dendrite/roomserver/auth/auth.go
Till 3c1474f68f
Fix /get_missing_events for rooms with joined/invited history_visibility (#2787)
Sytest was using a wrong `history_visibility` for `invited`
(https://github.com/matrix-org/sytest/pull/1303), so `invited` was
passing for the wrong reason (-> defaulted to `shared`, as `invite`
wasn't understood).
This change now handles missing events like Synapse, if a server isn't
allowed to see the event, it gets a redacted version of it, making the
`get_missing_events` tests pass.
2022-10-11 16:04:02 +02:00

94 lines
3.1 KiB
Go

// 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 auth
import (
"github.com/matrix-org/gomatrixserverlib"
)
// TODO: This logic should live in gomatrixserverlib
// IsServerAllowed returns true if the server is allowed to see events in the room
// at this particular state. This function implements https://matrix.org/docs/spec/client_server/r0.6.0#id87
func IsServerAllowed(
serverName gomatrixserverlib.ServerName,
serverCurrentlyInRoom bool,
authEvents []*gomatrixserverlib.Event,
) bool {
historyVisibility := HistoryVisibilityForRoom(authEvents)
// 1. If the history_visibility was set to world_readable, allow.
if historyVisibility == gomatrixserverlib.HistoryVisibilityWorldReadable {
return true
}
// 2. If the user's membership was join, allow.
joinedUserExists := IsAnyUserOnServerWithMembership(serverName, authEvents, gomatrixserverlib.Join)
if joinedUserExists {
return true
}
// 3. If history_visibility was set to shared, and the user joined the room at any point after the event was sent, allow.
if historyVisibility == gomatrixserverlib.HistoryVisibilityShared && serverCurrentlyInRoom {
return true
}
// 4. If the user's membership was invite, and the history_visibility was set to invited, allow.
invitedUserExists := IsAnyUserOnServerWithMembership(serverName, authEvents, gomatrixserverlib.Invite)
if invitedUserExists && historyVisibility == gomatrixserverlib.HistoryVisibilityInvited {
return true
}
// 5. Otherwise, deny.
return false
}
func HistoryVisibilityForRoom(authEvents []*gomatrixserverlib.Event) gomatrixserverlib.HistoryVisibility {
// https://matrix.org/docs/spec/client_server/r0.6.0#id87
// By default if no history_visibility is set, or if the value is not understood, the visibility is assumed to be shared.
visibility := gomatrixserverlib.HistoryVisibilityShared
for _, ev := range authEvents {
if ev.Type() != gomatrixserverlib.MRoomHistoryVisibility {
continue
}
if vis, err := ev.HistoryVisibility(); err == nil {
visibility = vis
}
}
return visibility
}
func IsAnyUserOnServerWithMembership(serverName gomatrixserverlib.ServerName, authEvents []*gomatrixserverlib.Event, wantMembership string) bool {
for _, ev := range authEvents {
if ev.Type() != gomatrixserverlib.MRoomMember {
continue
}
membership, err := ev.Membership()
if err != nil || membership != wantMembership {
continue
}
stateKey := ev.StateKey()
if stateKey == nil {
continue
}
_, domain, err := gomatrixserverlib.SplitID('@', *stateKey)
if err != nil {
continue
}
if domain == serverName {
return true
}
}
return false
}