add support for automatic connection to upstream hosts

lib/floof.ex

@@ -27,6 +27,16 @@ defmodule Floof do
     loop_acceptor(socket)
   end
 
+  def connect(host, port) do
+    {:ok, socket} = :gen_tcp.connect(host, port, [
+      packet: 4,
+      active: true
+    ])
+    send(Floof.Distributor, {:register, self()})
+    Logger.info("Established connection to #{host}:#{port}")
+    serve(socket, %{})
+  end
+
   defp serve(client, backlog) do
     receive do
       {:tcp, _, message} ->

lib/floof/application.ex

@@ -9,6 +9,7 @@ defmodule Floof.Application do
   @impl true
   def start(_type, _args) do
     port        = Application.fetch_env!(:floof, :port)
+    upstreams   = Application.fetch_env!(:floof, :upstreams)
     markers     = Application.fetch_env!(:floof, :markers)
     attrs       = Application.fetch_env!(:floof, :attrs)
     set_markers = Application.fetch_env!(:floof, :set_markers)
@@ -23,7 +24,14 @@ defmodule Floof.Application do
       )},
       {Floof.SessionManager, %{}},
       {Task, fn -> Floof.accept(port) end},
-    ]
+    ] ++ (for upstream <- upstreams do
+      {host, port} = case upstream do
+        {host, port} -> {host, port}
+        {host} -> {host, 2540}
+      end
+      # this establishes connections to upstream hosts
+      {Task, fn -> Floof.connect(host, port) end}
+    end)
 
     # See https://hexdocs.pm/elixir/Supervisor.html
     # for other strategies and supported options

mix.exs

@@ -20,6 +20,8 @@ defmodule Floof.MixProject do
       mod: {Floof.Application, []},
       env: [
         port: 2540,
+        # upstreams have structure {host, port} or {host} (port defaults to 2540)
+        upstreams: [],
         # markers have the structure {bool(), {:RelativeDistinguishedName, oid-as-list(), value()}}
         # all of the markers marked with 'true' should be included in each message to-be-processed
         # and none of the markers marked with 'false' should be included. the same holds for attrs.