Convert IP2Location Decimals to IP

Question

IP ranges in the ip2location database are represented by first and last IPs as integers.

I don't know how the conversion from IPs to integers is done, but documentation indicates it is equivalent to this code in PHP:

function ip62long($ipv6) {
  return (string) gmp_import(inet_pton($ipv6));
}

If it's a IPv4 (not IPv6), the IP is prepended with '::ffff:'.

I'm trying to import ip2location database into postgres using the column type INET. I would want to convert these integers back to IPs, i.e. revert this routine.

So far I'm using this code:

func StringToIp(in string) net.IP {
    var bigint big.Int
    bigint.SetString(in, 10)
    return bigint.Bytes()
}

That works fine for:

IPv6 addresses, e.g. 55838750788714571402502155597250560000 -> 2a02:26f7:e5c4:c6c1::

and would work in theory for

IPv4 addresses (without the ::ffff: prefix), e.g. 16909060 -> 1.2.3.4

But it does not work for these case:

All IPv4 prefixed with ::ffff:, e.g. 281470681743360 should become 0.0.0.0 instead of ?ffff00000000.
Cases like 0, 281470681743359, 281474439839744, 281474976710656.

I'm looking for a solution to convert all these values back to IPv4 or IPv6 addresses respectively to store them in postgres and look up IPs later on.

You should edit the question and add a description of the format produced by `ip62long()`. I am not interested in hunting it down by following the links. — Laurenz Albe, Oct 18 '22 at 06:01
There is no documentation available for `ip62long()`. `gmp_import` and `inet_pton` are builtin functions of PHP. — some-user, Oct 18 '22 at 06:06
PHP is open source, isn't it? Make it easy for the people who are willing to help you. — Laurenz Albe, Oct 18 '22 at 06:08

score 0 · Answer 1 · answered Oct 18 '22 at 06:52

The cause of the problem seems to be that bigint.Bytes() returns less than 16 Bytes if the integer doesn't need it, while net.IP expects either 4 or 16 Bytes.

Prepending the []byte up with enough zeros results in proper net.IP:

func StringToIp(in string) net.IP {
    var bigint big.Int
    bigint.SetString(in, 10)
    ip := bigint.Bytes()

    for len(ip) < 16 {
        ip = append([]byte{0x00}, ip...)
    }

    return ip
}

Happy to see and accept other, more elegant, ... solutions.

Convert IP2Location Decimals to IP

1 Answers1