exchangelib.protocol API documentation
Description: A protocol is an endpoint for EWS service connections. It contains all necessary information to make HTTPS connections …

# Module `exchangelib.protocol`

A protocol is an endpoint for EWS service connections. It contains all necessary information to make HTTPS connections.

Protocols should be accessed through an Account, and are either created from a default Configuration or autodiscovered when creating an Account.

Expand source code

    """
    A protocol is an endpoint for EWS service connections. It contains all necessary information to make HTTPS connections.

    Protocols should be accessed through an Account, and are either created from a default Configuration or autodiscovered
    when creating an Account.
    """

    import abc
    import datetime
    import logging
    import random
    from contextlib import suppress
    from queue import Empty, LifoQueue
    from threading import Lock

    import requests.adapters
    import requests.sessions
    from oauthlib.oauth2 import BackendApplicationClient
    from requests_oauthlib import OAuth2Session

    from .credentials import BaseOAuth2Credentials
    from .errors import (
        CASError,
        ErrorInternalServerTransientError,
        ErrorInvalidSchemaVersionForMailboxVersion,
        ErrorServerBusy,
        InvalidTypeError,
        MalformedResponseError,
        RateLimitError,
        RedirectError,
        RelativeRedirect,
        SessionPoolMaxSizeReached,
        SessionPoolMinSizeReached,
        TransportError,
        UnauthorizedError,
    )
    from .properties import (
        ENTRY_ID,
        EWS_ID,
        AlternateId,
        DLMailbox,
        FreeBusyViewOptions,
        MailboxData,
        RoomList,
        TimeWindow,
        TimeZone,
    )
    from .services import (
        ConvertId,
        ExpandDL,
        GetRoomLists,
        GetRooms,
        GetSearchableMailboxes,
        GetServerTimeZones,
        GetUserAvailability,
        ResolveNames,
    )
    from .transport import CREDENTIALS_REQUIRED, DEFAULT_HEADERS, NTLM, OAUTH2, get_auth_instance, get_service_authtype
    from .util import _get_retry_after, get_redirect_url, is_xml
    from .version import Version

    log = logging.getLogger(__name__)

    def close_connections():
        CachingProtocol.clear_cache()

    class BaseProtocol:
        """Base class for Protocol which implements the bare essentials."""

        # The maximum number of sessions (== TCP connections, see below) we will open to this service endpoint. Keep this
        # low unless you have an agreement with the Exchange admin on the receiving end to hammer the server and
        # rate-limiting policies have been disabled for the connecting user. Changing this setting only makes sense if
        # you are using threads to run multiple concurrent workers in this process.
        SESSION_POOLSIZE = 1
        # We want only 1 TCP connection per Session object. We may have lots of different credentials hitting the server and
        # each credential needs its own session (NTLM auth will only send credentials once and then secure the connection,
        # so a connection can only handle requests for one credential). Having multiple connections per Session could
        # quickly exhaust the maximum number of concurrent connections the Exchange server allows from one client.
        CONNECTIONS_PER_SESSION = 1
        # The number of times a session may be reused before creating a new session object. 'None' means "infinite".
        # Discarding sessions after a certain number of usages may limit memory leaks in the Session object.
        MAX_SESSION_USAGE_COUNT = None
        # Timeout for HTTP requests
        TIMEOUT = 120
        RETRY_WAIT = 10  # Seconds to wait before retry on connection errors

        # The adapter class to use for HTTP requests. Override this if you need e.g. proxy support or specific TLS versions
        HTTP_ADAPTER_CLS = requests.adapters.HTTPAdapter

        # The User-Agent header to use for HTTP requests. Override this to set an app-specific one
        USERAGENT = None

        def __init__(self, config):
            self.config = config

            self._session_pool_size = 0
            self._session_pool_maxsize = config.max_connections or self.SESSION_POOLSIZE

            # Try to behave nicely with the remote server. We want to keep the connection open between requests.
            # We also want to re-use sessions, to avoid the NTLM auth handshake on every request. We must know the
            # authentication method to create sessions.
            self._session_pool = LifoQueue()
            self._session_pool_lock = Lock()

        @property
        def service_endpoint(self):
            return self.config.service_endpoint

        @abc.abstractmethod
        def get_auth_type(self):
            """Autodetect authentication type"""

        @property
        def auth_type(self):
            # Autodetect authentication type if necessary
            if self.config.auth_type is None:
                self.config.auth_type = self.get_auth_type()
            return self.config.auth_type

        @property
        def credentials(self):
            return self.config.credentials

        @credentials.setter
        def credentials(self, value):
            # We are updating credentials, but that doesn't automatically propagate to the session objects. The simplest
            # solution is to just kill the sessions in the pool.
            with self._session_pool_lock:
                self.config._credentials = value
                self.close()

        @property
        def max_connections(self):
            return self._session_pool_maxsize

        @max_connections.setter
        def max_connections(self, value):
            with self._session_pool_lock:
                self._session_pool_maxsize = value or self.SESSION_POOLSIZE

        @property
        def retry_policy(self):
            return self.config.retry_policy

        @property
        def server(self):
            return self.config.server

        def __getstate__(self):
            # The session pool and lock cannot be pickled
            state = self.__dict__.copy()
            del state["_session_pool"]
            del state["_session_pool_lock"]
            return state

        def __setstate__(self, state):
            # Restore the session pool and lock
            self.__dict__.update(state)
            self._session_pool = LifoQueue()
            self._session_pool_lock = Lock()

        def __del__(self):
            # pylint: disable=bare-except
            try:
                self.close()
            except Exception:  # nosec
                # __del__ should never fail
                pass

        def close(self):
            log.debug("Server %s: Closing sessions", self.server)
            while True:
                try:
                    session = self._session_pool.get(block=False)
                    self.close_session(session)
                    self._session_pool_size -= 1
                except Empty:
                    break

        @classmethod
        def get_adapter(cls):
            # We want just one connection per session. No retries, since we wrap all requests in our own retry handler
            return cls.HTTP_ADAPTER_CLS(
                pool_block=True,
                pool_connections=cls.CONNECTIONS_PER_SESSION,
                pool_maxsize=cls.CONNECTIONS_PER_SESSION,
                max_retries=0,
            )

        @property
        def session_pool_size(self):
            return self._session_pool_size

        def increase_poolsize(self):
            """Increases the session pool size. We increase by one session per call."""
            # Create a single session and insert it into the pool. We need to protect this with a lock while we are changing
            # the pool size variable, to avoid race conditions. We must not exceed the pool size limit.
            if self._session_pool_size >= self._session_pool_maxsize:
                raise SessionPoolMaxSizeReached("Session pool size cannot be increased further")
            with self._session_pool_lock:
                if self._session_pool_size >= self._session_pool_maxsize:
                    log.debug("Session pool size was increased in another thread")
                    return
                log.debug(
                    "Server %s: Increasing session pool size from %s to %s",
                    self.server,
                    self._session_pool_size,
                    self._session_pool_size + 1,
                )
                self._session_pool.put(self.create_session(), block=False)
                self._session_pool_size += 1

        def decrease_poolsize(self):
            """Decreases the session pool size in response to error messages from the server requesting to rate-limit
            requests. We decrease by one session per call.
            """
            # Take a single session from the pool and discard it. We need to protect this with a lock while we are changing
            # the pool size variable, to avoid race conditions. We must keep at least one session in the pool.
            if self._session_pool_size <= 1:
                raise SessionPoolMinSizeReached("Session pool size cannot be decreased further")
            with self._session_pool_lock:
                if self._session_pool_size <= 1:
                    log.debug("Session pool size was decreased in another thread")
                    return
                log.warning(
                    "Server %s: Decreasing session pool size from %s to %s",
                    self.server,
                    self._session_pool_size,
                    self._session_pool_size - 1,
                )
                session = self.get_session()
                self.close_session(session)
                self._session_pool_size -= 1

        def get_session(self):
            # Try to get a session from the queue. If the queue is empty, try to add one more session to the queue. If the
            # queue is already at its max, wait until a session becomes available.
            _timeout = 60  # Rate-limit messages about session starvation
            try:
                session = self._session_pool.get(block=False)
                log.debug("Server %s: Got session immediately", self.server)
            except Empty:
                with suppress(SessionPoolMaxSizeReached):
                    self.increase_poolsize()
                while True:
                    try:
                        log.debug("Server %s: Waiting for session", self.server)
                        session = self._session_pool.get(timeout=_timeout)
                        break
                    except Empty:
                        # This is normal when we have many worker threads starving for available sessions
                        log.debug("Server %s: No sessions available for %s seconds", self.server, _timeout)
            log.debug("Server %s: Got session %s", self.server, session.session_id)
            session.usage_count += 1
            return session

        def release_session(self, session):
            # This should never fail, as we don't have more sessions than the queue contains
            log.debug("Server %s: Releasing session %s", self.server, session.session_id)
            if self.MAX_SESSION_USAGE_COUNT and session.usage_count >= self.MAX_SESSION_USAGE_COUNT:
                log.debug("Server %s: session %s usage exceeded limit. Discarding", self.server, session.session_id)
                session = self.renew_session(session)
            self._session_pool.put(session, block=False)

        def close_session(self, session):
            if isinstance(self.credentials, BaseOAuth2Credentials) and isinstance(
                self.credentials.client, BackendApplicationClient
            ):
                # Reset access token
                with self.credentials.lock:
                    self.credentials.access_token = None
            session.close()
            del session

        def retire_session(self, session):
            # The session is useless. Close it completely and place a fresh session in the pool
            log.debug("Server %s: Retiring session %s", self.server, session.session_id)
            self.close_session(session)
            self.release_session(self.create_session())

        def renew_session(self, session):
            # The session is useless. Close it completely and place a fresh session in the pool
            log.debug("Server %s: Renewing session %s", self.server, session.session_id)
            self.close_session(session)
            return self.create_session()

        def refresh_credentials(self, session):
            # Credentials need to be refreshed, probably due to an OAuth
            # access token expiring. If we've gotten here, it's because the
            # application didn't provide an OAuth client secret, so we can't
            # handle token refreshing for it.
            with self.credentials.lock:
                if self.credentials.sig() == session.credentials_sig:
                    # Credentials have not been refreshed by another thread:
                    # they're the same as the session was created with. If
                    # this isn't the case, we can just go ahead with a new
                    # session using the already-updated credentials.
                    self.credentials.refresh(session=session)
            return self.renew_session(session)

        def create_session(self):
            if self.credentials is None:
                if self.auth_type in CREDENTIALS_REQUIRED:
                    raise ValueError(f"Auth type {self.auth_type!r} requires credentials")
                session = self.raw_session(self.service_endpoint)
                session.auth = get_auth_instance(auth_type=self.auth_type)
            else:
                if isinstance(self.credentials, BaseOAuth2Credentials):
                    with self.credentials.lock:
                        session = self.create_oauth2_session()
                        # Keep track of the credentials used to create this session. If and when we need to renew
                        # credentials (for example, refreshing an OAuth access token), this lets us easily determine whether
                        # the credentials have already been refreshed in another thread by the time this session tries.
                        session.credentials_sig = self.credentials.sig()
                else:
                    if self.auth_type == NTLM and self.credentials.type == self.credentials.EMAIL:
                        username = "\\" + self.credentials.username
                    else:
                        username = self.credentials.username
                    session = self.raw_session(self.service_endpoint)
                    session.auth = get_auth_instance(
                        auth_type=self.auth_type, username=username, password=self.credentials.password
                    )

            # Add some extra info
            session.session_id = random.randint(10000, 99999)  # Used for debugging messages in services
            session.usage_count = 0
            log.debug("Server %s: Created session %s", self.server, session.session_id)
            return session

        def create_oauth2_session(self):
            session = self.raw_session(
                self.service_endpoint,
                oauth2_client=self.credentials.client,
                oauth2_session_params=self.credentials.session_params(),
                oauth2_token_endpoint=self.credentials.token_url,
            )
            if not session.token:
                # Fetch the token explicitly -- it doesn't occur implicitly
                token = session.fetch_token(
                    token_url=self.credentials.token_url,
                    client_id=self.credentials.client_id,
                    client_secret=self.credentials.client_secret,
                    scope=self.credentials.scope,
                    timeout=self.TIMEOUT,
                    **self.credentials.token_params(),
                )
                # Allow the credentials object to update its copy of the new token, and give the application an opportunity
                # to cache it.
                self.credentials.on_token_auto_refreshed(token)
            session.auth = get_auth_instance(auth_type=OAUTH2, client=self.credentials.client)

            return session

        @classmethod
        def raw_session(cls, prefix, oauth2_client=None, oauth2_session_params=None, oauth2_token_endpoint=None):
            if oauth2_client:
                session = OAuth2Session(client=oauth2_client, **(oauth2_session_params or {}))
            else:
                session = requests.sessions.Session()
            session.headers.update(DEFAULT_HEADERS)
            session.headers["User-Agent"] = cls.USERAGENT
            session.mount(prefix, adapter=cls.get_adapter())
            if oauth2_token_endpoint:
                session.mount(oauth2_token_endpoint, adapter=cls.get_adapter())
            return session

        def __repr__(self):
            return self.__class__.__name__ + repr((self.service_endpoint, self.credentials, self.auth_type))

    class CachingProtocol(type):
        """A metaclass for Protocol that caches Protocol instances based on a server+username key."""

        _protocol_cache = {}
        _protocol_cache_lock = Lock()

        def __call__(cls, *args, **kwargs):
            # Cache Protocol instances that point to the same endpoint and use the same credentials. This ensures that we
            # re-use thread and connection pools etc. instead of flooding the remote server. This is a modified Singleton
            # pattern.
            #
            # We ignore auth_type from kwargs in the cache key. We trust caller to supply the correct auth_type - otherwise
            # __init__ will guess the correct auth type.
            config = kwargs["config"]
            from .configuration import Configuration

            if not isinstance(config, Configuration):
                raise InvalidTypeError("config", config, Configuration)
            if not config.service_endpoint:
                raise AttributeError("'config.service_endpoint' must be set")
            _protocol_cache_key = cls._cache_key(config)

            try:
                protocol, _ = cls._protocol_cache[_protocol_cache_key]
            except KeyError:
                pass
            else:
                if isinstance(protocol, Exception):
                    # The input data leads to a TransportError. Re-throw
                    raise protocol
                return protocol

            # Acquire lock to guard against multiple threads competing to cache information. Having a per-server lock is
            # probably overkill, although it would reduce lock contention.
            log.debug("Waiting for _protocol_cache_lock")
            with cls._protocol_cache_lock:
                try:
                    protocol, _ = cls._protocol_cache[_protocol_cache_key]
                except KeyError:
                    pass
                else:
                    if isinstance(protocol, Exception):
                        # We already tried this combination, possibly in a different competing thread, but the input
                        # data leads to a TransportError.
                        raise protocol
                    return protocol

                log.debug("Protocol __call__ cache miss. Adding key '%s'", str(_protocol_cache_key))
                try:
                    protocol = super().__call__(*args, **kwargs)
                except TransportError as e:
                    # This can happen if, for example, autodiscover supplies us with a bogus EWS endpoint
                    log.warning("Failed to create cached protocol with key %s: %s", _protocol_cache_key, e)
                    cls._protocol_cache[_protocol_cache_key] = e, datetime.datetime.now()
                    raise e
                cls._protocol_cache[_protocol_cache_key] = protocol, datetime.datetime.now()
            return protocol

        @staticmethod
        def _cache_key(config):
            # We may be using multiple different credentials for the same service endpoint. This key combination should be
            # safe.
            return config.service_endpoint, config.credentials

        def __getitem__(cls, config):
            return cls._protocol_cache[cls._cache_key(config)]

        def __delitem__(cls, config):
            del cls._protocol_cache[cls._cache_key(config)]

        @classmethod
        def clear_cache(mcs):
            with mcs._protocol_cache_lock:
                for key, (protocol, _) in mcs._protocol_cache.items():
                    if isinstance(protocol, Exception):
                        continue
                    service_endpoint = key[0]
                    log.debug("Service endpoint '%s': Closing sessions", service_endpoint)
                    with protocol._session_pool_lock:
                        protocol.close()
                mcs._protocol_cache.clear()

    class Protocol(BaseProtocol, metaclass=CachingProtocol):
        """A class to handle all the low-level communication with an Exchange server. Contains a session pool, knows how to
        negotiate the authentication type of the server, refresh credentials, etc. Also contains methods for calling EWS
        services that are not tied to an account.
        """

        def __init__(self, *args, **kwargs):
            super().__init__(*args, **kwargs)
            self._version_lock = Lock()
            self.api_version_hint = None

        def get_auth_type(self):
            # Autodetect authentication type. We also set 'self.api_version_hint' here.
            return get_service_authtype(protocol=self)

        @property
        def version(self):
            # Make sure only one thread does the guessing.
            if not self.config.version or not self.config.version.build:
                log.debug("Waiting for _version_lock")
                with self._version_lock:
                    if not self.config.version or not self.config.version.build:
                        # Version.guess() needs auth objects and a working session pool
                        self.config.version = Version.guess(self, api_version_hint=self.api_version_hint)
            return self.config.version

        def get_timezones(self, timezones=None, return_full_timezone_data=False):
            """Get timezone definitions from the server.

            :param timezones: A list of EWSDateTime instances. If None, fetches all timezones from server
              (Default value = None)
            :param return_full_timezone_data: If true, also returns periods and transitions (Default value = False)

            :return: A generator of TimeZoneDefinition objects
            """
            return GetServerTimeZones(protocol=self).call(
                timezones=timezones, return_full_timezone_data=return_full_timezone_data
            )

        def get_free_busy_info(self, accounts, start, end, merged_free_busy_interval=30, requested_view="DetailedMerged"):
            """Return free/busy information for a list of accounts.

            :param accounts: A list of (account, attendee_type, exclude_conflicts) tuples, where account is either an
              Account object or a string, attendee_type is a MailboxData.attendee_type choice, and exclude_conflicts is a
              boolean.
            :param start: The start datetime of the request
            :param end: The end datetime of the request
            :param merged_free_busy_interval: The interval, in minutes, of merged free/busy information (Default value = 30)
            :param requested_view: The type of information returned. Possible values are defined in the
              FreeBusyViewOptions.requested_view choices. (Default value = 'DetailedMerged')

            :return: A generator of FreeBusyView objects
            """
            from .account import Account

            tz_definition = list(self.get_timezones(timezones=[start.tzinfo], return_full_timezone_data=True))[0]
            return GetUserAvailability(self).call(
                tzinfo=start.tzinfo,
                mailbox_data=[
                    MailboxData(
                        email=account.primary_smtp_address if isinstance(account, Account) else account,
                        attendee_type=attendee_type,
                        exclude_conflicts=exclude_conflicts,
                    )
                    for account, attendee_type, exclude_conflicts in accounts
                ],
                timezone=TimeZone.from_server_timezone(tz_definition=tz_definition, for_year=start.year),
                free_busy_view_options=FreeBusyViewOptions(
                    time_window=TimeWindow(start=start, end=end),
                    merged_free_busy_interval=merged_free_busy_interval,
                    requested_view=requested_view,
                ),
            )

        def get_roomlists(self):
            return GetRoomLists(protocol=self).call()

        def get_rooms(self, roomlist):
            return GetRooms(protocol=self).call(room_list=RoomList(email_address=roomlist))

        def resolve_names(self, names, parent_folders=None, return_full_contact_data=False, search_scope=None, shape=None):
            """Resolve accounts on the server using partial account data, e.g. an email address or initials.

            :param names: A list of identifiers to query
            :param parent_folders: A list of contact folders to search in
            :param return_full_contact_data: If True, returns full contact data (Default value = False)
            :param search_scope: The scope to perform the search. Must be one of SEARCH_SCOPE_CHOICES (Default value = None)
            :param shape: (Default value = None)

            :return: A list of Mailbox items or, if return_full_contact_data is True, tuples of (Mailbox, Contact) items
            """
            return list(
                ResolveNames(protocol=self).call(
                    unresolved_entries=names,
                    parent_folders=parent_folders,
                    return_full_contact_data=return_full_contact_data,
                    search_scope=search_scope,
                    contact_data_shape=shape,
                )
            )

        def expand_dl(self, distribution_list):
            """Expand distribution list into its members.

            :param distribution_list: SMTP address of the distribution list to expand, or a DLMailbox representing the list

            :return: List of Mailbox items that are members of the distribution list
            """
            if isinstance(distribution_list, str):
                distribution_list = DLMailbox(email_address=distribution_list, mailbox_type="PublicDL")
            return list(ExpandDL(protocol=self).call(distribution_list=distribution_list))

        def get_searchable_mailboxes(self, search_filter=None, expand_group_membership=False):
            """Call the GetSearchableMailboxes service to get mailboxes that can be searched.

            This method is only available to users who have been assigned the Discovery Management RBAC role. See
            https://docs.microsoft.com/en-us/exchange/permissions-exo/permissions-exo

            :param search_filter: If set, must be a single email alias (Default value = None)
            :param expand_group_membership: If True, returned distribution lists are expanded (Default value = False)

            :return: a list of SearchableMailbox, FailedMailbox or Exception instances
            """
            return list(
                GetSearchableMailboxes(protocol=self).call(
                    search_filter=search_filter,
                    expand_group_membership=expand_group_membership,
                )
            )

        def convert_ids(self, ids, destination_format):
            """Convert item and folder IDs between multiple formats.

            :param ids: a list of AlternateId, AlternatePublicFolderId or AlternatePublicFolderItemId instances
            :param destination_format: A string

            :return: a generator of AlternateId, AlternatePublicFolderId or AlternatePublicFolderItemId instances
            """
            return ConvertId(protocol=self).call(items=ids, destination_format=destination_format)

        def dummy_xml(self):
            # Generate a minimal, valid EWS request
            svc = ConvertId(protocol=self)
            return svc.wrap(
                content=svc.get_payload(
                    items=[AlternateId(id="DUMMY", format=EWS_ID, mailbox="DUMMY")],
                    destination_format=ENTRY_ID,
                ),
                api_version=self.api_version_hint,
            )

        def __getstate__(self):
            # The lock cannot be pickled
            state = super().__getstate__()
            del state["_version_lock"]
            return state

        def __setstate__(self, state):
            # Restore the lock
            super().__setstate__(state)
            self._version_lock = Lock()

        def __str__(self):
            # Don't trigger version guessing here just for the sake of printing
            if self.config.version:
                fullname, api_version, build = self.version.fullname, self.version.api_version, self.version.build
            else:
                fullname, api_version, build = "[unknown]", "[unknown]", "[unknown]"

            return f"""\
    EWS url: {self.service_endpoint}
    Product name: {fullname}
    EWS API version: {api_version}
    Build number: {build}
    EWS auth: {self.auth_type}"""

    class NoVerifyHTTPAdapter(requests.adapters.HTTPAdapter):
        """An HTTP adapter that ignores TLS validation errors. Use at own risk."""

        def cert_verify(self, conn, url, verify, cert):
            # pylint: disable=unused-argument
            # We're overriding a method, so we have to keep the signature
            super().cert_verify(conn=conn, url=url, verify=False, cert=cert)

        def get_connection_with_tls_context(self, request, verify, proxies=None, cert=None):
            # pylint: disable=unused-argument
            # Required for requests >= 2.32.3
            # See: https://github.com/psf/requests/pull/6710
            return super().get_connection_with_tls_context(request=request, verify=False, proxies=proxies, cert=cert)

    class TLSClientAuth(requests.adapters.HTTPAdapter):
        """An HTTP adapter that implements Certificate Based Authentication (CBA)."""

        cert_file = None

        def init_poolmanager(self, *args, **kwargs):
            kwargs["cert_file"] = self.cert_file
            return super().init_poolmanager(*args, **kwargs)

    class RetryPolicy(metaclass=abc.ABCMeta):
        """Stores retry logic used when faced with errors from the server."""

        @property
        @abc.abstractmethod
        def fail_fast(self):
            """Used to choose the error handling policy. When True, a fault-tolerant policy is used. False, a fail-fast
            policy is used."""

        @property
        @abc.abstractmethod
        def back_off_until(self):
            """Return a datetime to back off until"""

        @back_off_until.setter
        @abc.abstractmethod
        def back_off_until(self, value):
            """Setter for back off values"""

        @abc.abstractmethod
        def back_off(self, seconds):
            """Set a new back off until value"""

        def raise_response_errors(self, response):
            if response.status_code == 200:
                # Response is OK
                return
            if response.status_code == 500 and response.content and is_xml(response.content):
                # Some genius at Microsoft thinks it's OK to send a valid SOAP response as an HTTP 500
                log.debug("Got status code %s but trying to parse content anyway", response.status_code)
                return
            cas_error = response.headers.get("X-CasErrorCode")
            if cas_error:
                if cas_error.startswith("CAS error:"):
                    # Remove unnecessary text
                    cas_error = cas_error.split(":", 1)[1].strip()
                raise CASError(cas_error=cas_error, response=response)
            if response.status_code == 500 and (
                b"The specified server version is invalid" in response.content
                or b"ErrorInvalidSchemaVersionForMailboxVersion" in response.content
            ):
                # Another way of communicating invalid schema versions
                raise ErrorInvalidSchemaVersionForMailboxVersion("Invalid server version")
            if response.headers.get("connection") == "close":
                # Connection closed. OK to retry.
                raise ErrorServerBusy("Caused by closed connection")
            if (
                response.status_code == 302
                and response.headers.get("location", "").lower()
                == "/ews/genericerrorpage.htm?aspxerrorpath=/ews/exchange.asmx"
            ):
                # Redirect to genericerrorpage.htm is ridiculous behaviour for random outages. OK to retry.
                #
                # Redirect to '/internalsite/internalerror.asp' or '/internalsite/initparams.aspx' is caused by e.g. TLS
                # certificate f*ckups on the Exchange server. We should not retry those.
                raise ErrorInternalServerTransientError(f"Caused by HTTP 302 redirect to {response.headers['location']}")
            if response.status_code in (301, 302):
                try:
                    redirect_url = get_redirect_url(response=response, allow_relative=False)
                except RelativeRedirect as e:
                    log.debug("Redirect not allowed but we were relative redirected (%s -> %s)", response.url, e.value)
                    raise RedirectError(url=e.value)
                log.debug("Redirect not allowed but we were redirected ( (%s -> %s)", response.url, redirect_url)
                raise RedirectError(url=redirect_url)
            if b"The referenced account is currently locked out" in response.content:
                raise UnauthorizedError("The referenced account is currently locked out")
            if response.status_code == 401 and self.fail_fast:
                # This is a login failure
                raise UnauthorizedError(f"Invalid credentials for {response.url}")
            if response.status_code == 401:
                # EWS sometimes throws 401's when it wants us to throttle connections. OK to retry.
                raise ErrorServerBusy("Caused by HTTP 401 response")
            if response.status_code == 500 and b"Server Error in '/EWS' Application" in response.content:
                # "Server Error in '/EWS' Application" has been seen in highly concurrent settings. OK to retry.
                raise ErrorInternalServerTransientError("Caused by \"Server Error in 'EWS' Application\"")
            if response.status_code == 503:
                # Internal server error. OK to retry.
                raise ErrorInternalServerTransientError("Caused by HTTP 503 response")
            # This could be anything. Let higher layers handle this
            raise MalformedResponseError(
                f"Unknown failure in response. Code: {response.status_code} headers: {response.headers} "
                f"content: {response.text}"
            )

    class FailFast(RetryPolicy):
        """Fail immediately on server errors."""

        @property
        def fail_fast(self):
            return True

        @property
        def back_off_until(self):
            return None

        def back_off(self, seconds):
            raise ValueError("Cannot back off with fail-fast policy")

    class FaultTolerance(RetryPolicy):
        """Enables fault-tolerant error handling. Tells internal methods to do an exponential back off when requests start
        failing, and wait up to max_wait seconds before failing.
        """

        # Back off 60 seconds if we didn't get an explicit suggested value
        DEFAULT_BACKOFF = 60

        def __init__(self, max_wait=3600):
            self.max_wait = max_wait
            self._back_off_until = None
            self._back_off_lock = Lock()

        def __getstate__(self):
            # Locks cannot be pickled
            state = self.__dict__.copy()
            del state["_back_off_lock"]
            return state

        def __setstate__(self, state):
            # Restore the lock
            self.__dict__.update(state)
            self._back_off_lock = Lock()

        @property
        def fail_fast(self):
            return False

        @property
        def back_off_until(self):
            """Return the back off value as a datetime. Reset the current back off value if it has expired."""
            if self._back_off_until is None:
                return None
            with self._back_off_lock:
                if self._back_off_until is None:
                    return None
                if self._back_off_until < datetime.datetime.now():
                    self._back_off_until = None  # The back off value has expired. Reset
                    return None
                return self._back_off_until

        @back_off_until.setter
        def back_off_until(self, value):
            with self._back_off_lock:
                self._back_off_until = value

        def back_off(self, seconds):
            if seconds is None:
                seconds = self.DEFAULT_BACKOFF
            if seconds > self.max_wait:
                # We lost patience. Session is cleaned up in outer loop
                raise RateLimitError("Max timeout reached", wait=seconds)
            value = datetime.datetime.now() + datetime.timedelta(seconds=seconds)
            with self._back_off_lock:
                self._back_off_until = value

        def raise_response_errors(self, response):
            try:
                return super().raise_response_errors(response)
            except (ErrorInternalServerTransientError, ErrorServerBusy) as e:
                # Pass on the retry header value
                retry_after = _get_retry_after(response)
                if retry_after:
                    raise ErrorServerBusy(e.args[0], back_off=retry_after)
                raise

## Functions

`def close_connections()`
  Expand source code

      def close_connections():
          CachingProtocol.clear_cache()

## Classes

`class BaseProtocol (config)`

  Base class for Protocol which implements the bare essentials.

  Expand source code

      class BaseProtocol:
          """Base class for Protocol which implements the bare essentials."""

          # The maximum number of sessions (== TCP connections, see below) we will open to this service endpoint. Keep this
          # low unless you have an agreement with the Exchange admin on the receiving end to hammer the server and
          # rate-limiting policies have been disabled for the connecting user. Changing this setting only makes sense if
          # you are using threads to run multiple concurrent workers in this process.
          SESSION_POOLSIZE = 1
          # We want only 1 TCP connection per Session object. We may have lots of different credentials hitting the server and
          # each credential needs its own session (NTLM auth will only send credentials once and then secure the connection,
          # so a connection can only handle requests for one credential). Having multiple connections per Session could
          # quickly exhaust the maximum number of concurrent connections the Exchange server allows from one client.
          CONNECTIONS_PER_SESSION = 1
          # The number of times a session may be reused before creating a new session object. 'None' means "infinite".
          # Discarding sessions after a certain number of usages may limit memory leaks in the Session object.
          MAX_SESSION_USAGE_COUNT = None
          # Timeout for HTTP requests
          TIMEOUT = 120
          RETRY_WAIT = 10  # Seconds to wait before retry on connection errors

          # The adapter class to use for HTTP requests. Override this if you need e.g. proxy support or specific TLS versions
          HTTP_ADAPTER_CLS = requests.adapters.HTTPAdapter

          # The User-Agent header to use for HTTP requests. Override this to set an app-specific one
          USERAGENT = None

          def __init__(self, config):
              self.config = config

              self._session_pool_size = 0
              self._session_pool_maxsize = config.max_connections or self.SESSION_POOLSIZE

              # Try to behave nicely with the remote server. We want to keep the connection open between requests.
              # We also want to re-use sessions, to avoid the NTLM auth handshake on every request. We must know the
              # authentication method to create sessions.
              self._session_pool = LifoQueue()
              self._session_pool_lock = Lock()

          @property
          def service_endpoint(self):
              return self.config.service_endpoint

          @abc.abstractmethod
          def get_auth_type(self):
              """Autodetect authentication type"""

          @property
          def auth_type(self):
              # Autodetect authentication type if necessary
              if self.config.auth_type is None:
                  self.config.auth_type = self.get_auth_type()
              return self.config.auth_type

          @property
          def credentials(self):
              return self.config.credentials

          @credentials.setter
          def credentials(self, value):
              # We are updating credentials, but that doesn't automatically propagate to the session objects. The simplest
              # solution is to just kill the sessions in the pool.
              with self._session_pool_lock:
                  self.config._credentials = value
                  self.close()

          @property
          def max_connections(self):
              return self._session_pool_maxsize

          @max_connections.setter
          def max_connections(self, value):
              with self._session_pool_lock:
                  self._session_pool_maxsize = value or self.SESSION_POOLSIZE

          @property
          def retry_policy(self):
              return self.config.retry_policy

          @property
          def server(self):
              return self.config.server

          def __getstate__(self):
              # The session pool and lock cannot be pickled
              state = self.__dict__.copy()
              del state["_session_pool"]
              del state["_session_pool_lock"]
              return state

          def __setstate__(self, state):
              # Restore the session pool and lock
              self.__dict__.update(state)
              self._session_pool = LifoQueue()
              self._session_pool_lock = Lock()

          def __del__(self):
              # pylint: disable=bare-except
              try:
                  self.close()
              except Exception:  # nosec
                  # __del__ should never fail
                  pass

          def close(self):
              log.debug("Server %s: Closing sessions", self.server)
              while True:
                  try:
                      session = self._session_pool.get(block=False)
                      self.close_session(session)
                      self._session_pool_size -= 1
                  except Empty:
                      break

          @classmethod
          def get_adapter(cls):
              # We want just one connection per session. No retries, since we wrap all requests in our own retry handler
              return cls.HTTP_ADAPTER_CLS(
                  pool_block=True,
                  pool_connections=cls.CONNECTIONS_PER_SESSION,
                  pool_maxsize=cls.CONNECTIONS_PER_SESSION,
                  max_retries=0,
              )

          @property
          def session_pool_size(self):
              return self._session_pool_size

          def increase_poolsize(self):
              """Increases the session pool size. We increase by one session per call."""
              # Create a single session and insert it into the pool. We need to protect this with a lock while we are changing
              # the pool size variable, to avoid race conditions. We must not exceed the pool size limit.
              if self._session_pool_size >= self._session_pool_maxsize:
                  raise SessionPoolMaxSizeReached("Session pool size cannot be increased further")
              with self._session_pool_lock:
                  if self._session_pool_size >= self._session_pool_maxsize:
                      log.debug("Session pool size was increased in another thread")
                      return
                  log.debug(
                      "Server %s: Increasing session pool size from %s to %s",
                      self.server,
                      self._session_pool_size,
                      self._session_pool_size + 1,
                  )
                  self._session_pool.put(self.create_session(), block=False)
                  self._session_pool_size += 1

          def decrease_poolsize(self):
              """Decreases the session pool size in response to error messages from the server requesting to rate-limit
              requests. We decrease by one session per call.
              """
              # Take a single session from the pool and discard it. We need to protect this with a lock while we are changing
              # the pool size variable, to avoid race conditions. We must keep at least one session in the pool.
              if self._session_pool_size <= 1:
                  raise SessionPoolMinSizeReached("Session pool size cannot be decreased further")
              with self._session_pool_lock:
                  if self._session_pool_size <= 1:
                      log.debug("Session pool size was decreased in another thread")
                      return
                  log.warning(
                      "Server %s: Decreasing session pool size from %s to %s",
                      self.server,
                      self._session_pool_size,
                      self._session_pool_size - 1,
                  )
                  session = self.get_session()
                  self.close_session(session)
                  self._session_pool_size -= 1

          def get_session(self):
              # Try to get a session from the queue. If the queue is empty, try to add one more session to the queue. If the
              # queue is already at its max, wait until a session becomes available.
              _timeout = 60  # Rate-limit messages about session starvation
              try:
                  session = self._session_pool.get(block=False)
                  log.debug("Server %s: Got session immediately", self.server)
              except Empty:
                  with suppress(SessionPoolMaxSizeReached):
                      self.increase_poolsize()
                  while True:
                      try:
                          log.debug("Server %s: Waiting for session", self.server)
                          session = self._session_pool.get(timeout=_timeout)
                          break
                      except Empty:
                          # This is normal when we have many worker threads starving for available sessions
                          log.debug("Server %s: No sessions available for %s seconds", self.server, _timeout)
              log.debug("Server %s: Got session %s", self.server, session.session_id)
              session.usage_count += 1
              return session

          def release_session(self, session):
              # This should never fail, as we don't have more sessions than the queue contains
              log.debug("Server %s: Releasing session %s", self.server, session.session_id)
              if self.MAX_SESSION_USAGE_COUNT and session.usage_count >= self.MAX_SESSION_USAGE_COUNT:
                  log.debug("Server %s: session %s usage exceeded limit. Discarding", self.server, session.session_id)
                  session = self.renew_session(session)
              self._session_pool.put(session, block=False)

          def close_session(self, session):
              if isinstance(self.credentials, BaseOAuth2Credentials) and isinstance(
                  self.credentials.client, BackendApplicationClient
              ):
                  # Reset access token
                  with self.credentials.lock:
                      self.credentials.access_token = None
              session.close()
              del session

          def retire_session(self, session):
              # The session is useless. Close it completely and place a fresh session in the pool
              log.debug("Server %s: Retiring session %s", self.server, session.session_id)
              self.close_session(session)
              self.release_session(self.create_session())

          def renew_session(self, session):
              # The session is useless. Close it completely and place a fresh session in the pool
              log.debug("Server %s: Renewing session %s", self.server, session.session_id)
              self.close_session(session)
              return self.create_session()

          def refresh_credentials(self, session):
              # Credentials need to be refreshed, probably due to an OAuth
              # access token expiring. If we've gotten here, it's because the
              # application didn't provide an OAuth client secret, so we can't
              # handle token refreshing for it.
              with self.credentials.lock:
                  if self.credentials.sig() == session.credentials_sig:
                      # Credentials have not been refreshed by another thread:
                      # they're the same as the session was created with. If
                      # this isn't the case, we can just go ahead with a new
                      # session using the already-updated credentials.
                      self.credentials.refresh(session=session)
              return self.renew_session(session)

          def create_session(self):
              if self.credentials is None:
                  if self.auth_type in CREDENTIALS_REQUIRED:
                      raise ValueError(f"Auth type {self.auth_type!r} requires credentials")
                  session = self.raw_session(self.service_endpoint)
                  session.auth = get_auth_instance(auth_type=self.auth_type)
              else:
                  if isinstance(self.credentials, BaseOAuth2Credentials):
                      with self.credentials.lock:
                          session = self.create_oauth2_session()
                          # Keep track of the credentials used to create this session. If and when we need to renew
                          # credentials (for example, refreshing an OAuth access token), this lets us easily determine whether
                          # the credentials have already been refreshed in another thread by the time this session tries.
                          session.credentials_sig = self.credentials.sig()
                  else:
                      if self.auth_type == NTLM and self.credentials.type == self.credentials.EMAIL:
                          username = "\\" + self.credentials.username
                      else:
                          username = self.credentials.username
                      session = self.raw_session(self.service_endpoint)
                      session.auth = get_auth_instance(
                          auth_type=self.auth_type, username=username, password=self.credentials.password
                      )

              # Add some extra info
              session.session_id = random.randint(10000, 99999)  # Used for debugging messages in services
              session.usage_count = 0
              log.debug("Server %s: Created session %s", self.server, session.session_id)
              return session

          def create_oauth2_session(self):
              session = self.raw_session(
                  self.service_endpoint,
                  oauth2_client=self.credentials.client,
                  oauth2_session_params=self.credentials.session_params(),
                  oauth2_token_endpoint=self.credentials.token_url,
              )
              if not session.token:
                  # Fetch the token explicitly -- it doesn't occur implicitly
                  token = session.fetch_token(
                      token_url=self.credentials.token_url,
                      client_id=self.credentials.client_id,
                      client_secret=self.credentials.client_secret,
                      scope=self.credentials.scope,
                      timeout=self.TIMEOUT,
                      **self.credentials.token_params(),
                  )
                  # Allow the credentials object to update its copy of the new token, and give the application an opportunity
                  # to cache it.
                  self.credentials.on_token_auto_refreshed(token)
              session.auth = get_auth_instance(auth_type=OAUTH2, client=self.credentials.client)

              return session

          @classmethod
          def raw_session(cls, prefix, oauth2_client=None, oauth2_session_params=None, oauth2_token_endpoint=None):
              if oauth2_client:
                  session = OAuth2Session(client=oauth2_client, **(oauth2_session_params or {}))
              else:
                  session = requests.sessions.Session()
              session.headers.update(DEFAULT_HEADERS)
              session.headers["User-Agent"] = cls.USERAGENT
              session.mount(prefix, adapter=cls.get_adapter())
              if oauth2_token_endpoint:
                  session.mount(oauth2_token_endpoint, adapter=cls.get_adapter())
              return session

          def __repr__(self):
              return self.__class__.__name__ + repr((self.service_endpoint, self.credentials, self.auth_type))

  ### Subclasses

  - AutodiscoverProtocol
  - Protocol

  ### Class variables

  `var CONNECTIONS_PER_SESSION`
  `var HTTP_ADAPTER_CLS`

    The built-in HTTP Adapter for urllib3.

    Provides a general-case interface for Requests sessions to contact HTTP and HTTPS urls by implementing the Transport Adapter interface. This class will usually be created by the :class:`Session <Session>` class under the covers.

    :param pool_connections: The number of urllib3 connection pools to cache. :param pool_maxsize: The maximum number of connections to save in the pool. :param max_retries: The maximum number of retries each connection should attempt. Note, this applies only to failed DNS lookups, socket connections and connection timeouts, never to requests where data has made it to the server. By default, Requests does not retry failed connections. If you need granular control over the conditions under which we retry a request, import urllib3's `Retry` class and pass that instead. :param pool_block: Whether the connection pool should block for connections.

    Usage::

    > > > import requests s = requests.Session() a = requests.adapters.HTTPAdapter(max_retries=3) s.mount('http://', a)

  `var MAX_SESSION_USAGE_COUNT`
  `var RETRY_WAIT`
  `var SESSION_POOLSIZE`
  `var TIMEOUT`
  `var USERAGENT`

  ### Static methods

  `def get_adapter()`
    Expand source code

        @classmethod
        def get_adapter(cls):
            # We want just one connection per session. No retries, since we wrap all requests in our own retry handler
            return cls.HTTP_ADAPTER_CLS(
                pool_block=True,
                pool_connections=cls.CONNECTIONS_PER_SESSION,
                pool_maxsize=cls.CONNECTIONS_PER_SESSION,
                max_retries=0,
            )

  `def raw_session(prefix, oauth2_client=None, oauth2_session_params=None, oauth2_token_endpoint=None)`
    Expand source code

        @classmethod
        def raw_session(cls, prefix, oauth2_client=None, oauth2_session_params=None, oauth2_token_endpoint=None):
            if oauth2_client:
                session = OAuth2Session(client=oauth2_client, **(oauth2_session_params or {}))
            else:
                session = requests.sessions.Session()
            session.headers.update(DEFAULT_HEADERS)
            session.headers["User-Agent"] = cls.USERAGENT
            session.mount(prefix, adapter=cls.get_adapter())
            if oauth2_token_endpoint:
                session.mount(oauth2_token_endpoint, adapter=cls.get_adapter())
            return session

  ### Instance variables

  `var auth_type`
    Expand source code

        @property
        def auth_type(self):
            # Autodetect authentication type if necessary
            if self.config.auth_type is None:
                self.config.auth_type = self.get_auth_type()
            return self.config.auth_type

  `var credentials`
    Expand source code

        @property
        def credentials(self):
            return self.config.credentials

  `var max_connections`
    Expand source code

        @property
        def max_connections(self):
            return self._session_pool_maxsize

  `var retry_policy`
    Expand source code

        @property
        def retry_policy(self):
            return self.config.retry_policy

  `var server`
    Expand source code

        @property
        def server(self):
            return self.config.server

  `var service_endpoint`
    Expand source code

        @property
        def service_endpoint(self):
            return self.config.service_endpoint

  `var session_pool_size`
    Expand source code

        @property
        def session_pool_size(self):
            return self._session_pool_size

  ### Methods

  `def close(self)`
    Expand source code

        def close(self):
            log.debug("Server %s: Closing sessions", self.server)
            while True:
                try:
                    session = self._session_pool.get(block=False)
                    self.close_session(session)
                    self._session_pool_size -= 1
                except Empty:
                    break

  `def close_session(self, session)`
    Expand source code

        def close_session(self, session):
            if isinstance(self.credentials, BaseOAuth2Credentials) and isinstance(
                self.credentials.client, BackendApplicationClient
            ):
                # Reset access token
                with self.credentials.lock:
                    self.credentials.access_token = None
            session.close()
            del session

  `def create_oauth2_session(self)`
    Expand source code

        def create_oauth2_session(self):
            session = self.raw_session(
                self.service_endpoint,
                oauth2_client=self.credentials.client,
                oauth2_session_params=self.credentials.session_params(),
                oauth2_token_endpoint=self.credentials.token_url,
            )
            if not session.token:
                # Fetch the token explicitly -- it doesn't occur implicitly
                token = session.fetch_token(
                    token_url=self.credentials.token_url,
                    client_id=self.credentials.client_id,
                    client_secret=self.credentials.client_secret,
                    scope=self.credentials.scope,
                    timeout=self.TIMEOUT,
                    **self.credentials.token_params(),
                )
                # Allow the credentials object to update its copy of the new token, and give the application an opportunity
                # to cache it.
                self.credentials.on_token_auto_refreshed(token)
            session.auth = get_auth_instance(auth_type=OAUTH2, client=self.credentials.client)

            return session

  `def create_session(self)`
    Expand source code

        def create_session(self):
            if self.credentials is None:
                if self.auth_type in CREDENTIALS_REQUIRED:
                    raise ValueError(f"Auth type {self.auth_type!r} requires credentials")
                session = self.raw_session(self.service_endpoint)
                session.auth = get_auth_instance(auth_type=self.auth_type)
            else:
                if isinstance(self.credentials, BaseOAuth2Credentials):
                    with self.credentials.lock:
                        session = self.create_oauth2_session()
                        # Keep track of the credentials used to create this session. If and when we need to renew
                        # credentials (for example, refreshing an OAuth access token), this lets us easily determine whether
                        # the credentials have already been refreshed in another thread by the time this session tries.
                        session.credentials_sig = self.credentials.sig()
                else:
                    if self.auth_type == NTLM and self.credentials.type == self.credentials.EMAIL:
                        username = "\\" + self.credentials.username
                    else:
                        username = self.credentials.username
                    session = self.raw_session(self.service_endpoint)
                    session.auth = get_auth_instance(
                        auth_type=self.auth_type, username=username, password=self.credentials.password
                    )

            # Add some extra info
            session.session_id = random.randint(10000, 99999)  # Used for debugging messages in services
            session.usage_count = 0
            log.debug("Server %s: Created session %s", self.server, session.session_id)
            return session

  `def decrease_poolsize(self)`

    Decreases the session pool size in response to error messages from the server requesting to rate-limit requests. We decrease by one session per call.

    Expand source code

        def decrease_poolsize(self):
            """Decreases the session pool size in response to error messages from the server requesting to rate-limit
            requests. We decrease by one session per call.
            """
            # Take a single session from the pool and discard it. We need to protect this with a lock while we are changing
            # the pool size variable, to avoid race conditions. We must keep at least one session in the pool.
            if self._session_pool_size <= 1:
                raise SessionPoolMinSizeReached("Session pool size cannot be decreased further")
            with self._session_pool_lock:
                if self._session_pool_size <= 1:
                    log.debug("Session pool size was decreased in another thread")
                    return
                log.warning(
                    "Server %s: Decreasing session pool size from %s to %s",
                    self.server,
                    self._session_pool_size,
                    self._session_pool_size - 1,
                )
                session = self.get_session()
                self.close_session(session)
                self._session_pool_size -= 1

  `def get_auth_type(self)`

    Autodetect authentication type

    Expand source code

        @abc.abstractmethod
        def get_auth_type(self):
            """Autodetect authentication type"""

  `def get_session(self)`
    Expand source code

        def get_session(self):
            # Try to get a session from the queue. If the queue is empty, try to add one more session to the queue. If the
            # queue is already at its max, wait until a session becomes available.
            _timeout = 60  # Rate-limit messages about session starvation
            try:
                session = self._session_pool.get(block=False)
                log.debug("Server %s: Got session immediately", self.server)
            except Empty:
                with suppress(SessionPoolMaxSizeReached):
                    self.increase_poolsize()
                while True:
                    try:
                        log.debug("Server %s: Waiting for session", self.server)
                        session = self._session_pool.get(timeout=_timeout)
                        break
                    except Empty:
                        # This is normal when we have many worker threads starving for available sessions
                        log.debug("Server %s: No sessions available for %s seconds", self.server, _timeout)
            log.debug("Server %s: Got session %s", self.server, session.session_id)
            session.usage_count += 1
            return session

  `def increase_poolsize(self)`

    Increases the session pool size. We increase by one session per call.

    Expand source code

        def increase_poolsize(self):
            """Increases the session pool size. We increase by one session per call."""
            # Create a single session and insert it into the pool. We need to protect this with a lock while we are changing
            # the pool size variable, to avoid race conditions. We must not exceed the pool size limit.
            if self._session_pool_size >= self._session_pool_maxsize:
                raise SessionPoolMaxSizeReached("Session pool size cannot be increased further")
            with self._session_pool_lock:
                if self._session_pool_size >= self._session_pool_maxsize:
                    log.debug("Session pool size was increased in another thread")
                    return
                log.debug(
                    "Server %s: Increasing session pool size from %s to %s",
                    self.server,
                    self._session_pool_size,
                    self._session_pool_size + 1,
                )
                self._session_pool.put(self.create_session(), block=False)
                self._session_pool_size += 1

  `def refresh_credentials(self, session)`
    Expand source code

        def refresh_credentials(self, session):
            # Credentials need to be refreshed, probably due to an OAuth
            # access token expiring. If we've gotten here, it's because the
            # application didn't provide an OAuth client secret, so we can't
            # handle token refreshing for it.
            with self.credentials.lock:
                if self.credentials.sig() == session.credentials_sig:
                    # Credentials have not been refreshed by another thread:
                    # they're the same as the session was created with. If
                    # this isn't the case, we can just go ahead with a new
                    # session using the already-updated credentials.
                    self.credentials.refresh(session=session)
            return self.renew_session(session)

  `def release_session(self, session)`
    Expand source code

        def release_session(self, session):
            # This should never fail, as we don't have more sessions than the queue contains
            log.debug("Server %s: Releasing session %s", self.server, session.session_id)
            if self.MAX_SESSION_USAGE_COUNT and session.usage_count >= self.MAX_SESSION_USAGE_COUNT:
                log.debug("Server %s: session %s usage exceeded limit. Discarding", self.server, session.session_id)
                session = self.renew_session(session)
            self._session_pool.put(session, block=False)

  `def renew_session(self, session)`
    Expand source code

        def renew_session(self, session):
            # The session is useless. Close it completely and place a fresh session in the pool
            log.debug("Server %s: Renewing session %s", self.server, session.session_id)
            self.close_session(session)
            return self.create_session()

  `def retire_session(self, session)`
    Expand source code

        def retire_session(self, session):
            # The session is useless. Close it completely and place a fresh session in the pool
            log.debug("Server %s: Retiring session %s", self.server, session.session_id)
            self.close_session(session)
            self.release_session(self.create_session())

`class CachingProtocol (*args, **kwargs)`

  A metaclass for Protocol that caches Protocol instances based on a server+username key.

  Expand source code

      class CachingProtocol(type):
          """A metaclass for Protocol that caches Protocol instances based on a server+username key."""

          _protocol_cache = {}
          _protocol_cache_lock = Lock()

          def __call__(cls, *args, **kwargs):
              # Cache Protocol instances that point to the same endpoint and use the same credentials. This ensures that we
              # re-use thread and connection pools etc. instead of flooding the remote server. This is a modified Singleton
              # pattern.
              #
              # We ignore auth_type from kwargs in the cache key. We trust caller to supply the correct auth_type - otherwise
              # __init__ will guess the correct auth type.
              config = kwargs["config"]
              from .configuration import Configuration

              if not isinstance(config, Configuration):
                  raise InvalidTypeError("config", config, Configuration)
              if not config.service_endpoint:
                  raise AttributeError("'config.service_endpoint' must be set")
              _protocol_cache_key = cls._cache_key(config)

              try:
                  protocol, _ = cls._protocol_cache[_protocol_cache_key]
              except KeyError:
                  pass
              else:
                  if isinstance(protocol, Exception):
                      # The input data leads to a TransportError. Re-throw
                      raise protocol
                  return protocol

              # Acquire lock to guard against multiple threads competing to cache information. Having a per-server lock is
              # probably overkill, although it would reduce lock contention.
              log.debug("Waiting for _protocol_cache_lock")
              with cls._protocol_cache_lock:
                  try:
                      protocol, _ = cls._protocol_cache[_protocol_cache_key]
                  except KeyError:
                      pass
                  else:
                      if isinstance(protocol, Exception):
                          # We already tried this combination, possibly in a different competing thread, but the input
                          # data leads to a TransportError.
                          raise protocol
                      return protocol

                  log.debug("Protocol __call__ cache miss. Adding key '%s'", str(_protocol_cache_key))
                  try:
                      protocol = super().__call__(*args, **kwargs)
                  except TransportError as e:
                      # This can happen if, for example, autodiscover supplies us with a bogus EWS endpoint
                      log.warning("Failed to create cached protocol with key %s: %s", _protocol_cache_key, e)
                      cls._protocol_cache[_protocol_cache_key] = e, datetime.datetime.now()
                      raise e
                  cls._protocol_cache[_protocol_cache_key] = protocol, datetime.datetime.now()
              return protocol

          @staticmethod
          def _cache_key(config):
              # We may be using multiple different credentials for the same service endpoint. This key combination should be
              # safe.
              return config.service_endpoint, config.credentials

          def __getitem__(cls, config):
              return cls._protocol_cache[cls._cache_key(config)]

          def __delitem__(cls, config):
              del cls._protocol_cache[cls._cache_key(config)]

          @classmethod
          def clear_cache(mcs):
              with mcs._protocol_cache_lock:
                  for key, (protocol, _) in mcs._protocol_cache.items():
                      if isinstance(protocol, Exception):
                          continue
                      service_endpoint = key[0]
                      log.debug("Service endpoint '%s': Closing sessions", service_endpoint)
                      with protocol._session_pool_lock:
                          protocol.close()
                  mcs._protocol_cache.clear()

  ### Ancestors

  - builtins.type

  ### Static methods

  `def clear_cache()`
    Expand source code

        @classmethod
        def clear_cache(mcs):
            with mcs._protocol_cache_lock:
                for key, (protocol, _) in mcs._protocol_cache.items():
                    if isinstance(protocol, Exception):
                        continue
                    service_endpoint = key[0]
                    log.debug("Service endpoint '%s': Closing sessions", service_endpoint)
                    with protocol._session_pool_lock:
                        protocol.close()
                mcs._protocol_cache.clear()

`class FailFast`

  Fail immediately on server errors.

  Expand source code

      class FailFast(RetryPolicy):
          """Fail immediately on server errors."""

          @property
          def fail_fast(self):
              return True

          @property
          def back_off_until(self):
              return None

          def back_off(self, seconds):
              raise ValueError("Cannot back off with fail-fast policy")

  ### Ancestors

  - RetryPolicy

  ### Inherited members

  - `RetryPolicy`:
    - `back_off`
    - `back_off_until`
    - `fail_fast`
`class FaultTolerance (max_wait=3600)`

  Enables fault-tolerant error handling. Tells internal methods to do an exponential back off when requests start failing, and wait up to max_wait seconds before failing.

  Expand source code

      class FaultTolerance(RetryPolicy):
          """Enables fault-tolerant error handling. Tells internal methods to do an exponential back off when requests start
          failing, and wait up to max_wait seconds before failing.
          """

          # Back off 60 seconds if we didn't get an explicit suggested value
          DEFAULT_BACKOFF = 60

          def __init__(self, max_wait=3600):
              self.max_wait = max_wait
              self._back_off_until = None
              self._back_off_lock = Lock()

          def __getstate__(self):
              # Locks cannot be pickled
              state = self.__dict__.copy()
              del state["_back_off_lock"]
              return state

          def __setstate__(self, state):
              # Restore the lock
              self.__dict__.update(state)
              self._back_off_lock = Lock()

          @property
          def fail_fast(self):
              return False

          @property
          def back_off_until(self):
              """Return the back off value as a datetime. Reset the current back off value if it has expired."""
              if self._back_off_until is None:
                  return None
              with self._back_off_lock:
                  if self._back_off_until is None:
                      return None
                  if self._back_off_until < datetime.datetime.now():
                      self._back_off_until = None  # The back off value has expired. Reset
                      return None
                  return self._back_off_until

          @back_off_until.setter
          def back_off_until(self, value):
              with self._back_off_lock:
                  self._back_off_until = value

          def back_off(self, seconds):
              if seconds is None:
                  seconds = self.DEFAULT_BACKOFF
              if seconds > self.max_wait:
                  # We lost patience. Session is cleaned up in outer loop
                  raise RateLimitError("Max timeout reached", wait=seconds)
              value = datetime.datetime.now() + datetime.timedelta(seconds=seconds)
              with self._back_off_lock:
                  self._back_off_until = value

          def raise_response_errors(self, response):
              try:
                  return super().raise_response_errors(response)
              except (ErrorInternalServerTransientError, ErrorServerBusy) as e:
                  # Pass on the retry header value
                  retry_after = _get_retry_after(response)
                  if retry_after:
                      raise ErrorServerBusy(e.args[0], back_off=retry_after)
                  raise

  ### Ancestors

  - RetryPolicy

  ### Class variables

  `var DEFAULT_BACKOFF`

  ### Instance variables

  `var back_off_until`

    Return the back off value as a datetime. Reset the current back off value if it has expired.

    Expand source code

        @property
        def back_off_until(self):
            """Return the back off value as a datetime. Reset the current back off value if it has expired."""
            if self._back_off_until is None:
                return None
            with self._back_off_lock:
                if self._back_off_until is None:
                    return None
                if self._back_off_until < datetime.datetime.now():
                    self._back_off_until = None  # The back off value has expired. Reset
                    return None
                return self._back_off_until

  ### Methods

  `def raise_response_errors(self, response)`
    Expand source code

        def raise_response_errors(self, response):
            try:
                return super().raise_response_errors(response)
            except (ErrorInternalServerTransientError, ErrorServerBusy) as e:
                # Pass on the retry header value
                retry_after = _get_retry_after(response)
                if retry_after:
                    raise ErrorServerBusy(e.args[0], back_off=retry_after)
                raise

  ### Inherited members

  - `RetryPolicy`:
    - `back_off`
    - `fail_fast`
`class NoVerifyHTTPAdapter (pool_connections=10, pool_maxsize=10, max_retries=0, pool_block=False)`

  An HTTP adapter that ignores TLS validation errors. Use at own risk.

  Expand source code

      class NoVerifyHTTPAdapter(requests.adapters.HTTPAdapter):
          """An HTTP adapter that ignores TLS validation errors. Use at own risk."""

          def cert_verify(self, conn, url, verify, cert):
              # pylint: disable=unused-argument
              # We're overriding a method, so we have to keep the signature
              super().cert_verify(conn=conn, url=url, verify=False, cert=cert)

          def get_connection_with_tls_context(self, request, verify, proxies=None, cert=None):
              # pylint: disable=unused-argument
              # Required for requests >= 2.32.3
              # See: https://github.com/psf/requests/pull/6710
              return super().get_connection_with_tls_context(request=request, verify=False, proxies=proxies, cert=cert)

  ### Ancestors

  - requests.adapters.HTTPAdapter
  - requests.adapters.BaseAdapter

  ### Methods

  `def cert_verify(self, conn, url, verify, cert)`

    Verify a SSL certificate. This method should not be called from user code, and is only exposed for use when subclassing the :class:`HTTPAdapter <requests.adapters.HTTPAdapter>`.

    :param conn: The urllib3 connection object associated with the cert. :param url: The requested URL. :param verify: Either a boolean, in which case it controls whether we verify the server's TLS certificate, or a string, in which case it must be a path to a CA bundle to use :param cert: The SSL certificate to verify.

    Expand source code

        def cert_verify(self, conn, url, verify, cert):
            # pylint: disable=unused-argument
            # We're overriding a method, so we have to keep the signature
            super().cert_verify(conn=conn, url=url, verify=False, cert=cert)

  `def get_connection_with_tls_context(self, request, verify, proxies=None, cert=None)`
    Expand source code

        def get_connection_with_tls_context(self, request, verify, proxies=None, cert=None):
            # pylint: disable=unused-argument
            # Required for requests >= 2.32.3
            # See: https://github.com/psf/requests/pull/6710
            return super().get_connection_with_tls_context(request=request, verify=False, proxies=proxies, cert=cert)

`class Protocol (*args, **kwargs)`

  A class to handle all the low-level communication with an Exchange server. Contains a session pool, knows how to negotiate the authentication type of the server, refresh credentials, etc. Also contains methods for calling EWS services that are not tied to an account.

  Expand source code

      class Protocol(BaseProtocol, metaclass=CachingProtocol):
          """A class to handle all the low-level communication with an Exchange server. Contains a session pool, knows how to
          negotiate the authentication type of the server, refresh credentials, etc. Also contains methods for calling EWS
          services that are not tied to an account.
          """

          def __init__(self, *args, **kwargs):
              super().__init__(*args, **kwargs)
              self._version_lock = Lock()
              self.api_version_hint = None

          def get_auth_type(self):
              # Autodetect authentication type. We also set 'self.api_version_hint' here.
              return get_service_authtype(protocol=self)

          @property
          def version(self):
              # Make sure only one thread does the guessing.
              if not self.config.version or not self.config.version.build:
                  log.debug("Waiting for _version_lock")
                  with self._version_lock:
                      if not self.config.version or not self.config.version.build:
                          # Version.guess() needs auth objects and a working session pool
                          self.config.version = Version.guess(self, api_version_hint=self.api_version_hint)
              return self.config.version

          def get_timezones(self, timezones=None, return_full_timezone_data=False):
              """Get timezone definitions from the server.

              :param timezones: A list of EWSDateTime instances. If None, fetches all timezones from server
                (Default value = None)
              :param return_full_timezone_data: If true, also returns periods and transitions (Default value = False)

              :return: A generator of TimeZoneDefinition objects
              """
              return GetServerTimeZones(protocol=self).call(
                  timezones=timezones, return_full_timezone_data=return_full_timezone_data
              )

          def get_free_busy_info(self, accounts, start, end, merged_free_busy_interval=30, requested_view="DetailedMerged"):
              """Return free/busy information for a list of accounts.

              :param accounts: A list of (account, attendee_type, exclude_conflicts) tuples, where account is either an
                Account object or a string, attendee_type is a MailboxData.attendee_type choice, and exclude_conflicts is a
                boolean.
              :param start: The start datetime of the request
              :param end: The end datetime of the request
              :param merged_free_busy_interval: The interval, in minutes, of merged free/busy information (Default value = 30)
              :param requested_view: The type of information returned. Possible values are defined in the
                FreeBusyViewOptions.requested_view choices. (Default value = 'DetailedMerged')

              :return: A generator of FreeBusyView objects
              """
              from .account import Account

              tz_definition = list(self.get_timezones(timezones=[start.tzinfo], return_full_timezone_data=True))[0]
              return GetUserAvailability(self).call(
                  tzinfo=start.tzinfo,
                  mailbox_data=[
                      MailboxData(
                          email=account.primary_smtp_address if isinstance(account, Account) else account,
                          attendee_type=attendee_type,
                          exclude_conflicts=exclude_conflicts,
                      )
                      for account, attendee_type, exclude_conflicts in accounts
                  ],
                  timezone=TimeZone.from_server_timezone(tz_definition=tz_definition, for_year=start.year),
                  free_busy_view_options=FreeBusyViewOptions(
                      time_window=TimeWindow(start=start, end=end),
                      merged_free_busy_interval=merged_free_busy_interval,
                      requested_view=requested_view,
                  ),
              )

          def get_roomlists(self):
              return GetRoomLists(protocol=self).call()

          def get_rooms(self, roomlist):
              return GetRooms(protocol=self).call(room_list=RoomList(email_address=roomlist))

          def resolve_names(self, names, parent_folders=None, return_full_contact_data=False, search_scope=None, shape=None):
              """Resolve accounts on the server using partial account data, e.g. an email address or initials.

              :param names: A list of identifiers to query
              :param parent_folders: A list of contact folders to search in
              :param return_full_contact_data: If True, returns full contact data (Default value = False)
              :param search_scope: The scope to perform the search. Must be one of SEARCH_SCOPE_CHOICES (Default value = None)
              :param shape: (Default value = None)

              :return: A list of Mailbox items or, if return_full_contact_data is True, tuples of (Mailbox, Contact) items
              """
              return list(
                  ResolveNames(protocol=self).call(
                      unresolved_entries=names,
                      parent_folders=parent_folders,
                      return_full_contact_data=return_full_contact_data,
                      search_scope=search_scope,
                      contact_data_shape=shape,
                  )
              )

          def expand_dl(self, distribution_list):
              """Expand distribution list into its members.

              :param distribution_list: SMTP address of the distribution list to expand, or a DLMailbox representing the list

              :return: List of Mailbox items that are members of the distribution list
              """
              if isinstance(distribution_list, str):
                  distribution_list = DLMailbox(email_address=distribution_list, mailbox_type="PublicDL")
              return list(ExpandDL(protocol=self).call(distribution_list=distribution_list))

          def get_searchable_mailboxes(self, search_filter=None, expand_group_membership=False):
              """Call the GetSearchableMailboxes service to get mailboxes that can be searched.

              This method is only available to users who have been assigned the Discovery Management RBAC role. See
              https://docs.microsoft.com/en-us/exchange/permissions-exo/permissions-exo

              :param search_filter: If set, must be a single email alias (Default value = None)
              :param expand_group_membership: If True, returned distribution lists are expanded (Default value = False)

              :return: a list of SearchableMailbox, FailedMailbox or Exception instances
              """
              return list(
                  GetSearchableMailboxes(protocol=self).call(
                      search_filter=search_filter,
                      expand_group_membership=expand_group_membership,
                  )
              )

          def convert_ids(self, ids, destination_format):
              """Convert item and folder IDs between multiple formats.

              :param ids: a list of AlternateId, AlternatePublicFolderId or AlternatePublicFolderItemId instances
              :param destination_format: A string

              :return: a generator of AlternateId, AlternatePublicFolderId or AlternatePublicFolderItemId instances
              """
              return ConvertId(protocol=self).call(items=ids, destination_format=destination_format)

          def dummy_xml(self):
              # Generate a minimal, valid EWS request
              svc = ConvertId(protocol=self)
              return svc.wrap(
                  content=svc.get_payload(
                      items=[AlternateId(id="DUMMY", format=EWS_ID, mailbox="DUMMY")],
                      destination_format=ENTRY_ID,
                  ),
                  api_version=self.api_version_hint,
              )

          def __getstate__(self):
              # The lock cannot be pickled
              state = super().__getstate__()
              del state["_version_lock"]
              return state

          def __setstate__(self, state):
              # Restore the lock
              super().__setstate__(state)
              self._version_lock = Lock()

          def __str__(self):
              # Don't trigger version guessing here just for the sake of printing
              if self.config.version:
                  fullname, api_version, build = self.version.fullname, self.version.api_version, self.version.build
              else:
                  fullname, api_version, build = "[unknown]", "[unknown]", "[unknown]"

              return f"""\
      EWS url: {self.service_endpoint}
      Product name: {fullname}
      EWS API version: {api_version}
      Build number: {build}
      EWS auth: {self.auth_type}"""

  ### Ancestors

  - BaseProtocol

  ### Instance variables

  `var version`
    Expand source code

        @property
        def version(self):
            # Make sure only one thread does the guessing.
            if not self.config.version or not self.config.version.build:
                log.debug("Waiting for _version_lock")
                with self._version_lock:
                    if not self.config.version or not self.config.version.build:
                        # Version.guess() needs auth objects and a working session pool
                        self.config.version = Version.guess(self, api_version_hint=self.api_version_hint)
            return self.config.version

  ### Methods

  `def convert_ids(self, ids, destination_format)`

    Convert item and folder IDs between multiple formats.

    :param ids: a list of AlternateId, AlternatePublicFolderId or AlternatePublicFolderItemId instances :param destination_format: A string

    :return: a generator of AlternateId, AlternatePublicFolderId or AlternatePublicFolderItemId instances

    Expand source code

        def convert_ids(self, ids, destination_format):
            """Convert item and folder IDs between multiple formats.

            :param ids: a list of AlternateId, AlternatePublicFolderId or AlternatePublicFolderItemId instances
            :param destination_format: A string

            :return: a generator of AlternateId, AlternatePublicFolderId or AlternatePublicFolderItemId instances
            """
            return ConvertId(protocol=self).call(items=ids, destination_format=destination_format)

  `def dummy_xml(self)`
    Expand source code

        def dummy_xml(self):
            # Generate a minimal, valid EWS request
            svc = ConvertId(protocol=self)
            return svc.wrap(
                content=svc.get_payload(
                    items=[AlternateId(id="DUMMY", format=EWS_ID, mailbox="DUMMY")],
                    destination_format=ENTRY_ID,
                ),
                api_version=self.api_version_hint,
            )

  `def expand_dl(self, distribution_list)`

    Expand distribution list into its members.

    :param distribution_list: SMTP address of the distribution list to expand, or a DLMailbox representing the list

    :return: List of Mailbox items that are members of the distribution list

    Expand source code

        def expand_dl(self, distribution_list):
            """Expand distribution list into its members.

            :param distribution_list: SMTP address of the distribution list to expand, or a DLMailbox representing the list

            :return: List of Mailbox items that are members of the distribution list
            """
            if isinstance(distribution_list, str):
                distribution_list = DLMailbox(email_address=distribution_list, mailbox_type="PublicDL")
            return list(ExpandDL(protocol=self).call(distribution_list=distribution_list))

  `def get_free_busy_info(self, accounts, start, end, merged_free_busy_interval=30, requested_view='DetailedMerged')`

    Return free/busy information for a list of accounts.

    :param accounts: A list of (account, attendee_type, exclude_conflicts) tuples, where account is either an Account object or a string, attendee_type is a MailboxData.attendee_type choice, and exclude_conflicts is a boolean. :param start: The start datetime of the request :param end: The end datetime of the request :param merged_free_busy_interval: The interval, in minutes, of merged free/busy information (Default value = 30) :param requested_view: The type of information returned. Possible values are defined in the FreeBusyViewOptions.requested_view choices. (Default value = 'DetailedMerged')

    :return: A generator of FreeBusyView objects

    Expand source code

        def get_free_busy_info(self, accounts, start, end, merged_free_busy_interval=30, requested_view="DetailedMerged"):
            """Return free/busy information for a list of accounts.

            :param accounts: A list of (account, attendee_type, exclude_conflicts) tuples, where account is either an
              Account object or a string, attendee_type is a MailboxData.attendee_type choice, and exclude_conflicts is a
              boolean.
            :param start: The start datetime of the request
            :param end: The end datetime of the request
            :param merged_free_busy_interval: The interval, in minutes, of merged free/busy information (Default value = 30)
            :param requested_view: The type of information returned. Possible values are defined in the
              FreeBusyViewOptions.requested_view choices. (Default value = 'DetailedMerged')

            :return: A generator of FreeBusyView objects
            """
            from .account import Account

            tz_definition = list(self.get_timezones(timezones=[start.tzinfo], return_full_timezone_data=True))[0]
            return GetUserAvailability(self).call(
                tzinfo=start.tzinfo,
                mailbox_data=[
                    MailboxData(
                        email=account.primary_smtp_address if isinstance(account, Account) else account,
                        attendee_type=attendee_type,
                        exclude_conflicts=exclude_conflicts,
                    )
                    for account, attendee_type, exclude_conflicts in accounts
                ],
                timezone=TimeZone.from_server_timezone(tz_definition=tz_definition, for_year=start.year),
                free_busy_view_options=FreeBusyViewOptions(
                    time_window=TimeWindow(start=start, end=end),
                    merged_free_busy_interval=merged_free_busy_interval,
                    requested_view=requested_view,
                ),
            )

  `def get_roomlists(self)`
    Expand source code

        def get_roomlists(self):
            return GetRoomLists(protocol=self).call()

  `def get_rooms(self, roomlist)`
    Expand source code

        def get_rooms(self, roomlist):
            return GetRooms(protocol=self).call(room_list=RoomList(email_address=roomlist))

  `def get_searchable_mailboxes(self, search_filter=None, expand_group_membership=False)`

    Call the GetSearchableMailboxes service to get mailboxes that can be searched.

    This method is only available to users who have been assigned the Discovery Management RBAC role. See https://docs.microsoft.com/en-us/exchange/permissions-exo/permissions-exo

    :param search_filter: If set, must be a single email alias (Default value = None) :param expand_group_membership: If True, returned distribution lists are expanded (Default value = False)

    :return: a list of SearchableMailbox, FailedMailbox or Exception instances

    Expand source code

        def get_searchable_mailboxes(self, search_filter=None, expand_group_membership=False):
            """Call the GetSearchableMailboxes service to get mailboxes that can be searched.

            This method is only available to users who have been assigned the Discovery Management RBAC role. See
            https://docs.microsoft.com/en-us/exchange/permissions-exo/permissions-exo

            :param search_filter: If set, must be a single email alias (Default value = None)
            :param expand_group_membership: If True, returned distribution lists are expanded (Default value = False)

            :return: a list of SearchableMailbox, FailedMailbox or Exception instances
            """
            return list(
                GetSearchableMailboxes(protocol=self).call(
                    search_filter=search_filter,
                    expand_group_membership=expand_group_membership,
                )
            )

  `def get_timezones(self, timezones=None, return_full_timezone_data=False)`

    Get timezone definitions from the server.

    :param timezones: A list of EWSDateTime instances. If None, fetches all timezones from server (Default value = None) :param return_full_timezone_data: If true, also returns periods and transitions (Default value = False)

    :return: A generator of TimeZoneDefinition objects

    Expand source code

        def get_timezones(self, timezones=None, return_full_timezone_data=False):
            """Get timezone definitions from the server.

            :param timezones: A list of EWSDateTime instances. If None, fetches all timezones from server
              (Default value = None)
            :param return_full_timezone_data: If true, also returns periods and transitions (Default value = False)

            :return: A generator of TimeZoneDefinition objects
            """
            return GetServerTimeZones(protocol=self).call(
                timezones=timezones, return_full_timezone_data=return_full_timezone_data
            )

  `def resolve_names(self, names, parent_folders=None, return_full_contact_data=False, search_scope=None, shape=None)`

    Resolve accounts on the server using partial account data, e.g. an email address or initials.

    :param names: A list of identifiers to query :param parent_folders: A list of contact folders to search in :param return_full_contact_data: If True, returns full contact data (Default value = False) :param search_scope: The scope to perform the search. Must be one of SEARCH_SCOPE_CHOICES (Default value = None) :param shape: (Default value = None)

    :return: A list of Mailbox items or, if return_full_contact_data is True, tuples of (Mailbox, Contact) items

    Expand source code

        def resolve_names(self, names, parent_folders=None, return_full_contact_data=False, search_scope=None, shape=None):
            """Resolve accounts on the server using partial account data, e.g. an email address or initials.

            :param names: A list of identifiers to query
            :param parent_folders: A list of contact folders to search in
            :param return_full_contact_data: If True, returns full contact data (Default value = False)
            :param search_scope: The scope to perform the search. Must be one of SEARCH_SCOPE_CHOICES (Default value = None)
            :param shape: (Default value = None)

            :return: A list of Mailbox items or, if return_full_contact_data is True, tuples of (Mailbox, Contact) items
            """
            return list(
                ResolveNames(protocol=self).call(
                    unresolved_entries=names,
                    parent_folders=parent_folders,
                    return_full_contact_data=return_full_contact_data,
                    search_scope=search_scope,
                    contact_data_shape=shape,
                )
            )

  ### Inherited members

  - `BaseProtocol`:
    - `HTTP_ADAPTER_CLS`
    - `decrease_poolsize`
    - `get_auth_type`
    - `increase_poolsize`
`class RetryPolicy`

  Stores retry logic used when faced with errors from the server.

  Expand source code

      class RetryPolicy(metaclass=abc.ABCMeta):
          """Stores retry logic used when faced with errors from the server."""

          @property
          @abc.abstractmethod
          def fail_fast(self):
              """Used to choose the error handling policy. When True, a fault-tolerant policy is used. False, a fail-fast
              policy is used."""

          @property
          @abc.abstractmethod
          def back_off_until(self):
              """Return a datetime to back off until"""

          @back_off_until.setter
          @abc.abstractmethod
          def back_off_until(self, value):
              """Setter for back off values"""

          @abc.abstractmethod
          def back_off(self, seconds):
              """Set a new back off until value"""

          def raise_response_errors(self, response):
              if response.status_code == 200:
                  # Response is OK
                  return
              if response.status_code == 500 and response.content and is_xml(response.content):
                  # Some genius at Microsoft thinks it's OK to send a valid SOAP response as an HTTP 500
                  log.debug("Got status code %s but trying to parse content anyway", response.status_code)
                  return
              cas_error = response.headers.get("X-CasErrorCode")
              if cas_error:
                  if cas_error.startswith("CAS error:"):
                      # Remove unnecessary text
                      cas_error = cas_error.split(":", 1)[1].strip()
                  raise CASError(cas_error=cas_error, response=response)
              if response.status_code == 500 and (
                  b"The specified server version is invalid" in response.content
                  or b"ErrorInvalidSchemaVersionForMailboxVersion" in response.content
              ):
                  # Another way of communicating invalid schema versions
                  raise ErrorInvalidSchemaVersionForMailboxVersion("Invalid server version")
              if response.headers.get("connection") == "close":
                  # Connection closed. OK to retry.
                  raise ErrorServerBusy("Caused by closed connection")
              if (
                  response.status_code == 302
                  and response.headers.get("location", "").lower()
                  == "/ews/genericerrorpage.htm?aspxerrorpath=/ews/exchange.asmx"
              ):
                  # Redirect to genericerrorpage.htm is ridiculous behaviour for random outages. OK to retry.
                  #
                  # Redirect to '/internalsite/internalerror.asp' or '/internalsite/initparams.aspx' is caused by e.g. TLS
                  # certificate f*ckups on the Exchange server. We should not retry those.
                  raise ErrorInternalServerTransientError(f"Caused by HTTP 302 redirect to {response.headers['location']}")
              if response.status_code in (301, 302):
                  try:
                      redirect_url = get_redirect_url(response=response, allow_relative=False)
                  except RelativeRedirect as e:
                      log.debug("Redirect not allowed but we were relative redirected (%s -> %s)", response.url, e.value)
                      raise RedirectError(url=e.value)
                  log.debug("Redirect not allowed but we were redirected ( (%s -> %s)", response.url, redirect_url)
                  raise RedirectError(url=redirect_url)
              if b"The referenced account is currently locked out" in response.content:
                  raise UnauthorizedError("The referenced account is currently locked out")
              if response.status_code == 401 and self.fail_fast:
                  # This is a login failure
                  raise UnauthorizedError(f"Invalid credentials for {response.url}")
              if response.status_code == 401:
                  # EWS sometimes throws 401's when it wants us to throttle connections. OK to retry.
                  raise ErrorServerBusy("Caused by HTTP 401 response")
              if response.status_code == 500 and b"Server Error in '/EWS' Application" in response.content:
                  # "Server Error in '/EWS' Application" has been seen in highly concurrent settings. OK to retry.
                  raise ErrorInternalServerTransientError("Caused by \"Server Error in 'EWS' Application\"")
              if response.status_code == 503:
                  # Internal server error. OK to retry.
                  raise ErrorInternalServerTransientError("Caused by HTTP 503 response")
              # This could be anything. Let higher layers handle this
              raise MalformedResponseError(
                  f"Unknown failure in response. Code: {response.status_code} headers: {response.headers} "
                  f"content: {response.text}"
              )

  ### Subclasses

  - FailFast
  - FaultTolerance

  ### Instance variables

  `var back_off_until`

    Return a datetime to back off until

    Expand source code

        @property
        @abc.abstractmethod
        def back_off_until(self):
            """Return a datetime to back off until"""

  `var fail_fast`

    Used to choose the error handling policy. When True, a fault-tolerant policy is used. False, a fail-fast policy is used.

    Expand source code

        @property
        @abc.abstractmethod
        def fail_fast(self):
            """Used to choose the error handling policy. When True, a fault-tolerant policy is used. False, a fail-fast
            policy is used."""

  ### Methods

  `def back_off(self, seconds)`

    Set a new back off until value

    Expand source code

        @abc.abstractmethod
        def back_off(self, seconds):
            """Set a new back off until value"""

  `def raise_response_errors(self, response)`
    Expand source code

        def raise_response_errors(self, response):
            if response.status_code == 200:
                # Response is OK
                return
            if response.status_code == 500 and response.content and is_xml(response.content):
                # Some genius at Microsoft thinks it's OK to send a valid SOAP response as an HTTP 500
                log.debug("Got status code %s but trying to parse content anyway", response.status_code)
                return
            cas_error = response.headers.get("X-CasErrorCode")
            if cas_error:
                if cas_error.startswith("CAS error:"):
                    # Remove unnecessary text
                    cas_error = cas_error.split(":", 1)[1].strip()
                raise CASError(cas_error=cas_error, response=response)
            if response.status_code == 500 and (
                b"The specified server version is invalid" in response.content
                or b"ErrorInvalidSchemaVersionForMailboxVersion" in response.content
            ):
                # Another way of communicating invalid schema versions
                raise ErrorInvalidSchemaVersionForMailboxVersion("Invalid server version")
            if response.headers.get("connection") == "close":
                # Connection closed. OK to retry.
                raise ErrorServerBusy("Caused by closed connection")
            if (
                response.status_code == 302
                and response.headers.get("location", "").lower()
                == "/ews/genericerrorpage.htm?aspxerrorpath=/ews/exchange.asmx"
            ):
                # Redirect to genericerrorpage.htm is ridiculous behaviour for random outages. OK to retry.
                #
                # Redirect to '/internalsite/internalerror.asp' or '/internalsite/initparams.aspx' is caused by e.g. TLS
                # certificate f*ckups on the Exchange server. We should not retry those.
                raise ErrorInternalServerTransientError(f"Caused by HTTP 302 redirect to {response.headers['location']}")
            if response.status_code in (301, 302):
                try:
                    redirect_url = get_redirect_url(response=response, allow_relative=False)
                except RelativeRedirect as e:
                    log.debug("Redirect not allowed but we were relative redirected (%s -> %s)", response.url, e.value)
                    raise RedirectError(url=e.value)
                log.debug("Redirect not allowed but we were redirected ( (%s -> %s)", response.url, redirect_url)
                raise RedirectError(url=redirect_url)
            if b"The referenced account is currently locked out" in response.content:
                raise UnauthorizedError("The referenced account is currently locked out")
            if response.status_code == 401 and self.fail_fast:
                # This is a login failure
                raise UnauthorizedError(f"Invalid credentials for {response.url}")
            if response.status_code == 401:
                # EWS sometimes throws 401's when it wants us to throttle connections. OK to retry.
                raise ErrorServerBusy("Caused by HTTP 401 response")
            if response.status_code == 500 and b"Server Error in '/EWS' Application" in response.content:
                # "Server Error in '/EWS' Application" has been seen in highly concurrent settings. OK to retry.
                raise ErrorInternalServerTransientError("Caused by \"Server Error in 'EWS' Application\"")
            if response.status_code == 503:
                # Internal server error. OK to retry.
                raise ErrorInternalServerTransientError("Caused by HTTP 503 response")
            # This could be anything. Let higher layers handle this
            raise MalformedResponseError(
                f"Unknown failure in response. Code: {response.status_code} headers: {response.headers} "
                f"content: {response.text}"
            )

`class TLSClientAuth (pool_connections=10, pool_maxsize=10, max_retries=0, pool_block=False)`

  An HTTP adapter that implements Certificate Based Authentication (CBA).

  Expand source code

      class TLSClientAuth(requests.adapters.HTTPAdapter):
          """An HTTP adapter that implements Certificate Based Authentication (CBA)."""

          cert_file = None

          def init_poolmanager(self, *args, **kwargs):
              kwargs["cert_file"] = self.cert_file
              return super().init_poolmanager(*args, **kwargs)

  ### Ancestors

  - requests.adapters.HTTPAdapter
  - requests.adapters.BaseAdapter

  ### Class variables

  `var cert_file`

  ### Methods

  `def init_poolmanager(self, *args, **kwargs)`

    Initializes a urllib3 PoolManager.

    This method should not be called from user code, and is only exposed for use when subclassing the :class:`HTTPAdapter <requests.adapters.HTTPAdapter>`.

    :param connections: The number of urllib3 connection pools to cache. :param maxsize: The maximum number of connections to save in the pool. :param block: Block when no free connections are available. :param pool_kwargs: Extra keyword arguments used to initialize the Pool Manager.

    Expand source code

        def init_poolmanager(self, *args, **kwargs):
            kwargs["cert_file"] = self.cert_file
            return super().init_poolmanager(*args, **kwargs)