gohome

local drone = component.proxy(component.list('drone')())
local port = 43
local modem = component.proxy(component.list('modem')())
modem.open(port)

local distance = 0
local d1 = 0

local function ping()
  while true do
    e, _, _, _, d, msg=computer.pullSignal(1)
    if e=='modem_message' and msg == 'PING' then
      distance = d
      return true
    end
  end
end

local function mv(dir)
  d1 = distance
  if dir == 1 then
    drone.move(1, 0, 0)
    ping()
    if d1 > distance then
      drone.move(1, 0, 0)
    else
      drone.move(-2, 0, 0)
    end
  elseif dir == 2 then
    drone.move(0, 1, 0)
    ping()
    if d1 > distance then
      drone.move(0, 1, 0)
    else
      drone.move(0, -2, 0)
    end
  elseif dir == 3 then
    drone.move(0, 0, 1)
    ping()
    if d1 > distance then
      drone.move(0, 0, 1)
    else
      drone.move(0, 0, -2)
    end
  end
end

ping()

while distance > 3 do
  for i = 1, 3 do
    mv(i)
  end
end