From 378ce1b6bc3822b1eec7ff12ce2e0699bc4d84e8 Mon Sep 17 00:00:00 2001
From: j4nk <axe@smelly.cologne>
Date: Sun, 23 Mar 2025 17:14:21 -0400
Subject: [PATCH] Clients periodically ping server, server checks for
 disconnects

---
 lobby.lua | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 57 insertions(+), 2 deletions(-)

diff --git a/lobby.lua b/lobby.lua
index bf1a6db..f585e0b 100644
--- a/lobby.lua
+++ b/lobby.lua
@@ -13,11 +13,33 @@ OCT_LOBBY_MSG_NAK = 6; -- "no"
 -- end message type constants
 
 oct_lobby_clientlist = {};
-oct_lobby_timers = {};
-oct_lobby_timers["clientlist"] = 1000; -- Every 1000 calls to lobby_client broadcast client list
 
 server_needs_broadcast_client_list = false
+lobby_server_first_call = true
+
+function lobby_server_checkclients()
+   for k,v in pairs(oct_lobby_clientlist)
+   do
+	  -- if we weren't pinged, remove the client
+	  if not v["pinged"]
+	  then
+		 OCT_LOG_WARNING("Lost connection to " .. k)
+		 oct_lobby_clientlist[k] = nil -- remove the client
+		 server_needs_broadcast_client_list = true -- rebroadcast the client list
+	  else
+		 v["pinged"] = false
+	  end
+   end
+
+   oct_timer_register("lobby_server_checkclients", 3000, "lobby_server_checkclients", "")
+end
+
 function lobby_server(maxplayers)
+   if lobby_server_first_call then
+	  oct_timer_register("lobby_server_checkclients", 3000, "lobby_server_checkclients", "")
+	  lobby_server_first_call = false
+   end
+
    msg,addr,port = oct_recv();
    if (msg ~= "") then
 	  msg_obj = json.decode(msg)[1] -- dumps to 1-elem array, get first elem
@@ -50,6 +72,7 @@ function lobby_server(maxplayers)
 			oct_lobby_clientlist[req_name] = {}
 			oct_lobby_clientlist[req_name]["addr"] = req_addr
 			oct_lobby_clientlist[req_name]["port"] = req_port
+			oct_lobby_clientlist[req_name]["pinged"] = false
 			OCT_LOG_INFO("Registered new client: " .. req_name .. " @ " .. req_addr .. ":" .. req_port)
 			
 			oct_send(response, req_addr, req_port)
@@ -57,8 +80,24 @@ function lobby_server(maxplayers)
 			server_needs_broadcast_client_list = true
 		 end
 	  end
+	  
+	  if (msg_obj["msg_type"] == OCT_LOBBY_MSG_PING) then
+		 req_addr = convert_known_host_to_ip(addr)
+		 for k,v in pairs(oct_lobby_clientlist)
+		 do
+			-- TODO this is insecure
+			-- have server issue a token based on a random number on registration and check against that
+			-- like SHA256(addr::port::rand())
+			if v["addr"] == req_addr and k == msg_obj["name"]
+			then
+			   v["pinged"] = true
+			   break
+			end
+		 end
+	  end
    end
 
+
    if (server_needs_broadcast_client_list == true) then
 	  msg = json.encode({
 			{ msg_type = OCT_LOBBY_MSG_CLIENTLIST,
@@ -106,6 +145,15 @@ function lobby_clear_connect_form()
    unregister_textbox(lobby_name_textbox)
 end
 
+-- every 1 second, ping the server to let it know we are still alive
+function lobby_client_ping()
+   local msg = json.encode({
+		 { msg_type=OCT_LOBBY_MSG_PING, name=client_connect_name }
+   })
+   oct_send(msg, client_connect_ip, client_connect_port)
+   oct_timer_register("ping_server", 1000, "lobby_client_ping", "")
+end
+
 --function lobby_client(ip, port, name, my_port)
 function lobby_client(key, ch, my_port)
    if (lobby_first_call)
@@ -173,6 +221,13 @@ function lobby_client(key, ch, my_port)
 		 client_wait_for_reg_response = false
 		 client_filling_in_connect_form = false
 		 lobby_clear_connect_form()
+		 -- ping the server to let them know we are alive
+		 local ping_msg = json.encode({
+			   { msg_type=OCT_LOBBY_MSG_PING, name=client_connect_name }
+		 })
+		 oct_send(ping_msg, client_connect_ip, client_connect_port)
+		 -- then ping every second
+		 oct_timer_register("ping_server", 1000, "lobby_client_ping", "")
 
 		 -- Registration was unsuccessful
 	  elseif (client_wait_for_reg_response == true and