server/helpers/dns.ts


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import { lookup } from 'dns'
import { parse as parseIP } from 'ipaddr.js'

function dnsLookupAll (hostname: string) {
  return new Promise<string[]>((res, rej) => {
    lookup(hostname, { family: 0, all: true }, (err, adresses) => {
      if (err) return rej(err)

      return res(adresses.map(a => a.address))
    })
  })
}

async function isResolvingToUnicastOnly (hostname: string) {
  const addresses = await dnsLookupAll(hostname)

  for (const address of addresses) {
    const parsed = parseIP(address)

    if (parsed.range() !== 'unicast') return false
  }

  return true
}

export {
  dnsLookupAll,
  isResolvingToUnicastOnly
}