ENiGMA½ has many ways to add doors to your system. In addition to the [many built in door server modules](door-servers.md), local doors are of course also supported using the ! The `abracadabra` module!
> :information_source: See also [Let’s add a DOS door to Enigma½ BBS](https://medium.com/retro-future/lets-add-a-dos-game-to-enigma-1-2-41f257deaa3c) by Robbie Whiting for a great writeup on adding doors!
The `abracadabra` module provides a generic and flexible solution for many door types. Through this module you can execute native processes & scripts directly, and perform I/O through standard I/O (stdio) or a temporary TCP server.
| `nodeMax` | :-1: | Max number of nodes that can access this door at once. Uses `name` as a tracking key. |
| `tooManyArt` | :-1: | Art spec to display if too many instances are already in use. |
| `io` | :-1: | How to process input/output (I/O). Can be `stdio` or `socket`. When using `stdio`, I/O is handled via standard stdin/stdout. When using `socket` a temporary socket server is spawned that can be connected back to. The server listens on localhost on `{srvPort}` (See **Argument Variables** below for more information). Default value is `stdio`. |
| `encoding` | :-1: | Sets the **door's** encoding. Defaults to `cp437`. Linux binaries often produce `utf8`. |
| `{dropFilePath}` | Full path to generated dropfile. The system places dropfiles in the path set by `paths.dropFiles` in `config.hjson`. | `C:\enigma-bbs\drop\node1\DOOR.SYS` |
| `{userName}` | [Sanitized](https://www.npmjs.com/package/sanitize-filename) username. Safe for filenames, etc. If the full username is sanitized away, this will resolve to something like "user_1234". | `izard` |
[DOSEMU](http://www.dosemu.org/) can provide a good solution for running legacy DOS doors when running on Linux systems. For this, we will create a virtual serial port (COM1) that communicates via stdio.
Note that we also have the [BNU](http://www.pcmicro.com/bnu/) FOSSIL driver installed at `C:\BNU\\`. Another option would be to install this to X: somewhere as well.
Finally, let's create a `menu.hjson` entry to launch the game:
Due to Node.js limitations, ENiGMA½ does not _directly_ support `DOOR32.SYS` style socket descriptor sharing (other `DOOR32.SYS` features are fully supported). However, a separate binary called [bivrost!](https://github.com/NuSkooler/bivrost) can be used. bivrost! is available for Windows and Linux x86/i686 and x86_64/AMD64. Other platforms where [Rust](https://www.rust-lang.org/) builds are likely to work as well.
#### Example configuration
Below is an example `menu.hjson` entry using bivrost! to launch a door:
```hjson
doorWithBivrost: {
desc: Bivrost Example
module: abracadabra
config: {
name: BivrostExample
dropFileType: DOOR32
cmd: "C:\\enigma-bbs\\utils\\bivrost.exe"
args: [
"--port", "{srvPort}", // bivrost! will connect this port on localhost
"--dropfile", "{dropFilePath}", // ...and read this DOOR32.SYS produced by ENiGMA½
"--out", "C:\\doors\\jezebel", // ...and produce a NEW DOOR32.SYS here.
//
// Note that the final <target> params bivrost! will use to
// launch the door are grouped here. The {fd} variable could
Alternative workarounds include [Telnet Bridge module](telnet-bridge.md) to hook up Telnet-accessible (including local) door servers -- It may also be possible bridge via [NET2BBS](http://pcmicro.com/netfoss/guide/net2bbs.html).
[QEMU](http://wiki.qemu.org/Main_Page) provides a robust, cross platform solution for launching doors under many platforms (likely anywhere Node.js is supported and ENiGMA½ can run). Note however that there is an important and major caveat: **Multiple instances of a particular door/OS image should not be run at once!** Being more flexible means being a bit more complex. Let's look at an example for running L.O.R.D. under a UNIX like system such as Linux or FreeBSD.
Basically we'll be creating a bootstrap shell script that generates a temporary node specific `GO.BAT` to launch our door. This will be called from `AUTOEXEC.BAT` within our QEMU FreeDOS partition.
[FreeDOS](http://www.freedos.org/) is a free mostly MS-DOS compatible DOS package that works well for running 16bit doors. Follow the [QEMU/FreeDOS](https://en.wikibooks.org/wiki/QEMU/FreeDOS) guide for creating an `freedos_c.img`. This will contain FreeDOS itself and installed BBS doors.
After this is complete, copy LORD to C:\DOORS\LORD within FreeDOS. An easy way to tranfer files from host to DOS is to use QEMU's vfat as a drive. For example:
Note the `qemu-system-i386` line. We're telling QEMU to launch and use localtime for the clock, create a character device that connects to our temporary server port on localhost and map that to a serial device. The `-hdb` entry will represent the D: drive where our dropfile is generated, while `-hdc` is the path that `GO.BAT` is generated in (`E:\GO.BAT`). Finally we specify `-nographic` to run headless.
