Room version upgrade support

changelog.d/4091.feature

@@ -0,0 +1 @@
+Support for replacing rooms with new ones

synapse/api/constants.py

@@ -61,6 +61,7 @@ class LoginType(object):
 class EventTypes(object):
     Member = "m.room.member"
     Create = "m.room.create"
+    Tombstone = "m.room.tombstone"
     JoinRules = "m.room.join_rules"
     PowerLevels = "m.room.power_levels"
     Aliases = "m.room.aliases"

synapse/handlers/register.py

@@ -50,7 +50,6 @@ def __init__(self, hs):
         self._auth_handler = hs.get_auth_handler()
         self.profile_handler = hs.get_profile_handler()
         self.user_directory_handler = hs.get_user_directory_handler()
-        self.room_creation_handler = self.hs.get_room_creation_handler()
         self.captcha_client = CaptchaServerHttpClient(hs)
 
         self._next_generated_user_id = None
@@ -241,7 +240,10 @@ def register(
                     else:
                         # create room expects the localpart of the room alias
                         room_alias_localpart = room_alias.localpart
-                        yield self.room_creation_handler.create_room(
+
+                        # getting the RoomCreationHandler during init gives a dependency
+                        # loop
+                        yield self.hs.get_room_creation_handler().create_room(
                             fake_requester,
                             config={
                                 "preset": "public_chat",

synapse/handlers/room.py

@@ -32,10 +32,11 @@
     JoinRules,
     RoomCreationPreset,
 )
-from synapse.api.errors import AuthError, Codes, StoreError, SynapseError
+from synapse.api.errors import AuthError, Codes, NotFoundError, StoreError, SynapseError
 from synapse.storage.state import StateFilter
 from synapse.types import RoomAlias, RoomID, RoomStreamToken, StreamToken, UserID
 from synapse.util import stringutils
+from synapse.util.async_helpers import Linearizer
 from synapse.visibility import filter_events_for_client
 
 from ._base import BaseHandler
@@ -73,6 +74,190 @@ def __init__(self, hs):
 
         self.spam_checker = hs.get_spam_checker()
         self.event_creation_handler = hs.get_event_creation_handler()
+        self.room_member_handler = hs.get_room_member_handler()
+
+        # linearizer to stop two upgrades happening at once
+        self._upgrade_linearizer = Linearizer("room_upgrade_linearizer")
+
+    @defer.inlineCallbacks
+    def upgrade_room(self, requester, old_room_id, new_version):
+        """Replace a room with a new room with a different version
+
+        Args:
+            requester (synapse.types.Requester): the user requesting the upgrade
+            old_room_id (unicode): the id of the room to be replaced
+            new_version (unicode): the new room version to use
+
+        Returns:
+            Deferred[unicode]: the new room id
+        """
+        yield self.ratelimit(requester)
+
+        user_id = requester.user.to_string()
+
+        with (yield self._upgrade_linearizer.queue(old_room_id)):
+            # start by allocating a new room id
+            r = yield self.store.get_room(old_room_id)
+            if r is None:
+                raise NotFoundError("Unknown room id %s" % (old_room_id,))
+            new_room_id = yield self._generate_room_id(
+                creator_id=user_id, is_public=r["is_public"],
+            )
+
+            # we create and auth the tombstone event before properly creating the new
+            # room, to check our user has perms in the old room.
+            tombstone_event, tombstone_context = (
+                yield self.event_creation_handler.create_event(
+                    requester, {
+                        "type": EventTypes.Tombstone,
+                        "state_key": "",
+                        "room_id": old_room_id,
+                        "sender": user_id,
+                        "content": {
+                            "body": "This room has been replaced",
+                            "replacement_room": new_room_id,
+                        }
+                    },
+                    token_id=requester.access_token_id,
+                )
+            )
+            yield self.auth.check_from_context(tombstone_event, tombstone_context)
+
+            yield self.clone_exiting_room(
+                requester,
+                old_room_id=old_room_id,
+                new_room_id=new_room_id,
+                new_room_version=new_version,
+                tombstone_event_id=tombstone_event.event_id,
+            )
+
+            # now send the tombstone
+            yield self.event_creation_handler.send_nonmember_event(
+                requester, tombstone_event, tombstone_context,
+            )
+
+            # ... and restrict the PLs in the old room, if possible.
+            old_room_pl_state = yield self.state_handler.get_current_state(
+                old_room_id,
+                event_type=EventTypes.PowerLevels,
+                latest_event_ids=(tombstone_event.event_id, ),
+            )
+
+            if old_room_pl_state is None:
+                logger.warning(
+                    "Not supported: upgrading a room with no PL event. Not setting PLs "
+                    "in old room.",
+                )
+            else:
+                pl_content = dict(old_room_pl_state.content)
+                users_default = int(pl_content.get("users_default", 0))
+                restricted_level = max(users_default + 1, 50)
+
+                updated = False
+                for v in ("invite", "events_default"):
+                    current = int(pl_content.get(v, 0))
+                    if current < restricted_level:
+                        logger.debug(
+                            "Setting level for %s in %s to %i (was %i)",
+                            v, old_room_id, restricted_level, current,
+                        )
+                        pl_content[v] = restricted_level
+                        updated = True
+                    else:
+                        logger.debug(
+                            "Not setting level for %s (already %i)",
+                            v, current,
+                        )
+
+                if updated:
+                    yield self.event_creation_handler.create_and_send_nonmember_event(
+                        requester, {
+                            "type": EventTypes.PowerLevels,
+                            "state_key": '',
+                            "room_id": old_room_id,
+                            "sender": user_id,
+                            "content": pl_content,
+                        }, ratelimit=False,
+                    )
+
+        defer.returnValue(new_room_id)
+
+    @defer.inlineCallbacks
+    def clone_exiting_room(
+            self, requester, old_room_id, new_room_id, new_room_version,
+            tombstone_event_id,
+    ):
+        """Populate a new room based on an old room
+
+        Args:
+            requester (synapse.types.Requester): the user requesting the upgrade
+            old_room_id (unicode): the id of the room to be replaced
+            new_room_id (unicode): the id to give the new room (should already have been
+                created with _gemerate_room_id())
+            new_room_version (unicode): the new room version to use
+            tombstone_event_id (unicode|str): the ID of the tombstone event in the old
+                room.
+        Returns:
+            Deferred[None]
+        """
+        user_id = requester.user.to_string()
+
+        if not self.spam_checker.user_may_create_room(user_id):
+            raise SynapseError(403, "You are not permitted to create rooms")
+
+        # XXX check alias is free
+        # canonical_alias = None
+
+        # XXX create association in directory handler
+
+        creation_content = {
+            "room_version": new_room_version,
+            "predecessor": {
+                "room_id": old_room_id,
+                "event_id": tombstone_event_id,
+            }
+        }
+
+        initial_state = dict()
+
+        types_to_copy = (
+            (EventTypes.PowerLevels, ""),
+            (EventTypes.JoinRules, ""),
+            (EventTypes.Name, ""),
+            (EventTypes.Topic, ""),
+            (EventTypes.RoomHistoryVisibility, ""),
+            (EventTypes.GuestAccess, "")
+        )
+
+        old_room_state_ids = yield self.store.get_filtered_current_state_ids(
+            old_room_id, StateFilter.from_types(types_to_copy),
+        )
+        # map from event_id to BaseEvent
+        old_room_state_events = yield self.store.get_events(old_room_state_ids.values())
+
+        for k in types_to_copy:
+            old_event_id = old_room_state_ids.get(k)
+            if old_event_id:
+                old_event = old_room_state_events.get(old_event_id)
+                if old_event:
+                    initial_state[k] = old_event.content
+
+        yield self._send_events_for_new_room(
+            requester,
+            new_room_id,
+
+            # we expect to override all the presets with initial_state, so this is
+            # somewhat arbitrary.
+            preset_config=RoomCreationPreset.PRIVATE_CHAT,
+
+            invite_list=[],
+            initial_state=initial_state,
+            creation_content=creation_content,
+        )
+
+        # XXX invites/joins
+        # XXX 3pid invites
+        # XXX directory_handler.send_room_alias_update_event
 
     @defer.inlineCallbacks
     def create_room(self, requester, config, ratelimit=True,
@@ -165,28 +350,7 @@ def create_room(self, requester, config, ratelimit=True,
         visibility = config.get("visibility", None)
         is_public = visibility == "public"
 
-        # autogen room IDs and try to create it. We may clash, so just
-        # try a few times till one goes through, giving up eventually.
-        attempts = 0
-        room_id = None
-        while attempts < 5:
-            try:
-                random_string = stringutils.random_string(18)
-                gen_room_id = RoomID(
-                    random_string,
-                    self.hs.hostname,
-                )
-                yield self.store.store_room(
-                    room_id=gen_room_id.to_string(),
-                    room_creator_user_id=user_id,
-                    is_public=is_public
-                )
-                room_id = gen_room_id.to_string()
-                break
-            except StoreError:
-                attempts += 1
-        if not room_id:
-            raise StoreError(500, "Couldn't generate a room ID.")
+        room_id = yield self._generate_room_id(creator_id=user_id, is_public=is_public)
 
         if room_alias:
             directory_handler = self.hs.get_handlers().directory_handler
@@ -216,18 +380,15 @@ def create_room(self, requester, config, ratelimit=True,
         # override any attempt to set room versions via the creation_content
         creation_content["room_version"] = room_version
 
-        room_member_handler = self.hs.get_room_member_handler()
-
         yield self._send_events_for_new_room(
             requester,
             room_id,
-            room_member_handler,
             preset_config=preset_config,
             invite_list=invite_list,
             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,
         )
 
@@ -263,7 +424,7 @@ def create_room(self, requester, config, ratelimit=True,
             if is_direct:
                 content["is_direct"] = is_direct
 
-            yield room_member_handler.update_membership(
+            yield self.room_member_handler.update_membership(
                 requester,
                 UserID.from_string(invitee),
                 room_id,
@@ -301,14 +462,13 @@ def _send_events_for_new_room(
             self,
             creator,  # A Requester object.
             room_id,
-            room_member_handler,
             preset_config,
             invite_list,
             initial_state,
             creation_content,
-            room_alias,
-            power_level_content_override,
-            creator_join_profile,
+            room_alias=None,
+            power_level_content_override=None,
+            creator_join_profile=None,
     ):
         def create(etype, content, **kwargs):
             e = {
@@ -346,7 +506,7 @@ def send(etype, content, **kwargs):
             content=creation_content,
         )
 
-        yield room_member_handler.update_membership(
+        yield self.room_member_handler.update_membership(
             creator,
             creator.user,
             room_id,
@@ -388,7 +548,8 @@ def send(etype, content, **kwargs):
                 for invitee in invite_list:
                     power_level_content["users"][invitee] = 100
 
-            power_level_content.update(power_level_content_override)
+            if power_level_content_override:
+                power_level_content.update(power_level_content_override)
 
             yield send(
                 etype=EventTypes.PowerLevels,
@@ -427,6 +588,30 @@ def send(etype, content, **kwargs):
                 content=content,
             )
 
+    @defer.inlineCallbacks
+    def _generate_room_id(self, creator_id, is_public):
+        # autogen room IDs and try to create it. We may clash, so just
+        # try a few times till one goes through, giving up eventually.
+        attempts = 0
+        while attempts < 5:
+            try:
+                random_string = stringutils.random_string(18)
+                gen_room_id = RoomID(
+                    random_string,
+                    self.hs.hostname,
+                ).to_string()
+                if isinstance(gen_room_id, bytes):
+                    gen_room_id = gen_room_id.decode('utf-8')
+                yield self.store.store_room(
+                    room_id=gen_room_id,
+                    room_creator_user_id=creator_id,
+                    is_public=is_public,
+                )
+                defer.returnValue(gen_room_id)
+            except StoreError:
+                attempts += 1
+        raise StoreError(500, "Couldn't generate a room ID.")
+
 
 class RoomContextHandler(object):
     def __init__(self, hs):

synapse/rest/__init__.py

@@ -47,6 +47,7 @@
     register,
     report_event,
     room_keys,
+    room_upgrade_rest_servlet,
     sendtodevice,
     sync,
     tags,
@@ -116,3 +117,4 @@ def register_servlets(client_resource, hs):
         sendtodevice.register_servlets(hs, client_resource)
         user_directory.register_servlets(hs, client_resource)
         groups.register_servlets(hs, client_resource)
+        room_upgrade_rest_servlet.register_servlets(hs, client_resource)