From 3a66d3c6cf7cee534bdb3fb4f0c7c8bd27ac89eb Mon Sep 17 00:00:00 2001
From: Will Hunt <willh@matrix.org>
Date: Tue, 5 Jan 2021 10:56:09 +0000
Subject: [PATCH] Hit appservice when trying to join a non-existent alias

---
 roomserver/internal/api.go                  |  1 +
 roomserver/internal/perform/perform_join.go | 11 ++++++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/roomserver/internal/api.go b/roomserver/internal/api.go
index 91caa0bdc..c04a4ccd0 100644
--- a/roomserver/internal/api.go
+++ b/roomserver/internal/api.go
@@ -88,6 +88,7 @@ func (r *RoomserverInternalAPI) SetFederationSenderAPI(fsAPI fsAPI.FederationSen
 		Cfg:        r.Cfg,
 		DB:         r.DB,
 		FSAPI:      r.fsAPI,
+		RSAPI:      r,
 		Inputer:    r.Inputer,
 	}
 	r.Peeker = &perform.Peeker{
diff --git a/roomserver/internal/perform/perform_join.go b/roomserver/internal/perform/perform_join.go
index 8eb6b648e..7f0020a5c 100644
--- a/roomserver/internal/perform/perform_join.go
+++ b/roomserver/internal/perform/perform_join.go
@@ -24,18 +24,21 @@ import (
 	fsAPI "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/internal/eventutil"
 	"github.com/matrix-org/dendrite/roomserver/api"
+	rsAPI "github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/roomserver/internal/helpers"
 	"github.com/matrix-org/dendrite/roomserver/internal/input"
 	"github.com/matrix-org/dendrite/roomserver/storage"
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/sirupsen/logrus"
+	log "github.com/sirupsen/logrus"
 )
 
 type Joiner struct {
 	ServerName gomatrixserverlib.ServerName
 	Cfg        *config.RoomServer
 	FSAPI      fsAPI.FederationSenderInternalAPI
+	RSAPI      rsAPI.RoomserverInternalAPI
 	DB         storage.Database
 
 	Inputer *input.Inputer
@@ -121,11 +124,17 @@ func (r *Joiner) performJoinRoomByAlias(
 		roomID = dirRes.RoomID
 		req.ServerNames = append(req.ServerNames, dirRes.ServerNames...)
 	} else {
+		var getRoomReq = rsAPI.GetRoomIDForAliasRequest{
+			Alias:               req.RoomIDOrAlias,
+			ShouldHitAppservice: true,
+		}
+		var getRoomRes = rsAPI.GetRoomIDForAliasResponse{}
 		// Otherwise, look up if we know this room alias locally.
-		roomID, err = r.DB.GetRoomIDForAlias(ctx, req.RoomIDOrAlias)
+		err = r.RSAPI.GetRoomIDForAlias(ctx, &getRoomReq, &getRoomRes)
 		if err != nil {
 			return "", "", fmt.Errorf("Lookup room alias %q failed: %w", req.RoomIDOrAlias, err)
 		}
+		roomID = getRoomRes.RoomID
 	}
 
 	// If the room ID is empty then we failed to look up the alias.