Implement GET /rooms/{roomID}/state/{type}/{stateKey} (#276)

* Implement GET /rooms/{roomID}/state/{type}/{stateKey}

* Add comments

src/github.com/matrix-org/dendrite/syncapi/routing/routing.go

@@ -39,4 +39,14 @@ func Setup(apiMux *mux.Router, srp *sync.RequestPool, deviceDB *devices.Database
 		vars := mux.Vars(req)
 		return srp.OnIncomingStateRequest(req, vars["roomID"])
 	})).Methods("GET")
+
+	r0mux.Handle("/rooms/{roomID}/state/{type}", common.MakeAuthAPI("room_state", deviceDB, func(req *http.Request, device *authtypes.Device) util.JSONResponse {
+		vars := mux.Vars(req)
+		return srp.OnIncomingStateTypeRequest(req, vars["roomID"], vars["type"], "")
+	})).Methods("GET")
+
+	r0mux.Handle("/rooms/{roomID}/state/{type}/{stateKey}", common.MakeAuthAPI("room_state", deviceDB, func(req *http.Request, device *authtypes.Device) util.JSONResponse {
+		vars := mux.Vars(req)
+		return srp.OnIncomingStateTypeRequest(req, vars["roomID"], vars["type"], vars["stateKey"])
+	})).Methods("GET")
 }

src/github.com/matrix-org/dendrite/syncapi/storage/current_room_state_table.go

@@ -70,7 +70,7 @@ const selectJoinedUsersSQL = "" +
 	"SELECT room_id, state_key FROM syncapi_current_room_state WHERE type = 'm.room.member' AND membership = 'join'"
 
 const selectStateEventSQL = "" +
-	"SELECT event_json FROM syncapi_current_room_state WHERE type = $1 AND room_id = $2 AND state_key = $3"
+	"SELECT event_json FROM syncapi_current_room_state WHERE room_id = $1 AND type = $2 AND state_key = $3"
 
 const selectEventsWithEventIDsSQL = "" +
 	"SELECT added_at, event_json FROM syncapi_current_room_state WHERE event_id = ANY($1)"
@@ -233,11 +233,11 @@ func rowsToEvents(rows *sql.Rows) ([]gomatrixserverlib.Event, error) {
 }
 
 func (s *currentRoomStateStatements) selectStateEvent(
-	ctx context.Context, evType string, roomID string, stateKey string,
+	ctx context.Context, roomID, evType, stateKey string,
 ) (*gomatrixserverlib.Event, error) {
 	stmt := s.selectStateEventStmt
 	var res []byte
-	err := stmt.QueryRowContext(ctx, evType, roomID, stateKey).Scan(&res)
+	err := stmt.QueryRowContext(ctx, roomID, evType, stateKey).Scan(&res)
 	if err == sql.ErrNoRows {
 		return nil, nil
 	}

src/github.com/matrix-org/dendrite/syncapi/storage/syncserver.go

@@ -157,9 +157,9 @@ func (d *SyncServerDatabase) updateRoomState(
 // If no event could be found, returns nil
 // If there was an issue during the retrieval, returns an error
 func (d *SyncServerDatabase) GetStateEvent(
-	ctx context.Context, evType, roomID, stateKey string,
+	ctx context.Context, roomID, evType, stateKey string,
 ) (*gomatrixserverlib.Event, error) {
-	return d.roomstate.selectStateEvent(ctx, evType, roomID, stateKey)
+	return d.roomstate.selectStateEvent(ctx, roomID, evType, stateKey)
 }
 
 // GetStateEventsForRoom fetches the state events for a given room.

src/github.com/matrix-org/dendrite/syncapi/sync/requestpool.go

@@ -120,6 +120,9 @@ type stateEventInStateResp struct {
 // is publicly visible. Current behaviour is returning an empty array if the
 // user cannot see the room's history.
 func (rp *RequestPool) OnIncomingStateRequest(req *http.Request, roomID string) 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)
+
 	stateEvents, err := rp.db.GetStateEventsForRoom(req.Context(), roomID)
 	if err != nil {
 		return httputil.LogThenError(req, err)
@@ -156,6 +159,43 @@ func (rp *RequestPool) OnIncomingStateRequest(req *http.Request, roomID string)
 	}
 }
 
+// OnIncomingStateTypeRequest is called when a client makes a
+// /rooms/{roomID}/state/{type}/{statekey} request. It will look in current
+// 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.
+func (rp *RequestPool) OnIncomingStateTypeRequest(req *http.Request, roomID string, evType, stateKey string) 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)
+
+	logger := util.GetLogger(req.Context())
+	logger.WithFields(log.Fields{
+		"roomID":   roomID,
+		"evType":   evType,
+		"stateKey": stateKey,
+	}).Info("Fetching state")
+
+	event, err := rp.db.GetStateEvent(req.Context(), roomID, evType, stateKey)
+	if err != nil {
+		return httputil.LogThenError(req, err)
+	}
+
+	if event == nil {
+		return util.JSONResponse{
+			Code: 404,
+			JSON: jsonerror.NotFound("cannot find state"),
+		}
+	}
+
+	stateEvent := stateEventInStateResp{
+		ClientEvent: gomatrixserverlib.ToClientEvent(*event, gomatrixserverlib.FormatAll),
+	}
+
+	return util.JSONResponse{
+		Code: 200,
+		JSON: stateEvent.Content,
+	}
+}
+
 func (rp *RequestPool) currentSyncForUser(req syncRequest, currentPos types.StreamPosition) (*types.Response, error) {
 	// TODO: handle ignored users
 	if req.since == types.StreamPosition(0) {