2 """An RFC 2821 smtp proxy.
4 Usage: %(program)s [options] [localhost:localport [remotehost:remoteport]]
10 This program generally tries to setuid `nobody', unless this flag is
11 set. The setuid call will fail if this program is not run as root (in
12 which case, use this flag).
16 Print the version number and exit.
20 Use `classname' as the concrete SMTP proxy class. Uses `PureProxy' by
25 Turn on debugging prints.
29 Print this message and exit.
31 Version: %(__version__)s
33 If localhost is not given then `localhost' is used, and if localport is not
34 given then 8025 is used. If remotehost is not given then `localhost' is used,
35 and if remoteport is not given, then 25 is used.
41 # This file implements the minimal SMTP protocol as defined in RFC 821. It
42 # has a hierarchy of classes which implement the backend functionality for the
43 # smtpd. A number of classes are provided:
45 # SMTPServer - the base class for the backend. Raises NotImplementedError
46 # if you try to use it.
48 # DebuggingServer - simply prints each message it receives on stdout.
50 # PureProxy - Proxies all messages to a real smtpd which does final
51 # delivery. One known problem with this class is that it doesn't handle
52 # SMTP errors from the backend server at all. This should be fixed
53 # (contributions are welcome!).
55 # MailmanProxy - An experimental hack to work with GNU Mailman
56 # <www.list.org>. Using this server as your real incoming smtpd, your
57 # mailhost will automatically recognize and accept mail destined to Mailman
58 # lists when those lists are created. Every message not destined for a list
59 # gets forwarded to a real backend smtpd, as with PureProxy. Again, errors
60 # are not handled correctly yet.
62 # Please note that this script requires Python 2.0
64 # Author: Barry Warsaw <barry@python.org>
68 # - support mailbox delivery
71 # - handle error codes from the backend smtpd
82 __all__
= ["SMTPServer","DebuggingServer","PureProxy","MailmanProxy"]
85 __version__
= 'Python SMTP proxy version 0.2'
89 def write(self
, msg
): pass
93 DEBUGSTREAM
= Devnull()
100 def usage(code
, msg
=''):
101 print(__doc__
% globals(), file=sys
.stderr
)
103 print(msg
, file=sys
.stderr
)
108 class SMTPChannel(asynchat
.async_chat
):
112 def __init__(self
, server
, conn
, addr
):
113 asynchat
.async_chat
.__init
__(self
, conn
)
114 self
.__server
= server
118 self
.__state
= self
.COMMAND
120 self
.__mailfrom
= None
123 self
.__fqdn
= socket
.getfqdn()
124 self
.__peer
= conn
.getpeername()
125 print('Peer:', repr(self
.__peer
), file=DEBUGSTREAM
)
126 self
.push('220 %s %s' % (self
.__fqdn
, __version__
))
127 self
.set_terminator(b
'\r\n')
129 # Overrides base class for convenience
131 asynchat
.async_chat
.push(self
, bytes(msg
+ '\r\n', 'ascii'))
133 # Implementation of base class abstract method
134 def collect_incoming_data(self
, data
):
135 self
.__line
.append(str(data
, "utf8"))
137 # Implementation of base class abstract method
138 def found_terminator(self
):
139 line
= EMPTYSTRING
.join(self
.__line
)
140 print('Data:', repr(line
), file=DEBUGSTREAM
)
142 if self
.__state
== self
.COMMAND
:
144 self
.push('500 Error: bad syntax')
149 command
= line
.upper()
152 command
= line
[:i
].upper()
153 arg
= line
[i
+1:].strip()
154 method
= getattr(self
, 'smtp_' + command
, None)
156 self
.push('502 Error: command "%s" not implemented' % command
)
161 if self
.__state
!= self
.DATA
:
162 self
.push('451 Internal confusion')
164 # Remove extraneous carriage returns and de-transparency according
165 # to RFC 821, Section 4.5.2.
167 for text
in line
.split('\r\n'):
168 if text
and text
[0] == '.':
169 data
.append(text
[1:])
172 self
.__data
= NEWLINE
.join(data
)
173 status
= self
.__server
.process_message(self
.__peer
,
178 self
.__mailfrom
= None
179 self
.__state
= self
.COMMAND
180 self
.set_terminator(b
'\r\n')
186 # SMTP and ESMTP commands
187 def smtp_HELO(self
, arg
):
189 self
.push('501 Syntax: HELO hostname')
192 self
.push('503 Duplicate HELO/EHLO')
194 self
.__greeting
= arg
195 self
.push('250 %s' % self
.__fqdn
)
197 def smtp_NOOP(self
, arg
):
199 self
.push('501 Syntax: NOOP')
203 def smtp_QUIT(self
, arg
):
206 self
.close_when_done()
209 def __getaddr(self
, keyword
, arg
):
211 keylen
= len(keyword
)
212 if arg
[:keylen
].upper() == keyword
:
213 address
= arg
[keylen
:].strip()
216 elif address
[0] == '<' and address
[-1] == '>' and address
!= '<>':
217 # Addresses can be in the form <person@dom.com> but watch out
218 # for null address, e.g. <>
219 address
= address
[1:-1]
222 def smtp_MAIL(self
, arg
):
223 print('===> MAIL', arg
, file=DEBUGSTREAM
)
224 address
= self
.__getaddr
('FROM:', arg
) if arg
else None
226 self
.push('501 Syntax: MAIL FROM:<address>')
229 self
.push('503 Error: nested MAIL command')
231 self
.__mailfrom
= address
232 print('sender:', self
.__mailfrom
, file=DEBUGSTREAM
)
235 def smtp_RCPT(self
, arg
):
236 print('===> RCPT', arg
, file=DEBUGSTREAM
)
237 if not self
.__mailfrom
:
238 self
.push('503 Error: need MAIL command')
240 address
= self
.__getaddr
('TO:', arg
) if arg
else None
242 self
.push('501 Syntax: RCPT TO: <address>')
244 self
.__rcpttos
.append(address
)
245 print('recips:', self
.__rcpttos
, file=DEBUGSTREAM
)
248 def smtp_RSET(self
, arg
):
250 self
.push('501 Syntax: RSET')
252 # Resets the sender, recipients, and data, but not the greeting
253 self
.__mailfrom
= None
256 self
.__state
= self
.COMMAND
259 def smtp_DATA(self
, arg
):
260 if not self
.__rcpttos
:
261 self
.push('503 Error: need RCPT command')
264 self
.push('501 Syntax: DATA')
266 self
.__state
= self
.DATA
267 self
.set_terminator(b
'\r\n.\r\n')
268 self
.push('354 End data with <CR><LF>.<CR><LF>')
272 class SMTPServer(asyncore
.dispatcher
):
273 def __init__(self
, localaddr
, remoteaddr
):
274 self
._localaddr
= localaddr
275 self
._remoteaddr
= remoteaddr
276 asyncore
.dispatcher
.__init
__(self
)
277 self
.create_socket(socket
.AF_INET
, socket
.SOCK_STREAM
)
278 # try to re-use a server port if possible
279 self
.set_reuse_addr()
282 print('%s started at %s\n\tLocal addr: %s\n\tRemote addr:%s' % (
283 self
.__class
__.__name
__, time
.ctime(time
.time()),
284 localaddr
, remoteaddr
), file=DEBUGSTREAM
)
286 def handle_accept(self
):
287 conn
, addr
= self
.accept()
288 print('Incoming connection from %s' % repr(addr
), file=DEBUGSTREAM
)
289 channel
= SMTPChannel(self
, conn
, addr
)
291 # API for "doing something useful with the message"
292 def process_message(self
, peer
, mailfrom
, rcpttos
, data
):
293 """Override this abstract method to handle messages from the client.
295 peer is a tuple containing (ipaddr, port) of the client that made the
296 socket connection to our smtp port.
298 mailfrom is the raw address the client claims the message is coming
301 rcpttos is a list of raw addresses the client wishes to deliver the
304 data is a string containing the entire full text of the message,
305 headers (if supplied) and all. It has been `de-transparencied'
306 according to RFC 821, Section 4.5.2. In other words, a line
307 containing a `.' followed by other text has had the leading dot
310 This function should return None, for a normal `250 Ok' response;
311 otherwise it returns the desired response string in RFC 821 format.
314 raise NotImplementedError
318 class DebuggingServer(SMTPServer
):
319 # Do something with the gathered message
320 def process_message(self
, peer
, mailfrom
, rcpttos
, data
):
322 lines
= data
.split('\n')
323 print('---------- MESSAGE FOLLOWS ----------')
326 if inheaders
and not line
:
327 print('X-Peer:', peer
[0])
330 print('------------ END MESSAGE ------------')
334 class PureProxy(SMTPServer
):
335 def process_message(self
, peer
, mailfrom
, rcpttos
, data
):
336 lines
= data
.split('\n')
337 # Look for the last header
343 lines
.insert(i
, 'X-Peer: %s' % peer
[0])
344 data
= NEWLINE
.join(lines
)
345 refused
= self
._deliver
(mailfrom
, rcpttos
, data
)
346 # TBD: what to do with refused addresses?
347 print('we got some refusals:', refused
, file=DEBUGSTREAM
)
349 def _deliver(self
, mailfrom
, rcpttos
, data
):
354 s
.connect(self
._remoteaddr
[0], self
._remoteaddr
[1])
356 refused
= s
.sendmail(mailfrom
, rcpttos
, data
)
359 except smtplib
.SMTPRecipientsRefused
as e
:
360 print('got SMTPRecipientsRefused', file=DEBUGSTREAM
)
361 refused
= e
.recipients
362 except (socket
.error
, smtplib
.SMTPException
) as e
:
363 print('got', e
.__class
__, file=DEBUGSTREAM
)
364 # All recipients were refused. If the exception had an associated
365 # error code, use it. Otherwise,fake it with a non-triggering
367 errcode
= getattr(e
, 'smtp_code', -1)
368 errmsg
= getattr(e
, 'smtp_error', 'ignore')
370 refused
[r
] = (errcode
, errmsg
)
375 class MailmanProxy(PureProxy
):
376 def process_message(self
, peer
, mailfrom
, rcpttos
, data
):
377 from io
import StringIO
378 from Mailman
import Utils
379 from Mailman
import Message
380 from Mailman
import MailList
381 # If the message is to a Mailman mailing list, then we'll invoke the
382 # Mailman script directly, without going through the real smtpd.
383 # Otherwise we'll forward it to the local proxy for disposition.
386 local
= rcpt
.lower().split('@')[0]
387 # We allow the following variations on the theme
394 parts
= local
.split('-')
402 if not Utils
.list_exists(listname
) or command
not in (
403 '', 'admin', 'owner', 'request', 'join', 'leave'):
405 listnames
.append((rcpt
, listname
, command
))
406 # Remove all list recipients from rcpttos and forward what we're not
407 # going to take care of ourselves. Linear removal should be fine
408 # since we don't expect a large number of recipients.
409 for rcpt
, listname
, command
in listnames
:
411 # If there's any non-list destined recipients left,
412 print('forwarding recips:', ' '.join(rcpttos
), file=DEBUGSTREAM
)
414 refused
= self
._deliver
(mailfrom
, rcpttos
, data
)
415 # TBD: what to do with refused addresses?
416 print('we got refusals:', refused
, file=DEBUGSTREAM
)
417 # Now deliver directly to the list commands
420 msg
= Message
.Message(s
)
421 # These headers are required for the proper execution of Mailman. All
422 # MTAs in existence seem to add these if the original message doesn't
424 if not msg
.get('from'):
425 msg
['From'] = mailfrom
426 if not msg
.get('date'):
427 msg
['Date'] = time
.ctime(time
.time())
428 for rcpt
, listname
, command
in listnames
:
429 print('sending message to', rcpt
, file=DEBUGSTREAM
)
430 mlist
= mlists
.get(listname
)
432 mlist
= MailList
.MailList(listname
, lock
=0)
433 mlists
[listname
] = mlist
434 # dispatch on the type of command
437 msg
.Enqueue(mlist
, tolist
=1)
438 elif command
== 'admin':
439 msg
.Enqueue(mlist
, toadmin
=1)
440 elif command
== 'owner':
441 msg
.Enqueue(mlist
, toowner
=1)
442 elif command
== 'request':
443 msg
.Enqueue(mlist
, torequest
=1)
444 elif command
in ('join', 'leave'):
445 # TBD: this is a hack!
446 if command
== 'join':
447 msg
['Subject'] = 'subscribe'
449 msg
['Subject'] = 'unsubscribe'
450 msg
.Enqueue(mlist
, torequest
=1)
456 classname
= 'PureProxy'
463 opts
, args
= getopt
.getopt(
464 sys
.argv
[1:], 'nVhc:d',
465 ['class=', 'nosetuid', 'version', 'help', 'debug'])
466 except getopt
.error
as e
:
470 for opt
, arg
in opts
:
471 if opt
in ('-h', '--help'):
473 elif opt
in ('-V', '--version'):
474 print(__version__
, file=sys
.stderr
)
476 elif opt
in ('-n', '--nosetuid'):
478 elif opt
in ('-c', '--class'):
479 options
.classname
= arg
480 elif opt
in ('-d', '--debug'):
481 DEBUGSTREAM
= sys
.stderr
483 # parse the rest of the arguments
485 localspec
= 'localhost:8025'
486 remotespec
= 'localhost:25'
489 remotespec
= 'localhost:25'
494 usage(1, 'Invalid arguments: %s' % COMMASPACE
.join(args
))
496 # split into host/port pairs
497 i
= localspec
.find(':')
499 usage(1, 'Bad local spec: %s' % localspec
)
500 options
.localhost
= localspec
[:i
]
502 options
.localport
= int(localspec
[i
+1:])
504 usage(1, 'Bad local port: %s' % localspec
)
505 i
= remotespec
.find(':')
507 usage(1, 'Bad remote spec: %s' % remotespec
)
508 options
.remotehost
= remotespec
[:i
]
510 options
.remoteport
= int(remotespec
[i
+1:])
512 usage(1, 'Bad remote port: %s' % remotespec
)
517 if __name__
== '__main__':
518 options
= parseargs()
524 print('Cannot import module "pwd"; try running with -n option.', file=sys
.stderr
)
526 nobody
= pwd
.getpwnam('nobody')[2]
530 if e
.errno
!= errno
.EPERM
: raise
531 print('Cannot setuid "nobody"; try running with -n option.', file=sys
.stderr
)
533 classname
= options
.classname
535 lastdot
= classname
.rfind(".")
536 mod
= __import__(classname
[:lastdot
], globals(), locals(), [""])
537 classname
= classname
[lastdot
+1:]
539 import __main__
as mod
540 class_
= getattr(mod
, classname
)
541 proxy
= class_((options
.localhost
, options
.localport
),
542 (options
.remotehost
, options
.remoteport
))
545 except KeyboardInterrupt: