Implement demo of DER comms

client/src/main_window.vala

@@ -14,7 +14,9 @@ namespace StudySystemClient {
 
 			this.connection = connection;
 			connection.received.connect((msg) => {
-					response_label.label = "Response: " + (string)msg;
+					var der = Der.decode(msg) as Der.Choice;
+					var str = der.value as Der.Utf8String;
+					response_label.label = "Response: " + str.value;
 				});
 
 			var box = new Gtk.Box(Gtk.Orientation.VERTICAL, 10);
@@ -24,7 +26,10 @@ namespace StudySystemClient {
 			box.margin_bottom = 10;
 
 			send_button = new Gtk.Button.with_label("Send");
-			send_button.clicked.connect(() => connection.send("Foo".data));
+			send_button.clicked.connect(() => {
+					var msg = new Der.Choice(0, new Der.Null());
+					connection.send(msg.encode());
+				});
 			box.append(send_button);
 
 			response_label = new Gtk.Label("");

server/.gitignore

@@ -1,2 +1,3 @@
 _build/*
 *.beam
+src/StudySystemProtocol.erl

server/asn1/StudySystemProtocol.asn1

@@ -0,0 +1,11 @@
+StudySystemProtocol DEFINITIONS EXPLICIT TAGS ::= BEGIN
+
+Request ::= CHOICE {
+	foo [0] NULL
+}
+
+Response ::= CHOICE {
+	msg [0] UTF8String
+}
+
+END

server/rebar.config

@@ -1,2 +1,6 @@
 {erl_opts, [debug_info]}.
 {deps, []}.
+{plugins, [{provider_asn1, "0.4.1"}]}.
+{provider_hooks, [{pre, [{compile, {asn, compile}}]},
+				  {post, [{clean, {asn, clean}}]}]}.
+{asn1_args, [{compile_opts, [der]}]}.

server/src/proto_sup.erl

@@ -11,10 +11,16 @@ start_link(Port, CertDir) ->
 	supervisor:start_link({local, ?MODULE}, ?MODULE, [Port, CertDir]).
 
 init([Port, CertDir]) ->
-	SupFlags = #{stragegy => one_for_all,
+	SupFlags = #{stragegy => one_for_one,
 				 intensity => 1,
 				 period => 5},
-	ChildSpecs = [#{id => tcp_server,
+	ChildSpecs = [#{id => session_sup,
+					start => {session_sup, start_link, []},
+					restart => permanent,
+					shutdown => 5000,
+					type => supervisor,
+					modules => [session_sup]},
+				  #{id => tcp_server,
 					start => {tcp_server, start_link, [Port, CertDir]},
 					restart => permanent,
 					shutdown => 5000,

server/src/session_server.erl

@@ -0,0 +1,42 @@
+% Copyright (c) Camden Dixie O'Brien
+% SPDX-License-Identifier: AGPL-3.0-only
+
+-module(session_server).
+-behaviour(gen_server).
+
+-export([start_link/1]).
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
+		 terminate/2, code_change/3]).
+
+start_link(Socket) ->
+	gen_server:start_link(?MODULE, Socket, []).
+
+init(Socket) ->
+	ssl:setopts(Socket, [{active, true}]),
+	{ok, #{socket => Socket}}.
+
+handle_call(_Request, _From, State) ->
+	{reply, ok, State}.
+
+handle_cast(_Msg, State) ->
+	{noreply, State}.
+
+handle_info({ssl, Socket, Data}, State) ->
+	case 'StudySystemProtocol':decode('Request', Data) of
+		{ok, {foo, _}} ->
+			{ok, Encoded}
+				= 'StudySystemProtocol':encode('Response', {msg, "Foo"}),
+			ssl:send(Socket, Encoded);
+		Result ->
+			io:format("Invalid message: ~p~n", [Result]),
+			ok
+	end,
+	{noreply, State};
+handle_info(_Info, State) ->
+	{noreply, State}.
+
+terminate(_Reason, #{socket := Socket}) ->
+	ssl:close(Socket).
+
+code_change(_OldVsn, State, _Extra) ->
+	{ok, State}.

server/src/session_sup.erl

@@ -0,0 +1,25 @@
+% Copyright (c) Camden Dixie O'Brien
+% SPDX-License-Identifier: AGPL-3.0-only
+
+-module(session_sup).
+-behaviour(supervisor).
+
+-export([start_link/0, init/1, start_session/1]).
+
+start_link() ->
+	supervisor:start_link({local, ?MODULE}, ?MODULE, []).
+
+init([]) ->
+	SupFlags = #{strategy => simple_one_for_one,
+				 intensity => 10,
+				 period => 1},
+	ChildSpec = #{id => session_server,
+				  start => {session_server, start_link, []},
+				  restart => temporary,
+				  shutdown => 5000,
+				  type => worker,
+				  modules => [session_server]},
+	{ok, {SupFlags, [ChildSpec]}}.
+
+start_session(Socket) ->
+	supervisor:start_child(?MODULE, [Socket]).

server/src/tcp_server.erl

@@ -20,8 +20,8 @@ init([Port, CertDir]) ->
 			   {verify, verify_peer},
 			   {fail_if_no_peer_cert, true}],
 	{ok, Socket} = ssl:listen(Port, TcpOpts ++ SslOpts),
-	Pid = spawn_link(fun() -> acceptor_loop(Socket) end),
+	self() ! accept,
-	{ok, #state{socket = Socket, acceptor = Pid}}.
+	{ok, #state{socket = Socket}}.
 
 handle_call(_Request, _From, State) ->
 	{reply, ok, State}.
@@ -29,46 +29,30 @@ handle_call(_Request, _From, State) ->
 handle_cast(_Msg, State) ->
 	{noreply, State}.
 
-handle_info({'EXIT', Pid, Reason}, State = #state{acceptor = Pid}) ->
+handle_info(accept, State = #state{socket = Socket}) ->
-	{stop, {acceptor_died, Reason}, State};
+	case ssl:transport_accept(Socket) of
+		{ok, TlsSocket} ->
+			self() ! {handshake, TlsSocket},
+			self() ! accept;
+		{error, closed} ->
+			ok
+	end,
+	{noreply, State};
+handle_info({handshake, TlsSocket}, State) ->
+	case ssl:handshake(TlsSocket) of
+		{ok, ClientSocket} ->
+			{ok, Pid} = session_sup:start_session(ClientSocket),
+			ok = ssl:controlling_process(ClientSocket, Pid);
+		{error, _Reason} ->
+			ok
+	end,
+	{noreply, State};
 handle_info(_Info, State) ->
 	{noreply, State}.
 
 terminate(_Reason, #state{socket = Socket}) ->
-	gen_tcp:close(Socket),
+	ssl:close(Socket),
 	ok.
 
 code_change(_OldVsn, State, _Extra) ->
 	{ok, State}.
-
-acceptor_loop(Socket) ->
-	case ssl:transport_accept(Socket) of
-		{ok, TlsSocket} ->
-			case ssl:handshake(TlsSocket) of
-				{ok, ClientSocket} ->
-					Pid = spawn(
-							fun() -> handle_connection(ClientSocket) end),
-					ok = ssl:controlling_process(ClientSocket, Pid),
-					acceptor_loop(Socket);
-				{error, _Reason} ->
-					acceptor_loop(Socket)
-			end;
-		{error, closed} ->
-			ok
-	end.
-
-handle_connection(Socket) ->
-	ssl:setopts(Socket, [{active, true}]),
-	handle_connection_loop(Socket).
-
-handle_connection_loop(Socket) ->
-	receive
-		{ssl, Socket, Data} ->
-			handle_client_msg(Socket, Data),
-			handle_connection_loop(Socket);
-		{ssl_closed, Socket} ->
-			ok
-	end.
-
-handle_client_msg(Socket, Msg) ->
-	ssl:send(Socket, Msg).