Convert python pack to php pack

Question

Hi, I have this python script

b_string = pack('>hqh2sh13sh5sh3sBiiihiiiiii',
                21, 0,
                len(country), country,
                len(device), device,
                len('1.3.1'), "1.3.1",
                len('Web'), "Web",
                27, 0, 0,
                3, 0, cid, lac,
                0, 0, 0, 0)

and I want to convert it to php, this is what I came with so far

$body= pack('nln2c*n13c*n5c*n3c*Ciiiniiiiii',
                    21, 0,
                    strlen($this->_mccToCountry[$this->_mcc]), $this->_mccToCountry[$this->_mcc],
                    strlen($this->_device), $this->_device,
                    strlen('1.3.1'), "1.3.1",
                    strlen('Web'), "Web",
                    27, 0, 0,
                    3, 0, $this->_cellId, $this->_lac,
                    0, 0, 0, 0);

The variables are same as those in python script, but i got this error

PHP Warning: pack(): Type n: too few arguments in .../application/extensions/Zend-extensions/NMS/Bts.php:150

The help will be very appreciated.

Answer 1

Your parameter string is all screwed up. You indicate in places that you are going to pass 2, 5, 3 and 13 shorts, but only provide one each time. You indicate that you are going to provide a series of characters but then you provide a NUL terminated string. You indicate that you will be providing an unsigned char but don't provide one. Try this format string instead:

'nlna*na*na*na*i3ni6'

Another option is to use serialize and deserialize instead. Not sure if it matters to you that the data is packed into bytes or serialized into strings.