[federation] Add make_leave & send_leave (#535)

* [federation] Add make_leave & send_leave

* Remove redundant parameters

* Check membership is set to leave

Signed-off-by: Anant Prakash <anantprakashjsr@gmail.com>

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

@@ -0,0 +1,174 @@
+// 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/clientapi/producers"
+	"github.com/matrix-org/dendrite/common"
+	"github.com/matrix-org/dendrite/common/config"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+// MakeLeave implements the /make_leave API
+func MakeLeave(
+	httpReq *http.Request,
+	request *gomatrixserverlib.FederationRequest,
+	cfg config.Dendrite,
+	query api.RoomserverQueryAPI,
+	roomID, userID string,
+) util.JSONResponse {
+	_, domain, err := gomatrixserverlib.SplitID('@', userID)
+	if err != nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("Invalid UserID"),
+		}
+	}
+	if domain != request.Origin() {
+		return util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden("The leave must be sent by the server of the user"),
+		}
+	}
+
+	// Try building an event for the server
+	builder := gomatrixserverlib.EventBuilder{
+		Sender:   userID,
+		RoomID:   roomID,
+		Type:     "m.room.member",
+		StateKey: &userID,
+	}
+	err = builder.SetContent(map[string]interface{}{"membership": "leave"})
+	if err != nil {
+		return httputil.LogThenError(httpReq, err)
+	}
+
+	var queryRes api.QueryLatestEventsAndStateResponse
+	event, err := common.BuildEvent(httpReq.Context(), &builder, cfg, query, &queryRes)
+	if err == common.ErrRoomNoExists {
+		return util.JSONResponse{
+			Code: http.StatusNotFound,
+			JSON: jsonerror.NotFound("Room does not exist"),
+		}
+	} else if err != nil {
+		return httputil.LogThenError(httpReq, err)
+	}
+
+	// Check that the leave is allowed or not
+	stateEvents := make([]*gomatrixserverlib.Event, len(queryRes.StateEvents))
+	for i := range queryRes.StateEvents {
+		stateEvents[i] = &queryRes.StateEvents[i]
+	}
+	provider := gomatrixserverlib.NewAuthEvents(stateEvents)
+	if err = gomatrixserverlib.Allowed(*event, &provider); err != nil {
+		return util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden(err.Error()),
+		}
+	}
+
+	return util.JSONResponse{
+		Code: http.StatusOK,
+		JSON: map[string]interface{}{"event": builder},
+	}
+}
+
+// SendLeave implements the /send_leave API
+func SendLeave(
+	httpReq *http.Request,
+	request *gomatrixserverlib.FederationRequest,
+	cfg config.Dendrite,
+	producer *producers.RoomserverProducer,
+	keys gomatrixserverlib.KeyRing,
+	roomID, eventID string,
+) util.JSONResponse {
+	var event gomatrixserverlib.Event
+	if err := json.Unmarshal(request.Content(), &event); err != nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.NotJSON("The request body could not be decoded into valid JSON. " + err.Error()),
+		}
+	}
+
+	// Check that the room ID is correct.
+	if event.RoomID() != roomID {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("The room ID in the request path must match the room ID in the leave event JSON"),
+		}
+	}
+
+	// Check that the event ID is correct.
+	if event.EventID() != eventID {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("The event ID in the request path must match the event ID in the leave event JSON"),
+		}
+	}
+
+	// Check that the event is from the server sending the request.
+	if event.Origin() != request.Origin() {
+		return util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden("The leave must be sent by the server it originated on"),
+		}
+	}
+
+	// Check that the event is signed by the server sending the request.
+	verifyRequests := []gomatrixserverlib.VerifyJSONRequest{{
+		ServerName: event.Origin(),
+		Message:    event.Redact().JSON(),
+		AtTS:       event.OriginServerTS(),
+	}}
+	verifyResults, err := keys.VerifyJSONs(httpReq.Context(), verifyRequests)
+	if err != nil {
+		return httputil.LogThenError(httpReq, err)
+	}
+	if verifyResults[0].Error != nil {
+		return util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden("The leave must be signed by the server it originated on"),
+		}
+	}
+
+	// check membership is set to leave
+	mem, err := event.Membership()
+	if err != nil {
+		return httputil.LogThenError(httpReq, err)
+	} else if mem != "leave" {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("The membership in the event content must be set to leave"),
+		}
+	}
+
+	// Send the events to the room server.
+	// We are responsible for notifying other servers that the user has left
+	// the room, so set SendAsServer to cfg.Matrix.ServerName
+	_, err = producer.SendEvents(httpReq.Context(), []gomatrixserverlib.Event{event}, cfg.Matrix.ServerName, nil)
+	if err != nil {
+		return httputil.LogThenError(httpReq, err)
+	}
+
+	return util.JSONResponse{
+		Code: http.StatusOK,
+		JSON: struct{}{},
+	}
+}

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

@@ -182,6 +182,30 @@ func Setup(
 		},
 	)).Methods(http.MethodPut)
 
+	v1fedmux.Handle("/make_leave/{roomID}/{userID}", common.MakeFedAPI(
+		"federation_make_leave", cfg.Matrix.ServerName, keys,
+		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
+			vars := mux.Vars(httpReq)
+			roomID := vars["roomID"]
+			userID := vars["userID"]
+			return MakeLeave(
+				httpReq, request, cfg, query, roomID, userID,
+			)
+		},
+	)).Methods(http.MethodGet)
+
+	v1fedmux.Handle("/send_leave/{roomID}/{userID}", common.MakeFedAPI(
+		"federation_send_leave", cfg.Matrix.ServerName, keys,
+		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
+			vars := mux.Vars(httpReq)
+			roomID := vars["roomID"]
+			userID := vars["userID"]
+			return SendLeave(
+				httpReq, request, cfg, producer, keys, roomID, userID,
+			)
+		},
+	)).Methods(http.MethodPut)
+
 	v1fedmux.Handle("/version", common.MakeExternalAPI(
 		"federation_version",
 		func(httpReq *http.Request) util.JSONResponse {