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// Copyright 2022 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.
package internal
import (
"context"
"math"
"time"
"github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/gomatrixserverlib/spec"
"github.com/prometheus/client_golang/prometheus"
"github.com/sirupsen/logrus"
"github.com/tidwall/gjson"
"github.com/matrix-org/dendrite/roomserver/api"
"github.com/matrix-org/dendrite/syncapi/storage"
)
func init() {
prometheus.MustRegister(calculateHistoryVisibilityDuration)
}
// calculateHistoryVisibilityDuration stores the time it takes to
// calculate the history visibility.
var calculateHistoryVisibilityDuration = prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Namespace: "dendrite",
Subsystem: "syncapi",
Name: "calculateHistoryVisibility_duration_millis",
Help: "How long it takes to calculate the history visibility",
Buckets: []float64{ // milliseconds
5, 10, 25, 50, 75, 100, 250, 500,
1000, 2000, 3000, 4000, 5000, 6000,
7000, 8000, 9000, 10000, 15000, 20000,
},
},
[]string{"api"},
)
var historyVisibilityPriority = map[gomatrixserverlib.HistoryVisibility]uint8{
spec.WorldReadable: 0,
gomatrixserverlib.HistoryVisibilityShared: 1,
gomatrixserverlib.HistoryVisibilityInvited: 2,
gomatrixserverlib.HistoryVisibilityJoined: 3,
}
// eventVisibility contains the history visibility and membership state at a given event
type eventVisibility struct {
visibility gomatrixserverlib.HistoryVisibility
membershipAtEvent string
membershipCurrent string
}
// allowed checks the eventVisibility if the user is allowed to see the event.
// Rules as defined by https://spec.matrix.org/v1.3/client-server-api/#server-behaviour-5
func (ev eventVisibility) allowed() (allowed bool) {
switch ev.visibility {
case gomatrixserverlib.HistoryVisibilityWorldReadable:
// If the history_visibility was set to world_readable, allow.
return true
case gomatrixserverlib.HistoryVisibilityJoined:
// If the user’s membership was join, allow.
if ev.membershipAtEvent == spec.Join {
return true
}
return false
case gomatrixserverlib.HistoryVisibilityShared:
// If the user’s membership was join, allow.
// If history_visibility was set to shared, and the user joined the room at any point after the event was sent, allow.
if ev.membershipAtEvent == spec.Join || ev.membershipCurrent == spec.Join {
return true
}
return false
case gomatrixserverlib.HistoryVisibilityInvited:
// If the user’s membership was join, allow.
if ev.membershipAtEvent == spec.Join {
return true
}
if ev.membershipAtEvent == spec.Invite {
return true
}
return false
default:
return false
}
}
// ApplyHistoryVisibilityFilter applies the room history visibility filter on gomatrixserverlib.HeaderedEvents.
// Returns the filtered events and an error, if any.
func ApplyHistoryVisibilityFilter(
ctx context.Context,
syncDB storage.DatabaseTransaction,
rsAPI api.SyncRoomserverAPI,
events []*gomatrixserverlib.HeaderedEvent,
alwaysIncludeEventIDs map[string]struct{},
userID, endpoint string,
) ([]*gomatrixserverlib.HeaderedEvent, error) {
if len(events) == 0 {
return events, nil
}
start := time.Now()
// try to get the current membership of the user
membershipCurrent, _, err := syncDB.SelectMembershipForUser(ctx, events[0].RoomID(), userID, math.MaxInt64)
if err != nil {
return nil, err
}
// Get the mapping from eventID -> eventVisibility
eventsFiltered := make([]*gomatrixserverlib.HeaderedEvent, 0, len(events))
visibilities := visibilityForEvents(ctx, rsAPI, events, userID, events[0].RoomID())
for _, ev := range events {
evVis := visibilities[ev.EventID()]
evVis.membershipCurrent = membershipCurrent
// Always include specific state events for /sync responses
if alwaysIncludeEventIDs != nil {
if _, ok := alwaysIncludeEventIDs[ev.EventID()]; ok {
eventsFiltered = append(eventsFiltered, ev)
continue
}
}
// NOTSPEC: Always allow user to see their own membership events (spec contains more "rules")
if ev.Type() == spec.MRoomMember && ev.StateKeyEquals(userID) {
eventsFiltered = append(eventsFiltered, ev)
continue
}
// Always allow history evVis events on boundaries. This is done
// by setting the effective evVis to the least restrictive
// of the old vs new.
// https://spec.matrix.org/v1.3/client-server-api/#server-behaviour-5
if hisVis, err := ev.HistoryVisibility(); err == nil {
prevHisVis := gjson.GetBytes(ev.Unsigned(), "prev_content.history_visibility").String()
oldPrio, ok := historyVisibilityPriority[gomatrixserverlib.HistoryVisibility(prevHisVis)]
// if we can't get the previous history visibility, default to shared.
if !ok {
oldPrio = historyVisibilityPriority[gomatrixserverlib.HistoryVisibilityShared]
}
// no OK check, since this should have been validated when setting the value
newPrio := historyVisibilityPriority[hisVis]
if oldPrio < newPrio {
evVis.visibility = gomatrixserverlib.HistoryVisibility(prevHisVis)
}
}
// do the actual check
allowed := evVis.allowed()
if allowed {
eventsFiltered = append(eventsFiltered, ev)
}
}
calculateHistoryVisibilityDuration.With(prometheus.Labels{"api": endpoint}).Observe(float64(time.Since(start).Milliseconds()))
return eventsFiltered, nil
}
// visibilityForEvents returns a map from eventID to eventVisibility containing the visibility and the membership
// of `userID` at the given event.
// Returns an error if the roomserver can't calculate the memberships.
func visibilityForEvents(
ctx context.Context,
rsAPI api.SyncRoomserverAPI,
events []*gomatrixserverlib.HeaderedEvent,
userID, roomID string,
) map[string]eventVisibility {
eventIDs := make([]string, len(events))
for i := range events {
eventIDs[i] = events[i].EventID()
}
result := make(map[string]eventVisibility, len(eventIDs))
// get the membership events for all eventIDs
membershipResp := &api.QueryMembershipAtEventResponse{}
err := rsAPI.QueryMembershipAtEvent(ctx, &api.QueryMembershipAtEventRequest{
RoomID: roomID,
EventIDs: eventIDs,
UserID: userID,
}, membershipResp)
if err != nil {
logrus.WithError(err).Error("visibilityForEvents: failed to fetch membership at event, defaulting to 'leave'")
}
// Create a map from eventID -> eventVisibility
for _, event := range events {
eventID := event.EventID()
vis := eventVisibility{
membershipAtEvent: spec.Leave, // default to leave, to not expose events by accident
visibility: event.Visibility,
}
ev, ok := membershipResp.Membership[eventID]
if !ok || ev == nil {
result[eventID] = vis
continue
}
membership, err := ev.Membership()
if err != nil {
result[eventID] = vis
continue
}
vis.membershipAtEvent = membership
result[eventID] = vis
}
return result
}
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