mxd

Marrakesh Express Daemon

Hop aboard the Marrakesh Express — a compact but spirited Hotline server written in Rust. It speaks just enough of the protocol for that retro BBS flair. The server uses Tokio for async networking and Diesel's async extension to keep users safely stored in SQLite. Passwords are salted and hashed with Argon2, whose knobs are adjustable via --argon2-m-cost, --argon2-t-cost, and --argon2-p-cost.

Commands arrive line by line through a BufReader. At present, only a LOGIN command is supported; invalid attempts earn an ERR reply. Each session remains open so multiple commands can be processed until the client disconnects.

Tokio keeps everything asynchronous, and this project aims to be the skeleton for a more complete Hotline implementation. See the docs/ directory for a dive into the protocol and how we juggle SQLite and PostgreSQL migrations.

If you use SQLite as the persistence engine, ensure your build of SQLite includes the JSON1 extension and support for recursive common table expressions (CTEs). The server verifies these features on startup and will fail to run if they are missing.

When using PostgreSQL, run against a server version 14 or newer. The daemon checks this at startup and refuses to launch on older versions.

mxd supports both SQLite and PostgreSQL backends. Select one at compile time using --features sqlite or --features postgres. Exactly one of these features must be enabled for a successful build. Because the sqlite feature is enabled by default, you must disable default features when opting into PostgreSQL:

cargo run --no-default-features --features postgres -- --help

The same applies to cargo build and cargo test commands targeting PostgreSQL. Note: PostgreSQL backend support is currently a work in progress.

Running

Build the project and run the daemon. Specify a bind address and database URL if the defaults don't tickle your fancy. For SQLite, use a filesystem path, while PostgreSQL requires a standard postgres:// URL. Enable the appropriate backend feature when compiling:

cargo build --features sqlite

# Run server listening on the default address
cargo run --features sqlite -- --bind 0.0.0.0:5500 --database mxd.db

# PostgreSQL example
# cargo run --no-default-features --features postgres -- --database postgres://user:pass@localhost/mxd

Creating users

Use the create-user subcommand to add accounts:

cargo run --features sqlite -- create-user alice secret

Managing migrations

Install the diesel CLI with both back-end features so you can run migrations manually when needed:

cargo install diesel_cli --no-default-features --features sqlite,postgres

Running tests

cargo test

Integration tests live in the repository's tests/ directory.

When the postgres feature is enabled, tests normally spin up an embedded PostgreSQL server. Set POSTGRES_TEST_URL to reuse an existing database URL

• Inject postgres_db into any test that needs Postgres.
• If POSTGRES_TEST_URL is set, the fixture uses that database; otherwise, it starts an embedded Postgres server.
• The public schema is dropped and recreated before each test and again on teardown, so every test runs against a pristine schema regardless of reuse.

Validation harness

The validator crate provides a compatibility check using the hx client and expectrl to ensure mxd speaks the Hotline protocol correctly. Install hx version 0.2.4 and make sure it's on your PATH before running:

cd validator
cargo test

Fuzzing

The repository includes an AFL++ harness under fuzz/. See docs/fuzzing.md for build commands, Docker usage and how the nightly GitHub Actions job integrates AFL++. Crash files are written to artifacts/main/crashes.