Validator checking IPv4 mapped IPv6 addresses

[CMCDragonkai]

I'm trying to use the validator to know whether an IP address is IPv4 or IPv6.

  const [isIPv4] = Validator.isValidIPv4String(host);
  const [isIPv6] = Validator.isValidIPv6String(host);
  if (isIPv4) {
    return [host as Host, 'udp4'];
  } else if (isIPv6) {
    return [host as Host, 'udp6'];
  } else {
    // THIS IS A HOSTNAME not an IP address!
  }

Well the issue is that if I pass it an "IPv4 mapped IPv6 address" like ::ffff:127.0.0.1, it ends up in the else block.

This means in my code, it thinks its a hostname, and not a host.

I think the validator should accept that IPv4 mapped IPv6 addresses are ipv6 addresses. Because they are legitimate ipv6 address that can be used later.

[dadepo]

Thanks for reporting this. A bit busy at the moment but I'll try and look into this over the weekend

[CMCDragonkai]

Cool! If you do fix it, please release as soon as you can as I'm trying to implement a QUIC library that relies on this.

[CMCDragonkai]

I noticed that new IPv6('::ffff:127.0.0.1'); also fails with Given string is already longer than given final length after padding: 4.

[CMCDragonkai]

So I have found out that this library prefers this format:

::ffff:7f00:1

Even though this is the equivalent:

::ffff:127.0.0.1

So nodejs dgram socket actually accepts both formats and both work.

I had a work around like this:

function isIPv4MappedIPv6(host: string) {
  if (host.startsWith('::ffff:')) {
    const ipv4 = host.slice('::ffff:'.length);
    // so it turns out ::ffff:7f00:1 is also the same as ::ffff:127.0.0.1
    // return true;
    if (isIPv4(ipv4)) {
      return true;
    }
  }
  return false;
}

But that ended up failing on ::ffff:7f00:1. So I actually need to parse the hex digits too...