From 41b6bf56e5ed2202071d738f5f64e491d8496739 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Mon, 23 May 2022 12:36:33 +0100
Subject: [PATCH] Add `Resident` flag to `QueryRestrictedJoinAllowedResponse`

---
 roomserver/api/query.go            |  3 ++-
 roomserver/internal/query/query.go | 19 ++++++++++---------
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/roomserver/api/query.go b/roomserver/api/query.go
index e6460ab21..33a235829 100644
--- a/roomserver/api/query.go
+++ b/roomserver/api/query.go
@@ -354,7 +354,8 @@ type QueryRestrictedJoinAllowedRequest struct {
 }
 
 type QueryRestrictedJoinAllowedResponse struct {
-	Allowed bool `json:"allowed"`
+	Resident bool `json:"resident"` // Is our homeserver in the relevant rooms?
+	Allowed  bool `json:"allowed"`  // Is the join allowed by the rules?
 }
 
 // MarshalJSON stringifies the room ID and StateKeyTuple keys so they can be sent over the wire in HTTP API mode.
diff --git a/roomserver/internal/query/query.go b/roomserver/internal/query/query.go
index 103f1cb86..5b37c4185 100644
--- a/roomserver/internal/query/query.go
+++ b/roomserver/internal/query/query.go
@@ -790,6 +790,10 @@ func (r *Queryer) QueryRestrictedJoinAllowed(ctx context.Context, req *api.Query
 	if joinRules.JoinRule != gomatrixserverlib.Restricted {
 		return nil
 	}
+	// Start off by populating the "resident" flag in the response. If we
+	// come across any rooms in the request that are missing, we will unset
+	// the flag.
+	res.Resident = true
 	// Step through the join rules and see if the user matches any of them.
 	for _, rule := range joinRules.Allow {
 		// We only understand "m.room_membership" rules at this point in
@@ -800,21 +804,17 @@ func (r *Queryer) QueryRestrictedJoinAllowed(ctx context.Context, req *api.Query
 		// See if the room exists. If it doesn't exist or if it's a stub
 		// room entry then we can't check memberships.
 		targetRoomInfo, err := r.DB.RoomInfo(ctx, rule.RoomID)
-		if err != nil {
-			continue
-		}
-		if targetRoomInfo == nil || targetRoomInfo.IsStub {
+		if err != nil || targetRoomInfo == nil || targetRoomInfo.IsStub {
+			res.Resident = false
 			continue
 		}
 		// First of all work out if *we* are still in the room, otherwise
 		// it's possible that the memberships will be out of date.
 		isIn, err := r.DB.GetLocalServerInRoom(ctx, targetRoomInfo.RoomNID)
-		if err != nil {
-			continue
-		}
-		if !isIn {
-			// We aren't in the room, so we can no longer tell if the room
+		if err != nil || !isIn {
+			// If we aren't in the room, we can no longer tell if the room
 			// memberships are up-to-date.
+			res.Resident = false
 			continue
 		}
 		// At this point we're happy that we are in the room, so now let's
@@ -825,6 +825,7 @@ func (r *Queryer) QueryRestrictedJoinAllowed(ctx context.Context, req *api.Query
 		}
 		// If the user is in the room then we will allow the membership.
 		if isIn {
+			res.Resident = true
 			res.Allowed = true
 			return nil
 		}