M(y)FTP is a simple file-transfer and file system manipulation protocol, very similar, but completely incompatible with FTP. It's basically passive-mode-only FTP with changes to command and response format.

I've created this protocol for educational purposes - to learn about event-driven network programming and low-level asynchronous I/O in C.

Protocol itself is described here.

I've decided, that I hate myself enough to implement this protocol in C. I've used libuev for event loop. The rest is just plain C-99 with some POSIX functions.

WARNING: This library user posix functions and libuev - both are incompatible with Windows. This code WON'T work on Windows.

For now, only server is implemented. I use telnet as a simple test client.

I've used pre-compiled version of libuev just because I can't be bothered with integrating their automake project with my cmake project, and I refuse to learn plain makefiles.

Making sure all things work on all Linux distributions and Windows is out of scope of this project - I barely manage to write any working code for my own machine. I use Ubuntu 24 (systemd, bash) - it works here.

As mentioned before, only POSIX systems are supported (tested only on Ubuntu 24, so not sure about anything else).

Intended building process uses cmake - any modern version should work. Of course, you'll also need a C-99 compiler and some build-system (like make).

Run:

cmake -S . -B build

To generate build files. Then:

cmake --build build

To build the project.

This should generate mftp-server binary in build directory. There should also be mftp-client-cli binary there - you can use it to dump some file to TCP connection - I use it to test STOR command.

WARNING - Basic installation target assumes you have both systemd and bash in your system. If you don't, you'll have to install server manually (for now).

There is basic installation target available in cmake:

sudo cmake --install build

To install mftp-server binary to /usr/local/bin directory, create mftp group and user, set-up systemd service and directories for server files.

To check if server is running, you can use:

systemctl status mftp

Alternatively, you can "install" server manually. Server expects /srv/mftp directory to be present and writeable by user running server binary - this is baked into the code.

Inside of it, during first run, server will create .ini configuration file you can use to configure server (like port, root directory, etc.).

To uninstall server, you can use:

sudo cmake --build build --target uninstall

Alternatively, at this point, there are only three files and a directory created by installation process:

• /usr/local/bin/mftp-server - server binary
• /usr/local/bin/mftp-setup.bash - script to create mftp user and group, and set up directories
• /etc/systemd/system/mftp.service - systemd service file
• /srv/mftp - directory for server files

You can remove them manually. Also, remember to remove mftp user and group and reload systemd daemons.

At this point, only basic features of server are implemented. There are many things to do:

• Implement basic server commands
• Memory management is a mess (server leaks on sigint/sigterm) - whole server::ctx needs a rewrite.
• Implement loading server configuration from file
• Some kind of client with GUI
• Windows support (maybe)

• I use linked list for all dynamic arrays - it's not the best solution
• Libuev is not portable - I want this app to also work on OS for games...

License for this project is available in LICENSE file.

This project uses pre-compiled libuev library, as well as its, very slightly modified by me, header files. See libuev license for more information.