From 53857bc613224be3cb6e5864aefc8bd1f2fa033f Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cdo@wip.sh>
Date: Tue, 25 Feb 2025 15:57:26 +0000
Subject: [PATCH] Fix message dropping issue on server

The sockets were initially set to active, which meant that data
received immediately after the TLS handshake (before the socket was
transferred to the handle_connection process) were received by the
acceptor process and hence were not handled.
---
 server/src/tcp_server.erl | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/server/src/tcp_server.erl b/server/src/tcp_server.erl
index 2714c29..80133d8 100644
--- a/server/src/tcp_server.erl
+++ b/server/src/tcp_server.erl
@@ -14,12 +14,12 @@ start_link(Port, CertDir) ->
 	gen_server:start_link({local, ?MODULE}, ?MODULE, [Port, CertDir], []).
 
 init([Port, CertDir]) ->
+	TcpOpts = [binary, inet6, {active, false}, {reuseaddr, true}],
 	SslOpts = [{certfile, filename:join([CertDir, "server.pem"])},
 			   {cacertfile, filename:join([CertDir, "ca.pem"])},
 			   {verify, verify_peer},
 			   {fail_if_no_peer_cert, true}],
-	{ok, Socket} =
-		ssl:listen(Port, [binary, inet6, {active, true} | SslOpts]),
+	{ok, Socket} = ssl:listen(Port, TcpOpts ++ SslOpts),
 	Pid = spawn_link(fun() -> acceptor_loop(Socket) end),
 	{ok, #state{socket = Socket, acceptor = Pid}}.
 
@@ -49,7 +49,6 @@ acceptor_loop(Socket) ->
 					Pid = spawn(
 							fun() -> handle_connection(ClientSocket) end),
 					ok = ssl:controlling_process(ClientSocket, Pid),
-					ssl:setopts(ClientSocket, [{active, true}]),
 					acceptor_loop(Socket);
 				{error, _Reason} ->
 					acceptor_loop(Socket)
@@ -59,10 +58,17 @@ acceptor_loop(Socket) ->
 	end.
 
 handle_connection(Socket) ->
+	ssl:setopts(Socket, [{active, true}]),
+	handle_connection_loop(Socket).
+
+handle_connection_loop(Socket) ->
 	receive
 		{ssl, Socket, Data} ->
-			ssl:send(Socket, Data),
-			handle_connection(Socket);
+			handle_client_msg(Socket, Data),
+			handle_connection_loop(Socket);
 		{ssl_closed, Socket} ->
 			ok
 	end.
+
+handle_client_msg(Socket, Msg) ->
+	ssl:send(Socket, Msg).