Module: Iriq::RegistrableDomain

Defined in:
lib/iriq/registrable_domain.rb

Overview

Heuristic registrable-domain extractor. Strips subdomains so that api.foo.com and app.foo.com both resolve to foo.com.

Uses an inline allowlist of the ~50 most common multi-label public suffixes (.co.uk, .com.au, .gov.uk, etc.) — covers the long tail of real-world traffic without the ~3 MB cost of bundling the full Public Suffix List. Niche multi-label TLDs (.priv.no, .tas.gov.au, etc.) will be over-stripped; install the ‘public_suffix` gem and wire it in if accuracy on those matters for your workload.

Constant Summary collapse

TWO_LABEL_SUFFIXES =

rubocop:disable Layout/LineLength

%w[
  co.uk org.uk gov.uk ac.uk net.uk me.uk ltd.uk plc.uk sch.uk
  co.jp ac.jp or.jp ne.jp go.jp gr.jp ed.jp lg.jp
  com.au net.au org.au edu.au gov.au asn.au id.au
  co.nz net.nz org.nz govt.nz ac.nz school.nz
  com.br net.br org.br gov.br edu.br
  com.cn net.cn org.cn gov.cn edu.cn ac.cn
  co.za net.za org.za gov.za ac.za
  co.kr ne.kr or.kr re.kr go.kr ac.kr
  co.in net.in org.in gov.in ac.in
  co.il net.il org.il gov.il ac.il muni.il
  com.mx net.mx org.mx gob.mx edu.mx
  com.ar net.ar org.ar gov.ar
  com.hk net.hk org.hk gov.hk edu.hk
  com.tw net.tw org.tw gov.tw edu.tw
  com.sg net.sg org.sg gov.sg edu.sg per.sg
  com.tr net.tr org.tr gov.tr edu.tr k12.tr
].to_set.freeze
IP_V4_RE =

rubocop:enable Layout/LineLength

/\A\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\z/.freeze

Class Method Summary collapse

Class Method Details

.for(host) ⇒ Object

Given an authority (hostname, no port), return the registrable domain. Returns the input unchanged for IP literals, single-label hosts (‘localhost`), and hosts that already match a 2-label apex.



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# File 'lib/iriq/registrable_domain.rb', line 40

def for(host)
  return host if host.nil? || host.empty?
  return host if IP_V4_RE.match?(host)

  labels = host.split(".")
  return host if labels.size <= 2

  tail_two = labels.last(2).join(".")
  if TWO_LABEL_SUFFIXES.include?(tail_two)
    # Multi-label public suffix — keep last 3 labels (`foo.co.uk`).
    labels.last(3).join(".")
  else
    labels.last(2).join(".")
  end
end