use go module for dependencies (#594)

federationapi/routing/send.go

@@ -0,0 +1,219 @@
+// Copyright 2017 Vector Creations 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"
+	"encoding/json"
+	"fmt"
+	"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/config"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+// Send implements /_matrix/federation/v1/send/{txnID}
+func Send(
+	httpReq *http.Request,
+	request *gomatrixserverlib.FederationRequest,
+	txnID gomatrixserverlib.TransactionID,
+	cfg config.Dendrite,
+	query api.RoomserverQueryAPI,
+	producer *producers.RoomserverProducer,
+	keys gomatrixserverlib.KeyRing,
+	federation *gomatrixserverlib.FederationClient,
+) util.JSONResponse {
+
+	t := txnReq{
+		context:    httpReq.Context(),
+		query:      query,
+		producer:   producer,
+		keys:       keys,
+		federation: federation,
+	}
+	if err := json.Unmarshal(request.Content(), &t); err != nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.NotJSON("The request body could not be decoded into valid JSON. " + err.Error()),
+		}
+	}
+
+	t.Origin = request.Origin()
+	t.TransactionID = txnID
+	t.Destination = cfg.Matrix.ServerName
+
+	resp, err := t.processTransaction()
+	if err != nil {
+		return httputil.LogThenError(httpReq, err)
+	}
+
+	return util.JSONResponse{
+		Code: http.StatusOK,
+		JSON: resp,
+	}
+}
+
+type txnReq struct {
+	gomatrixserverlib.Transaction
+	context    context.Context
+	query      api.RoomserverQueryAPI
+	producer   *producers.RoomserverProducer
+	keys       gomatrixserverlib.KeyRing
+	federation *gomatrixserverlib.FederationClient
+}
+
+func (t *txnReq) processTransaction() (*gomatrixserverlib.RespSend, error) {
+	// Check the event signatures
+	if err := gomatrixserverlib.VerifyAllEventSignatures(t.context, t.PDUs, t.keys); err != nil {
+		return nil, err
+	}
+
+	// Process the events.
+	results := map[string]gomatrixserverlib.PDUResult{}
+	for _, e := range t.PDUs {
+		err := t.processEvent(e)
+		if err != nil {
+			// If the error is due to the event itself being bad then we skip
+			// it and move onto the next event. We report an error so that the
+			// sender knows that we have skipped processing it.
+			//
+			// However if the event is due to a temporary failure in our server
+			// such as a database being unavailable then we should bail, and
+			// hope that the sender will retry when we are feeling better.
+			//
+			// It is uncertain what we should do if an event fails because
+			// we failed to fetch more information from the sending server.
+			// For example if a request to /state fails.
+			// If we skip the event then we risk missing the event until we
+			// receive another event referencing it.
+			// If we bail and stop processing then we risk wedging incoming
+			// transactions from that server forever.
+			switch err.(type) {
+			case unknownRoomError:
+			case *gomatrixserverlib.NotAllowed:
+			default:
+				// Any other error should be the result of a temporary error in
+				// our server so we should bail processing the transaction entirely.
+				return nil, err
+			}
+			results[e.EventID()] = gomatrixserverlib.PDUResult{
+				Error: err.Error(),
+			}
+		} else {
+			results[e.EventID()] = gomatrixserverlib.PDUResult{}
+		}
+	}
+
+	// TODO: Process the EDUs.
+
+	return &gomatrixserverlib.RespSend{PDUs: results}, nil
+}
+
+type unknownRoomError struct {
+	roomID string
+}
+
+func (e unknownRoomError) Error() string { return fmt.Sprintf("unknown room %q", e.roomID) }
+
+func (t *txnReq) processEvent(e gomatrixserverlib.Event) error {
+	prevEventIDs := e.PrevEventIDs()
+
+	// Fetch the state needed to authenticate the event.
+	needed := gomatrixserverlib.StateNeededForAuth([]gomatrixserverlib.Event{e})
+	stateReq := api.QueryStateAfterEventsRequest{
+		RoomID:       e.RoomID(),
+		PrevEventIDs: prevEventIDs,
+		StateToFetch: needed.Tuples(),
+	}
+	var stateResp api.QueryStateAfterEventsResponse
+	if err := t.query.QueryStateAfterEvents(t.context, &stateReq, &stateResp); err != nil {
+		return err
+	}
+
+	if !stateResp.RoomExists {
+		// TODO: When synapse receives a message for a room it is not in it
+		// asks the remote server for the state of the room so that it can
+		// check if the remote server knows of a join "m.room.member" event
+		// that this server is unaware of.
+		// However generally speaking we should reject events for rooms we
+		// aren't a member of.
+		return unknownRoomError{e.RoomID()}
+	}
+
+	if !stateResp.PrevEventsExist {
+		return t.processEventWithMissingState(e)
+	}
+
+	// Check that the event is allowed by the state at the event.
+	if err := checkAllowedByState(e, stateResp.StateEvents); err != nil {
+		return err
+	}
+
+	// TODO: Check that the roomserver has a copy of all of the auth_events.
+	// TODO: Check that the event is allowed by its auth_events.
+
+	// pass the event to the roomserver
+	_, err := t.producer.SendEvents(t.context, []gomatrixserverlib.Event{e}, api.DoNotSendToOtherServers, nil)
+	return err
+}
+
+func checkAllowedByState(e gomatrixserverlib.Event, stateEvents []gomatrixserverlib.Event) error {
+	authUsingState := gomatrixserverlib.NewAuthEvents(nil)
+	for i := range stateEvents {
+		err := authUsingState.AddEvent(&stateEvents[i])
+		if err != nil {
+			return err
+		}
+	}
+	return gomatrixserverlib.Allowed(e, &authUsingState)
+}
+
+func (t *txnReq) processEventWithMissingState(e gomatrixserverlib.Event) error {
+	// We are missing the previous events for this events.
+	// This means that there is a gap in our view of the history of the
+	// room. There two ways that we can handle such a gap:
+	//   1) We can fill in the gap using /get_missing_events
+	//   2) We can leave the gap and request the state of the room at
+	//      this event from the remote server using either /state_ids
+	//      or /state.
+	// Synapse will attempt to do 1 and if that fails or if the gap is
+	// too large then it will attempt 2.
+	// Synapse will use /state_ids if possible since usually the state
+	// is largely unchanged and it is more efficient to fetch a list of
+	// event ids and then use /event to fetch the individual events.
+	// However not all version of synapse support /state_ids so you may
+	// need to fallback to /state.
+	// TODO: Attempt to fill in the gap using /get_missing_events
+	// TODO: Attempt to fetch the state using /state_ids and /events
+	state, err := t.federation.LookupState(t.context, t.Origin, e.RoomID(), e.EventID())
+	if err != nil {
+		return err
+	}
+	// Check that the returned state is valid.
+	if err := state.Check(t.context, t.keys); err != nil {
+		return err
+	}
+	// Check that the event is allowed by the state.
+	if err := checkAllowedByState(e, state.StateEvents); err != nil {
+		return err
+	}
+	// pass the event along with the state to the roomserver
+	return t.producer.SendEventWithState(t.context, state, e)
+}