dendrite/federationapi/routing/send.go

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// 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/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 {
util.GetLogger(httpReq.Context()).WithError(err).Error("t.processTransaction failed")
return jsonerror.InternalServerError()
}
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(),
}
util.GetLogger(t.context).WithError(err).WithField("event_id", e.EventID()).Warn("Failed to process incoming federation event, skipping it.")
} 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.
var events []gomatrixserverlib.Event
for _, headeredEvent := range stateResp.StateEvents {
events = append(events, headeredEvent.Event)
}
if err := checkAllowedByState(e, events); 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.
retryAllowedState:
if err := checkAllowedByState(e, state.StateEvents); err != nil {
switch missing := err.(type) {
case gomatrixserverlib.MissingAuthEventError:
// An auth event was missing so let's look up that event over federation
for _, s := range state.StateEvents {
if s.EventID() != missing.AuthEventID {
continue
}
err = t.processEventWithMissingState(s)
// If there was no error retrieving the event from federation then
// we assume that it succeeded, so retry the original state check
if err == nil {
goto retryAllowedState
}
}
default:
}
return err
}
// pass the event along with the state to the roomserver
return t.producer.SendEventWithState(t.context, state, e)
}