OpenComputers - NET API (DNS Server)

--[[
    Wireless-Modem-API (DNS SERVER)

    This server picks requests up and registering associates
    their wished address with their modem address (rejects if address
    is taken.) (NOTE: They aren't deleted until restart)

    Performance probably not great.

    It also constantly sends a broadcast to let clients know of it's
    modem-address. (I may change that in the future, so stay tuned! :) )

    INFORMATION:
    You need a computer and screen with color support AND you need my
    multitasking API, which should be located at /lib/oc_multitasking_api.lua

  By Piorjade

]]

conf = {
    _PORT = 8080,                 ----Clients must have the same
}

component = require("component")
computer = require("computer")
ser = require("serialization")
multitask = require("oc_multitasking_api")
os = require("os")
term = require("term")
event = require("event")
net = {}
card = nil
c = 0
gpu = term.gpu()
function log(str)
  local tCol = gpu.getForeground()
  gpu.setForeground(0x66ff66)
  term.write("[LOG] ")
  gpu.setForeground(tCol)
  print(str)
end
function err(str)
  local tCol = gpu.getForeground()
  gpu.setForeground(0xff3300)
  term.write("[ERROR] ")
  gpu.setForeground(tCol)
  print(str)
end

for addr, b in component.list("modem") do
  card = component.proxy(addr)
  break
end
if not card then return false, "no modem found" end
card.open(conf._PORT)
if card.isOpen(conf._PORT) then
  log("Opened on port: "..tostring(conf._PORT))
else
  err("FAILED TO OPEN PORT: "..tostring(conf._PORT))
end

print("DNS server is running, press enter to quit properly.")

meta = {
  type = "dns_server",
  host = "Piorjade",
}

list = {        ----List of all currently registered URLs
  --[[ EXAMPLE
  0abc-blah-blah-blah = "ww2.google.co.uk"
  ]]
}

cmds = {             ----Short commands
  rURL = function(url, addr)
    for each, addr in pairs(list) do
      if addr == url then
        return false
      end
    end
    list[addr] = url
    return true
  end,
  dURL = function(url, addr)
    if list[addr] == url then
      list[addr] = nil
      return true
    else
      return false
    end
  end,
  gADDR = function(url)
    for each, addr in pairs(list) do
      if addr == url then
        return each
      end
    end
  end,
  gURL = function(addr)
    return list[addr]
  end,
  gAll = function()
    return list
  end
}

local astr = [[
  while true do
    card.broadcast(conf._PORT, "DNS_SERVER", ser.serialize(meta))
    for a, b in ipairs(list.errorLog) do
      err("internal_function: "..b)
    end
    sleep(2)
  end]]

local bstr = [[
  while true do
    local _, myAddr, sAddr, port, distance, command, arg1, arg2 = event.pull("modem_message")
    if port == conf._PORT then
      if command == "rURL" then
        local ok, msg = cmds[command](arg1, sAddr)
        log(tostring(sAddr).." requested register for "..arg1..".")
        if not ok then
          err("Registration of "..arg1.." failed.")
          card.send(sAddr, conf._PORT, "DNS_REGISTER_FAILED")
        else
          log("Registration of "..arg1.." succeeded.")
          card.send(sAddr, conf._PORT, "DNS_REGISTER_SUCCESS")
        end
      elseif command == "dURL" then
        local ok, msg = cmds[command](arg1, sAddr)
        log(tostring(sAddr).." requested delete for "..arg1..".")
        if not ok then
          err("Deletion of "..arg1.." failed.")
          card.send(sAddr, conf._PORT, "DNS_DELETE_FAILED")
        else
          log("Deletion of "..arg1.." succeeded.")
          card.send(sAddr, conf._PORT, "DNS_DELETE_SUCCESS")
        end
      elseif command == "gADDR" then
        local ok, msg = cmds[command](arg1)
        log(tostring(sAddr).." requested address of "..arg1)
        if not ok then
          err("Address of "..arg1.." not found.")
          card.send(sAddr, conf._PORT, "DNS_URL_NOT_FOUND")
        else
          log("Address of "..arg1.." found.")
          card.send(sAddr, conf._PORT, ok)
        end
      elseif command == "gURL" then
        local ok, msg = cmds[command](arg1)
        log(tostring(sAddr).." requested URL of "..arg1)
        if not ok then
          err("URL of "..arg1.." not found.")
          card.send(sAddr, conf._PORT, "DNS_ADDR_NOT_FOUND")
        else
          log("URL of "..arg1.." found.")
          card.send(sAddr, conf._PORT, ok)
        end
      elseif command == "gAll" then
        local list = cmds[command]()
        list = ser.serialize(list)
        log(tostring(sAddr).." requested list of all URLs")
        card.send(sAddr, conf._PORT, list)
      end
    end
  end]]
local env = {}
setmetatable(env, {__index = _ENV})

local cstr = [[
  local keyboard = require("keyboard")
  while true do
    local _, addr, char, code, pn = event.pull()
    if _ == "key_down" and keyboard.keys[code] == "enter" then
      log("QUIT BY USER")
      multitask.quit()
      break
    end
  end
]]

list = multitask.createTasklist()
multitask.createTask(list, "function a", astr, env)
multitask.createTask(list, "function b", bstr, env)
multitask.createTask(list, "function c", cstr, env)
multitask.runAll(list)
card.close(conf._PORT)