update connecting ip in session

lib/philomena_web/endpoint.ex

@@ -47,5 +47,6 @@ defmodule PhilomenaWeb.Endpoint do
 
   plug PhilomenaWeb.RenderTimePlug
   plug PhilomenaWeb.ReferrerPlug
+  plug PhilomenaWeb.LastIpPlug
   plug PhilomenaWeb.Router
 end

lib/philomena_web/plugs/last_ip_plug.ex

@@ -0,0 +1,24 @@
+defmodule PhilomenaWeb.LastIpPlug do
+  @moduledoc """
+  This plug stores the connecting IP address in the session.
+  ## Example
+
+      plug PhilomenaWeb.LastIpPlug
+  """
+
+  alias Plug.Conn
+
+  @doc false
+  @spec init(any()) :: any()
+  def init(opts), do: opts
+
+  @doc false
+  @spec call(Conn.t(), any()) :: Conn.t()
+  def call(conn, _opts) do
+    {:ok, ip} = EctoNetwork.INET.cast(conn.remote_ip)
+
+    conn
+    |> Conn.fetch_session()
+    |> Conn.put_session(:remote_ip, to_string(ip))
+  end
+end