Don't generate event IDs unless needed

clientapi/routing/createroom.go

@@ -379,7 +379,14 @@ func buildEvent(
 		return nil, err
 	}
 	builder.AuthEvents = refs
-	eventID := fmt.Sprintf("$%s:%s", util.RandomString(16), cfg.Matrix.ServerName)
+	eventID := ""
+	eventIDFormat, err := roomVersion.EventIDFormat()
+	if err != nil {
+		return nil, err
+	}
+	if eventIDFormat == gomatrixserverlib.EventIDFormatV1 {
+		eventID = fmt.Sprintf("$%s:%s", util.RandomString(16), cfg.Matrix.ServerName)
+	}
 	event, err := builder.Build(
 		eventID, evTime, cfg.Matrix.ServerName, cfg.Matrix.KeyID,
 		cfg.Matrix.PrivateKey, roomVersion,

clientapi/routing/joinroom.go

@@ -335,7 +335,14 @@ func (r joinRoomReq) joinRoomUsingServer(roomID string, server gomatrixserverlib
 		}, nil
 	}
 
-	eventID := fmt.Sprintf("$%s:%s", util.RandomString(16), r.cfg.Matrix.ServerName)
+	eventID := ""
+	eventIDFormat, err := respMakeJoin.RoomVersion.EventIDFormat()
+	if err != nil {
+		return nil, err
+	}
+	if eventIDFormat == gomatrixserverlib.EventIDFormatV1 {
+		eventID = fmt.Sprintf("$%s:%s", util.RandomString(16), r.cfg.Matrix.ServerName)
+	}
 	event, err := respMakeJoin.JoinEvent.Build(
 		eventID, r.evTime, r.cfg.Matrix.ServerName, r.cfg.Matrix.KeyID,
 		r.cfg.Matrix.PrivateKey, respMakeJoin.RoomVersion,

common/events.go

@@ -51,13 +51,12 @@ func BuildEvent(
 		return nil, err
 	}
 
-	var eventID string
+	eventID := ""
-	var format gomatrixserverlib.EventIDFormat
+	eventIDFormat, err := queryRes.RoomVersion.EventIDFormat()
-	format, err = queryRes.RoomVersion.EventIDFormat()
 	if err != nil {
 		return nil, err
 	}
-	if format == gomatrixserverlib.EventIDFormatV1 {
+	if eventIDFormat == gomatrixserverlib.EventIDFormatV1 {
 		eventID = fmt.Sprintf("$%s:%s", util.RandomString(16), cfg.Matrix.ServerName)
 	}
 

federationapi/routing/threepid.go

@@ -280,7 +280,14 @@ func buildMembershipEvent(
 	}
 	builder.AuthEvents = refs
 
-	eventID := fmt.Sprintf("$%s:%s", util.RandomString(16), cfg.Matrix.ServerName)
+	eventID := ""
+	eventIDFormat, err := queryRes.RoomVersion.EventIDFormat()
+	if err != nil {
+		return nil, err
+	}
+	if eventIDFormat == gomatrixserverlib.EventIDFormatV1 {
+		eventID = fmt.Sprintf("$%s:%s", util.RandomString(16), cfg.Matrix.ServerName)
+	}
 	event, err := builder.Build(
 		eventID, time.Now(), cfg.Matrix.ServerName, cfg.Matrix.KeyID,
 		cfg.Matrix.PrivateKey, queryRes.RoomVersion,

go.mod

@@ -9,7 +9,7 @@ require (
 	github.com/matrix-org/go-http-js-libp2p v0.0.0-20200318135427-31631a9ef51f
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20200304164012-aa524245b658
 	github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20200320164238-a144ea149d55
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20200323100819-422881c3d06b
 	github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1
 	github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7
 	github.com/mattn/go-sqlite3 v2.0.2+incompatible

go.sum

@@ -130,6 +130,12 @@ github.com/matrix-org/gomatrixserverlib v0.0.0-20200124100636-0c2ec91d1df5 h1:km
 github.com/matrix-org/gomatrixserverlib v0.0.0-20200124100636-0c2ec91d1df5/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20200320164238-a144ea149d55 h1:1m/D/bEL+NqtW2PWko7Q7i9lekcegN+K3STLK4D/CFM=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20200320164238-a144ea149d55/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200323094202-39ec5e17a8f5 h1:hmC78piVeAvvdjuQ+zjnkyEmlAjR2gGwMWQh79srtAM=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200323094202-39ec5e17a8f5/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200323095935-e6d3df15dbfe h1:Zt5rFJriUGlCm+x8RRc3LdSqy0e6EaEWzW+PJXv76zw=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200323095935-e6d3df15dbfe/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200323100819-422881c3d06b h1:QrO9XkmoR+kbPwRmjcNl2crTt6XGXKcpsCyV/nZJDd0=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200323100819-422881c3d06b/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
 github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1 h1:osLoFdOy+ChQqVUn2PeTDETFftVkl4w9t/OW18g3lnk=
 github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1/go.mod h1:cXoYQIENbdWIQHt1SyCo6Bl3C3raHwJ0wgVrXHSqf+A=
 github.com/matrix-org/util v0.0.0-20171127121716-2e2df66af2f5 h1:W7l5CP4V7wPyPb4tYE11dbmeAOwtFQBTW0rf4OonOS8=

roomserver/alias/alias.go

@@ -250,7 +250,14 @@ func (r *RoomserverAliasAPI) sendUpdatedAliasesEvent(
 	}
 
 	// Build the event
-	eventID := fmt.Sprintf("$%s:%s", util.RandomString(16), r.Cfg.Matrix.ServerName)
+	eventID := ""
+	eventIDFormat, err := roomVersion.EventIDFormat()
+	if err != nil {
+		return err
+	}
+	if eventIDFormat == gomatrixserverlib.EventIDFormatV1 {
+		eventID = fmt.Sprintf("$%s:%s", util.RandomString(16), r.Cfg.Matrix.ServerName)
+	}
 	now := time.Now()
 	event, err := builder.Build(
 		eventID, now, r.Cfg.Matrix.ServerName, r.Cfg.Matrix.KeyID,

roomserver/version/version.go

@@ -43,11 +43,11 @@ var roomVersions = map[gomatrixserverlib.RoomVersion]RoomVersionDescription{
 		Stable:    true,
 	},
 	gomatrixserverlib.RoomVersionV3: RoomVersionDescription{
-		Supported: false,
+		Supported: true,
 		Stable:    false,
 	},
 	gomatrixserverlib.RoomVersionV4: RoomVersionDescription{
-		Supported: false,
+		Supported: true,
 		Stable:    false,
 	},
 	gomatrixserverlib.RoomVersionV5: RoomVersionDescription{
@@ -59,7 +59,7 @@ var roomVersions = map[gomatrixserverlib.RoomVersion]RoomVersionDescription{
 // DefaultRoomVersion contains the room version that will, by
 // default, be used to create new rooms on this server.
 func DefaultRoomVersion() gomatrixserverlib.RoomVersion {
-	return gomatrixserverlib.RoomVersionV2
+	return gomatrixserverlib.RoomVersionV4
 }
 
 // RoomVersions returns a map of all known room versions to this