diff options
Diffstat (limited to 'Lib/smtpd.py')
| -rwxr-xr-x | Lib/smtpd.py | 287 |
1 files changed, 206 insertions, 81 deletions
diff --git a/Lib/smtpd.py b/Lib/smtpd.py index db7c867..732066e 100755 --- a/Lib/smtpd.py +++ b/Lib/smtpd.py @@ -1,5 +1,5 @@ #! /usr/bin/env python3 -"""An RFC 5321 smtp proxy. +"""An RFC 5321 smtp proxy with optional RFC 1870 and RFC 6531 extensions. Usage: %(program)s [options] [localhost:localport [remotehost:remoteport]] @@ -25,6 +25,10 @@ Options: 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. @@ -98,7 +102,6 @@ class Devnull: DEBUGSTREAM = Devnull() NEWLINE = '\n' -EMPTYSTRING = '' COMMASPACE = ', ' DATA_SIZE_DEFAULT = 33554432 @@ -116,26 +119,48 @@ class SMTPChannel(asynchat.async_chat): command_size_limit = 512 command_size_limits = collections.defaultdict(lambda x=command_size_limit: x) - command_size_limits.update({ - 'MAIL': command_size_limit + 26, - }) - max_command_size_limit = max(command_size_limits.values()) + + @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): + map=None, enable_SMTPUTF8=False, decode_data=None): 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.received_lines = [] - self.smtp_state = self.COMMAND + self.enable_SMTPUTF8 = enable_SMTPUTF8 + if enable_SMTPUTF8: + if decode_data: + raise ValueError("decode_data and enable_SMTPUTF8 cannot" + " be set to True at the same time") + decode_data = False + if decode_data is None: + warn("The decode_data default of True will change to False in 3.6;" + " specify an explicit value for this keyword", + DeprecationWarning, 2) + decode_data = True + self._decode_data = decode_data + 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.mailfrom = None - self.rcpttos = [] - self.received_data = '' + self.extended_smtp = False + self.command_size_limits.clear() self.fqdn = socket.getfqdn() - self.num_bytes = 0 try: self.peer = conn.getpeername() except OSError as err: @@ -147,8 +172,22 @@ class SMTPChannel(asynchat.async_chat): return print('Peer:', repr(self.peer), file=DEBUGSTREAM) self.push('220 %s %s' % (self.fqdn, __version__)) + + def _set_post_data_state(self): + """Reset state variables to their post-DATA state.""" + self.smtp_state = self.COMMAND + self.mailfrom = None + self.rcpttos = [] + self.require_SMTPUTF8 = False + self.num_bytes = 0 self.set_terminator(b'\r\n') - self.extended_smtp = False + + def _set_rset_state(self): + """Reset all state variables except the greeting.""" + self._set_post_data_state() + self.received_data = '' + self.received_lines = [] + # properties for backwards-compatibility @property @@ -272,9 +311,10 @@ class SMTPChannel(asynchat.async_chat): "set 'addr' instead", DeprecationWarning, 2) self.addr = value - # Overrides base class for convenience + # Overrides base class for convenience. def push(self, msg): - asynchat.async_chat.push(self, bytes(msg + '\r\n', 'ascii')) + asynchat.async_chat.push(self, bytes( + msg + '\r\n', 'utf-8' if self.require_SMTPUTF8 else 'ascii')) # Implementation of base class abstract method def collect_incoming_data(self, data): @@ -287,11 +327,14 @@ class SMTPChannel(asynchat.async_chat): return elif limit: self.num_bytes += len(data) - self.received_lines.append(str(data, "utf-8")) + if self._decode_data: + self.received_lines.append(str(data, 'utf-8')) + else: + self.received_lines.append(data) # Implementation of base class abstract method def found_terminator(self): - line = EMPTYSTRING.join(self.received_lines) + line = self._emptystring.join(self.received_lines) print('Data:', repr(line), file=DEBUGSTREAM) self.received_lines = [] if self.smtp_state == self.COMMAND: @@ -299,7 +342,8 @@ class SMTPChannel(asynchat.async_chat): if not line: self.push('500 Error: bad syntax') return - method = None + if not self._decode_data: + line = str(line, 'utf-8') i = line.find(' ') if i < 0: command = line.upper() @@ -330,21 +374,21 @@ class SMTPChannel(asynchat.async_chat): # Remove extraneous carriage returns and de-transparency according # to RFC 5321, Section 4.5.2. data = [] - for text in line.split('\r\n'): - if text and text[0] == '.': + 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 = NEWLINE.join(data) - status = self.smtp_server.process_message(self.peer, - self.mailfrom, - self.rcpttos, - self.received_data) - self.rcpttos = [] - self.mailfrom = None - self.smtp_state = self.COMMAND - self.num_bytes = 0 - self.set_terminator(b'\r\n') + 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: @@ -355,26 +399,35 @@ class SMTPChannel(asynchat.async_chat): if not arg: self.push('501 Syntax: HELO hostname') return + # See issue #21783 for a discussion of this behavior. if self.seen_greeting: self.push('503 Duplicate HELO/EHLO') - else: - self.seen_greeting = arg - self.extended_smtp = False - self.push('250 %s' % self.fqdn) + 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 + # See issue #21783 for a discussion of this behavior. if self.seen_greeting: self.push('503 Duplicate HELO/EHLO') - else: - 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.push('250 HELP') + 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: @@ -405,11 +458,15 @@ class SMTPChannel(asynchat.async_chat): return address.addr_spec, rest def _getparams(self, params): - # Return any parameters that appear to be syntactically valid according - # to RFC 1869, ignore all others. (Postel rule: accept what we can.) - params = [param.split('=', 1) for param in params.split() - if '=' in param] - return {k: v for k, v in params if k.isalnum()} + # Return params as dictionary. Return None if not all parameters + # appear to be syntactically valid according to RFC 1869. + 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: @@ -459,7 +516,7 @@ class SMTPChannel(asynchat.async_chat): def smtp_MAIL(self, arg): if not self.seen_greeting: - self.push('503 Error: send HELO first'); + self.push('503 Error: send HELO first') return print('===> MAIL', arg, file=DEBUGSTREAM) syntaxerr = '501 Syntax: MAIL FROM: <address>' @@ -479,10 +536,23 @@ class SMTPChannel(asynchat.async_chat): if self.mailfrom: self.push('503 Error: nested MAIL command') return - params = self._getparams(params.upper()) + 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(): @@ -517,16 +587,16 @@ class SMTPChannel(asynchat.async_chat): if not address: self.push(syntaxerr) return - if params: - if self.extended_smtp: - params = self._getparams(params.upper()) - if params is None: - self.push(syntaxerr) - return - else: - self.push(syntaxerr) - return - if params and len(params.keys()) > 0: + 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 + # XXX currently there are no options we recognize. + if len(params.keys()) > 0: self.push('555 RCPT TO parameters not recognized or not implemented') return self.rcpttos.append(address) @@ -537,11 +607,7 @@ class SMTPChannel(asynchat.async_chat): if arg: self.push('501 Syntax: RSET') return - # Resets the sender, recipients, and data, but not the greeting - self.mailfrom = None - self.rcpttos = [] - self.received_data = '' - self.smtp_state = self.COMMAND + self._set_rset_state() self.push('250 OK') def smtp_DATA(self, arg): @@ -568,13 +634,29 @@ class SMTPServer(asyncore.dispatcher): channel_class = SMTPChannel def __init__(self, localaddr, remoteaddr, - data_size_limit=DATA_SIZE_DEFAULT, map=None): + data_size_limit=DATA_SIZE_DEFAULT, map=None, + enable_SMTPUTF8=False, decode_data=None): self._localaddr = localaddr self._remoteaddr = remoteaddr self.data_size_limit = data_size_limit + self.enable_SMTPUTF8 = enable_SMTPUTF8 + if enable_SMTPUTF8: + if decode_data: + raise ValueError("The decode_data and enable_SMTPUTF8" + " parameters cannot be set to True at the" + " same time.") + decode_data = False + if decode_data is None: + warn("The decode_data default of True will change to False in 3.6;" + " specify an explicit value for this keyword", + DeprecationWarning, 2) + decode_data = True + self._decode_data = decode_data asyncore.dispatcher.__init__(self, map=map) try: - self.create_socket(socket.AF_INET, socket.SOCK_STREAM) + gai_results = socket.getaddrinfo(*localaddr, + type=socket.SOCK_STREAM) + self.create_socket(gai_results[0][0], gai_results[0][1]) # try to re-use a server port if possible self.set_reuse_addr() self.bind(localaddr) @@ -589,11 +671,16 @@ class SMTPServer(asyncore.dispatcher): 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) + channel = self.channel_class(self, + conn, + addr, + self.data_size_limit, + self._map, + self.enable_SMTPUTF8, + self._decode_data) # API for "doing something useful with the message" - def process_message(self, peer, mailfrom, rcpttos, data): + def process_message(self, peer, mailfrom, rcpttos, data, **kwargs): """Override this abstract method to handle messages from the client. peer is a tuple containing (ipaddr, port) of the client that made the @@ -611,29 +698,58 @@ class SMTPServer(asyncore.dispatcher): containing a `.' followed by other text has had the leading dot removed. - This function should return None, for a normal `250 Ok' response; - otherwise it returns the desired response string in RFC 821 format. + kwargs is a dictionary containing additional information. It is empty + unless decode_data=False or enable_SMTPUTF8=True was given as init + parameter, in which case ut 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. """ raise NotImplementedError class DebuggingServer(SMTPServer): - # Do something with the gathered message - def process_message(self, peer, mailfrom, rcpttos, data): + + def _print_message_content(self, peer, data): inheaders = 1 - lines = data.split('\n') - print('---------- MESSAGE FOLLOWS ----------') + lines = data.splitlines() for line in lines: # headers first if inheaders and not line: - print('X-Peer:', peer[0]) + peerheader = 'X-Peer: ' + peer[0] + if not isinstance(data, str): + # decoded_data=false; make header match other binary output + peerheader = repr(peerheader.encode('utf-8')) + print(peerheader) inheaders = 0 + if not isinstance(data, str): + # Avoid spurious 'str on bytes instance' warning. + 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') # Look for the last header @@ -674,6 +790,11 @@ class PureProxy(SMTPServer): class MailmanProxy(PureProxy): + def __init__(self, *args, **kwargs): + if 'enable_SMTPUTF8' in kwargs and kwargs['enable_SMTPUTF8']: + raise ValueError("MailmanProxy does not support SMTPUTF8.") + super(PureProxy, self).__init__(*args, **kwargs) + def process_message(self, peer, mailfrom, rcpttos, data): from io import StringIO from Mailman import Utils @@ -752,17 +873,19 @@ class MailmanProxy(PureProxy): class Options: - setuid = 1 + setuid = True classname = 'PureProxy' size_limit = None + enable_SMTPUTF8 = False def parseargs(): global DEBUGSTREAM try: opts, args = getopt.getopt( - sys.argv[1:], 'nVhc:s:d', - ['class=', 'nosetuid', 'version', 'help', 'size=', 'debug']) + sys.argv[1:], 'nVhc:s:du', + ['class=', 'nosetuid', 'version', 'help', 'size=', 'debug', + 'smtputf8']) except getopt.error as e: usage(1, e) @@ -774,11 +897,13 @@ def parseargs(): print(__version__) sys.exit(0) elif opt in ('-n', '--nosetuid'): - options.setuid = 0 + 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) @@ -833,7 +958,7 @@ if __name__ == '__main__': class_ = getattr(mod, classname) proxy = class_((options.localhost, options.localport), (options.remotehost, options.remoteport), - options.size_limit) + options.size_limit, enable_SMTPUTF8=options.enable_SMTPUTF8) if options.setuid: try: import pwd |