1 files changed, 59 insertions, 2 deletions
diff --git a/roomserver/internal/alias.go b/roomserver/internal/alias.go
index 7995279d..5c1c04f0 100644
--- a/roomserver/internal/alias.go
+++ b/roomserver/internal/alias.go
@@ -16,12 +16,18 @@ package internal
 
 import (
 	"context"
+	"database/sql"
+	"errors"
 	"fmt"
+	"time"
 
+	asAPI "github.com/matrix-org/dendrite/appservice/api"
+	"github.com/matrix-org/dendrite/internal/eventutil"
 	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/dendrite/roomserver/internal/helpers"
 	"github.com/matrix-org/gomatrixserverlib"
-
-	asAPI "github.com/matrix-org/dendrite/appservice/api"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
 )
 
 // RoomserverInternalAPIDatabase has the storage APIs needed to implement the alias API.
@@ -183,6 +189,57 @@ func (r *RoomserverInternalAPI) RemoveRoomAlias(
 		}
 	}
 
+	ev, err := r.DB.GetStateEvent(ctx, roomID, gomatrixserverlib.MRoomCanonicalAlias, "")
+	if err != nil && err != sql.ErrNoRows {
+		return err
+	} else if ev != nil {
+		stateAlias := gjson.GetBytes(ev.Content(), "alias").Str
+		// the alias to remove is currently set as the canonical alias, remove it
+		if stateAlias == request.Alias {
+			res, err := sjson.DeleteBytes(ev.Content(), "alias")
+			if err != nil {
+				return err
+			}
+
+			sender := request.UserID
+			if request.UserID != ev.Sender() {
+				sender = ev.Sender()
+			}
+
+			builder := &gomatrixserverlib.EventBuilder{
+				Sender:   sender,
+				RoomID:   ev.RoomID(),
+				Type:     ev.Type(),
+				StateKey: ev.StateKey(),
+				Content:  res,
+			}
+
+			eventsNeeded, err := gomatrixserverlib.StateNeededForEventBuilder(builder)
+			if err != nil {
+				return fmt.Errorf("gomatrixserverlib.StateNeededForEventBuilder: %w", err)
+			}
+			if len(eventsNeeded.Tuples()) == 0 {
+				return errors.New("expecting state tuples for event builder, got none")
+			}
+
+			stateRes := &api.QueryLatestEventsAndStateResponse{}
+			if err := helpers.QueryLatestEventsAndState(ctx, r.DB, &api.QueryLatestEventsAndStateRequest{RoomID: roomID, StateToFetch: eventsNeeded.Tuples()}, stateRes); err != nil {
+				return err
+			}
+
+			newEvent, err := eventutil.BuildEvent(ctx, builder, r.Cfg.Matrix, time.Now(), &eventsNeeded, stateRes)
+			if err != nil {
+				return err
+			}
+
+			err = api.SendEvents(ctx, r.RSAPI, api.KindNew, []*gomatrixserverlib.HeaderedEvent{newEvent}, r.ServerName, r.ServerName, nil, false)
+			if err != nil {
+				return err
+			}
+
+		}
+	}
+
 	// Remove the alias from the database
 	if err := r.DB.RemoveRoomAlias(ctx, request.Alias); err != nil {
 		return err