Question

The inet_pton function returns an IP address in its packed in_addr representation, i.e. ::1 becomes “. How can I convert this 16-byte value to an integer? (Well, the string representation of an integer.)

Answer 1

The following code does it:

$in_addr = inet_pton('21DA:00D3:0000:2F3B:02AA:00FF:FE28:9C5A');
$unpacked = unpack('a16', $in_addr);
$unpacked = str_split($unpacked[1]);
$binary = '';
foreach ($unpacked as $char) {
    $binary .= str_pad(decbin(ord($char)), 8, '0', STR_PAD_LEFT);
}

$gmp = gmp_init($binary, 2);
$str = gmp_strval($gmp);

You can also reverse it with the following code:

$gmp = gmp_init($str);
$binary = gmp_strval($gmp, 2);
$binary = str_pad($binary, 128, '0', STR_PAD_LEFT);

$binary_arr = str_split($binary, 8);
$packed = '';
foreach ($binary_arr as $char) {
    $packed .= chr(bindec($char));
}

$packed = pack('a16', $packed);
echo inet_ntop($packed);