Join room support in federation sender (#989)

* Implement PerformJoinRequest

* Rename perform functions

* Check send join response

* Temporary wiring to test federation sender room joins

* Actually pass through the config

* Make sure membership content shows join

federationsender/query/api.go

@@ -5,17 +5,37 @@ import (
 	"net/http"
 
 	"github.com/matrix-org/dendrite/common"
+	"github.com/matrix-org/dendrite/common/config"
 	"github.com/matrix-org/dendrite/federationsender/api"
+	"github.com/matrix-org/dendrite/federationsender/producers"
 	"github.com/matrix-org/dendrite/federationsender/storage"
-	rsAPI "github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
 )
 
 // FederationSenderInternalAPI is an implementation of api.FederationSenderInternalAPI
 type FederationSenderInternalAPI struct {
 	api.FederationSenderInternalAPI
-	DB                 storage.Database
-	RoomserverInputAPI rsAPI.RoomserverInputAPI
+	db         storage.Database
+	cfg        *config.Dendrite
+	producer   *producers.RoomserverProducer
+	federation *gomatrixserverlib.FederationClient
+	keyRing    *gomatrixserverlib.KeyRing
+}
+
+func NewFederationSenderInternalAPI(
+	db storage.Database, cfg *config.Dendrite,
+	producer *producers.RoomserverProducer,
+	federation *gomatrixserverlib.FederationClient,
+	keyRing *gomatrixserverlib.KeyRing,
+) *FederationSenderInternalAPI {
+	return &FederationSenderInternalAPI{
+		db:         db,
+		cfg:        cfg,
+		producer:   producer,
+		federation: federation,
+		keyRing:    keyRing,
+	}
 }
 
 // SetupHTTP adds the FederationSenderInternalAPI handlers to the http.ServeMux.
@@ -55,7 +75,7 @@ func (f *FederationSenderInternalAPI) SetupHTTP(servMux *http.ServeMux) {
 			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
 				return util.MessageResponse(http.StatusBadRequest, err.Error())
 			}
-			if err := f.PerformJoinRequest(req.Context(), &request, &response); err != nil {
+			if err := f.PerformJoin(req.Context(), &request, &response); err != nil {
 				return util.ErrorResponse(err)
 			}
 			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
@@ -68,7 +88,7 @@ func (f *FederationSenderInternalAPI) SetupHTTP(servMux *http.ServeMux) {
 			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
 				return util.MessageResponse(http.StatusBadRequest, err.Error())
 			}
-			if err := f.PerformLeaveRequest(req.Context(), &request, &response); err != nil {
+			if err := f.PerformLeave(req.Context(), &request, &response); err != nil {
 				return util.ErrorResponse(err)
 			}
 			return util.JSONResponse{Code: http.StatusOK, JSON: &response}

federationsender/query/perform.go

@@ -2,21 +2,116 @@ package query
 
 import (
 	"context"
+	"fmt"
+	"time"
 
 	"github.com/matrix-org/dendrite/federationsender/api"
+	"github.com/matrix-org/dendrite/federationsender/query/perform"
+	"github.com/matrix-org/dendrite/roomserver/version"
+	"github.com/matrix-org/gomatrixserverlib"
 )
 
 // PerformJoinRequest implements api.FederationSenderInternalAPI
-func (r *FederationSenderInternalAPI) PerformJoinRequest(
+func (r *FederationSenderInternalAPI) PerformJoin(
 	ctx context.Context,
 	request *api.PerformJoinRequest,
 	response *api.PerformJoinResponse,
 ) (err error) {
+	// Look up the supported room versions.
+	var supportedVersions []gomatrixserverlib.RoomVersion
+	for version := range version.SupportedRoomVersions() {
+		supportedVersions = append(supportedVersions, version)
+	}
+
+	// Try to perform a make_join using the information supplied in the
+	// request.
+	respMakeJoin, err := r.federation.MakeJoin(
+		ctx,
+		request.ServerName,
+		request.RoomID,
+		request.UserID,
+		supportedVersions,
+	)
+	if err != nil {
+		// TODO: Check if the user was not allowed to join the room.
+		return fmt.Errorf("r.federation.MakeJoin: %w", err)
+	}
+
+	// Set all the fields to be what they should be, this should be a no-op
+	// but it's possible that the remote server returned us something "odd"
+	respMakeJoin.JoinEvent.Type = "m.room.member"
+	respMakeJoin.JoinEvent.Sender = request.UserID
+	respMakeJoin.JoinEvent.StateKey = &request.UserID
+	respMakeJoin.JoinEvent.RoomID = request.RoomID
+	respMakeJoin.JoinEvent.Redacts = ""
+	if request.Content == nil {
+		request.Content = map[string]interface{}{}
+	}
+	request.Content["membership"] = "join"
+	if err = respMakeJoin.JoinEvent.SetContent(request.Content); err != nil {
+		return fmt.Errorf("respMakeJoin.JoinEvent.SetContent: %w", err)
+	}
+	if err = respMakeJoin.JoinEvent.SetUnsigned(struct{}{}); err != nil {
+		return fmt.Errorf("respMakeJoin.JoinEvent.SetUnsigned: %w", err)
+	}
+
+	// Work out if we support the room version that has been supplied in
+	// the make_join response.
+	if respMakeJoin.RoomVersion == "" {
+		respMakeJoin.RoomVersion = gomatrixserverlib.RoomVersionV1
+	}
+	if _, err = respMakeJoin.RoomVersion.EventFormat(); err != nil {
+		return fmt.Errorf("respMakeJoin.RoomVersion.EventFormat: %w", err)
+	}
+
+	// Build the join event.
+	event, err := respMakeJoin.JoinEvent.Build(
+		time.Now(),
+		r.cfg.Matrix.ServerName,
+		r.cfg.Matrix.KeyID,
+		r.cfg.Matrix.PrivateKey,
+		respMakeJoin.RoomVersion,
+	)
+	if err != nil {
+		return fmt.Errorf("respMakeJoin.JoinEvent.Build: %w", err)
+	}
+
+	// Try to perform a send_join using the newly built event.
+	respSendJoin, err := r.federation.SendJoin(
+		ctx,
+		request.ServerName,
+		event,
+		respMakeJoin.RoomVersion,
+	)
+	if err != nil {
+		return fmt.Errorf("r.federation.SendJoin: %w", err)
+	}
+
+	// Check that the send_join response was valid.
+	joinCtx := perform.JoinContext(r.federation, r.keyRing)
+	if err = joinCtx.CheckSendJoinResponse(
+		ctx, event, request.ServerName, respMakeJoin, respSendJoin,
+	); err != nil {
+		return fmt.Errorf("perform.JoinRequest.CheckSendJoinResponse: %w", err)
+	}
+
+	// If we successfully performed a send_join above then the other
+	// server now thinks we're a part of the room. Send the newly
+	// returned state to the roomserver to update our local view.
+	if err = r.producer.SendEventWithState(
+		ctx,
+		respSendJoin.ToRespState(),
+		event.Headered(respMakeJoin.RoomVersion),
+	); err != nil {
+		return fmt.Errorf("r.producer.SendEventWithState: %w", err)
+	}
+
+	// Everything went to plan.
 	return nil
 }
 
 // PerformLeaveRequest implements api.FederationSenderInternalAPI
-func (r *FederationSenderInternalAPI) PerformLeaveRequest(
+func (r *FederationSenderInternalAPI) PerformLeave(
 	ctx context.Context,
 	request *api.PerformLeaveRequest,
 	response *api.PerformLeaveResponse,

federationsender/query/perform/join.go

@@ -0,0 +1,70 @@
+package perform
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+// This file contains helpers for the PerformJoin function.
+
+type joinContext struct {
+	federation *gomatrixserverlib.FederationClient
+	keyRing    *gomatrixserverlib.KeyRing
+}
+
+// Returns a new join context.
+func JoinContext(f *gomatrixserverlib.FederationClient, k *gomatrixserverlib.KeyRing) *joinContext {
+	return &joinContext{
+		federation: f,
+		keyRing:    k,
+	}
+}
+
+// checkSendJoinResponse checks that all of the signatures are correct
+// and that the join is allowed by the supplied state.
+func (r joinContext) CheckSendJoinResponse(
+	ctx context.Context,
+	event gomatrixserverlib.Event,
+	server gomatrixserverlib.ServerName,
+	respMakeJoin gomatrixserverlib.RespMakeJoin,
+	respSendJoin gomatrixserverlib.RespSendJoin,
+) error {
+	// A list of events that we have retried, if they were not included in
+	// the auth events supplied in the send_join.
+	retries := map[string]bool{}
+
+retryCheck:
+	// TODO: Can we expand Check here to return a list of missing auth
+	// events rather than failing one at a time?
+	if err := respSendJoin.Check(ctx, r.keyRing, event); err != nil {
+		switch e := err.(type) {
+		case gomatrixserverlib.MissingAuthEventError:
+			// Check that we haven't already retried for this event, prevents
+			// us from ending up in endless loops
+			if !retries[e.AuthEventID] {
+				// Ask the server that we're talking to right now for the event
+				tx, txerr := r.federation.GetEvent(ctx, server, e.AuthEventID)
+				if txerr != nil {
+					return fmt.Errorf("r.federation.GetEvent: %w", txerr)
+				}
+				// For each event returned, add it to the auth events.
+				for _, pdu := range tx.PDUs {
+					ev, everr := gomatrixserverlib.NewEventFromUntrustedJSON(pdu, respMakeJoin.RoomVersion)
+					if everr != nil {
+						return fmt.Errorf("gomatrixserverlib.NewEventFromUntrustedJSON: %w", everr)
+					}
+					respSendJoin.AuthEvents = append(respSendJoin.AuthEvents, ev)
+				}
+				// Mark the event as retried and then give the check another go.
+				retries[e.AuthEventID] = true
+				goto retryCheck
+			}
+			return fmt.Errorf("respSendJoin (after retries): %w", e)
+		default:
+			return fmt.Errorf("respSendJoin: %w", err)
+		}
+	}
+	return nil
+}

federationsender/query/query.go

@@ -13,7 +13,7 @@ func (f *FederationSenderInternalAPI) QueryJoinedHostsInRoom(
 	request *api.QueryJoinedHostsInRoomRequest,
 	response *api.QueryJoinedHostsInRoomResponse,
 ) (err error) {
-	response.JoinedHosts, err = f.DB.GetJoinedHosts(ctx, request.RoomID)
+	response.JoinedHosts, err = f.db.GetJoinedHosts(ctx, request.RoomID)
 	return
 }
 
@@ -23,7 +23,7 @@ func (f *FederationSenderInternalAPI) QueryJoinedHostServerNamesInRoom(
 	request *api.QueryJoinedHostServerNamesInRoomRequest,
 	response *api.QueryJoinedHostServerNamesInRoomResponse,
 ) (err error) {
-	joinedHosts, err := f.DB.GetJoinedHosts(ctx, request.RoomID)
+	joinedHosts, err := f.db.GetJoinedHosts(ctx, request.RoomID)
 	if err != nil {
 		return
 	}