support adjusting listening options

lib/floof.ex

@@ -5,14 +5,17 @@ defmodule Floof do
 
   require Logger
 
-  def accept(port) do
+  def accept(port, opts \\ []) do
     {:ok, socket} =
-      :gen_tcp.listen(port, [
-        :binary,
-        packet: 4,
-        active: false,
-        reuseaddr: true
-      ])
+      :gen_tcp.listen(
+        port,
+        [
+          :binary,
+          packet: 4,
+          active: false,
+          reuseaddr: true
+        ] ++ opts
+      )
 
     Logger.info("Accepting connections on #{port}")
     loop_acceptor(socket)

lib/floof/application.ex

@@ -8,7 +8,8 @@ defmodule Floof.Application do
 
   @impl true
   def start(_type, _args) do
-    port = Application.fetch_env!(:floof, :port)
+    listen_port = Application.fetch_env!(:floof, :listen_port)
+    listen_opts = Application.fetch_env!(:floof, :listen_opts)
     upstreams = Application.fetch_env!(:floof, :upstreams)
     markers = Application.fetch_env!(:floof, :markers)
     attrs = Application.fetch_env!(:floof, :attrs)
@@ -36,9 +37,13 @@ defmodule Floof.Application do
             pubkey_mgr: pubkey_mgr,
             pubkey_config: pubkey_config
           ), Floof.DistributorSeen}},
-        {Floof.SessionManager, %{}},
-        {Task, fn -> Floof.accept(port) end}
+        {Floof.SessionManager, %{}}
       ] ++
+        if listen_port != nil do
+          [{Task, fn -> Floof.accept(listen_port, listen_opts) end}]
+        else
+          []
+        end ++
         for upstream <- upstreams do
           {host, port} =
             case upstream do

mix.exs

@@ -20,8 +20,11 @@ defmodule Floof.MixProject do
       extra_applications: [:asn1, :logger],
       mod: {Floof.Application, []},
       env: [
-        port: 2540,
-        # upstreams have structure {host, port} or {host} (port defaults to 2540)
+        # listen_port cam be set to `nil` to disable to server-socket listener
+        listen_port: 2540,
+        # listen_opts can be used to specify e.g. `[ip: {192,168,0,133}]` a specific interface IP
+        listen_opts: [],
+        # 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