rs-serve

A remoteStorage server implementation for POSIX systems.

Content

1. Introduction
2. Overview
   1. remoteStorage
   2. Webfinger
   3. Authorization tools
   4. Storage system
3. Installing
   1. Dependencies
   2. Getting the code
   3. Building
   4. Installing system-wide
   5. Setting options
   6. Integrating authorization

1. Introduction

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remoteStorage is an open specification for personal data storage. It is supposed to replace the currently popular proprietary "cloud storage" protocols using an open standard and thereby promoting the seperation of applications and their data on the web.

For more information, check out these links:

• http://remotestorage.io/ - Information about the remotestorage protocol and current implementations.
• http://unhosted.org/ - Philosophy, hands-on Tutorials and App collection.

2. Overview

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rs-serve brings 3 things:

• HTTP endpoint implementing remoteStorage: /storage/{user}
• HTTP endpoint implementing Webfinger: /.well-known/webfinger
• A collection of scripts to manage authorizations: add/remove/list token(s)

The user management is taken care of by the system. Each system user with an allowed user id (default: >= 1000. Minimum defined by RS_MIN_UID in src/config.h) can access their ~/storage/ directory (configurable via --dir option) using the remoteStorage endpoint.

rs-serve is written entirely in C, using mostly POSIX library functions. It relies on a few portable libraries (see the list under "Dependencies" below).

It does however currently use the signalfd() system call, which is only available on Linux. (this is a solvable problem though, if you want to be able to run on another system, please open an issue to ask for help.)

2.1) remoteStorage

The currently implemented protocol version is "draft-dejong-remotestorage-01".

Currently the following features are supported:

• CORS support for all verbs
• GET, PUT, DELETE requests on files and folders
• Opaque version strings (in directory listings and ETag header)
• Conditional GET, PUT and DELETE requests (If-Match, If-None-Match headers)
• Protection of all non-public paths via Bearer token authorization.
• Special handling of public paths (i.e. those starting with /public/), such that requests on non-directory paths succeed without authorization.
• HEAD requests on files and folders with Content-Length header (not part of remotestorage-01, only enabled when --experimental flag is given)

2.2) Webfinger

The Webfinger implementation only serves information about remoteStorage and is currently not extensible.

The hostname part of user addresses is expected to be the hostname set for the rs-serve instance. This currently defaults to local.dev and can be overridden with the --hostname option.

Virtual hosting (== hosting storage for multiple domains from a single instance) is currently not supported.

2.3) Authorization

rs-serve now comes with an authorization backend and frontend, supporting the implicit bearer flow as described by OAuth 2. Authentication happens through PAM, so you can use any authentication backend supported by PAM (such as passwd/shadow files, LDAP, SQL...).

The authorization server is written in JavaScript. To run the server-side component you need node.js. Also you need to build the bindings to the authorization tools of rs-serve.

You can do this by running:

make bindings

To start the server run

node auth/backend/server.js

It runs on port 8888 by default, you can change this by tweaking the auth/backend/server.js file. Note that you also need to configure the backend URL in auth/frontend/app.js.

The frontend part is an unhosted web app (i.e. completely client side), so you can use any webserver to serve it. However, for simplicity the backend server will also automatically serve all files from auth/frontend/.

Once you got that all running, set the --auth-uri option of rs-serve to point to where you're serving the frontend, e.g. https://example.com/?username=%s.

Note that while the remotestorage server itself needs to run on port 80, the authorization frontend and backend can run on any port you like.

2.4) Storage system

The payload data of the remotestorage endpoint is stored on the local filesystem within the respective user's home directory.

Thus a few restrictions apply:

• The remotestorage endpoint cannot be used to store both a directory and a file under the same path (ignoring the trailing slash). That means you cannot store /foo/bar/baz and /foo/bar, but only one of them. This is a natural restriction of traditional filesystems, that is currently well adhered to by all apps using remotestorage (as far as I know).

• MIME types may not be exact for files that were added "out-of-band", that is not added via the remoteStorage protocol, but by copying to the ~/storage/ directory by other means. rs-serve stores MIME type and character encoding under the user.mime_type and user.charset extended attributes, given these are supported by the underlying filesystem. When these attributes aren't set, a MIME type is guessed using libmagic, which may not always yield desirable results. (for example an empty file, created using touch will be transmitted via remoteStorage with a Content-Type header of inode/x-empty; charset=binary) If even libmagic fails to make sense of a file, the Content-Type is set to application/octet-stream; charset=binary.

3. Installing

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These steps should enable you to install rs-serve.

3.1) Dependencies

• GNU make
• cmake
• pkg-config (or tweak the Makefile)
• gcc
• libc
• libevent (>= 2.0)
• libmagic
• libattr
• BerkeleyDB

On Debian based systems, this should give you all you need:

apt-get install build-essential cmake libevent-dev libmagic-dev libattr1-dev libssl-dev libdb-dev pkg-config git

If you want to develop, you may also want debug symbols and valgrind (required by leakcheck.sh script):

apt-get install libevent-dbg valgrind

3.2) Getting the code

Given you are reading this file, you probably have the code already, but just to be sure:

Currently the rs-serve code is hosted on GitHub.

You can browse it online at https://github.com/remotestorage/rs-serve or clone it using git:

git clone git://github.com/remotestorage/rs-serve.git

3.3) Building

Given you have all dependencies installed, simply run

make

and you should be good to go.

3.4) Installing system-wide

To install the rs-serve binary to /usr/bin, run

make install

as a privileged user.

To install somewhere else, tweak the Makefile first.

This will also install an init script to /etc/init.d/rs-serve and a default configuration to /etc/default/rs-serve.

On Debian based systems (i.e. when update-rc.d is present), make install will also install the rs-serve init script into /etc/rc*.d/.

3.5) Setting options

There are a variety of options.

If you want to use the init script, you can set options in /etc/default/rs-serve, otherwise just pass them on the command line.

Run:

rs-serve --help

to get a list of supported options.

3.6) Integrating authorization

To integrate an authorization endpoint, you need to do two things:

• Configure endpoint URI

  Set the --auth-uri option to a printf style format string. %s will be replaced with the username.

• Configure your authorization endpoint to manage rs-serve tokens

  rs-serve doesn't care where tokens come from, but it need to know them to decide whether a given request is authorized or not. It maintains an internal store for authorizations (i.e. structures of [user-name, token, scopes]), which must be managed from the outside.

  The tools to do this are:

  • rs-add-token:

    Usage: rs-add-token <user> <token> <scope1> [<scope2> ... <scopeN>]
    

    • <user> is the login name of the user (rs-serve must be able to resolve it using getpwnam() in order to find the home directory)
    • <token> is the token string authenticating future requests. For rs-serve it is an opaque string.
    • <scope1>..<scopeN> are scope strings in the same form as described in draft-dejong-remotestorage-01, Section 9.

  • rs-remove-token:

    Usage: rs-remove-token <user> <token>
    

    <user> and <token> must both be given. If the token cannot be found, rs-remove-token terminates with non-zero status.

  • rs-list-tokens:

    Lists all currently installed tokens and their respective scopes.

    The output format is primarily meant for (human) debugging and subject to change.

4. Contributing

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• If you've found a bug, or have any questions, please open an issue on GitHub: https://github.com/remotestoage/rs-serve/issues

• If you want to contribute, fork the project on GitHub and send pull requests.

• In any case, don't hesitate to talk with us on IRC: #remotestorage and #unhosted, both on irc.freenode.org