dummy impl lmao lol funny commit message xD

lib/p2p_chat/transport_proto.ex

@@ -0,0 +1,67 @@
+defmodule P2pChat.TransportProto do
+  defmodule Messages do
+    defmodule Hello do
+      defstruct [:netid]
+    end
+    
+    defmodule InformNeighbor do
+      defstruct [:netid, :addr, :port]
+    end
+
+    defmodule Goodbye do
+      defstruct []
+    end
+  end
+
+  #
+  # Public API
+  # 
+
+  def encode_message(%Messages.Hello{} = msg) do
+    [encode_version(), <<0x01::8>>, encode_string(msg.netid)]
+  end
+  
+  def encode_message(%Messages.InformNeighbor{} = msg) do
+    [encode_version(), <<0x02::8>>, encode_string(msg.netid), encode_ip_addr(msg.addr)]
+  end
+
+  def encode_message(%Messages.Goodbye{} = _msg) do
+    [encode_version(), <<0x03::8>>]
+  end
+
+  def decode_message(<<0x01::8, 0x01::8, payload::binary>>) do
+    <<netid_len::16, netid::size(netid_len)-binary>> = payload
+    %Messages.Hello{netid: netid}
+  end
+
+  def decode_message(<<0x01::8, 0x02::8, payload::binary>>) do
+    <<netid_len::16, netid::size(netid_len)-binary, addr_len::16, addr::size(addr_len)-binary>> = payload
+    %Messages.InformNeighbor{netid: netid, addr: addr}
+  end
+
+  def decode_message(<<0x01::8, 0x03::8>>) do
+    %Messages.Goodbye{}
+  end
+
+  def decode_message(<<0x01::8, _::binary>>), do: :error
+  def decode_message(<<_::binary>>), do: :error
+
+  #
+  # Private Utilities
+  # 
+
+  defp encode_version() do
+    <<0x01::8>>
+  end
+
+  defp encode_string(str) do
+    [<<byte_size(str)::16>>, str]
+  end
+
+  defp encode_ip_addr({a1, a2, a3, a4, a5, a6, a7, a8}) do
+    <<6::8, a1::8, a2::8, a3::8, a4::8, a5::8, a6::8, a7::8, a8::8>>
+  end
+  defp encode_ip_addr({a1, a2, a3, a4}) do
+    <<4::8, a1::8, a2::8, a3::8, a4::8>>
+  end
+end