forked-synapse/synapse/storage/registration.py

# -*- coding: utf-8 -*-
# Copyright 2014-2016 OpenMarket Ltd
# Copyright 2017-2018 New Vector Ltd
# Copyright 2019 The Matrix.org Foundation C.I.C.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import re

from six import iterkeys
from six.moves import range

from twisted.internet import defer

from synapse.api.constants import UserTypes
from synapse.api.errors import Codes, StoreError, ThreepidValidationError
from synapse.storage import background_updates
from synapse.storage._base import SQLBaseStore
from synapse.types import UserID
from synapse.util.caches.descriptors import cached, cachedInlineCallbacks

THIRTY_MINUTES_IN_MS = 30 * 60 * 1000


class RegistrationWorkerStore(SQLBaseStore):
    def __init__(self, db_conn, hs):
        super(RegistrationWorkerStore, self).__init__(db_conn, hs)

        self.config = hs.config
        self.clock = hs.get_clock()

    @cached()
    def get_user_by_id(self, user_id):
        return self._simple_select_one(
            table="users",
            keyvalues={"name": user_id},
            retcols=[
                "name",
                "password_hash",
                "is_guest",
                "consent_version",
                "consent_server_notice_sent",
                "appservice_id",
                "creation_ts",
            ],
            allow_none=True,
            desc="get_user_by_id",
        )

    @defer.inlineCallbacks
    def is_trial_user(self, user_id):
        """Checks if user is in the "trial" period, i.e. within the first
        N days of registration defined by `mau_trial_days` config

        Args:
            user_id (str)

        Returns:
            Deferred[bool]
        """

        info = yield self.get_user_by_id(user_id)
        if not info:
            defer.returnValue(False)

        now = self.clock.time_msec()
        trial_duration_ms = self.config.mau_trial_days * 24 * 60 * 60 * 1000
        is_trial = (now - info["creation_ts"] * 1000) < trial_duration_ms
        defer.returnValue(is_trial)

    @cached()
    def get_user_by_access_token(self, token):
        """Get a user from the given access token.

        Args:
            token (str): The access token of a user.
        Returns:
            defer.Deferred: None, if the token did not match, otherwise dict
                including the keys `name`, `is_guest`, `device_id`, `token_id`.
        """
        return self.runInteraction(
            "get_user_by_access_token", self._query_for_auth, token
        )

    @cachedInlineCallbacks()
    def get_expiration_ts_for_user(self, user_id):
        """Get the expiration timestamp for the account bearing a given user ID.

        Args:
            user_id (str): The ID of the user.
        Returns:
            defer.Deferred: None, if the account has no expiration timestamp,
                otherwise int representation of the timestamp (as a number of
                milliseconds since epoch).
        """
        res = yield self._simple_select_one_onecol(
            table="account_validity",
            keyvalues={"user_id": user_id},
            retcol="expiration_ts_ms",
            allow_none=True,
            desc="get_expiration_ts_for_user",
        )
        defer.returnValue(res)

    @defer.inlineCallbacks
    def set_account_validity_for_user(self, user_id, expiration_ts, email_sent,
                                      renewal_token=None):
        """Updates the account validity properties of the given account, with the
        given values.

        Args:
            user_id (str): ID of the account to update properties for.
            expiration_ts (int): New expiration date, as a timestamp in milliseconds
                since epoch.
            email_sent (bool): True means a renewal email has been sent for this
                account and there's no need to send another one for the current validity
                period.
            renewal_token (str): Renewal token the user can use to extend the validity
                of their account. Defaults to no token.
        """
        def set_account_validity_for_user_txn(txn):
            self._simple_update_txn(
                txn=txn,
                table="account_validity",
                keyvalues={"user_id": user_id},
                updatevalues={
                    "expiration_ts_ms": expiration_ts,
                    "email_sent": email_sent,
                    "renewal_token": renewal_token,
                },
            )
            self._invalidate_cache_and_stream(
                txn, self.get_expiration_ts_for_user, (user_id,),
            )

        yield self.runInteraction(
            "set_account_validity_for_user",
            set_account_validity_for_user_txn,
        )

    @defer.inlineCallbacks
    def set_renewal_token_for_user(self, user_id, renewal_token):
        """Defines a renewal token for a given user.

        Args:
            user_id (str): ID of the user to set the renewal token for.
            renewal_token (str): Random unique string that will be used to renew the
                user's account.

        Raises:
            StoreError: The provided token is already set for another user.
        """
        yield self._simple_update_one(
            table="account_validity",
            keyvalues={"user_id": user_id},
            updatevalues={"renewal_token": renewal_token},
            desc="set_renewal_token_for_user",
        )

    @defer.inlineCallbacks
    def get_user_from_renewal_token(self, renewal_token):
        """Get a user ID from a renewal token.

        Args:
            renewal_token (str): The renewal token to perform the lookup with.

        Returns:
            defer.Deferred[str]: The ID of the user to which the token belongs.
        """
        res = yield self._simple_select_one_onecol(
            table="account_validity",
            keyvalues={"renewal_token": renewal_token},
            retcol="user_id",
            desc="get_user_from_renewal_token",
        )

        defer.returnValue(res)

    @defer.inlineCallbacks
    def get_renewal_token_for_user(self, user_id):
        """Get the renewal token associated with a given user ID.

        Args:
            user_id (str): The user ID to lookup a token for.

        Returns:
            defer.Deferred[str]: The renewal token associated with this user ID.
        """
        res = yield self._simple_select_one_onecol(
            table="account_validity",
            keyvalues={"user_id": user_id},
            retcol="renewal_token",
            desc="get_renewal_token_for_user",
        )

        defer.returnValue(res)

    @defer.inlineCallbacks
    def get_users_expiring_soon(self):
        """Selects users whose account will expire in the [now, now + renew_at] time
        window (see configuration for account_validity for information on what renew_at
        refers to).

        Returns:
            Deferred: Resolves to a list[dict[user_id (str), expiration_ts_ms (int)]]
        """
        def select_users_txn(txn, now_ms, renew_at):
            sql = (
                "SELECT user_id, expiration_ts_ms FROM account_validity"
                " WHERE email_sent = ? AND (expiration_ts_ms - ?) <= ?"
            )
            values = [False, now_ms, renew_at]
            txn.execute(sql, values)
            return self.cursor_to_dict(txn)

        res = yield self.runInteraction(
            "get_users_expiring_soon",
            select_users_txn,
            self.clock.time_msec(), self.config.account_validity.renew_at,
        )

        defer.returnValue(res)

    @defer.inlineCallbacks
    def set_renewal_mail_status(self, user_id, email_sent):
        """Sets or unsets the flag that indicates whether a renewal email has been sent
        to the user (and the user hasn't renewed their account yet).

        Args:
            user_id (str): ID of the user to set/unset the flag for.
            email_sent (bool): Flag which indicates whether a renewal email has been sent
                to this user.
        """
        yield self._simple_update_one(
            table="account_validity",
            keyvalues={"user_id": user_id},
            updatevalues={"email_sent": email_sent},
            desc="set_renewal_mail_status",
        )

    @defer.inlineCallbacks
    def is_server_admin(self, user):
        res = yield self._simple_select_one_onecol(
            table="users",
            keyvalues={"name": user.to_string()},
            retcol="admin",
            allow_none=True,
            desc="is_server_admin",
        )

        defer.returnValue(res if res else False)

    def _query_for_auth(self, txn, token):
        sql = (
            "SELECT users.name, users.is_guest, access_tokens.id as token_id,"
            " access_tokens.device_id"
            " FROM users"
            " INNER JOIN access_tokens on users.name = access_tokens.user_id"
            " WHERE token = ?"
        )

        txn.execute(sql, (token,))
        rows = self.cursor_to_dict(txn)
        if rows:
            return rows[0]

        return None

    @cachedInlineCallbacks()
    def is_support_user(self, user_id):
        """Determines if the user is of type UserTypes.SUPPORT

        Args:
            user_id (str): user id to test

        Returns:
            Deferred[bool]: True if user is of type UserTypes.SUPPORT
        """
        res = yield self.runInteraction(
            "is_support_user", self.is_support_user_txn, user_id
        )
        defer.returnValue(res)

    def is_support_user_txn(self, txn, user_id):
        res = self._simple_select_one_onecol_txn(
            txn=txn,
            table="users",
            keyvalues={"name": user_id},
            retcol="user_type",
            allow_none=True,
        )
        return True if res == UserTypes.SUPPORT else False

    def get_users_by_id_case_insensitive(self, user_id):
        """Gets users that match user_id case insensitively.
        Returns a mapping of user_id -> password_hash.
        """

        def f(txn):
            sql = (
                "SELECT name, password_hash FROM users" " WHERE lower(name) = lower(?)"
            )
            txn.execute(sql, (user_id,))
            return dict(txn)

        return self.runInteraction("get_users_by_id_case_insensitive", f)

    @defer.inlineCallbacks
    def count_all_users(self):
        """Counts all users registered on the homeserver."""

        def _count_users(txn):
            txn.execute("SELECT COUNT(*) AS users FROM users")
            rows = self.cursor_to_dict(txn)
            if rows:
                return rows[0]["users"]
            return 0

        ret = yield self.runInteraction("count_users", _count_users)
        defer.returnValue(ret)

    def count_daily_user_type(self):
        """
        Counts 1) native non guest users
               2) native guests users
               3) bridged users
        who registered on the homeserver in the past 24 hours
        """

        def _count_daily_user_type(txn):
            yesterday = int(self._clock.time()) - (60 * 60 * 24)

            sql = """
                SELECT user_type, COALESCE(count(*), 0) AS count FROM (
                    SELECT
                    CASE
                        WHEN is_guest=0 AND appservice_id IS NULL THEN 'native'
                        WHEN is_guest=1 AND appservice_id IS NULL THEN 'guest'
                        WHEN is_guest=0 AND appservice_id IS NOT NULL THEN 'bridged'
                    END AS user_type
                    FROM users
                    WHERE creation_ts > ?
                ) AS t GROUP BY user_type
            """
            results = {'native': 0, 'guest': 0, 'bridged': 0}
            txn.execute(sql, (yesterday,))
            for row in txn:
                results[row[0]] = row[1]
            return results

        return self.runInteraction("count_daily_user_type", _count_daily_user_type)

    @defer.inlineCallbacks
    def count_nonbridged_users(self):
        def _count_users(txn):
            txn.execute(
                """
                SELECT COALESCE(COUNT(*), 0) FROM users
                WHERE appservice_id IS NULL
            """
            )
            count, = txn.fetchone()
            return count

        ret = yield self.runInteraction("count_users", _count_users)
        defer.returnValue(ret)

    @defer.inlineCallbacks
    def find_next_generated_user_id_localpart(self):
        """
        Gets the localpart of the next generated user ID.

        Generated user IDs are integers, and we aim for them to be as small as
        we can. Unfortunately, it's possible some of them are already taken by
        existing users, and there may be gaps in the already taken range. This
        function returns the start of the first allocatable gap. This is to
        avoid the case of ID 10000000 being pre-allocated, so us wasting the
        first (and shortest) many generated user IDs.
        """

        def _find_next_generated_user_id(txn):
            txn.execute("SELECT name FROM users")

            regex = re.compile(r"^@(\d+):")

            found = set()

            for (user_id,) in txn:
                match = regex.search(user_id)
                if match:
                    found.add(int(match.group(1)))
            for i in range(len(found) + 1):
                if i not in found:
                    return i

        defer.returnValue(
            (
                yield self.runInteraction(
                    "find_next_generated_user_id", _find_next_generated_user_id
                )
            )
        )

    @defer.inlineCallbacks
    def get_3pid_guest_access_token(self, medium, address):
        ret = yield self._simple_select_one(
            "threepid_guest_access_tokens",
            {"medium": medium, "address": address},
            ["guest_access_token"],
            True,
            'get_3pid_guest_access_token',
        )
        if ret:
            defer.returnValue(ret["guest_access_token"])
        defer.returnValue(None)

    @defer.inlineCallbacks
    def get_user_id_by_threepid(self, medium, address, require_verified=False):
        """Returns user id from threepid

        Args:
            medium (str): threepid medium e.g. email
            address (str): threepid address e.g. me@example.com

        Returns:
            Deferred[str|None]: user id or None if no user id/threepid mapping exists
        """
        user_id = yield self.runInteraction(
            "get_user_id_by_threepid", self.get_user_id_by_threepid_txn, medium, address
        )
        defer.returnValue(user_id)

    def get_user_id_by_threepid_txn(self, txn, medium, address):
        """Returns user id from threepid

        Args:
            txn (cursor):
            medium (str): threepid medium e.g. email
            address (str): threepid address e.g. me@example.com

        Returns:
            str|None: user id or None if no user id/threepid mapping exists
        """
        ret = self._simple_select_one_txn(
            txn,
            "user_threepids",
            {"medium": medium, "address": address},
            ['user_id'],
            True,
        )
        if ret:
            return ret['user_id']
        return None

    @defer.inlineCallbacks
    def user_add_threepid(self, user_id, medium, address, validated_at, added_at):
        yield self._simple_upsert(
            "user_threepids",
            {"medium": medium, "address": address},
            {"user_id": user_id, "validated_at": validated_at, "added_at": added_at},
        )

    @defer.inlineCallbacks
    def user_get_threepids(self, user_id):
        ret = yield self._simple_select_list(
            "user_threepids",
            {"user_id": user_id},
            ['medium', 'address', 'validated_at', 'added_at'],
            'user_get_threepids',
        )
        defer.returnValue(ret)

    def user_delete_threepid(self, user_id, medium, address):
        return self._simple_delete(
            "user_threepids",
            keyvalues={"user_id": user_id, "medium": medium, "address": address},
            desc="user_delete_threepids",
        )

    def add_user_bound_threepid(self, user_id, medium, address, id_server):
        """The server proxied a bind request to the given identity server on
        behalf of the given user. We need to remember this in case the user
        asks us to unbind the threepid.

        Args:
            user_id (str)
            medium (str)
            address (str)
            id_server (str)

        Returns:
            Deferred
        """
        # We need to use an upsert, in case they user had already bound the
        # threepid
        return self._simple_upsert(
            table="user_threepid_id_server",
            keyvalues={
                "user_id": user_id,
                "medium": medium,
                "address": address,
                "id_server": id_server,
            },
            values={},
            insertion_values={},
            desc="add_user_bound_threepid",
        )

    def remove_user_bound_threepid(self, user_id, medium, address, id_server):
        """The server proxied an unbind request to the given identity server on
        behalf of the given user, so we remove the mapping of threepid to
        identity server.

        Args:
            user_id (str)
            medium (str)
            address (str)
            id_server (str)

        Returns:
            Deferred
        """
        return self._simple_delete(
            table="user_threepid_id_server",
            keyvalues={
                "user_id": user_id,
                "medium": medium,
                "address": address,
                "id_server": id_server,
            },
            desc="remove_user_bound_threepid",
        )

    def get_id_servers_user_bound(self, user_id, medium, address):
        """Get the list of identity servers that the server proxied bind
        requests to for given user and threepid

        Args:
            user_id (str)
            medium (str)
            address (str)

        Returns:
            Deferred[list[str]]: Resolves to a list of identity servers
        """
        return self._simple_select_onecol(
            table="user_threepid_id_server",
            keyvalues={
                "user_id": user_id,
                "medium": medium,
                "address": address,
            },
            retcol="id_server",
            desc="get_id_servers_user_bound",
        )


class RegistrationStore(
    RegistrationWorkerStore, background_updates.BackgroundUpdateStore
):
    def __init__(self, db_conn, hs):
        super(RegistrationStore, self).__init__(db_conn, hs)

        self.clock = hs.get_clock()

        self.register_background_index_update(
            "access_tokens_device_index",
            index_name="access_tokens_device_id",
            table="access_tokens",
            columns=["user_id", "device_id"],
        )

        self.register_background_index_update(
            "users_creation_ts",
            index_name="users_creation_ts",
            table="users",
            columns=["creation_ts"],
        )

        self._account_validity = hs.config.account_validity

        # we no longer use refresh tokens, but it's possible that some people
        # might have a background update queued to build this index. Just
        # clear the background update.
        self.register_noop_background_update("refresh_tokens_device_index")

        self.register_background_update_handler(
            "user_threepids_grandfather", self._bg_user_threepids_grandfather,
        )

        # Create a background job for culling expired 3PID validity tokens
        hs.get_clock().looping_call(
            self.cull_expired_threepid_validation_tokens, THIRTY_MINUTES_IN_MS,
        )

    @defer.inlineCallbacks
    def add_access_token_to_user(self, user_id, token, device_id=None):
        """Adds an access token for the given user.

        Args:
            user_id (str): The user ID.
            token (str): The new access token to add.
            device_id (str): ID of the device to associate with the access
               token
        Raises:
            StoreError if there was a problem adding this.
        """
        next_id = self._access_tokens_id_gen.get_next()

        yield self._simple_insert(
            "access_tokens",
            {"id": next_id, "user_id": user_id, "token": token, "device_id": device_id},
            desc="add_access_token_to_user",
        )

    def register(
        self,
        user_id,
        token=None,
        password_hash=None,
        was_guest=False,
        make_guest=False,
        appservice_id=None,
        create_profile_with_displayname=None,
        admin=False,
        user_type=None,
    ):
        """Attempts to register an account.

        Args:
            user_id (str): The desired user ID to register.
            token (str): The desired access token to use for this user. If this
                is not None, the given access token is associated with the user
                id.
            password_hash (str): Optional. The password hash for this user.
            was_guest (bool): Optional. Whether this is a guest account being
                upgraded to a non-guest account.
            make_guest (boolean): True if the the new user should be guest,
                false to add a regular user account.
            appservice_id (str): The ID of the appservice registering the user.
            create_profile_with_displayname (unicode): Optionally create a profile for
                the user, setting their displayname to the given value
            admin (boolean): is an admin user?
            user_type (str|None): type of user. One of the values from
                api.constants.UserTypes, or None for a normal user.

        Raises:
            StoreError if the user_id could not be registered.
        """
        return self.runInteraction(
            "register",
            self._register,
            user_id,
            token,
            password_hash,
            was_guest,
            make_guest,
            appservice_id,
            create_profile_with_displayname,
            admin,
            user_type,
        )

    def _register(
        self,
        txn,
        user_id,
        token,
        password_hash,
        was_guest,
        make_guest,
        appservice_id,
        create_profile_with_displayname,
        admin,
        user_type,
    ):
        user_id_obj = UserID.from_string(user_id)

        now = int(self.clock.time())

        next_id = self._access_tokens_id_gen.get_next()

        try:
            if was_guest:
                # Ensure that the guest user actually exists
                # ``allow_none=False`` makes this raise an exception
                # if the row isn't in the database.
                self._simple_select_one_txn(
                    txn,
                    "users",
                    keyvalues={"name": user_id, "is_guest": 1},
                    retcols=("name",),
                    allow_none=False,
                )

                self._simple_update_one_txn(
                    txn,
                    "users",
                    keyvalues={"name": user_id, "is_guest": 1},
                    updatevalues={
                        "password_hash": password_hash,
                        "upgrade_ts": now,
                        "is_guest": 1 if make_guest else 0,
                        "appservice_id": appservice_id,
                        "admin": 1 if admin else 0,
                        "user_type": user_type,
                    },
                )
            else:
                self._simple_insert_txn(
                    txn,
                    "users",
                    values={
                        "name": user_id,
                        "password_hash": password_hash,
                        "creation_ts": now,
                        "is_guest": 1 if make_guest else 0,
                        "appservice_id": appservice_id,
                        "admin": 1 if admin else 0,
                        "user_type": user_type,
                    },
                )

        except self.database_engine.module.IntegrityError:
            raise StoreError(400, "User ID already taken.", errcode=Codes.USER_IN_USE)

        if self._account_validity.enabled:
            self.set_expiration_date_for_user_txn(txn, user_id)

        if token:
            # it's possible for this to get a conflict, but only for a single user
            # since tokens are namespaced based on their user ID
            txn.execute(
                "INSERT INTO access_tokens(id, user_id, token)" " VALUES (?,?,?)",
                (next_id, user_id, token),
            )

        if create_profile_with_displayname:
            # set a default displayname serverside to avoid ugly race
            # between auto-joins and clients trying to set displaynames
            #
            # *obviously* the 'profiles' table uses localpart for user_id
            # while everything else uses the full mxid.
            txn.execute(
                "INSERT INTO profiles(user_id, displayname) VALUES (?,?)",
                (user_id_obj.localpart, create_profile_with_displayname),
            )

        self._invalidate_cache_and_stream(txn, self.get_user_by_id, (user_id,))
        txn.call_after(self.is_guest.invalidate, (user_id,))

    def user_set_password_hash(self, user_id, password_hash):
        """
        NB. This does *not* evict any cache because the one use for this
            removes most of the entries subsequently anyway so it would be
            pointless. Use flush_user separately.
        """

        def user_set_password_hash_txn(txn):
            self._simple_update_one_txn(
                txn, 'users', {'name': user_id}, {'password_hash': password_hash}
            )
            self._invalidate_cache_and_stream(txn, self.get_user_by_id, (user_id,))

        return self.runInteraction("user_set_password_hash", user_set_password_hash_txn)

    def user_set_consent_version(self, user_id, consent_version):
        """Updates the user table to record privacy policy consent

        Args:
            user_id (str): full mxid of the user to update
            consent_version (str): version of the policy the user has consented
                to

        Raises:
            StoreError(404) if user not found
        """

        def f(txn):
            self._simple_update_one_txn(
                txn,
                table='users',
                keyvalues={'name': user_id},
                updatevalues={'consent_version': consent_version},
            )
            self._invalidate_cache_and_stream(txn, self.get_user_by_id, (user_id,))

        return self.runInteraction("user_set_consent_version", f)

    def user_set_consent_server_notice_sent(self, user_id, consent_version):
        """Updates the user table to record that we have sent the user a server
        notice about privacy policy consent

        Args:
            user_id (str): full mxid of the user to update
            consent_version (str): version of the policy we have notified the
                user about

        Raises:
            StoreError(404) if user not found
        """

        def f(txn):
            self._simple_update_one_txn(
                txn,
                table='users',
                keyvalues={'name': user_id},
                updatevalues={'consent_server_notice_sent': consent_version},
            )
            self._invalidate_cache_and_stream(txn, self.get_user_by_id, (user_id,))

        return self.runInteraction("user_set_consent_server_notice_sent", f)

    def user_delete_access_tokens(self, user_id, except_token_id=None, device_id=None):
        """
        Invalidate access tokens belonging to a user

        Args:
            user_id (str):  ID of user the tokens belong to
            except_token_id (str): list of access_tokens IDs which should
                *not* be deleted
            device_id (str|None):  ID of device the tokens are associated with.
                If None, tokens associated with any device (or no device) will
                be deleted
        Returns:
            defer.Deferred[list[str, int, str|None, int]]: a list of
                (token, token id, device id) for each of the deleted tokens
        """

        def f(txn):
            keyvalues = {"user_id": user_id}
            if device_id is not None:
                keyvalues["device_id"] = device_id

            items = keyvalues.items()
            where_clause = " AND ".join(k + " = ?" for k, _ in items)
            values = [v for _, v in items]
            if except_token_id:
                where_clause += " AND id != ?"
                values.append(except_token_id)

            txn.execute(
                "SELECT token, id, device_id FROM access_tokens WHERE %s"
                % where_clause,
                values,
            )
            tokens_and_devices = [(r[0], r[1], r[2]) for r in txn]

            for token, _, _ in tokens_and_devices:
                self._invalidate_cache_and_stream(
                    txn, self.get_user_by_access_token, (token,)
                )

            txn.execute("DELETE FROM access_tokens WHERE %s" % where_clause, values)

            return tokens_and_devices

        return self.runInteraction("user_delete_access_tokens", f)

    def delete_access_token(self, access_token):
        def f(txn):
            self._simple_delete_one_txn(
                txn, table="access_tokens", keyvalues={"token": access_token}
            )

            self._invalidate_cache_and_stream(
                txn, self.get_user_by_access_token, (access_token,)
            )

        return self.runInteraction("delete_access_token", f)

    @cachedInlineCallbacks()
    def is_guest(self, user_id):
        res = yield self._simple_select_one_onecol(
            table="users",
            keyvalues={"name": user_id},
            retcol="is_guest",
            allow_none=True,
            desc="is_guest",
        )

        defer.returnValue(res if res else False)

    @defer.inlineCallbacks
    def save_or_get_3pid_guest_access_token(
        self, medium, address, access_token, inviter_user_id
    ):
        """
        Gets the 3pid's guest access token if exists, else saves access_token.

        Args:
            medium (str): Medium of the 3pid. Must be "email".
            address (str): 3pid address.
            access_token (str): The access token to persist if none is
                already persisted.
            inviter_user_id (str): User ID of the inviter.

        Returns:
            deferred str: Whichever access token is persisted at the end
            of this function call.
        """

        def insert(txn):
            txn.execute(
                "INSERT INTO threepid_guest_access_tokens "
                "(medium, address, guest_access_token, first_inviter) "
                "VALUES (?, ?, ?, ?)",
                (medium, address, access_token, inviter_user_id),
            )

        try:
            yield self.runInteraction("save_3pid_guest_access_token", insert)
            defer.returnValue(access_token)
        except self.database_engine.module.IntegrityError:
            ret = yield self.get_3pid_guest_access_token(medium, address)
            defer.returnValue(ret)

    def add_user_pending_deactivation(self, user_id):
        """
        Adds a user to the table of users who need to be parted from all the rooms they're
        in
        """
        return self._simple_insert(
            "users_pending_deactivation",
            values={"user_id": user_id},
            desc="add_user_pending_deactivation",
        )

    def del_user_pending_deactivation(self, user_id):
        """
        Removes the given user to the table of users who need to be parted from all the
        rooms they're in, effectively marking that user as fully deactivated.
        """
        # XXX: This should be simple_delete_one but we failed to put a unique index on
        # the table, so somehow duplicate entries have ended up in it.
        return self._simple_delete(
            "users_pending_deactivation",
            keyvalues={"user_id": user_id},
            desc="del_user_pending_deactivation",
        )

    def get_user_pending_deactivation(self):
        """
        Gets one user from the table of users waiting to be parted from all the rooms
        they're in.
        """
        return self._simple_select_one_onecol(
            "users_pending_deactivation",
            keyvalues={},
            retcol="user_id",
            allow_none=True,
            desc="get_users_pending_deactivation",
        )

    @defer.inlineCallbacks
    def _bg_user_threepids_grandfather(self, progress, batch_size):
        """We now track which identity servers a user binds their 3PID to, so
        we need to handle the case of existing bindings where we didn't track
        this.

        We do this by grandfathering in existing user threepids assuming that
        they used one of the server configured trusted identity servers.
        """
        id_servers = set(self.config.trusted_third_party_id_servers)

        def _bg_user_threepids_grandfather_txn(txn):
            sql = """
                INSERT INTO user_threepid_id_server
                    (user_id, medium, address, id_server)
                SELECT user_id, medium, address, ?
                FROM user_threepids
            """

            txn.executemany(sql, [(id_server,) for id_server in id_servers])

        if id_servers:
            yield self.runInteraction(
                "_bg_user_threepids_grandfather", _bg_user_threepids_grandfather_txn,
            )

        yield self._end_background_update("user_threepids_grandfather")

        defer.returnValue(1)

    def get_threepid_validation_session(
        self,
        medium,
        client_secret,
        address=None,
        sid=None,
        validated=None,
    ):
        """Gets a session_id and last_send_attempt (if available) for a
        client_secret/medium/(address|session_id) combo

        Args:
            medium (str|None): The medium of the 3PID
            address (str|None): The address of the 3PID
            sid (str|None): The ID of the validation session
            client_secret (str|None): A unique string provided by the client to
                help identify this validation attempt
            validated (bool|None): Whether sessions should be filtered by
                whether they have been validated already or not. None to
                perform no filtering

        Returns:
            deferred {str, int}|None: A dict containing the
                latest session_id and send_attempt count for this 3PID.
                Otherwise None if there hasn't been a previous attempt
        """
        keyvalues = {
            "medium": medium,
            "client_secret": client_secret,
        }
        if address:
            keyvalues["address"] = address
        if sid:
            keyvalues["session_id"] = sid

        assert(address or sid)

        def get_threepid_validation_session_txn(txn):
            sql = """
                SELECT address, session_id, medium, client_secret,
                last_send_attempt, validated_at
                FROM threepid_validation_session WHERE %s
                """ % (" AND ".join("%s = ?" % k for k in iterkeys(keyvalues)),)

            if validated is not None:
                sql += " AND validated_at IS " + ("NOT NULL" if validated else "NULL")

            sql += " LIMIT 1"

            txn.execute(sql, list(keyvalues.values()))
            rows = self.cursor_to_dict(txn)
            if not rows:
                return None

            return rows[0]

        return self.runInteraction(
            "get_threepid_validation_session",
            get_threepid_validation_session_txn,
        )

    def validate_threepid_session(
        self,
        session_id,
        client_secret,
        token,
        current_ts,
    ):
        """Attempt to validate a threepid session using a token

        Args:
            session_id (str): The id of a validation session
            client_secret (str): A unique string provided by the client to
                help identify this validation attempt
            token (str): A validation token
            current_ts (int): The current unix time in milliseconds. Used for
                checking token expiry status

        Returns:
            deferred str|None: A str representing a link to redirect the user
            to if there is one.
        """
        # Insert everything into a transaction in order to run atomically
        def validate_threepid_session_txn(txn):
            row = self._simple_select_one_txn(
                txn,
                table="threepid_validation_session",
                keyvalues={"session_id": session_id},
                retcols=["client_secret", "validated_at"],
                allow_none=True,
            )

            if not row:
                raise ThreepidValidationError(400, "Unknown session_id")
            retrieved_client_secret = row["client_secret"]
            validated_at = row["validated_at"]

            if retrieved_client_secret != client_secret:
                raise ThreepidValidationError(
                    400, "This client_secret does not match the provided session_id",
                )

            row = self._simple_select_one_txn(
                txn,
                table="threepid_validation_token",
                keyvalues={"session_id": session_id, "token": token},
                retcols=["expires", "next_link"],
                allow_none=True,
            )

            if not row:
                raise ThreepidValidationError(
                    400, "Validation token not found or has expired",
                )
            expires = row["expires"]
            next_link = row["next_link"]

            # If the session is already validated, no need to revalidate
            if validated_at:
                return next_link

            if expires <= current_ts:
                raise ThreepidValidationError(
                    400, "This token has expired. Please request a new one",
                )

            # Looks good. Validate the session
            self._simple_update_txn(
                txn,
                table="threepid_validation_session",
                keyvalues={"session_id": session_id},
                updatevalues={"validated_at": self.clock.time_msec()},
            )

            return next_link

        # Return next_link if it exists
        return self.runInteraction(
            "validate_threepid_session_txn",
            validate_threepid_session_txn,
        )

    def upsert_threepid_validation_session(
        self,
        medium,
        address,
        client_secret,
        send_attempt,
        session_id,
        validated_at=None,
    ):
        """Upsert a threepid validation session
        Args:
            medium (str): The medium of the 3PID
            address (str): The address of the 3PID
            client_secret (str): A unique string provided by the client to
                help identify this validation attempt
            send_attempt (int): The latest send_attempt on this session
            session_id (str): The id of this validation session
            validated_at (int|None): The unix timestamp in milliseconds of
                when the session was marked as valid
        """
        insertion_values = {
            "medium": medium,
            "address": address,
            "client_secret": client_secret,
        }

        if validated_at:
            insertion_values["validated_at"] = validated_at

        return self._simple_upsert(
            table="threepid_validation_session",
            keyvalues={"session_id": session_id},
            values={"last_send_attempt": send_attempt},
            insertion_values=insertion_values,
            desc="upsert_threepid_validation_session",
        )

    def start_or_continue_validation_session(
        self,
        medium,
        address,
        session_id,
        client_secret,
        send_attempt,
        next_link,
        token,
        token_expires,
    ):
        """Creates a new threepid validation session if it does not already
        exist and associates a new validation token with it

        Args:
            medium (str): The medium of the 3PID
            address (str): The address of the 3PID
            session_id (str): The id of this validation session
            client_secret (str): A unique string provided by the client to
                help identify this validation attempt
            send_attempt (int): The latest send_attempt on this session
            next_link (str|None): The link to redirect the user to upon
                successful validation
            token (str): The validation token
            token_expires (int): The timestamp for which after the token
                will no longer be valid
        """
        def start_or_continue_validation_session_txn(txn):
            # Create or update a validation session
            self._simple_upsert_txn(
                txn,
                table="threepid_validation_session",
                keyvalues={"session_id": session_id},
                values={"last_send_attempt": send_attempt},
                insertion_values={
                    "medium": medium,
                    "address": address,
                    "client_secret": client_secret,
                },
            )

            # Create a new validation token with this session ID
            self._simple_insert_txn(
                txn,
                table="threepid_validation_token",
                values={
                    "session_id": session_id,
                    "token": token,
                    "next_link": next_link,
                    "expires": token_expires,
                },
            )

        return self.runInteraction(
            "start_or_continue_validation_session",
            start_or_continue_validation_session_txn,
        )

    def cull_expired_threepid_validation_tokens(self):
        """Remove threepid validation tokens with expiry dates that have passed"""
        def cull_expired_threepid_validation_tokens_txn(txn, ts):
            sql = """
            DELETE FROM threepid_validation_token WHERE
            expires < ?
            """
            return txn.execute(sql, (ts,))

        return self.runInteraction(
            "cull_expired_threepid_validation_tokens",
            cull_expired_threepid_validation_tokens_txn,
            self.clock.time_msec(),
        )

    def delete_threepid_session(self, session_id):
        """Removes a threepid validation session from the database. This can
        be done after validation has been performed and whatever action was
        waiting on it has been carried out

        Args:
            session_id (str): The ID of the session to delete
        """
        def delete_threepid_session_txn(txn):
            self._simple_delete_txn(
                txn,
                table="threepid_validation_token",
                keyvalues={"session_id": session_id},
            )
            self._simple_delete_txn(
                txn,
                table="threepid_validation_session",
                keyvalues={"session_id": session_id},
            )

        return self.runInteraction(
            "delete_threepid_session",
            delete_threepid_session_txn,
        )