Python3SMTP aiosmtpd代理/中继

Question

我正在尝试使用替换aiosmtpd的新的smtpd库来进行一个开放的SMTP中继。下面的程序实例化传递给邮件控制器的Proxy处理程序，邮件控制器随后在后台启动。然后使用连接到中继的标准smtplib客户端创建消息。

在客户端和中继之间的SMTP会话结束之前，一切都是正常的，直到消息从不离开中继为止。中继从不用250 OK\r\n进行应答，而ctrl+c则表示sendmail正在等待回复。

有什么想法吗？剧本漏掉了什么吗？

编辑：mail.example.com只是一个示例服务器。smtpd DebuggingServer在使用relay = aiosmtpd.handlers.Proxy("localhost", 1025)执行脚本时不会打印任何内容。

$ python3.6 -m smtpd -n -c DebuggingServer -d localhost:1025
DebuggingServer started at Fri Apr  7 18:41:09 2017
    Local addr: ('localhost', 1025)
    Remote addr:('localhost', 25)
...nothing printed out...

剧本：

from aiosmtpd.handlers import Debugging, Proxy
from aiosmtpd.controller import Controller
from smtplib import SMTP

# relay = aiosmtpd.handlers.Debugging()
relay = aiosmtpd.handlers.Proxy("localhost", 1025)
# relay = aiosmtpd.handlers.Proxy("mail.example.com", 25)
controller = Controller(relay)
controller.start()
print(controller, controller.hostname, controller.port)

input("ready... press enter to continue")

print("creating SMTP with debug")
client = SMTP()
client.set_debuglevel(1)
print("connecting to the SMTP server")
client.connect(controller.hostname, controller.port)

print("sending message")
client.sendmail('alice@example.com',
                ['bob@example.com'], """\
From: Alice <alice@example.com>
To: Bob <bob@example.com>
Subject: Title

Body.
""")

print("stopping controller")
controller.stop()
print("checking if controller really stopped")
client.connect(controller.hostname, controller.port)

下面是脚本的输出：

 $ python3.6 relay.py
<aiosmtpd.controller.Controller object at 0x10199f710> ::0 8025
ready... press enter to continue
creating SMTP with debug
connecting to the SMTP server
connect: ('::0', 8025)
connect: to ('::0', 8025) None
reply: b'220 localhost Python SMTP 1.0a4\r\n'
reply: retcode (220); Msg: b'localhost Python SMTP 1.0a4'
connect: b'localhost Python SMTP 1.0a4'
sending message
send: 'ehlo localhost\r\n'
reply: b'250-localhost\r\n'
reply: b'250-SIZE 33554432\r\n'
reply: b'250-8BITMIME\r\n'
reply: b'250 HELP\r\n'
reply: retcode (250); Msg: b'localhost\nSIZE 33554432\n8BITMIME\nHELP'
send: 'mail FROM:<alice@example.com> size=85\r\n'
reply: b'250 OK\r\n'
reply: retcode (250); Msg: b'OK'
send: 'rcpt TO:<bob@example.com>\r\n'
reply: b'250 OK\r\n'
reply: retcode (250); Msg: b'OK'
send: 'data\r\n'
reply: b'354 End data with <CR><LF>.<CR><LF>\r\n'
reply: retcode (354); Msg: b'End data with <CR><LF>.<CR><LF>'
data: (354, b'End data with <CR><LF>.<CR><LF>')
send: b'From: Alice <alice@example.com>\r\nTo: Bob <bob@example.com>\r\nSubject: Title\r\n\r\nBody.\r\n.\r\n'

...nothing happens at this point...

^CTraceback (most recent call last):
  File "relay.py", line 49, in <module>
    """)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/smtplib.py", line 881, in sendmail
    (code, resp) = self.data(msg)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/smtplib.py", line 568, in data
    (code, msg) = self.getreply()
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/smtplib.py", line 386, in getreply
    line = self.file.readline(_MAXLINE + 1)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/socket.py", line 586, in readinto
    return self._sock.recv_into(b)
KeyboardInterrupt

为了进行比较，下面是使用调试处理程序的输出：

 $ python3.6 relay.py
<aiosmtpd.controller.Controller object at 0x10189f710> ::0 8025
ready... press enter to continue
creating SMTP with debug
connecting to the SMTP server
connect: ('::0', 8025)
connect: to ('::0', 8025) None
reply: b'220 localhost Python SMTP 1.0a4\r\n'
reply: retcode (220); Msg: b'localhost Python SMTP 1.0a4'
connect: b'localhost Python SMTP 1.0a4'
sending message
send: 'ehlo localhost\r\n'
reply: b'250-localhost\r\n'
reply: b'250-SIZE 33554432\r\n'
reply: b'250-8BITMIME\r\n'
reply: b'250 HELP\r\n'
reply: retcode (250); Msg: b'localhost\nSIZE 33554432\n8BITMIME\nHELP'
send: 'mail FROM:<alice@example.com> size=85\r\n'
reply: b'250 OK\r\n'
reply: retcode (250); Msg: b'OK'
send: 'rcpt TO:<bob@example.com>\r\n'
reply: b'250 OK\r\n'
reply: retcode (250); Msg: b'OK'
send: 'data\r\n'
reply: b'354 End data with <CR><LF>.<CR><LF>\r\n'
reply: retcode (354); Msg: b'End data with <CR><LF>.<CR><LF>'
data: (354, b'End data with <CR><LF>.<CR><LF>')
send: b'From: Alice <alice@example.com>\r\nTo: Bob <bob@example.com>\r\nSubject: Title\r\n\r\nBody.\r\n.\r\n'
---------- MESSAGE FOLLOWS ----------
mail options: ['SIZE=85']
rcpt options: []

From: Alice <alice@example.com>
To: Bob <bob@example.com>
Subject: Title
X-Peer: ('::1', 64397, 0, 0)

Body.
------------ END MESSAGE ------------
reply: b'250 OK\r\n'
reply: retcode (250); Msg: b'OK'
data: (250, b'OK')
stopping controller
checking if controller really stopped
connect: ('::0', 8025)
connect: to ('::0', 8025) None
Traceback (most recent call last):
  File "relay.py", line 51, in <module>
    client.connect(controller.hostname, controller.port)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/smtplib.py", line 335, in connect
    self.sock = self._get_socket(host, port, self.timeout)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/smtplib.py", line 306, in _get_socket
    self.source_address)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/socket.py", line 722, in create_connection
    raise err
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/socket.py", line 713, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 61] Connection refused

Answer 1

编辑：在aiosmtpd 1.0b1中，bug是固定，所以升级应该解决这个问题。

在aiosmtpd 1.0a4中，Proxy.handle_DATA中的一个未察觉的异常(使用data作为str而不是字节)将导致异步任务停止，但异常永远不会被传播。

如果升级到1.0a5，则会正确地打印异常："Error：(TypeError)不能在类似字节的对象上使用字符串模式“。问题是，从1.0a5开始，aiosmtpd中的Proxy被设计用于在aiosmtpd.smtp.SMTP对象上设置decode_data=True的Controller子类中使用，但是默认情况下，会导致错误的decode_data=False。(在我看来，Proxy应该改为使用decode_data=False，因此我打开了PR #74。)

因此，要在aiosmtpd1.0a4或1.0a5中使用代理，需要从UTF8Controller中复制和使用aiosmtpd/tests/test_handlers.py子类。我已经用1.0a4和1.0a5测试了以下脚本：

from aiosmtpd.handlers import Debugging, Proxy
from aiosmtpd.controller import Controller
from aiosmtpd.smtp import SMTP as SMTPServer
from smtplib import SMTP as SMTPClient

class UTF8Controller(Controller):
    def factory(self):
        return SMTPServer(self.handler, decode_data=True)

# relay = Debugging()
relay = Proxy("localhost", 1025)
# relay = Proxy("mail.example.com", 25)
controller = UTF8Controller(relay)
controller.start()
print(controller, controller.hostname, controller.port)

input("ready... press enter to continue")

print("creating SMTP with debug")
client = SMTPClient()
client.set_debuglevel(1)
print("connecting to the SMTP server")
client.connect(controller.hostname, controller.port)

print("sending message")
client.sendmail('alice@example.com',
                ['bob@example.com'], """\
From: Alice <alice@example.com>
To: Bob <bob@example.com>
Subject: Title

Body.
""")

print("stopping controller")
controller.stop()
print("checking if controller really stopped")
client.connect(controller.hostname, controller.port)