path: root/synapse/config/server.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 logging
import os.path
import re
from textwrap import indent

import attr
import yaml
from netaddr import IPSet

from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
from synapse.http.endpoint import parse_and_validate_server_name
from synapse.python_dependencies import DependencyException, check_requirements

from ._base import Config, ConfigError

logger = logging.Logger(__name__)

# by default, we attempt to listen on both '::' *and* '0.0.0.0' because some OSes
# (Windows, macOS, other BSD/Linux where net.ipv6.bindv6only is set) will only listen
# on IPv6 when '::' is set.
#
# We later check for errors when binding to 0.0.0.0 and ignore them if :: is also in
# in the list.
DEFAULT_BIND_ADDRESSES = ["::", "0.0.0.0"]

DEFAULT_ROOM_VERSION = "4"

ROOM_COMPLEXITY_TOO_GREAT = (
    "Your homeserver is unable to join rooms this large or complex. "
    "Please speak to your server administrator, or upgrade your instance "
    "to join this room."
)


class ServerConfig(Config):
    def read_config(self, config, **kwargs):
        self.server_name = config["server_name"]
        self.server_context = config.get("server_context", None)

        try:
            parse_and_validate_server_name(self.server_name)
        except ValueError as e:
            raise ConfigError(str(e))

        self.pid_file = self.abspath(config.get("pid_file"))
        self.web_client_location = config.get("web_client_location", None)
        self.soft_file_limit = config.get("soft_file_limit", 0)
        self.daemonize = config.get("daemonize")
        self.print_pidfile = config.get("print_pidfile")
        self.user_agent_suffix = config.get("user_agent_suffix")
        self.use_frozen_dicts = config.get("use_frozen_dicts", False)
        self.public_baseurl = config.get("public_baseurl")

        # Whether to send federation traffic out in this process. This only
        # applies to some federation traffic, and so shouldn't be used to
        # "disable" federation
        self.send_federation = config.get("send_federation", True)

        # Whether to enable user presence.
        self.use_presence = config.get("use_presence", True)

        # Whether to update the user directory or not. This should be set to
        # false only if we are updating the user directory in a worker
        self.update_user_directory = config.get("update_user_directory", True)

        # whether to enable the media repository endpoints. This should be set
        # to false if the media repository is running as a separate endpoint;
        # doing so ensures that we will not run cache cleanup jobs on the
        # master, potentially causing inconsistency.
        self.enable_media_repo = config.get("enable_media_repo", True)

        # Whether to require authentication to retrieve profile data (avatars,
        # display names) of other users through the client API.
        self.require_auth_for_profile_requests = config.get(
            "require_auth_for_profile_requests", False
        )

        if "restrict_public_rooms_to_local_users" in config and (
            "allow_public_rooms_without_auth" in config
            or "allow_public_rooms_over_federation" in config
        ):
            raise ConfigError(
                "Can't use 'restrict_public_rooms_to_local_users' if"
                " 'allow_public_rooms_without_auth' and/or"
                " 'allow_public_rooms_over_federation' is set."
            )

        # Check if the legacy "restrict_public_rooms_to_local_users" flag is set. This
        # flag is now obsolete but we need to check it for backward-compatibility.
        if config.get("restrict_public_rooms_to_local_users", False):
            self.allow_public_rooms_without_auth = False
            self.allow_public_rooms_over_federation = False
        else:
            # If set to 'False', requires authentication to access the server's public
            # rooms directory through the client API. Defaults to 'True'.
            self.allow_public_rooms_without_auth = config.get(
                "allow_public_rooms_without_auth", True
            )
            # If set to 'False', forbids any other homeserver to fetch the server's public
            # rooms directory via federation. Defaults to 'True'.
            self.allow_public_rooms_over_federation = config.get(
                "allow_public_rooms_over_federation", True
            )

        default_room_version = config.get("default_room_version", DEFAULT_ROOM_VERSION)

        # Ensure room version is a str
        default_room_version = str(default_room_version)

        if default_room_version not in KNOWN_ROOM_VERSIONS:
            raise ConfigError(
                "Unknown default_room_version: %s, known room versions: %s"
                % (default_room_version, list(KNOWN_ROOM_VERSIONS.keys()))
            )

        # Get the actual room version object rather than just the identifier
        self.default_room_version = KNOWN_ROOM_VERSIONS[default_room_version]

        # whether to enable search. If disabled, new entries will not be inserted
        # into the search tables and they will not be indexed. Users will receive
        # errors when attempting to search for messages.
        self.enable_search = config.get("enable_search", True)

        self.filter_timeline_limit = config.get("filter_timeline_limit", -1)

        # Whether we should block invites sent to users on this server
        # (other than those sent by local server admins)
        self.block_non_admin_invites = config.get("block_non_admin_invites", False)

        # Whether to enable experimental MSC1849 (aka relations) support
        self.experimental_msc1849_support_enabled = config.get(
            "experimental_msc1849_support_enabled", True
        )

        # Options to control access by tracking MAU
        self.limit_usage_by_mau = config.get("limit_usage_by_mau", False)
        self.max_mau_value = 0
        if self.limit_usage_by_mau:
            self.max_mau_value = config.get("max_mau_value", 0)
        self.mau_stats_only = config.get("mau_stats_only", False)

        self.mau_limits_reserved_threepids = config.get(
            "mau_limit_reserved_threepids", []
        )

        self.mau_trial_days = config.get("mau_trial_days", 0)

        # How long to keep redacted events in the database in unredacted form
        # before redacting them.
        redaction_retention_period = config.get("redaction_retention_period")
        if redaction_retention_period:
            self.redaction_retention_period = self.parse_duration(
                redaction_retention_period
            )
        else:
            self.redaction_retention_period = None

        # Options to disable HS
        self.hs_disabled = config.get("hs_disabled", False)
        self.hs_disabled_message = config.get("hs_disabled_message", "")
        self.hs_disabled_limit_type = config.get("hs_disabled_limit_type", "")

        # Admin uri to direct users at should their instance become blocked
        # due to resource constraints
        self.admin_contact = config.get("admin_contact", None)

        # FIXME: federation_domain_whitelist needs sytests
        self.federation_domain_whitelist = None
        federation_domain_whitelist = config.get("federation_domain_whitelist", None)

        if federation_domain_whitelist is not None:
            # turn the whitelist into a hash for speed of lookup
            self.federation_domain_whitelist = {}

            for domain in federation_domain_whitelist:
                self.federation_domain_whitelist[domain] = True

        self.federation_ip_range_blacklist = config.get(
            "federation_ip_range_blacklist", []
        )

        # Attempt to create an IPSet from the given ranges
        try:
            self.federation_ip_range_blacklist = IPSet(
                self.federation_ip_range_blacklist
            )

            # Always blacklist 0.0.0.0, ::
            self.federation_ip_range_blacklist.update(["0.0.0.0", "::"])
        except Exception as e:
            raise ConfigError(
                "Invalid range(s) provided in " "federation_ip_range_blacklist: %s" % e
            )

        if self.public_baseurl is not None:
            if self.public_baseurl[-1] != "/":
                self.public_baseurl += "/"
        self.start_pushers = config.get("start_pushers", True)

        # (undocumented) option for torturing the worker-mode replication a bit,
        # for testing. The value defines the number of milliseconds to pause before
        # sending out any replication updates.
        self.replication_torture_level = config.get("replication_torture_level")

        # Whether to require a user to be in the room to add an alias to it.
        # Defaults to True.
        self.require_membership_for_aliases = config.get(
            "require_membership_for_aliases", True
        )

        # Whether to allow per-room membership profiles through the send of membership
        # events with profile information that differ from the target's global profile.
        self.allow_per_room_profiles = config.get("allow_per_room_profiles", True)

        self.listeners = []
        for listener in config.get("listeners", []):
            if not isinstance(listener.get("port", None), int):
                raise ConfigError(
                    "Listener configuration is lacking a valid 'port' option"
                )

            if listener.setdefault("tls", False):
                # no_tls is not really supported any more, but let's grandfather it in
                # here.
                if config.get("no_tls", False):
                    logger.info(
                        "Ignoring TLS-enabled listener on port %i due to no_tls"
                    )
                    continue

            bind_address = listener.pop("bind_address", None)
            bind_addresses = listener.setdefault("bind_addresses", [])

            # if bind_address was specified, add it to the list of addresses
            if bind_address:
                bind_addresses.append(bind_address)

            # if we still have an empty list of addresses, use the default list
            if not bind_addresses:
                if listener["type"] == "metrics":
                    # the metrics listener doesn't support IPv6
                    bind_addresses.append("0.0.0.0")
                else:
                    bind_addresses.extend(DEFAULT_BIND_ADDRESSES)

            self.listeners.append(listener)

        if not self.web_client_location:
            _warn_if_webclient_configured(self.listeners)

        self.gc_thresholds = read_gc_thresholds(config.get("gc_thresholds", None))

        @attr.s
        class LimitRemoteRoomsConfig(object):
            enabled = attr.ib(
                validator=attr.validators.instance_of(bool), default=False
            )
            complexity = attr.ib(
                validator=attr.validators.instance_of((int, float)), default=1.0
            )
            complexity_error = attr.ib(
                validator=attr.validators.instance_of(str),
                default=ROOM_COMPLEXITY_TOO_GREAT,
            )

        self.limit_remote_rooms = LimitRemoteRoomsConfig(
            **config.get("limit_remote_rooms", {})
        )

        bind_port = config.get("bind_port")
        if bind_port:
            if config.get("no_tls", False):
                raise ConfigError("no_tls is incompatible with bind_port")

            self.listeners = []
            bind_host = config.get("bind_host", "")
            gzip_responses = config.get("gzip_responses", True)

            self.listeners.append(
                {
                    "port": bind_port,
                    "bind_addresses": [bind_host],
                    "tls": True,
                    "type": "http",
                    "resources": [
                        {"names": ["client"], "compress": gzip_responses},
                        {"names": ["federation"], "compress": False},
                    ],
                }
            )

            unsecure_port = config.get("unsecure_port", bind_port - 400)
            if unsecure_port:
                self.listeners.append(
                    {
                        "port": unsecure_port,
                        "bind_addresses": [bind_host],
                        "tls": False,
                        "type": "http",
                        "resources": [
                            {"names": ["client"], "compress": gzip_responses},
                            {"names": ["federation"], "compress": False},
                        ],
                    }
                )

        manhole = config.get("manhole")
        if manhole:
            self.listeners.append(
                {
                    "port": manhole,
                    "bind_addresses": ["127.0.0.1"],
                    "type": "manhole",
                    "tls": False,
                }
            )

        metrics_port = config.get("metrics_port")
        if metrics_port:
            logger.warn(
                (
                    "The metrics_port configuration option is deprecated in Synapse 0.31 "
                    "in favour of a listener. Please see "
                    "http://github.com/matrix-org/synapse/blob/master/docs/metrics-howto.rst"
                    " on how to configure the new listener."
                )
            )

            self.listeners.append(
                {
                    "port": metrics_port,
                    "bind_addresses": [config.get("metrics_bind_host", "127.0.0.1")],
                    "tls": False,
                    "type": "http",
                    "resources": [{"names": ["metrics"], "compress": False}],
                }
            )

        _check_resource_config(self.listeners)

        # An experimental option to try and periodically clean up extremities
        # by sending dummy events.
        self.cleanup_extremities_with_dummy_events = config.get(
            "cleanup_extremities_with_dummy_events", False
        )

    def has_tls_listener(self):
        return any(l["tls"] for l in self.listeners)

    def generate_config_section(
        self, server_name, data_dir_path, open_private_ports, listeners, **kwargs
    ):
        _, bind_port = parse_and_validate_server_name(server_name)
        if bind_port is not None:
            unsecure_port = bind_port - 400
        else:
            bind_port = 8448
            unsecure_port = 8008

        pid_file = os.path.join(data_dir_path, "homeserver.pid")

        # Bring DEFAULT_ROOM_VERSION into the local-scope for use in the
        # default config string
        default_room_version = DEFAULT_ROOM_VERSION
        secure_listeners = []
        unsecure_listeners = []
        private_addresses = ["::1", "127.0.0.1"]
        if listeners:
            for listener in listeners:
                if listener["tls"]:
                    secure_listeners.append(listener)
                else:
                    # If we don't want open ports we need to bind the listeners
                    # to some address other than 0.0.0.0. Here we chose to use
                    # localhost.
                    # If the addresses are already bound we won't overwrite them
                    # however.
                    if not open_private_ports:
                        listener.setdefault("bind_addresses", private_addresses)

                    unsecure_listeners.append(listener)

            secure_http_bindings = indent(
                yaml.dump(secure_listeners), " " * 10
            ).lstrip()

            unsecure_http_bindings = indent(
                yaml.dump(unsecure_listeners), " " * 10
            ).lstrip()

        if not unsecure_listeners:
            unsecure_http_bindings = (
                """- port: %(unsecure_port)s
            tls: false
            type: http
            x_forwarded: true"""
                % locals()
            )

            if not open_private_ports:
                unsecure_http_bindings += (
                    "\n            bind_addresses: ['::1', '127.0.0.1']"
                )

            unsecure_http_bindings += """

            resources:
              - names: [client, federation]
                compress: false"""

            if listeners:
                # comment out this block
                unsecure_http_bindings = "#" + re.sub(
                    "\n {10}",
                    lambda match: match.group(0) + "#",
                    unsecure_http_bindings,
                )

        if not secure_listeners:
            secure_http_bindings = (
                """#- port: %(bind_port)s
          #  type: http
          #  tls: true
          #  resources:
          #    - names: [client, federation]"""
                % locals()
            )

        return (
            """\
        ## Server ##

        # The domain name of the server, with optional explicit port.
        # This is used by remote servers to connect to this server,
        # e.g. matrix.org, localhost:8080, etc.
        # This is also the last part of your UserID.
        #
        server_name: "%(server_name)s"

        # When running as a daemon, the file to store the pid in
        #
        pid_file: %(pid_file)s

        # The path to the web client which will be served at /_matrix/client/
        # if 'webclient' is configured under the 'listeners' configuration.
        #
        #web_client_location: "/path/to/web/root"

        # The public-facing base URL that clients use to access this HS
        # (not including _matrix/...). This is the same URL a user would
        # enter into the 'custom HS URL' field on their client. If you
        # use synapse with a reverse proxy, this should be the URL to reach
        # synapse via the proxy.
        #
        #public_baseurl: https://example.com/

        # Set the soft limit on the number of file descriptors synapse can use
        # Zero is used to indicate synapse should set the soft limit to the
        # hard limit.
        #
        #soft_file_limit: 0

        # Set to false to disable presence tracking on this homeserver.
        #
        #use_presence: false

        # Whether to require authentication to retrieve profile data (avatars,
        # display names) of other users through the client API. Defaults to
        # 'false'. Note that profile data is also available via the federation
        # API, so this setting is of limited value if federation is enabled on
        # the server.
        #
        #require_auth_for_profile_requests: true

        # If set to 'false', requires authentication to access the server's public rooms
        # directory through the client API. Defaults to 'true'.
        #
        #allow_public_rooms_without_auth: false

        # If set to 'false', forbids any other homeserver to fetch the server's public
        # rooms directory via federation. Defaults to 'true'.
        #
        #allow_public_rooms_over_federation: false

        # The default room version for newly created rooms.
        #
        # Known room versions are listed here:
        # https://matrix.org/docs/spec/#complete-list-of-room-versions
        #
        # For example, for room version 1, default_room_version should be set
        # to "1".
        #
        #default_room_version: "%(default_room_version)s"

        # The GC threshold parameters to pass to `gc.set_threshold`, if defined
        #
        #gc_thresholds: [700, 10, 10]

        # Set the limit on the returned events in the timeline in the get
        # and sync operations. The default value is -1, means no upper limit.
        #
        #filter_timeline_limit: 5000

        # Whether room invites to users on this server should be blocked
        # (except those sent by local server admins). The default is False.
        #
        #block_non_admin_invites: True

        # Room searching
        #
        # If disabled, new messages will not be indexed for searching and users
        # will receive errors when searching for messages. Defaults to enabled.
        #
        #enable_search: false

        # Restrict federation to the following whitelist of domains.
        # N.B. we recommend also firewalling your federation listener to limit
        # inbound federation traffic as early as possible, rather than relying
        # purely on this application-layer restriction.  If not specified, the
        # default is to whitelist everything.
        #
        #federation_domain_whitelist:
        #  - lon.example.com
        #  - nyc.example.com
        #  - syd.example.com

        # Prevent federation requests from being sent to the following
        # blacklist IP address CIDR ranges. If this option is not specified, or
        # specified with an empty list, no ip range blacklist will be enforced.
        #
        # (0.0.0.0 and :: are always blacklisted, whether or not they are explicitly
        # listed here, since they correspond to unroutable addresses.)
        #
        federation_ip_range_blacklist:
          - '127.0.0.0/8'
          - '10.0.0.0/8'
          - '172.16.0.0/12'
          - '192.168.0.0/16'
          - '100.64.0.0/10'
          - '169.254.0.0/16'
          - '::1/128'
          - 'fe80::/64'
          - 'fc00::/7'

        # List of ports that Synapse should listen on, their purpose and their
        # configuration.
        #
        # Options for each listener include:
        #
        #   port: the TCP port to bind to
        #
        #   bind_addresses: a list of local addresses to listen on. The default is
        #       'all local interfaces'.
        #
        #   type: the type of listener. Normally 'http', but other valid options are:
        #       'manhole' (see docs/manhole.md),
        #       'metrics' (see docs/metrics-howto.rst),
        #       'replication' (see docs/workers.rst).
        #
        #   tls: set to true to enable TLS for this listener. Will use the TLS
        #       key/cert specified in tls_private_key_path / tls_certificate_path.
        #
        #   x_forwarded: Only valid for an 'http' listener. Set to true to use the
        #       X-Forwarded-For header as the client IP. Useful when Synapse is
        #       behind a reverse-proxy.
        #
        #   resources: Only valid for an 'http' listener. A list of resources to host
        #       on this port. Options for each resource are:
        #
        #       names: a list of names of HTTP resources. See below for a list of
        #           valid resource names.
        #
        #       compress: set to true to enable HTTP comression for this resource.
        #
        #   additional_resources: Only valid for an 'http' listener. A map of
        #        additional endpoints which should be loaded via dynamic modules.
        #
        # Valid resource names are:
        #
        #   client: the client-server API (/_matrix/client), and the synapse admin
        #       API (/_synapse/admin). Also implies 'media' and 'static'.
        #
        #   consent: user consent forms (/_matrix/consent). See
        #       docs/consent_tracking.md.
        #
        #   federation: the server-server API (/_matrix/federation). Also implies
        #       'media', 'keys', 'openid'
        #
        #   keys: the key discovery API (/_matrix/keys).
        #
        #   media: the media API (/_matrix/media).
        #
        #   metrics: the metrics interface. See docs/metrics-howto.rst.
        #
        #   openid: OpenID authentication.
        #
        #   replication: the HTTP replication API (/_synapse/replication). See
        #       docs/workers.rst.
        #
        #   static: static resources under synapse/static (/_matrix/static). (Mostly
        #       useful for 'fallback authentication'.)
        #
        #   webclient: A web client. Requires web_client_location to be set.
        #
        listeners:
          # TLS-enabled listener: for when matrix traffic is sent directly to synapse.
          #
          # Disabled by default. To enable it, uncomment the following. (Note that you
          # will also need to give Synapse a TLS key and certificate: see the TLS section
          # below.)
          #
          %(secure_http_bindings)s

          # Unsecure HTTP listener: for when matrix traffic passes through a reverse proxy
          # that unwraps TLS.
          #
          # If you plan to use a reverse proxy, please see
          # https://github.com/matrix-org/synapse/blob/master/docs/reverse_proxy.rst.
          #
          %(unsecure_http_bindings)s

            # example additional_resources:
            #
            #additional_resources:
            #  "/_matrix/my/custom/endpoint":
            #    module: my_module.CustomRequestHandler
            #    config: {}

          # Turn on the twisted ssh manhole service on localhost on the given
          # port.
          #
          #- port: 9000
          #  bind_addresses: ['::1', '127.0.0.1']
          #  type: manhole


        ## Homeserver blocking ##

        # How to reach the server admin, used in ResourceLimitError
        #
        #admin_contact: 'mailto:admin@server.com'

        # Global blocking
        #
        #hs_disabled: False
        #hs_disabled_message: 'Human readable reason for why the HS is blocked'
        #hs_disabled_limit_type: 'error code(str), to help clients decode reason'

        # Monthly Active User Blocking
        #
        # Used in cases where the admin or server owner wants to limit to the
        # number of monthly active users.
        #
        # 'limit_usage_by_mau' disables/enables monthly active user blocking. When
        # anabled and a limit is reached the server returns a 'ResourceLimitError'
        # with error type Codes.RESOURCE_LIMIT_EXCEEDED
        #
        # 'max_mau_value' is the hard limit of monthly active users above which
        # the server will start blocking user actions.
        #
        # 'mau_trial_days' is a means to add a grace period for active users. It
        # means that users must be active for this number of days before they
        # can be considered active and guards against the case where lots of users
        # sign up in a short space of time never to return after their initial
        # session.
        #
        #limit_usage_by_mau: False
        #max_mau_value: 50
        #mau_trial_days: 2

        # If enabled, the metrics for the number of monthly active users will
        # be populated, however no one will be limited. If limit_usage_by_mau
        # is true, this is implied to be true.
        #
        #mau_stats_only: False

        # Sometimes the server admin will want to ensure certain accounts are
        # never blocked by mau checking. These accounts are specified here.
        #
        #mau_limit_reserved_threepids:
        #  - medium: 'email'
        #    address: 'reserved_user@example.com'

        # Used by phonehome stats to group together related servers.
        #server_context: context

        # Resource-constrained Homeserver Settings
        #
        # If limit_remote_rooms.enabled is True, the room complexity will be
        # checked before a user joins a new remote room. If it is above
        # limit_remote_rooms.complexity, it will disallow joining or
        # instantly leave.
        #
        # limit_remote_rooms.complexity_error can be set to customise the text
        # displayed to the user when a room above the complexity threshold has
        # its join cancelled.
        #
        # Uncomment the below lines to enable:
        #limit_remote_rooms:
        #  enabled: True
        #  complexity: 1.0
        #  complexity_error: "This room is too complex."

        # Whether to require a user to be in the room to add an alias to it.
        # Defaults to 'true'.
        #
        #require_membership_for_aliases: false

        # Whether to allow per-room membership profiles through the send of membership
        # events with profile information that differ from the target's global profile.
        # Defaults to 'true'.
        #
        #allow_per_room_profiles: false

        # How long to keep redacted events in unredacted form in the database.
        # By default redactions are kept indefinitely.
        #
        #redaction_retention_period: 30d
        """
            % locals()
        )

    def read_arguments(self, args):
        if args.manhole is not None:
            self.manhole = args.manhole
        if args.daemonize is not None:
            self.daemonize = args.daemonize
        if args.print_pidfile is not None:
            self.print_pidfile = args.print_pidfile

    @staticmethod
    def add_arguments(parser):
        server_group = parser.add_argument_group("server")
        server_group.add_argument(
            "-D",
            "--daemonize",
            action="store_true",
            default=None,
            help="Daemonize the home server",
        )
        server_group.add_argument(
            "--print-pidfile",
            action="store_true",
            default=None,
            help="Print the path to the pidfile just" " before daemonizing",
        )
        server_group.add_argument(
            "--manhole",
            metavar="PORT",
            dest="manhole",
            type=int,
            help="Turn on the twisted telnet manhole" " service on the given port.",
        )


def is_threepid_reserved(reserved_threepids, threepid):
    """Check the threepid against the reserved threepid config
    Args:
        reserved_threepids([dict]) - list of reserved threepids
        threepid(dict) - The threepid to test for

    Returns:
        boolean Is the threepid undertest reserved_user
    """

    for tp in reserved_threepids:
        if threepid["medium"] == tp["medium"] and threepid["address"] == tp["address"]:
            return True
    return False


def read_gc_thresholds(thresholds):
    """Reads the three integer thresholds for garbage collection. Ensures that
    the thresholds are integers if thresholds are supplied.
    """
    if thresholds is None:
        return None
    try:
        assert len(thresholds) == 3
        return (int(thresholds[0]), int(thresholds[1]), int(thresholds[2]))
    except Exception:
        raise ConfigError(
            "Value of `gc_threshold` must be a list of three integers if set"
        )


NO_MORE_WEB_CLIENT_WARNING = """
Synapse no longer includes a web client. To enable a web client, configure
web_client_location. To remove this warning, remove 'webclient' from the 'listeners'
configuration.
"""


def _warn_if_webclient_configured(listeners):
    for listener in listeners:
        for res in listener.get("resources", []):
            for name in res.get("names", []):
                if name == "webclient":
                    logger.warning(NO_MORE_WEB_CLIENT_WARNING)
                    return


KNOWN_RESOURCES = (
    "client",
    "consent",
    "federation",
    "keys",
    "media",
    "metrics",
    "openid",
    "replication",
    "static",
    "webclient",
)


def _check_resource_config(listeners):
    resource_names = set(
        res_name
        for listener in listeners
        for res in listener.get("resources", [])
        for res_name in res.get("names", [])
    )

    for resource in resource_names:
        if resource not in KNOWN_RESOURCES:
            raise ConfigError("Unknown listener resource '%s'" % (resource,))
        if resource == "consent":
            try:
                check_requirements("resources.consent")
            except DependencyException as e:
                raise ConfigError(e.message)