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%% Feel free to use, reuse and abuse the code in this file.
-module(reverse_protocol).
-behaviour(gen_server).
-behaviour(ranch_protocol).
%% API.
-export([start_link/4]).
%% gen_server.
-export([init/1]).
-export([init/4]).
-export([handle_call/3]).
-export([handle_cast/2]).
-export([handle_info/2]).
-export([terminate/2]).
-export([code_change/3]).
-define(TIMEOUT, 5000).
-record(state, {socket, transport}).
%% API.
start_link(Ref, Socket, Transport, Opts) ->
proc_lib:start_link(?MODULE, init, [Ref, Socket, Transport, Opts]).
%% gen_server.
%% This function is never called. We only define it so that
%% we can use the -behaviour(gen_server) attribute.
init([]) -> {ok, undefined}.
init(Ref, Socket, Transport, _Opts = []) ->
ok = proc_lib:init_ack({ok, self()}),
ok = ranch:accept_ack(Ref),
ok = Transport:setopts(Socket, [{active, once}]),
gen_server:enter_loop(?MODULE, [],
#state{socket=Socket, transport=Transport},
?TIMEOUT).
handle_info({tcp, Socket, Data}, State=#state{
socket=Socket, transport=Transport}) ->
Transport:setopts(Socket, [{active, once}]),
Transport:send(Socket, reverse_binary(Data)),
{noreply, State, ?TIMEOUT};
handle_info({tcp_closed, _Socket}, State) ->
{stop, normal, State};
handle_info({tcp_error, _, Reason}, State) ->
{stop, Reason, State};
handle_info(timeout, State) ->
{stop, normal, State};
handle_info(_Info, State) ->
{stop, normal, State}.
handle_call(_Request, _From, State) ->
{reply, ok, State}.
handle_cast(_Msg, State) ->
{noreply, State}.
terminate(_Reason, _State) ->
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%% Internal.
reverse_binary(B) when is_binary(B) ->
[list_to_binary(lists:reverse(binary_to_list(
binary:part(B, {0, byte_size(B)-2})
))), "\r\n"].
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