https function

[admin]

Do not set the source if payload is not provided:

Code:

local source

if payload then
  source = ltn12.source.string(payload)
end

...

local res, err, res_headers, status = htps.request({
  ...
  source = source, -- source will be nil if payload is not provided
  ...
})

There's another issue with your code when payload or add_headers are set: ip/port variables are not set, so the function call will produce an error. You can use socket.url to parse the url into parts: http://w3.impa.br/~diego/software/luasoc...html#parse