package shared import ( "context" "database/sql" "encoding/json" "fmt" "github.com/matrix-org/dendrite/internal/caching" "github.com/matrix-org/dendrite/internal/sqlutil" "github.com/matrix-org/dendrite/roomserver/api" "github.com/matrix-org/dendrite/roomserver/storage/tables" "github.com/matrix-org/dendrite/roomserver/types" "github.com/matrix-org/gomatrixserverlib" "github.com/tidwall/gjson" ) // Ideally, when we have both events we should redact the event JSON and forget about the redaction, but we currently // don't because the redaction code is brand new. When we are more certain that redactions don't misbehave or are // vulnerable to attacks from remote servers (e.g a server bypassing event auth rules shouldn't redact our data) // then we should flip this to true. This will mean redactions /actually delete information irretrievably/ which // will be necessary for compliance with the law. Note that downstream components (syncapi) WILL delete information // in their database on receipt of a redaction. Also note that we still modify the event JSON to set the field // unsigned.redacted_because - we just don't clear out the content fields yet. const redactionsArePermanent = true type Database struct { DB *sql.DB Cache caching.RoomServerCaches Writer sqlutil.Writer EventsTable tables.Events EventJSONTable tables.EventJSON EventTypesTable tables.EventTypes EventStateKeysTable tables.EventStateKeys RoomsTable tables.Rooms TransactionsTable tables.Transactions StateSnapshotTable tables.StateSnapshot StateBlockTable tables.StateBlock RoomAliasesTable tables.RoomAliases PrevEventsTable tables.PreviousEvents InvitesTable tables.Invites MembershipTable tables.Membership PublishedTable tables.Published RedactionsTable tables.Redactions } func (d *Database) SupportsConcurrentRoomInputs() bool { return true } func (d *Database) EventTypeNIDs( ctx context.Context, eventTypes []string, ) (map[string]types.EventTypeNID, error) { result := make(map[string]types.EventTypeNID) remaining := []string{} for _, eventType := range eventTypes { if nid, ok := d.Cache.GetRoomServerEventTypeNID(eventType); ok { result[eventType] = nid } else { remaining = append(remaining, eventType) } } if len(remaining) > 0 { nids, err := d.EventTypesTable.BulkSelectEventTypeNID(ctx, remaining) if err != nil { return nil, err } for eventType, nid := range nids { result[eventType] = nid d.Cache.StoreRoomServerEventTypeNID(eventType, nid) } } return result, nil } func (d *Database) EventStateKeys( ctx context.Context, eventStateKeyNIDs []types.EventStateKeyNID, ) (map[types.EventStateKeyNID]string, error) { return d.EventStateKeysTable.BulkSelectEventStateKey(ctx, eventStateKeyNIDs) } func (d *Database) EventStateKeyNIDs( ctx context.Context, eventStateKeys []string, ) (map[string]types.EventStateKeyNID, error) { result := make(map[string]types.EventStateKeyNID) remaining := []string{} for _, eventStateKey := range eventStateKeys { if nid, ok := d.Cache.GetRoomServerStateKeyNID(eventStateKey); ok { result[eventStateKey] = nid } else { remaining = append(remaining, eventStateKey) } } if len(remaining) > 0 { nids, err := d.EventStateKeysTable.BulkSelectEventStateKeyNID(ctx, remaining) if err != nil { return nil, err } for eventStateKey, nid := range nids { result[eventStateKey] = nid d.Cache.StoreRoomServerStateKeyNID(eventStateKey, nid) } } return result, nil } func (d *Database) StateEntriesForEventIDs( ctx context.Context, eventIDs []string, ) ([]types.StateEntry, error) { return d.EventsTable.BulkSelectStateEventByID(ctx, eventIDs) } func (d *Database) StateEntriesForTuples( ctx context.Context, stateBlockNIDs []types.StateBlockNID, stateKeyTuples []types.StateKeyTuple, ) ([]types.StateEntryList, error) { return d.StateBlockTable.BulkSelectFilteredStateBlockEntries( ctx, stateBlockNIDs, stateKeyTuples, ) } func (d *Database) RoomInfo(ctx context.Context, roomID string) (*types.RoomInfo, error) { return d.RoomsTable.SelectRoomInfo(ctx, roomID) } func (d *Database) AddState( ctx context.Context, roomNID types.RoomNID, stateBlockNIDs []types.StateBlockNID, state []types.StateEntry, ) (stateNID types.StateSnapshotNID, err error) { err = d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error { if len(state) > 0 { var stateBlockNID types.StateBlockNID stateBlockNID, err = d.StateBlockTable.BulkInsertStateData(ctx, txn, state) if err != nil { return fmt.Errorf("d.StateBlockTable.BulkInsertStateData: %w", err) } stateBlockNIDs = append(stateBlockNIDs[:len(stateBlockNIDs):len(stateBlockNIDs)], stateBlockNID) } stateNID, err = d.StateSnapshotTable.InsertState(ctx, txn, roomNID, stateBlockNIDs) if err != nil { return fmt.Errorf("d.StateSnapshotTable.InsertState: %w", err) } return nil }) if err != nil { return 0, fmt.Errorf("d.Writer.Do: %w", err) } return } func (d *Database) EventNIDs( ctx context.Context, eventIDs []string, ) (map[string]types.EventNID, error) { return d.EventsTable.BulkSelectEventNID(ctx, eventIDs) } func (d *Database) SetState( ctx context.Context, eventNID types.EventNID, stateNID types.StateSnapshotNID, ) error { return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error { return d.EventsTable.UpdateEventState(ctx, txn, eventNID, stateNID) }) } func (d *Database) StateAtEventIDs( ctx context.Context, eventIDs []string, ) ([]types.StateAtEvent, error) { return d.EventsTable.BulkSelectStateAtEventByID(ctx, eventIDs) } func (d *Database) SnapshotNIDFromEventID( ctx context.Context, eventID string, ) (types.StateSnapshotNID, error) { _, stateNID, err := d.EventsTable.SelectEvent(ctx, nil, eventID) return stateNID, err } func (d *Database) EventIDs( ctx context.Context, eventNIDs []types.EventNID, ) (map[types.EventNID]string, error) { return d.EventsTable.BulkSelectEventID(ctx, eventNIDs) } func (d *Database) EventsFromIDs(ctx context.Context, eventIDs []string) ([]types.Event, error) { nidMap, err := d.EventNIDs(ctx, eventIDs) if err != nil { return nil, err } var nids []types.EventNID for _, nid := range nidMap { nids = append(nids, nid) } return d.Events(ctx, nids) } func (d *Database) LatestEventIDs( ctx context.Context, roomNID types.RoomNID, ) (references []gomatrixserverlib.EventReference, currentStateSnapshotNID types.StateSnapshotNID, depth int64, err error) { var eventNIDs []types.EventNID eventNIDs, currentStateSnapshotNID, err = d.RoomsTable.SelectLatestEventNIDs(ctx, nil, roomNID) if err != nil { return } references, err = d.EventsTable.BulkSelectEventReference(ctx, nil, eventNIDs) if err != nil { return } depth, err = d.EventsTable.SelectMaxEventDepth(ctx, nil, eventNIDs) if err != nil { return } return } func (d *Database) StateBlockNIDs( ctx context.Context, stateNIDs []types.StateSnapshotNID, ) ([]types.StateBlockNIDList, error) { return d.StateSnapshotTable.BulkSelectStateBlockNIDs(ctx, stateNIDs) } func (d *Database) StateEntries( ctx context.Context, stateBlockNIDs []types.StateBlockNID, ) ([]types.StateEntryList, error) { return d.StateBlockTable.BulkSelectStateBlockEntries(ctx, stateBlockNIDs) } func (d *Database) GetRoomVersionForRoom( ctx context.Context, roomID string, ) (gomatrixserverlib.RoomVersion, error) { if roomVersion, ok := d.Cache.GetRoomVersion(roomID); ok { return roomVersion, nil } return d.RoomsTable.SelectRoomVersionForRoomID( ctx, nil, roomID, ) } func (d *Database) GetRoomVersionForRoomNID( ctx context.Context, roomNID types.RoomNID, ) (gomatrixserverlib.RoomVersion, error) { if roomID, ok := d.Cache.GetRoomServerRoomID(roomNID); ok { if roomVersion, ok := d.Cache.GetRoomVersion(roomID); ok { return roomVersion, nil } } return d.RoomsTable.SelectRoomVersionForRoomNID( ctx, roomNID, ) } func (d *Database) SetRoomAlias(ctx context.Context, alias string, roomID string, creatorUserID string) error { return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error { return d.RoomAliasesTable.InsertRoomAlias(ctx, txn, alias, roomID, creatorUserID) }) } func (d *Database) GetRoomIDForAlias(ctx context.Context, alias string) (string, error) { return d.RoomAliasesTable.SelectRoomIDFromAlias(ctx, alias) } func (d *Database) GetAliasesForRoomID(ctx context.Context, roomID string) ([]string, error) { return d.RoomAliasesTable.SelectAliasesFromRoomID(ctx, roomID) } func (d *Database) GetCreatorIDForAlias( ctx context.Context, alias string, ) (string, error) { return d.RoomAliasesTable.SelectCreatorIDFromAlias(ctx, alias) } func (d *Database) RemoveRoomAlias(ctx context.Context, alias string) error { return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error { return d.RoomAliasesTable.DeleteRoomAlias(ctx, txn, alias) }) } func (d *Database) GetMembership( ctx context.Context, roomNID types.RoomNID, requestSenderUserID string, ) (membershipEventNID types.EventNID, stillInRoom bool, err error) { var requestSenderUserNID types.EventStateKeyNID err = d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error { requestSenderUserNID, err = d.assignStateKeyNID(ctx, txn, requestSenderUserID) return err }) if err != nil { return 0, false, fmt.Errorf("d.assignStateKeyNID: %w", err) } senderMembershipEventNID, senderMembership, err := d.MembershipTable.SelectMembershipFromRoomAndTarget( ctx, roomNID, requestSenderUserNID, ) if err == sql.ErrNoRows { // The user has never been a member of that room return 0, false, nil } else if err != nil { return } return senderMembershipEventNID, senderMembership == tables.MembershipStateJoin, nil } func (d *Database) GetMembershipEventNIDsForRoom( ctx context.Context, roomNID types.RoomNID, joinOnly bool, localOnly bool, ) ([]types.EventNID, error) { if joinOnly { return d.MembershipTable.SelectMembershipsFromRoomAndMembership( ctx, roomNID, tables.MembershipStateJoin, localOnly, ) } return d.MembershipTable.SelectMembershipsFromRoom(ctx, roomNID, localOnly) } func (d *Database) GetInvitesForUser( ctx context.Context, roomNID types.RoomNID, targetUserNID types.EventStateKeyNID, ) (senderUserIDs []types.EventStateKeyNID, eventIDs []string, err error) { return d.InvitesTable.SelectInviteActiveForUserInRoom(ctx, targetUserNID, roomNID) } func (d *Database) Events( ctx context.Context, eventNIDs []types.EventNID, ) ([]types.Event, error) { eventJSONs, err := d.EventJSONTable.BulkSelectEventJSON(ctx, eventNIDs) if err != nil { return nil, err } results := make([]types.Event, len(eventJSONs)) for i, eventJSON := range eventJSONs { var roomNID types.RoomNID var roomVersion gomatrixserverlib.RoomVersion result := &results[i] result.EventNID = eventJSON.EventNID roomNID, err = d.EventsTable.SelectRoomNIDForEventNID(ctx, eventJSON.EventNID) if err != nil { return nil, err } roomVersion, err = d.RoomsTable.SelectRoomVersionForRoomNID(ctx, roomNID) if err != nil { return nil, err } result.Event, err = gomatrixserverlib.NewEventFromTrustedJSON( eventJSON.EventJSON, false, roomVersion, ) if err != nil { return nil, err } } if !redactionsArePermanent { d.applyRedactions(results) } return results, nil } func (d *Database) GetTransactionEventID( ctx context.Context, transactionID string, sessionID int64, userID string, ) (string, error) { eventID, err := d.TransactionsTable.SelectTransactionEventID(ctx, transactionID, sessionID, userID) if err == sql.ErrNoRows { return "", nil } return eventID, err } func (d *Database) MembershipUpdater( ctx context.Context, roomID, targetUserID string, targetLocal bool, roomVersion gomatrixserverlib.RoomVersion, ) (*MembershipUpdater, error) { txn, err := d.DB.Begin() if err != nil { return nil, err } var updater *MembershipUpdater _ = d.Writer.Do(d.DB, txn, func(txn *sql.Tx) error { updater, err = NewMembershipUpdater(ctx, d, txn, roomID, targetUserID, targetLocal, roomVersion) return nil }) return updater, err } func (d *Database) GetLatestEventsForUpdate( ctx context.Context, roomNID types.RoomNID, ) (*LatestEventsUpdater, error) { txn, err := d.DB.Begin() if err != nil { return nil, err } var updater *LatestEventsUpdater _ = d.Writer.Do(d.DB, txn, func(txn *sql.Tx) error { updater, err = NewLatestEventsUpdater(ctx, d, txn, roomNID) return nil }) return updater, err } // nolint:gocyclo func (d *Database) StoreEvent( ctx context.Context, event gomatrixserverlib.Event, txnAndSessionID *api.TransactionID, authEventNIDs []types.EventNID, ) (types.RoomNID, types.StateAtEvent, *gomatrixserverlib.Event, string, error) { var ( roomNID types.RoomNID eventTypeNID types.EventTypeNID eventStateKeyNID types.EventStateKeyNID eventNID types.EventNID stateNID types.StateSnapshotNID redactionEvent *gomatrixserverlib.Event redactedEventID string err error ) err = d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error { if txnAndSessionID != nil { if err = d.TransactionsTable.InsertTransaction( ctx, txn, txnAndSessionID.TransactionID, txnAndSessionID.SessionID, event.Sender(), event.EventID(), ); err != nil { return fmt.Errorf("d.TransactionsTable.InsertTransaction: %w", err) } } // TODO: Here we should aim to have two different code paths for new rooms // vs existing ones. // Get the default room version. If the client doesn't supply a room_version // then we will use our configured default to create the room. // https://matrix.org/docs/spec/client_server/r0.6.0#post-matrix-client-r0-createroom // Note that the below logic depends on the m.room.create event being the // first event that is persisted to the database when creating or joining a // room. var roomVersion gomatrixserverlib.RoomVersion if roomVersion, err = extractRoomVersionFromCreateEvent(event); err != nil { return fmt.Errorf("extractRoomVersionFromCreateEvent: %w", err) } if roomNID, err = d.assignRoomNID(ctx, txn, event.RoomID(), roomVersion); err != nil { return fmt.Errorf("d.assignRoomNID: %w", err) } if eventTypeNID, err = d.assignEventTypeNID(ctx, txn, event.Type()); err != nil { return fmt.Errorf("d.assignEventTypeNID: %w", err) } eventStateKey := event.StateKey() // Assigned a numeric ID for the state_key if there is one present. // Otherwise set the numeric ID for the state_key to 0. if eventStateKey != nil { if eventStateKeyNID, err = d.assignStateKeyNID(ctx, txn, *eventStateKey); err != nil { return fmt.Errorf("d.assignStateKeyNID: %w", err) } } if eventNID, stateNID, err = d.EventsTable.InsertEvent( ctx, txn, roomNID, eventTypeNID, eventStateKeyNID, event.EventID(), event.EventReference().EventSHA256, authEventNIDs, event.Depth(), ); err != nil { if err == sql.ErrNoRows { // We've already inserted the event so select the numeric event ID eventNID, stateNID, err = d.EventsTable.SelectEvent(ctx, txn, event.EventID()) } if err != nil { return err } } if err = d.EventJSONTable.InsertEventJSON(ctx, txn, eventNID, event.JSON()); err != nil { return fmt.Errorf("d.EventJSONTable.InsertEventJSON: %w", err) } redactionEvent, redactedEventID, err = d.handleRedactions(ctx, txn, eventNID, event) return nil }) if err != nil { return 0, types.StateAtEvent{}, nil, "", fmt.Errorf("d.Writer.Do: %w", err) } return roomNID, types.StateAtEvent{ BeforeStateSnapshotNID: stateNID, StateEntry: types.StateEntry{ StateKeyTuple: types.StateKeyTuple{ EventTypeNID: eventTypeNID, EventStateKeyNID: eventStateKeyNID, }, EventNID: eventNID, }, }, redactionEvent, redactedEventID, nil } func (d *Database) PublishRoom(ctx context.Context, roomID string, publish bool) error { return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error { return d.PublishedTable.UpsertRoomPublished(ctx, txn, roomID, publish) }) } func (d *Database) GetPublishedRooms(ctx context.Context) ([]string, error) { return d.PublishedTable.SelectAllPublishedRooms(ctx, true) } func (d *Database) assignRoomNID( ctx context.Context, txn *sql.Tx, roomID string, roomVersion gomatrixserverlib.RoomVersion, ) (types.RoomNID, error) { if roomNID, ok := d.Cache.GetRoomServerRoomNID(roomID); ok { return roomNID, nil } // Check if we already have a numeric ID in the database. roomNID, err := d.RoomsTable.SelectRoomNID(ctx, txn, roomID) if err == sql.ErrNoRows { // We don't have a numeric ID so insert one into the database. roomNID, err = d.RoomsTable.InsertRoomNID(ctx, txn, roomID, roomVersion) if err == sql.ErrNoRows { // We raced with another insert so run the select again. roomNID, err = d.RoomsTable.SelectRoomNID(ctx, txn, roomID) } } if err == nil { d.Cache.StoreRoomServerRoomNID(roomID, roomNID) } return roomNID, err } func (d *Database) assignEventTypeNID( ctx context.Context, txn *sql.Tx, eventType string, ) (types.EventTypeNID, error) { if eventTypeNID, ok := d.Cache.GetRoomServerEventTypeNID(eventType); ok { return eventTypeNID, nil } // Check if we already have a numeric ID in the database. eventTypeNID, err := d.EventTypesTable.SelectEventTypeNID(ctx, txn, eventType) if err == sql.ErrNoRows { // We don't have a numeric ID so insert one into the database. eventTypeNID, err = d.EventTypesTable.InsertEventTypeNID(ctx, txn, eventType) if err == sql.ErrNoRows { // We raced with another insert so run the select again. eventTypeNID, err = d.EventTypesTable.SelectEventTypeNID(ctx, txn, eventType) } } if err == nil { d.Cache.StoreRoomServerEventTypeNID(eventType, eventTypeNID) } return eventTypeNID, err } func (d *Database) assignStateKeyNID( ctx context.Context, txn *sql.Tx, eventStateKey string, ) (types.EventStateKeyNID, error) { if eventStateKeyNID, ok := d.Cache.GetRoomServerStateKeyNID(eventStateKey); ok { return eventStateKeyNID, nil } // Check if we already have a numeric ID in the database. eventStateKeyNID, err := d.EventStateKeysTable.SelectEventStateKeyNID(ctx, txn, eventStateKey) if err == sql.ErrNoRows { // We don't have a numeric ID so insert one into the database. eventStateKeyNID, err = d.EventStateKeysTable.InsertEventStateKeyNID(ctx, txn, eventStateKey) if err == sql.ErrNoRows { // We raced with another insert so run the select again. eventStateKeyNID, err = d.EventStateKeysTable.SelectEventStateKeyNID(ctx, txn, eventStateKey) } } if err == nil { d.Cache.StoreRoomServerStateKeyNID(eventStateKey, eventStateKeyNID) } return eventStateKeyNID, err } func extractRoomVersionFromCreateEvent(event gomatrixserverlib.Event) ( gomatrixserverlib.RoomVersion, error, ) { var err error var roomVersion gomatrixserverlib.RoomVersion // Look for m.room.create events. if event.Type() != gomatrixserverlib.MRoomCreate { return gomatrixserverlib.RoomVersion(""), nil } roomVersion = gomatrixserverlib.RoomVersionV1 var createContent gomatrixserverlib.CreateContent // The m.room.create event contains an optional "room_version" key in // the event content, so we need to unmarshal that first. if err = json.Unmarshal(event.Content(), &createContent); err != nil { return gomatrixserverlib.RoomVersion(""), err } // A room version was specified in the event content? if createContent.RoomVersion != nil { roomVersion = gomatrixserverlib.RoomVersion(*createContent.RoomVersion) } return roomVersion, err } // handleRedactions manages the redacted status of events. There's two cases to consider in order to comply with the spec: // "servers should not apply or send redactions to clients until both the redaction event and original event have been seen, and are valid." // https://matrix.org/docs/spec/rooms/v3#authorization-rules-for-events // These cases are: // - This is a redaction event, redact the event it references if we know about it. // - This is a normal event which may have been previously redacted. // In the first case, check if we have the referenced event then apply the redaction, else store it // in the redactions table with validated=FALSE. In the second case, check if there is a redaction for it: // if there is then apply the redactions and set validated=TRUE. // // When an event is redacted, the redacted event JSON is modified to add an `unsigned.redacted_because` field. We use this field // when loading events to determine whether to apply redactions. This keeps the hot-path of reading events quick as we don't need // to cross-reference with other tables when loading. // // Returns the redaction event and the event ID of the redacted event if this call resulted in a redaction. func (d *Database) handleRedactions( ctx context.Context, txn *sql.Tx, eventNID types.EventNID, event gomatrixserverlib.Event, ) (*gomatrixserverlib.Event, string, error) { var err error isRedactionEvent := event.Type() == gomatrixserverlib.MRoomRedaction && event.StateKey() == nil if isRedactionEvent { // an event which redacts itself should be ignored if event.EventID() == event.Redacts() { return nil, "", nil } err = d.RedactionsTable.InsertRedaction(ctx, txn, tables.RedactionInfo{ Validated: false, RedactionEventID: event.EventID(), RedactsEventID: event.Redacts(), }) if err != nil { return nil, "", err } } redactionEvent, redactedEvent, validated, err := d.loadRedactionPair(ctx, txn, eventNID, event) if err != nil { return nil, "", err } if validated || redactedEvent == nil || redactionEvent == nil { // we've seen this redaction before or there is nothing to redact return nil, "", nil } if redactedEvent.RoomID() != redactionEvent.RoomID() { // redactions across rooms aren't allowed return nil, "", nil } // mark the event as redacted err = redactedEvent.SetUnsignedField("redacted_because", redactionEvent) if err != nil { return nil, "", err } if redactionsArePermanent { redactedEvent.Event = redactedEvent.Redact() } // overwrite the eventJSON table err = d.EventJSONTable.InsertEventJSON(ctx, txn, redactedEvent.EventNID, redactedEvent.JSON()) if err != nil { return nil, "", err } return &redactionEvent.Event, redactedEvent.EventID(), d.RedactionsTable.MarkRedactionValidated(ctx, txn, redactionEvent.EventID(), true) } // loadRedactionPair returns both the redaction event and the redacted event, else nil. func (d *Database) loadRedactionPair( ctx context.Context, txn *sql.Tx, eventNID types.EventNID, event gomatrixserverlib.Event, ) (*types.Event, *types.Event, bool, error) { var redactionEvent, redactedEvent *types.Event var info *tables.RedactionInfo var err error isRedactionEvent := event.Type() == gomatrixserverlib.MRoomRedaction && event.StateKey() == nil var eventBeingRedacted string if isRedactionEvent { eventBeingRedacted = event.Redacts() redactionEvent = &types.Event{ EventNID: eventNID, Event: event, } } else { eventBeingRedacted = event.EventID() // maybe, we'll see if we have info redactedEvent = &types.Event{ EventNID: eventNID, Event: event, } } info, err = d.RedactionsTable.SelectRedactionInfoByEventBeingRedacted(ctx, txn, eventBeingRedacted) if err != nil { return nil, nil, false, err } if info == nil { // this event hasn't been redacted or we don't have the redaction for it yet return nil, nil, false, nil } if isRedactionEvent { redactedEvent = d.loadEvent(ctx, info.RedactsEventID) } else { redactionEvent = d.loadEvent(ctx, info.RedactionEventID) } return redactionEvent, redactedEvent, info.Validated, nil } // applyRedactions will redact events that have an `unsigned.redacted_because` field. func (d *Database) applyRedactions(events []types.Event) { for i := range events { if result := gjson.GetBytes(events[i].Unsigned(), "redacted_because"); result.Exists() { events[i].Event = events[i].Redact() } } } // loadEvent loads a single event or returns nil on any problems/missing event func (d *Database) loadEvent(ctx context.Context, eventID string) *types.Event { nids, err := d.EventNIDs(ctx, []string{eventID}) if err != nil { return nil } if len(nids) == 0 { return nil } evs, err := d.Events(ctx, []types.EventNID{nids[eventID]}) if err != nil { return nil } if len(evs) != 1 { return nil } return &evs[0] }