PlayMinetestServer/mods/vps_blocker/init.lua

--  Vps Blocker

local http = minetest.request_http_api()
assert(http ~= nil, "You need to add vps_blocker to secure.http_mods")

local kick_message = minetest.settings:get("vps_kick_message") or "You are using a proxy, vpn or other hosting services, please disable them to play on this server."

vps_blocker = {}
local cache = {}
local storage = minetest.get_mod_storage()
--[[
cache of ip == nil not checked yet
                 == 1 checked allow
                 == 2 checked deny
]]

local checkers = {}

--[[
vps_blocker.register_check(check):
passed check is a array:

getreq(ip) return req, callback or nil, err for failed

callback func will get the result of the req and is supposed
to return true for allow and false for denying the client
nil, err for failed requests

active = true
If the checker is currently working is true by default

The checker can store any other data inside this table.
]]

function vps_blocker.register_checker(check)
  assert(type(check) == "table")
  check.active = true
  assert(type(check.getreq) == "function")
  --  Dummy testing function:
  local req, call = check.getreq("0.0.0.0")
  assert(type(req) == "table")
  assert(type(req.url == "string"))
  assert(type(call) == "function")
  table.insert(checkers, check)
end

--  Load checkers
dofile(minetest.get_modpath(minetest.get_current_modname()).. "/checker.lua")

--  Add the main ipcheckup function
local function check_ip(name, ip, hash)
  --  Loop throught the list of checkers and use one
  local checked = false
  for _, check in pairs(checkers) do
    if check.active then
      local req, call = check.getreq(ip)
      if req then
        function callback(result)
          local pass, err = call(result)
          if pass then
            cache[hash] = 1
            minetest.log("action", "vps_blocker: Passing good-ip-player "..name.." ["..ip.."]")
          elseif pass == false then
            cache[hash] = 2
            minetest.log("action", "vps_blocker: Kicking bad-ip-player "..name.." ["..ip.."]")
          else minetest.log("error", "vps_blocker: Callback-Error "..err.." while checking "..name.." ["..ip.."]!")
          end
        end
        http.fetch(req, callback)
        checked = true
        break
      else minetest.log("error", "vps_blocker: Checker failed to create requests for "..name.." ["..ip.."]!")
      end
    end
  end
  --  Report error if no working was found
  if not checked then
    minetest.log("error", "vps_blocker: No working checker found!")
  end
end

--  Add a function which handels what do do(check, kick, nth...)
function vps_blocker.handle_player(name, ip)
  if not ip or not name then
    return
  end
  local iphash = minetest.sha1(ip)
  if not iphash then
    return
  end
  if cache[iphash] == 1 or storage:get_int(name) == 1 then
    return
  end
  if not cache[iphash] then
    check_ip(name, ip, iphash)
    return
  end
  if cache[iphash] == 2 then
    local player = minetest.get_player_by_name(name)
    if player then
      --  Kick after a server step, to prevent other on_joinplayer to crash
      minetest.after(0, function()
        minetest.kick_player(name, kick_message)
      end)
    else return kick_message
    end
  end
end

--  Do handle_player on prejoin and normal join
minetest.register_on_prejoinplayer(vps_blocker.handle_player)
minetest.register_on_joinplayer(function(player)
  local name = player:get_player_name()
  local ip = minetest.get_player_ip(name)
  vps_blocker.handle_player(name, ip)
end)

--  Add a command to whitelist players
minetest.register_chatcommand("vps_wl", {
  description = "Allow a player to use vps services.",
  params = "<add or remove> <name>",
  privs = {server=true},
  func = function(name, params)
    local p = string.split(params, " ")
    if p[1] == "add" then
      storage:set_int(p[2], 1)
      return true, "Added "..p[2].." to the whitelist."
    elseif p[1] == "remove" then
      storage:set_int(p[2], 0)
      return true, "Removed "..p[2].." from the whitelist."
    else return false, "Invalid Input"
    end
  end
})