[s] ports tgstation/tgstation#46425

code/modules/client/client_defines.dm

@@ -75,3 +75,8 @@
 	var/datum/player_details/player_details //these persist between logins/logouts during the same round.
 
 	var/list/char_render_holders			//Should only be a key-value list of north/south/east/west = obj/screen.
+
+	var/client_keysend_amount = 0
+	var/next_keysend_reset = 0
+	var/next_keysend_trip_reset = 0
+	var/keysend_tripped = FALSE

code/modules/keybindings/bindings_client.dm

@@ -4,7 +4,42 @@
 	set instant = TRUE
 	set hidden = TRUE
 
+	client_keysend_amount += 1
+		
+	var/cache = client_keysend_amount
+
+	if(keysend_tripped && next_keysend_trip_reset <= world.time)
+		keysend_tripped = FALSE
+
+	if(next_keysend_reset <= world.time)
+		client_keysend_amount = 0
+		next_keysend_reset = world.time + (1 SECONDS)
+
+	//The "tripped" system is to confirm that flooding is still happening after one spike
+	//not entirely sure how byond commands interact in relation to lag
+	//don't want to kick people if a lag spike results in a huge flood of commands being sent
+	if(cache >= MAX_KEYPRESS_AUTOKICK)
+		if(!keysend_tripped)
+			keysend_tripped = TRUE		
+			next_keysend_trip_reset = world.time + (2 SECONDS)
+		else
+			log_admin("Client [ckey] was just autokicked for flooding keysends; likely abuse but potentially lagspike.")
+			message_admins("Client [ckey] was just autokicked for flooding keysends; likely abuse but potentially lagspike.")
+			QDEL_IN(src, 1)
+			return
+
+	///Check if the key is short enough to even be a real key
+	if(LAZYLEN(_key) > MAX_KEYPRESS_COMMANDLENGTH)
+		to_chat(src, "<span class='userdanger'>Invalid KeyDown detected! You have been disconnected from the server automatically.</span>")
+		log_admin("Client [ckey] just attempted to send an invalid keypress. Keymessage was over [MAX_KEYPRESS_COMMANDLENGTH] characters, autokicking due to likely abuse.")
+		message_admins("Client [ckey] just attempted to send an invalid keypress. Keymessage was over [MAX_KEYPRESS_COMMANDLENGTH] characters, autokicking due to likely abuse.")
+		QDEL_IN(src, 1)
+		return
+	//offset by 1 because the buffer address is 0 indexed because the math was simpler
+	keys_held[current_key_address + 1] = _key
+	//the time a key was pressed isn't actually used anywhere (as of 2019-9-10) but this allows easier access usage/checking
 	keys_held[_key] = world.time
+	current_key_address = ((current_key_address + 1) % HELD_KEY_BUFFER_LENGTH)
 	var/movement = SSinput.movement_keys[_key]
 	if(!(next_move_dir_sub & movement) && !keys_held["Ctrl"])
 		next_move_dir_add |= movement
@@ -35,7 +70,11 @@
 	set instant = TRUE
 	set hidden = TRUE
 
-	keys_held -= _key
+	//Can't just do a remove because it would alter the length of the rolling buffer, instead search for the key then null it out if it exists
+	for(var/i in 1 to HELD_KEY_BUFFER_LENGTH)
+		if(keys_held[i] == _key)
+			keys_held[i] = null
+			break
 	var/movement = SSinput.movement_keys[_key]
 	if(!(next_move_dir_add & movement))
 		next_move_dir_sub |= movement

code/modules/keybindings/setup.dm

@@ -1,9 +1,14 @@
 /client
-	var/list/keys_held = list() // A list of any keys held currently
-	// These next two vars are to apply movement for keypresses and releases made while move delayed.
-	// Because discarding that input makes the game less responsive.
-	var/next_move_dir_add // On next move, add this dir to the move that would otherwise be done
-	var/next_move_dir_sub // On next move, subtract this dir from the move that would otherwise be done
+	/// A rolling buffer of any keys held currently
+	var/list/keys_held = list()
+	///used to keep track of the current rolling buffer position
+	var/current_key_address = 0
+	/// These next two vars are to apply movement for keypresses and releases made while move delayed.
+	/// Because discarding that input makes the game less responsive.
+ 	/// On next move, add this dir to the move that would otherwise be done
+	var/next_move_dir_add
+ 	/// On next move, subtract this dir from the move that would otherwise be done
+	var/next_move_dir_sub
 
 // Set a client's focus to an object and override these procs on that object to let it handle keypresses
 
@@ -31,6 +36,11 @@
 /client/proc/set_macros()
 	set waitfor = FALSE
 
+	//Reset and populate the rolling buffer
+	keys_held.Cut()
+	for(var/i in 1 to HELD_KEY_BUFFER_LENGTH)
+		keys_held += null
+
 	erase_all_macros()
 
 	var/list/macro_sets = SSinput.macro_sets