Erlang DTLS sample client

dtls_client.erl

-module(dtls_client).

-export([connect/1]).

psk_verify(Username, UserState) ->
    io:format("Server Hint: ~p~n", [Username]),
    {ok, UserState}.

connect(Port) ->
    [application:start(X) || X <- [crypto, asn1, public_key, ssl]],

    %% Opts = [{ciphers,[{dhe_dss,aes_256_cbc,sha256}]},
    Opts = [
	    {ssl_imp,new},
	    {active, false},
	    {verify, 0},

	    {protocol, dtls},
	    {versions, ['dtlsv1.2']},
%%	    {ciphers,[{ecdhe_rsa, aes_128_cbc, sha256}]},
	    {cb_info, {dtls_udp, dtls_udp, udp_close, udp_error}}

	    %% {versions, ['tlsv1.2']},
	    %% {ciphers,[{ecdhe_rsa,chacha20_poly1305,null}]}

	    %% {srp_identity, {"Test-User", "secret"}},
	    %% {ciphers, [{srp_anon, aes_256_cbc, sha}]},
	    %% {psk_identity, "Client_identity"},
	    %% {psk_lookup_fun, {fun psk_verify/2, <<16#11>>}},
	    %% {versions, [tlsv1]},
	    %% {ciphers,[{rsa_psk, aes_256_cbc, sha}]},
	    %% {reuseaddr,true}
	   ],

    %%{ok, Host} = inet:gethostname(),
    Host = {127,0,0,1},
    {ok, CSock} = ssl:connect(Host, Port, Opts),
    io:fwrite("Connect: connected.~n"),
    {ok, Data} = ssl:recv(CSock, 0),
    io:fwrite("Connect: got data: ~p~n", [Data]),
    io:fwrite("Connect: closing and terminating.~n"),
    ssl:close(CSock).