[federation] Implement state APIs (#486)

* Refactor GetEvents

* [federationapi] Add state APIs

src/github.com/matrix-org/dendrite/federationapi/routing/events.go

@@ -35,6 +35,22 @@ func GetEvent(
 	_ gomatrixserverlib.KeyRing,
 	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,
@@ -45,11 +61,13 @@ func GetEvent(
 		&authResponse,
 	)
 	if err != nil {
-		return util.ErrorResponse(err)
+		resErr := util.ErrorResponse(err)
+		return nil, &resErr
 	}
 
 	if !authResponse.AllowedToSeeEvent {
-		return util.MessageResponse(http.StatusForbidden, "server not allowed to see event")
+		resErr := util.MessageResponse(http.StatusForbidden, "server not allowed to see event")
+		return nil, &resErr
 	}
 
 	var eventsResponse api.QueryEventsByIDResponse
@@ -59,12 +77,13 @@ func GetEvent(
 		&eventsResponse,
 	)
 	if err != nil {
-		return util.ErrorResponse(err)
+		resErr := util.ErrorResponse(err)
+		return nil, &resErr
 	}
 
 	if len(eventsResponse.Events) == 0 {
-		return util.JSONResponse{Code: http.StatusNotFound, JSON: nil}
+		return nil, &util.JSONResponse{Code: http.StatusNotFound, JSON: nil}
 	}
 
-	return util.JSONResponse{Code: http.StatusOK, JSON: &eventsResponse.Events[0]}
+	return &eventsResponse.Events[0], nil
 }

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

@@ -106,6 +106,28 @@ func Setup(
 		},
 	)).Methods(http.MethodGet)
 
+	v1fedmux.Handle("/state/{roomID}/{eventID}", common.MakeFedAPI(
+		"federation_get_event_auth", cfg.Matrix.ServerName, keys,
+		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
+			vars := mux.Vars(httpReq)
+			return GetState(
+				httpReq.Context(), request, cfg, query, time.Now(),
+				keys, vars["roomID"], vars["eventID"],
+			)
+		},
+	)).Methods(http.MethodGet)
+
+	v1fedmux.Handle("/state_ids/{roomID}/{eventID}", common.MakeFedAPI(
+		"federation_get_event_auth", cfg.Matrix.ServerName, keys,
+		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
+			vars := mux.Vars(httpReq)
+			return GetStateIDs(
+				httpReq.Context(), request, cfg, query, time.Now(),
+				keys, vars["roomID"], vars["eventID"],
+			)
+		},
+	)).Methods(http.MethodGet)
+
 	v1fedmux.Handle("/query/directory/", common.MakeFedAPI(
 		"federation_query_room_alias", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {

src/github.com/matrix-org/dendrite/federationapi/routing/state.go

@@ -0,0 +1,127 @@
+// 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"
+	"time"
+
+	"github.com/matrix-org/dendrite/common/config"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+// GetState returns state events & auth events for the roomID, eventID
+func GetState(
+	ctx context.Context,
+	request *gomatrixserverlib.FederationRequest,
+	_ config.Dendrite,
+	query api.RoomserverQueryAPI,
+	_ time.Time,
+	_ gomatrixserverlib.KeyRing,
+	roomID string,
+	eventID string,
+) util.JSONResponse {
+	state, err := getState(ctx, request, query, roomID, eventID)
+	if err != nil {
+		return *err
+	}
+
+	return util.JSONResponse{Code: http.StatusOK, JSON: state}
+}
+
+// GetStateIDs returns state event IDs & auth event IDs for the roomID, eventID
+func GetStateIDs(
+	ctx context.Context,
+	request *gomatrixserverlib.FederationRequest,
+	_ config.Dendrite,
+	query api.RoomserverQueryAPI,
+	_ time.Time,
+	_ gomatrixserverlib.KeyRing,
+	roomID string,
+	eventID string,
+) util.JSONResponse {
+	state, err := getState(ctx, request, query, roomID, eventID)
+	if err != nil {
+		return *err
+	}
+
+	stateEventIDs := getIDsFromEvent(state.StateEvents)
+	authEventIDs := getIDsFromEvent(state.AuthEvents)
+
+	return util.JSONResponse{Code: http.StatusOK, JSON: gomatrixserverlib.RespStateIDs{
+		StateEventIDs: stateEventIDs,
+		AuthEventIDs:  authEventIDs,
+	},
+	}
+}
+
+func getState(
+	ctx context.Context,
+	request *gomatrixserverlib.FederationRequest,
+	query api.RoomserverQueryAPI,
+	roomID string,
+	eventID string,
+) (*gomatrixserverlib.RespState, *util.JSONResponse) {
+	event, resErr := getEvent(ctx, request, query, eventID)
+	if resErr != nil {
+		return nil, resErr
+	}
+
+	prevEventIDs := getIDsFromEventRef(event.PrevEvents())
+	authEventIDs := getIDsFromEventRef(event.AuthEvents())
+
+	var response api.QueryStateAndAuthChainResponse
+	err := query.QueryStateAndAuthChain(
+		ctx,
+		&api.QueryStateAndAuthChainRequest{
+			RoomID:       roomID,
+			PrevEventIDs: prevEventIDs,
+			AuthEventIDs: authEventIDs,
+		},
+		&response,
+	)
+	if err != nil {
+		resErr := util.ErrorResponse(err)
+		return nil, &resErr
+	}
+
+	if !response.RoomExists {
+		return nil, &util.JSONResponse{Code: http.StatusNotFound, JSON: nil}
+	}
+
+	return &gomatrixserverlib.RespState{
+		StateEvents: response.StateEvents,
+		AuthEvents:  response.AuthChainEvents,
+	}, nil
+}
+
+func getIDsFromEventRef(events []gomatrixserverlib.EventReference) []string {
+	IDs := make([]string, len(events))
+	for i := range events {
+		IDs[i] = events[i].EventID
+	}
+
+	return IDs
+}
+
+func getIDsFromEvent(events []gomatrixserverlib.Event) []string {
+	IDs := make([]string, len(events))
+	for i := range events {
+		IDs[i] = events[i].EventID()
+	}
+
+	return IDs
+}