Rough cut coroutine based provisioning system

loadHTTPimage.lua

local post, yield = node.task.post, coroutine.yield
local max_namelen = 31
local request = '\z
  %s %s%s.img HTTP/1.1\r\n\z
  User-Agent: ESP8266 app (linux-gnu)\r\n\z
  Accept: application/octet-stream\r\n\z
  Accept-Encoding: identity\r\n\z
  Host: %s\r\n\z
  Connection: %s\r\n\r\n'
local host, dir, image, onDone
local cleanup, receiver

local function protected_receiver (soc, rec) -- Upval:post, next_rec, image
  local status   = tonumber(rec:match('HTTP/1.1%s+(%d+)') or '0')
  assert(status == 200, "Image %s does not exist" % image)
  local etag     = rec:lower():match('\netag: *"([%d%-a-f]*)"\r')
  local tailsize = max_namelen - #image - #'.img.'
  local filename = image .. '.img.' .. (etag or ''):sub(-tailsize)
  if etag and file.exists(filename) then
    return "Image %s already downloaded" % image
  end
  soc:send(request % {'GET', dir, image, host,'Close'})
  soc, rec = yield()
  local i      = rec:find('\r\n\r\n',1,true) or 1
  local hdr    = rec:sub(1,i+1):lower()
        rec    = rec:sub(i+4)
  local size   = tonumber(hdr:match('\ncontent%-length: *(%d+)\r')) or
                   error 'invalid size returned'
  assert(etag == hdr:match('\netag: *"([%d%-a-f]*)"\r'), "Etag missmatch")
  local f = file.open(filename, 'w+')
  local j, nr = 0, 0
  repeat
    f:write(rec)
    j, nr = j + #rec, nr + 1
    if nr % 4 == 1 then -- hold and unhold socket to prevent overrun
      soc:hold()
      post(0, function() soc:unhold() end)
    end
    collectgarbage()
    if j < size then soc, rec = yield() end
  until j >= size
  f:close()
  if j ~= size then file.erase(filename) end
  assert(j==size, "File size mismatch %s removed" % filename)

  soc:on('receive', nil)
  for n,l in pairs(file.list('^%s.img' % image)) do
    if n ~= filename then file.remove(n) end
  end
  return "Image %s created as %s (%d bytes)" % {image, filename, size}
end

receiver = coroutine.wrap(
  function(soc, rec) -- Upval: protected_receiver, post
    local status, message = pcall(protected_receiver, soc, rec)
    post(function() cleanup(status, message, soc) end)
  end)

local function doRequest(sk,hostIP)
  if not hostIP then return end
  local con = net.createConnection(net.TCP,0)
  con:connect(80,hostIP)
  con:on("connection", function(sck) -- Upval: dir, iage, host
    sck:send(request % {'HEAD', dir, image, host,'Keep-Alive'})
    sck:on("receive", receiver)
  end)
end

local cleanTBD = true
cleanup = function (status, message, soc)  -- Upval: onDone, post
  if not cleanTBD then return end
  cleanTBD = false
  if soc and soc.close  then soc:__gc() end
  receiver=nil
  collectgarbage()
  if onDone and type(onDone)=="function" then
    post(function() onDone(status, message) end) -- Upval onDone, status, message
  else
    print ("%s: %s" % {status and "Success" or "Failed", message})
  end
end

return function(h, d, i, f)
  host, dir, image, onDone = h, d, i, f
  net.dns.resolve(host, doRequest)
end

syncHTTPimages.lua

local ssid, pwd = 'passiveHouse','IN.TE.SPERANT.DOMINE'
local host, dir = '192.168.1.2','/test2/'
local images = 'api attrib big bitwise closure code constructs \z
                coroutine db errors esp-files events files gc goto \z
                literals locals main math nextvar pm sort stackbreak \z
                strings tpack utf8 vararg verybig '
local check
local post,yield = node.task.post, coroutine.yield
local httpload = dofile'HTTPloadfile.lua'

check = coroutine.wrap(function(t)
  if wifi.sta.status() ~= wifi.STA_GOTIP and not wifi.sta.getip() then
    wifi.setmode(wifi.STATION, false)
    wifi.sta.config { ssid = ssid, pwd  = pwd, save = false }
    while wifi.sta.status() == wifi.STA_GOTIP do
      uart.write(0,".") 
      yield()
    end
  end
  print("NodeMCU connected", node.heap(), wifi.sta.getip())
  t:unregister()
  for i in images:gmatch("([%w%-]+) ") do
    print ("Starting download for %s" % i)
    post(function() httpload(host, dir, i, check) end)
    local status, message = yield()       
    if status then
      print(message)
    else
      print("Load failed:", message)
    end
  end
end)

tmr.create():alarm(500, tmr.ALARM_AUTO,coroutine.wrap(check))