Add federation API

Add signing keys fed API request

lib/matrix_server.ex

@@ -33,7 +33,7 @@ defmodule MatrixServer do
   def default_room_version, do: "7"
 
   def get_domain(id) do
-    case String.split(id, ":") do
+    case String.split(id, ":", parts: 2) do
       [_, server_name] -> server_name
       _ -> nil
     end

lib/matrix_server/account.ex

@@ -102,7 +102,7 @@ defmodule MatrixServer.Account do
   end
 
   defp try_get_localpart("@" <> rest = user_id) do
-    case String.split(rest, ":") do
+    case String.split(rest, ":", parts: 2) do
       [localpart, _] -> localpart
       _ -> user_id
     end

lib/matrix_server/application.ex

@@ -13,7 +13,8 @@ defmodule MatrixServer.Application do
       MatrixServerWeb.Endpoint,
       {Registry, keys: :unique, name: MatrixServer.RoomServer.Registry},
       {DynamicSupervisor, name: MatrixServer.RoomServer.Supervisor, strategy: :one_for_one},
-      MatrixServer.SigningServer
+      MatrixServer.SigningServer,
+      {Finch, name: MatrixServerWeb.HTTPClient}
     ]
 
     Supervisor.start_link(children, name: MatrixServer.Supervisor, strategy: :one_for_one)

lib/matrix_server_web/federation_client.ex

@@ -0,0 +1,23 @@
+defmodule MatrixServerWeb.FederationClient do
+  use Tesla
+
+  alias MatrixServerWeb.Endpoint
+  alias MatrixServerWeb.Router.Helpers, as: RouteHelpers
+
+  # TODO: Maybe create database-backed homeserver struct to pass to client function.
+
+  @middleware [
+    {Tesla.Middleware.Headers, [{"Content-Type", "application/json"}]},
+    Tesla.Middleware.JSON
+  ]
+
+  @adapter {Tesla.Adapter.Finch, name: MatrixServerWeb.HTTPClient}
+
+  def client(server_name) do
+    Tesla.client([{Tesla.Middleware.BaseUrl, server_name} | @middleware], @adapter)
+  end
+
+  def get_signing_keys(client) do
+    Tesla.get(client, RouteHelpers.key_path(Endpoint, :get_signing_keys))
+  end
+end