Return state on calls to /message and lazy load members (#2218)

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>

3 files changed, 41 insertions, 30 deletions

diff --git a/syncapi/routing/context.go b/syncapi/routing/context.go
index ef7efa2b..59113971 100644
--- a/syncapi/routing/context.go
+++ b/syncapi/routing/context.go
@@ -44,7 +44,7 @@ func Context(
 	syncDB storage.Database,
 	roomID, eventID string,
 ) util.JSONResponse {
-	filter, err := parseContextParams(req)
+	filter, err := parseRoomEventFilter(req)
 	if err != nil {
 		errMsg := ""
 		switch err.(type) {
@@ -164,7 +164,7 @@ func applyLazyLoadMembers(filter *gomatrixserverlib.RoomEventFilter, eventsAfter
 	return newState
 }
 
-func parseContextParams(req *http.Request) (*gomatrixserverlib.RoomEventFilter, error) {
+func parseRoomEventFilter(req *http.Request) (*gomatrixserverlib.RoomEventFilter, error) {
 	// Default room filter
 	filter := &gomatrixserverlib.RoomEventFilter{Limit: 10}
 
diff --git a/syncapi/routing/context_test.go b/syncapi/routing/context_test.go
index 1b430d83..e79a5d5f 100644
--- a/syncapi/routing/context_test.go
+++ b/syncapi/routing/context_test.go
@@ -55,13 +55,13 @@ func Test_parseContextParams(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			gotFilter, err := parseContextParams(tt.req)
+			gotFilter, err := parseRoomEventFilter(tt.req)
 			if (err != nil) != tt.wantErr {
-				t.Errorf("parseContextParams() error = %v, wantErr %v", err, tt.wantErr)
+				t.Errorf("parseRoomEventFilter() error = %v, wantErr %v", err, tt.wantErr)
 				return
 			}
 			if !reflect.DeepEqual(gotFilter, tt.wantFilter) {
-				t.Errorf("parseContextParams() gotFilter = %v, want %v", gotFilter, tt.wantFilter)
+				t.Errorf("parseRoomEventFilter() gotFilter = %v, want %v", gotFilter, tt.wantFilter)
 			}
 		})
 	}
diff --git a/syncapi/routing/messages.go b/syncapi/routing/messages.go
index 9bb8c6d2..7cd54eef 100644
--- a/syncapi/routing/messages.go
+++ b/syncapi/routing/messages.go
@@ -19,7 +19,6 @@ import (
 	"fmt"
 	"net/http"
 	"sort"
-	"strconv"
 
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
 	"github.com/matrix-org/dendrite/roomserver/api"
@@ -45,8 +44,8 @@ type messagesReq struct {
 	fromStream       *types.StreamingToken
 	device           *userapi.Device
 	wasToProvided    bool
-	limit            int
 	backwardOrdering bool
+	filter           *gomatrixserverlib.RoomEventFilter
 }
 
 type messagesResp struct {
@@ -54,10 +53,9 @@ type messagesResp struct {
 	StartStream string                          `json:"start_stream,omitempty"` // NOTSPEC: so clients can hit /messages then immediately /sync with a latest sync token
 	End         string                          `json:"end"`
 	Chunk       []gomatrixserverlib.ClientEvent `json:"chunk"`
+	State       []gomatrixserverlib.ClientEvent `json:"state"`
 }
 
-const defaultMessagesLimit = 10
-
 // OnIncomingMessagesRequest implements the /messages endpoint from the
 // client-server API.
 // See: https://matrix.org/docs/spec/client_server/latest.html#get-matrix-client-r0-rooms-roomid-messages
@@ -83,6 +81,14 @@ func OnIncomingMessagesRequest(
 		}
 	}
 
+	filter, err := parseRoomEventFilter(req)
+	if err != nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.InvalidArgumentValue("unable to parse filter"),
+		}
+	}
+
 	// Extract parameters from the request's URL.
 	// Pagination tokens.
 	var fromStream *types.StreamingToken
@@ -143,18 +149,6 @@ func OnIncomingMessagesRequest(
 		wasToProvided = false
 	}
 
-	// Maximum number of events to return; defaults to 10.
-	limit := defaultMessagesLimit
-	if len(req.URL.Query().Get("limit")) > 0 {
-		limit, err = strconv.Atoi(req.URL.Query().Get("limit"))
-
-		if err != nil {
-			return util.JSONResponse{
-				Code: http.StatusBadRequest,
-				JSON: jsonerror.InvalidArgumentValue("limit could not be parsed into an integer: " + err.Error()),
-			}
-		}
-	}
 	// TODO: Implement filtering (#587)
 
 	// Check the room ID's format.
@@ -176,7 +170,7 @@ func OnIncomingMessagesRequest(
 		to:               &to,
 		fromStream:       fromStream,
 		wasToProvided:    wasToProvided,
-		limit:            limit,
+		filter:           filter,
 		backwardOrdering: backwardOrdering,
 		device:           device,
 	}
@@ -187,10 +181,27 @@ func OnIncomingMessagesRequest(
 		return jsonerror.InternalServerError()
 	}
 
+	// at least fetch the membership events for the users returned in chunk if LazyLoadMembers is set
+	state := []gomatrixserverlib.ClientEvent{}
+	if filter.LazyLoadMembers {
+		memberShipToUser := make(map[string]*gomatrixserverlib.HeaderedEvent)
+		for _, evt := range clientEvents {
+			memberShip, err := db.GetStateEvent(req.Context(), roomID, gomatrixserverlib.MRoomMember, evt.Sender)
+			if err != nil {
+				util.GetLogger(req.Context()).WithError(err).Error("failed to get membership event for user")
+				continue
+			}
+			memberShipToUser[evt.Sender] = memberShip
+		}
+		for _, evt := range memberShipToUser {
+			state = append(state, gomatrixserverlib.HeaderedToClientEvent(evt, gomatrixserverlib.FormatAll))
+		}
+	}
+
 	util.GetLogger(req.Context()).WithFields(logrus.Fields{
 		"from":         from.String(),
 		"to":           to.String(),
-		"limit":        limit,
+		"limit":        filter.Limit,
 		"backwards":    backwardOrdering,
 		"return_start": start.String(),
 		"return_end":   end.String(),
@@ -200,6 +211,7 @@ func OnIncomingMessagesRequest(
 		Chunk: clientEvents,
 		Start: start.String(),
 		End:   end.String(),
+		State: state,
 	}
 	if emptyFromSupplied {
 		res.StartStream = fromStream.String()
@@ -234,19 +246,18 @@ func (r *messagesReq) retrieveEvents() (
 	clientEvents []gomatrixserverlib.ClientEvent, start,
 	end types.TopologyToken, err error,
 ) {
-	eventFilter := gomatrixserverlib.DefaultRoomEventFilter()
-	eventFilter.Limit = r.limit
+	eventFilter := r.filter
 
 	// Retrieve the events from the local database.
 	var streamEvents []types.StreamEvent
 	if r.fromStream != nil {
 		toStream := r.to.StreamToken()
 		streamEvents, err = r.db.GetEventsInStreamingRange(
-			r.ctx, r.fromStream, &toStream, r.roomID, &eventFilter, r.backwardOrdering,
+			r.ctx, r.fromStream, &toStream, r.roomID, eventFilter, r.backwardOrdering,
 		)
 	} else {
 		streamEvents, err = r.db.GetEventsInTopologicalRange(
-			r.ctx, r.from, r.to, r.roomID, r.limit, r.backwardOrdering,
+			r.ctx, r.from, r.to, r.roomID, eventFilter.Limit, r.backwardOrdering,
 		)
 	}
 	if err != nil {
@@ -434,7 +445,7 @@ func (r *messagesReq) handleEmptyEventsSlice() (
 	// Check if we have backward extremities for this room.
 	if len(backwardExtremities) > 0 {
 		// If so, retrieve as much events as needed through backfilling.
-		events, err = r.backfill(r.roomID, backwardExtremities, r.limit)
+		events, err = r.backfill(r.roomID, backwardExtremities, r.filter.Limit)
 		if err != nil {
 			return
 		}
@@ -456,7 +467,7 @@ func (r *messagesReq) handleNonEmptyEventsSlice(streamEvents []types.StreamEvent
 	events []*gomatrixserverlib.HeaderedEvent, err error,
 ) {
 	// Check if we have enough events.
-	isSetLargeEnough := len(streamEvents) >= r.limit
+	isSetLargeEnough := len(streamEvents) >= r.filter.Limit
 	if !isSetLargeEnough {
 		// it might be fine we don't have up to 'limit' events, let's find out
 		if r.backwardOrdering {
@@ -483,7 +494,7 @@ func (r *messagesReq) handleNonEmptyEventsSlice(streamEvents []types.StreamEvent
 	if len(backwardExtremities) > 0 && !isSetLargeEnough && r.backwardOrdering {
 		var pdus []*gomatrixserverlib.HeaderedEvent
 		// Only ask the remote server for enough events to reach the limit.
-		pdus, err = r.backfill(r.roomID, backwardExtremities, r.limit-len(streamEvents))
+		pdus, err = r.backfill(r.roomID, backwardExtremities, r.filter.Limit-len(streamEvents))
 		if err != nil {
 			return
 		}