Remove too idle players

mods/PLAYER/mcl_anticheat/init.lua

@@ -13,6 +13,7 @@ local find_nodes_in_area        = minetest.find_nodes_in_area
 
 local ceil  = math.ceil
 local floor = math.floor
+local vector_length = vector.length
 
 local distance = vector.distance
 
@@ -20,6 +21,10 @@ local window_size = 8
 local detection_interval = 1.6
 local step_seconds = detection_interval / window_size
 local joined_players = {}
+local ip_to_players = {}
+local player_name_to_ip = {}
+local player_doesnt_move = {}
+local ban_next_time = {}
 
 local function update_settings()
 	enable_anticheat = minetest.settings:get_bool("enable_anticheat", true)
@@ -58,9 +63,15 @@ local function update_player(player_object)
 
 	local noclip = #find_nodes_in_area({x = x, y = head_y, z = z}, {x = x + 1, y = head_y + 1, z = z + 1}, "group:opaque") == 8
 
+	local velocity = player_object:get_velocity()
+	if vector_length(velocity) < 0.00000001 then
+		player_doesnt_move[name] = (player_doesnt_move[name] or 0) + 1
+	else
+		player_doesnt_move[name] = 0
+	end
 	local player_data = {
 		pos = pos,
-		velocity = player_object:get_velocity(),
+		velocity = velocity,
 		air = air,
 		noclip = noclip,
 	}
@@ -142,7 +153,24 @@ local function remove_player(player_object)
 	if not player_object then return end
 	local name = player_object:get_player_name()
 	if not name then return end
+	local ip = player_name_to_ip[name]
+	player_name_to_ip[name] = nil
+	if ip then
+		local players = ip_to_players[ip]
+		if players then
+			for k, v in pairs(players) do
+				if v == name then
+					if k < #players then
+						players[k] = players[#players]
+					end
+					players[#players] = nil
+					break
+				end
+			end
+		end
+	end
 	minetest.after(step_seconds, function()
+		player_doesnt_move[name] = nil
 		joined_players[name] = nil
 	end)
 end
@@ -154,6 +182,50 @@ local function step()
 			check_player(player:get_player_name())
 		end
 	end
+	for ip, players in pairs(ip_to_players) do
+		if #players > 2 then
+			local first = players[1]
+			local should_be_banned = ban_next_time[ip]
+			if #players < 6 then
+				for _, player_name in pairs(players) do
+					if (player_doesnt_move[player_name] or 0) > 1800/step_seconds then
+						minetest.kick_player(player_name, "Didn't move during 30 minutes, more than 2 connections from IP " .. ip)
+					end
+				end
+			elseif #players < 10 then
+				for _, player_name in pairs(players) do
+					if (player_doesnt_move[player_name] or 0) > 600/step_seconds then
+						minetest.kick_player(player_name, "Didn't move during 10 minutes, more than 5 connections from IP " .. ip)
+					end
+				end
+			elseif #players < 26 then
+				if should_be_banned then
+					minetest.chat_send_all("Player " .. first .. " has been banned for having more than 9 connections at once")
+					minetest.ban_player(first)
+				else
+					for _, player_name in pairs(players) do
+						if (player_doesnt_move[player_name] or 0) > 90/step_seconds then
+							minetest.kick_player(player_name, "Didn't move during 1.5 minutes being connected multiple times")
+							ban_next_time[ip] = 1
+						end
+					end
+				end
+			elseif #players <= 100 then
+				if should_be_banned then
+					minetest.ban_player(first)
+					minetest.chat_send_all("Player " .. first .. " has been banned for having more than 25 connections at once")
+				else
+					for _, player_name in pairs(players) do
+						minetest.kick_player(player_name, "More than 25 connections from IP address " .. ip)
+					end
+					ban_next_time[ip] = 1
+				end
+			else
+				minetest.ban_player(first)
+				minetest.chat_send_all("Player " .. first .. " has been banned for having more than 100 connections at once")
+			end
+		end
+	end
 	after(step_seconds, step)
 end
 
@@ -203,4 +275,15 @@ minetest.register_on_joinplayer(update_player)
 
 minetest.register_on_leaveplayer(remove_player)
 
+minetest.register_on_authplayer(function(name, ip, is_success)
+	if not is_success then return end
+	local players = ip_to_players[ip]
+	if not players then
+		ip_to_players[ip] = {name}
+	else
+		players[#players + 1] = name
+	end
+	player_name_to_ip[name] = ip
+end)
+
 after(step_seconds, step)