isIP.js

import assertString from './util/assertString';
/**
11.3.  Examples

   The following addresses

             fe80::1234 (on the 1st link of the node)
             ff02::5678 (on the 5th link of the node)
             ff08::9abc (on the 10th organization of the node)

   would be represented as follows:

             fe80::1234%1
             ff02::5678%5
             ff08::9abc%10

   (Here we assume a natural translation from a zone index to the
   <zone_id> part, where the Nth zone of any scope is translated into
   "N".)

   If we use interface names as <zone_id>, those addresses could also be
   represented as follows:

            fe80::1234%ne0
            ff02::5678%pvc1.3
            ff08::9abc%interface10

   where the interface "ne0" belongs to the 1st link, "pvc1.3" belongs
   to the 5th link, and "interface10" belongs to the 10th organization.
 * * */
const IPv4SegmentFormat = '(?:[0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])';
const IPv4AddressFormat = `(${IPv4SegmentFormat}[.]){3}${IPv4SegmentFormat}`;
const IPv4AddressRegExp = new RegExp(`^${IPv4AddressFormat}$`);

const IPv6SegmentFormat = '(?:[0-9a-fA-F]{1,4})';
const IPv6AddressRegExp = new RegExp('^('
  + `(?:${IPv6SegmentFormat}:){7}(?:${IPv6SegmentFormat}|:)|`
  + `(?:${IPv6SegmentFormat}:){6}(?:${IPv4AddressFormat}|:${IPv6SegmentFormat}|:)|`
  + `(?:${IPv6SegmentFormat}:){5}(?::${IPv4AddressFormat}|(:${IPv6SegmentFormat}){1,2}|:)|`
  + `(?:${IPv6SegmentFormat}:){4}(?:(:${IPv6SegmentFormat}){0,1}:${IPv4AddressFormat}|(:${IPv6SegmentFormat}){1,3}|:)|`
  + `(?:${IPv6SegmentFormat}:){3}(?:(:${IPv6SegmentFormat}){0,2}:${IPv4AddressFormat}|(:${IPv6SegmentFormat}){1,4}|:)|`
  + `(?:${IPv6SegmentFormat}:){2}(?:(:${IPv6SegmentFormat}){0,3}:${IPv4AddressFormat}|(:${IPv6SegmentFormat}){1,5}|:)|`
  + `(?:${IPv6SegmentFormat}:){1}(?:(:${IPv6SegmentFormat}){0,4}:${IPv4AddressFormat}|(:${IPv6SegmentFormat}){1,6}|:)|`
  + `(?::((?::${IPv6SegmentFormat}){0,5}:${IPv4AddressFormat}|(?::${IPv6SegmentFormat}){1,7}|:))`
  + ')(%[0-9a-zA-Z-.:]{1,})?$');

export default function isIP(str, version = '') {
  assertString(str);
  version = String(version);
  if (!version) {
    return isIP(str, 4) || isIP(str, 6);
  }
  if (version === '4') {
    return IPv4AddressRegExp.test(str);
  }
  if (version === '6') {
    return IPv6AddressRegExp.test(str);
  }
  return false;
}