use go module for dependencies (#594)

roomserver/input/events.go

@@ -0,0 +1,235 @@
+// 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 (
+	"context"
+	"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(
+		ctx context.Context,
+		event gomatrixserverlib.Event,
+		txnAndDeviceID *api.TransactionID,
+		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(
+		ctx context.Context, eventIDs []string,
+	) ([]types.StateEntry, error)
+	// Set the state at an event.
+	SetState(
+		ctx context.Context,
+		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(
+		ctx context.Context, roomNID types.RoomNID,
+	) (updater types.RoomRecentEventsUpdater, err error)
+	// Look up the string event IDs for a list of numeric event IDs
+	EventIDs(
+		ctx context.Context, eventNIDs []types.EventNID,
+	) (map[types.EventNID]string, error)
+	// Build a membership updater for the target user in a room.
+	MembershipUpdater(
+		ctx context.Context, roomID, targerUserID string,
+	) (types.MembershipUpdater, error)
+	// Look up event ID by transaction's info.
+	// This is used to determine if the room event is processed/processing already.
+	// Returns an empty string if no such event exists.
+	GetTransactionEventID(
+		ctx context.Context, transactionID string,
+		deviceID string, userID string,
+	) (string, 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
+}
+
+// processRoomEvent can only be called once at a time
+//
+// TODO(#375): This should be rewritten to allow concurrent calls. The
+// difficulty is in ensuring that we correctly annotate events with the correct
+// state deltas when sending to kafka streams
+func processRoomEvent(
+	ctx context.Context,
+	db RoomEventDatabase,
+	ow OutputRoomEventWriter,
+	input api.InputRoomEvent,
+) (eventID string, err 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(ctx, db, event, input.AuthEventIDs)
+	if err != nil {
+		return
+	}
+
+	if input.TransactionID != nil {
+		tdID := input.TransactionID
+		eventID, err = db.GetTransactionEventID(
+			ctx, tdID.TransactionID, tdID.DeviceID, input.Event.Sender(),
+		)
+		// On error OR event with the transaction already processed/processesing
+		if err != nil || eventID != "" {
+			return
+		}
+	}
+
+	// Store the event
+	roomNID, stateAtEvent, err := db.StoreEvent(ctx, event, input.TransactionID, authEventNIDs)
+	if err != nil {
+		return
+	}
+
+	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 event.EventID(), nil
+	}
+
+	if stateAtEvent.BeforeStateSnapshotNID == 0 {
+		// We haven't calculated a state for this event yet.
+		// Lets calculate one.
+		err = calculateAndSetState(ctx, db, input, roomNID, &stateAtEvent, event)
+		if err != nil {
+			return
+		}
+	}
+
+	if input.Kind == api.KindBackfill {
+		// Backfill is not implemented.
+		panic("Not implemented")
+	}
+
+	// Update the extremities of the event graph for the room
+	return event.EventID(), updateLatestEvents(
+		ctx, db, ow, roomNID, stateAtEvent, event, input.SendAsServer, input.TransactionID,
+	)
+}
+
+func calculateAndSetState(
+	ctx context.Context,
+	db RoomEventDatabase,
+	input api.InputRoomEvent,
+	roomNID types.RoomNID,
+	stateAtEvent *types.StateAtEvent,
+	event gomatrixserverlib.Event,
+) error {
+	var err error
+	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(ctx, input.StateEventIDs); err != nil {
+			return err
+		}
+
+		if stateAtEvent.BeforeStateSnapshotNID, err = db.AddState(ctx, roomNID, nil, entries); err != nil {
+			return err
+		}
+	} 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(ctx, db, event, roomNID); err != nil {
+			return err
+		}
+	}
+	return db.SetState(ctx, stateAtEvent.EventNID, stateAtEvent.BeforeStateSnapshotNID)
+}
+
+func processInviteEvent(
+	ctx context.Context,
+	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(ctx, 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
+}