Ryan-Myers/decomp.me

Crowdsourced decompilation platform

decomp.me

A collaborative decompilation and reverse engineering website, built with Next.js and Django.

Directory structure

frontend/
  public/        ; Static files
  src/           ; React/Typescript sourcecode

backend/
  compilers/     ; Compiler binaries and configuration
  coreapp/       ; API Django app
    migrations/  ; Database migrations (generated by Django)
  decompme/      ; Main Django app

.env             ; Default configuration
.env.local       ; Local configuration overrides (not checked-in)

Setup

See DOCKER.md for instructions on how to run the project in a Docker container.

Dependencies:

• Python >=3.8
• Node.js
• Yarn

---

• Create a file to hold environment variables:

touch .env.local

Frontend

cd frontend

• Install dependencies

yarn

• Start the development webserver

yarn dev

• Access the site via http://localhost:8080

Backend

cd backend

• Set up a virtual environment (optional)

python3 -m virtualenv venv
source venv/bin/activate

• Install dependencies

pip install -r requirements.txt
./compilers/download.sh

• Set up the database

python manage.py migrate

• Start the API server

python manage.py runserver

---

The following setup sections are optional.

Wine setup (for local development, running Windows compilers)

• Create a wineprefix dir

WINEPREFIX=$HOME/.wine WINEARCH=win32 wineboot --init

• Add the WINEPREFIX setting to your .local.env file in the root of the repo

echo "WINEPREFIX=$HOME/.wine" >> .local.env

GitHub authentication

• Register a new OAuth application

  • "Homepage URL" should be the URL you access the frontend on (e.g. http://localhost:8080)
  • "Authorization callback URL" should be the same as the homepage URL, but with /login appended

• Edit .env.local:

  • Set GITHUB_CLIENT_ID to the application client ID
  • Set GITHUB_CLIENT_SECRET to the application client secret (do not share this)

Running inside an nginx proxy

Running decomp.me using nginx as a proxy better emulates the production environment and can avoid cookie-related issues.

• Install nginx

• Create an nginx site configuration (typically /etc/nginx/sites-available/local.decomp.me)

server {
    listen 80;
    listen [::]:80;
    client_max_body_size 5M;

    server_name local.decomp.me www.local.decomp.me;

    location / {
        try_files $uri @proxy_frontend;
    }

    location /api {
        try_files $uri @proxy_api;
    }
    location /admin {
        try_files $uri @proxy_api;
    }
    location /static {
        try_files $uri @proxy_api;
    }

    location @proxy_api {
        proxy_set_header X-Forwarded-Proto https;
        proxy_set_header X-Url-Scheme $scheme;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        proxy_pass http://127.0.0.1:8000;
    }

    location @proxy_frontend {
        proxy_set_header X-Forwarded-Proto https;
        proxy_set_header X-Url-Scheme $scheme;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        proxy_pass http://127.0.0.1:8080;
    }
}

• Enable the site

ln -s /etc/nginx/sites-available/local.decomp.me /etc/nginx/sites-enabled/local.decomp.me

• Add the following lines to /etc/hosts:

127.0.0.1	    local.decomp.me
127.0.0.1	    www.local.decomp.me

• Edit .env.local:

  • Set API_BASE=/api
  • Set ALLOWED_HOSTS=local.decomp.me

• If you set up GitHub authentication, change the application URLs to http://local.decomp.me and http://local.decomp.me/login

• Restart nginx, the frontend, and the backend

• Access the site via http://local.decomp.me

Sandbox jail

There is support for running subprocesses within nsjail.

This is controlled by the SANDBOX settings, and is disabled by default in the development .env but is enabled inside the backend Docker container.

To enable it locally outside of the Docker container:

• Build or install nsjail locally. Example instructions for Ubuntu:

  • apt-get install autoconf bison flex gcc g++ git libprotobuf-dev libnl-route-3-dev libtool make pkg-config protobuf-compiler
  • git clone --recursive --branch=3.0 https://github.com/google/nsjail
  • cd nsjail && make

• Enable unprivileged_userns_clone

  • Temporary: sudo sysctl -w kernel.unprivileged_userns_clone=1
  • Permanent: echo 'kernel.unprivileged_userns_clone=1' | sudo tee -a /etc/sysctl.d/00-local-userns.conf && sudo service procps restart

• Edit .env.local:

  • Set USE_SANDBOX_JAIL=on
  • Set SANDBOX_NSJAIL_BIN_PATH to the absolute path of the nsjail binary built above

Deployment

• Backend - same as in development, just set DEBUG=true
• Frontend - multiple options:
  • Self-hosted - yarn build && yarn start with nginx proxy to filter /api/* to the backend
  • Deploy with Vercel

Contributing

Contributions are very much welcome! You may want to join our Discord server.

Storybook

Use yarn storybook to run a Storybook instance on http://localhost:6006. This is useful for testing UI components in isolation.

Linting

• Check frontend

cd frontend
yarn lint

• Autofix frontend

cd frontend
yarn lint --fix

• Check backend

cd backend
mypy

Updating the database

If you modify any database models (models.py), you'll need to run the following to update the database:

python manage.py makemigrations
python manage.py migrate

License

decomp.me uses the MIT license. All dependencies may contain their own licenses, which decomp.me respects.