use go module for dependencies (#594)

federationapi/routing/events.go

@@ -0,0 +1,84 @@
+// Copyright 2017 New Vector Ltd
+//
+// 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 (
+	"context"
+	"net/http"
+
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+// GetEvent returns the requested event
+func GetEvent(
+	ctx context.Context,
+	request *gomatrixserverlib.FederationRequest,
+	query api.RoomserverQueryAPI,
+	eventID string,
+) util.JSONResponse {
+	event, err := getEvent(ctx, request, query, eventID)
+	if err != nil {
+		return *err
+	}
+
+	return util.JSONResponse{Code: http.StatusOK, JSON: event}
+}
+
+// getEvent returns the requested event,
+// otherwise it returns an error response which can be sent to the client.
+func getEvent(
+	ctx context.Context,
+	request *gomatrixserverlib.FederationRequest,
+	query api.RoomserverQueryAPI,
+	eventID string,
+) (*gomatrixserverlib.Event, *util.JSONResponse) {
+	var authResponse api.QueryServerAllowedToSeeEventResponse
+	err := query.QueryServerAllowedToSeeEvent(
+		ctx,
+		&api.QueryServerAllowedToSeeEventRequest{
+			EventID:    eventID,
+			ServerName: request.Origin(),
+		},
+		&authResponse,
+	)
+	if err != nil {
+		resErr := util.ErrorResponse(err)
+		return nil, &resErr
+	}
+
+	if !authResponse.AllowedToSeeEvent {
+		resErr := util.MessageResponse(http.StatusForbidden, "server not allowed to see event")
+		return nil, &resErr
+	}
+
+	var eventsResponse api.QueryEventsByIDResponse
+	err = query.QueryEventsByID(
+		ctx,
+		&api.QueryEventsByIDRequest{EventIDs: []string{eventID}},
+		&eventsResponse,
+	)
+	if err != nil {
+		resErr := util.ErrorResponse(err)
+		return nil, &resErr
+	}
+
+	if len(eventsResponse.Events) == 0 {
+		return nil, &util.JSONResponse{Code: http.StatusNotFound, JSON: nil}
+	}
+
+	return &eventsResponse.Events[0], nil
+}