Hvor

Hvor ("where", in Danish) is a mountable Rails engine that imports IP2Location LITE CSV data (IPv4 and IPv6 ranges mapped to country_code) into an Hvor::IPRange table, and answers "what country is this IP in?" via a cached lookup and a small JSON API.

Add to your Gemfile:

gem "hvor"

Then:

bundle
bin/rails generate hvor:install
bin/rails hvor:install:migrations
bin/rails db:migrate

The install generator writes config/initializers/hvor.rb. At minimum, set an IP2Location LITE token there (or via the IP2LOCATION_TOKEN env var) — get one free at https://lite.ip2location.com/.

Enqueue Hvor::ImportIpRangesJob (on a daily/weekly schedule via whatever job scheduler your app uses — IP2Location LITE data updates roughly monthly). It downloads the IPv4 and IPv6 country CSV zips, and does an atomic dump-and-repopulate of Hvor::IPRange — the table is only ever replaced once both files have downloaded and parsed successfully.

Hvor::ImportIpRangesJob.perform_later

Hvor.lookup("1.0.0.1")        # => "AU"
Hvor.lookup("::ffff:8.8.8.8") # => "US" (ipv4-mapped ipv6 is unwrapped to plain ipv4)

Results (including misses) are cached via Rails.cache for Hvor.configuration.cache_expires_in (default 24 hours). A country_code of "-" means the IP falls in an unallocated/private/reserved range (this is IP2Location's own placeholder — e.g. Hvor.lookup("127.0.0.1") will typically return "-", not nil; nil means the IP simply isn't covered by any imported range, which shouldn't happen once the table is populated).

Mount the engine in your host app's routes:

mount Hvor::Engine => "/hvor"

This exposes:

• GET /hvor/lookup?ip=1.2.3.4 — {"ip":"1.2.3.4","country_code":"AU"}
• GET /hvor/lookup/me — same, but for the requesting client's own IP (request.remote_ip)

An invalid ip param returns 400 with {"error": "..."}.

# config/initializers/hvor.rb
Hvor.configure do |config|
  config.api_token = ENV["IP2LOCATION_TOKEN"]
  config.ipv4_product_code = "DB1LITECSV"      # country-only LITE database
  config.ipv6_product_code = "DB1LITECSVIPV6"
  config.cache_store = -> { Rails.cache }
  config.cache_expires_in = 24.hours
  config.import_batch_size = 5_000
  config.download_timeout = 60
  config.queue_name = :hvor
end

hvor_ip_ranges stores IPv4 bounds as bigint and IPv6 bounds as a zero-padded 32-character lowercase hex string (IPv6's 128-bit range doesn't fit in a bigint), so lookups work identically on PostgreSQL, MySQL, and SQLite. The migration pins a binary-order collation on the IPv6 columns (C on Postgres, ascii_bin on MySQL) so string comparison matches numeric ordering regardless of the database's default locale — if you're running CI against a database other than SQLite, make sure that migration path gets exercised at least once, since SQLite's default collation is already binary and won't catch a regression here.

MIT.