Add support for ranch_tcp opts: ip, ipv6_v6only, inet, inet6

lib/grpc/server/adapters/cowboy.ex

@@ -221,7 +221,22 @@ defmodule GRPC.Server.Adapters.Cowboy do
 
   defp socket_opts(port, opts) do
     socket_opts = [port: port]
-    socket_opts = if opts[:ip], do: [{:ip, opts[:ip]} | socket_opts], else: socket_opts
+
+    # https://ninenines.eu/docs/en/ranch/1.7/manual/ranch_tcp/
+    allowed_ranch_opts = %{
+      ip: {:ip, opts[:ip]},
+      ipv6_v6only: {:ipv6_v6only, opts[:ipv6_v6only]},
+      net: opts[:net]
+    }
+
+    socket_opts =
+      Enum.reduce(allowed_ranch_opts, socket_opts, fn {key, value}, acc ->
+        if opts[key] != nil do
+          [value | acc]
+        else
+          acc
+        end
+      end)
 
     if opts[:cred] do
       opts[:cred].ssl ++

test/grpc/server/adapters/cowboy_test.exs

@@ -0,0 +1,49 @@
+defmodule GRPC.Server.Adapters.CowboyTest do
+  use ExUnit.Case, async: false
+
+  alias GRPC.Server.Adapters.Cowboy
+
+  describe "child_spec/4" do
+    test "produces the correct socket opts for ranch_tcp for inet" do
+      spec =
+        Cowboy.child_spec(:endpoint, [], 8080, [
+          {:foo, :bar},
+          {:ip, {127, 0, 0, 1}},
+          {:ipv6_v6only, false},
+          {:net, :inet},
+          {:baz, :foo}
+        ])
+
+      socket_opts = get_socket_opts_from_child_spec(spec)
+      assert socket_opts == [:inet, {:ipv6_v6only, false}, {:ip, {127, 0, 0, 1}}, {:port, 8080}]
+    end
+
+    test "produces the correct socket opts for ranch_tcp for inet6" do
+      spec =
+        Cowboy.child_spec(:endpoint, [], 8081, [
+          {:foo, :bar},
+          {:ip, {0, 0, 0, 0, 0, 0, 0, 1}},
+          {:ipv6_v6only, true},
+          {:net, :inet6},
+          {:baz, :foo}
+        ])
+
+      socket_opts = get_socket_opts_from_child_spec(spec)
+
+      assert socket_opts == [
+               :inet6,
+               {:ipv6_v6only, true},
+               {:ip, {0, 0, 0, 0, 0, 0, 0, 1}},
+               {:port, 8081}
+             ]
+    end
+  end
+
+  defp get_socket_opts_from_child_spec(spec) do
+    {_Cowboy, _start_link, start_opts} = spec.start
+    [_http, _endpoint, _empty_list, ranch_listener_call] = start_opts
+    {_ranch_listener_sup, _start_link, ranch_listener_opts} = ranch_listener_call
+    [_endpoint, _ranch_tcp, transport_opts, _cowboy_clear, _opts_map] = ranch_listener_opts
+    transport_opts.socket_opts
+  end
+end