Add forward extremities to rooms

lib/matrix_server/event.ex

@@ -106,4 +106,20 @@ defmodule MatrixServer.Event do
   def generate_event_id do
     "$" <> MatrixServer.random_string(17) <> ":" <> MatrixServer.server_name()
   end
+
+  def is_control_event(%Event{type: "m.room.power_levels", state_key: ""}), do: true
+  def is_control_event(%Event{type: "m.room.join_rules", state_key: ""}), do: true
+
+  def is_control_event(%Event{
+        type: "m.room.member",
+        state_key: state_key,
+        sender: sender,
+        content: %{membership: membership}
+      })
+      when sender != state_key and membership in ["leave", "ban"],
+      do: true
+
+  def is_control_event(_), do: false
+
+  def is_state_event(%Event{state_key: state_key}), do: state_key != nil
 end

lib/matrix_server/room.ex

@@ -2,13 +2,15 @@ defmodule MatrixServer.Room do
   use Ecto.Schema
 
   import Ecto.Changeset
+  import Ecto.Query
 
-  alias MatrixServer.{Room, Event}
+  alias MatrixServer.{Repo, Room, Event}
   alias MatrixServerWeb.API.CreateRoom
 
   @primary_key {:id, :string, []}
   schema "rooms" do
     field :visibility, Ecto.Enum, values: [:public, :private]
+    field :forward_extremities, {:array, :string}
     has_many :events, Event, foreign_key: :event_id
   end
 
@@ -27,4 +29,23 @@ defmodule MatrixServer.Room do
   def generate_room_id do
     "!" <> MatrixServer.random_string(18) <> "@" <> MatrixServer.server_name()
   end
+
+  def update_forward_extremities(%Event{
+        event_id: event_id,
+        prev_events: prev_event_ids,
+        room_id: room_id
+      }) do
+    %Room{forward_extremities: forward_extremities} =
+      Room
+      |> where([r], r.id == ^room_id)
+      |> Repo.one!()
+
+    new_forward_extremities = [event_id | forward_extremities -- prev_event_ids]
+
+    {_, [room | _]} =
+      from(r in Room, where: r.id == ^room_id, select: r)
+      |> Repo.update_all(set: [forward_extremities: new_forward_extremities])
+
+    room
+  end
 end

lib/matrix_server/room_server.ex

@@ -1,6 +1,8 @@
 defmodule MatrixServer.RoomServer do
   use GenServer
 
+  import Ecto.Query
+
   alias MatrixServer.{Repo, Room, Event, Account, StateResolution}
   alias MatrixServerWeb.API.CreateRoom
 
@@ -45,13 +47,12 @@ defmodule MatrixServer.RoomServer do
        ) do
     create_room_event = Event.create_room(room_id, MatrixServer.get_mxid(localpart), room_version)
 
-    verify_event(create_room_event)
-    |> IO.inspect()
+    verify_and_insert_event(create_room_event)
 
     {:ok, %{}}
   end
 
-  defp verify_event(event) do
+  defp verify_and_insert_event(event) do
     # Check the following things:
     # 1. TODO: Is a valid event, otherwise it is dropped.
     # 2. TODO: Passes signature checks, otherwise it is dropped.
@@ -61,9 +62,22 @@ defmodule MatrixServer.RoomServer do
     # 6. TODO: Passes authorization rules based on the current state of the room, otherwise it is "soft failed".
     if StateResolution.is_authorized_by_auth_events(event) do
       state_set = StateResolution.resolve(event, false)
-      StateResolution.is_authorized(event, state_set)
+
+      if StateResolution.is_authorized(event, state_set) do
+        # TODO: Assume the event is a forward extremity, should check this actually.
+        Room.update_forward_extremities(event)
+        {:ok, event} = Repo.insert(event)
+        {:ok, state_set}
       else
-      false
+        {:error, :rejected}
       end
+    else
+      {:error, :rejected}
+    end
+  end
+
+  def testing do
+    account = Repo.one!(from a in Account, limit: 1)
+    create_room(%CreateRoom{}, account)
   end
 end

lib/matrix_server/state_resolution.ex

@@ -3,15 +3,6 @@ defmodule MatrixServer.StateResolution do
 
   alias MatrixServer.{Repo, Event}
 
-  def example do
-    %Event{content: content} = event = Event.power_levels("room1", "charlie")
-    event = %Event{event | content: %{content | "ban" => 0}}
-
-    event
-    |> Map.put(:prev_events, ["b", "fork"])
-    |> Map.put(:auth_events, ["create", "join_charlie", "b"])
-  end
-
   def resolve(%Event{room_id: room_id} = event, apply_state) do
     room_events =
       Event
@@ -34,8 +25,8 @@ defmodule MatrixServer.StateResolution do
       |> Enum.map(&resolve(&1, room_events, apply_state))
 
     resolved_state = do_resolve(state_sets, room_events)
-    # TODO: check if state event
-    if apply_state do
+
+    if apply_state and Event.is_state_event(event) do
       Map.put(resolved_state, {type, state_key}, event)
     else
       resolved_state
@@ -55,13 +46,12 @@ defmodule MatrixServer.StateResolution do
   end
 
   def do_resolve(state_sets, room_events, unconflicted_state_map, conflicted_state_set) do
-    # TODO: make the state set a hashmap instead of a set.
     full_conflicted_set =
       MapSet.union(conflicted_state_set, auth_difference(state_sets, room_events))
 
     conflicted_control_event_ids =
       full_conflicted_set
-      |> Enum.filter(&is_control_event(&1, room_events))
+      |> Enum.filter(&Event.is_control_event(room_events[&1]))
       |> MapSet.new()
 
     conflicted_control_events_with_auth_ids =
@@ -125,7 +115,6 @@ defmodule MatrixServer.StateResolution do
   end
 
   def auth_difference(state_sets, room_events) do
-    # TODO: memoization possible
     full_auth_chains =
       Enum.map(state_sets, fn state_set ->
         state_set
@@ -146,7 +135,6 @@ defmodule MatrixServer.StateResolution do
   end
 
   def auth_chain(%Event{auth_events: auth_events}, room_events) do
-    # TODO: handle when auth event is not found.
     auth_events
     |> Enum.map(&room_events[&1])
     |> Enum.reduce(MapSet.new(), fn %Event{event_id: auth_event_id} = auth_event, acc ->
@@ -157,22 +145,6 @@ defmodule MatrixServer.StateResolution do
     end)
   end
 
-  def is_control_event(event_id, room_events), do: is_control_event(room_events[event_id])
-
-  def is_control_event(%Event{type: "m.room.power_levels", state_key: ""}), do: true
-  def is_control_event(%Event{type: "m.room.join_rules", state_key: ""}), do: true
-
-  def is_control_event(%Event{
-        type: "m.room.member",
-        state_key: state_key,
-        sender: sender,
-        content: %{membership: membership}
-      })
-      when sender != state_key and membership in ["leave", "ban"],
-      do: true
-
-  def is_control_event(_), do: false
-
   def rev_top_pow_order(room_events) do
     fn %Event{origin_server_ts: timestamp1, event_id: event_id1} = event1,
        %Event{origin_server_ts: timestamp2, event_id: event_id2} = event2 ->
@@ -349,4 +321,13 @@ defmodule MatrixServer.StateResolution do
 
     is_authorized(event, state_set)
   end
+
+  def testing do
+    %Event{content: content} = event = Event.power_levels("room1", "charlie")
+    event = %Event{event | content: %{content | "ban" => 0}}
+
+    event
+    |> Map.put(:prev_events, ["b", "fork"])
+    |> Map.put(:auth_events, ["create", "join_charlie", "b"])
+  end
 end

priv/repo/migrations/20210725121639_add_forward_extremities_to_rooms.exs

@@ -0,0 +1,9 @@
+defmodule MatrixServer.Repo.Migrations.AddForwardExtremitiesToRooms do
+  use Ecto.Migration
+
+  def change do
+    alter table(:rooms) do
+      add :forward_extremities, {:array, :string}, default: [], null: false
+    end
+  end
+end