Add room version to room create request, persist in storage (#915)

* Add room version into createRoomReq

* Extract room version from m.room.create event when persisting

* Reduce cyclomatic complexity

* Update whitelist, gomatrixserverlib, tweaks to roomserver

* Update sytest-whitelist again

roomserver/storage/postgres/storage.go

@@ -18,6 +18,9 @@ package postgres
 import (
 	"context"
 	"database/sql"
+	"encoding/json"
+
+	roomserverVersion "github.com/matrix-org/dendrite/roomserver/version"
 
 	// Import the postgres database driver.
 	_ "github.com/lib/pq"
@@ -68,8 +71,21 @@ func (d *Database) StoreEvent(
 		}
 	}
 
-	// TODO: Room version here
-	if roomNID, err = d.assignRoomNID(ctx, nil, event.RoomID(), "1"); err != nil {
+	// TODO: Here we should aim to have two different code paths for new rooms
+	// vs existing ones.
+
+	// Get the default room version. If the client doesn't supply a room_version
+	// then we will use our configured default to create the room.
+	// https://matrix.org/docs/spec/client_server/r0.6.0#post-matrix-client-r0-createroom
+	// Note that the below logic depends on the m.room.create event being the
+	// first event that is persisted to the database when creating or joining a
+	// room.
+	var roomVersion gomatrixserverlib.RoomVersion
+	if roomVersion, err = extractRoomVersionFromCreateEvent(event); err != nil {
+		return 0, types.StateAtEvent{}, err
+	}
+
+	if roomNID, err = d.assignRoomNID(ctx, nil, event.RoomID(), roomVersion); err != nil {
 		return 0, types.StateAtEvent{}, err
 	}
 
@@ -121,6 +137,29 @@ func (d *Database) StoreEvent(
 	}, nil
 }
 
+func extractRoomVersionFromCreateEvent(event gomatrixserverlib.Event) (
+	gomatrixserverlib.RoomVersion, error,
+) {
+	var err error
+	var roomVersion gomatrixserverlib.RoomVersion
+	// Look for m.room.create events.
+	if event.Type() != gomatrixserverlib.MRoomCreate {
+		return gomatrixserverlib.RoomVersion(""), nil
+	}
+	roomVersion = roomserverVersion.DefaultRoomVersion()
+	var createContent gomatrixserverlib.CreateContent
+	// The m.room.create event contains an optional "room_version" key in
+	// the event content, so we need to unmarshal that first.
+	if err = json.Unmarshal(event.Content(), &createContent); err != nil {
+		return gomatrixserverlib.RoomVersion(""), err
+	}
+	// A room version was specified in the event content?
+	if createContent.RoomVersion != nil {
+		roomVersion = *createContent.RoomVersion
+	}
+	return roomVersion, err
+}
+
 func (d *Database) assignRoomNID(
 	ctx context.Context, txn *sql.Tx,
 	roomID string, roomVersion gomatrixserverlib.RoomVersion,