Really Insecure Magcard Rolldoor Controller

local component = require "component"
local net = require "internet"
local event = require "event"
local fs = require "filesystem"
local rd = component.os_rolldoorcontroller
local magcard = component.os_magreader
local lamp = component.colorful_lamp
magcard.setEventName "magswipe"
rd.setSpeed(3)
rd.close()

local function set_lamp(r, g, b)
    lamp.setLampColor(r * 1024 + g * 32 + b)
end

local function fetch(url)
    local txt = ""
    for chunk in net.request(url) do
        txt = txt .. chunk
    end
    return txt
end

local function read_file(file)
    return io.open(file):read "*a"
end

local function load_data(dat)
    local fn, err = load("return " .. dat, "=data", "t", {})
    if not fn then return false, err
    else
        local ok, res = pcall(fn)
        if not ok then return false, res
        else return true, res end
    end
end

local function open()
    rd.open()
    os.sleep(3)
    rd.close()
end

local ok, config = load_data(read_file "/home/conf.lua")
if not ok then error(config) end

if not config.door_name then error "Door name not specified." end
if not config.data_URL then error "Data URL not specified." end

local function authorized(player, card)
    print("Player:", player, "Card data:", card)
    local ok, sysdata = load_data(fetch(config.data_URL))
    if not ok then print("DOOR DATA FORMAT ERROR:", sysdata) return false end
    if player ~= card then return false end
    local player_clearance = sysdata.players[player]
    if not player_clearance then print("Player", player, "not found") return false end
    local door_clearance = sysdata.doors[config.door_name]
    return door_clearance <= player_clearance
end

while true do
    set_lamp(0, 0, 31)
    local _, _, player_name, card_data, player_UUID = event.pull "magswipe"
    if authorized(player_name, card_data) then
        set_lamp(0, 31, 0)
        open()
    else
        set_lamp(31, 0, 0)
        os.sleep(1)
    end
end