client.lua

local event = require("event")
local com = require("component")
local sides = require("sides")
local term = require("term")
local text = require("text")
local r = com.redstone
local mod = com.modem
local dat = com.data
local gpu = com.gpu
local rsa = require("rsa")
local classes = require("classes")
local ser = require("serialization")

local message = ""
local sender = ""
local side = sides.back
local server = {}
local running = true
local waiting = true
local localport = math.random(35000,40000)
local pubKey,prvKey = rsa.makeKeyPairs(25)
print(pubKey:toString())
math.randomseed(math.floor(os.time()/4)+(os.time()%4))

local function printData(...)
  for i,v in ipairs(...) do
    print(i..": "..v)
  end
end

local function foldData(...)
  --
  -- glue messages together for transport
  --
  local message = ""
  for i,s in ipairs({...}) do message = message..(message ~= "" and "#" or "")..s end
  return message
end

local function unfoldData(message)
    --
    -- split data for processing
    --
    local data = {}
    _ = message:gsub("#?[%w$]+",function(s) table.insert(data,(s:sub(1,1) == "#") and s:sub(2) or s) end)
    return data
end

local function sendData(encrypt,...)
  --
  -- process data that should be send
  --
  local message = foldData(...)
  if encrypt then
    message = server.key:encrypt(message)
  end
  mod.send(server.id,tonumber(server.port),message)
end

local function recvData(message)
  --
  -- process recieved data
  --
  if message:sub(1,2) == "XX" then
    return false
  end
  local dec = prvKey:decrypt(message)
  print(dec)
  if dec:sub(3,3) == "#" then
    if dec:sub(1,2) ~= "XX" then
      return unfoldData(dec)
    end
  end
  return false
end

local function handle(...)
  local data = {...}
  print("'"..data[3].."'|'"..data[6].."'")
  sender = data[3]
  message = data[6]
  event.ignore("modem_message",handle)
  waiting = false
end

local function exit(_,_,char,_,player)
    if char == ("-"):byte() and player == "JKOC" then
        print("Stopping Client")
        event.ignore("key_up", exit)
        running = false
        mod.close()
    end
end

-- register event
event.listen("key_up",exit)
while running do
  message = ""
  sender = ""
  local tries = 0
--  term.clear()
  mod.open(localport)
  repeat
    tries = tries + 1
    waiting = true
    event.listen("modem_message",handle)
    event.timer(10,function() waiting = false end)
    mod.broadcast(80,"searchServer#"..localport)
    while waiting do
      os.sleep(0.5)
    end
    if not running then
      goto loopend
    end
    print("Sender: "..(sender ~= nil and sender or "nil"))
    print("Message: '"..(message ~= nil and message or "nil").."'")
  until (message ~= "" and message ~= nil) or tries == 10
  mod.close(localport)
  if message == "" or message == nil then
    print("Couldn't connect to the Auth-Server...")
    print("The Program will restart in 5 seconds...")
    os.sleep(5)
    goto loopend
  end
  server.id = sender
  server.port = 443
--  term.clear()
  print("Welcome to the Password Door Security System")
  print()
  print("Please enter Username and Password!")
  io.write("Username: ")
  local username = io.read()
  io.write("Password: ")
  local passhash = dat.sha256(text.trim(term.read(nil, false, nil, "*")))
  print("\n\nverifying credentials ... ")
  message = ""
  sender = ""
  tries = 0
  mod.open(localport)
  repeat
    tries = tries + 1
    waiting = true
    event.listen("modem_message",handle)
    event.timer(10,function() waiting = false end)
    sendData(false,"PK",pubKey:toString(),localport)
    while waiting do
      os.sleep(0.5)
    end
    print("'"..message.."'")
    if not running then
      goto loopend
    end
  until (message ~= "" and message ~= nil and sender == server.id) or tries == 2
  mod.close(localport)
  if message == "" or message == nil or sender ~= server.id then
    print("Couldn't connect to the Auth-Server...")
    print("The Program will restart in 5 seconds...")
    os.sleep(5)
    goto loopend
  end
  local data = recvData(message)
  if data[1] ~= "PK" then
    print("The Auth-Server couldn't send data...")
    print("The Program will restart in 5 seconds...")
    os.sleep(5)
    goto loopend
  end
  print(ser.serialize(data))
  server.key = classes.PublicKey.fromString(data[2])
  server.port = tonumber(data[3])
  message = ""
  sender = ""
  tries = 0
  mod.open(localport)
  repeat
    tries = tries + 1
    sendData(true,"VU",username,passhash)
    _,_,sender,_,_,message = event.pull(5,"modem_message")
  until (message ~= "" and message ~= nil and sender == server.id) or tries == 10
  mod.close(localport)
  if message == "" or message == nil or sender ~= server.id then
    print("Couldn't connect to the Auth-Server...")
    print("The Program will restart in 5 seconds...")
    os.sleep(5)
    goto loopend
  end
  local data = recvData(message)
  if data[1] ~= "UV" then
    print("The Auth-Server couldn't send data...")
    print("The Program will restart in 5 seconds...")
    os.sleep(5)
    goto loopend
  end
  if data[2] == "granted" then
    --
    -- Draw picture (need verify)
    --
    local oldBGColor = gpu.setBackground(0x33DD33)
    term.clear()
    gpu.setBackground(0x118811)
    local oldwidth,oldheight = gpu.setViewport(11,6)
    gpu.drawRectangle(2,2,9,4)
    gpu.setCursor(3,3)
    gpu.write("Access")
    gpu.setCursor(3,4)
    gpu.write("Granted")
    os.sleep(1)
    r.setOutput(side,true)
    os.sleep(5)
    r.setOutput(side,false)
    gpu.setBackground(oldBGColor)
    term.clear()
  end
  ::loopend::
end