From 6cdfaa2b6b9c7ee5a4213431ab3de0da95ae3e9f Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Wed, 24 May 2023 19:18:18 +0200
Subject: [PATCH 01/12] Move send_leave to GMSL

---
 federationapi/routing/leave.go     | 170 ++++-------------------------
 roomserver/api/api.go              |   1 +
 roomserver/internal/query/query.go |  24 ++++
 3 files changed, 48 insertions(+), 147 deletions(-)

diff --git a/federationapi/routing/leave.go b/federationapi/routing/leave.go
index 3e576e09c6..aa7f693606 100644
--- a/federationapi/routing/leave.go
+++ b/federationapi/routing/leave.go
@@ -165,165 +165,41 @@ func SendLeave(
 		}
 	}
 
-	verImpl, err := gomatrixserverlib.GetRoomVersion(roomVersion)
-	if err != nil {
-		return util.JSONResponse{
-			Code: http.StatusInternalServerError,
-			JSON: spec.UnsupportedRoomVersion(
-				fmt.Sprintf("QueryRoomVersionForRoom returned unknown version: %s", roomVersion),
-			),
-		}
-	}
+	event, err := gomatrixserverlib.HandleSendLeave(
+		httpReq.Context(), request.Content(), request.Origin(), roomVersion, eventID, roomID, rsAPI, keys,
+	)
 
-	// Decode the event JSON from the request.
-	event, err := verImpl.NewEventFromUntrustedJSON(request.Content())
-	switch err.(type) {
-	case gomatrixserverlib.BadJSONError:
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON(err.Error()),
-		}
+	switch e := err.(type) {
 	case nil:
-	default:
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.NotJSON("The request body could not be decoded into valid JSON. " + err.Error()),
-		}
-	}
-
-	// Check that the room ID is correct.
-	if event.RoomID() != roomID {
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("The room ID in the request path must match the room ID in the leave event JSON"),
-		}
-	}
-
-	// Check that the event ID is correct.
-	if event.EventID() != eventID {
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("The event ID in the request path must match the event ID in the leave event JSON"),
-		}
-	}
-
-	if event.StateKey() == nil || event.StateKeyEquals("") {
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("No state key was provided in the leave event."),
-		}
-	}
-	if !event.StateKeyEquals(event.Sender()) {
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("Event state key must match the event sender."),
-		}
-	}
-
-	// Check that the sender belongs to the server that is sending us
-	// the request. By this point we've already asserted that the sender
-	// and the state key are equal so we don't need to check both.
-	var serverName spec.ServerName
-	if _, serverName, err = gomatrixserverlib.SplitID('@', event.Sender()); err != nil {
-		return util.JSONResponse{
-			Code: http.StatusForbidden,
-			JSON: spec.Forbidden("The sender of the join is invalid"),
-		}
-	} else if serverName != request.Origin() {
-		return util.JSONResponse{
-			Code: http.StatusForbidden,
-			JSON: spec.Forbidden("The sender does not match the server that originated the request"),
-		}
-	}
-
-	// Check if the user has already left. If so, no-op!
-	queryReq := &api.QueryLatestEventsAndStateRequest{
-		RoomID: roomID,
-		StateToFetch: []gomatrixserverlib.StateKeyTuple{
-			{
-				EventType: spec.MRoomMember,
-				StateKey:  *event.StateKey(),
-			},
-		},
-	}
-	queryRes := &api.QueryLatestEventsAndStateResponse{}
-	err = rsAPI.QueryLatestEventsAndState(httpReq.Context(), queryReq, queryRes)
-	if err != nil {
-		util.GetLogger(httpReq.Context()).WithError(err).Error("rsAPI.QueryLatestEventsAndState failed")
-		return util.JSONResponse{
-			Code: http.StatusInternalServerError,
-			JSON: spec.InternalServerError{},
-		}
-	}
-	// The room doesn't exist or we weren't ever joined to it. Might as well
-	// no-op here.
-	if !queryRes.RoomExists || len(queryRes.StateEvents) == 0 {
-		return util.JSONResponse{
-			Code: http.StatusOK,
-			JSON: struct{}{},
-		}
-	}
-	// Check if we're recycling a previous leave event.
-	if event.EventID() == queryRes.StateEvents[0].EventID() {
-		return util.JSONResponse{
-			Code: http.StatusOK,
-			JSON: struct{}{},
-		}
-	}
-	// We are/were joined/invited/banned or something. Check if
-	// we can no-op here.
-	if len(queryRes.StateEvents) == 1 {
-		if mem, merr := queryRes.StateEvents[0].Membership(); merr == nil && mem == spec.Leave {
-			return util.JSONResponse{
-				Code: http.StatusOK,
-				JSON: struct{}{},
-			}
-		}
-	}
-
-	// Check that the event is signed by the server sending the request.
-	redacted, err := verImpl.RedactEventJSON(event.JSON())
-	if err != nil {
-		logrus.WithError(err).Errorf("XXX: leave.go")
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("The event JSON could not be redacted"),
-		}
-	}
-	verifyRequests := []gomatrixserverlib.VerifyJSONRequest{{
-		ServerName:             serverName,
-		Message:                redacted,
-		AtTS:                   event.OriginServerTS(),
-		StrictValidityChecking: true,
-	}}
-	verifyResults, err := keys.VerifyJSONs(httpReq.Context(), verifyRequests)
-	if err != nil {
-		util.GetLogger(httpReq.Context()).WithError(err).Error("keys.VerifyJSONs failed")
+	case spec.InternalServerError:
+		util.GetLogger(httpReq.Context()).WithError(err).Error("failed to handle send_leave request")
 		return util.JSONResponse{
 			Code: http.StatusInternalServerError,
 			JSON: spec.InternalServerError{},
 		}
-	}
-	if verifyResults[0].Error != nil {
-		return util.JSONResponse{
-			Code: http.StatusForbidden,
-			JSON: spec.Forbidden("The leave must be signed by the server it originated on"),
+	case spec.MatrixError:
+		util.GetLogger(httpReq.Context()).WithError(err).Error("failed to handle send_leave request")
+		code := http.StatusInternalServerError
+		switch e.ErrCode {
+		case spec.ErrorForbidden:
+			code = http.StatusForbidden
+		case spec.ErrorNotFound:
+			code = http.StatusNotFound
+		case spec.ErrorUnsupportedRoomVersion:
+			code = http.StatusInternalServerError
+		case spec.ErrorBadJSON:
+			code = http.StatusBadRequest
 		}
-	}
 
-	// check membership is set to leave
-	mem, err := event.Membership()
-	if err != nil {
-		util.GetLogger(httpReq.Context()).WithError(err).Error("event.Membership failed")
 		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("missing content.membership key"),
+			Code: code,
+			JSON: e,
 		}
-	}
-	if mem != spec.Leave {
+	default:
+		util.GetLogger(httpReq.Context()).WithError(err).Error("failed to handle send_leave request")
 		return util.JSONResponse{
 			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("The membership in the event content must be set to leave"),
+			JSON: spec.Unknown("unknown error"),
 		}
 	}
 
diff --git a/roomserver/api/api.go b/roomserver/api/api.go
index 213e16e5df..0627770f5e 100644
--- a/roomserver/api/api.go
+++ b/roomserver/api/api.go
@@ -197,6 +197,7 @@ type UserRoomserverAPI interface {
 }
 
 type FederationRoomserverAPI interface {
+	gomatrixserverlib.LatestStateQuerier
 	InputRoomEventsAPI
 	QueryLatestEventsAndStateAPI
 	QueryBulkStateContentAPI
diff --git a/roomserver/internal/query/query.go b/roomserver/internal/query/query.go
index effcc90d7e..c81692ce17 100644
--- a/roomserver/internal/query/query.go
+++ b/roomserver/internal/query/query.go
@@ -55,6 +55,30 @@ func (r *Queryer) QueryLatestEventsAndState(
 	return helpers.QueryLatestEventsAndState(ctx, r.DB, request, response)
 }
 
+func (r *Queryer) LatestState(
+	ctx context.Context, roomID spec.RoomID, userID spec.UserID,
+) ([]gomatrixserverlib.PDU, error) {
+	request := &api.QueryLatestEventsAndStateRequest{
+		RoomID: roomID.String(),
+		StateToFetch: []gomatrixserverlib.StateKeyTuple{
+			{
+				EventType: spec.MRoomMember,
+				StateKey:  userID.String(),
+			},
+		},
+	}
+	response := &api.QueryLatestEventsAndStateResponse{}
+	err := helpers.QueryLatestEventsAndState(ctx, r.DB, request, response)
+	if err != nil {
+		return nil, err
+	}
+	res := make([]gomatrixserverlib.PDU, 0, len(response.StateEvents))
+	for _, ev := range response.StateEvents {
+		res = append(res, ev.PDU)
+	}
+	return res, nil
+}
+
 // QueryStateAfterEvents implements api.RoomserverInternalAPI
 func (r *Queryer) QueryStateAfterEvents(
 	ctx context.Context,

From 254d53578986115ed856e9040fe3852f9eda862c Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Fri, 26 May 2023 10:30:57 +0200
Subject: [PATCH 02/12] Update GMSL

---
 go.mod | 2 +-
 go.sum | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index 16e5adc8c8..55851fbe63 100644
--- a/go.mod
+++ b/go.mod
@@ -22,7 +22,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20230524095531-95ba6c68efb6
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20230525131408-9e1377a918b6
 	github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a
 	github.com/matrix-org/util v0.0.0-20221111132719-399730281e66
 	github.com/mattn/go-sqlite3 v1.14.16
diff --git a/go.sum b/go.sum
index 98e7e839df..05e4b7d7ca 100644
--- a/go.sum
+++ b/go.sum
@@ -323,8 +323,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91 h1:s7fexw
 github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91/go.mod h1:e+cg2q7C7yE5QnAXgzo512tgFh1RbQLC0+jozuegKgo=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530 h1:kHKxCOLcHH8r4Fzarl4+Y3K5hjothkVW5z7T1dUM11U=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230524095531-95ba6c68efb6 h1:FQpdh/KGCCQJytz4GAdG6pbx3DJ1HNzdKFc/BCZ0hP0=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230524095531-95ba6c68efb6/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230525131408-9e1377a918b6 h1:GZJdDQt/IJynQyWpHsYYWQUyCu9Y+asAdwfL7pJNQHU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230525131408-9e1377a918b6/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a h1:awrPDf9LEFySxTLKYBMCiObelNx/cBuv/wzllvCCH3A=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a/go.mod h1:HchJX9oKMXaT2xYFs0Ha/6Zs06mxLU8k6F1ODnrGkeQ=
 github.com/matrix-org/util v0.0.0-20221111132719-399730281e66 h1:6z4KxomXSIGWqhHcfzExgkH3Z3UkIXry4ibJS4Aqz2Y=

From 1e73175e27972ac0c49360267770cec64905310e Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Tue, 30 May 2023 18:01:19 +0200
Subject: [PATCH 03/12] Remove LatestState

---
 go.mod                             |  2 +-
 go.sum                             |  2 ++
 roomserver/api/api.go              |  1 -
 roomserver/internal/query/query.go | 24 ------------------------
 4 files changed, 3 insertions(+), 26 deletions(-)

diff --git a/go.mod b/go.mod
index 55851fbe63..521c98d70c 100644
--- a/go.mod
+++ b/go.mod
@@ -22,7 +22,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20230525131408-9e1377a918b6
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20230530160030-2640a7efaaaa
 	github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a
 	github.com/matrix-org/util v0.0.0-20221111132719-399730281e66
 	github.com/mattn/go-sqlite3 v1.14.16
diff --git a/go.sum b/go.sum
index 05e4b7d7ca..1d7518fadb 100644
--- a/go.sum
+++ b/go.sum
@@ -325,6 +325,8 @@ github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530 h1:kHKxCOLcHH8
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20230525131408-9e1377a918b6 h1:GZJdDQt/IJynQyWpHsYYWQUyCu9Y+asAdwfL7pJNQHU=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20230525131408-9e1377a918b6/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230530160030-2640a7efaaaa h1:m0wWaq2qvMJdYrj5p/mLXV11gbFEKNd6o7C16poSlW0=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230530160030-2640a7efaaaa/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a h1:awrPDf9LEFySxTLKYBMCiObelNx/cBuv/wzllvCCH3A=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a/go.mod h1:HchJX9oKMXaT2xYFs0Ha/6Zs06mxLU8k6F1ODnrGkeQ=
 github.com/matrix-org/util v0.0.0-20221111132719-399730281e66 h1:6z4KxomXSIGWqhHcfzExgkH3Z3UkIXry4ibJS4Aqz2Y=
diff --git a/roomserver/api/api.go b/roomserver/api/api.go
index 0627770f5e..213e16e5df 100644
--- a/roomserver/api/api.go
+++ b/roomserver/api/api.go
@@ -197,7 +197,6 @@ type UserRoomserverAPI interface {
 }
 
 type FederationRoomserverAPI interface {
-	gomatrixserverlib.LatestStateQuerier
 	InputRoomEventsAPI
 	QueryLatestEventsAndStateAPI
 	QueryBulkStateContentAPI
diff --git a/roomserver/internal/query/query.go b/roomserver/internal/query/query.go
index c81692ce17..effcc90d7e 100644
--- a/roomserver/internal/query/query.go
+++ b/roomserver/internal/query/query.go
@@ -55,30 +55,6 @@ func (r *Queryer) QueryLatestEventsAndState(
 	return helpers.QueryLatestEventsAndState(ctx, r.DB, request, response)
 }
 
-func (r *Queryer) LatestState(
-	ctx context.Context, roomID spec.RoomID, userID spec.UserID,
-) ([]gomatrixserverlib.PDU, error) {
-	request := &api.QueryLatestEventsAndStateRequest{
-		RoomID: roomID.String(),
-		StateToFetch: []gomatrixserverlib.StateKeyTuple{
-			{
-				EventType: spec.MRoomMember,
-				StateKey:  userID.String(),
-			},
-		},
-	}
-	response := &api.QueryLatestEventsAndStateResponse{}
-	err := helpers.QueryLatestEventsAndState(ctx, r.DB, request, response)
-	if err != nil {
-		return nil, err
-	}
-	res := make([]gomatrixserverlib.PDU, 0, len(response.StateEvents))
-	for _, ev := range response.StateEvents {
-		res = append(res, ev.PDU)
-	}
-	return res, nil
-}
-
 // QueryStateAfterEvents implements api.RoomserverInternalAPI
 func (r *Queryer) QueryStateAfterEvents(
 	ctx context.Context,

From 246836517cfdb309450361a549a1fb78dc3bce26 Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Wed, 31 May 2023 10:39:19 +0200
Subject: [PATCH 04/12] Fix unused stateKey variable

---
 roomserver/internal/query/query.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/roomserver/internal/query/query.go b/roomserver/internal/query/query.go
index effcc90d7e..9b520aa5cb 100644
--- a/roomserver/internal/query/query.go
+++ b/roomserver/internal/query/query.go
@@ -868,7 +868,7 @@ func (r *Queryer) QueryRoomInfo(ctx context.Context, roomID spec.RoomID) (*types
 }
 
 func (r *Queryer) CurrentStateEvent(ctx context.Context, roomID spec.RoomID, eventType string, stateKey string) (gomatrixserverlib.PDU, error) {
-	res, err := r.DB.GetStateEvent(ctx, roomID.String(), eventType, "")
+	res, err := r.DB.GetStateEvent(ctx, roomID.String(), eventType, stateKey)
 	if res == nil {
 		return nil, err
 	}

From 478a6339809f923550901f27063c9bf6659c7e17 Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Thu, 1 Jun 2023 13:32:10 +0200
Subject: [PATCH 05/12] Update GMSL

---
 go.mod | 2 +-
 go.sum | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index a20757bbcc..8906b8c66b 100644
--- a/go.mod
+++ b/go.mod
@@ -22,7 +22,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20230531155817-0e3adf17bee6
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20230601112942-5d099f949e82
 	github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a
 	github.com/matrix-org/util v0.0.0-20221111132719-399730281e66
 	github.com/mattn/go-sqlite3 v1.14.16
diff --git a/go.sum b/go.sum
index a1946adaaf..0060419f24 100644
--- a/go.sum
+++ b/go.sum
@@ -323,8 +323,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91 h1:s7fexw
 github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91/go.mod h1:e+cg2q7C7yE5QnAXgzo512tgFh1RbQLC0+jozuegKgo=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530 h1:kHKxCOLcHH8r4Fzarl4+Y3K5hjothkVW5z7T1dUM11U=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230531155817-0e3adf17bee6 h1:Kh1TNvJDhWN5CdgtICNUC4G0wV2km51LGr46Dvl153A=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230531155817-0e3adf17bee6/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230601112942-5d099f949e82 h1:VC9MCGI47z3ksNQt/sTcnwO//syibxgyz/6ckD6BjkY=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230601112942-5d099f949e82/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a h1:awrPDf9LEFySxTLKYBMCiObelNx/cBuv/wzllvCCH3A=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a/go.mod h1:HchJX9oKMXaT2xYFs0Ha/6Zs06mxLU8k6F1ODnrGkeQ=
 github.com/matrix-org/util v0.0.0-20221111132719-399730281e66 h1:6z4KxomXSIGWqhHcfzExgkH3Z3UkIXry4ibJS4Aqz2Y=

From 94d2074eb52d7099f3fae6fbba7c48f8917914ac Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Fri, 2 Jun 2023 13:01:58 +0200
Subject: [PATCH 06/12] Move parsing the event back to Dendrite

---
 federationapi/routing/leave.go | 30 +++++++++++++++++++++++++++---
 go.mod                         |  2 +-
 go.sum                         |  4 ++--
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/federationapi/routing/leave.go b/federationapi/routing/leave.go
index 49c7771246..636ade7489 100644
--- a/federationapi/routing/leave.go
+++ b/federationapi/routing/leave.go
@@ -165,8 +165,32 @@ func SendLeave(
 		}
 	}
 
-	event, err := gomatrixserverlib.HandleSendLeave(
-		httpReq.Context(), request.Content(), request.Origin(), roomVersion, eventID, roomID, rsAPI, keys,
+	verImpl, err := gomatrixserverlib.GetRoomVersion(roomVersion)
+	if err != nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: spec.UnsupportedRoomVersion(err.Error()),
+		}
+	}
+
+	// Decode the incomingEvent JSON from the request.
+	incomingEvent, err := verImpl.NewEventFromUntrustedJSON(request.Content())
+	switch err.(type) {
+	case gomatrixserverlib.BadJSONError:
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: spec.BadJSON(err.Error()),
+		}
+	case nil:
+	default:
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: spec.NotJSON("The request body could not be decoded into valid JSON. " + err.Error()),
+		}
+	}
+
+	leaveEvent, err := verImpl.HandleSendLeave(
+		httpReq.Context(), incomingEvent, request.Origin(), eventID, roomID, rsAPI, keys,
 	)
 
 	switch e := err.(type) {
@@ -211,7 +235,7 @@ func SendLeave(
 		InputRoomEvents: []api.InputRoomEvent{
 			{
 				Kind:          api.KindNew,
-				Event:         &types.HeaderedEvent{PDU: event},
+				Event:         &types.HeaderedEvent{PDU: leaveEvent},
 				SendAsServer:  string(cfg.Matrix.ServerName),
 				TransactionID: nil,
 			},
diff --git a/go.mod b/go.mod
index 8906b8c66b..d206c91ede 100644
--- a/go.mod
+++ b/go.mod
@@ -22,7 +22,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20230601112942-5d099f949e82
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20230602105922-540062a7516d
 	github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a
 	github.com/matrix-org/util v0.0.0-20221111132719-399730281e66
 	github.com/mattn/go-sqlite3 v1.14.16
diff --git a/go.sum b/go.sum
index 0060419f24..a551bc5a48 100644
--- a/go.sum
+++ b/go.sum
@@ -323,8 +323,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91 h1:s7fexw
 github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91/go.mod h1:e+cg2q7C7yE5QnAXgzo512tgFh1RbQLC0+jozuegKgo=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530 h1:kHKxCOLcHH8r4Fzarl4+Y3K5hjothkVW5z7T1dUM11U=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230601112942-5d099f949e82 h1:VC9MCGI47z3ksNQt/sTcnwO//syibxgyz/6ckD6BjkY=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230601112942-5d099f949e82/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230602105922-540062a7516d h1:7zP85gTIeoHb/GG0qRVi5uhwfnbSpt7G8SwDvGw7mUE=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230602105922-540062a7516d/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a h1:awrPDf9LEFySxTLKYBMCiObelNx/cBuv/wzllvCCH3A=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a/go.mod h1:HchJX9oKMXaT2xYFs0Ha/6Zs06mxLU8k6F1ODnrGkeQ=
 github.com/matrix-org/util v0.0.0-20221111132719-399730281e66 h1:6z4KxomXSIGWqhHcfzExgkH3Z3UkIXry4ibJS4Aqz2Y=

From e5d2b23ad0fe2f492a25bf176c26874b90c7d444 Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Thu, 23 Nov 2023 11:26:23 +0100
Subject: [PATCH 07/12] Revert changes

---
 federationapi/routing/leave.go | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/federationapi/routing/leave.go b/federationapi/routing/leave.go
index 636ade7489..57d75ad21b 100644
--- a/federationapi/routing/leave.go
+++ b/federationapi/routing/leave.go
@@ -189,9 +189,8 @@ func SendLeave(
 		}
 	}
 
-	leaveEvent, err := verImpl.HandleSendLeave(
-		httpReq.Context(), incomingEvent, request.Origin(), eventID, roomID, rsAPI, keys,
-	)
+	leaveEvent, err := gomatrixserverlib.HandleSendLeave(
+		httpReq.Context(), incomingEvent, request.Origin(), roomVersion, eventID, roomID, rsAPI, keys)
 
 	switch e := err.(type) {
 	case nil:

From af860fc6fa6987d7eeeeafba9f26085fc4f8aa02 Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Thu, 23 Nov 2023 12:21:01 +0100
Subject: [PATCH 08/12] Some tweaks

---
 federationapi/routing/leave.go | 37 +++++++++-------------------------
 1 file changed, 10 insertions(+), 27 deletions(-)

diff --git a/federationapi/routing/leave.go b/federationapi/routing/leave.go
index 5dc195f340..98a5810f00 100644
--- a/federationapi/routing/leave.go
+++ b/federationapi/routing/leave.go
@@ -184,34 +184,8 @@ func SendLeave(
 		}
 	}
 
-	verImpl, err := gomatrixserverlib.GetRoomVersion(roomVersion)
-	if err != nil {
-		return util.JSONResponse{
-			Code: http.StatusInternalServerError,
-			JSON: spec.UnsupportedRoomVersion(
-				fmt.Sprintf("QueryRoomVersionForRoom returned unknown version: %s", roomVersion),
-			),
-		}
-	}
-
-	// Decode the event JSON from the request.
-	event, err := verImpl.NewEventFromUntrustedJSON(request.Content())
-	switch err.(type) {
-	case gomatrixserverlib.BadJSONError:
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON(err.Error()),
-		}
-	case nil:
-	default:
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.NotJSON("The request body could not be decoded into valid JSON. " + err.Error()),
-		}
-	}
-
 	leaveEvent, err := gomatrixserverlib.HandleSendLeave(
-		httpReq.Context(), incomingEvent, request.Origin(), roomVersion, eventID, roomID, rsAPI, keys)
+		httpReq.Context(), request.Content(), request.Origin(), roomVersion, eventID, roomID, rsAPI, keys)
 
 	switch e := err.(type) {
 	case nil:
@@ -247,6 +221,15 @@ func SendLeave(
 		}
 	}
 
+	// The user was never joined to the room, has already left,
+	// or we already processed this leave event, so this is a no-op.
+	if leaveEvent == nil {
+		return util.JSONResponse{
+			Code: http.StatusOK,
+			JSON: struct{}{},
+		}
+	}
+
 	// Send the events to the room server.
 	// We are responsible for notifying other servers that the user has left
 	// the room, so set SendAsServer to cfg.Matrix.ServerName

From 57af9aede96b9b859f06423bdc201e605300add8 Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Thu, 23 Nov 2023 12:23:29 +0100
Subject: [PATCH 09/12] Update GMSL

---
 go.mod | 2 +-
 go.sum | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index a4bf8d341a..7b709a88e0 100644
--- a/go.mod
+++ b/go.mod
@@ -22,7 +22,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20230602105922-540062a7516d
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20231123112137-2369defc080e
 	github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7
 	github.com/matrix-org/util v0.0.0-20221111132719-399730281e66
 	github.com/mattn/go-sqlite3 v1.14.17
diff --git a/go.sum b/go.sum
index f188b3eebc..213a5f1662 100644
--- a/go.sum
+++ b/go.sum
@@ -208,8 +208,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91 h1:s7fexw
 github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91/go.mod h1:e+cg2q7C7yE5QnAXgzo512tgFh1RbQLC0+jozuegKgo=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530 h1:kHKxCOLcHH8r4Fzarl4+Y3K5hjothkVW5z7T1dUM11U=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230602105922-540062a7516d h1:7zP85gTIeoHb/GG0qRVi5uhwfnbSpt7G8SwDvGw7mUE=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230602105922-540062a7516d/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20231123112137-2369defc080e h1:+E3txSR4+DEo39eoTlVxo9lNXfjJ8f8iXsyYwr1Yugs=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20231123112137-2369defc080e/go.mod h1:M8m7seOroO5ePlgxA7AFZymnG90Cnh94rYQyngSrZkk=
 github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7 h1:6t8kJr8i1/1I5nNttw6nn1ryQJgzVlBmSGgPiiaTdw4=
 github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7/go.mod h1:ReWMS/LoVnOiRAdq9sNUC2NZnd1mZkMNB52QhpTRWjg=
 github.com/matrix-org/util v0.0.0-20221111132719-399730281e66 h1:6z4KxomXSIGWqhHcfzExgkH3Z3UkIXry4ibJS4Aqz2Y=

From 55a01df5c905dca2c0c32db14b82628bb43a79b0 Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Thu, 23 Nov 2023 12:51:50 +0100
Subject: [PATCH 10/12] Fix oopps

---
 federationapi/routing/leave.go | 23 +++++++++++++++++++++++
 go.mod                         |  2 +-
 go.sum                         |  4 ++--
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/federationapi/routing/leave.go b/federationapi/routing/leave.go
index 98a5810f00..c4b46af934 100644
--- a/federationapi/routing/leave.go
+++ b/federationapi/routing/leave.go
@@ -176,6 +176,29 @@ func SendLeave(
 	keys gomatrixserverlib.JSONVerifier,
 	roomID, eventID string,
 ) util.JSONResponse {
+	parsedRoomID, err := spec.NewRoomID(roomID)
+	if err != nil {
+		return util.JSONResponse{
+			Code: http.StatusInternalServerError,
+			JSON: spec.InternalServerError{},
+		}
+	}
+	roomInfo, err := rsAPI.QueryRoomInfo(httpReq.Context(), *parsedRoomID)
+	if err != nil {
+		return util.JSONResponse{
+			Code: http.StatusInternalServerError,
+			JSON: spec.InternalServerError{},
+		}
+	}
+	// Either the room does not exist or does not
+	// have any events.
+	if roomInfo == nil || roomInfo.IsStub() {
+		return util.JSONResponse{
+			Code: http.StatusOK,
+			JSON: struct{}{},
+		}
+	}
+
 	roomVersion, err := rsAPI.QueryRoomVersionForRoom(httpReq.Context(), roomID)
 	if err != nil {
 		return util.JSONResponse{
diff --git a/go.mod b/go.mod
index 7b709a88e0..709e679b81 100644
--- a/go.mod
+++ b/go.mod
@@ -22,7 +22,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20231123112137-2369defc080e
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20231123113708-498c48650dc9
 	github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7
 	github.com/matrix-org/util v0.0.0-20221111132719-399730281e66
 	github.com/mattn/go-sqlite3 v1.14.17
diff --git a/go.sum b/go.sum
index 213a5f1662..13960a7962 100644
--- a/go.sum
+++ b/go.sum
@@ -208,8 +208,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91 h1:s7fexw
 github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91/go.mod h1:e+cg2q7C7yE5QnAXgzo512tgFh1RbQLC0+jozuegKgo=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530 h1:kHKxCOLcHH8r4Fzarl4+Y3K5hjothkVW5z7T1dUM11U=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20231123112137-2369defc080e h1:+E3txSR4+DEo39eoTlVxo9lNXfjJ8f8iXsyYwr1Yugs=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20231123112137-2369defc080e/go.mod h1:M8m7seOroO5ePlgxA7AFZymnG90Cnh94rYQyngSrZkk=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20231123113708-498c48650dc9 h1:jf2D3nqdpb/AWyKPeNScYMphaf0FnmoqdulKmTz8484=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20231123113708-498c48650dc9/go.mod h1:M8m7seOroO5ePlgxA7AFZymnG90Cnh94rYQyngSrZkk=
 github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7 h1:6t8kJr8i1/1I5nNttw6nn1ryQJgzVlBmSGgPiiaTdw4=
 github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7/go.mod h1:ReWMS/LoVnOiRAdq9sNUC2NZnd1mZkMNB52QhpTRWjg=
 github.com/matrix-org/util v0.0.0-20221111132719-399730281e66 h1:6z4KxomXSIGWqhHcfzExgkH3Z3UkIXry4ibJS4Aqz2Y=

From f4e8ed6f1f287bd409bd88506092da696dfdf069 Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Thu, 23 Nov 2023 13:02:03 +0100
Subject: [PATCH 11/12] No need to get the roomVersion twice

---
 federationapi/routing/leave.go | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/federationapi/routing/leave.go b/federationapi/routing/leave.go
index c4b46af934..2612f61013 100644
--- a/federationapi/routing/leave.go
+++ b/federationapi/routing/leave.go
@@ -199,16 +199,8 @@ func SendLeave(
 		}
 	}
 
-	roomVersion, err := rsAPI.QueryRoomVersionForRoom(httpReq.Context(), roomID)
-	if err != nil {
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.UnsupportedRoomVersion(err.Error()),
-		}
-	}
-
 	leaveEvent, err := gomatrixserverlib.HandleSendLeave(
-		httpReq.Context(), request.Content(), request.Origin(), roomVersion, eventID, roomID, rsAPI, keys)
+		httpReq.Context(), request.Content(), request.Origin(), roomInfo.RoomVersion, eventID, roomID, rsAPI, keys)
 
 	switch e := err.(type) {
 	case nil:

From 86ad6c64f5f63e3b50790af0b386c0578ee7707c Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Thu, 23 Nov 2023 14:34:26 +0100
Subject: [PATCH 12/12] Update GMSL a last time

---
 go.mod | 2 +-
 go.sum | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index 709e679b81..fc666f9a2a 100644
--- a/go.mod
+++ b/go.mod
@@ -22,7 +22,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20231123113708-498c48650dc9
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20231123125815-185a49a8c72d
 	github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7
 	github.com/matrix-org/util v0.0.0-20221111132719-399730281e66
 	github.com/mattn/go-sqlite3 v1.14.17
diff --git a/go.sum b/go.sum
index 13960a7962..4d2aea84ce 100644
--- a/go.sum
+++ b/go.sum
@@ -208,8 +208,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91 h1:s7fexw
 github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91/go.mod h1:e+cg2q7C7yE5QnAXgzo512tgFh1RbQLC0+jozuegKgo=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530 h1:kHKxCOLcHH8r4Fzarl4+Y3K5hjothkVW5z7T1dUM11U=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20231123113708-498c48650dc9 h1:jf2D3nqdpb/AWyKPeNScYMphaf0FnmoqdulKmTz8484=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20231123113708-498c48650dc9/go.mod h1:M8m7seOroO5ePlgxA7AFZymnG90Cnh94rYQyngSrZkk=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20231123125815-185a49a8c72d h1:gdXFfDL6daF/mf6PihcArRITjbT5HJGApkaHR9Z3KWs=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20231123125815-185a49a8c72d/go.mod h1:M8m7seOroO5ePlgxA7AFZymnG90Cnh94rYQyngSrZkk=
 github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7 h1:6t8kJr8i1/1I5nNttw6nn1ryQJgzVlBmSGgPiiaTdw4=
 github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7/go.mod h1:ReWMS/LoVnOiRAdq9sNUC2NZnd1mZkMNB52QhpTRWjg=
 github.com/matrix-org/util v0.0.0-20221111132719-399730281e66 h1:6z4KxomXSIGWqhHcfzExgkH3Z3UkIXry4ibJS4Aqz2Y=