):
    
    channel_class = SMTPChannel

    def __init__(self, localaddr, remoteaddr,
                 data_size_limit=DATA_SIZE_DEFAULT, map=None,
                 enable_SMTPUTF8=False, decode_data=False):
        self._localaddr = localaddr
        self._remoteaddr = remoteaddr
        self.data_size_limit = data_size_limit
        self.enable_SMTPUTF8 = enable_SMTPUTF8
        self._decode_data = decode_data
        if enable_SMTPUTF8 and decode_data:
            raise ValueError("decode_data and enable_SMTPUTF8 cannot"
                             " be set to True at the same time")
        asyncore.dispatcher.__init__(self, map=map)
        try:
            gai_results = socket.getaddrinfo(*localaddr,
                                             type=socket.SOCK_STREAM)
            self.create_socket(gai_results[0][0], gai_results[0][1])
            
            self.set_reuse_addr()
            self.bind(localaddr)
            self.listen(5)
        except:
            self.close()
            raise
        else:
            print('%s started at %s\n\tLocal addr: %s\n\tRemote addr:%s' % (
                self.__class__.__name__, time.ctime(time.time()),
                localaddr, remoteaddr), file=DEBUGSTREAM)

    def handle_accepted(self, conn, addr):
        print('Incoming connection from %s' % repr(addr), file=DEBUGSTREAM)
        channel = self.channel_class(self,
                                     conn,
                                     addr,
                                     self.data_size_limit,
                                     self._map,
                                     self.enable_SMTPUTF8,
                                     self._decode_data)

    
    def process_message(self, peer, mailfrom, rcpttos, data, **kwargs):
        
        raise NotImplementedError


class DebuggingServer(SMTPServer):

    def _print_message_content(self, peer, data):
        inheaders = 1
        lines = data.splitlines()
        for line in lines:
            
            if inheaders and not line:
                peerheader = 'X-Peer: ' + peer[0]
                if not isinstance(data, str):
                    
                    peerheader = repr(peerheader.encode('utf-8'))
                print(peerheader)
                inheaders = 0
            if not isinstance(data, str):
                
                line = repr(line)
            print(line)

    def process_message(self, peer, mailfrom, rcpttos, data, **kwargs):
        print('---------- MESSAGE FOLLOWS ----------')
        if kwargs:
            if kwargs.get('mail_options'):
                print('mail options: %s' % kwargs['mail_options'])
            if kwargs.get('rcpt_options'):
                print('rcpt options: %s\n' % kwargs['rcpt_options'])
        self._print_message_content(peer, data)
        print('------------ END MESSAGE ------------')


class PureProxy(SMTPServer):
    def __init__(self, *args, **kwargs):
        if 'enable_SMTPUTF8' in kwargs and kwargs['enable_SMTPUTF8']:
            raise ValueError("PureProxy does not support SMTPUTF8.")
        super(PureProxy, self).__init__(*args, **kwargs)

    def process_message(self, peer, mailfrom, rcpttos, data):
        lines = data.split('\n')
        
        i = 0
        for line in lines:
            if not line:
                break
            i += 1
        lines.insert(i, 'X-Peer: %s' % peer[0])
        data = NEWLINE.join(lines)
        refused = self._deliver(mailfrom, rcpttos, data)
        
        print('we got some refusals:', refused, file=DEBUGSTREAM)

    def _deliver(self, mailfrom, rcpttos, data):
        import smtplib
        refused = {}
        try:
            s = smtplib.SMTP()
            s.connect(self._remoteaddr[0], self._remoteaddr[1])
            try:
                refused = s.sendmail(mailfrom, rcpttos, data)
            finally:
                s.quit()
        except smtplib.SMTPRecipientsRefused as e:
            print('got SMTPRecipientsRefused', file=DEBUGSTREAM)
            refused = e.recipients
        except (OSError, smtplib.SMTPException) as e:
            print('got', e.__class__, file=DEBUGSTREAM)
            
            
            
            errcode = getattr(e, 'smtp_code', -1)
            errmsg = getattr(e, 'smtp_error', 'ignore')
            for r in rcpttos:
                refused[r] = (errcode, errmsg)
        return refused


class Options:
    setuid = True
    classname = 'PureProxy'
    size_limit = None
    enable_SMTPUTF8 = False


def parseargs():
    global DEBUGSTREAM
    try:
        opts, args = getopt.getopt(
            sys.argv[1:], 'nVhc:s:du',
            ['class=', 'nosetuid', 'version', 'help', 'size=', 'debug',
             'smtputf8'])
    except getopt.error as e:
        usage(1, e)

    options = Options()
    for opt, arg in opts:
        if opt in ('-h', '--help'):
            usage(0)
        elif opt in ('-V', '--version'):
            print(__version__)
            sys.exit(0)
        elif opt in ('-n', '--nosetuid'):
            options.setuid = False
        elif opt in ('-c', '--class'):
            options.classname = arg
        elif opt in ('-d', '--debug'):
            DEBUGSTREAM = sys.stderr
        elif opt in ('-u', '--smtputf8'):
            options.enable_SMTPUTF8 = True
        elif opt in ('-s', '--size'):
            try:
                int_size = int(arg)
                options.size_limit = int_size
            except:
                print('Invalid size: ' + arg, file=sys.stderr)
                sys.exit(1)

    
    if len(args) < 1:
        localspec = 'localhost:8025'
        remotespec = 'localhost:25'
    elif len(args) < 2:
        localspec = args[0]
        remotespec = 'localhost:25'
    elif len(args) < 3:
        localspec = args[0]
        remotespec = args[1]
    else:
        usage(1, 'Invalid arguments: %s' % COMMASPACE.join(args))

    
    i = localspec.find(':')
    if i < 0:
        usage(1, 'Bad local spec: %s' % localspec)
    options.localhost = localspec[:i]
    try:
        options.localport = int(localspec[i+1:])
    except ValueError:
        usage(1, 'Bad local port: %s' % localspec)
    i = remotespec.find(':')
    if i < 0:
        usage(1, 'Bad remote spec: %s' % remotespec)
    options.remotehost = remotespec[:i]
    try:
        options.remoteport = int(remotespec[i+1:])
    except ValueError:
        usage(1, 'Bad remote port: %s' % remotespec)
    return options


if __name__ == '__main__':
    options = parseargs()
    
    classname = options.classname
    if "." in classname:
        lastdot = classname.rfind(".")
        mod = __import__(classname[:lastdot], globals(), locals(), [""])
        classname = classname[lastdot+1:]
    else:
        import __main__ as mod
    class_ = getattr(mod, classname)
    proxy = class_((options.localhost, options.localport),
                   (options.remotehost, options.remoteport),
                   options.size_limit, enable_SMTPUTF8=options.enable_SMTPUTF8)
    if options.setuid:
        try:
            import pwd
        except ImportError:
            print('Cannot import module "pwd"; try running with -n option.', file=sys.stderr)
            sys.exit(1)
        nobody = pwd.getpwnam('nobody')[2]
        try:
            os.setuid(nobody)
        except PermissionError:
            print('Cannot setuid "nobody"; try running with -n option.', file=sys.stderr)
            sys.exit(1)
    try:
        asyncore.loop()
    except KeyboardInterrupt:
        pass