GenRaw

An Elixir GenServer for using raw packet sockets.

This module is largely a demo of Michael Santos's excellent procket library for Erlang. It really just encodes my knowledge about how to use procket, but perhaps someone else will find it valuable.

N.B.: Using procket with Erlang ports is broken in OTP 21.0. However, this was fixed in OTP 21.1.

Documentation is available at https://jonnystorm.gitlab.io/genraw-elixir.

Usage

iex> {:ok, pid} = GenRaw.start_link
{:ok, #PID<0.123.0>}
iex> GenRaw.open(pid)
:ok
iex> GenRaw.receive(pid)
{:error, :eagain}
iex> {:ok, data} = GenRaw.receive(pid)
{ :ok,
  <<255, 255, 255, 255, 255, 255,
    192, 255, 51, 192, 255, 51,
    0, 4,
    116, 101, 115, 116
  >>
}
iex> GenRaw.receive_parsed(pid)
{ :ok, [
    dix: %{
      dst: <<255, 255, 255, 255, 255, 255>>,
      src: <<192, 255, 51, 192, 255, 51>>,
      type: 4,
    },
    data: "test",
  ]
}
iex> GenRaw.send(pid, data)
:ok

Installation

In your mix.exs, simply add

def deps do
  [ { :gen_raw_ex,
      git: "https://gitlab.com/jonnystorm/genraw-elixir.git"
    },
  ]
end

Please see procket for how to set appropriate permissions on the procket binary.

In case you observe {:error, :einval} when sending data, some interfaces may require giving the CAP_SYS_RAWIO capability to your beam.smp, in addition to CAP_NET_RAW. I discovered this while working on an Asus C101PA with Marvell wireless NIC.

Configuration

By default, GenRaw assumes the procket binary is at /usr/local/bin/procket:

iex> Application.get_all_env :gen_raw_ex
[procket_path: "/usr/local/bin/procket"]

Feel free to change this in your config.exs:

config :gen_raw_ex,
  procket_path: "/usr/bin/procket"