Architex

A Matrix homeserver written in Elixir. Currently, this project is in a very early stage.

General architecture

For each room that a homeserver is involved in, there is a supervised GenServer (named RoomServer) that holds/manages the room's state. These RoomServers are responsible for state resolution and authorization. Database schemas are located at lib/architex/schema/. Requests from the federation API as well as the client API are validated using Ecto's embedded_schemas, located at lib/architex_web/api_schemas/.

Noteworthy contributions

• lib/architex/state_resolution.ex: Implementation of version 2 of the Matrix state resolution algorithm.
• lib/architex/state_resolution/authorization.ex: Implementation of authorization rules for the state resolution algorithm.
• lib/architex/room_server.ex: A GenServer that holds and manages the state of a room.

Dependencies

• Elixir 1.12.2 compiled for OTP 24
• Erlang 24.0.3
• PostgreSQL
• Libsodium

Generate the server's ed25519 keys by executing ssh-keygen -t ed25519 -f keys/id_ed25519 -N ""

Progress

Here, implemented and some unimplemented features are listed.

Implemented features

• State resolution: functional, but very memory-intensive and with high database usage. For now it is sufficient, but snapshots should be used in the future. See: State Resolution v2 for the Hopelessly Unmathematical, State Resolution: Reloaded and Room Version 2.
• Authorization rules (Room version 1)
• Homeserver authentication using signing keys (4.1 Request Authentication)
• Client authentication (5.1 Using access tokens)

Implemented API endpoints

Client-Server API

• GET /_matrix/client/r0/register/available
• GET /_matrix/client/r0/account/whoami
• POST /_matrix/client/r0/logout
• POST /_matrix/client/r0/logout/all
• PUT /_matrix/client/r0/directory/room/{roomAlias}
• GET /_matrix/client/versions
• GET /_matrix/client/r0/login
• POST /_matrix/client/r0/login: Only with password flow.
• POST /_matrix/client/r0/register: Only with dummy flow.
• POST /_matrix/client/r0/createRoom: Except with option invite_3pid.
• GET /_matrix/client/r0/joined_rooms
• POST /_matrix/client/r0/rooms/{roomId}/invite
• POST /_matrix/client/r0/rooms/{roomId}/join: Except with third party invite.
• POST /_matrix/client/r0/rooms/{roomId}/leave
• POST /_matrix/client/r0/rooms/{roomId}/kick
• POST /_matrix/client/r0/rooms/{roomId}/ban
• POST /_matrix/client/r0/rooms/{roomId}/unban
• PUT /_matrix/client/r0/rooms/{roomId}/state/{eventType}/{stateKey}
• PUT /_matrix/client/r0/rooms/{roomId}/send/{eventType}/{txnId}
• GET /_matrix/client/r0/rooms/{roomId}/messages: Except filtering.
• GET /_matrix/client/r0/directory/list/room/{roomId}
• PUT /_matrix/client/r0/directory/list/room/{roomId}
• GET /_matrix/client/r0/capabilities
• GET /_matrix/client/r0/profile/{userId}
• GET /_matrix/client/r0/profile/{userId}/avatar_url
• PUT /_matrix/client/r0/profile/{userId}/avatar_url
• GET /_matrix/client/r0/profile/{userId}/displayname
• PUT /_matrix/client/r0/profile/{userId}/displayname

Federation API

• GET /_matrix/federation/v1/event/{eventId}
• GET /_matrix/federation/v1/state/{roomId}
• GET /_matrix/federation/v1/state_ids/{roomId}
• GET /_matrix/key/v2/server/{keyId}
• GET /_matrix/federation/v1/query/profile: Except displayname and avatar_url is not implemented.

Major unimplemented features

• Resolving server names (but works for local development) (3.1 Resolving server names)
• Checks when receiving events via federation (i.e. valid format, signature check and hash check) (6.1 Checks performed on receipt of a PDU)
• Federation of events