http_response_send.lua

------------------------------------------------------------------------------
-- send
------------------------------------------------------------------------------
return function(res, data, status)
 local conn = res.conn
 local buf
 --   write protocol headers
 buf = "HTTP/1.1 " .. tostring(status or res.statuscode) .. " " .. dofile('http-' .. tostring(status or res.statuscode)) .. "\r\n"
 --   write response headers
 res:addheader("Server", "NodeMCU")
 if data then
  res:addheader("Content-Length", string.len(data))
 end
 for key, value in pairs(res.headers) do
  -- send header
  buf = buf .. key .. ": " .. value .. "\r\n"
 end
 buf = buf .. "\r\n"
 --   write body if relevant
 if data then
  buf = buf .. data
  buf = buf .. "\r\n"
 end
 -- send
 conn:send(buf)
 buf = nil
 -- Remove default sent callback
 conn:on("sent", nil)
 -- Send last chunk and close connection
 conn:on("sent", function(conn)
   -- Close connection
   conn:on('sent', nil)
   -- Call termination callback
   res:close()
 end
 )
 conn:send("0\r\n\r\n")
end