From d1fa980f11ca31c50f030a099947705eb69683ac Mon Sep 17 00:00:00 2001
From: Maciej Szlosarczyk <maciej@sosek.net>
Date: Mon, 27 May 2019 10:34:29 +0300
Subject: [PATCH] Create OTP structure for TCP side of the module

---
 apps/epp_proxy/src/epp_tcp_acceptor.erl | 44 ++++++++++++
 apps/epp_proxy/src/epp_tcp_worker.erl   | 95 +++++++++++++++++++++++++
 apps/epp_proxy/src/pool_supervisor.erl  | 16 +++++
 3 files changed, 155 insertions(+)
 create mode 100644 apps/epp_proxy/src/epp_tcp_acceptor.erl
 create mode 100644 apps/epp_proxy/src/epp_tcp_worker.erl
 create mode 100644 apps/epp_proxy/src/pool_supervisor.erl

diff --git a/apps/epp_proxy/src/epp_tcp_acceptor.erl b/apps/epp_proxy/src/epp_tcp_acceptor.erl
new file mode 100644
index 0000000..757106e
--- /dev/null
+++ b/apps/epp_proxy/src/epp_tcp_acceptor.erl
@@ -0,0 +1,44 @@
+-module(epp_tcp_acceptor).
+
+-behaviour(gen_server).
+-define(SERVER, ?MODULE).
+-define(POOL_SUPERVISOR, pool_supervisor).
+-define(WORKER, epp_tcp_worker).
+
+
+%% gen_server callbacks
+-export([init/1, handle_cast/2, handle_call/3, start_link/1]).
+
+-record(state, {socket, port, options}).
+
+start_link(Port) ->
+    gen_server:start_link({local, ?SERVER}, ?MODULE, Port, []).
+
+init(Port) ->
+    Options = [binary,
+               {packet, raw},
+               {active, false},
+               {reuseaddr, true}],
+
+    {ok, ListenSocket} = gen_tcp:listen(Port, Options),
+    gen_server:cast(self(), accept),
+
+    {ok, #state{socket=ListenSocket, port=Port, options=Options}}.
+
+handle_cast(accept, State = #state{socket=ListenSocket, port=Port, options=Options}) ->
+    {ok, AcceptSocket} = gen_tcp:accept(ListenSocket),
+    {ok, NewOwner} = create_worker(AcceptSocket),
+    ok = gen_tcp:controlling_process(AcceptSocket, NewOwner),
+    gen_server:cast(NewOwner, greeting),
+    gen_server:cast(self(), accept),
+    {noreply, State#state{socket=ListenSocket, port=Port, options=Options}}.
+
+handle_call(_E, _From, State) -> {noreply, State}.
+
+create_worker(Socket) ->
+    ChildSpec = #{id => rand:uniform(),
+                   type => worker,
+                   modules => [?WORKER],
+                   restart => temporary,
+                   start => {?WORKER, start_link, [Socket]}},
+    supervisor:start_child(?POOL_SUPERVISOR, ChildSpec).
diff --git a/apps/epp_proxy/src/epp_tcp_worker.erl b/apps/epp_proxy/src/epp_tcp_worker.erl
new file mode 100644
index 0000000..da3980f
--- /dev/null
+++ b/apps/epp_proxy/src/epp_tcp_worker.erl
@@ -0,0 +1,95 @@
+-module(epp_tcp_worker).
+
+-behaviour(gen_server).
+-define(SERVER, ?MODULE).
+
+%% gen_server callbacks
+-export([init/1, handle_cast/2, handle_call/3, start_link/1]).
+-export([terminate/2, code_change/3]).
+
+-record(state,{socket, length, session_id}).
+
+init(Socket) ->
+    logger:info("Created a test process"),
+    {ok, #state{socket=Socket}}.
+
+start_link(Socket) ->
+    gen_server:start_link(?MODULE, Socket, []).
+
+handle_cast(serve, State = #state{socket=Socket}) ->
+    {noreply, State#state{socket=Socket}};
+handle_cast(greeting, State = #state{socket=Socket}) ->
+    SessionId = session_id(),
+
+    {Status, StatusCode, Headers, ClientRef} =
+        hackney:request(get, router:route_request("hello"), [], "",
+                        [{cookie, [<<"session=">>, SessionId]}, insecure]),
+
+    Body = <<"Some BODY">>,
+
+    Length = byte_size(Body) + 4,
+    ByteSize = << Length:32/big >>,
+    io:format("State: ~p~n", [State]),
+    write_line(Socket, ByteSize),
+    write_line(Socket, Body),
+    gen_server:cast(self(), read_length),
+    {noreply, State#state{socket=Socket}};
+handle_cast(read_length, State = #state{socket=Socket}) ->
+    case read_length(Socket) of
+        {ok, Data} ->
+            NewState = State#state{length=Data},
+            gen_server:cast(self(), read_frame),
+            {noreply, NewState};
+        {error, _Details} ->
+            {stop, normal, State}
+        end;
+handle_cast(read_frame, State = #state{socket=Socket, length=Length}) ->
+    case read_frame(Socket, Length) of
+        {ok, Data} ->
+            ByteLength = byte_size(Data) + 4,
+            ByteSize = << ByteLength:32/big >>,
+            write_line(Socket, ByteSize),
+            write_line(Socket, Data),
+            gen_server:cast(self(), read_length),
+            {noreply, State};
+        {error, _Details} ->
+            {stop, normal, State}
+    end;
+handle_cast(Message, State) ->
+    logger:info("Received message ~p.~n", [Message]),
+    {noreply, State}.
+
+handle_call(_E, _From, State) -> {noreply, State}.
+terminate(_Reason, _State) ->
+    ok.
+code_change(_OldVersion, State, _Extra) -> {ok, State}.
+
+%% Private function
+write_line(Socket, Line) ->
+    gen_tcp:send(Socket, Line).
+
+read_length(Socket) ->
+    case gen_tcp:recv(Socket, 4) of
+        {ok, Data} ->
+            Length = binary:decode_unsigned(Data, big),
+            io:format("Preparing to receive: ~p~n", [Length]),
+            {ok, Length - 4};
+        {error, Reason} ->
+            io:format("Error: ~p~n", [Reason]),
+            {error, Reason}
+    end.
+
+read_frame(Socket, FrameLength) ->
+    case gen_tcp:recv(Socket, FrameLength) of
+        {ok, Data} ->
+            io:format("Frame: ~p~n", [Data]),
+            {ok, Data};
+        {error, Reason} ->
+            io:format("Error: ~p~n", [Reason]),
+            {error, Reason}
+    end.
+
+session_id() ->
+    UniqueMap = epp_util:create_map(self()),
+    BinaryHash = epp_util:create_session_id(UniqueMap),
+    BinaryHash.
diff --git a/apps/epp_proxy/src/pool_supervisor.erl b/apps/epp_proxy/src/pool_supervisor.erl
new file mode 100644
index 0000000..cb617b4
--- /dev/null
+++ b/apps/epp_proxy/src/pool_supervisor.erl
@@ -0,0 +1,16 @@
+-module(pool_supervisor).
+
+-behaviour(supervisor).
+
+-export([start_link/0]).
+
+-export([init/1]).
+
+-define(SERVER, ?MODULE).
+
+start_link() ->
+    supervisor:start_link({local, ?SERVER}, ?MODULE, []).
+
+init([]) ->
+    SupFlags = #{strategy => one_for_one, intensity => 3, period => 60},
+    {ok, {SupFlags, []}}.