1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
:mod:`smtpd` --- SMTP Server
============================
.. module:: smtpd
:synopsis: A SMTP server implementation in Python.
.. moduleauthor:: Barry Warsaw <barry@zope.com>
.. sectionauthor:: Moshe Zadka <moshez@moshez.org>
**Source code:** :source:`Lib/smtpd.py`
--------------
This module offers several classes to implement SMTP (email) servers.
Several server implementations are present; one is a generic
do-nothing implementation, which can be overridden, while the other two offer
specific mail-sending strategies.
Additionally the SMTPChannel may be extended to implement very specific
interaction behaviour with SMTP clients.
SMTPServer Objects
------------------
.. class:: SMTPServer(localaddr, remoteaddr)
Create a new :class:`SMTPServer` object, which binds to local address
*localaddr*. It will treat *remoteaddr* as an upstream SMTP relayer. It
inherits from :class:`asyncore.dispatcher`, and so will insert itself into
:mod:`asyncore`'s event loop on instantiation.
.. method:: process_message(peer, mailfrom, rcpttos, data)
Raise :exc:`NotImplementedError` exception. Override this in subclasses to
do something useful with this message. Whatever was passed in the
constructor as *remoteaddr* will be available as the :attr:`_remoteaddr`
attribute. *peer* is the remote host's address, *mailfrom* is the envelope
originator, *rcpttos* are the envelope recipients and *data* is a string
containing the contents of the e-mail (which should be in :rfc:`2822`
format).
.. attribute:: channel_class
Override this in subclasses to use a custom :class:`SMTPChannel` for
managing SMTP clients.
DebuggingServer Objects
-----------------------
.. class:: DebuggingServer(localaddr, remoteaddr)
Create a new debugging server. Arguments are as per :class:`SMTPServer`.
Messages will be discarded, and printed on stdout.
PureProxy Objects
-----------------
.. class:: PureProxy(localaddr, remoteaddr)
Create a new pure proxy server. Arguments are as per :class:`SMTPServer`.
Everything will be relayed to *remoteaddr*. Note that running this has a good
chance to make you into an open relay, so please be careful.
MailmanProxy Objects
--------------------
.. class:: MailmanProxy(localaddr, remoteaddr)
Create a new pure proxy server. Arguments are as per :class:`SMTPServer`.
Everything will be relayed to *remoteaddr*, unless local mailman configurations
knows about an address, in which case it will be handled via mailman. Note that
running this has a good chance to make you into an open relay, so please be
careful.
SMTPChannel Objects
-------------------
.. class:: SMTPChannel(server, conn, addr)
Create a new :class:`SMTPChannel` object which manages the communication
between the server and a single SMTP client.
To use a custom SMTPChannel implementation you need to override the
:attr:`SMTPServer.channel_class` of your :class:`SMTPServer`.
The :class:`SMTPChannel` has the following instance variables:
.. attribute:: smtp_server
Holds the :class:`SMTPServer` that spawned this channel.
.. attribute:: conn
Holds the socket object connecting to the client.
.. attribute:: addr
Holds the address of the client, the second value returned by
:func:`socket.accept <socket.socket.accept>`
.. attribute:: received_lines
Holds a list of the line strings (decoded using UTF-8) received from
the client. The lines have their ``"\r\n"`` line ending translated to
``"\n"``.
.. attribute:: smtp_state
Holds the current state of the channel. This will be either
:attr:`COMMAND` initially and then :attr:`DATA` after the client sends
a "DATA" line.
.. attribute:: seen_greeting
Holds a string containing the greeting sent by the client in its "HELO".
.. attribute:: mailfrom
Holds a string containing the address identified in the "MAIL FROM:" line
from the client.
.. attribute:: rcpttos
Holds a list of strings containing the addresses identified in the
"RCPT TO:" lines from the client.
.. attribute:: received_data
Holds a string containing all of the data sent by the client during the
DATA state, up to but not including the terminating ``"\r\n.\r\n"``.
.. attribute:: fqdn
Holds the fully-qualified domain name of the server as returned by
:func:`socket.getfqdn`.
.. attribute:: peer
Holds the name of the client peer as returned by ``conn.getpeername()``
where ``conn`` is :attr:`conn`.
The :class:`SMTPChannel` operates by invoking methods named ``smtp_<command>``
upon reception of a command line from the client. Built into the base
:class:`SMTPChannel` class are methods for handling the following commands
(and responding to them appropriately):
======== ===================================================================
Command Action taken
======== ===================================================================
HELO Accepts the greeting from the client and stores it in
:attr:`seen_greeting`.
NOOP Takes no action.
QUIT Closes the connection cleanly.
MAIL Accepts the "MAIL FROM:" syntax and stores the supplied address as
:attr:`mailfrom`.
RCPT Accepts the "RCPT TO:" syntax and stores the supplied addresses in
the :attr:`rcpttos` list.
RSET Resets the :attr:`mailfrom`, :attr:`rcpttos`, and
:attr:`received_data`, but not the greeting.
DATA Sets the internal state to :attr:`DATA` and stores remaining lines
from the client in :attr:`received_data` until the terminator
``"\r\n.\r\n"`` is received.
======== ===================================================================
|
