Move SendJoin logic to GMSL (#3084)

Moves the core matrix logic for handling the send_join endpoint over to
gmsl.

2 files changed, 130 insertions, 217 deletions

diff --git a/federationapi/routing/join.go b/federationapi/routing/join.go
index cc22690a..cbdeca51 100644
--- a/federationapi/routing/join.go
+++ b/federationapi/routing/join.go
@@ -16,7 +16,6 @@ package routing
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"net/http"
 	"sort"
@@ -160,45 +159,43 @@ func MakeJoin(
 		BuildEventTemplate: createJoinTemplate,
 	}
 	response, internalErr := gomatrixserverlib.HandleMakeJoin(input)
-	if internalErr != nil {
-		switch e := internalErr.(type) {
-		case nil:
-		case spec.InternalServerError:
-			util.GetLogger(httpReq.Context()).WithError(internalErr)
-			return util.JSONResponse{
-				Code: http.StatusInternalServerError,
-				JSON: spec.InternalServerError{},
-			}
-		case spec.MatrixError:
-			util.GetLogger(httpReq.Context()).WithError(internalErr)
-			code := http.StatusInternalServerError
-			switch e.ErrCode {
-			case spec.ErrorForbidden:
-				code = http.StatusForbidden
-			case spec.ErrorNotFound:
-				code = http.StatusNotFound
-			case spec.ErrorUnableToAuthoriseJoin:
-				code = http.StatusBadRequest
-			case spec.ErrorBadJSON:
-				code = http.StatusBadRequest
-			}
+	switch e := internalErr.(type) {
+	case nil:
+	case spec.InternalServerError:
+		util.GetLogger(httpReq.Context()).WithError(internalErr)
+		return util.JSONResponse{
+			Code: http.StatusInternalServerError,
+			JSON: spec.InternalServerError{},
+		}
+	case spec.MatrixError:
+		util.GetLogger(httpReq.Context()).WithError(internalErr)
+		code := http.StatusInternalServerError
+		switch e.ErrCode {
+		case spec.ErrorForbidden:
+			code = http.StatusForbidden
+		case spec.ErrorNotFound:
+			code = http.StatusNotFound
+		case spec.ErrorUnableToAuthoriseJoin:
+			fallthrough // http.StatusBadRequest
+		case spec.ErrorBadJSON:
+			code = http.StatusBadRequest
+		}
 
-			return util.JSONResponse{
-				Code: code,
-				JSON: e,
-			}
-		case spec.IncompatibleRoomVersionError:
-			util.GetLogger(httpReq.Context()).WithError(internalErr)
-			return util.JSONResponse{
-				Code: http.StatusBadRequest,
-				JSON: e,
-			}
-		default:
-			util.GetLogger(httpReq.Context()).WithError(internalErr)
-			return util.JSONResponse{
-				Code: http.StatusBadRequest,
-				JSON: spec.Unknown("unknown error"),
-			}
+		return util.JSONResponse{
+			Code: code,
+			JSON: e,
+		}
+	case spec.IncompatibleRoomVersionError:
+		util.GetLogger(httpReq.Context()).WithError(internalErr)
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: e,
+		}
+	default:
+		util.GetLogger(httpReq.Context()).WithError(internalErr)
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: spec.Unknown("unknown error"),
 		}
 	}
 
@@ -219,6 +216,25 @@ func MakeJoin(
 	}
 }
 
+type MembershipQuerier struct {
+	roomserver api.FederationRoomserverAPI
+}
+
+func (mq *MembershipQuerier) CurrentMembership(ctx context.Context, roomID spec.RoomID, userID spec.UserID) (string, error) {
+	req := api.QueryMembershipForUserRequest{
+		RoomID: roomID.String(),
+		UserID: userID.String(),
+	}
+	res := api.QueryMembershipForUserResponse{}
+	err := mq.roomserver.QueryMembershipForUser(ctx, &req, &res)
+
+	membership := ""
+	if err == nil {
+		membership = res.Membership
+	}
+	return membership, err
+}
+
 // SendJoin implements the /send_join API
 // The make-join send-join dance makes much more sense as a single
 // flow so the cyclomatic complexity is high:
@@ -229,9 +245,10 @@ func SendJoin(
 	cfg *config.FederationAPI,
 	rsAPI api.FederationRoomserverAPI,
 	keys gomatrixserverlib.JSONVerifier,
-	roomID, eventID string,
+	roomID spec.RoomID,
+	eventID string,
 ) util.JSONResponse {
-	roomVersion, err := rsAPI.QueryRoomVersionForRoom(httpReq.Context(), roomID)
+	roomVersion, err := rsAPI.QueryRoomVersionForRoom(httpReq.Context(), roomID.String())
 	if err != nil {
 		util.GetLogger(httpReq.Context()).WithError(err).Error("rsAPI.QueryRoomVersionForRoom failed")
 		return util.JSONResponse{
@@ -239,132 +256,71 @@ func SendJoin(
 			JSON: spec.InternalServerError{},
 		}
 	}
-	verImpl, err := gomatrixserverlib.GetRoomVersion(roomVersion)
-	if err != nil {
-		return util.JSONResponse{
-			Code: http.StatusInternalServerError,
-			JSON: spec.UnsupportedRoomVersion(
-				fmt.Sprintf("QueryRoomVersionForRoom returned unknown room version: %s", roomVersion),
-			),
-		}
-	}
 
-	event, err := verImpl.NewEventFromUntrustedJSON(request.Content())
-	if err != nil {
+	input := gomatrixserverlib.HandleSendJoinInput{
+		Context:           httpReq.Context(),
+		RoomID:            roomID,
+		EventID:           eventID,
+		JoinEvent:         request.Content(),
+		RoomVersion:       roomVersion,
+		RequestOrigin:     request.Origin(),
+		LocalServerName:   cfg.Matrix.ServerName,
+		KeyID:             cfg.Matrix.KeyID,
+		PrivateKey:        cfg.Matrix.PrivateKey,
+		Verifier:          keys,
+		MembershipQuerier: &MembershipQuerier{roomserver: rsAPI},
+	}
+	response, joinErr := gomatrixserverlib.HandleSendJoin(input)
+	switch e := joinErr.(type) {
+	case nil:
+	case spec.InternalServerError:
+		util.GetLogger(httpReq.Context()).WithError(joinErr)
 		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("The request body could not be decoded into valid JSON: " + err.Error()),
-		}
-	}
-
-	// Check that a state key is provided.
-	if event.StateKey() == nil || event.StateKeyEquals("") {
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("No state key was provided in the join event."),
-		}
-	}
-	if !event.StateKeyEquals(event.Sender()) {
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("Event state key must match the event sender."),
-		}
-	}
-
-	// Check that the sender belongs to the server that is sending us
-	// the request. By this point we've already asserted that the sender
-	// and the state key are equal so we don't need to check both.
-	var serverName spec.ServerName
-	if _, serverName, err = gomatrixserverlib.SplitID('@', event.Sender()); err != nil {
-		return util.JSONResponse{
-			Code: http.StatusForbidden,
-			JSON: spec.Forbidden("The sender of the join is invalid"),
+			Code: http.StatusInternalServerError,
+			JSON: spec.InternalServerError{},
 		}
-	} else if serverName != request.Origin() {
-		return util.JSONResponse{
-			Code: http.StatusForbidden,
-			JSON: spec.Forbidden("The sender does not match the server that originated the request"),
+	case spec.MatrixError:
+		util.GetLogger(httpReq.Context()).WithError(joinErr)
+		code := http.StatusInternalServerError
+		switch e.ErrCode {
+		case spec.ErrorForbidden:
+			code = http.StatusForbidden
+		case spec.ErrorNotFound:
+			code = http.StatusNotFound
+		case spec.ErrorUnsupportedRoomVersion:
+			code = http.StatusInternalServerError
+		case spec.ErrorBadJSON:
+			code = http.StatusBadRequest
 		}
-	}
 
-	// Check that the room ID is correct.
-	if event.RoomID() != roomID {
 		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON(
-				fmt.Sprintf(
-					"The room ID in the request path (%q) must match the room ID in the join event JSON (%q)",
-					roomID, event.RoomID(),
-				),
-			),
+			Code: code,
+			JSON: e,
 		}
-	}
-
-	// Check that the event ID is correct.
-	if event.EventID() != eventID {
+	default:
+		util.GetLogger(httpReq.Context()).WithError(joinErr)
 		return util.JSONResponse{
 			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON(
-				fmt.Sprintf(
-					"The event ID in the request path (%q) must match the event ID in the join event JSON (%q)",
-					eventID, event.EventID(),
-				),
-			),
+			JSON: spec.Unknown("unknown error"),
 		}
 	}
 
-	// Check that this is in fact a join event
-	membership, err := event.Membership()
-	if err != nil {
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("missing content.membership key"),
-		}
-	}
-	if membership != spec.Join {
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("membership must be 'join'"),
-		}
-	}
-
-	// Check that the event is signed by the server sending the request.
-	redacted, err := verImpl.RedactEventJSON(event.JSON())
-	if err != nil {
-		logrus.WithError(err).Errorf("XXX: join.go")
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON("The event JSON could not be redacted"),
-		}
-	}
-	verifyRequests := []gomatrixserverlib.VerifyJSONRequest{{
-		ServerName:             serverName,
-		Message:                redacted,
-		AtTS:                   event.OriginServerTS(),
-		StrictValidityChecking: true,
-	}}
-	verifyResults, err := keys.VerifyJSONs(httpReq.Context(), verifyRequests)
-	if err != nil {
-		util.GetLogger(httpReq.Context()).WithError(err).Error("keys.VerifyJSONs failed")
+	if response == nil {
+		util.GetLogger(httpReq.Context()).Error("gmsl.HandleMakeJoin returned invalid response")
 		return util.JSONResponse{
 			Code: http.StatusInternalServerError,
 			JSON: spec.InternalServerError{},
 		}
-	}
-	if verifyResults[0].Error != nil {
-		return util.JSONResponse{
-			Code: http.StatusForbidden,
-			JSON: spec.Forbidden("Signature check failed: " + verifyResults[0].Error.Error()),
-		}
+
 	}
 
 	// Fetch the state and auth chain. We do this before we send the events
 	// on, in case this fails.
 	var stateAndAuthChainResponse api.QueryStateAndAuthChainResponse
 	err = rsAPI.QueryStateAndAuthChain(httpReq.Context(), &api.QueryStateAndAuthChainRequest{
-		PrevEventIDs: event.PrevEventIDs(),
-		AuthEventIDs: event.AuthEventIDs(),
-		RoomID:       roomID,
+		PrevEventIDs: response.JoinEvent.PrevEventIDs(),
+		AuthEventIDs: response.JoinEvent.AuthEventIDs(),
+		RoomID:       roomID.String(),
 		ResolveState: true,
 	}, &stateAndAuthChainResponse)
 	if err != nil {
@@ -388,84 +344,27 @@ func SendJoin(
 		}
 	}
 
-	// Check if the user is already in the room. If they're already in then
-	// there isn't much point in sending another join event into the room.
-	// Also check to see if they are banned: if they are then we reject them.
-	alreadyJoined := false
-	isBanned := false
-	for _, se := range stateAndAuthChainResponse.StateEvents {
-		if !se.StateKeyEquals(*event.StateKey()) {
-			continue
-		}
-		if membership, merr := se.Membership(); merr == nil {
-			alreadyJoined = (membership == spec.Join)
-			isBanned = (membership == spec.Ban)
-			break
-		}
-	}
-
-	if isBanned {
-		return util.JSONResponse{
-			Code: http.StatusForbidden,
-			JSON: spec.Forbidden("user is banned"),
-		}
-	}
-
-	// If the membership content contains a user ID for a server that is not
-	// ours then we should kick it back.
-	var memberContent gomatrixserverlib.MemberContent
-	if err := json.Unmarshal(event.Content(), &memberContent); err != nil {
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: spec.BadJSON(err.Error()),
-		}
-	}
-	if memberContent.AuthorisedVia != "" {
-		_, domain, err := gomatrixserverlib.SplitID('@', memberContent.AuthorisedVia)
-		if err != nil {
-			return util.JSONResponse{
-				Code: http.StatusBadRequest,
-				JSON: spec.BadJSON(fmt.Sprintf("The authorising username %q is invalid.", memberContent.AuthorisedVia)),
-			}
-		}
-		if domain != cfg.Matrix.ServerName {
-			return util.JSONResponse{
-				Code: http.StatusBadRequest,
-				JSON: spec.BadJSON(fmt.Sprintf("The authorising username %q does not belong to this server.", memberContent.AuthorisedVia)),
-			}
-		}
-	}
-
-	// Sign the membership event. This is required for restricted joins to work
-	// in the case that the authorised via user is one of our own users. It also
-	// doesn't hurt to do it even if it isn't a restricted join.
-	signed := event.Sign(
-		string(cfg.Matrix.ServerName),
-		cfg.Matrix.KeyID,
-		cfg.Matrix.PrivateKey,
-	)
-
 	// Send the events to the room server.
 	// We are responsible for notifying other servers that the user has joined
 	// the room, so set SendAsServer to cfg.Matrix.ServerName
-	if !alreadyJoined {
-		var response api.InputRoomEventsResponse
+	if !response.AlreadyJoined {
+		var rsResponse api.InputRoomEventsResponse
 		rsAPI.InputRoomEvents(httpReq.Context(), &api.InputRoomEventsRequest{
 			InputRoomEvents: []api.InputRoomEvent{
 				{
 					Kind:          api.KindNew,
-					Event:         &types.HeaderedEvent{PDU: signed},
+					Event:         &types.HeaderedEvent{PDU: response.JoinEvent},
 					SendAsServer:  string(cfg.Matrix.ServerName),
 					TransactionID: nil,
 				},
 			},
-		}, &response)
-		if response.ErrMsg != "" {
-			util.GetLogger(httpReq.Context()).WithField(logrus.ErrorKey, response.ErrMsg).Error("SendEvents failed")
-			if response.NotAllowed {
+		}, &rsResponse)
+		if rsResponse.ErrMsg != "" {
+			util.GetLogger(httpReq.Context()).WithField(logrus.ErrorKey, rsResponse.ErrMsg).Error("SendEvents failed")
+			if rsResponse.NotAllowed {
 				return util.JSONResponse{
 					Code: http.StatusBadRequest,
-					JSON: spec.Forbidden(response.ErrMsg),
+					JSON: spec.Forbidden(rsResponse.ErrMsg),
 				}
 			}
 			return util.JSONResponse{
@@ -488,7 +387,7 @@ func SendJoin(
 			StateEvents: types.NewEventJSONsFromHeaderedEvents(stateAndAuthChainResponse.StateEvents),
 			AuthEvents:  types.NewEventJSONsFromHeaderedEvents(stateAndAuthChainResponse.AuthChainEvents),
 			Origin:      cfg.Matrix.ServerName,
-			Event:       signed.JSON(),
+			Event:       response.JoinEvent.JSON(),
 		},
 	}
 }
diff --git a/federationapi/routing/routing.go b/federationapi/routing/routing.go
index 44faad91..7be0857a 100644
--- a/federationapi/routing/routing.go
+++ b/federationapi/routing/routing.go
@@ -331,14 +331,14 @@ func Setup(
 			if err != nil {
 				return util.JSONResponse{
 					Code: http.StatusBadRequest,
-					JSON: spec.BadJSON("Invalid UserID"),
+					JSON: spec.InvalidParam("Invalid UserID"),
 				}
 			}
 			roomID, err := spec.NewRoomID(vars["roomID"])
 			if err != nil {
 				return util.JSONResponse{
 					Code: http.StatusBadRequest,
-					JSON: spec.BadJSON("Invalid RoomID"),
+					JSON: spec.InvalidParam("Invalid RoomID"),
 				}
 			}
 
@@ -358,10 +358,17 @@ func Setup(
 					JSON: spec.Forbidden("Forbidden by server ACLs"),
 				}
 			}
-			roomID := vars["roomID"]
 			eventID := vars["eventID"]
+			roomID, err := spec.NewRoomID(vars["roomID"])
+			if err != nil {
+				return util.JSONResponse{
+					Code: http.StatusBadRequest,
+					JSON: spec.InvalidParam("Invalid RoomID"),
+				}
+			}
+
 			res := SendJoin(
-				httpReq, request, cfg, rsAPI, keys, roomID, eventID,
+				httpReq, request, cfg, rsAPI, keys, *roomID, eventID,
 			)
 			// not all responses get wrapped in [code, body]
 			var body interface{}
@@ -390,10 +397,17 @@ func Setup(
 					JSON: spec.Forbidden("Forbidden by server ACLs"),
 				}
 			}
-			roomID := vars["roomID"]
 			eventID := vars["eventID"]
+			roomID, err := spec.NewRoomID(vars["roomID"])
+			if err != nil {
+				return util.JSONResponse{
+					Code: http.StatusBadRequest,
+					JSON: spec.InvalidParam("Invalid RoomID"),
+				}
+			}
+
 			return SendJoin(
-				httpReq, request, cfg, rsAPI, keys, roomID, eventID,
+				httpReq, request, cfg, rsAPI, keys, *roomID, eventID,
 			)
 		},
 	)).Methods(http.MethodPut)