diff options
Diffstat (limited to 'lib-python/3/smtpd.py')
| -rwxr-xr-x | lib-python/3/smtpd.py | 297 |
1 files changed, 225 insertions, 72 deletions
diff --git a/lib-python/3/smtpd.py b/lib-python/3/smtpd.py index 8cd405c5f6..778d6d6280 100755 --- a/lib-python/3/smtpd.py +++ b/lib-python/3/smtpd.py @@ -1,5 +1,5 @@ #! /usr/bin/env python3 -"""An RFC 2821 smtp proxy. +"""An RFC 5321 smtp proxy. Usage: %(program)s [options] [localhost:localport [remotehost:remoteport]] @@ -20,6 +20,11 @@ Options: 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. + --debug -d Turn on debugging prints. @@ -35,10 +40,9 @@ 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 +# 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: # @@ -66,7 +70,7 @@ and if remoteport is not given, then 25 is used. # # - support mailbox delivery # - alias files -# - ESMTP +# - Handle more ESMTP extensions # - handle error codes from the backend smtpd import sys @@ -77,12 +81,14 @@ import time import socket import asyncore import asynchat +import collections from warnings import warn +from email._header_value_parser import get_addr_spec, get_angle_addr __all__ = ["SMTPServer","DebuggingServer","PureProxy","MailmanProxy"] program = sys.argv[0] -__version__ = 'Python SMTP proxy version 0.2' +__version__ = 'Python SMTP proxy version 0.3' class Devnull: @@ -94,9 +100,9 @@ DEBUGSTREAM = Devnull() NEWLINE = '\n' EMPTYSTRING = '' COMMASPACE = ', ' +DATA_SIZE_DEFAULT = 33554432 - def usage(code, msg=''): print(__doc__ % globals(), file=sys.stderr) if msg: @@ -104,19 +110,23 @@ def usage(code, msg=''): sys.exit(code) - class SMTPChannel(asynchat.async_chat): COMMAND = 0 DATA = 1 - data_size_limit = 33554432 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()) - def __init__(self, server, conn, addr): + def __init__(self, server, conn, addr, data_size_limit=DATA_SIZE_DEFAULT): asynchat.async_chat.__init__(self, conn) 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.seen_greeting = '' @@ -137,127 +147,128 @@ class SMTPChannel(asynchat.async_chat): print('Peer:', repr(self.peer), file=DEBUGSTREAM) self.push('220 %s %s' % (self.fqdn, __version__)) self.set_terminator(b'\r\n') + self.extended_smtp = False # properties for backwards-compatibility @property def __server(self): warn("Access to __server attribute on SMTPChannel is deprecated, " - "use 'smtp_server' instead", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "set 'mailfrom' instead", DeprecationWarning, 2) self.mailfrom = value @property def __rcpttos(self): warn("Access to __rcpttos attribute on SMTPChannel is deprecated, " - "use 'rcpttos' instead", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "set 'fqdn' instead", DeprecationWarning, 2) self.fqdn = value @property def __peer(self): warn("Access to __peer attribute on SMTPChannel is deprecated, " - "use 'peer' instead", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "set 'peer' instead", DeprecationWarning, 2) self.peer = value @property def __conn(self): warn("Access to __conn attribute on SMTPChannel is deprecated, " - "use 'conn' instead", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "set 'conn' instead", DeprecationWarning, 2) self.conn = value @property def __addr(self): warn("Access to __addr attribute on SMTPChannel is deprecated, " - "use 'addr' instead", PendingDeprecationWarning, 2) + "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", PendingDeprecationWarning, 2) + "set 'addr' instead", DeprecationWarning, 2) self.addr = value # Overrides base class for convenience @@ -268,14 +279,14 @@ class SMTPChannel(asynchat.async_chat): def collect_incoming_data(self, data): limit = None if self.smtp_state == self.COMMAND: - limit = self.command_size_limit + 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) - self.received_lines.append(str(data, "utf8")) + self.received_lines.append(str(data, "utf-8")) # Implementation of base class abstract method def found_terminator(self): @@ -283,11 +294,7 @@ class SMTPChannel(asynchat.async_chat): print('Data:', repr(line), file=DEBUGSTREAM) self.received_lines = [] if self.smtp_state == self.COMMAND: - if self.num_bytes > self.command_size_limit: - self.push('500 Error: line too long') - self.num_bytes = 0 - return - self.num_bytes = 0 + sz, self.num_bytes = self.num_bytes, 0 if not line: self.push('500 Error: bad syntax') return @@ -299,9 +306,14 @@ class SMTPChannel(asynchat.async_chat): 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('502 Error: command "%s" not implemented' % command) + self.push('500 Error: command "%s" not recognized' % command) return method(arg) return @@ -310,12 +322,12 @@ class SMTPChannel(asynchat.async_chat): self.push('451 Internal confusion') self.num_bytes = 0 return - if self.num_bytes > self.data_size_limit: + 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 # Remove extraneous carriage returns and de-transparency according - # to RFC 821, Section 4.5.2. + # to RFC 5321, Section 4.5.2. data = [] for text in line.split('\r\n'): if text and text[0] == '.': @@ -333,7 +345,7 @@ class SMTPChannel(asynchat.async_chat): self.num_bytes = 0 self.set_terminator(b'\r\n') if not status: - self.push('250 Ok') + self.push('250 OK') else: self.push(status) @@ -346,58 +358,188 @@ class SMTPChannel(asynchat.async_chat): self.push('503 Duplicate HELO/EHLO') else: self.seen_greeting = arg + self.extended_smtp = False 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') + 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') + def smtp_NOOP(self, arg): if arg: self.push('501 Syntax: NOOP') else: - self.push('250 Ok') + self.push('250 OK') def smtp_QUIT(self, arg): # args is ignored self.push('221 Bye') self.close_when_done() - # factored - def __getaddr(self, keyword, arg): - address = None + def _strip_command_keyword(self, keyword, arg): keylen = len(keyword) if arg[:keylen].upper() == keyword: - address = arg[keylen:].strip() - if not address: - pass - elif address[0] == '<' and address[-1] == '>' and address != '<>': - # Addresses can be in the form <person@dom.com> but watch out - # for null address, e.g. <> - address = address[1:-1] - return address + 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): + # 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()} + + 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) - address = self.__getaddr('FROM:', arg) if arg else None + 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 not address: - self.push('501 Syntax: MAIL FROM:<address>') + self.push(syntaxerr) return if self.mailfrom: self.push('503 Error: nested MAIL command') return + params = self._getparams(params.upper()) + if params is None: + self.push(syntaxerr) + 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') + 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 - address = self.__getaddr('TO:', arg) if arg else None + 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 params: + if self.extended_smtp: + params = self._getparams(params.upper()) + if params is None: + self.push(syntaxerr) + return + else: + self.push(syntaxerr) + return + if not address: + self.push(syntaxerr) + return + if params and len(params.keys()) > 0: + self.push('555 RCPT TO parameters not recognized or not implemented') + return if not address: self.push('501 Syntax: RCPT TO: <address>') return self.rcpttos.append(address) print('recips:', self.rcpttos, file=DEBUGSTREAM) - self.push('250 Ok') + self.push('250 OK') def smtp_RSET(self, arg): if arg: @@ -408,9 +550,12 @@ class SMTPChannel(asynchat.async_chat): self.rcpttos = [] self.received_data = '' self.smtp_state = self.COMMAND - self.push('250 Ok') + 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 @@ -421,15 +566,20 @@ class SMTPChannel(asynchat.async_chat): self.set_terminator(b'\r\n.\r\n') self.push('354 End data with <CR><LF>.<CR><LF>') + # Commands that have not been implemented + def smtp_EXPN(self, arg): + self.push('502 EXPN not implemented') + - class SMTPServer(asyncore.dispatcher): # SMTPChannel class to use for managing client connections channel_class = SMTPChannel - def __init__(self, localaddr, remoteaddr): + def __init__(self, localaddr, remoteaddr, + data_size_limit=DATA_SIZE_DEFAULT): self._localaddr = localaddr self._remoteaddr = remoteaddr + self.data_size_limit = data_size_limit asyncore.dispatcher.__init__(self) try: self.create_socket(socket.AF_INET, socket.SOCK_STREAM) @@ -447,7 +597,7 @@ 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) + channel = self.channel_class(self, conn, addr, self.data_size_limit) # API for "doing something useful with the message" def process_message(self, peer, mailfrom, rcpttos, data): @@ -475,7 +625,6 @@ class SMTPServer(asyncore.dispatcher): raise NotImplementedError - class DebuggingServer(SMTPServer): # Do something with the gathered message def process_message(self, peer, mailfrom, rcpttos, data): @@ -491,7 +640,6 @@ class DebuggingServer(SMTPServer): print('------------ END MESSAGE ------------') - class PureProxy(SMTPServer): def process_message(self, peer, mailfrom, rcpttos, data): lines = data.split('\n') @@ -532,7 +680,6 @@ class PureProxy(SMTPServer): return refused - class MailmanProxy(PureProxy): def process_message(self, peer, mailfrom, rcpttos, data): from io import StringIO @@ -611,19 +758,18 @@ class MailmanProxy(PureProxy): msg.Enqueue(mlist, torequest=1) - class Options: setuid = 1 classname = 'PureProxy' + size_limit = None - def parseargs(): global DEBUGSTREAM try: opts, args = getopt.getopt( - sys.argv[1:], 'nVhc:d', - ['class=', 'nosetuid', 'version', 'help', 'debug']) + sys.argv[1:], 'nVhc:s:d', + ['class=', 'nosetuid', 'version', 'help', 'size=', 'debug']) except getopt.error as e: usage(1, e) @@ -640,6 +786,13 @@ def parseargs(): options.classname = arg elif opt in ('-d', '--debug'): DEBUGSTREAM = sys.stderr + 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) # parse the rest of the arguments if len(args) < 1: @@ -674,7 +827,6 @@ def parseargs(): return options - if __name__ == '__main__': options = parseargs() # Become nobody @@ -687,7 +839,8 @@ if __name__ == '__main__': import __main__ as mod class_ = getattr(mod, classname) proxy = class_((options.localhost, options.localport), - (options.remotehost, options.remoteport)) + (options.remotehost, options.remoteport), + options.size_limit) if options.setuid: try: import pwd |