From da6a8b6f897a7f3f19f3ff0e970d5414500a2e96 Mon Sep 17 00:00:00 2001
From: PiotrKozimor <37144818+PiotrKozimor@users.noreply.github.com>
Date: Thu, 4 Aug 2022 16:39:58 +0200
Subject: [PATCH] Allow to get event by ID if membership is joined or invited
 (#20)

* Allow to get event by ID if membership is joined or invited

* Fix linter errors

* Use own fork of complement
---
 .github/workflows/dendrite.yml |  2 +-
 clientapi/routing/getevent.go  | 31 ++++++++++++++++++++++++++-----
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/dendrite.yml b/.github/workflows/dendrite.yml
index 9b6628641..83a5389ed 100644
--- a/.github/workflows/dendrite.yml
+++ b/.github/workflows/dendrite.yml
@@ -285,7 +285,7 @@ jobs:
               continue
             fi
 
-            (wget -O - "https://github.com/matrix-org/complement/archive/$BRANCH_NAME.tar.gz" | tar -xz --strip-components=1 -C complement) && break
+            (wget -O - "https://github.com/globekeeper/complement/archive/$BRANCH_NAME.tar.gz" | tar -xz --strip-components=1 -C complement) && break
           done
 
       # Build initial Dendrite image
diff --git a/clientapi/routing/getevent.go b/clientapi/routing/getevent.go
index f44790689..836935ca8 100644
--- a/clientapi/routing/getevent.go
+++ b/clientapi/routing/getevent.go
@@ -82,7 +82,7 @@ func GetEvent(
 		}},
 	}
 	var stateResp api.QueryStateAfterEventsResponse
-	if err := rsAPI.QueryStateAfterEvents(req.Context(), &stateReq, &stateResp); err != nil {
+	if err = rsAPI.QueryStateAfterEvents(req.Context(), &stateReq, &stateResp); err != nil {
 		util.GetLogger(req.Context()).WithError(err).Error("queryAPI.QueryStateAfterEvents failed")
 		return jsonerror.InternalServerError()
 	}
@@ -118,7 +118,8 @@ func GetEvent(
 		} else if !stateEvent.StateKeyEquals(device.UserID) {
 			continue
 		}
-		membership, err := stateEvent.Membership()
+		var membership string
+		membership, err = stateEvent.Membership()
 		if err != nil {
 			util.GetLogger(req.Context()).WithError(err).Error("stateEvent.Membership failed")
 			return jsonerror.InternalServerError()
@@ -131,8 +132,28 @@ func GetEvent(
 		}
 	}
 
-	return util.JSONResponse{
-		Code: http.StatusNotFound,
-		JSON: jsonerror.NotFound("The event was not found or you do not have permission to read this event"),
+	// we might fail to retrieve correct state above, let's check user membership and allow to fetch event if they are invited or joined, since we always use m.room.history_visibility shared.
+	var membershipRes api.QueryMembershipForUserResponse
+	ctx := req.Context()
+	err = rsAPI.QueryMembershipForUser(ctx, &api.QueryMembershipForUserRequest{
+		RoomID: roomID,
+		UserID: device.UserID,
+	}, &membershipRes)
+	if err != nil {
+		util.GetLogger(ctx).WithError(err).Error("Failed to QueryMembershipForUser")
+		return jsonerror.InternalServerError()
+	}
+	// If the user has never been in the room then stop at this point.
+	// We won't tell the user about a room they have never joined.
+	if !membershipRes.HasBeenInRoom && membershipRes.Membership != gomatrixserverlib.Invite || membershipRes.Membership == gomatrixserverlib.Ban {
+		return util.JSONResponse{
+			Code: http.StatusNotFound,
+			JSON: jsonerror.NotFound("The event was not found or you do not have permission to read this event"),
+		}
+	} else {
+		return util.JSONResponse{
+			Code: http.StatusOK,
+			JSON: gomatrixserverlib.ToClientEvent(r.requestedEvent, gomatrixserverlib.FormatAll),
+		}
 	}
 }