Fix cases for world-readable history visibility

clientapi/routing/state.go

@@ -17,6 +17,7 @@ package routing
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"net/http"
 
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
@@ -100,58 +101,123 @@ func OnIncomingStateRequest(ctx context.Context, rsAPI api.RoomserverInternalAPI
 // state to see if there is an event with that type and state key, if there
 // is then (by default) we return the content, otherwise a 404.
 // If eventFormat=true, sends the whole event else just the content.
+// nolint:gocyclo
 func OnIncomingStateTypeRequest(
 	ctx context.Context, device *userapi.Device, rsAPI api.RoomserverInternalAPI,
 	roomID, evType, stateKey string, eventFormat bool,
 ) util.JSONResponse {
-	// TODO(#287): Auth request and handle the case where the user has left (where
-	// we should return the state at the poin they left)
+	var worldReadable bool
+	var wantLatestState bool
 
-	var membershipRes api.QueryMembershipForUserResponse
-	err := rsAPI.QueryMembershipForUser(ctx, &api.QueryMembershipForUserRequest{
-		RoomID: roomID,
-		UserID: device.UserID,
-	}, &membershipRes)
-	if err != nil {
-		util.GetLogger(ctx).WithError(err).Error("Failed to QueryMembershipForUser")
+	// Always fetch visibility so that we can work out whether to show
+	// the latest events or the last event from when the user was joined.
+	// Then include the requested event type and state key, assuming it
+	// isn't for the same.
+	toFetch := []gomatrixserverlib.StateKeyTuple{
+		{
+			EventType: gomatrixserverlib.MRoomHistoryVisibility,
+			StateKey:  "",
+		},
+	}
+	if evType != gomatrixserverlib.MRoomHistoryVisibility && stateKey != "" {
+		toFetch = append(toFetch, gomatrixserverlib.StateKeyTuple{
+			EventType: evType,
+			StateKey:  stateKey,
+		})
+	}
+
+	// First of all, get the latest state of the room. We need to do this
+	// so that we can look at the history visibility of the room. If the
+	// room is world-readable then we will always return the latest state.
+	stateRes := api.QueryLatestEventsAndStateResponse{}
+	if err := rsAPI.QueryLatestEventsAndState(ctx, &api.QueryLatestEventsAndStateRequest{
+		RoomID:       roomID,
+		StateToFetch: toFetch,
+	}, &stateRes); err != nil {
+		util.GetLogger(ctx).WithError(err).Error("queryAPI.QueryLatestEventsAndState failed")
 		return jsonerror.InternalServerError()
 	}
-	if !membershipRes.HasBeenInRoom {
-		return util.JSONResponse{
-			Code: http.StatusForbidden,
-			JSON: jsonerror.Forbidden("Unknown room or user is not in room"),
+
+	// Look at the room state and see if we have a history visibility event
+	// that marks the room as world-readable. If we don't then we assume that
+	// the room is not world-readable.
+	for i, ev := range stateRes.StateEvents {
+		if ev.Type() == gomatrixserverlib.MRoomHistoryVisibility {
+			content := map[string]string{}
+			if err := json.Unmarshal(ev.Content(), &content); err != nil {
+				util.GetLogger(ctx).WithError(err).Error("json.Unmarshal for history visibility failed")
+				return jsonerror.InternalServerError()
+			}
+			if visibility, ok := content["history_visibility"]; ok {
+				worldReadable = visibility == "world_readable"
+				// If the request is for the history visibility of the room
+				// specifically then keep it in the response, otherwise discard
+				// it so that the later checks make sense.
+				if evType != gomatrixserverlib.MRoomHistoryVisibility && stateKey != "" {
+					stateRes.StateEvents = append(stateRes.StateEvents[:i], stateRes.StateEvents[i+1:]...)
+				}
+				break
+			}
 		}
 	}
 
+	// If the room isn't world-readable then we will instead try to find out
+	// the state of the room based on the user's membership. If the user is
+	// in the room then we'll want the latest state. If the user has never
+	// been in the room and the room isn't world-readable, then we won't
+	// return any state. If the user was in the room previously but is no
+	// longer then we will return the state at the time that the user left.
+	// membershipRes will only be populated if the room is not world-readable.
+	var membershipRes api.QueryMembershipForUserResponse
+	if !worldReadable {
+		// The room isn't world-readable so try to work out based on the
+		// user's membership if we want the latest state or not.
+		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 {
+			return util.JSONResponse{
+				Code: http.StatusForbidden,
+				JSON: jsonerror.Forbidden(fmt.Sprintf("Unknown room %q or user %q has never joined this room", roomID, device.UserID)),
+			}
+		}
+		// Otherwise, if the user has been in the room, whether or not we
+		// give them the latest state will depend on if they are *still* in
+		// the room.
+		wantLatestState = membershipRes.IsInRoom
+	} else {
+		// The room is world-readable so the user join state is irrelevant,
+		// just get the latest room state instead.
+		wantLatestState = true
+	}
+
 	util.GetLogger(ctx).WithFields(log.Fields{
 		"roomID":         roomID,
 		"evType":         evType,
 		"stateKey":       stateKey,
-		"state_at_event": !membershipRes.IsInRoom,
+		"state_at_event": !wantLatestState,
 	}).Info("Fetching state")
 
 	var event *gomatrixserverlib.HeaderedEvent
-	if membershipRes.IsInRoom {
-		stateRes := api.QueryLatestEventsAndStateResponse{}
-		if err = rsAPI.QueryLatestEventsAndState(ctx, &api.QueryLatestEventsAndStateRequest{
-			RoomID: roomID,
-			StateToFetch: []gomatrixserverlib.StateKeyTuple{
-				gomatrixserverlib.StateKeyTuple{
-					EventType: evType,
-					StateKey:  stateKey,
-				},
-			},
-		}, &stateRes); err != nil {
-			util.GetLogger(ctx).WithError(err).Error("queryAPI.QueryLatestEventsAndState failed")
-			return jsonerror.InternalServerError()
-		}
+	if wantLatestState {
+		// If we are happy to use the latest state, either because the user is
+		// still in the room, or because the room is world-readable, then just
+		// use the result of the previous QueryLatestEventsAndState response.
 		if len(stateRes.StateEvents) > 0 {
 			event = &stateRes.StateEvents[0]
 		}
 	} else {
-		// fetch the state at the time they left
+		// Otherwise, take the event ID of their leave event and work out what
+		// the state of the room was before that event.
 		var stateAfterRes api.QueryStateAfterEventsResponse
-		err = rsAPI.QueryStateAfterEvents(ctx, &api.QueryStateAfterEventsRequest{
+		err := rsAPI.QueryStateAfterEvents(ctx, &api.QueryStateAfterEventsRequest{
 			RoomID:       roomID,
 			PrevEventIDs: []string{membershipRes.EventID},
 			StateToFetch: []gomatrixserverlib.StateKeyTuple{
@@ -170,10 +236,12 @@ func OnIncomingStateTypeRequest(
 		}
 	}
 
+	// If there was no event found that matches all of the above criteria then
+	// return an error.
 	if event == nil {
 		return util.JSONResponse{
 			Code: http.StatusNotFound,
-			JSON: jsonerror.NotFound("cannot find state"),
+			JSON: jsonerror.NotFound(fmt.Sprintf("Cannot find state event for %q", evType)),
 		}
 	}
 

sytest-whitelist

@@ -415,3 +415,4 @@ We don't send redundant membership state across incremental syncs by default
 Typing notifications don't leak
 Users cannot kick users from a room they are not in
 Users cannot kick users who have already left a room
+Can get 'm.room.name' state for a departed room (SPEC-216)