Implement /sync limited and read timeline limit from stored filters (#1168)

* Move filter table to syncapi where it is used

* Implement /sync `limited` and read timeline limit from stored filters

We now fully handle `room.timeline.limit` filters (in-line + stored) and
return the right value for `limited` syncs.

* Update whitelist

* Default to the default timeline limit if it's unset, also strip the extra event correctly

* Update whitelist

syncapi/routing/filter.go

@@ -0,0 +1,128 @@
+// Copyright 2017 Jan Christian Grünhage
+//
+// 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 (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/syncapi/storage"
+	"github.com/matrix-org/dendrite/syncapi/sync"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+	"github.com/tidwall/gjson"
+)
+
+// GetFilter implements GET /_matrix/client/r0/user/{userId}/filter/{filterId}
+func GetFilter(
+	req *http.Request, device *api.Device, syncDB storage.Database, userID string, filterID string,
+) util.JSONResponse {
+	if userID != device.UserID {
+		return util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden("Cannot get filters for other users"),
+		}
+	}
+	localpart, _, err := gomatrixserverlib.SplitID('@', userID)
+	if err != nil {
+		util.GetLogger(req.Context()).WithError(err).Error("gomatrixserverlib.SplitID failed")
+		return jsonerror.InternalServerError()
+	}
+
+	filter, err := syncDB.GetFilter(req.Context(), localpart, filterID)
+	if err != nil {
+		//TODO better error handling. This error message is *probably* right,
+		// but if there are obscure db errors, this will also be returned,
+		// even though it is not correct.
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.NotFound("No such filter"),
+		}
+	}
+
+	return util.JSONResponse{
+		Code: http.StatusOK,
+		JSON: filter,
+	}
+}
+
+type filterResponse struct {
+	FilterID string `json:"filter_id"`
+}
+
+//PutFilter implements POST /_matrix/client/r0/user/{userId}/filter
+func PutFilter(
+	req *http.Request, device *api.Device, syncDB storage.Database, userID string,
+) util.JSONResponse {
+	if userID != device.UserID {
+		return util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden("Cannot create filters for other users"),
+		}
+	}
+
+	localpart, _, err := gomatrixserverlib.SplitID('@', userID)
+	if err != nil {
+		util.GetLogger(req.Context()).WithError(err).Error("gomatrixserverlib.SplitID failed")
+		return jsonerror.InternalServerError()
+	}
+
+	var filter gomatrixserverlib.Filter
+
+	defer req.Body.Close() // nolint:errcheck
+	body, err := ioutil.ReadAll(req.Body)
+	if err != nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("The request body could not be read. " + err.Error()),
+		}
+	}
+
+	if err = json.Unmarshal(body, &filter); err != nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("The request body could not be decoded into valid JSON. " + err.Error()),
+		}
+	}
+	// the filter `limit` is `int` which defaults to 0 if not set which is not what we want. We want to use the default
+	// limit if it is unset, which is what this does.
+	limitRes := gjson.GetBytes(body, "room.timeline.limit")
+	if !limitRes.Exists() {
+		util.GetLogger(req.Context()).Infof("missing timeline limit, using default")
+		filter.Room.Timeline.Limit = sync.DefaultTimelineLimit
+	}
+
+	// Validate generates a user-friendly error
+	if err = filter.Validate(); err != nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("Invalid filter: " + err.Error()),
+		}
+	}
+
+	filterID, err := syncDB.PutFilter(req.Context(), localpart, &filter)
+	if err != nil {
+		util.GetLogger(req.Context()).WithError(err).Error("syncDB.PutFilter failed")
+		return jsonerror.InternalServerError()
+	}
+
+	return util.JSONResponse{
+		Code: http.StatusOK,
+		JSON: filterResponse{FilterID: filterID},
+	}
+}