dendrite/src/github.com/matrix-org/dendrite/roomserver/input/events.go

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// Copyright 2017 Vector Creations 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.
package input
import (
"fmt"
"github.com/matrix-org/dendrite/common"
"github.com/matrix-org/dendrite/roomserver/api"
"github.com/matrix-org/dendrite/roomserver/state"
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/gomatrixserverlib"
)
// A RoomEventDatabase has the storage APIs needed to store a room event.
type RoomEventDatabase interface {
state.RoomStateDatabase
// Stores a matrix room event in the database
StoreEvent(event gomatrixserverlib.Event, authEventNIDs []types.EventNID) (types.RoomNID, types.StateAtEvent, error)
// Look up the state entries for a list of string event IDs
// Returns an error if the there is an error talking to the database
// Returns a types.MissingEventError if the event IDs aren't in the database.
StateEntriesForEventIDs(eventIDs []string) ([]types.StateEntry, error)
// Set the state at an event.
SetState(eventNID types.EventNID, stateNID types.StateSnapshotNID) error
// Look up the latest events in a room in preparation for an update.
// The RoomRecentEventsUpdater must have Commit or Rollback called on it if this doesn't return an error.
// Returns the latest events in the room and the last eventID sent to the log along with an updater.
// If this returns an error then no further action is required.
GetLatestEventsForUpdate(roomNID types.RoomNID) (updater types.RoomRecentEventsUpdater, err error)
// Look up the string event IDs for a list of numeric event IDs
EventIDs(eventNIDs []types.EventNID) (map[types.EventNID]string, error)
// Build a membership updater for the target user in a room.
MembershipUpdater(roomID, targerUserID string) (types.MembershipUpdater, error)
}
// OutputRoomEventWriter has the APIs needed to write an event to the output logs.
type OutputRoomEventWriter interface {
// Write a list of events for a room
WriteOutputEvents(roomID string, updates []api.OutputEvent) error
}
func processRoomEvent(db RoomEventDatabase, ow OutputRoomEventWriter, input api.InputRoomEvent) error {
// Parse and validate the event JSON
event := input.Event
// Check that the event passes authentication checks and work out the numeric IDs for the auth events.
authEventNIDs, err := checkAuthEvents(db, event, input.AuthEventIDs)
if err != nil {
return err
}
// Store the event
roomNID, stateAtEvent, err := db.StoreEvent(event, authEventNIDs)
if err != nil {
return err
}
if input.Kind == api.KindOutlier {
// For outliers we can stop after we've stored the event itself as it
// doesn't have any associated state to store and we don't need to
// notify anyone about it.
return nil
}
if stateAtEvent.BeforeStateSnapshotNID == 0 {
// We haven't calculated a state for this event yet.
// Lets calculate one.
if input.HasState {
// We've been told what the state at the event is so we don't need to calculate it.
// Check that those state events are in the database and store the state.
var entries []types.StateEntry
if entries, err = db.StateEntriesForEventIDs(input.StateEventIDs); err != nil {
return err
}
if stateAtEvent.BeforeStateSnapshotNID, err = db.AddState(roomNID, nil, entries); err != nil {
return nil
}
} else {
// We haven't been told what the state at the event is so we need to calculate it from the prev_events
if stateAtEvent.BeforeStateSnapshotNID, err = state.CalculateAndStoreStateBeforeEvent(db, event, roomNID); err != nil {
return err
}
}
db.SetState(stateAtEvent.EventNID, stateAtEvent.BeforeStateSnapshotNID)
}
if input.Kind == api.KindBackfill {
// Backfill is not implemented.
panic("Not implemented")
}
// Update the extremities of the event graph for the room
if err := updateLatestEvents(db, ow, roomNID, stateAtEvent, event, input.SendAsServer); err != nil {
return err
}
return nil
}
func processInviteEvent(db RoomEventDatabase, ow OutputRoomEventWriter, input api.InputInviteEvent) (err error) {
if input.Event.StateKey() == nil {
return fmt.Errorf("invite must be a state event")
}
roomID := input.Event.RoomID()
targetUserID := *input.Event.StateKey()
updater, err := db.MembershipUpdater(roomID, targetUserID)
if err != nil {
return err
}
succeeded := false
defer common.EndTransaction(updater, &succeeded)
if updater.IsJoin() {
// If the user is joined to the room then that takes precedence over this
// invite event. It makes little sense to move a user that is already
// joined to the room into the invite state.
// This could plausibly happen if an invite request raced with a join
// request for a user. For example if a user was invited to a public
// room and they joined the room at the same time as the invite was sent.
// The other way this could plausibly happen is if an invite raced with
// a kick. For example if a user was kicked from a room in error and in
// response someone else in the room re-invited them then it is possible
// for the invite request to race with the leave event so that the
// target receives invite before it learns that it has been kicked.
// There are a few ways this could be plausibly handled in the roomserver.
// 1) Store the invite, but mark it as retired. That will result in the
// permanent rejection of that invite event. So even if the target
// user leaves the room and the invite is retransmitted it will be
// ignored. However a new invite with a new event ID would still be
// accepted.
// 2) Silently discard the invite event. This means that if the event
// was retransmitted at a later date after the target user had left
// the room we would accept the invite. However since we hadn't told
// the sending server that the invite had been discarded it would
// have no reason to attempt to retry.
// 3) Signal the sending server that the user is already joined to the
// room.
// For now we will implement option 2. Since in the abesence of a retry
// mechanism it will be equivalent to option 1, and we don't have a
// signalling mechanism to implement option 3.
return nil
}
outputUpdates, err := updateToInviteMembership(updater, &input.Event, nil)
if err != nil {
return err
}
if err = ow.WriteOutputEvents(roomID, outputUpdates); err != nil {
return err
}
succeeded = true
return nil
}