Erlang Unix datagram socket

unix_dgram.erl

-module(unix_dgram).
-export([client/1, server/0]).

-define(PF_LOCAL, 1).
-define(SOCK_DGRAM, 2).
-define(UNIX_PATH_MAX, 108).

-define(PATH, <<"/tmp/unix_dgram.sock">>).

server() ->
    {ok, Socket} = procket:socket(?PF_LOCAL, ?SOCK_DGRAM, 0),

    Sun = <<?PF_LOCAL:16/native,        % sun_family
            ?PATH/binary,               % address
            0:((?UNIX_PATH_MAX-byte_size(?PATH))*8)
    >>,
    ok = procket:bind(Socket, Sun),
    echo(Socket).

echo(Socket) ->
    case procket:recvfrom(Socket, 16#FFFF) of
        {error, eagain} ->
            timer:sleep(10),
            echo(Socket);
        {ok, Buf} ->
            io:format("~p~n", [Buf]),
            echo(Socket)
    end.


client(Buf) when is_binary(Buf) ->
    {ok, Socket} = procket:socket(?PF_LOCAL, ?SOCK_DGRAM, 0),

    Sun = <<?PF_LOCAL:16/native,        % sun_family
            ?PATH/binary,               % address
            0:((?UNIX_PATH_MAX-byte_size(?PATH))*8)
    >>,

    procket:sendto(Socket, Buf, 0, Sun).