iecho.erl

-module(iecho).
-include_lib("procket/include/procket.hrl").

-export([listen/0, listen/1]).

%%%
%%% Warning: error handling omitted, leaks fd's on error
%%%

listen() ->
    listen(0).

listen(Port) ->
    ok = inert:start(),

    {ok, Socket} = procket:socket(inet, stream, 0),
    Sockaddr = <<
        (procket:sockaddr_common(procket:family(inet), 16))/binary,
        Port:16,        % Port
        0,0,0,0,        % IPv4 ANY address
        0:64
        >>,
    BACKLOG = 1024,
    ok = procket:bind(Socket, Sockaddr),
    ok = procket:listen(Socket, BACKLOG),

    {ok, <<_:16, ListenPort:16, _/binary>>} = procket:getsockname(Socket, Sockaddr),
    error_logger:info_report([{listening, ListenPort}]),

    accept(Socket).

accept(Listen) ->
    {ok,read} = inert:poll(Listen),
    {ok, Socket} = procket:accept(Listen),
    spawn(fun() -> echo(Socket) end),
    accept(Listen).

accept(Listen) ->
    {ok,read} = inert:poll(Listen),
    {ok, Socket} = procket:accept(Listen),
    spawn(fun() -> echo(Socket) end),
    accept(Listen).

echo(Socket) ->
    {ok,read} = inert:poll(Socket),
    case procket:read(Socket, 16#ffff) of
        {ok, <<>>} ->
            ok = procket:close(Socket),
            ok;
        {ok, Buf} ->
            {ok,write} = inert:poll(Socket, [{mode, write}]),
            ok = procket:write(Socket, Buf),
            echo(Socket)
    end.