use go module for dependencies (#594)

federationapi/routing/missingevents.go

@@ -0,0 +1,80 @@
+// 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"
+	"net/http"
+
+	"github.com/matrix-org/dendrite/clientapi/httputil"
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+type getMissingEventRequest struct {
+	EarliestEvents []string `json:"earliest_events"`
+	LatestEvents   []string `json:"latest_events"`
+	Limit          int      `json:"limit"`
+	MinDepth       int64    `json:"min_depth"`
+}
+
+// GetMissingEvents returns missing events between earliest_events & latest_events.
+// Events are fetched from room DAG starting from latest_events until we reach earliest_events or the limit.
+func GetMissingEvents(
+	httpReq *http.Request,
+	request *gomatrixserverlib.FederationRequest,
+	query api.RoomserverQueryAPI,
+	roomID string,
+) util.JSONResponse {
+	var gme getMissingEventRequest
+	if err := json.Unmarshal(request.Content(), &gme); err != nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.NotJSON("The request body could not be decoded into valid JSON. " + err.Error()),
+		}
+	}
+
+	var eventsResponse api.QueryMissingEventsResponse
+	if err := query.QueryMissingEvents(
+		httpReq.Context(), &api.QueryMissingEventsRequest{
+			EarliestEvents: gme.EarliestEvents,
+			LatestEvents:   gme.LatestEvents,
+			Limit:          gme.Limit,
+			ServerName:     request.Origin(),
+		},
+		&eventsResponse,
+	); err != nil {
+		return httputil.LogThenError(httpReq, err)
+	}
+
+	eventsResponse.Events = filterEvents(eventsResponse.Events, gme.MinDepth, roomID)
+	return util.JSONResponse{
+		Code: http.StatusOK,
+		JSON: eventsResponse,
+	}
+}
+
+// filterEvents returns only those events with matching roomID and having depth greater than minDepth
+func filterEvents(
+	events []gomatrixserverlib.Event, minDepth int64, roomID string,
+) []gomatrixserverlib.Event {
+	ref := events[:0]
+	for _, ev := range events {
+		if ev.Depth() >= minDepth && ev.RoomID() == roomID {
+			ref = append(ref, ev)
+		}
+	}
+	return ref
+}