import asyncore
import email.mime.text
import email.utils
import socket
import smtpd
import smtplib
import io
import re
import sys
import time
import select

import unittest
from test import support, mock_socket

try:
    import threading
except ImportError:
    threading = None

HOST = support.HOST

if sys.platform == 'darwin':
    # select.poll returns a select.POLLHUP at the end of the tests
    # on darwin, so just ignore it
    def handle_expt(self):
        pass
    smtpd.SMTPChannel.handle_expt = handle_expt


def server(evt, buf, serv):
    serv.listen(5)
    evt.set()
    try:
        conn, addr = serv.accept()
    except socket.timeout:
        pass
    else:
        n = 500
        while buf and n > 0:
            r, w, e = select.select([], [conn], [])
            if w:
                sent = conn.send(buf)
                buf = buf[sent:]

            n -= 1

        conn.close()
    finally:
        serv.close()
        evt.set()

class GeneralTests(unittest.TestCase):

    def setUp(self):
        smtplib.socket = mock_socket
        self.port = 25

    def tearDown(self):
        smtplib.socket = socket

    # This method is no longer used but is retained for backward compatibility,
    # so test to make sure it still works.
    def testQuoteData(self):
        teststr  = "abc\n.jkl\rfoo\r\n..blue"
        expected = "abc\r\n..jkl\r\nfoo\r\n...blue"
        self.assertEqual(expected, smtplib.quotedata(teststr))

    def testBasic1(self):
        mock_socket.reply_with(b"220 Hola mundo")
        # connects
        smtp = smtplib.SMTP(HOST, self.port)
        smtp.close()

    def testBasic2(self):
        mock_socket.reply_with(b"220 Hola mundo")
        # connects, include port in host name
        smtp = smtplib.SMTP("%s:%s" % (HOST, self.port))
        smtp.close()

    def testLocalHostName(self):
        mock_socket.reply_with(b"220 Hola mundo")
        # check that supplied local_hostname is used
        smtp = smtplib.SMTP(HOST, self.port, local_hostname="testhost")
        self.assertEqual(smtp.local_hostname, "testhost")
        smtp.close()

    def testTimeoutDefault(self):
        mock_socket.reply_with(b"220 Hola mundo")
        self.assertTrue(mock_socket.getdefaulttimeout() is None)
        mock_socket.setdefaulttimeout(30)
        self.assertEqual(mock_socket.getdefaulttimeout(), 30)
        try:
            smtp = smtplib.SMTP(HOST, self.port)
        finally:
            mock_socket.setdefaulttimeout(None)
        self.assertEqual(smtp.sock.gettimeout(), 30)
        smtp.close()

    def testTimeoutNone(self):
        mock_socket.reply_with(b"220 Hola mundo")
        self.assertTrue(socket.getdefaulttimeout() is None)
        socket.setdefaulttimeout(30)
        try:
            smtp = smtplib.SMTP(HOST, self.port, timeout=None)
        finally:
            socket.setdefaulttimeout(None)
        self.assertTrue(smtp.sock.gettimeout() is None)
        smtp.close()

    def testTimeoutValue(self):
        mock_socket.reply_with(b"220 Hola mundo")
        smtp = smtplib.SMTP(HOST, self.port, timeout=30)
        self.assertEqual(smtp.sock.gettimeout(), 30)
        smtp.close()


# Test server thread using the specified SMTP server class
def debugging_server(serv, serv_evt, client_evt):
    serv_evt.set()

    try:
        if hasattr(select, 'poll'):
            poll_fun = asyncore.poll2
        else:
            poll_fun = asyncore.poll

        n = 1000
        while asyncore.socket_map and n > 0:
            poll_fun(0.01, asyncore.socket_map)

            # when the client conversation is finished, it will
            # set client_evt, and it's then ok to kill the server
            if client_evt.is_set():
                serv.close()
                break

            n -= 1

    except socket.timeout:
        pass
    finally:
        if not client_evt.is_set():
            # allow some time for the client to read the result
            time.sleep(0.5)
            serv.close()
        asyncore.close_all()
        serv_evt.set()

MSG_BEGIN = '---------- MESSAGE FOLLOWS ----------\n'
MSG_END = '------------ END MESSAGE ------------\n'

# NOTE: Some SMTP objects in the tests below are created with a non-default
# local_hostname argument to the constructor, since (on some systems) the FQDN
# lookup caused by the default local_hostname sometimes takes so long that the
# test server times out, causing the test to fail.

# Test behavior of smtpd.DebuggingServer
@unittest.skipUnless(threading, 'Threading required for this test.')
class DebuggingServerTests(unittest.TestCase):

    maxDiff = None

    def setUp(self):
        self.real_getfqdn = socket.getfqdn
        socket.getfqdn = mock_socket.getfqdn
        # temporarily replace sys.stdout to capture DebuggingServer output
        self.old_stdout = sys.stdout
        self.output = io.StringIO()
        sys.stdout = self.output

        self.serv_evt = threading.Event()
        self.client_evt = threading.Event()
        # Capture SMTPChannel debug output
        self.old_DEBUGSTREAM = smtpd.DEBUGSTREAM
        smtpd.DEBUGSTREAM = io.StringIO()
        # Pick a random unused port by passing 0 for the port number
        self.serv = smtpd.DebuggingServer((HOST, 0), ('nowhere', -1))
        # Keep a note of what port was assigned
        self.port = self.serv.socket.getsockname()[1]
        serv_args = (self.serv, self.serv_evt, self.client_evt)
        self.thread = threading.Thread(target=debugging_server, args=serv_args)
        self.thread.start()

        # wait until server thread has assigned a port number
        self.serv_evt.wait()
        self.serv_evt.clear()

    def tearDown(self):
        socket.getfqdn = self.real_getfqdn
        # indicate that the client is finished
        self.client_evt.set()
        # wait for the server thread to terminate
        self.serv_evt.wait()
        self.thread.join()
        # restore sys.stdout
        sys.stdout = self.old_stdout
        # restore DEBUGSTREAM
        smtpd.DEBUGSTREAM.close()
        smtpd.DEBUGSTREAM = self.old_DEBUGSTREAM

    def testBasic(self):
        # connect
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.quit()

    def testNOOP(self):
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        expected = (250, b'Ok')
        self.assertEqual(smtp.noop(), expected)
        smtp.quit()

    def testRSET(self):
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        expected = (250, b'Ok')
        self.assertEqual(smtp.rset(), expected)
        smtp.quit()

    def testNotImplemented(self):
        # EHLO isn't implemented in DebuggingServer
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        expected = (502, b'Error: command "EHLO" not implemented')
        self.assertEqual(smtp.ehlo(), expected)
        smtp.quit()

    def testVRFY(self):
        # VRFY isn't implemented in DebuggingServer
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        expected = (502, b'Error: command "VRFY" not implemented')
        self.assertEqual(smtp.vrfy('nobody@nowhere.com'), expected)
        self.assertEqual(smtp.verify('nobody@nowhere.com'), expected)
        smtp.quit()

    def testSecondHELO(self):
        # check that a second HELO returns a message that it's a duplicate
        # (this behavior is specific to smtpd.SMTPChannel)
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.helo()
        expected = (503, b'Duplicate HELO/EHLO')
        self.assertEqual(smtp.helo(), expected)
        smtp.quit()

    def testHELP(self):
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        self.assertEqual(smtp.help(), b'Error: command "HELP" not implemented')
        smtp.quit()

    def testSend(self):
        # connect and send mail
        m = 'A test message'
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.sendmail('John', 'Sally', m)
        # XXX(nnorwitz): this test is flaky and dies with a bad file descriptor
        # in asyncore.  This sleep might help, but should really be fixed
        # properly by using an Event variable.
        time.sleep(0.01)
        smtp.quit()

        self.client_evt.set()
        self.serv_evt.wait()
        self.output.flush()
        mexpect = '%s%s\n%s' % (MSG_BEGIN, m, MSG_END)
        self.assertEqual(self.output.getvalue(), mexpect)

    def testSendBinary(self):
        m = b'A test message'
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.sendmail('John', 'Sally', m)
        # XXX (see comment in testSend)
        time.sleep(0.01)
        smtp.quit()

        self.client_evt.set()
        self.serv_evt.wait()
        self.output.flush()
        mexpect = '%s%s\n%s' % (MSG_BEGIN, m.decode('ascii'), MSG_END)
        self.assertEqual(self.output.getvalue(), mexpect)

    def testSendNeedingDotQuote(self):
        # Issue 12283
        m = '.A test\n.mes.sage.'
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.sendmail('John', 'Sally', m)
        # XXX (see comment in testSend)
        time.sleep(0.01)
        smtp.quit()

        self.client_evt.set()
        self.serv_evt.wait()
        self.output.flush()
        mexpect = '%s%s\n%s' % (MSG_BEGIN, m, MSG_END)
        self.assertEqual(self.output.getvalue(), mexpect)

    def testSendNullSender(self):
        m = 'A test message'
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.sendmail('<>', 'Sally', m)
        # XXX (see comment in testSend)
        time.sleep(0.01)
        smtp.quit()

        self.client_evt.set()
        self.serv_evt.wait()
        self.output.flush()
        mexpect = '%s%s\n%s' % (MSG_BEGIN, m, MSG_END)
        self.assertEqual(self.output.getvalue(), mexpect)
        debugout = smtpd.DEBUGSTREAM.getvalue()
        sender = re.compile("^sender: <>$", re.MULTILINE)
        self.assertRegex(debugout, sender)

    def testSendMessage(self):
        m = email.mime.text.MIMEText('A test message')
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.send_message(m, from_addr='John', to_addrs='Sally')
        # XXX (see comment in testSend)
        time.sleep(0.01)
        smtp.quit()

        self.client_evt.set()
        self.serv_evt.wait()
        self.output.flush()
        # Add the X-Peer header that DebuggingServer adds
        m['X-Peer'] = socket.gethostbyname('localhost')
        mexpect = '%s%s\n%s' % (MSG_BEGIN, m.as_string(), MSG_END)
        self.assertEqual(self.output.getvalue(), mexpect)

    def testSendMessageWithAddresses(self):
        m = email.mime.text.MIMEText('A test message')
        m['From'] = 'foo@bar.com'
        m['To'] = 'John'
        m['CC'] = 'Sally, Fred'
        m['Bcc'] = 'John Root <root@localhost>, "Dinsdale" <warped@silly.walks.com>'
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.send_message(m)
        # XXX (see comment in testSend)
        time.sleep(0.01)
        smtp.quit()
        # make sure the Bcc header is still in the message.
        self.assertEqual(m['Bcc'], 'John Root <root@localhost>, "Dinsdale" '
                                    '<warped@silly.walks.com>')

        self.client_evt.set()
        self.serv_evt.wait()
        self.output.flush()
        # Add the X-Peer header that DebuggingServer adds
        m['X-Peer'] = socket.gethostbyname('localhost')
        # The Bcc header should not be transmitted.
        del m['Bcc']
        mexpect = '%s%s\n%s' % (MSG_BEGIN, m.as_string(), MSG_END)
        self.assertEqual(self.output.getvalue(), mexpect)
        debugout = smtpd.DEBUGSTREAM.getvalue()
        sender = re.compile("^sender: foo@bar.com$", re.MULTILINE)
        self.assertRegex(debugout, sender)
        for addr in ('John', 'Sally', 'Fred', 'root@localhost',
                     'warped@silly.walks.com'):
            to_addr = re.compile(r"^recips: .*'{}'.*$".format(addr),
                                 re.MULTILINE)
            self.assertRegex(debugout, to_addr)

    def testSendMessageWithSomeAddresses(self):
        # Make sure nothing breaks if not all of the three 'to' headers exist
        m = email.mime.text.MIMEText('A test message')
        m['From'] = 'foo@bar.com'
        m['To'] = 'John, Dinsdale'
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.send_message(m)
        # XXX (see comment in testSend)
        time.sleep(0.01)
        smtp.quit()

        self.client_evt.set()
        self.serv_evt.wait()
        self.output.flush()
        # Add the X-Peer header that DebuggingServer adds
        m['X-Peer'] = socket.gethostbyname('localhost')
        mexpect = '%s%s\n%s' % (MSG_BEGIN, m.as_string(), MSG_END)
        self.assertEqual(self.output.getvalue(), mexpect)
        debugout = smtpd.DEBUGSTREAM.getvalue()
        sender = re.compile("^sender: foo@bar.com$", re.MULTILINE)
        self.assertRegex(debugout, sender)
        for addr in ('John', 'Dinsdale'):
            to_addr = re.compile(r"^recips: .*'{}'.*$".format(addr),
                                 re.MULTILINE)
            self.assertRegex(debugout, to_addr)

    def testSendMessageWithSpecifiedAddresses(self):
        # Make sure addresses specified in call override those in message.
        m = email.mime.text.MIMEText('A test message')
        m['From'] = 'foo@bar.com'
        m['To'] = 'John, Dinsdale'
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.send_message(m, from_addr='joe@example.com', to_addrs='foo@example.net')
        # XXX (see comment in testSend)
        time.sleep(0.01)
        smtp.quit()

        self.client_evt.set()
        self.serv_evt.wait()
        self.output.flush()
        # Add the X-Peer header that DebuggingServer adds
        m['X-Peer'] = socket.gethostbyname('localhost')
        mexpect = '%s%s\n%s' % (MSG_BEGIN, m.as_string(), MSG_END)
        self.assertEqual(self.output.getvalue(), mexpect)
        debugout = smtpd.DEBUGSTREAM.getvalue()
        sender = re.compile("^sender: joe@example.com$", re.MULTILINE)
        self.assertRegex(debugout, sender)
        for addr in ('John', 'Dinsdale'):
            to_addr = re.compile(r"^recips: .*'{}'.*$".format(addr),
                                 re.MULTILINE)
            self.assertNotRegex(debugout, to_addr)
        recip = re.compile(r"^recips: .*'foo@example.net'.*$", re.MULTILINE)
        self.assertRegex(debugout, recip)

    def testSendMessageWithMultipleFrom(self):
        # Sender overrides To
        m = email.mime.text.MIMEText('A test message')
        m['From'] = 'Bernard, Bianca'
        m['Sender'] = 'the_rescuers@Rescue-Aid-Society.com'
        m['To'] = 'John, Dinsdale'
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.send_message(m)
        # XXX (see comment in testSend)
        time.sleep(0.01)
        smtp.quit()

        self.client_evt.set()
        self.serv_evt.wait()
        self.output.flush()
        # Add the X-Peer header that DebuggingServer adds
        m['X-Peer'] = socket.gethostbyname('localhost')
        mexpect = '%s%s\n%s' % (MSG_BEGIN, m.as_string(), MSG_END)
        self.assertEqual(self.output.getvalue(), mexpect)
        debugout = smtpd.DEBUGSTREAM.getvalue()
        sender = re.compile("^sender: the_rescuers@Rescue-Aid-Society.com$", re.MULTILINE)
        self.assertRegex(debugout, sender)
        for addr in ('John', 'Dinsdale'):
            to_addr = re.compile(r"^recips: .*'{}'.*$".format(addr),
                                 re.MULTILINE)
            self.assertRegex(debugout, to_addr)

    def testSendMessageResent(self):
        m = email.mime.text.MIMEText('A test message')
        m['From'] = 'foo@bar.com'
        m['To'] = 'John'
        m['CC'] = 'Sally, Fred'
        m['Bcc'] = 'John Root <root@localhost>, "Dinsdale" <warped@silly.walks.com>'
        m['Resent-Date'] = 'Thu, 1 Jan 1970 17:42:00 +0000'
        m['Resent-From'] = 'holy@grail.net'
        m['Resent-To'] = 'Martha <my_mom@great.cooker.com>, Jeff'
        m['Resent-Bcc'] = 'doe@losthope.net'
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        smtp.send_message(m)
        # XXX (see comment in testSend)
        time.sleep(0.01)
        smtp.quit()

        self.client_evt.set()
        self.serv_evt.wait()
        self.output.flush()
        # The Resent-Bcc headers are deleted before serialization.
        del m['Bcc']
        del m['Resent-Bcc']
        # Add the X-Peer header that DebuggingServer adds
        m['X-Peer'] = socket.gethostbyname('localhost')
        mexpect = '%s%s\n%s' % (MSG_BEGIN, m.as_string(), MSG_END)
        self.assertEqual(self.output.getvalue(), mexpect)
        debugout = smtpd.DEBUGSTREAM.getvalue()
        sender = re.compile("^sender: holy@grail.net$", re.MULTILINE)
        self.assertRegex(debugout, sender)
        for addr in ('my_mom@great.cooker.com', 'Jeff', 'doe@losthope.net'):
            to_addr = re.compile(r"^recips: .*'{}'.*$".format(addr),
                                 re.MULTILINE)
            self.assertRegex(debugout, to_addr)

    def testSendMessageMultipleResentRaises(self):
        m = email.mime.text.MIMEText('A test message')
        m['From'] = 'foo@bar.com'
        m['To'] = 'John'
        m['CC'] = 'Sally, Fred'
        m['Bcc'] = 'John Root <root@localhost>, "Dinsdale" <warped@silly.walks.com>'
        m['Resent-Date'] = 'Thu, 1 Jan 1970 17:42:00 +0000'
        m['Resent-From'] = 'holy@grail.net'
        m['Resent-To'] = 'Martha <my_mom@great.cooker.com>, Jeff'
        m['Resent-Bcc'] = 'doe@losthope.net'
        m['Resent-Date'] = 'Thu, 2 Jan 1970 17:42:00 +0000'
        m['Resent-To'] = 'holy@grail.net'
        m['Resent-From'] = 'Martha <my_mom@great.cooker.com>, Jeff'
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
        with self.assertRaises(ValueError):
            smtp.send_message(m)
        smtp.close()

class NonConnectingTests(unittest.TestCase):

    def setUp(self):
        smtplib.socket = mock_socket

    def tearDown(self):
        smtplib.socket = socket

    def testNotConnected(self):
        # Test various operations on an unconnected SMTP object that
        # should raise exceptions (at present the attempt in SMTP.send
        # to reference the nonexistent 'sock' attribute of the SMTP object
        # causes an AttributeError)
        smtp = smtplib.SMTP()
        self.assertRaises(smtplib.SMTPServerDisconnected, smtp.ehlo)
        self.assertRaises(smtplib.SMTPServerDisconnected,
                          smtp.send, 'test msg')

    def testNonnumericPort(self):
        # check that non-numeric port raises socket.error
        self.assertRaises(mock_socket.error, smtplib.SMTP,
                          "localhost", "bogus")
        self.assertRaises(mock_socket.error, smtplib.SMTP,
                          "localhost:bogus")


# test response of client to a non-successful HELO message
@unittest.skipUnless(threading, 'Threading required for this test.')
class BadHELOServerTests(unittest.TestCase):

    def setUp(self):
        smtplib.socket = mock_socket
        mock_socket.reply_with(b"199 no hello for you!")
        self.old_stdout = sys.stdout
        self.output = io.StringIO()
        sys.stdout = self.output
        self.port = 25

    def tearDown(self):
        smtplib.socket = socket
        sys.stdout = self.old_stdout

    def testFailingHELO(self):
        self.assertRaises(smtplib.SMTPConnectError, smtplib.SMTP,
                            HOST, self.port, 'localhost', 3)


@unittest.skipUnless(threading, 'Threading required for this test.')
class TooLongLineTests(unittest.TestCase):
    respdata = b'250 OK' + (b'.' * smtplib._MAXLINE * 2) + b'\n'

    def setUp(self):
        self.old_stdout = sys.stdout
        self.output = io.StringIO()
        sys.stdout = self.output

        self.evt = threading.Event()
        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.sock.settimeout(15)
        self.port = support.bind_port(self.sock)
        servargs = (self.evt, self.respdata, self.sock)
        threading.Thread(target=server, args=servargs).start()
        self.evt.wait()
        self.evt.clear()

    def tearDown(self):
        self.evt.wait()
        sys.stdout = self.old_stdout

    def testLineTooLong(self):
        self.assertRaises(smtplib.SMTPResponseException, smtplib.SMTP,
                          HOST, self.port, 'localhost', 3)


sim_users = {'Mr.A@somewhere.com':'John A',
             'Ms.B@xn--fo-fka.com':'Sally B',
             'Mrs.C@somewhereesle.com':'Ruth C',
            }

sim_auth = ('Mr.A@somewhere.com', 'somepassword')
sim_cram_md5_challenge = ('PENCeUxFREJoU0NnbmhNWitOMjNGNn'
                          'dAZWx3b29kLmlubm9zb2Z0LmNvbT4=')
sim_auth_credentials = {
    'login': 'TXIuQUBzb21ld2hlcmUuY29t',
    'plain': 'AE1yLkFAc29tZXdoZXJlLmNvbQBzb21lcGFzc3dvcmQ=',
    'cram-md5': ('TXIUQUBZB21LD2HLCMUUY29TIDG4OWQ0MJ'
                 'KWZGQ4ODNMNDA4NTGXMDRLZWMYZJDMODG1'),
    }
sim_auth_login_password = 'C29TZXBHC3N3B3JK'

sim_lists = {'list-1':['Mr.A@somewhere.com','Mrs.C@somewhereesle.com'],
             'list-2':['Ms.B@xn--fo-fka.com',],
            }

# Simulated SMTP channel & server
class SimSMTPChannel(smtpd.SMTPChannel):

    mail_response = None
    rcpt_response = None
    data_response = None
    rcpt_count = 0
    rset_count = 0

    def __init__(self, extra_features, *args, **kw):
        self._extrafeatures = ''.join(
            [ "250-{0}\r\n".format(x) for x in extra_features ])
        super(SimSMTPChannel, self).__init__(*args, **kw)

    def smtp_EHLO(self, arg):
        resp = ('250-testhost\r\n'
                '250-EXPN\r\n'
                '250-SIZE 20000000\r\n'
                '250-STARTTLS\r\n'
                '250-DELIVERBY\r\n')
        resp = resp + self._extrafeatures + '250 HELP'
        self.push(resp)

    def smtp_VRFY(self, arg):
        # For max compatibility smtplib should be sending the raw address.
        if arg in sim_users:
            self.push('250 %s %s' % (sim_users[arg], smtplib.quoteaddr(arg)))
        else:
            self.push('550 No such user: %s' % arg)

    def smtp_EXPN(self, arg):
        list_name = arg.lower()
        if list_name in sim_lists:
            user_list = sim_lists[list_name]
            for n, user_email in enumerate(user_list):
                quoted_addr = smtplib.quoteaddr(user_email)
                if n < len(user_list) - 1:
                    self.push('250-%s %s' % (sim_users[user_email], quoted_addr))
                else:
                    self.push('250 %s %s' % (sim_users[user_email], quoted_addr))
        else:
            self.push('550 No access for you!')

    def smtp_AUTH(self, arg):
        if arg.strip().lower()=='cram-md5':
            self.push('334 {}'.format(sim_cram_md5_challenge))
            return
        mech, auth = arg.split()
        mech = mech.lower()
        if mech not in sim_auth_credentials:
            self.push('504 auth type unimplemented')
            return
        if mech == 'plain' and auth==sim_auth_credentials['plain']:
            self.push('235 plain auth ok')
        elif mech=='login' and auth==sim_auth_credentials['login']:
            self.push('334 Password:')
        else:
            self.push('550 No access for you!')

    def smtp_MAIL(self, arg):
        if self.mail_response is None:
            super().smtp_MAIL(arg)
        else:
            self.push(self.mail_response)

    def smtp_RCPT(self, arg):
        if self.rcpt_response is None:
            super().smtp_RCPT(arg)
            return
        self.rcpt_count += 1
        self.push(self.rcpt_response[self.rcpt_count-1])

    def smtp_RSET(self, arg):
        self.rset_count += 1
        super().smtp_RSET(arg)

    def smtp_DATA(self, arg):
        if self.data_response is None:
            super().smtp_DATA(arg)
        else:
            self.push(self.data_response)

    def handle_error(self):
        raise


class SimSMTPServer(smtpd.SMTPServer):

    channel_class = SimSMTPChannel

    def __init__(self, *args, **kw):
        self._extra_features = []
        smtpd.SMTPServer.__init__(self, *args, **kw)

    def handle_accepted(self, conn, addr):
        self._SMTPchannel = self.channel_class(self._extra_features,
                                           self, conn, addr)

    def process_message(self, peer, mailfrom, rcpttos, data):
        pass

    def add_feature(self, feature):
        self._extra_features.append(feature)

    def handle_error(self):
        raise


# Test various SMTP & ESMTP commands/behaviors that require a simulated server
# (i.e., something with more features than DebuggingServer)
@unittest.skipUnless(threading, 'Threading required for this test.')
class SMTPSimTests(unittest.TestCase):

    def setUp(self):
        self.real_getfqdn = socket.getfqdn
        socket.getfqdn = mock_socket.getfqdn
        self.serv_evt = threading.Event()
        self.client_evt = threading.Event()
        # Pick a random unused port by passing 0 for the port number
        self.serv = SimSMTPServer((HOST, 0), ('nowhere', -1))
        # Keep a note of what port was assigned
        self.port = self.serv.socket.getsockname()[1]
        serv_args = (self.serv, self.serv_evt, self.client_evt)
        self.thread = threading.Thread(target=debugging_server, args=serv_args)
        self.thread.start()

        # wait until server thread has assigned a port number
        self.serv_evt.wait()
        self.serv_evt.clear()

    def tearDown(self):
        socket.getfqdn = self.real_getfqdn
        # indicate that the client is finished
        self.client_evt.set()
        # wait for the server thread to terminate
        self.serv_evt.wait()
        self.thread.join()

    def testBasic(self):
        # smoke test
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
        smtp.quit()

    def testEHLO(self):
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)

        # no features should be present before the EHLO
        self.assertEqual(smtp.esmtp_features, {})

        # features expected from the test server
        expected_features = {'expn':'',
                             'size': '20000000',
                             'starttls': '',
                             'deliverby': '',
                             'help': '',
                             }

        smtp.ehlo()
        self.assertEqual(smtp.esmtp_features, expected_features)
        for k in expected_features:
            self.assertTrue(smtp.has_extn(k))
        self.assertFalse(smtp.has_extn('unsupported-feature'))
        smtp.quit()

    def testVRFY(self):
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)

        for email, name in sim_users.items():
            expected_known = (250, bytes('%s %s' %
                                         (name, smtplib.quoteaddr(email)),
                                         "ascii"))
            self.assertEqual(smtp.vrfy(email), expected_known)

        u = 'nobody@nowhere.com'
        expected_unknown = (550, ('No such user: %s' % u).encode('ascii'))
        self.assertEqual(smtp.vrfy(u), expected_unknown)
        smtp.quit()

    def testEXPN(self):
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)

        for listname, members in sim_lists.items():
            users = []
            for m in members:
                users.append('%s %s' % (sim_users[m], smtplib.quoteaddr(m)))
            expected_known = (250, bytes('\n'.join(users), "ascii"))
            self.assertEqual(smtp.expn(listname), expected_known)

        u = 'PSU-Members-List'
        expected_unknown = (550, b'No access for you!')
        self.assertEqual(smtp.expn(u), expected_unknown)
        smtp.quit()

    def testAUTH_PLAIN(self):
        self.serv.add_feature("AUTH PLAIN")
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)

        expected_auth_ok = (235, b'plain auth ok')
        self.assertEqual(smtp.login(sim_auth[0], sim_auth[1]), expected_auth_ok)
        smtp.close()

    # SimSMTPChannel doesn't fully support LOGIN or CRAM-MD5 auth because they
    # require a synchronous read to obtain the credentials...so instead smtpd
    # sees the credential sent by smtplib's login method as an unknown command,
    # which results in smtplib raising an auth error.  Fortunately the error
    # message contains the encoded credential, so we can partially check that it
    # was generated correctly (partially, because the 'word' is uppercased in
    # the error message).

    def testAUTH_LOGIN(self):
        self.serv.add_feature("AUTH LOGIN")
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
        try: smtp.login(sim_auth[0], sim_auth[1])
        except smtplib.SMTPAuthenticationError as err:
            self.assertIn(sim_auth_login_password, str(err))
        smtp.close()

    def testAUTH_CRAM_MD5(self):
        self.serv.add_feature("AUTH CRAM-MD5")
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)

        try: smtp.login(sim_auth[0], sim_auth[1])
        except smtplib.SMTPAuthenticationError as err:
            self.assertIn(sim_auth_credentials['cram-md5'], str(err))
        smtp.close()

    #TODO: add tests for correct AUTH method fallback now that the
    #test infrastructure can support it.

    # Issue 5713: make sure close, not rset, is called if we get a 421 error
    def test_421_from_mail_cmd(self):
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
        smtp.noop()
        self.serv._SMTPchannel.mail_response = '421 closing connection'
        with self.assertRaises(smtplib.SMTPSenderRefused):
            smtp.sendmail('John', 'Sally', 'test message')
        self.assertIsNone(smtp.sock)
        self.assertEqual(self.serv._SMTPchannel.rset_count, 0)

    def test_421_from_rcpt_cmd(self):
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
        smtp.noop()
        self.serv._SMTPchannel.rcpt_response = ['250 accepted', '421 closing']
        with self.assertRaises(smtplib.SMTPRecipientsRefused) as r:
            smtp.sendmail('John', ['Sally', 'Frank', 'George'], 'test message')
        self.assertIsNone(smtp.sock)
        self.assertEqual(self.serv._SMTPchannel.rset_count, 0)
        self.assertDictEqual(r.exception.args[0], {'Frank': (421, b'closing')})

    def test_421_from_data_cmd(self):
        class MySimSMTPChannel(SimSMTPChannel):
            def found_terminator(self):
                if self.smtp_state == self.DATA:
                    self.push('421 closing')
                else:
                    super().found_terminator()
        self.serv.channel_class = MySimSMTPChannel
        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
        smtp.noop()
        with self.assertRaises(smtplib.SMTPDataError):
            smtp.sendmail('John@foo.org', ['Sally@foo.org'], 'test message')
        self.assertIsNone(smtp.sock)
        self.assertEqual(self.serv._SMTPchannel.rcpt_count, 0)


@support.reap_threads
def test_main(verbose=None):
    support.run_unittest(GeneralTests, DebuggingServerTests,
                              NonConnectingTests,
                              BadHELOServerTests, SMTPSimTests,
                              TooLongLineTests)

if __name__ == '__main__':
    test_main()