Merge pull request #777 from matrix-org/markjh/move_filter_for_client

move filter_events_for_client out of base handler

1 files changed, 210 insertions, 0 deletions

diff --git a/synapse/visibility.py b/synapse/visibility.py
new file mode 100644
index 0000000000..948ad51772
--- /dev/null
+++ b/synapse/visibility.py
@@ -0,0 +1,210 @@
+# -*- coding: utf-8 -*-
+# Copyright 2014 - 2016 OpenMarket 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 twisted.internet import defer
+
+from synapse.api.constants import Membership, EventTypes
+
+from synapse.util.logcontext import preserve_fn
+
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
+VISIBILITY_PRIORITY = (
+    "world_readable",
+    "shared",
+    "invited",
+    "joined",
+)
+
+
+MEMBERSHIP_PRIORITY = (
+    Membership.JOIN,
+    Membership.INVITE,
+    Membership.KNOCK,
+    Membership.LEAVE,
+    Membership.BAN,
+)
+
+
+@defer.inlineCallbacks
+def filter_events_for_clients(store, user_tuples, events, event_id_to_state):
+    """ Returns dict of user_id -> list of events that user is allowed to
+    see.
+
+    Args:
+        user_tuples (str, bool): (user id, is_peeking) for each user to be
+            checked. is_peeking should be true if:
+            * the user is not currently a member of the room, and:
+            * the user has not been a member of the room since the
+            given events
+        events ([synapse.events.EventBase]): list of events to filter
+    """
+    forgotten = yield defer.gatherResults([
+        preserve_fn(store.who_forgot_in_room)(
+            room_id,
+        )
+        for room_id in frozenset(e.room_id for e in events)
+    ], consumeErrors=True)
+
+    # Set of membership event_ids that have been forgotten
+    event_id_forgotten = frozenset(
+        row["event_id"] for rows in forgotten for row in rows
+    )
+
+    ignore_dict_content = yield store.get_global_account_data_by_type_for_users(
+        "m.ignored_user_list", user_ids=[user_id for user_id, _ in user_tuples]
+    )
+
+    # FIXME: This will explode if people upload something incorrect.
+    ignore_dict = {
+        user_id: frozenset(
+            content.get("ignored_users", {}).keys() if content else []
+        )
+        for user_id, content in ignore_dict_content.items()
+    }
+
+    def allowed(event, user_id, is_peeking, ignore_list):
+        """
+        Args:
+            event (synapse.events.EventBase): event to check
+            user_id (str)
+            is_peeking (bool)
+            ignore_list (list): list of users to ignore
+        """
+        if not event.is_state() and event.sender in ignore_list:
+            return False
+
+        state = event_id_to_state[event.event_id]
+
+        # get the room_visibility at the time of the event.
+        visibility_event = state.get((EventTypes.RoomHistoryVisibility, ""), None)
+        if visibility_event:
+            visibility = visibility_event.content.get("history_visibility", "shared")
+        else:
+            visibility = "shared"
+
+        if visibility not in VISIBILITY_PRIORITY:
+            visibility = "shared"
+
+        # if it was world_readable, it's easy: everyone can read it
+        if visibility == "world_readable":
+            return True
+
+        # Always allow history visibility events on boundaries. This is done
+        # by setting the effective visibility to the least restrictive
+        # of the old vs new.
+        if event.type == EventTypes.RoomHistoryVisibility:
+            prev_content = event.unsigned.get("prev_content", {})
+            prev_visibility = prev_content.get("history_visibility", None)
+
+            if prev_visibility not in VISIBILITY_PRIORITY:
+                prev_visibility = "shared"
+
+            new_priority = VISIBILITY_PRIORITY.index(visibility)
+            old_priority = VISIBILITY_PRIORITY.index(prev_visibility)
+            if old_priority < new_priority:
+                visibility = prev_visibility
+
+        # likewise, if the event is the user's own membership event, use
+        # the 'most joined' membership
+        membership = None
+        if event.type == EventTypes.Member and event.state_key == user_id:
+            membership = event.content.get("membership", None)
+            if membership not in MEMBERSHIP_PRIORITY:
+                membership = "leave"
+
+            prev_content = event.unsigned.get("prev_content", {})
+            prev_membership = prev_content.get("membership", None)
+            if prev_membership not in MEMBERSHIP_PRIORITY:
+                prev_membership = "leave"
+
+            new_priority = MEMBERSHIP_PRIORITY.index(membership)
+            old_priority = MEMBERSHIP_PRIORITY.index(prev_membership)
+            if old_priority < new_priority:
+                membership = prev_membership
+
+        # otherwise, get the user's membership at the time of the event.
+        if membership is None:
+            membership_event = state.get((EventTypes.Member, user_id), None)
+            if membership_event:
+                if membership_event.event_id not in event_id_forgotten:
+                    membership = membership_event.membership
+
+        # if the user was a member of the room at the time of the event,
+        # they can see it.
+        if membership == Membership.JOIN:
+            return True
+
+        if visibility == "joined":
+            # we weren't a member at the time of the event, so we can't
+            # see this event.
+            return False
+
+        elif visibility == "invited":
+            # user can also see the event if they were *invited* at the time
+            # of the event.
+            return membership == Membership.INVITE
+
+        else:
+            # visibility is shared: user can also see the event if they have
+            # become a member since the event
+            #
+            # XXX: if the user has subsequently joined and then left again,
+            # ideally we would share history up to the point they left. But
+            # we don't know when they left.
+            return not is_peeking
+
+    defer.returnValue({
+        user_id: [
+            event
+            for event in events
+            if allowed(event, user_id, is_peeking, ignore_dict.get(user_id, []))
+        ]
+        for user_id, is_peeking in user_tuples
+    })
+
+
+@defer.inlineCallbacks
+def filter_events_for_client(store, user_id, events, is_peeking=False):
+    """
+    Check which events a user is allowed to see
+
+    Args:
+        user_id(str): user id to be checked
+        events([synapse.events.EventBase]): list of events to be checked
+        is_peeking(bool): should be True if:
+          * the user is not currently a member of the room, and:
+          * the user has not been a member of the room since the given
+            events
+
+    Returns:
+        [synapse.events.EventBase]
+    """
+    types = (
+        (EventTypes.RoomHistoryVisibility, ""),
+        (EventTypes.Member, user_id),
+    )
+    event_id_to_state = yield store.get_state_for_events(
+        frozenset(e.event_id for e in events),
+        types=types
+    )
+    res = yield filter_events_for_clients(
+        store, [(user_id, is_peeking)], events, event_id_to_state
+    )
+    defer.returnValue(res.get(user_id, []))