walnut

An opinionated, constrained, secure application framework with a hard shell - kinda like iOS, but for a server.

Applications are written in express, but instead of using require for generic packages, they use req.getSiteCapability(pkg) and are restricted to packages that have been allowed by app, device, site, or user permission. Any configuration for the capability (external passwords, api keys, etc) will be set up beforehand so that they are not exposed to the application.

Security Features

• JSON-only APIs
• JWT (not cookie*) authentication
• no server-rendered html
• disallows urlencoded forms, except for secured webhooks
• disallows cookies, except for protected static assets
• api.* subdomain for apis
• assets.* subdomain for protected assets
• must sit behind a trusted https proxy (such as Goldilocks)
• HTTPS-only (checks for X-Forwarded-For)
• AES, RSA, and ECDSA encryption and signing
• Safe against CSRF, XSS, and SQL injection
• Safe against Compression attacks

*Cookies are used only for GETs and only where using a token would be less secure - such as images which would otherwise require the token to be passed into the img src. They are also scoped such that CSRF attacks are not possible.

Application Features

• JSON-only expressjs APIs
• Capability-based permissions system for (oauth3-discoverable) packages such as
  • large file access (files@daplie.com)
  • database access (data@daplie.com)
  • scheduling (for background tasks, alerts, alarms, calendars, reminders, etc) (events@daplie.com)
  • payments (credit card) (payments@daplie.com)
  • email (email@daplie.com)
  • SMS (texting) (tel@daplie.com)
  • voice (calls and answering machine) (tel@daplie.com)
  • lamba-style functions (functions@daplie.com)
• Per-app, per-site, and per-user configurations
• Multi-Tentated Application Management
• Built-in OAuth2 & OAuth3 support

Currently being tested with Ubuntu, Raspbian, and Debian on Digital Ocean, Raspberry Pi, and Heroku.

Installation

We're still in a stage where the installation generally requires many manual steps.

See INSTALL.md

Usage

Here's how you run the thing, once installed:

/opt/walnut/bin/node /srv/walnut/core/bin/walnut.js

It listens on all addresses, port 3000.

TODO: Add config to restrict listening to localhost.

API

The API is still in flux, but you can take a peek anyway.

See API.md

Understanding Walnut

/srv/walnut/
├── setup.sh (in-progress)
├── core
│   ├── bin
│   ├── boot
│   └── lib
├── etc
│   └── client-api-grants
├── node_modules
├── packages
│   ├── apis
│   ├── pages
│   ├── rest
│   └── services
└── var
    └── sites

• core contains all walnut code
• node_modules is a flat installation of all dependencies
• certs is a directory for Let's Encrypt (or custom) certificates
• var is a directory for database files and such
• packages contains 3 types of packages

Will install to

/srv/walnut/core/
/etc/walnut
/opt/walnut
/var/log/walnut
/etc/systemd/system/walnut.service
/etc/tmpfiles.d/walnut.conf

Initialization

needs to know its primary domain

POST https://api.<domain.tld>/api/walnut@daplie.com/init

{ "domain": "<domain.tld>" }

The following domains are required to point to WALNUT server

cloud.<domain.tld>
api.cloud.<domain.tld>

and

<domain.tld>
www.<domain.tld>

api.<domain.tld>
assets.<domain.tld>

The domains can be setup through the Daplie Desktop App or with daplie-tools

# set device address and attach primary domain
daplie devices:attach -d foodevice -n example.com -a 127.0.0.1

# attach all other domains with same device/address
daplie devices:attach -d foodevice -n www.example.com
daplie devices:attach -d foodevice -n api.example.com
daplie devices:attach -d foodevice -n assets.example.com
daplie devices:attach -d foodevice -n cloud.example.com
daplie devices:attach -d foodevice -n api.cloud.example.com

Example /etc/goldilocks/goldilocks.yml:

tls:
  email: domains@example.com
  servernames:
    - example.com
    - www.example.com
    - api.example.com
    - assets.example.com
    - cloud.example.com
    - api.cloud.example.com

http:
  trust_proxy: true
  modules:
    - name: proxy
      domains:
        - '*'
      address: '127.0.0.1:3000'

Resetting the Initialization

Once you run the app the initialization files will appear in these locations

/srv/walnut/var/walnut+config@daplie.com.sqlite3
/srv/walnut/config/<domain.tld>/config.json

Deleting those files and restarting walnut will reset it to its bootstrap state.

Accessing static apps

Static apps are stored in packages/pages

# App ID as files with a list of packages they should load
# note that '#' is used in place of '/' because files and folders may not contain '/' in their names
/srv/walnut/packages/pages/<domain.tld#path>          # https://domain.tld/path
/srv/walnut/packages/pages/<domain.tld>               # https://domain.tld and https://domain.tld/foo match

# packages are directories with email-style name      # For the sake of debugging these packages can be accessed directly, without a site by
/srv/walnut/packages/pages/<package@domain.tld>       # matches apps.<domain.tld>/<package-name> and <domain.tld>/apps/<package-name>

Accessing REST APIs

# Apps are granted access to use a package by listing it in the grants file by the name of the app url (domain.tld)
/srv/walnut/packages/client-api-grants/<domain.tld>   # matches api.<domain.tld>/api/ and contains a list of allowed REST APIs
                                                      # the REST apis themselves are submatched as api.<domain.tld>/api/<tld.domain.package>

# packages are directories with reverse dns name, a package.json, and an index.js
/srv/walnut/packages/rest/<tld.domain.package>

Example tree with contents:

Here com.example.hello is a package with a REST API and a static page and foobar.me is a WALNUT-configured domain (smithfam.net, etc).

The packages:

/srv/walnut/packages/
├── api
├── rest
│   └── com.example.hello
│      ├── package.json
│      └── index.js
│           '''
│           'use strict';
│
│           module.exports.create = function (conf, deps, app) {
│
│             app.use('/', function (req, res) {
│               console.log('[com.example.hello] req.url', req.url);
│               res.send({ message: 'hello' });
│             });
│
│             return deps.Promise.resolve();
│           };
│
│           '''
│
└── services

/srv/walnut/packages/
└── pages
    └── demo@example.com
        └── index.html
              '''
              <html>
                <head><title>demo@example.com</title></head>
                <body>
                  <h1>demo@example.com</h1>
                </body>
              </html>
              '''

The permissions:

/srv/walnut/packages/
└── client-api-grants
    └── cloud.foobar.me
          '''
          hello@example.com     # refers to /srv/walnut/packages/rest/hello@example.com
          '''

/srv/walnut/var/
└── sites
    └── daplie.me
          '''
          seed@example.com      # refers to /srv/walnut/packages/pages/seed@example.com
          '''