412 lines
		
	
	
		
			16 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			412 lines
		
	
	
		
			16 KiB
		
	
	
	
		
			Python
		
	
	
# Copyright 2019 New Vector Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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#     http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import email.mime.multipart
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import email.utils
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import logging
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from typing import TYPE_CHECKING, Awaitable, Callable, List, Optional, Tuple
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from twisted.web.http import Request
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from synapse.api.errors import AuthError, StoreError, SynapseError
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from synapse.metrics.background_process_metrics import wrap_as_background_process
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from synapse.types import UserID
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from synapse.util import stringutils
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if TYPE_CHECKING:
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    from synapse.server import HomeServer
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logger = logging.getLogger(__name__)
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# Types for callbacks to be registered via the module api
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IS_USER_EXPIRED_CALLBACK = Callable[[str], Awaitable[Optional[bool]]]
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ON_USER_REGISTRATION_CALLBACK = Callable[[str], Awaitable]
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# Temporary hooks to allow for a transition from `/_matrix/client` endpoints
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# to `/_synapse/client/account_validity`. See `register_account_validity_callbacks`.
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ON_LEGACY_SEND_MAIL_CALLBACK = Callable[[str], Awaitable]
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ON_LEGACY_RENEW_CALLBACK = Callable[[str], Awaitable[Tuple[bool, bool, int]]]
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ON_LEGACY_ADMIN_REQUEST = Callable[[Request], Awaitable]
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class AccountValidityHandler:
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    def __init__(self, hs: "HomeServer"):
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        self.hs = hs
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        self.config = hs.config
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        self.store = self.hs.get_datastore()
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        self.send_email_handler = self.hs.get_send_email_handler()
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        self.clock = self.hs.get_clock()
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        self._app_name = self.hs.config.email_app_name
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        self._account_validity_enabled = (
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            hs.config.account_validity.account_validity_enabled
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        )
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        self._account_validity_renew_by_email_enabled = (
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            hs.config.account_validity.account_validity_renew_by_email_enabled
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        )
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        self._account_validity_period = None
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        if self._account_validity_enabled:
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            self._account_validity_period = (
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                hs.config.account_validity.account_validity_period
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            )
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        if (
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            self._account_validity_enabled
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            and self._account_validity_renew_by_email_enabled
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        ):
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            # Don't do email-specific configuration if renewal by email is disabled.
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            self._template_html = (
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                hs.config.account_validity.account_validity_template_html
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            )
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            self._template_text = (
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                hs.config.account_validity.account_validity_template_text
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            )
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            self._renew_email_subject = (
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                hs.config.account_validity.account_validity_renew_email_subject
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            )
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            # Check the renewal emails to send and send them every 30min.
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            if hs.config.run_background_tasks:
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                self.clock.looping_call(self._send_renewal_emails, 30 * 60 * 1000)
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        self._is_user_expired_callbacks: List[IS_USER_EXPIRED_CALLBACK] = []
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        self._on_user_registration_callbacks: List[ON_USER_REGISTRATION_CALLBACK] = []
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        self._on_legacy_send_mail_callback: Optional[
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            ON_LEGACY_SEND_MAIL_CALLBACK
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        ] = None
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        self._on_legacy_renew_callback: Optional[ON_LEGACY_RENEW_CALLBACK] = None
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        # The legacy admin requests callback isn't a protected attribute because we need
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        # to access it from the admin servlet, which is outside of this handler.
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        self.on_legacy_admin_request_callback: Optional[ON_LEGACY_ADMIN_REQUEST] = None
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    def register_account_validity_callbacks(
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        self,
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        is_user_expired: Optional[IS_USER_EXPIRED_CALLBACK] = None,
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        on_user_registration: Optional[ON_USER_REGISTRATION_CALLBACK] = None,
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        on_legacy_send_mail: Optional[ON_LEGACY_SEND_MAIL_CALLBACK] = None,
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        on_legacy_renew: Optional[ON_LEGACY_RENEW_CALLBACK] = None,
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        on_legacy_admin_request: Optional[ON_LEGACY_ADMIN_REQUEST] = None,
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    ):
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        """Register callbacks from module for each hook."""
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        if is_user_expired is not None:
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            self._is_user_expired_callbacks.append(is_user_expired)
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        if on_user_registration is not None:
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            self._on_user_registration_callbacks.append(on_user_registration)
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        # The builtin account validity feature exposes 3 endpoints (send_mail, renew, and
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        # an admin one). As part of moving the feature into a module, we need to change
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        # the path from /_matrix/client/unstable/account_validity/... to
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        # /_synapse/client/account_validity, because:
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        #
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        #   * the feature isn't part of the Matrix spec thus shouldn't live under /_matrix
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        #   * the way we register servlets means that modules can't register resources
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        #     under /_matrix/client
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        #
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        # We need to allow for a transition period between the old and new endpoints
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        # in order to allow for clients to update (and for emails to be processed).
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        #
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        # Once the email-account-validity module is loaded, it will take control of account
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        # validity by moving the rows from our `account_validity` table into its own table.
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        #
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        # Therefore, we need to allow modules (in practice just the one implementing the
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        # email-based account validity) to temporarily hook into the legacy endpoints so we
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        # can route the traffic coming into the old endpoints into the module, which is
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        # why we have the following three temporary hooks.
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        if on_legacy_send_mail is not None:
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            if self._on_legacy_send_mail_callback is not None:
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                raise RuntimeError("Tried to register on_legacy_send_mail twice")
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            self._on_legacy_send_mail_callback = on_legacy_send_mail
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        if on_legacy_renew is not None:
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            if self._on_legacy_renew_callback is not None:
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                raise RuntimeError("Tried to register on_legacy_renew twice")
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            self._on_legacy_renew_callback = on_legacy_renew
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        if on_legacy_admin_request is not None:
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            if self.on_legacy_admin_request_callback is not None:
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                raise RuntimeError("Tried to register on_legacy_admin_request twice")
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            self.on_legacy_admin_request_callback = on_legacy_admin_request
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    async def is_user_expired(self, user_id: str) -> bool:
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        """Checks if a user has expired against third-party modules.
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        Args:
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            user_id: The user to check the expiry of.
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        Returns:
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            Whether the user has expired.
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        """
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        for callback in self._is_user_expired_callbacks:
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            expired = await callback(user_id)
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            if expired is not None:
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                return expired
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        if self._account_validity_enabled:
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            # If no module could determine whether the user has expired and the legacy
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            # configuration is enabled, fall back to it.
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            return await self.store.is_account_expired(user_id, self.clock.time_msec())
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        return False
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    async def on_user_registration(self, user_id: str):
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        """Tell third-party modules about a user's registration.
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        Args:
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            user_id: The ID of the newly registered user.
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        """
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        for callback in self._on_user_registration_callbacks:
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            await callback(user_id)
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    @wrap_as_background_process("send_renewals")
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    async def _send_renewal_emails(self) -> None:
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        """Gets the list of users whose account is expiring in the amount of time
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        configured in the ``renew_at`` parameter from the ``account_validity``
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        configuration, and sends renewal emails to all of these users as long as they
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        have an email 3PID attached to their account.
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        """
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        expiring_users = await self.store.get_users_expiring_soon()
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        if expiring_users:
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            for user in expiring_users:
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                await self._send_renewal_email(
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                    user_id=user["user_id"], expiration_ts=user["expiration_ts_ms"]
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                )
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    async def send_renewal_email_to_user(self, user_id: str) -> None:
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        """
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        Send a renewal email for a specific user.
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        Args:
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            user_id: The user ID to send a renewal email for.
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        Raises:
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            SynapseError if the user is not set to renew.
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        """
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        # If a module supports sending a renewal email from here, do that, otherwise do
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        # the legacy dance.
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        if self._on_legacy_send_mail_callback is not None:
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            await self._on_legacy_send_mail_callback(user_id)
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            return
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        if not self._account_validity_renew_by_email_enabled:
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            raise AuthError(
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                403, "Account renewal via email is disabled on this server."
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            )
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        expiration_ts = await self.store.get_expiration_ts_for_user(user_id)
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        # If this user isn't set to be expired, raise an error.
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        if expiration_ts is None:
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            raise SynapseError(400, "User has no expiration time: %s" % (user_id,))
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        await self._send_renewal_email(user_id, expiration_ts)
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    async def _send_renewal_email(self, user_id: str, expiration_ts: int) -> None:
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        """Sends out a renewal email to every email address attached to the given user
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        with a unique link allowing them to renew their account.
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        Args:
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            user_id: ID of the user to send email(s) to.
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            expiration_ts: Timestamp in milliseconds for the expiration date of
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                this user's account (used in the email templates).
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        """
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        addresses = await self._get_email_addresses_for_user(user_id)
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        # Stop right here if the user doesn't have at least one email address.
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        # In this case, they will have to ask their server admin to renew their
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        # account manually.
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        # We don't need to do a specific check to make sure the account isn't
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        # deactivated, as a deactivated account isn't supposed to have any
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        # email address attached to it.
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        if not addresses:
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            return
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        try:
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            user_display_name = await self.store.get_profile_displayname(
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                UserID.from_string(user_id).localpart
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            )
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            if user_display_name is None:
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                user_display_name = user_id
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        except StoreError:
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            user_display_name = user_id
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        renewal_token = await self._get_renewal_token(user_id)
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        url = "%s_matrix/client/unstable/account_validity/renew?token=%s" % (
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            self.hs.config.public_baseurl,
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            renewal_token,
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        )
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        template_vars = {
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            "display_name": user_display_name,
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            "expiration_ts": expiration_ts,
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            "url": url,
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        }
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        html_text = self._template_html.render(**template_vars)
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        plain_text = self._template_text.render(**template_vars)
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        for address in addresses:
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            raw_to = email.utils.parseaddr(address)[1]
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            await self.send_email_handler.send_email(
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                email_address=raw_to,
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                subject=self._renew_email_subject,
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                app_name=self._app_name,
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                html=html_text,
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                text=plain_text,
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            )
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        await self.store.set_renewal_mail_status(user_id=user_id, email_sent=True)
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    async def _get_email_addresses_for_user(self, user_id: str) -> List[str]:
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        """Retrieve the list of email addresses attached to a user's account.
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        Args:
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            user_id: ID of the user to lookup email addresses for.
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        Returns:
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            Email addresses for this account.
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        """
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        threepids = await self.store.user_get_threepids(user_id)
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        addresses = []
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        for threepid in threepids:
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            if threepid["medium"] == "email":
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                addresses.append(threepid["address"])
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        return addresses
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    async def _get_renewal_token(self, user_id: str) -> str:
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        """Generates a 32-byte long random string that will be inserted into the
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        user's renewal email's unique link, then saves it into the database.
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        Args:
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            user_id: ID of the user to generate a string for.
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        Returns:
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            The generated string.
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        Raises:
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            StoreError(500): Couldn't generate a unique string after 5 attempts.
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        """
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        attempts = 0
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        while attempts < 5:
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            try:
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                renewal_token = stringutils.random_string(32)
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                await self.store.set_renewal_token_for_user(user_id, renewal_token)
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                return renewal_token
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            except StoreError:
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                attempts += 1
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        raise StoreError(500, "Couldn't generate a unique string as refresh string.")
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    async def renew_account(self, renewal_token: str) -> Tuple[bool, bool, int]:
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        """Renews the account attached to a given renewal token by pushing back the
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        expiration date by the current validity period in the server's configuration.
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        If it turns out that the token is valid but has already been used, then the
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        token is considered stale. A token is stale if the 'token_used_ts_ms' db column
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        is non-null.
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        This method exists to support handling the legacy account validity /renew
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        endpoint. If a module implements the on_legacy_renew callback, then this process
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        is delegated to the module instead.
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        Args:
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            renewal_token: Token sent with the renewal request.
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        Returns:
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            A tuple containing:
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              * A bool representing whether the token is valid and unused.
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              * A bool which is `True` if the token is valid, but stale.
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              * An int representing the user's expiry timestamp as milliseconds since the
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                epoch, or 0 if the token was invalid.
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        """
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        # If a module supports triggering a renew from here, do that, otherwise do the
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        # legacy dance.
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        if self._on_legacy_renew_callback is not None:
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            return await self._on_legacy_renew_callback(renewal_token)
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        try:
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            (
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                user_id,
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                current_expiration_ts,
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                token_used_ts,
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            ) = await self.store.get_user_from_renewal_token(renewal_token)
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        except StoreError:
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            return False, False, 0
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        # Check whether this token has already been used.
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        if token_used_ts:
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            logger.info(
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                "User '%s' attempted to use previously used token '%s' to renew account",
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                user_id,
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                renewal_token,
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            )
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            return False, True, current_expiration_ts
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        logger.debug("Renewing an account for user %s", user_id)
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        # Renew the account. Pass the renewal_token here so that it is not cleared.
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        # We want to keep the token around in case the user attempts to renew their
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        # account with the same token twice (clicking the email link twice).
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        #
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        # In that case, the token will be accepted, but the account's expiration ts
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        # will remain unchanged.
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        new_expiration_ts = await self.renew_account_for_user(
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            user_id, renewal_token=renewal_token
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        )
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        return True, False, new_expiration_ts
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    async def renew_account_for_user(
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        self,
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        user_id: str,
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        expiration_ts: Optional[int] = None,
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        email_sent: bool = False,
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        renewal_token: Optional[str] = None,
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    ) -> int:
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        """Renews the account attached to a given user by pushing back the
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        expiration date by the current validity period in the server's
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        configuration.
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        Args:
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            user_id: The ID of the user to renew.
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            expiration_ts: New expiration date. Defaults to now + validity period.
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            email_sent: Whether an email has been sent for this validity period.
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            renewal_token: Token sent with the renewal request. The user's token
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                will be cleared if this is None.
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        Returns:
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            New expiration date for this account, as a timestamp in
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            milliseconds since epoch.
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        """
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        now = self.clock.time_msec()
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        if expiration_ts is None:
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            expiration_ts = now + self._account_validity_period
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        await self.store.set_account_validity_for_user(
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            user_id=user_id,
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            expiration_ts=expiration_ts,
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            email_sent=email_sent,
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            renewal_token=renewal_token,
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            token_used_ts=now,
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        )
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        return expiration_ts
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