#8739: upgrade smtpd to RFC 5321 and 1870.

smtpd now handles EHLO and has infrastructure for extended smtp command mode.
The SIZE extension is also implemented.  In order to support parameters on
MAIL FROM, the RFC 5322 parser from the email package is used to parse the
address "token".

Logging subclasses things and overrides __init__, so it was necessary to
update those __init__ functions in the logging tests to make the logging tests
pass.

The original suggestion and patch were by Alberto Trevino.  Juhana Jauhiainen
added the --size argument and SIZE parameter support.  Michele Orrù improved
the patch and added more tests.  Dan Boswell conditionalized various bits of
code on whether or not we are in HELO or EHLO mode, as well as some other
improvements and tests.  I finalized the patch and added the address parsing.

1 files changed, 17 insertions, 3 deletions

diff --git a/Doc/library/smtpd.rst b/Doc/library/smtpd.rst
index c391f710df..82f476344a 100644
--- a/Doc/library/smtpd.rst
+++ b/Doc/library/smtpd.rst
@@ -20,17 +20,24 @@ specific mail-sending strategies.
 Additionally the SMTPChannel may be extended to implement very specific
 interaction behaviour with SMTP clients.
 
+The code supports :RFC:`5321`, plus the :rfc:`1870` SIZE extension.
+
+
 SMTPServer Objects
 ------------------
 
 
-.. class:: SMTPServer(localaddr, remoteaddr)
+.. class:: SMTPServer(localaddr, remoteaddr, data_size_limit=33554432)
 
    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.
 
+   *data_size_limit* specifies the maximum number of bytes that will be
+   accepted in a ``DATA`` command.  A value of ``None`` or ``0`` means no
+   limit.
+
    .. method:: process_message(peer, mailfrom, rcpttos, data)
 
       Raise :exc:`NotImplementedError` exception. Override this in subclasses to
@@ -155,11 +162,15 @@ SMTPChannel Objects
    Command  Action taken
    ======== ===================================================================
    HELO     Accepts the greeting from the client and stores it in
-            :attr:`seen_greeting`.
+            :attr:`seen_greeting`.  Sets server to base command mode.
+   EHLO     Accepts the greeting from the client and stores it in
+            :attr:`seen_greeting`.  Sets server to extended command mode.
    NOOP     Takes no action.
    QUIT     Closes the connection cleanly.
    MAIL     Accepts the "MAIL FROM:" syntax and stores the supplied address as
-            :attr:`mailfrom`.
+            :attr:`mailfrom`.  In extended command mode, accepts the
+            :rfc:`1870` SIZE attribute and responds appropriately based on the
+            value of ``data_size_limit``.
    RCPT     Accepts the "RCPT TO:" syntax and stores the supplied addresses in
             the :attr:`rcpttos` list.
    RSET     Resets the :attr:`mailfrom`, :attr:`rcpttos`, and
@@ -167,4 +178,7 @@ SMTPChannel Objects
    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.
+   HELP     Returns minimal information on command syntax
+   VRFY     Returns code 252 (the server doesn't know if the address is valid)
+   EXPN     Reports that the command is not implemented.
    ======== ===================================================================