Twisted Mail SMTPConnectError strange behaviour

esmtp.py

# Copyright (c) 2015 Adi Roiban.
# MIT License
"""
(E)SMTP high level client.
"""
from email.header import Header
from email.mime.application import MIMEApplication
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.utils import formataddr, formatdate, make_msgid
from StringIO import StringIO
from time import time

from twisted.internet import defer, error, reactor
from twisted.internet.error import ConnectError
from twisted.internet.protocol import connectionDone
from twisted.mail import smtp


class ESMTPClient(object):
    """
    High level API for sending messages over the ESMTP protocol.

    Supports only ascii username/password combinations.

    FIXME:3067:
    Twisted does not allow unicode usernames/passwords.
    """
    _reactor = reactor

    # For testing purposes.
    _boundary = None

    def __init__(
            self,
            host,
            port=25,
            username=None,
            password=None,
            retries=3,
            timeout=15,
            ):
        self._host = host
        self._port = port
        self._username = username
        self._password = password
        self._retries = retries
        self._timeout = timeout

    def _formatAddressesAsHeader(self, addresses):
        """
        Returns an email Header instance containing a comma separated list
        of mailboxes`.

        `Addresses` is a list of tuples in the form (name, email). ASCII
        only email addresses are supported.

        https://tools.ietf.org/html/rfc788#page-25
        http://www.rfc-base.org/txt/rfc-2821.txt
        """
        # FIXME:3067:
        # Implement support for non ASCII email name/address.
        charset = 'us-ascii'

        header = Header(charset=charset)
        for address in addresses:
            item = '%s,' % formataddr(address)
            header.append(item, charset=charset, errors='strict')
        return header

    def _buildContent(
            self,
            sender,
            recipients,
            subject,
            body,
            id=None,
            attachments=None,
            ):
        """
        Returns plain text email data header and body as a utf-8 encoded
        byte string.

        Unicode subject and body values are supported and will be encoded
        as utf-8.
        """
        if not id:
            id = make_msgid()

        if not attachments:
            attachments = {}

        destinations = []
        for email in recipients:
            # FIXME:3068:
            # Named email addresses not supported.
            destinations.append(('', email))

        # FIXME:3069:
        # Configurable sender name not supported.
        source = [('TwistedClient', sender)]

        charset = 'utf-8'
        message = MIMEMultipart(boundary=self._boundary)
        message['From'] = self._formatAddressesAsHeader(source)
        message['To'] = self._formatAddressesAsHeader(destinations)
        message['Subject'] = Header(subject, charset=charset)
        message['Date'] = formatdate(time(), localtime=True)
        message['Message-Id'] = id

        message_body = MIMEText(body.encode(charset), 'plain', charset)

        message.attach(message_body)

        for name, attachment in attachments.items():
            attachment.seek(0)
            part = MIMEApplication(attachment.read(), Name=name)
            part['Content-Disposition'] = (
                u'attachment; filename="%s"' % (name,))
            message.attach(part)

        return message.as_string()

    def send(
        self,
        sender,
        recipients,
        subject,
        body,
        id=None,
        attachments=None,
            ):
        """
        Sends email with `subject`, `body` and (optionally) `attachments`
        to `recipients`, from specified `sender`.

        `sender` is a string email address in the format
        `address@example.com`.

        `recipients` a list of string email addresses in the format
        `address@example.com`.

        `attachments` is a dictionary each key of which contains a
        file name and each value contains file-like object
        (e.g. `io.BytesIO`).

        Returns a deferred that will fire once the email is send and the
        server connection terminated. If email was delivered to all specified
        recipients the result will be `True`, otherwise `False`.

        For each call a new connection to the (E)SMTP server is made and
        subsequently dropped.
        """
        connector = None

        def bb_disconnect(result_or_failure):
            """
            If not connected, return `result_or_failure` immediately;
            otherwise wait for disconnection from server to occur and return
            `result_or_failure`.
            """
            if not connector:
                return result_or_failure

            if not connector.transport:
                # Not yet connected.
                return result_or_failure

            if not connector.factory.currentProtocol:
                # Connected, but STMP was not started or was already stopped.
                return result_or_failure

            # Wait for current connection to close.
            deferred = connector.factory.currentProtocol.disconnected_deferred
            deferred.addCallback(lambda _: result_or_failure)
            return deferred

        send_deferred = defer.Deferred()
        send_deferred.addCallback(self._cbSend, recipients)
        send_deferred.addErrback(self._ebSend)
        send_deferred.addBoth(bb_disconnect)

        content = self._buildContent(
            sender, recipients, subject, body, id=id, attachments=attachments)
        factory = SenderFactory(
            username=self._username,
            password=self._password,
            fromEmail=sender,
            toEmail=recipients,
            file=StringIO(content),
            deferred=send_deferred,
            retries=self._retries,
            timeout=self._timeout,
            )
        connector = self._reactor.connectTCP(
            self._host, self._port, factory, timeout=self._timeout)

        return send_deferred

    def _cbSend(self, result, recipients):
        """
        Called when email was delivered successfully.

        Returns `True` if mail was delivered to all recipients, `False`
        otherwise.

        FIXME:3071:
        Return detailed success/failure results.
        """
        successful, details = result

        if len(recipients) == successful:
            # Email delivered successfully to all recipients.
            return True

        return False

    def _ebSend(self, failure):
        """
        Called when email delivery failed or there are connection errors.
        """
        failure.trap(ConnectError, smtp.SMTPClientError)

        # FIXME:3070:
        # Create email client dedicated exceptions a la HTTPException.
        if isinstance(failure.value, smtp.SMTPClientError):
            message = u'%d %s' % (
                failure.value.code, unicode(failure.value.resp))
        else:
            message = unicode(failure.getErrorMessage())

        raise RuntimeError(message.encode('utf-8'))


class ESMTPClientProtocol(smtp.ESMTPSender):
    """
    A ESMTP client protocol that fires an internal deferred once connection
    with server is terminated.
    """

    #: A deferred which is called when protocol is not connected.
    disconnected_deferred = defer.succeed(None)

    def connectionMade(self):
        """
        See: `SMTPSender`.
        """
        smtp.ESMTPSender.connectionMade(self)
        self.disconnected_deferred = defer.Deferred()

    def connectionLost(self, reason=connectionDone):
        """
        See: `SMTPClient`.
        """
        smtp.SMTPClient.connectionLost(self, reason)
        self.disconnected_deferred.callback(None)


class SenderFactory(smtp.ESMTPSenderFactory):
    """
    A factory for simple sending of emails.
    """
    protocol = ESMTPClientProtocol

    def __init__(
        self, username, password, fromEmail, toEmail, file, deferred,
        retries, timeout,
            ):
        if username:
            encoded_username = username.encode('utf-8')
        else:
            encoded_username = None

        if password:
            encoded_password = password.encode('utf-8')
        else:
            encoded_password = None

        smtp.ESMTPSenderFactory.__init__(
            self,
            username=encoded_username,
            password=encoded_password,
            fromEmail=fromEmail,
            toEmail=toEmail,
            file=file,
            deferred=deferred,
            retries=retries,
            timeout=timeout,
            requireAuthentication=False,
            requireTransportSecurity=False,
            heloFallback=1,
            )

    def _processConnectionError(self, connector, err):
        self.currentProtocol = None
        if (self.retries < 0) and (not self.sendFinished):
            # Rewind the file in case part of it was read while attempting to
            # send the message.
            self.file.seek(0, 0)
            connector.connect()
            self.retries += 1
        elif not self.sendFinished:
            # If we were unable to communicate with the SMTP server a
            # ConnectionDone will be returned.
            # We want a more clear error message for debugging
            if err.check(error.ConnectionDone):
                err.value = smtp.SMTPConnectError(
                    -1, "Unable to connect to server.")
            self.result.errback(err.value)

http.py

# Copyright (c) 2014 Adi Roiban.
# MIT License
"""
Helpers for testing code related to HTTP protocol.
"""
from __future__ import absolute_import

from httplib import HTTPConnection, HTTPSConnection
from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
from select import error as SelectError
from StringIO import StringIO
from threading import Thread
import codecs
import errno
import json
from httplib import BadStatusLine
import socket
import ssl
import threading
import time
import urllib

from twisted.internet import defer, interfaces as internet_interfaces
from twisted.python.failure import Failure
from twisted.web import (
    http,
    server as web_server,
    )
from twisted.web.client import ResponseDone
from twisted.web.http_headers import Headers
from twisted.web.iweb import IBodyProducer
from twisted.web.server import Request
from zope.interface import implementer


# Marker used to signal that the expected request will have a streamed body.
STREAMED_REQUEST = object()
STREAMED_RESPONSE = object()


@implementer(internet_interfaces.IPushProducer)
class InMemoryBodyDeliverer(object):
    """
    A wrapper to externalized the stubbing of data received by the response.
    """

    def __init__(self, consumer):
        self._consumer = consumer
        self._consumer.transport = self
        self.stopped = False
        self.paused = False

    def pauseProducing(self):
        self.paused = True

    def resumeProducing(self):
        self.paused = False

    def stopProducing(self):
        self.stopped = True

    def sendData(self, data):
        """
        Simulate a data received from the response.
        """
        if self.stopped:
            raise AssertionError('Data received after producer was stopped.')

        if self.paused:
            raise AssertionError('Data received while paused.')

        self._consumer.dataReceived(data)

    def stopSending(self):
        """
        Simulate that the body delivered has sent all the data, as signaled
        by closing the connection.
        """
        self._consumer.connectionLost(Failure(ResponseDone()))


class InMemoryResponse(object):
    """
    Simple response from in memory agent request.
    """
    def __init__(
        self, method='GET', code=404, phrase='Phrase not set',
        request_body=None, request_json=None, request_headers=None,
        response_body=b'', response_headers={},
            ):
        self.method = method
        self.code = code
        self.phrase = phrase
        self.request_headers = Headers(request_headers)

        if request_body is not None:
            request_body = request_body
        elif request_json is not None:
            request_body = json.dumps(request_json)
        else:
            request_body = ''
        self.request_body = request_body

        self.response_body = response_body
        self.headers = Headers(response_headers)

        self._stream_request = False
        self._streamed_body = None

    @property
    def streamed_body(self):
        """
        The content of the requested as it was streamed.
        """
        return self._streamed_body

    def write(self, data):
        """
        Called when received a streamed request.
        """
        if self.request_body != STREAMED_REQUEST:
            raise AssertionError('Write while not in stream mode.')

        if not isinstance(data, bytes):
            raise AssertionError('Write operation for non bytes.')

        if self._streamed_body is None:
            self._streamed_body = data
        else:
            self._streamed_body += data

    def deliverBody(self, consumer_protocol):
        """
        See: twisted.web.client.Response.deliverBody.
        """
        producer = InMemoryBodyDeliverer(consumer_protocol)
        if self.response_body == STREAMED_RESPONSE:
            self.body_producer = producer
            return

        consumer_protocol.dataReceived(self.response_body)
        consumer_protocol.connectionLost(Failure(ResponseDone()))


class InMemoryPersistentAgent(object):
    """
    Simple implementation of an HTTP Persistent Agent.
    """

    def __init__(self):
        self._connections = {}
        self.responses = {}

    def _getResponse(self, method, url, headers, body):
        """
        Return the arranged response for our rigged agent.
        """
        if body is None:
            body = ''

        self._cacheURL(url)
        headers = Headers(headers)
        try:
            response = self.responses[url].pop(0)
        except (KeyError, IndexError):
            raise AssertionError(
                'URL not defined %s for %s' % (method, url))

        if isinstance(response, Exception):
            return defer.fail(response)

        if isinstance(response, defer.Deferred):
            deferred = response
        else:
            deferred = defer.succeed(response)

        def cb_check_response(response):
            """
            Called when we got a response.
            """
            if response.method != method:
                raise AssertionError(
                    'No %s request was defined for %s' % (method, url))

            if IBodyProducer.providedBy(body):
                # We have a streamed request, so the body is checked later.
                if response.request_body != STREAMED_REQUEST:
                    raise AssertionError(
                        'Unexpected streamed request. Expecting: %s' % (
                            response.request_body,))

                done_deferred = body.startProducing(response)
                response.start_producing_deferred = done_deferred
            else:
                # Just compare the whole body.
                if response.request_body != body:
                    raise AssertionError(
                        'Invalid request body:\ngot\n%s\nexpecting\n%s' % (
                            body, response.request_body))

            if response.request_headers != headers:
                raise AssertionError(
                    'Invalid headers:\ngot\n%s\nexpecting\n%s' % (
                        headers, response.request_headers))
            # All good.
            return response

        deferred.addCallback(cb_check_response)
        return deferred

    def _cacheURL(self, url):
        """
        Called to mark that URL is cached.
        """
        # For connection caching we cache only based on host.
        parts = url.split('/', 3)
        if len(parts) > 3:
            host = '/'.join(parts[:-1])
        else:
            host = url

        self._connections[host] = b'cached'

    def postJSON(self, url, body, headers=None):
        """
        See: PersistentAgent.
        """
        if headers is None:
            headers = {}

        # Make sure content type is always JSON.
        headers['Content-Type'] = [b'application/json; charset=utf-8']

        return self.post(url, headers, json.dumps(body).encode('utf-8'))

    def post(self, url, headers, body):
        """
        See: PersistentAgent.
        """
        return self._getResponse(b'POST', url, headers, body)

    def put(self, url, headers, body):
        """
        See: PersistentAgent.
        """
        return self._getResponse(b'PUT', url, headers, body)

    def get(self, url, headers):
        """
        See: PersistentAgent.
        """
        return self._getResponse(b'GET', url, headers, body=None)

    def delete(self, url, headers):
        """
        See: PersistentAgent.
        """
        return self._getResponse(b'DELETE', url, headers, body=None)

    def propfind(self, url, headers):
        """
        See: PersistentAgent.
        """
        return self._getResponse(b'PROPFIND', url, headers, body=None)

    def mkcol(self, url, headers):
        """
        See: PersistentAgent.
        """
        return self._getResponse(b'MKCOL', url, headers, body=None)

    def head(self, url, headers):
        """
        See: PersistentAgent.
        """
        return self._getResponse(b'HEAD', url, headers, body=None)

    def move(self, url, headers):
        """
        See: PersistentAgent.
        """
        return self._getResponse(b'MOVE', url, headers, body=None)

    def readBody(self, response):
        """
        Return a deferred which fires with response body.
        """
        return defer.succeed(response.response_body)

    def closePersistentConnections(self):
        """
        See: PersistentAgent.
        """
        self._connections = {}

    @property
    def connections(self):
        """
        Return the list of persistent connections.
        """
        return self._connections


class DummyHTTPChannel(object):
    port = 80
    disconnected = False

    def __init__(self, site=None, peer=None, host=None, resource=None):
        from chevah.server.testing import mk
        self.written = StringIO()
        self.producers = []
        if peer is None:
            peer = mk.makeIPv4Address(host='42.0.0.1', port=1234)

        if host is None:
            host = mk.makeIPv4Address(host='10.0.0.1', port=self.port)

        if site is None:
            site = web_server.Site(resource)

        self.site = site
        self._peer = peer
        self._host = host

    def getPeer(self):
        return self._peer

    def write(self, data):
        if not isinstance(data, bytes):
            raise AssertionError('Non bytes write request.')
        self.written.write(bytes)

    def writeSequence(self, iovec):
        map(self.write, iovec)

    def getHost(self):
        return self._host

    def registerProducer(self, producer, streaming):
        self.producers.append((producer, streaming))

    def loseConnection(self):
        self.disconnected = True

    def requestDone(self, request):
        pass


@implementer(internet_interfaces.ISSLTransport)
class DummyHTTPSChannel(DummyHTTPChannel):
    port = 443


class DummyWebRequest(Request):
    """
    A dummy Twisted Web Request used in tests.

    uri - url encoded
    postpath, prepath - utf-8 encoded (not Unicode)
    """

    def __init__(
        self,
        postpath=None, prepath=None, session=None, resource=None,
        data=None, peer=None, site=None,
        uri=None, clientproto=None, method=None, secured=False,
        path=None, host=None, channel=None
            ):
        from chevah.server.testing import mk
        if peer is None:
            peer = mk.makeIPv4Address(host='42.0.0.1')

        if channel is None:
            channel = DummyHTTPChannel(peer=peer, host=host, site=site)
        self.channel = channel
        self.site = channel.site

        self.content = StringIO()
        self.written = []

        if data:
            self.content.write(data)
            self.content.seek(0)

        # Full URL including arguments
        if uri is None:
            uri = '/uri-not-defined'
        elif postpath is not None:
            raise AssertionError('You can not define both URI and postpath.')
        self.uri = uri

        # HTTP URL arguments POST or GET
        self.args = {}

        # HTTP URL without arguments
        self.path = path

        if prepath is None:
            prepath = []

        if postpath is None:
            postpath = self.uri.split('/')[1:]
        else:
            self.uri = urllib.quote('/%s' % '/'.join(postpath + prepath))

        if isinstance(uri, unicode):
            raise AssertionError('URI should be URL encoded.')

        self.sitepath = []

        self.prepath = prepath
        self.postpath = postpath
        self.client = peer

        self.secured = secured

        if clientproto is None:
            clientproto = 'HTTP/1.0'
        self.clientproto = clientproto

        if method is None:
            method = 'GET'
        self.method = method.upper()

        self.session = None
        self.protoSession = session or web_server.Session(0, self)

        self._code = http.OK
        self._code_message = 'OK'

        self.responseHeaders = Headers()
        self.requestHeaders = Headers()

        # This should be called after we have defined the request headers.
        if host is None:
            host = 'dummy.host.tld'
        self.setRequestHeader('host', host)

        self.received_cookies = {}
        self.cookies = []  # outgoing cookies

        # Finish notifications
        self.notifications = []

        self.finished = 0

        self.queued = False

    def __repr__(self):
        return (
            'DummyWebRequest for "%(uri)s", code: %(code)s\n'
            'response content: "%(response_content)s"\n'
            'response headers: "%(response_headers)s' % ({
                'uri': self.uri,
                'code': self.code,
                'response_content': self.test_response_content,
                'response_headers': dict(
                    self.responseHeaders.getAllRawHeaders()),
                })
            )

    @property
    def code(self):
        return self._code

    @property
    def code_message(self):
        return self._code_message

    @property
    def test_response_content(self):
        """
        Return the data written to the request during tests.
        """
        return ''.join(self.written)

    def _checkContentNotWritten(self, method_name):
        """
        Check that content was not sent to remote peer.

        `method_name` is there to help pinpoint where things went wrong.
        """
        assert not self.written, (
            "%s cannot be called after data has been written: %s." % (
                method_name, "@@@@".join(self.written)))

    def getSession(self, sessionInterface=None):
        """
        Return server sided stored session object.
        """
        if not self.session:
            self._checkContentNotWritten('getSession')
        return super(DummyWebRequest, self).getSession(sessionInterface)

    def write(self, data):
        if not isinstance(data, bytes):
            raise AssertionError("Non bytes write request.")
        self.written.append(data)

    def isSecure(self):
        return self.secured

    def getHeader(self, name):
        """
        Public method for a Request.
        """
        value = self.requestHeaders.getRawHeaders(name)
        if value is not None:
            return value[-1]

    def setHeader(self, name, value):
        """
        Public method for a Request.
        """
        self.responseHeaders.setRawHeaders(name, [value])

    def getRequestHeader(self, name):
        """
        Testing method to get request headers.

        This is here so that we can have clear/explicit tests.
        """
        return self.getHeader(name)

    def setRequestHeader(self, name, value):
        """
        Testing method to set request headers.

        This is here so that we can have clear/explicit tests.
        """
        self.requestHeaders.setRawHeaders(name.lower(), [value])

    def getResponseHeader(self, name):
        """
        Testing method to get response headers.

        This is here so that we can have clear/explicit tests.
        """
        value = self.responseHeaders.getRawHeaders(name)
        if value is not None:
            return value[-1]

    def setResponseHeader(self, name, value):
        """
        Testing method to set response headers.

        This is here so that we can have clear/explicit tests.
        """
        self.setHeader(self, name, value)

    def setLastModified(self, when):
        """
        See: twisted.web.http.Request.
        """
        self._checkContentNotWritten('setLastModified')
        return super(DummyWebRequest, self).setLastModified(when)

    def setETag(self, tag):
        """
        See: twisted.web.http.Request.

        Just checks that method is not called after response was sent.
        """
        self._checkContentNotWritten('setETag')

    def getCookie(self, key):
        """
        Get an incoming HTTP cookie.
        """
        return self.received_cookies.get(key, None)

    def setReceivedCookie(self, key, value):
        """
        Set cookie as it were received in the request.
        """
        self.received_cookies[key] = value

    def redirect(self, url):
        """
        Utility function that does a redirect.

        The request should have finish() called after this.
        """
        self.setResponseCode(http.FOUND)
        self.setHeader("location", url)

    def registerProducer(self, prod, s):
        """
        See: twisted.web.http.Request.
        """
        self.go = 1
        while self.go:
            prod.resumeProducing()

    def unregisterProducer(self):
        """
        See: twisted.web.http.Request.
        """
        self.go = 0

    def processingFailed(self, reason):
        """
        Errback and L{Deferreds} waiting for finish notification.
        """
        if self.notifications is not None:
            observers = self.notifications
            self.notifications = None
            for obs in observers:
                obs.errback(reason)

    def setResponseCode(self, code, message=None):
        """
        Set the HTTP status response code, but takes care that this is called
        before any data is written.
        """
        self._checkContentNotWritten('setResponseCode')
        # Code and code_message are read-only for our test purpose.
        self._code = code
        self._code_message = message

    def render(self, resource):
        """
        Render the given resource as a response to this request.

        This implementation only handles a few of the most common behaviors of
        resources.  It can handle a render method that returns a string or
        C{NOT_DONE_YET}.  It doesn't know anything about the semantics of
        request methods (eg HEAD) nor how to set any particular headers.
        Basically, it's largely broken, but sufficient for some tests at
        least.
        It should B{not} be expanded to do all the same stuff L{Request} does.
        Instead, L{DummyRequest} should be phased out and L{Request} (or some
        other real code factored in a different way) used.
        """
        result = resource.render(self)
        if result is web_server.NOT_DONE_YET:
            return
        self.write(result)
        self.finish()

    def setRequestContent(self, data):
        """
        Set body content of the request.
        """
        self.content.write(data)
        self.content.seek(0)


class _StoppableHTTPServer(HTTPServer):
    """
    Single connection HTTP server designed to respond to HTTP requests in
    functional tests.
    """
    server_version = 'ChevahTesting/0.1'
    stopped = False
    # Current connection served by the server.
    active_connection = None

    def serve_forever(self):
        """
        Handle one request at a time until stopped.
        """
        self.stopped = False
        self.active_connection = None
        while not self.stopped:
            try:
                self.handle_request()
            except SelectError as e:
                # See Python http://bugs.python.org/issue7978
                if e.args[0] == errno.EINTR:
                    continue
                raise
            except socket.error as error:
                if error.errno == errno.EBADF:
                    self.stopped = True
                else:
                    break


class _ThreadedHTTPServer(Thread):
    """
    HTTP or HTTPS Server that runs in a thread.

    This is actual a threaded wrapper around an HTTP server.
    """
    TIMEOUT = 1

    def __init__(
        self, handler_class, cond,
        responses=None,
        ip='127.0.0.1', port=0,
        server_certificate=None,
        debug=False,
            ):
        Thread.__init__(self)
        self.ready = False
        self.cond = cond
        self._ip = ip
        self._port = port
        self._handler_class = handler_class
        self._server_certificate = server_certificate

    def run(self):
        self.cond.acquire()
        timeout = 0
        self.httpd = None
        while self.httpd is None:
            try:
                self.httpd = _StoppableHTTPServer(
                    (self._ip, self._port), self._handler_class)
                if self._server_certificate:
                    self.httpd.socket = ssl.wrap_socket(
                        self.httpd.socket,
                        certfile=self._server_certificate,
                        server_side=True,
                        )
            except Exception as e:
                # I have no idea why this code works.
                # It is a copy paste from:
                # http://www.ianlewis.org/en/testing-using-mocked-server
                import errno
                import time
                if (isinstance(e, socket.error) and
                        errno.errorcode[e.args[0]] == 'EADDRINUSE' and
                        timeout < self.TIMEOUT):
                    timeout += 1
                    time.sleep(1)
                else:
                    self.cond.notifyAll()
                    self.cond.release()
                    self.ready = True
                    raise e

        self.ready = True
        if self.cond:
            self.cond.notifyAll()
            self.cond.release()
        # Start the actual HTTP server.
        self.httpd.serve_forever()


class HTTPServerContext(object):
    """
    A context manager which runs a HTTP or HTTPS server for testing simple
    HTTP requests.

    After the server is started the ip and port are available in the
    context management instance.

    response = ResponseDefinition(url='/hello.html', response_content='Hello!)
    with HTTPServerContext([response]) as httpd:
        print 'Listening at %s:%d' % (httpd.id, httpd.port)
        self.assertEqual('Hello!', your_get())

    responses = ResponseDefinition(
        url='/hello.php', request='user=John',
        response_content='Hello John!, response_code=202)
    with HTTPServerContext([response]) as httpd:
        self.assertEqual(
            'Hello John!',
            get_you_post(url='hello.php', data='user=John'))
    """

    def __init__(
            self, responses=None, ip='127.0.0.1', port=0,
            version='HTTP/1.1', cert=None, debug=False,
            ):
        """
        Initialize a new HTTPServerContext.

         * ip - IP to listen. Leave empty to listen to any interface.
         * port - Port to listen. Leave 0 to pick a random port.
         * server_version - HTTP version used by server.
         * responses - A list of ResponseDefinition defining the behavior of
                        this server.
         * cert - certificate to be used by the HTTPS server.
        """
        self._previous_valid_responses = _DefinedRequestHandler.valid_responses
        self._previous_first_client = _DefinedRequestHandler.first_client

        # Since we can not pass an instance of _DefinedRequestHandler
        # we do on the fly patching here.
        # Servers might be nested, so a debug will trigger any server.
        # Also, this has the side effect, that once a debug is enabled in
        # one tests, it will be enabled in all the tests after it, so we
        # keep the state at start to see if we should revert.
        self._debug = debug
        self._previous_debug = _DefinedRequestHandler.debug
        _DefinedRequestHandler.debug = _DefinedRequestHandler.debug or debug
        if responses is None:
            _DefinedRequestHandler.valid_responses = []
        else:
            _DefinedRequestHandler.valid_responses = responses

        _DefinedRequestHandler.protocol_version = version
        self.cond = threading.Condition()
        self._server_certificate = cert
        self.server = _ThreadedHTTPServer(
            handler_class=_DefinedRequestHandler,
            cond=self.cond,
            ip=ip,
            port=port,
            server_certificate=cert,
            )

    def __enter__(self):
        self.cond.acquire()
        self.server.start()

        # Wait until the server is ready.
        while not self.server.ready:
            self.cond.wait()
        self.cond.release()

        # Even if the thread ready, it might still need some time
        # to be ready.
        time.sleep(0.02)

        return self

    def __exit__(self, exc_type, exc_value, tb):
        # _DefinedRequestHandler initialization is outside of control so
        # we share state as class members. To free memory we need to clean it.
        _DefinedRequestHandler.cleanGlobals()

        if self._debug and not self._previous_debug:
            _DefinedRequestHandler.debug = False

        self.stopServer()
        self.server.join(1)

        # The reverting should be done after the thread is closed so that
        # we don't have things inside the thread setting the class values.
        _DefinedRequestHandler.valid_responses = self._previous_valid_responses
        _DefinedRequestHandler.first_client = self._previous_first_client

        if self.server.isAlive():
            raise AssertionError('Server still running')

        return False

    @property
    def port(self):
        return self.server.httpd.server_address[1]

    @property
    def ip(self):
        return self.server.httpd.server_address[0]

    def stopServer(self):
        connection = self.server.httpd.active_connection
        try:
            if connection and connection.rfile._sock:
                # Stop waiting for data from persistent connection.
                self.server.httpd.stopped = True
                sock = connection.rfile._sock
                sock.shutdown(socket.SHUT_RDWR)
                sock.close()
            else:
                # Stop waiting for data from new connection.
                # This is done by sending a special QUIT request without
                # waiting for data.
                address = '%s:%d' % (self.ip, self.port)
                if self._server_certificate:
                    try:
                        context = ssl._create_unverified_context()
                    except Exception:
                        # Python < 2.7.9 uses the old HTTPS code.
                        context = None

                    if context:
                        # Use an HTTPS connection since we are in HTTPS mode.
                        conn = HTTPSConnection(
                            address, context=context, timeout=5)
                    else:
                        conn = HTTPSConnection(address, timeout=5)
                else:
                    conn = HTTPConnection(address, timeout=5)
                conn.request("QUIT", "/")
                conn.getresponse()
        except (socket.error, BadStatusLine):
            # Ignore socket errors at shutdown as the connection
            # might be already closed.
            pass

        self.server.httpd.server_close()


class _DefinedRequestHandler(BaseHTTPRequestHandler, object):
    """
    A request handler which act based on pre-defined responses.

    This should only be used for test together with HTTPServerContext.
    """

    valid_responses = []

    debug = False
    # Keep a record of first client which connects to the request
    # series to have a better check for persisted connections.
    first_client = None

    def __init__(self, request, client_address, server):
        if self.debug:
            print('New connection %s.' % (client_address,))
        # Register current connection on server.
        server.active_connection = self
        try:
            super(_DefinedRequestHandler, self).__init__(
                request, client_address, server)
        except socket.error:
            pass
        server.active_connection = None

    @classmethod
    def cleanGlobals(cls):
        """
        Clean all class methods used to share info between different requests.
        """
        cls.valid_responses = []
        cls.first_client = None

    def log_message(self, *args):
        """
        We don't want any logs from the server.
        """
        pass

    def do_QUIT(self):
        """
        Called by HTTPServerContext to trigger server stop.
        """
        self.server.stopped = True
        self._debug('QUIT')
        self.send_response(200)
        self.end_headers()
        # Force closing the connection.
        self.close_connection = 1

    def do_GET(self):
        self._handleRequest()

    def do_HEAD(self):
        self._handleRequest()

    def do_POST(self):
        self._handleRequest()

    def do_PUT(self):
        self._handleRequest()

    def do_DELETE(self):
        self._handleRequest()

    def do_PROPFIND(self):
        self._handleRequest()

    def _handleRequest(self):
        """
        Check if we can handle the request and send response.
        """
        if not self.first_client:
            # Looks like this is the first request so we save the client
            # address to compare it later.
            self._debug('First: %r' % (self.client_address,))
            self.__class__.first_client = self.client_address

        response = self._matchResponse()
        if response:
            self._debug(response)
            self._sendResponse(response)
            self._debug(
                'After: Close-connection: %s' % (self.close_connection,))
            return

        self.send_error(404)

    def _matchResponse(self):
        """
        Return the ResponseDefinition for the current request.
        """
        for response in self.__class__.valid_responses:
            if self.path != response.url or self.command != response.method:
                self._debug()
                continue

            # For POST request we read content.
            if self.command != 'GET':
                length = int(self.headers.getheader('content-length', 0))
                content = self.rfile.read(length)
                if content != response.request:
                    self._debug(content)
                    continue

            # We have a match.
            return response

        return None

    def _debug(self, message=''):
        """
        Print to stdout a debug message.
        """
        if not self.debug:
            return
        print('\nGot %s:%s - %s\n' % (
            self.command, self.path, message))

    def _sendResponse(self, response):
        """
        Send response to client.
        """
        connection_header = self.headers.getheader('connection')
        if connection_header:
            connection_header = connection_header.lower()

        if self.protocol_version == 'HTTP/1.1':
            # For HTTP/1.1 connections are persistent by default.
            if not connection_header:
                connection_header = 'keep-alive'
        else:
            # For HTTP/1.0 connections are not persistent by default.
            if not connection_header:
                connection_header = 'close'

        if response.persistent is None:
            # Ignore persistent flag.
            pass
        elif response.persistent:
            if connection_header == 'close':
                self.send_error(400, 'Headers do not persist the connection')

            if self.first_client != self.client_address:
                self.send_error(
                    400,
                    'Persistent connection not reused. First %r. Now %r' % (
                        self.first_client, self.client_address))
        else:
            if connection_header == 'keep-alive':
                self.send_error(400, 'Connection was persistent')

        if isinstance(response.response_code, Exception):
            # Just close the connection without a valid HTTP response.
            self.wfile.write(response.response_code.message)
            self.close_connection = 1
            return

        self.send_response(
            response.response_code, response.response_message)
        self.send_header("Content-Type", response.content_type)

        if response.response_length:
            self.send_header("Content-Length", response.response_length)

        self.end_headers()
        self.wfile.write(response.test_response_content)

        if not response.response_persistent:
            # Force closing the connection as requested
            # by response.
            self.close_connection = 1


class ResponseDefinition(object):
    """
    A class encapsulating the required data for configuring a response
    generated by the HTTPServerContext.

    It contains the following data:
        * url - url that will trigger this response
        * request - request that will trigger the response once the url is
                    matched
        * response_content - content of the response
        * response_code - HTTP code of the response or an Exception().
          If the Exception has any text, it is written to the response as raw
          data.
        * response_message - Message sent together with HTTP code.
        * content_type - Content type of the HTTP response
        * response_length - Length of the response body content.
          `None` to calculate automatically the length.
          `` (empty string) to ignore content-length header.
        * persistent: whether the request should persist the connection.
          Set to None to ignore persistent checking.
    """

    def __init__(
        self, url='', request='', method='GET',
        response_content=b'', response_code=200, response_message=None,
        content_type=b'text/html', response_length=None,
        persistent=True, response_persistent=None,
            ):
        self.url = url
        self.method = method
        self.request = request
        if not isinstance(response_content, bytes):
            response_content = codecs.encode(response_content, 'utf-8')
        self.test_response_content = response_content
        self.response_code = response_code
        self.response_message = response_message
        self.content_type = content_type
        if response_length is None:
            response_length = len(self.test_response_content)
        self.response_length = str(response_length)
        self.persistent = persistent
        if response_persistent is None:
            response_persistent = persistent

        self.response_persistent = response_persistent

    def __repr__(self):
        return 'ResponseDefinition:%s:%s:%s %s:pers-%s' % (
            self.url,
            self.method,
            self.response_code, self.response_message,
            self.persistent,
            )

    def updateResponseContent(self, content):
        """
        Will update the content returned to the server.
        """
        if not isinstance(content, bytes):
            content = codecs.encode(content, 'utf-8')

        self.test_response_content = content
        response_length = len(self.test_response_content)
        self.response_length = str(response_length)

requirements.txt

chevah-compat==0.45.2
twisted
nose
bunch
scandir
remote_pdb
unidecode
mock
ld

test.py

"""
Test to demonstrate a strange behaviour of SMTPConnectError.

To give it a try.

$ virtualenv build
$ . build/bin/activate
$ pip install -r requirements.txt
$ nosetests test.py
OR
$ trial --force-gc ./test.py
"""
from __future__ import absolute_import, unicode_literals
from contextlib import contextmanager
import os
import sys
# This is so that we can run as trial ./test.py
sys.path.append(os.getcwd())

from bunch import Bunch
from twisted.internet import defer, reactor
from twisted.internet.error import ConnectionClosed
from twisted.internet.protocol import ServerFactory, Protocol
from twisted.web.client import (
    Agent,
    HTTPConnectionPool,
    ResponseNeverReceived,
    )

from chevah.compat.testing import ChevahTestCase

from esmtp import ESMTPClient
from http import HTTPServerContext, ResponseDefinition


def serverFactoryForProtocol(protocol_class):
    """
    Create a new factory instance for `protocol_class`.
    """
    factory = ServerFactory()
    factory.protocol = protocol_class
    factory.protocol_instance = None
    factory.protocol_instances = []
    factory.protocol_open_deferred = defer.Deferred()
    return factory


class RejectPeerProtocol(Protocol):
    """
    A protocol which will reject any connection.
    """
    def connectionMade(self):
        self.transport.loseConnection()


class TestCase(ChevahTestCase):
    """
    There are 2 tests here. If SMTP tests is executed first, the HTTP will
    fail as it will get the STMP error.
    If HTTP tests is first, all is fine.
    """

    @contextmanager
    def listenTCP(self, protocol_class, address='127.0.0.1', port=0):
        """"
        Return a context which open a TCP/IP socket.

        At the context exit the listening socket is closed together with
        all accepted sockets.
        """
        factory = serverFactoryForProtocol(protocol_class)
        listening_port = None
        try:
            listening_port = reactor.listenTCP(
                interface=address,
                port=port,
                factory=factory,
                )
            local_peer = listening_port.getHost()
            context = Bunch(
                port=local_peer.port,
                address=local_peer.host,
                connector=port,
                factory=factory,
                )

            yield context

        finally:
            for connection in factory.protocol_instances:
                connection.loseConnection()

            if not listening_port:  # pragma: no branch
                return

            # Wait for the listening port to close.
            deferred = listening_port.stopListening()
            self.getDeferredResult(deferred)

    def getAgent(self):
        """
        Return a new PersistentAgent instance.
        """
        agent = Agent(
            reactor=reactor,
            pool=HTTPConnectionPool(
                reactor=reactor, persistent=True),
            )
        self.addCleanup(self.closeAgent, agent)
        return agent

    def closeAgent(self, agent):
        try:
            deferred = agent._pool.closeCachedConnections()
            self.getDeferredResult(deferred)
        finally:
            self.executeReactor()

    def test_1_send_server_rejection(self):
        """
        This will trigger the STMPConnectError
        """
        with self.listenTCP(protocol_class=RejectPeerProtocol) as server:
            sut = ESMTPClient(
                host=server.address, port=server.port, retries=0)

            deferred = sut.send(
                sender='sender@ingore.com',
                recipients=['dst@ignore.com'],
                subject='[SUBJ] Ignored',
                body='some content ignored',
                )

            failure = self.getDeferredFailure(deferred, prevent_stop=True)
            self.assertStartsWith(
                '-1 Unable to connect to server.',
                failure.value.message
                )

    def test_2_makeRequest_agent_wrap(self):
        """
        This is a test in which STMPConnectError is a side effect.

        HTTP Agent will wrap the error in an ResponseNeverReceived with the
        original reason passed as a list.

        The failure is unwrapped and the request will get the direct failure.
        """
        sut = self.getAgent()
        response = ResponseDefinition(
            method=b'GET',
            url='/endpoint',
            request=b'',
            # We don't write anything on the response to trigger the behavior
            # described in the docstring.
            response_code=Exception(b''),
            persistent=True,
            )

        with HTTPServerContext([response]) as server:
            url = 'http://%s:%s/endpoint' % (server.ip, server.port)
            deferred = sut.request(method=b'GET', uri=url.encode('utf-8'))

            failure = self.getDeferredFailure(deferred, prevent_stop=True)

        self.assertIsInstance(ResponseNeverReceived, failure.value)
        inner_failure = failure.value[0][0]
        self.assertIsInstance(ConnectionClosed, inner_failure.value)

    def test_3_makeRequest_agent_wrap(self):
        """
        This is another test in which STMPConnectError is a side effect.

        HTTP Agent will wrap the error in an ResponseNeverReceived with the
        original reason passed as a list.

        The failure is unwrapped and the request will get the direct failure.
        """
        sut = self.getAgent()
        response = ResponseDefinition(
            method=b'GET',
            url='/endpoint',
            request=b'',
            # We don't write anything on the response to trigger the behavior
            # described in the docstring.
            response_code=Exception(b''),
            persistent=True,
            )

        with HTTPServerContext([response]) as server:
            url = 'http://%s:%s/endpoint' % (server.ip, server.port)
            deferred = sut.request(method=b'GET', uri=url.encode('utf-8'))

            failure = self.getDeferredFailure(deferred, prevent_stop=True)

        self.assertIsInstance(ResponseNeverReceived, failure.value)
        inner_failure = failure.value[0][0]
        self.assertIsInstance(ConnectionClosed, inner_failure.value)