Infrastructure for a server notices room

Server Notices use a special room which the user can't dismiss. They are
created on demand when some other bit of the code calls send_notice.

(This doesn't actually do much yet becuse we don't call send_notice anywhere)

9 files changed, 280 insertions, 7 deletions

diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index fb6bd3b421..1dea2ad024 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -38,6 +38,7 @@ from .spam_checker import SpamCheckerConfig
 from .groups import GroupsConfig
 from .user_directory import UserDirectoryConfig
 from .consent_config import ConsentConfig
+from .server_notices_config import ServerNoticesConfig
 
 
 class HomeServerConfig(TlsConfig, ServerConfig, DatabaseConfig, LoggingConfig,
@@ -47,7 +48,9 @@ class HomeServerConfig(TlsConfig, ServerConfig, DatabaseConfig, LoggingConfig,
                        JWTConfig, PasswordConfig, EmailConfig,
                        WorkerConfig, PasswordAuthProviderConfig, PushConfig,
                        SpamCheckerConfig, GroupsConfig, UserDirectoryConfig,
-                       ConsentConfig):
+                       ConsentConfig,
+                       ServerNoticesConfig,
+                       ):
     pass
 
 
diff --git a/synapse/config/server_notices_config.py b/synapse/config/server_notices_config.py
new file mode 100644
index 0000000000..51ddcac112
--- /dev/null
+++ b/synapse/config/server_notices_config.py
@@ -0,0 +1,85 @@
+# -*- coding: utf-8 -*-
+# Copyright 2018 New Vector Ltd
+#
+# 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.
+from ._base import Config
+from synapse.types import UserID
+
+DEFAULT_CONFIG = """\
+# Server Notices room configuration
+#
+# Uncomment this section to enable a room which can be used to send notices
+# from the server to users. It is a special room which cannot be left; notices
+# come from a special "notices" user id.
+#
+# If you uncomment this section, you *must* define the system_mxid_localpart
+# setting, which defines the id of the user which will be used to send the
+# notices.
+#
+# It's also possible to override the room name, or the display name of the
+# "notices" user.
+#
+# server_notices:
+#   system_mxid_localpart: notices
+#   system_mxid_display_name: "Server Notices"
+#   room_name: "Server Notices"
+"""
+
+
+class ServerNoticesConfig(Config):
+    def __init__(self):
+        super(ServerNoticesConfig, self).__init__()
+
+        """The MXID to use for server notices.
+
+        None if server notices are not enabled.
+
+        type: str|None
+        """
+        self.server_notices_mxid = None
+
+        """The display name to use for the server notices user.
+
+        None if server notices are not enabled.
+
+        type: str|None
+        """
+        self.server_notices_mxid_display_name = None
+
+        """The name to use for the server notices room.
+
+        None if server notices are not enabled.
+
+        (TODO: i18n)
+
+        type: str|None
+        """
+        self.server_notices_room_name = None
+
+    def read_config(self, config):
+        c = config.get("server_notices")
+        if c is None:
+            return
+
+        mxid_localpart = c['system_mxid_localpart']
+        self.server_notices_mxid = UserID(
+            mxid_localpart, self.server_name,
+        ).to_string()
+        self.server_notices_mxid_display_name = c.get(
+            'system_mxid_display_name', 'Server Notices',
+        )
+
+        self.server_notices_room_name = c.get('room_name', "Server Notices")
+
+    def default_config(self, **kwargs):
+        return DEFAULT_CONFIG
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index f83c6b3cf8..7e52adda3c 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -34,6 +34,11 @@ logger = logging.getLogger(__name__)
 class RegistrationHandler(BaseHandler):
 
     def __init__(self, hs):
+        """
+
+        Args:
+            hs (synapse.server.HomeServer):
+        """
         super(RegistrationHandler, self).__init__(hs)
 
         self.auth = hs.get_auth()
@@ -49,6 +54,7 @@ class RegistrationHandler(BaseHandler):
         self._generate_user_id_linearizer = Linearizer(
             name="_generate_user_id_linearizer",
         )
+        self._server_notices_mxid = hs.config.server_notices_mxid
 
     @defer.inlineCallbacks
     def check_username(self, localpart, guest_access_token=None,
@@ -338,6 +344,14 @@ class RegistrationHandler(BaseHandler):
             yield identity_handler.bind_threepid(c, user_id)
 
     def check_user_id_not_appservice_exclusive(self, user_id, allowed_appservice=None):
+        # don't allow people to register the server notices mxid
+        if self._server_notices_mxid is not None:
+            if user_id == self._server_notices_mxid:
+                raise SynapseError(
+                    400, "This user ID is reserved.",
+                    errcode=Codes.EXCLUSIVE
+                )
+
         # valid user IDs must not clash with any user ID namespaces claimed by
         # application services.
         services = self.store.get_app_services()
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index e36426de5a..5e9fa95a2d 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -68,7 +68,8 @@ class RoomCreationHandler(BaseHandler):
         self.event_creation_handler = hs.get_event_creation_handler()
 
     @defer.inlineCallbacks
-    def create_room(self, requester, config, ratelimit=True):
+    def create_room(self, requester, config, ratelimit=True,
+                    creator_join_profile=None):
         """ Creates a new room.
 
         Args:
@@ -76,6 +77,14 @@ class RoomCreationHandler(BaseHandler):
                 The user who requested the room creation.
             config (dict) : A dict of configuration options.
             ratelimit (bool): set to False to disable the rate limiter
+
+            creator_join_profile (dict|None):
+                Set to override the displayname and avatar for the creating
+                user in this room. If unset, displayname and avatar will be
+                derived from the user's profile. If set, should contain the
+                values to go in the body of the 'join' event (typically
+                `avatar_url` and/or `displayname`.
+
         Returns:
             Deferred[dict]:
                 a dict containing the keys `room_id` and, if an alias was
@@ -180,7 +189,8 @@ class RoomCreationHandler(BaseHandler):
             initial_state=initial_state,
             creation_content=creation_content,
             room_alias=room_alias,
-            power_level_content_override=config.get("power_level_content_override", {})
+            power_level_content_override=config.get("power_level_content_override", {}),
+            creator_join_profile=creator_join_profile,
         )
 
         if "name" in config:
@@ -260,6 +270,7 @@ class RoomCreationHandler(BaseHandler):
             creation_content,
             room_alias,
             power_level_content_override,
+            creator_join_profile,
     ):
         def create(etype, content, **kwargs):
             e = {
@@ -303,6 +314,7 @@ class RoomCreationHandler(BaseHandler):
             room_id,
             "join",
             ratelimit=False,
+            content=creator_join_profile,
         )
 
         # We treat the power levels override specially as this needs to be one
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 714583f1d5..9f8975e1f2 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -17,11 +17,14 @@
 import abc
 import logging
 
+from six.moves import http_client
+
 from signedjson.key import decode_verify_key_bytes
 from signedjson.sign import verify_signed_json
 from twisted.internet import defer
 from unpaddedbase64 import decode_base64
 
+import synapse.server
 import synapse.types
 from synapse.api.constants import (
     EventTypes, Membership,
@@ -46,6 +49,11 @@ class RoomMemberHandler(object):
     __metaclass__ = abc.ABCMeta
 
     def __init__(self, hs):
+        """
+
+        Args:
+            hs (synapse.server.HomeServer):
+        """
         self.hs = hs
         self.store = hs.get_datastore()
         self.auth = hs.get_auth()
@@ -63,6 +71,7 @@ class RoomMemberHandler(object):
 
         self.clock = hs.get_clock()
         self.spam_checker = hs.get_spam_checker()
+        self._server_notices_mxid = self.config.server_notices_mxid
 
     @abc.abstractmethod
     def _remote_join(self, requester, remote_room_hosts, room_id, user, content):
@@ -289,12 +298,28 @@ class RoomMemberHandler(object):
             is_blocked = yield self.store.is_room_blocked(room_id)
             if is_blocked:
                 raise SynapseError(403, "This room has been blocked on this server")
+        else:
+            if self._is_server_notice_room(room_id):
+                # we don't allow people to reject invites to, or leave, the
+                # server notice room.
+                raise SynapseError(
+                    http_client.FORBIDDEN,
+                    "You cannot leave this room",
+                )
 
-        if effective_membership_state == "invite":
+        if effective_membership_state == Membership.INVITE:
             block_invite = False
-            is_requester_admin = yield self.auth.is_server_admin(
-                requester.user,
-            )
+
+            if (self._server_notices_mxid is not None and
+                    requester.user.to_string() == self._server_notices_mxid):
+                # allow the server notices mxid to send invites
+                is_requester_admin = True
+
+            else:
+                is_requester_admin = yield self.auth.is_server_admin(
+                    requester.user,
+                )
+
             if not is_requester_admin:
                 if self.config.block_non_admin_invites:
                     logger.info(
@@ -844,6 +869,13 @@ class RoomMemberHandler(object):
 
         defer.returnValue(False)
 
+    @defer.inlineCallbacks
+    def _is_server_notice_room(self, room_id):
+        if self._server_notices_mxid is None:
+            defer.returnValue(False)
+        user_ids = yield self.store.get_users_in_room(room_id)
+        defer.returnValue(self._server_notices_mxid in user_ids)
+
 
 class RoomMemberMasterHandler(RoomMemberHandler):
     def __init__(self, hs):
diff --git a/synapse/server.py b/synapse/server.py
index 9e6f3584b2..85f54cd047 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -72,6 +72,7 @@ from synapse.rest.media.v1.media_repository import (
     MediaRepository,
     MediaRepositoryResource,
 )
+from synapse.server_notices.server_notices_manager import ServerNoticesManager
 from synapse.state import StateHandler, StateResolutionHandler
 from synapse.storage import DataStore
 from synapse.streams.events import EventSources
@@ -156,6 +157,7 @@ class HomeServer(object):
         'spam_checker',
         'room_member_handler',
         'federation_registry',
+        'server_notices_manager',
     ]
 
     def __init__(self, hostname, **kwargs):
@@ -398,6 +400,9 @@ class HomeServer(object):
     def build_federation_registry(self):
         return FederationHandlerRegistry()
 
+    def build_server_notices_manager(self):
+        return ServerNoticesManager(self)
+
     def remove_pusher(self, app_id, push_key, user_id):
         return self.get_pusherpool().remove_pusher(app_id, push_key, user_id)
 
diff --git a/synapse/server.pyi b/synapse/server.pyi
index aeda093f27..6fbe15168d 100644
--- a/synapse/server.pyi
+++ b/synapse/server.pyi
@@ -1,4 +1,5 @@
 import synapse.api.auth
+import synapse.config.homeserver
 import synapse.federation.transaction_queue
 import synapse.federation.transport.client
 import synapse.handlers
@@ -8,11 +9,16 @@ import synapse.handlers.device
 import synapse.handlers.e2e_keys
 import synapse.handlers.set_password
 import synapse.rest.media.v1.media_repository
+import synapse.server_notices.server_notices_manager
 import synapse.state
 import synapse.storage
 
 
 class HomeServer(object):
+    @property
+    def config(self) -> synapse.config.homeserver.HomeServerConfig:
+        pass
+
     def get_auth(self) -> synapse.api.auth.Auth:
         pass
 
@@ -43,6 +49,9 @@ class HomeServer(object):
     def get_room_creation_handler(self) -> synapse.handlers.room.RoomCreationHandler:
         pass
 
+    def get_event_creation_handler(self) -> synapse.handlers.message.EventCreationHandler:
+        pass
+
     def get_set_password_handler(self) -> synapse.handlers.set_password.SetPasswordHandler:
         pass
 
@@ -57,3 +66,6 @@ class HomeServer(object):
 
     def get_media_repository(self) -> synapse.rest.media.v1.media_repository.MediaRepository:
         pass
+
+    def get_server_notices_manager(self) -> synapse.server_notices.server_notices_manager.ServerNoticesManager:
+        pass
diff --git a/synapse/server_notices/__init__.py b/synapse/server_notices/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/synapse/server_notices/__init__.py
diff --git a/synapse/server_notices/server_notices_manager.py b/synapse/server_notices/server_notices_manager.py
new file mode 100644
index 0000000000..0d48aeb95e
--- /dev/null
+++ b/synapse/server_notices/server_notices_manager.py
@@ -0,0 +1,110 @@
+# -*- coding: utf-8 -*-
+# Copyright 2018 New Vector Ltd
+#
+# 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
+
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, Membership, RoomCreationPreset
+from synapse.types import create_requester
+from synapse.util.caches.descriptors import cachedInlineCallbacks
+
+logger = logging.getLogger(__name__)
+
+
+class ServerNoticesManager(object):
+    def __init__(self, hs):
+        """
+
+        Args:
+            hs (synapse.server.HomeServer):
+        """
+
+        self._store = hs.get_datastore()
+        self._config = hs.config
+        self._room_creation_handler = hs.get_room_creation_handler()
+        self._event_creation_handler = hs.get_event_creation_handler()
+
+    def is_enabled(self):
+        return self._config.server_notices_mxid is not None
+
+    @defer.inlineCallbacks
+    def send_notice(self, user_id, event_content):
+        room_id = yield self.get_notice_room_for_user(user_id)
+
+        system_mxid = self._config.server_notices_mxid
+        requester = create_requester(system_mxid)
+
+        logger.info("Sending server notice to %s", user_id)
+
+        yield self._event_creation_handler.create_and_send_nonmember_event(
+            requester, {
+                "type": EventTypes.Message,
+                "room_id": room_id,
+                "sender": system_mxid,
+                "content": event_content,
+            },
+            ratelimit=False,
+        )
+
+    @cachedInlineCallbacks()
+    def get_notice_room_for_user(self, user_id):
+        """Get the room for notices for a given user
+
+        If we have not yet created a notice room for this user, create it
+
+        Args:
+            user_id (str): complete user id for the user we want a room for
+
+        Returns:
+            str: room id of notice room.
+        """
+        if not self.is_enabled():
+            raise Exception("Server notices not enabled")
+
+        rooms = yield self._store.get_rooms_for_user_where_membership_is(
+            user_id, [Membership.INVITE, Membership.JOIN],
+        )
+        system_mxid = self._config.server_notices_mxid
+        for room in rooms:
+            user_ids = yield self._store.get_users_in_room(room.room_id)
+            if system_mxid in user_ids:
+                # we found a room which our user shares with the system notice
+                # user
+                logger.info("Using room %s", room.room_id)
+                defer.returnValue(room.room_id)
+
+        # apparently no existing notice room: create a new one
+        logger.info("Creating server notices room for %s", user_id)
+
+        requester = create_requester(system_mxid)
+        info = yield self._room_creation_handler.create_room(
+            requester,
+            config={
+                "preset": RoomCreationPreset.PRIVATE_CHAT,
+                "name": self._config.server_notices_room_name,
+                "power_level_content_override": {
+                    "users_default": -10,
+                },
+                "invite": (user_id,)
+            },
+            ratelimit=False,
+            creator_join_profile={
+                "displayname": self._config.server_notices_mxid_display_name,
+            },
+        )
+        room_id = info['room_id']
+
+        logger.info("Created server notices room %s for %s", room_id, user_id)
+        defer.returnValue(room_id)