How build non-blocking TCP server with ssl encryption

Question

Non-blocking TCP server on trapexit.org explains how to build server based on tcp_gen, but i want to modify this example and make it work with ssl. For now i have completely no idea how to replace

{ok, Ref} = prim_inet:async_accept(Listen_socket, -1)

Answer 1

Do not replace this with anything. Instead connect your input and output to the SSL handler.

spender is right, SSL uses TCP for transport.

Here someone seems to have implemented SSL over async TCP.

Answer 2

simple echo_ssl with multi threading

-module(echo_ssl).
-compile([export_all]).

main() ->
    application:start(crypto),
    application:start(ssl),
    ssl:seed("TODO random here"),
    {ok, ListenSocket} = ssl:listen(2840, [
        {ssl_imp, new},
        {active, false},
        {verify, 0},
        {mode,binary},
        {cacertfile, "certs/etc/server/cacerts.pem"},
        {certfile, "certs/etc/server/cert.pem"},
        {keyfile, "certs/etc/server/key.pem"}
    ]),
    io:format("ready to accept connections at port 2840 ~p\n", [ListenSocket]),
    server_loop(ListenSocket).

server_loop(ListenSocket) ->
    {ok, Socket} = ssl:transport_accept(ListenSocket),
    io:format("accepted connection from ~p\n", [ssl:peername(Socket)]),
    ssl:ssl_accept(Socket),
    spawn(fun() -> loop(Socket) end),
    server_loop(ListenSocket).

loop(Socket) ->
    io:format("waiting for packet~n"),
    case ssl:recv(Socket, 1000, 2000) of
        {ok, Data} ->
            io:format("received data: ~s~n", [binary_to_list(Data)]),
            Return = ssl:send(Socket, Data),
            io:format("sending ~p~n", [Return]),
            loop(Socket);
        {error, timeout} ->
           loop(Socket);
        Else ->
            io:format("crap ~p~n",[Else])
    end.