Various alias fixes (#1934)

* Generate m.room.canonical_alias instead of legacy m.room.aliases

* Add omitempty tags

* Add aliases endpoint to client API

* Check power levels when setting aliases

* Don't return null on /aliases

* Don't return error if the state event fails

* Update sytest-whitelist

* Don't send updated m.room.canonical_alias events

* Don't check PLs after all because for local aliases they are apparently irrelevant

* Fix some bugs

* Allow deleting a local alias with enough PL

* Fix some more bugs

* Update sytest-whitelist

* Fix copyright notices

* Review comments

clientapi/routing/aliases.go

@@ -0,0 +1,96 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package routing
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	userapi "github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/gomatrixserverlib"
+
+	"github.com/matrix-org/util"
+)
+
+// GetAliases implements GET /_matrix/client/r0/rooms/{roomId}/aliases
+func GetAliases(
+	req *http.Request, rsAPI api.RoomserverInternalAPI, device *userapi.Device, roomID string,
+) util.JSONResponse {
+	stateTuple := gomatrixserverlib.StateKeyTuple{
+		EventType: gomatrixserverlib.MRoomHistoryVisibility,
+		StateKey:  "",
+	}
+	stateReq := &api.QueryCurrentStateRequest{
+		RoomID:      roomID,
+		StateTuples: []gomatrixserverlib.StateKeyTuple{stateTuple},
+	}
+	stateRes := &api.QueryCurrentStateResponse{}
+	if err := rsAPI.QueryCurrentState(req.Context(), stateReq, stateRes); err != nil {
+		util.GetLogger(req.Context()).WithError(err).Error("rsAPI.QueryCurrentState failed")
+		return util.ErrorResponse(fmt.Errorf("rsAPI.QueryCurrentState: %w", err))
+	}
+
+	visibility := "invite"
+	if historyVisEvent, ok := stateRes.StateEvents[stateTuple]; ok {
+		var err error
+		visibility, err = historyVisEvent.HistoryVisibility()
+		if err != nil {
+			util.GetLogger(req.Context()).WithError(err).Error("historyVisEvent.HistoryVisibility failed")
+			return util.ErrorResponse(fmt.Errorf("historyVisEvent.HistoryVisibility: %w", err))
+		}
+	}
+	if visibility != gomatrixserverlib.WorldReadable {
+		queryReq := api.QueryMembershipForUserRequest{
+			RoomID: roomID,
+			UserID: device.UserID,
+		}
+		var queryRes api.QueryMembershipForUserResponse
+		if err := rsAPI.QueryMembershipForUser(req.Context(), &queryReq, &queryRes); err != nil {
+			util.GetLogger(req.Context()).WithError(err).Error("rsAPI.QueryMembershipsForRoom failed")
+			return jsonerror.InternalServerError()
+		}
+		if !queryRes.IsInRoom {
+			return util.JSONResponse{
+				Code: http.StatusForbidden,
+				JSON: jsonerror.Forbidden("You aren't a member of this room."),
+			}
+		}
+	}
+
+	aliasesReq := api.GetAliasesForRoomIDRequest{
+		RoomID: roomID,
+	}
+	aliasesRes := api.GetAliasesForRoomIDResponse{}
+	if err := rsAPI.GetAliasesForRoomID(req.Context(), &aliasesReq, &aliasesRes); err != nil {
+		util.GetLogger(req.Context()).WithError(err).Error("rsAPI.GetAliasesForRoomID failed")
+		return util.ErrorResponse(fmt.Errorf("rsAPI.GetAliasesForRoomID: %w", err))
+	}
+
+	response := struct {
+		Aliases []string `json:"aliases"`
+	}{
+		Aliases: aliasesRes.Aliases,
+	}
+	if response.Aliases == nil {
+		response.Aliases = []string{} // pleases sytest
+	}
+
+	return util.JSONResponse{
+		Code: 200,
+		JSON: response,
+	}
+}