gtHost

--[[      gtHost       ]]--
--[[      by Dog       ]]--
--[[ aka HydrantHunter ]]--
--[[ pastebin WzrdKVxm ]]--
local gtHver = "2.0.05"
--[[
Tested with/requires:
  - Minecraft 1.6.4+
  - ComputerCraft 1.63+
    - A Wireless Turtle (standard or advanced)
    - gtRemote running on an Advanced Wireless Pocket Computer

Special thanks to: Anavrins   (pbkdf2/sha256 hashing)
                   SquidDev   (AES encryption/decryption)
                   Alex Kloss (base64 encoder/decoder)
]]--
local tArgs = { ... }
--# CONFIGURATION
--# Default Settings
local termX, termY = term.getSize()
local thisCC = tostring(os.getComputerID())
local config = "/data/gtHostCfg"
local gtSettings = {
  name = "gtHost";
  note = "short note";
  color = "I";
  password = false;
  newColors = true;
  hashedPWs = false;
}
local loc = { x = "No GPS Fix", y = "No GPS Fix", z = "No GPS Fix" }
local gtInventory, unlockedClients = { }, { }
unlockedClients.count = 0
local netSide, slotContents = "none", "Unknown"
local client, gtHostKernel
local up, down, forward = false, false, false
local fuelAmount, coal, fuelPercent, turtleFuelLimit, selectedSlot = 0, 0, 0, 0, 1
local lockState, fuelState, dirCheck, redraw, gtRedstone, gtSuccess, shellCommand = false, false, false, false, false, false, false
--# Color Definitions
local white = colors.white
local black = colors.black
local silver = colors.lightGray
local gray = colors.gray
local brown = colors.brown
local yellow = colors.yellow
local orange = colors.orange
local red = colors.red
local magenta = colors.magenta
local purple = colors.purple
local blue = colors.blue
local sky = colors.lightBlue
local cyan = colors.cyan
local lime = colors.lime
local green = colors.green
if not term.isColor() then
  silver = colors.white
  gray = colors.black
  brown = colors.white
  yellow = colors.white
  orange = colors.white
  red = colors.white
  magenta = colors.white
  purple = colors.white
  green = colors.white
  blue = colors.black
  sky = colors.white
  cyan = colors.white
  lime = colors.white
  green = colors.white
end
local colorBurst = {
  P = { "Purple", purple };
  B = { "Blue", blue };
  S = { "Sky", sky };
  G = { "Green", green };
  R = { "Red", red };
  O = { "Orange", orange };
  N = { "Brown", brown };
  I = { "Silver", silver };
}
--# END CONFIGURATION

-- Lua 5.1+ base64 v3.0 (c) 2009 by Alex Kloss <[email protected]>
-- licensed under the terms of the LGPL2
-- http://lua-users.org/wiki/BaseSixtyFour
-- character table string
local b='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
-- encoding
function encode(data)
  return ((data:gsub('.', function(x)
    local r,b='',x:byte()
    for i=8,1,-1 do r=r..(b%2^i-b%2^(i-1)>0 and '1' or '0') end
    return r;
  end)..'0000'):gsub('%d%d%d?%d?%d?%d?', function(x)
    if (#x < 6) then return '' end
    local c=0
    for i=1,6 do c=c+(x:sub(i,i)=='1' and 2^(6-i) or 0) end
    return b:sub(c+1,c+1)
  end)..({ '', '==', '=' })[#data%3+1])
end
-- decoding
function decode(data)
  data = string.gsub(data, '[^'..b..'=]', '')
  return (data:gsub('.', function(x)
    if (x == '=') then return '' end
    local r,f='',(b:find(x)-1)
    for i=6,1,-1 do r=r..(f%2^i-f%2^(i-1)>0 and '1' or '0') end
    return r;
  end):gsub('%d%d%d?%d?%d?%d?%d?%d?', function(x)
    if (#x ~= 8) then return '' end
    local c=0
    for i=1,8 do c=c+(x:sub(i,i)=='1' and 2^(8-i) or 0) end
    return string.char(c)
  end))
end

-- AES Lua implementation by SquidDev
-- https://gist.github.com/SquidDev/86925e07cbabd70773e53d781bd8b2fe
local encrypt, decrypt
do
  local function _W(f) local e=setmetatable({}, {__index = _ENV or getfenv()}) if setfenv then setfenv(f, e) end return f(e) or e end
  local bit=_W(function(_ENV, ...)
  --[[
    This bit API is designed to cope with unsigned integers instead of normal integers
    To do this we add checks for overflows: (x > 2^31 ? x - 2 ^ 32 : x)
    These are written in long form because no constant folding.
  ]]
  local floor = math.floor
  local lshift, rshift

  rshift = function(a,disp)
    return floor(a % 4294967296 / 2^disp)
  end

  lshift = function(a,disp)
    return (a * 2^disp) % 4294967296
  end

  return {
    -- bit operations
    bnot = bit32 and bit32.bnot or bit.bnot,
    band = bit32 and bit32.band or bit.band,
    bor  = bit32 and bit32.bor or bit.bor,
    bxor = bit32 and bit32.bxor or bit.bxor,
    rshift = rshift,
    lshift = lshift,
  }
  end)

  local gf=_W(function(_ENV, ...)
  -- finite field with base 2 and modulo irreducible polynom x^8+x^4+x^3+x+1 = 0x11d
  local bxor = bit32 and bit32.bxor or bit.bxor
  local lshift = bit.lshift
  -- private data of gf
  local n = 0x100
  local ord = 0xff
  local irrPolynom = 0x11b
  local exp = {}
  local log = {}
  --
  -- add two polynoms (its simply xor)
  --
  local function add(operand1, operand2)
    return bxor(operand1,operand2)
  end
  --
  -- subtract two polynoms (same as addition)
  --
  local function sub(operand1, operand2)
    return bxor(operand1,operand2)
  end
  --
  -- inverts element
  -- a^(-1) = g^(order - log(a))
  --
  local function invert(operand)
    -- special case for 1
    if (operand == 1) then
      return 1
    end
    -- normal invert
    local exponent = ord - log[operand]
    return exp[exponent]
  end
  --
  -- multiply two elements using a logarithm table
  -- a*b = g^(log(a)+log(b))
  --
  local function mul(operand1, operand2)
    if (operand1 == 0 or operand2 == 0) then
      return 0
    end
    local exponent = log[operand1] + log[operand2]
    if (exponent >= ord) then
      exponent = exponent - ord
    end
    return exp[exponent]
  end
  --
  -- divide two elements
  -- a/b = g^(log(a)-log(b))
  --
  local function div(operand1, operand2)
    if (operand1 == 0)  then
      return 0
    end
    -- TODO: exception if operand2 == 0
    local exponent = log[operand1] - log[operand2]
    if (exponent < 0) then
      exponent = exponent + ord
    end
    return exp[exponent]
  end
  --
  -- print logarithmic table
  --
  local function printLog()
    for i = 1, n do
      print("log(", i-1, ")=", log[i-1])
    end
  end
  --
  -- print exponentiation table
  --
  local function printExp()
    for i = 1, n do
      print("exp(", i-1, ")=", exp[i-1])
    end
  end
  --
  -- calculate logarithmic and exponentiation table
  --
  local function initMulTable()
    local a = 1
    for i = 0,ord-1 do
      exp[i] = a
      log[a] = i
      -- multiply with generator x+1 -> left shift + 1
      a = bxor(lshift(a, 1), a)
      -- if a gets larger than order, reduce modulo irreducible polynom
      if a > ord then
        a = sub(a, irrPolynom)
      end
    end
  end

  initMulTable()

  return {
    add = add,
    sub = sub,
    invert = invert,
    mul = mul,
    div = div,
    printLog = printLog,
    printExp = printExp,
  }
  end)

  util=_W(function(_ENV, ...)
  -- Cache some bit operators
  local bxor = bit.bxor
  local rshift = bit.rshift
  local band = bit.band
  local lshift = bit.lshift
  local sleepCheckIn
  --
  -- calculate the parity of one byte
  --
  local function byteParity(byte)
    byte = bxor(byte, rshift(byte, 4))
    byte = bxor(byte, rshift(byte, 2))
    byte = bxor(byte, rshift(byte, 1))
    return band(byte, 1)
  end
  --
  -- get byte at position index
  --
  local function getByte(number, index)
    return index == 0 and band(number,0xff) or band(rshift(number, index*8),0xff)
  end
  --
  -- put number into int at position index
  --
  local function putByte(number, index)
    return index == 0 and band(number,0xff) or lshift(band(number,0xff),index*8)
  end
  --
  -- convert byte array to int array
  --
  local function bytesToInts(bytes, start, n)
    local ints = {}
    for i = 0, n - 1 do
      ints[i + 1] =
          putByte(bytes[start + (i*4)], 3) +
          putByte(bytes[start + (i*4) + 1], 2) +
          putByte(bytes[start + (i*4) + 2], 1) +
          putByte(bytes[start + (i*4) + 3], 0)
      if n % 10000 == 0 then sleepCheckIn() end
    end
    return ints
  end
  --
  -- convert int array to byte array
  --
  local function intsToBytes(ints, output, outputOffset, n)
    n = n or #ints
    for i = 0, n - 1 do
      for j = 0,3 do
        output[outputOffset + i*4 + (3 - j)] = getByte(ints[i + 1], j)
      end
      if n % 10000 == 0 then sleepCheckIn() end
    end
    return output
  end
  --
  -- convert bytes to hexString
  --
  local function bytesToHex(bytes)
    local hexBytes = ""
    for i,byte in ipairs(bytes) do
      hexBytes = hexBytes .. string.format("%02x ", byte)
    end
    return hexBytes
  end

  local function hexToBytes(bytes)
    local out = {}
    for i = 1, #bytes, 2 do
      out[#out + 1] = tonumber(bytes:sub(i, i + 1), 16)
    end
    return out
  end
  --
  -- convert data to hex string
  --
  local function toHexString(data)
    local type = type(data)
    if (type == "number") then
      return string.format("%08x",data)
    elseif (type == "table") then
      return bytesToHex(data)
    elseif (type == "string") then
      local bytes = {string.byte(data, 1, #data)}
      return bytesToHex(bytes)
    else
      return data
    end
  end

  local function padByteString(data)
    local dataLength = #data
    local random1 = math.random(0,255)
    local random2 = math.random(0,255)
    local prefix = string.char(random1,
      random2,
      random1,
      random2,
      getByte(dataLength, 3),
      getByte(dataLength, 2),
      getByte(dataLength, 1),
      getByte(dataLength, 0)
    )
    data = prefix .. data
    local padding, paddingLength = "", math.ceil(#data/16)*16 - #data
    for i=1,paddingLength do
      padding = padding .. string.char(math.random(0,255))
    end
    return data .. padding
  end

  local function properlyDecrypted(data)
    local random = {string.byte(data,1,4)}

    if (random[1] == random[3] and random[2] == random[4]) then
      return true
    end

    return false
  end

  local function unpadByteString(data)
    if (not properlyDecrypted(data)) then
      return nil
    end
    local dataLength = putByte(string.byte(data,5), 3)
             + putByte(string.byte(data,6), 2)
             + putByte(string.byte(data,7), 1)
             + putByte(string.byte(data,8), 0)
    return string.sub(data,9,8+dataLength)
  end

  local function xorIV(data, iv)
    for i = 1,16 do
      data[i] = bxor(data[i], iv[i])
    end
  end

  local function increment(data)
    local i = 16
    while true do
      local value = data[i] + 1
      if value >= 256 then
        data[i] = value - 256
        i = (i - 2) % 16 + 1
      else
        data[i] = value
        break
      end
    end
  end

  -- Called every encryption cycle
  local push, pull, time = os.queueEvent, coroutine.yield, os.time
  local oldTime = time()
  local function sleepCheckIn()
    local newTime = time()
    if newTime - oldTime >= 0.03 then -- (0.020 * 1.5)
      oldTime = newTime
      push("sleep")
      pull("sleep")
    end
  end

  local function getRandomData(bytes)
    local char, random, sleep, insert = string.char, math.random, sleepCheckIn, table.insert
    local result = {}
    for i=1,bytes do
      insert(result, random(0,255))
      if i % 10240 == 0 then sleep() end
    end
    return result
  end

  local function getRandomString(bytes)
    local char, random, sleep, insert = string.char, math.random, sleepCheckIn, table.insert
    local result = {}
    for i=1,bytes do
      insert(result, char(random(0,255)))
      if i % 10240 == 0 then sleep() end
    end
    return table.concat(result)
  end

  return {
    byteParity = byteParity,
    getByte = getByte,
    putByte = putByte,
    bytesToInts = bytesToInts,
    intsToBytes = intsToBytes,
    bytesToHex = bytesToHex,
    hexToBytes = hexToBytes,
    toHexString = toHexString,
    padByteString = padByteString,
    properlyDecrypted = properlyDecrypted,
    unpadByteString = unpadByteString,
    xorIV = xorIV,
    increment = increment,
    sleepCheckIn = sleepCheckIn,
    getRandomData = getRandomData,
    getRandomString = getRandomString,
  }
  end)

  aes=_W(function(_ENV, ...)
  -- Implementation of AES with nearly pure lua
  -- AES with lua is slow, really slow :-)
  local putByte = util.putByte
  local getByte = util.getByte
  -- some constants
  local ROUNDS = 'rounds'
  local KEY_TYPE = "type"
  local ENCRYPTION_KEY=1
  local DECRYPTION_KEY=2
  -- aes SBOX
  local SBox = {}
  local iSBox = {}
  -- aes tables
  local table0 = {}
  local table1 = {}
  local table2 = {}
  local table3 = {}
  local tableInv0 = {}
  local tableInv1 = {}
  local tableInv2 = {}
  local tableInv3 = {}
  -- round constants
  local rCon = {
    0x01000000,
    0x02000000,
    0x04000000,
    0x08000000,
    0x10000000,
    0x20000000,
    0x40000000,
    0x80000000,
    0x1b000000,
    0x36000000,
    0x6c000000,
    0xd8000000,
    0xab000000,
    0x4d000000,
    0x9a000000,
    0x2f000000,
  }
  --
  -- affine transformation for calculating the S-Box of AES
  --
  local function affinMap(byte)
    mask = 0xf8
    result = 0
    for i = 1,8 do
      result = bit.lshift(result,1)
      parity = util.byteParity(bit.band(byte,mask))
      result = result + parity
      -- simulate roll
      lastbit = bit.band(mask, 1)
      mask = bit.band(bit.rshift(mask, 1),0xff)
      mask = lastbit ~= 0 and bit.bor(mask, 0x80) or bit.band(mask, 0x7f)
    end
    return bit.bxor(result, 0x63)
  end
  --
  -- calculate S-Box and inverse S-Box of AES
  -- apply affine transformation to inverse in finite field 2^8
  --
  local function calcSBox()
    for i = 0, 255 do
      inverse = i ~= 0 and gf.invert(i) or i
      mapped = affinMap(inverse)
      SBox[i] = mapped
      iSBox[mapped] = i
    end
  end
  --
  -- Calculate round tables
  -- round tables are used to calculate shiftRow, MixColumn and SubBytes
  -- with 4 table lookups and 4 xor operations.
  --
  local function calcRoundTables()
    for x = 0,255 do
      byte = SBox[x]
      table0[x] = putByte(gf.mul(0x03, byte), 0)
                + putByte(             byte , 1)
                + putByte(             byte , 2)
                + putByte(gf.mul(0x02, byte), 3)
      table1[x] = putByte(             byte , 0)
                + putByte(             byte , 1)
                + putByte(gf.mul(0x02, byte), 2)
                + putByte(gf.mul(0x03, byte), 3)
      table2[x] = putByte(             byte , 0)
                + putByte(gf.mul(0x02, byte), 1)
                + putByte(gf.mul(0x03, byte), 2)
                + putByte(             byte , 3)
      table3[x] = putByte(gf.mul(0x02, byte), 0)
                + putByte(gf.mul(0x03, byte), 1)
                + putByte(             byte , 2)
                + putByte(             byte , 3)
    end
  end
  --
  -- Calculate inverse round tables
  -- does the inverse of the normal roundtables for the equivalent
  -- decryption algorithm.
  --
  local function calcInvRoundTables()
    for x = 0,255 do
      byte = iSBox[x]
      tableInv0[x] = putByte(gf.mul(0x0b, byte), 0)
                 + putByte(gf.mul(0x0d, byte), 1)
                 + putByte(gf.mul(0x09, byte), 2)
                 + putByte(gf.mul(0x0e, byte), 3)
      tableInv1[x] = putByte(gf.mul(0x0d, byte), 0)
                 + putByte(gf.mul(0x09, byte), 1)
                 + putByte(gf.mul(0x0e, byte), 2)
                 + putByte(gf.mul(0x0b, byte), 3)
      tableInv2[x] = putByte(gf.mul(0x09, byte), 0)
                 + putByte(gf.mul(0x0e, byte), 1)
                 + putByte(gf.mul(0x0b, byte), 2)
                 + putByte(gf.mul(0x0d, byte), 3)
      tableInv3[x] = putByte(gf.mul(0x0e, byte), 0)
                 + putByte(gf.mul(0x0b, byte), 1)
                 + putByte(gf.mul(0x0d, byte), 2)
                 + putByte(gf.mul(0x09, byte), 3)
    end
  end
  --
  -- rotate word: 0xaabbccdd gets 0xbbccddaa
  -- used for key schedule
  --
  local function rotWord(word)
    local tmp = bit.band(word,0xff000000)
    return (bit.lshift(word,8) + bit.rshift(tmp,24))
  end
  --
  -- replace all bytes in a word with the SBox.
  -- used for key schedule
  --
  local function subWord(word)
    return putByte(SBox[getByte(word,0)],0)
      + putByte(SBox[getByte(word,1)],1)
      + putByte(SBox[getByte(word,2)],2)
      + putByte(SBox[getByte(word,3)],3)
  end
  --
  -- generate key schedule for aes encryption
  --
  -- returns table with all round keys and
  -- the necessary number of rounds saved in [ROUNDS]
  --
  local function expandEncryptionKey(key)
    local keySchedule = {}
    local keyWords = math.floor(#key / 4)
    if ((keyWords ~= 4 and keyWords ~= 6 and keyWords ~= 8) or (keyWords * 4 ~= #key)) then
      error("Invalid key size: " .. tostring(keyWords))
      return nil
    end
    keySchedule[ROUNDS] = keyWords + 6
    keySchedule[KEY_TYPE] = ENCRYPTION_KEY
    for i = 0,keyWords - 1 do
      keySchedule[i] = putByte(key[i*4+1], 3)
               + putByte(key[i*4+2], 2)
               + putByte(key[i*4+3], 1)
               + putByte(key[i*4+4], 0)
    end
    for i = keyWords, (keySchedule[ROUNDS] + 1)*4 - 1 do
      local tmp = keySchedule[i-1]
      if ( i % keyWords == 0) then
        tmp = rotWord(tmp)
        tmp = subWord(tmp)
        local index = math.floor(i/keyWords)
        tmp = bit.bxor(tmp,rCon[index])
      elseif (keyWords > 6 and i % keyWords == 4) then
        tmp = subWord(tmp)
      end
      keySchedule[i] = bit.bxor(keySchedule[(i-keyWords)],tmp)
    end
    return keySchedule
  end
  --
  -- Inverse mix column
  -- used for key schedule of decryption key
  --
  local function invMixColumnOld(word)
    local b0 = getByte(word,3)
    local b1 = getByte(word,2)
    local b2 = getByte(word,1)
    local b3 = getByte(word,0)
    return putByte(gf.add(gf.add(gf.add(gf.mul(0x0b, b1),
                         gf.mul(0x0d, b2)),
                         gf.mul(0x09, b3)),
                         gf.mul(0x0e, b0)),3)
       + putByte(gf.add(gf.add(gf.add(gf.mul(0x0b, b2),
                         gf.mul(0x0d, b3)),
                         gf.mul(0x09, b0)),
                         gf.mul(0x0e, b1)),2)
       + putByte(gf.add(gf.add(gf.add(gf.mul(0x0b, b3),
                         gf.mul(0x0d, b0)),
                         gf.mul(0x09, b1)),
                         gf.mul(0x0e, b2)),1)
       + putByte(gf.add(gf.add(gf.add(gf.mul(0x0b, b0),
                         gf.mul(0x0d, b1)),
                         gf.mul(0x09, b2)),
                         gf.mul(0x0e, b3)),0)
  end
  --
  -- Optimized inverse mix column
  -- look at http://fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.311.pdf
  -- TODO: make it work
  --
  local function invMixColumn(word)
    local b0 = getByte(word,3)
    local b1 = getByte(word,2)
    local b2 = getByte(word,1)
    local b3 = getByte(word,0)
    local t = bit.bxor(b3,b2)
    local u = bit.bxor(b1,b0)
    local v = bit.bxor(t,u)
    v = bit.bxor(v,gf.mul(0x08,v))
    w = bit.bxor(v,gf.mul(0x04, bit.bxor(b2,b0)))
    v = bit.bxor(v,gf.mul(0x04, bit.bxor(b3,b1)))
    return putByte( bit.bxor(bit.bxor(b3,v), gf.mul(0x02, bit.bxor(b0,b3))), 0)
       + putByte( bit.bxor(bit.bxor(b2,w), gf.mul(0x02, t              )), 1)
       + putByte( bit.bxor(bit.bxor(b1,v), gf.mul(0x02, bit.bxor(b0,b3))), 2)
       + putByte( bit.bxor(bit.bxor(b0,w), gf.mul(0x02, u              )), 3)
  end
  --
  -- generate key schedule for aes decryption
  --
  -- uses key schedule for aes encryption and transforms each
  -- key by inverse mix column.
  --
  local function expandDecryptionKey(key)
    local keySchedule = expandEncryptionKey(key)
    if (keySchedule == nil) then
      return nil
    end
    keySchedule[KEY_TYPE] = DECRYPTION_KEY
    for i = 4, (keySchedule[ROUNDS] + 1)*4 - 5 do
      keySchedule[i] = invMixColumnOld(keySchedule[i])
    end
    return keySchedule
  end
  --
  -- xor round key to state
  --
  local function addRoundKey(state, key, round)
    for i = 0, 3 do
      state[i + 1] = bit.bxor(state[i + 1], key[round*4+i])
    end
  end
  --
  -- do encryption round (ShiftRow, SubBytes, MixColumn together)
  --
  local function doRound(origState, dstState)
    dstState[1] =  bit.bxor(bit.bxor(bit.bxor(
          table0[getByte(origState[1],3)],
          table1[getByte(origState[2],2)]),
          table2[getByte(origState[3],1)]),
          table3[getByte(origState[4],0)])
    dstState[2] =  bit.bxor(bit.bxor(bit.bxor(
          table0[getByte(origState[2],3)],
          table1[getByte(origState[3],2)]),
          table2[getByte(origState[4],1)]),
          table3[getByte(origState[1],0)])
    dstState[3] =  bit.bxor(bit.bxor(bit.bxor(
          table0[getByte(origState[3],3)],
          table1[getByte(origState[4],2)]),
          table2[getByte(origState[1],1)]),
          table3[getByte(origState[2],0)])
    dstState[4] =  bit.bxor(bit.bxor(bit.bxor(
          table0[getByte(origState[4],3)],
          table1[getByte(origState[1],2)]),
          table2[getByte(origState[2],1)]),
          table3[getByte(origState[3],0)])
  end
  --
  -- do last encryption round (ShiftRow and SubBytes)
  --
  local function doLastRound(origState, dstState)
    dstState[1] = putByte(SBox[getByte(origState[1],3)], 3)
          + putByte(SBox[getByte(origState[2],2)], 2)
          + putByte(SBox[getByte(origState[3],1)], 1)
          + putByte(SBox[getByte(origState[4],0)], 0)
    dstState[2] = putByte(SBox[getByte(origState[2],3)], 3)
          + putByte(SBox[getByte(origState[3],2)], 2)
          + putByte(SBox[getByte(origState[4],1)], 1)
          + putByte(SBox[getByte(origState[1],0)], 0)
    dstState[3] = putByte(SBox[getByte(origState[3],3)], 3)
          + putByte(SBox[getByte(origState[4],2)], 2)
          + putByte(SBox[getByte(origState[1],1)], 1)
          + putByte(SBox[getByte(origState[2],0)], 0)
    dstState[4] = putByte(SBox[getByte(origState[4],3)], 3)
          + putByte(SBox[getByte(origState[1],2)], 2)
          + putByte(SBox[getByte(origState[2],1)], 1)
          + putByte(SBox[getByte(origState[3],0)], 0)
  end
  --
  -- do decryption round
  --
  local function doInvRound(origState, dstState)
    dstState[1] =  bit.bxor(bit.bxor(bit.bxor(
          tableInv0[getByte(origState[1],3)],
          tableInv1[getByte(origState[4],2)]),
          tableInv2[getByte(origState[3],1)]),
          tableInv3[getByte(origState[2],0)])
    dstState[2] =  bit.bxor(bit.bxor(bit.bxor(
          tableInv0[getByte(origState[2],3)],
          tableInv1[getByte(origState[1],2)]),
          tableInv2[getByte(origState[4],1)]),
          tableInv3[getByte(origState[3],0)])
    dstState[3] =  bit.bxor(bit.bxor(bit.bxor(
          tableInv0[getByte(origState[3],3)],
          tableInv1[getByte(origState[2],2)]),
          tableInv2[getByte(origState[1],1)]),
          tableInv3[getByte(origState[4],0)])
    dstState[4] =  bit.bxor(bit.bxor(bit.bxor(
          tableInv0[getByte(origState[4],3)],
          tableInv1[getByte(origState[3],2)]),
          tableInv2[getByte(origState[2],1)]),
          tableInv3[getByte(origState[1],0)])
  end
  --
  -- do last decryption round
  --
  local function doInvLastRound(origState, dstState)
    dstState[1] = putByte(iSBox[getByte(origState[1],3)], 3)
          + putByte(iSBox[getByte(origState[4],2)], 2)
          + putByte(iSBox[getByte(origState[3],1)], 1)
          + putByte(iSBox[getByte(origState[2],0)], 0)
    dstState[2] = putByte(iSBox[getByte(origState[2],3)], 3)
          + putByte(iSBox[getByte(origState[1],2)], 2)
          + putByte(iSBox[getByte(origState[4],1)], 1)
          + putByte(iSBox[getByte(origState[3],0)], 0)
    dstState[3] = putByte(iSBox[getByte(origState[3],3)], 3)
          + putByte(iSBox[getByte(origState[2],2)], 2)
          + putByte(iSBox[getByte(origState[1],1)], 1)
          + putByte(iSBox[getByte(origState[4],0)], 0)
    dstState[4] = putByte(iSBox[getByte(origState[4],3)], 3)
          + putByte(iSBox[getByte(origState[3],2)], 2)
          + putByte(iSBox[getByte(origState[2],1)], 1)
          + putByte(iSBox[getByte(origState[1],0)], 0)
  end
  --
  -- encrypts 16 Bytes
  -- key           encryption key schedule
  -- input         array with input data
  -- inputOffset   start index for input
  -- output        array for encrypted data
  -- outputOffset  start index for output
  --
  local function encrypt(key, input, inputOffset, output, outputOffset)
    --default parameters
    inputOffset = inputOffset or 1
    output = output or {}
    outputOffset = outputOffset or 1
    local state = {}
    local tmpState = {}
    if (key[KEY_TYPE] ~= ENCRYPTION_KEY) then
      error("No encryption key: " .. tostring(key[KEY_TYPE]) .. ", expected " .. ENCRYPTION_KEY)
      return
    end
    state = util.bytesToInts(input, inputOffset, 4)
    addRoundKey(state, key, 0)
    local round = 1
    while (round < key[ROUNDS] - 1) do
      -- do a double round to save temporary assignments
      doRound(state, tmpState)
      addRoundKey(tmpState, key, round)
      round = round + 1
      doRound(tmpState, state)
      addRoundKey(state, key, round)
      round = round + 1
    end
    doRound(state, tmpState)
    addRoundKey(tmpState, key, round)
    round = round +1
    doLastRound(tmpState, state)
    addRoundKey(state, key, round)
    util.sleepCheckIn()
    return util.intsToBytes(state, output, outputOffset)
  end
  --
  -- decrypt 16 bytes
  -- key           decryption key schedule
  -- input         array with input data
  -- inputOffset   start index for input
  -- output        array for decrypted data
  -- outputOffset  start index for output
  ---
  local function decrypt(key, input, inputOffset, output, outputOffset)
    -- default arguments
    inputOffset = inputOffset or 1
    output = output or {}
    outputOffset = outputOffset or 1
    local state = {}
    local tmpState = {}
    if (key[KEY_TYPE] ~= DECRYPTION_KEY) then
      error("No decryption key: " .. tostring(key[KEY_TYPE]))
      return
    end
    state = util.bytesToInts(input, inputOffset, 4)
    addRoundKey(state, key, key[ROUNDS])
    local round = key[ROUNDS] - 1
    while (round > 2) do
      -- do a double round to save temporary assignments
      doInvRound(state, tmpState)
      addRoundKey(tmpState, key, round)
      round = round - 1
      doInvRound(tmpState, state)
      addRoundKey(state, key, round)
      round = round - 1
    end
    doInvRound(state, tmpState)
    addRoundKey(tmpState, key, round)
    round = round - 1
    doInvLastRound(tmpState, state)
    addRoundKey(state, key, round)
    util.sleepCheckIn()
    return util.intsToBytes(state, output, outputOffset)
  end

  -- calculate all tables when loading this file
  calcSBox()
  calcRoundTables()
  calcInvRoundTables()

  return {
    ROUNDS = ROUNDS,
    KEY_TYPE = KEY_TYPE,
    ENCRYPTION_KEY = ENCRYPTION_KEY,
    DECRYPTION_KEY = DECRYPTION_KEY,
    expandEncryptionKey = expandEncryptionKey,
    expandDecryptionKey = expandDecryptionKey,
    encrypt = encrypt,
    decrypt = decrypt,
  }
  end)

  local buffer=_W(function(_ENV, ...)
  local function new ()
    return {}
  end

  local function addString (stack, s)
    table.insert(stack, s)
  end

  local function toString (stack)
    return table.concat(stack)
  end

  return {
    new = new,
    addString = addString,
    toString = toString,
  }
  end)

  ciphermode=_W(function(_ENV, ...)
  local public = {}
  --
  -- Encrypt strings
  -- key - byte array with key
  -- string - string to encrypt
  -- modefunction - function for cipher mode to use
  --
  local random, unpack = math.random, unpack or table.unpack
  function public.encryptString(key, data, modeFunction, iv)
    if iv then
      local ivCopy = {}
      for i = 1, 16 do ivCopy[i] = iv[i] end
      iv = ivCopy
    else
      iv = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
    end
    local keySched = aes.expandEncryptionKey(key)
    local encryptedData = buffer.new()
    for i = 1, #data/16 do
      local offset = (i-1)*16 + 1
      local byteData = {string.byte(data,offset,offset +15)}
      iv = modeFunction(keySched, byteData, iv)
      buffer.addString(encryptedData, string.char(unpack(byteData)))
    end
    return buffer.toString(encryptedData)
  end
  --
  -- the following 4 functions can be used as
  -- modefunction for encryptString
  --
  -- Electronic code book mode encrypt function
  function public.encryptECB(keySched, byteData, iv)
    aes.encrypt(keySched, byteData, 1, byteData, 1)
  end

  -- Cipher block chaining mode encrypt function
  function public.encryptCBC(keySched, byteData, iv)
    util.xorIV(byteData, iv)
    aes.encrypt(keySched, byteData, 1, byteData, 1)
    return byteData
  end

  -- Output feedback mode encrypt function
  function public.encryptOFB(keySched, byteData, iv)
    aes.encrypt(keySched, iv, 1, iv, 1)
    util.xorIV(byteData, iv)
    return iv
  end

  -- Cipher feedback mode encrypt function
  function public.encryptCFB(keySched, byteData, iv)
    aes.encrypt(keySched, iv, 1, iv, 1)
    util.xorIV(byteData, iv)
    return byteData
  end

  function public.encryptCTR(keySched, byteData, iv)
    local nextIV = {}
    for j = 1, 16 do nextIV[j] = iv[j] end
    aes.encrypt(keySched, iv, 1, iv, 1)
    util.xorIV(byteData, iv)
    util.increment(nextIV)
    return nextIV
  end
  --
  -- Decrypt strings
  -- key - byte array with key
  -- string - string to decrypt
  -- modefunction - function for cipher mode to use
  --
  function public.decryptString(key, data, modeFunction, iv)
    if iv then
      local ivCopy = {}
      for i = 1, 16 do ivCopy[i] = iv[i] end
      iv = ivCopy
    else
      iv = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
    end
    local keySched
    if modeFunction == public.decryptOFB or modeFunction == public.decryptCFB or modeFunction == public.decryptCTR then
      keySched = aes.expandEncryptionKey(key)
    else
      keySched = aes.expandDecryptionKey(key)
    end
    local decryptedData = buffer.new()
    for i = 1, #data/16 do
      local offset = (i-1)*16 + 1
      local byteData = {string.byte(data,offset,offset +15)}
      iv = modeFunction(keySched, byteData, iv)
      buffer.addString(decryptedData, string.char(unpack(byteData)))
    end
    return buffer.toString(decryptedData)
  end
  --
  -- the following 4 functions can be used as
  -- modefunction for decryptString
  --
  -- Electronic code book mode decrypt function
  function public.decryptECB(keySched, byteData, iv)
    aes.decrypt(keySched, byteData, 1, byteData, 1)
    return iv
  end

  -- Cipher block chaining mode decrypt function
  function public.decryptCBC(keySched, byteData, iv)
    local nextIV = {}
    for j = 1, 16 do nextIV[j] = byteData[j] end
    aes.decrypt(keySched, byteData, 1, byteData, 1)
    util.xorIV(byteData, iv)
    return nextIV
  end

  -- Output feedback mode decrypt function
  function public.decryptOFB(keySched, byteData, iv)
    aes.encrypt(keySched, iv, 1, iv, 1)
    util.xorIV(byteData, iv)
    return iv
  end

  -- Cipher feedback mode decrypt function
  function public.decryptCFB(keySched, byteData, iv)
    local nextIV = {}
    for j = 1, 16 do nextIV[j] = byteData[j] end
    aes.encrypt(keySched, iv, 1, iv, 1)
    util.xorIV(byteData, iv)
    return nextIV
  end

  public.decryptCTR = public.encryptCTR
  return public
  end)

  -- Simple API for encrypting strings.
  --
  AES128 = 16
  AES192 = 24
  AES256 = 32
  ECBMODE = 1
  CBCMODE = 2
  OFBMODE = 3
  CFBMODE = 4
  CTRMODE = 4

  local function pwToKey(password, keyLength, iv)
    local padLength = keyLength
    if (keyLength == AES192) then
      padLength = 32
    end
    if (padLength > #password) then
      local postfix = ""
      for i = 1,padLength - #password do
        postfix = postfix .. string.char(0)
      end
      password = password .. postfix
    else
      password = string.sub(password, 1, padLength)
    end
    local pwBytes = {string.byte(password,1,#password)}
    password = ciphermode.encryptString(pwBytes, password, ciphermode.encryptCBC, iv)
    password = string.sub(password, 1, keyLength)
    return {string.byte(password,1,#password)}
  end
  --
  -- Encrypts string data with password password.
  -- password  - the encryption key is generated from this string
  -- data      - string to encrypt (must not be too large)
  -- keyLength - length of aes key: 128(default), 192 or 256 Bit
  -- mode      - mode of encryption: ecb, cbc(default), ofb, cfb
  --
  -- mode and keyLength must be the same for encryption and decryption.
  --
  function encrypt(password, data, keyLength, mode, iv)
    assert(password ~= nil, "Empty password.")
    assert(data ~= nil, "Empty data.")
    local mode = mode or CBCMODE
    local keyLength = keyLength or AES128
    local key = pwToKey(password, keyLength, iv)
    local paddedData = util.padByteString(data)
    if mode == ECBMODE then
      return ciphermode.encryptString(key, paddedData, ciphermode.encryptECB, iv)
    elseif mode == CBCMODE then
      return ciphermode.encryptString(key, paddedData, ciphermode.encryptCBC, iv)
    elseif mode == OFBMODE then
      return ciphermode.encryptString(key, paddedData, ciphermode.encryptOFB, iv)
    elseif mode == CFBMODE then
      return ciphermode.encryptString(key, paddedData, ciphermode.encryptCFB, iv)
    elseif mode == CTRMODE then
      return ciphermode.encryptString(key, paddedData, ciphermode.encryptCTR, iv)
    else
      error("Unknown mode", 2)
    end
  end
  --
  -- Decrypts string data with password password.
  -- password  - the decryption key is generated from this string
  -- data      - string to encrypt
  -- keyLength - length of aes key: 128(default), 192 or 256 Bit
  -- mode      - mode of decryption: ecb, cbc(default), ofb, cfb
  --
  -- mode and keyLength must be the same for encryption and decryption.
  --
  function decrypt(password, data, keyLength, mode, iv)
    local mode = mode or CBCMODE
    local keyLength = keyLength or AES128
    local key = pwToKey(password, keyLength, iv)
    local plain
    if mode == ECBMODE then
      plain = ciphermode.decryptString(key, data, ciphermode.decryptECB, iv)
    elseif mode == CBCMODE then
      plain = ciphermode.decryptString(key, data, ciphermode.decryptCBC, iv)
    elseif mode == OFBMODE then
      plain = ciphermode.decryptString(key, data, ciphermode.decryptOFB, iv)
    elseif mode == CFBMODE then
      plain = ciphermode.decryptString(key, data, ciphermode.decryptCFB, iv)
    elseif mode == CTRMODE then
      plain = ciphermode.decryptString(key, data, ciphermode.decryptCTR, iv)
    else
      error("Unknown mode", 2)
    end
    result = util.unpadByteString(plain)
    if (result == nil) then
      return nil
    end
    return result
  end
end

-- SHA-256, HMAC and PBKDF2 functions in ComputerCraft
-- By Anavrins
-- For help and details, you can PM me on the CC forums
-- http://www.computercraft.info/forums2/index.php?/user/12870-anavrins
-- Pastebin: http://pastebin.com/6UV4qfNF
-- You may use this code in your projects without asking me, as long as credit is given and this header is kept intact
local digest, hmac, pbkdf2
do
  local mod32 = 2^32
  local sha_hashlen = 32
  local sha_blocksize = 64
  local band    = bit32 and bit32.band or bit.band
  local bnot    = bit32 and bit32.bnot or bit.bnot
  local bxor    = bit32 and bit32.bxor or bit.bxor
  local blshift = bit32 and bit32.lshift or bit.blshift
  local upack   = unpack

  local function rrotate(n, b)
    local s = n/(2^b)
    local f = s%1
    return (s-f) + f*mod32
  end

  local function brshift(int, by) -- Thanks bit32 for bad rshift
    local s = int / (2^by)
    return s - s%1
  end

  local H = {
    0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
    0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19,
  }

  local K = {
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
    0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
    0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
    0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
    0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
    0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
  }

  local function counter(incr)
    local t1, t2 = 0, 0
    if 0xFFFFFFFF - t1 < incr then
      t2 = t2 + 1
      t1 = incr - (0xFFFFFFFF - t1) - 1
    else t1 = t1 + incr
    end
    return t2, t1
  end

  local function BE_toInt(bs, i)
    return blshift((bs[i] or 0), 24) + blshift((bs[i+1] or 0), 16) + blshift((bs[i+2] or 0), 8) + (bs[i+3] or 0)
  end

  local function preprocess(data)
    local len = #data
    local proc = {}
    data[#data+1] = 0x80
    while #data%64~=56 do data[#data+1] = 0 end
    local blocks = math.ceil(#data/64)
    for i = 1, blocks do
      proc[i] = {}
      for j = 1, 16 do
        proc[i][j] = BE_toInt(data, 1+((i-1)*64)+((j-1)*4))
      end
    end
    proc[blocks][15], proc[blocks][16] = counter(len*8)
    return proc
  end

  local function digestblock(w, C)
    for j = 17, 64 do
      local v = w[j-15]
      local s0 = bxor(bxor(rrotate(w[j-15], 7), rrotate(w[j-15], 18)), brshift(w[j-15], 3))
      local s1 = bxor(bxor(rrotate(w[j-2], 17), rrotate(w[j-2], 19)), brshift(w[j-2], 10))
      w[j] = (w[j-16] + s0 + w[j-7] + s1)%mod32
    end
    local a, b, c, d, e, f, g, h = upack(C)
    for j = 1, 64 do
      local S1 = bxor(bxor(rrotate(e, 6), rrotate(e, 11)), rrotate(e, 25))
      local ch = bxor(band(e, f), band(bnot(e), g))
      local temp1 = (h + S1 + ch + K[j] + w[j])%mod32
      local S0 = bxor(bxor(rrotate(a, 2), rrotate(a, 13)), rrotate(a, 22))
      local maj = bxor(bxor(band(a, b), band(a, c)), band(b, c))
      local temp2 = (S0 + maj)%mod32
      h, g, f, e, d, c, b, a = g, f, e, (d+temp1)%mod32, c, b, a, (temp1+temp2)%mod32
    end
    C[1] = (C[1] + a)%mod32
    C[2] = (C[2] + b)%mod32
    C[3] = (C[3] + c)%mod32
    C[4] = (C[4] + d)%mod32
    C[5] = (C[5] + e)%mod32
    C[6] = (C[6] + f)%mod32
    C[7] = (C[7] + g)%mod32
    C[8] = (C[8] + h)%mod32
    return C
  end

  local mt = {
    __tostring = function(a) return string.char(unpack(a)) end,
    __index = {
      toHex = function(self, s) return ("%02x"):rep(#self):format(unpack(self)) end,
      isEqual = function(self, t)
        if type(t) ~= "table" then return false end
        if #self ~= #t then return false end
        local ret = 0
        for i = 1, #self do
          ret = bit32.bor(ret, bxor(self[i], t[i]))
        end
        return ret == 0
      end
    }
  }

  local function toBytes(t, n)
    local b = {}
    for i = 1, n do
      b[(i-1)*4+1] = band(brshift(band(t[i], 0xFF000000), 24), 0xFF)
      b[(i-1)*4+2] = band(brshift(band(t[i], 0xFF0000), 16), 0xFF)
      b[(i-1)*4+3] = band(brshift(band(t[i], 0xFF00), 8), 0xFF)
      b[(i-1)*4+4] = band(t[i], 0xFF)
    end
    return setmetatable(b, mt)
  end

  digest = function(data)
    data = data or ""
    data = type(data) == "string" and {data:byte(1,-1)} or data
    data = preprocess(data)
    local C = {upack(H)}
    for i = 1, #data do C = digestblock(data[i], C) end
    return toBytes(C, 8)
  end

  hmac = function(data, key)
    local data = type(data) == "table" and {upack(data)} or {tostring(data):byte(1,-1)}
    local key = type(key) == "table" and {upack(key)} or {tostring(key):byte(1,-1)}
    local blocksize = sha_blocksize
    key = #key > blocksize and digest(key) or key
    local ipad = {}
    local opad = {}
    local padded_key = {}
    for i = 1, blocksize do
      ipad[i] = bxor(0x36, key[i] or 0)
      opad[i] = bxor(0x5C, key[i] or 0)
    end
    for i = 1, #data do
      ipad[blocksize+i] = data[i]
    end
    ipad = digest(ipad)
    for i = 1, blocksize do
      padded_key[i] = opad[i]
      padded_key[blocksize+i] = ipad[i]
    end
    return digest(padded_key)
  end

  pbkdf2 = function(pass, salt, iter, dklen)
    local out = {}
    local hashlen = sha_hashlen
    local block = 1
    dklen = dklen or 32
    while dklen > 0 do
      local ikey = {}
      local isalt = type(salt) == "table" and {upack(salt)} or {tostring(salt):byte(1,-1)}
      local clen = dklen > hashlen and hashlen or dklen
      local iCount = #isalt
      isalt[iCount+1] = band(brshift(band(block, 0xFF000000), 24), 0xFF)
      isalt[iCount+2] = band(brshift(band(block, 0xFF0000), 16), 0xFF)
      isalt[iCount+3] = band(brshift(band(block, 0xFF00), 8), 0xFF)
      isalt[iCount+4] = band(block, 0xFF)
      for j = 1, iter do
        isalt = hmac(isalt, pass)
        for k = 1, clen do ikey[k] = bxor(isalt[k], ikey[k] or 0) end
        if j % 200 == 0 then os.queueEvent("PBKDF2", j) coroutine.yield("PBKDF2") end
      end
      dklen = dklen - clen
      block = block+1
      for k = 1, clen do out[#out+1] = ikey[k] end
    end
    return setmetatable(out, mt)
  end
end

local function getFuelLevel()
  fuelAmount, fuelPercent, coal, fuelState = turtle.getFuelLevel(), 0, 0, false
  local bFuelAmount = type(fuelAmount) == "string"
  if bFuelAmount or fuelAmount > 0 then
    fuelPercent = bFuelAmount and 101 or math.floor((fuelAmount / turtleFuelLimit) * 100)
    coal = bFuelAmount and 0 or math.floor(fuelAmount / 80)
    fuelState = true
  end
  return true
end

local function getSlotContents()
  local contents = turtle.getItemDetail(selectedSlot)
  slotContents = contents and contents.name:sub(contents.name:find(":") + 1, contents.name:find(":") + 18) or "<empty>"
end

local function inventorySlots()
  for i = 1, 16 do
    gtInventory[i] = { }
    gtInventory[i].count = turtle.getItemCount(i)
    if gtInventory[i].count > 0 then
      turtle.select(i)
      selectedSlot = i
      gtInventory[i].isFuel = turtle.refuel(0)
    else
      gtInventory[i].isFuel = false
    end
  end
  if _CC_VERSION or _HOST then getSlotContents() end
end

local function saveData()
  local turtleConfig = fs.open(config, "w") or error("saveData(): Cannot open " .. config .. " for writing", 0)
  turtleConfig.write(textutils.serialize(gtSettings))
  turtleConfig.close()
end

local function clearTerm()
  term.setBackgroundColor(black)
  term.setTextColor(white)
  term.clear()
  term.setCursorPos(1, 1)
end

local function drawElement(x, y, w, h, txtColor, bgColor, text)
  text = text and tostring(text) or ""
  local txtLen = #text
  w = math.max(w, txtLen)
  local spacer = (w - txtLen) / 2
  local txtLine = string.rep(" ", math.floor(spacer)) .. text .. string.rep(" ", math.ceil(spacer))
  if txtColor then term.setTextColor(txtColor) end
  if bgColor then term.setBackgroundColor(bgColor) end
  if h == 1 then
    term.setCursorPos(x, y)
    term.write(txtLine)
  else
    local line, textRow = string.rep(" ", w), y + math.floor(h / 2)
    for i = y, y + h - 1 do
      term.setCursorPos(x, i)
      term.write(i == textRow and txtLine or line) --# Draw one line of the 'element' (box/rectangle/line-seg)
    end
  end
end

local function shutDown()
  rednet.unhost("gtRemote", gtSettings.name .. thisCC)
  if rednet.isOpen(netSide) then rednet.close(netSide) end
  term.write("gtHost is OFFLINE")
  term.setCursorPos(1, 5)
end

local function foregroundShell()
  clearTerm()
  if fs.exists(tArgs[1]) then
    local unpack = unpack or table.unpack
      shell.run(unpack(tArgs))
    clearTerm()
  else
    term.write(tArgs[1] .. " missing")
    term.setCursorPos(1, 3)
  end
  shutDown()
end

local function charInput()
  local _, char
  while true do
    _, char = os.pullEvent("char")
    if char:lower() == "q" and not shellCommand then
      clearTerm()
      return shutDown()
    end
  end
end

do
  local validActions = {
    move = {         --# Movement
      forward = function() return turtle.forward() end;
      back = function() return turtle.back() end;
      left = function() return turtle.turnLeft() end;
      right = function() return turtle.turnRight() end;
      up = function() return turtle.up() end;
      down = function() return turtle.down() end;
    };
    atk = true;      --# Action - attack
    dig = {          --# Action - break
      Forward = function() return turtle.dig() end;
      Up = function() return turtle.digUp() end;
      Down = function() return turtle.digDown() end;
    };
    dcToggle = true; --# Toggle obstacle check
    sCmd = true;     --# Shell command
    put = {          --# Action - place
      Forward = function() return turtle.place() end;
      Up = function() return turtle.placeUp() end;
      Down = function() return turtle.placeDown() end;
    };
    inv = true;      --# Refresh inventory
    sel = true;      --# Select slot (slot)
    eqp = {          --# Equip item in slot (side)
      left = function() return turtle.equipLeft() end;
      right = function() return turtle.equipRight() end;
    };
    rds = true;      --# Toggle redstone signal
    name = true;     --# change name
    note = true;     --# change description
    color = true;    --# change color
    gpsLoc = true;   --# GPS fix
    refuel = true;   --# refuel
    gtrQRY = true;   --# QRY
    lock = true;     --# lock turtle
    unlock = true;   --# unlock turtle
  }

  local function checkDirections()
    up = turtle.detectUp()
    down = turtle.detectDown()
    forward = turtle.detect()
  end

  local function doAction(command, action)
    if lockState and command ~= "gtrQRY" and command ~= "unlock" then return false end
    local tAction = false
    if command == "move" then
      if validActions.move[action] then tAction = validActions.move[action]() end
      if tAction then
        if dirCheck then checkDirections() end
        if gtRedstone then
          rs.setOutput("front", false)
          gtRedstone = false
        end
        if action ~= "left" and action ~= "right" then getFuelLevel() end
      end
    elseif command == "dig" then
      if validActions.dig[action] then tAction = validActions.dig[action]() end
      if tAction then
        inventorySlots()
        if dirCheck then checkDirections() end
      end
    elseif command == "atk" then
      tAction = turtle.attack()
      if tAction then
        turtle.suck()
        inventorySlots()
      end
    elseif command == "dcToggle" then
      dirCheck = action
      if dirCheck then
        checkDirections()
      else
        up, down, forward = false, false, false
      end
      tAction = true
    elseif command == "sCmd" then
      if tArgs[1] or shellCommand then return false end
      shellCommand = true
      clearTerm()
      tAction = shell.run(action)
      shellCommand, redraw = false, true
      if tAction then
        gtRedstone = rs.getOutput("front")
        getFuelLevel()
        inventorySlots()
        if dirCheck then checkDirections() end
      end
    elseif command == "put" then
      if validActions.put[action] then
        tAction = validActions.put[action]() --# Place
      else
        tAction = turtle.place(action) --# Engrave sign
      end
      if tAction then
        inventorySlots()
        if dirCheck then checkDirections() end
      end
    elseif command == "inv" then
      inventorySlots()
      tAction = true
    elseif command == "sel" and type(action) == "number" and action > 0 and action < 17 then
      tAction = turtle.select(action) --# select user chosen slot
      selectedSlot = tAction and action or selectedSlot
      if _CC_VERSION or _HOST then getSlotContents() end
    elseif command == "rds" then
      rs.setOutput("front", action)
      gtRedstone = action
      tAction = true
    elseif command == "gtrQRY" then
      if action == "Full" then
        gtRedstone = rs.getOutput("front")
        getFuelLevel()
        inventorySlots()
        if dirCheck then checkDirections() end
      end
      tAction = true
    elseif command == "name" or command == "note" then
      gtSettings[command] = action
      if command == "name" then os.setComputerLabel(action) redraw = true end
      saveData()
      tAction = true
    elseif command == "color" then
      if colorBurst[action] then
        gtSettings.color = action
        saveData()
      end
      tAction = gtSettings.color == action
    elseif command == "refuel" and gtInventory[selectedSlot].isFuel then
      tAction = turtle.refuel(action)
      getFuelLevel()
      gtInventory[selectedSlot].count = turtle.getItemCount(selectedSlot)
      if gtInventory[selectedSlot].count == 0 then gtInventory[selectedSlot].isFuel = false slotContents = "<emtpy>" end
    elseif command == "eqp" then
      if (action ~= "right" and action ~= "left") or (action == netSide) then return false end
      tAction = validActions.eqp[action]()
      gtInventory[selectedSlot].count = turtle.getItemCount(selectedSlot)
      if _CC_VERSION or _HOST then getSlotContents() end
    elseif command == "gpsLoc" then
      loc.x, loc.y, loc.z = gps.locate(2)
      if not loc.x then
        loc.x, loc.y, loc.z = "No GPS Fix", "No GPS Fix", "No GPS Fix"
      end
      tAction = loc.x ~= "No GPS Fix"
    elseif command == "lock" then
      if not gtSettings.password or not unlockedClients[client] then return false end
      lockState = true
      unlockedClients[client] = nil
      unlockedClients.count = math.max(0, unlockedClients.count - 1)
      tAction = true
    elseif command == "unlock" then
      if not lockState then return false end
      if gtSettings.password and gtSettings.password == action then
        lockState = false
        unlockedClients[client] = true
        unlockedClients.count = unlockedClients.count + 1
        tAction = true
      end
    end
    return tAction
  end

  local function netReceive()
    local success, complete, newCmdData, encryptedData, decodedData, decryptedData, encKey, id = false, false, { }
    while true do
      if not rednet.isOpen(netSide) then rednet.open(netSide) end
      id, encryptedData = rednet.receive("gtRemote")
      complete, newCmdData = false, { }
      if type(encryptedData) == "string" then
        success, decodedData = pcall(decode, encryptedData)
        if success and type(decodedData) == "string" then
          encKey = thisCC .. "gt!Remote" .. tostring(id)
          success, decryptedData = pcall(decrypt, encKey, decodedData)
          if success and type(decryptedData) == "string" then
            success, newCmdData = pcall(textutils.unserialize, decryptedData)
            if success and type(newCmdData) == "table" and newCmdData.program and newCmdData.program == "gtRemote" and newCmdData.cc and newCmdData.cc == id then
              complete = true
            end
          else
            encKey = tostring(id) .. "gt!Remote_Broadcast" .. tostring(id)
            success, decryptedData = pcall(decrypt, encKey, decodedData)
            if success and type(decryptedData) == "string" then
              success, newCmdData = pcall(textutils.unserialize, decryptedData)
              if success and type(newCmdData) == "table" and newCmdData.program and newCmdData.program == "gtRemote" and newCmdData.cc and newCmdData.cc == id then
                complete = true
              end
            end
          end
        end
      end
      if complete then
        client = id
        if validActions[newCmdData.cmd] then
          lockState = true
          if gtSettings.password then
            if unlockedClients[client] then lockState = false end
          else
            lockState = false
          end
          return doAction(newCmdData.cmd, newCmdData.action)
        end
      end
      return false
    end
  end

  local function reportStatus(successState)
    gtSuccess = successState
    local dataPack = textutils.serialize({
      program = "gtRemoteHost";
      cc = tonumber(thisCC);
      name = gtSettings.name;
      note = gtSettings.note;
      color = gtSettings.color;
      redstone = gtRedstone;
      lockState = lockState;
      fuelState = fuelState;
      fuelAmount = fuelAmount;
      fuelPercent = fuelPercent;
      coal = coal;
      slot = selectedSlot;
      contents = slotContents;
      quietCount = 0;
      loc = { x = loc.x, y = loc.y, z = loc.z };
      inv = gtInventory;
      up = up;
      down = down;
      forward = forward;
      dirCheck = dirCheck;
    })
    local encKey = tostring(client) .. "gt!Remote" .. thisCC
    local encryptedData = encode(encrypt(encKey, dataPack))
    if not rednet.isOpen(netSide) then rednet.open(netSide) end
    rednet.send(client, encryptedData, "gtRemote")
  end

  local function staticTermScreen()
    local titleText = gtSettings.name .. " / # " .. thisCC .. " / " .. "gtHost " .. gtHver
    term.setBackgroundColor(black)
    term.clear()
    drawElement(1, 1, termX, 1, white, blue, titleText)
    drawElement(2, 3, 1, 1, gray, black, "Name:")
    drawElement(2, 4, 1, 1, nil, nil, "Description:")
    drawElement(2, 5, 1, 1, nil, nil, "Assigned Color:")
    drawElement(2, 7, 1, 1, nil, nil, "Fuel:")
    if fuelPercent < 101 then drawElement(2, 8, 1, 1, nil, nil, "Coal equiv:") end
    drawElement(2, 10, 1, 1, nil, nil, "Redstone output:")
    if gtSettings.password then drawElement(2, 11, 1, 1, nil, nil, "Unlocked clients:") end
    drawElement(2, termY - 1, 1, 1, nil, nil, "Last Action Success:")
  end

  gtHostKernel = function()
    local sFuelLimit, sFuelAmount, fuelColor = tostring(math.floor(turtleFuelLimit / 1000))
    while true do
      if not tArgs[1] and not shellCommand then
        if redraw then
          staticTermScreen()
          redraw = false
        end
        drawElement(18, 3, 1, 1, white, black, gtSettings.name)
        drawElement(18, 4, 1, 1, silver, nil, gtSettings.note .. string.rep(" ", 24 - #gtSettings.note))
        drawElement(18, 5, 1, 1, colorBurst[gtSettings.color][2] or red, nil, (colorBurst[gtSettings.color][1] or "Error") .. "     ")
        fuelColor = fuelPercent > 49 and green or orange
        drawElement(14, 7, 1, 1, fuelPercent < 10 and red or fuelColor, nil, fuelPercent < 101 and tostring(fuelPercent) or "Unlimited")
        if fuelPercent < 101 then
          term.setTextColor(silver)
          term.write("%   ")
          sFuelAmount = fuelAmount >= 1000 and tostring(math.floor(fuelAmount / 100) / 10) .. "K" or tostring(fuelAmount)
          drawElement(23, 7, 1, 1, silver, nil, "(" .. sFuelAmount .. " / " .. sFuelLimit .. "K)     ")
          drawElement(14, 8, 1, 1, nil, nil, tostring(coal) .. " coal   ")
        end
        if gtSettings.password then drawElement(23, 11, 1, 1, silver, nil, tostring(unlockedClients.count) .. "  ") end
        drawElement(23, 10, 1, 1, gtRedstone and green or red, nil, tostring(gtRedstone) .. "  ")
        drawElement(23, termY - 1, 1, 1, gtSuccess and green or red, nil, tostring(gtSuccess) .. "  ")
      end
      reportStatus(netReceive())
    end
  end
end

local function firstRun()
  if not fs.exists("/data") then fs.makeDir("/data") end
  drawElement(2, 2, 1, 1, nil, nil, "Please name this turtle")
  drawElement(3, 3, 1, 1, nil, nil, "(8 characters or less)")
  repeat --# Set host name
    term.setCursorPos(2, 5)
    local newName = read():sub(1, 8)
    gtSettings.name = newName
  until newName ~= ""
  os.setComputerLabel(gtSettings.name) --# Set turtle label
  term.clear()
  drawElement(2, 2, 1, 1, nil, nil, "Please type in a short")
  drawElement(2, 3, 1, 1, nil, nil, "description (21 chars.)")
  repeat --# Set host description
    term.setCursorPos(2, 5)
    local newDesc = read():sub(1, 21)
    gtSettings.note = newDesc
  until newDesc ~= ""
  term.clear()
  drawElement(2, 2, 1, 1, nil, nil, "Select a color")
  local y = 3
  for k, v in pairs(colorBurst) do
    y = y + 1
    drawElement(2, y, 1, 1, nil, nil, k .. " = " .. v[1])
  end
  repeat --# Select color
    term.setCursorPos(2, 13)
    local newColor = string.upper(read():sub(1, 1))
    gtSettings.color = newColor
  until colorBurst[newColor]
  term.clear()
  drawElement(2, 2, 1, 1, nil, nil, "Would you like to password")
  drawElement(2, 3, 1, 1, nil, nil, "protect this turtle? [Y/N]")
  term.setCursorPos(2, 5)
  local lockQ = string.lower(read():sub(1, 1))
  if lockQ == "y" then
    local pass
    drawElement(2, 7, 1, 1, nil, nil, "Please enter a password...")
    repeat --# Set password
      term.setCursorPos(2, 9)
      pass = read()
    until pass ~= ""
    gtSettings.password = table.concat(pbkdf2(pass, "gt!Remote", 15))
    gtSettings.hashedPWs = true
  end
  saveData()
end

clearTerm()
if not turtle then error("This is not a turtle.", 0) end
drawElement(2, 1, 1, 1, nil, nil, "Configuring hardware . . .")
for _, side in pairs({ "left", "right" }) do
  if peripheral.isPresent(side) and peripheral.getType(side) == "modem" and peripheral.call(side, "isWireless") then
    netSide = side
    break
  end
end
if netSide == "none" then
  term.clear()
  drawElement(2, 2, 1, 1, red, black, "No wireless")
  drawElement(2, 3, 1, 1, nil, nil, "modem detected!")
  drawElement(2, 5, 1, 1, nil, nil, "gtHost REQUIRES")
  drawElement(2, 6, 1, 1, nil, nil, "a wireless modem.")
  term.setTextColor(colors.white)
  term.setCursorPos(1, 9)
  return
end
if not fs.exists(config) then
  firstRun()
  term.clear()
  drawElement(2, 3, 1, 1, nil, nil, "Configuration complete . . .")
else
  drawElement(2, 3, 1, 1, nil, nil, "Ingesting configuration data . . .")
  local gtHConfig = fs.open(config, "r") or error("init: Cannot open " .. config .. " for reading", 0)
  gtSettings = textutils.unserialize(gtHConfig.readAll())
  gtHConfig.close()
  if not gtSettings.newColors then
    local oldColors = {
      L = "S";
      Y = "I";
    }
    if oldColors[gtSettings.color] then gtSettings.color = oldColors[gtSettings.color] end
    gtSettings.newColors = true
    saveData()
  end
  if gtSettings.password and not gtSettings.hashedPWs then
    gtSettings.password = table.concat(pbkdf2(gtSettings.password, "gt!Remote", 15))
    gtSettings.hashedPWs = true
    saveData()
  end
end
if gtSettings.password then lockState = true end
drawElement(2, 5, 1, 1, nil, nil, "Getting fuel level . . .")
turtleFuelLimit = turtle.getFuelLimit()
getFuelLevel()
drawElement(2, 7, 1, 1, nil, nil, "Scanning inventory . . .")
inventorySlots()
selectedSlot = turtle.getSelectedSlot()
drawElement(2, 9, 1, 1, nil, nil, "Examining redstone . . .")
gtRedstone = rs.getOutput("front")
drawElement(2, 11, 1, 1, nil, nil, "Acquiring GPS fix . . .")
if not rednet.isOpen(netSide) then rednet.open(netSide) end
loc.x, loc.y, loc.z = gps.locate(2)
if not loc.x then
  loc.x, loc.y, loc.z = "No GPS Fix", "No GPS Fix", "No GPS Fix"
end
drawElement(2, 13, 1, 1, nil, nil, "Hosting services . . .")
rednet.host("gtRemote", gtSettings.name .. thisCC)
gtSuccess = true
if tArgs[1] then
    parallel.waitForAny(foregroundShell, gtHostKernel)
else
  redraw = true
  parallel.waitForAny(gtHostKernel, charInput)
end