README.md

# locus

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### <span id="locus_-_Geolocation_and_ASN_lookup_of_IP_addresses_using_MaxMind_GeoIP2">locus - Geolocation and ASN lookup of IP addresses using MaxMind GeoIP2</span>

`locus` is library for Erlang/OTP and Elixir that allows you to pinpoint
the country, city or ASN of IPv4 and IPv6 addresses.

The free [MaxMind
databases](https://dev.maxmind.com/geoip/geoip2/geolite2/) you choose
are downloaded on-demand, cached on the filesystem and updated
automatically.

You're encouraged to host your own private copies of the databases when
using this library in production, both for reliability and netiquette
towards MaxMind.

#### <span id="Usage">Usage</span>

Clone the repository and run `make console` to bring up a
shell.

##### <span id="1._Start_the_database_loader">1. Start the database loader</span>

``` erlang
URL = "https://geolite.maxmind.com/download/geoip/database/GeoLite2-Country.tar.gz",
ok = locus:start_loader(country, URL).
```

##### <span id="2._Wait_for_the_database_to_load_(optional)">2. Wait for the database to load (optional)</span>

``` erlang
% Either block indefinitely
{ok, _DatabaseVersion} = locus:wait_for_loader(country).
```

``` erlang
% ... or give-up after 30 seconds
{ok, _DatabaseVersion} = locus:wait_for_loader(country, 30000). % {error,timeout}
```

##### <span id="3._Lookup_IP_addresses">3. Lookup IP addresses</span>

``` erlang

% > locus:lookup(country, "93.184.216.34").
% > locus:lookup(country, "2606:2800:220:1:248:1893:25c8:1946").

{ok,#{<<"continent">> =>
          #{<<"code">> => <<"NA">>,
            <<"geoname_id">> => 6255149,
            <<"names">> =>
                #{<<"de">> => <<"Nordamerika">>,
                  <<"en">> => <<"North America">>,
                  <<"es">> => <<"Norteamérica"/utf8>>,
                  <<"fr">> => <<"Amérique du Nord"/utf8>>,
                  <<"ja">> => <<"北アメリカ"/utf8>>,
                  <<"pt-BR">> => <<"América do Norte"/utf8>>,
                  <<"ru">> => <<"Северная Америка"/utf8>>,
                  <<"zh-CN">> => <<"北美洲"/utf8>>}},
      <<"country">> =>
          #{<<"geoname_id">> => 6252001,
            <<"iso_code">> => <<"US">>,
            <<"names">> =>
                #{<<"de">> => <<"USA">>,
                  <<"en">> => <<"United States">>,
                  <<"es">> => <<"Estados Unidos">>,
                  <<"fr">> => <<"États-Unis"/utf8>>,
                  <<"ja">> => <<"アメリカ合衆国"/utf8>>,
                  <<"pt-BR">> => <<"Estados Unidos">>,
                  <<"ru">> => <<"США"/utf8>>,
                  <<"zh-CN">> => <<"美国"/utf8>>}},
      <<"registered_country">> =>
          #{<<"geoname_id">> => 6252001,
            <<"iso_code">> => <<"US">>,
            <<"names">> =>
                #{<<"de">> => <<"USA">>,
                  <<"en">> => <<"United States">>,
                  <<"es">> => <<"Estados Unidos">>,
                  <<"fr">> => <<"États-Unis"/utf8>>,
                  <<"ja">> => <<"アメリカ合衆国"/utf8>>,
                  <<"pt-BR">> => <<"Estados Unidos">>,
                  <<"ru">> => <<"США"/utf8>>,
                  <<"zh-CN">> => <<"美国"/utf8>>}}}}
```

#### <span id="Details">Details</span>

##### <span id="Requirements">Requirements</span>

  - Erlang/OTP 18.0 or higher
  - rebar3

##### <span id="Documentation">Documentation</span>

Documentation is hosted on [HexDocs](https://hexdocs.pm/locus/).

##### <span id="Databases">Databases</span>

  - The free GeoLite2 [Country, City and ASN
    databases](https://dev.maxmind.com/geoip/geoip2/geolite2/) were all
    successfully tested; presumably `locus` can deal with any MaxMind DB
    -formatted database that maps IP address prefixes to arbitrary data,
    but no [commercial
    databases](https://dev.maxmind.com/geoip/geoip2/downloadable/) have
    yet been tested
  - The databases are loaded into memory (mostly) as-is; reference
    counted binaries are shared with the application callers using ETS
    tables, and the original binary search tree is used to lookup
    addresses. The data for each entry is decoded on the fly upon
    successful lookups.

##### <span id="Formats">Formats</span>

  - Only gzip-compressed tarballs are supported at this moment
  - The first file to be found, within the tarball, with an .mmdb
    extension, is the one that's chosen for loading
  - The implementation of [MaxMind DB
    format](https://maxmind.github.io/MaxMind-DB/) is mostly complete

##### <span id="Downloads_and_updates">Downloads and updates</span>

  - The downloaded tarballs are uncompressed in memory
  - The 'last-modified' response header, if present, is used to
    condition subsequent download attempts (using 'if-modified-since'
    request headers) in order to save bandwidth
  - The downloaded tarballs are cached on the filesystem in order to
    more quickly achieve readiness on future launches of the database
    loader
  - Until the database loader achieves readiness, download attempts are
    made every minute; once readiness is achieved (either from cache or
    network), this interval increases to every 6 hours

##### <span id="Caching">Caching</span>

  - Caching is a best-effort; the system falls back to relying
    exclusively on the network if needed
  - A caching directory named 'locus\_erlang' is created under the
    ['user\_cache'
    basedir](http://erlang.org/doc/man/filename.html#basedir-3)
  - Cached tarballs are named after the SHA256 hash of their source URL
  - Modification time of the tarballs is extracted from 'last-modified'
    response header (when present) and used to condition downloads on
    subsequent boots and save bandwidth
  - Caching can be disabled by specifying the `no_cache` option when
    running `:start_loader`

##### <span id="Logging">Logging</span>

  - Five logging levels are supported: `debug`, `info`, `warning`,
    `error` and `none`
  - The backend is
    [error\_logger](http://erlang.org/doc/man/error_logger.html); this
    usually plays nicely with `lager`
  - The default log level is `error`; it can be changed in the
    application's `env` config
  - To tweak the log level in runtime, use `locus_logger:set_loglevel/1`

##### <span id="Event_subscription">Event subscription</span>

  - Any number of event subscribers can be attached to a database loader
    by specifying the `{event_subscriber, Subscriber}` option when
    starting the database
  - A `Subscriber` can be either a module implementing the
    `locus_event_subscriber` behaviour or an arbitrary `pid()`
  - The format and content of reported events can be consulted in detail
    on the `locus_event_subscriber` module documentation; most key steps
    in the loader pipeline are reported (download started, download
    succeeded, download failed, caching succeeded, loading failed, etc.)

#### <span id="Alternatives_(Erlang)">Alternatives (Erlang)</span>

  - [egeoip](https://github.com/mochi/egeoip): IP Geolocation module,
    currently supporting the MaxMind GeoLite City Database
  - [geodata2](https://github.com/brigadier/geodata2): Application for
    working with MaxMind geoip2 (.mmdb) databases
  - [geoip](https://github.com/manifest/geoip): Returns the location of
    an IP address; based on the ipinfodb.com web service
  - [geolite2data](https://hex.pm/packages/geolite2data): Periodically
    fetches the free MaxMind GeoLite2
    databases
  - [ip2location-erlang](https://github.com/ip2location/ip2location-erlang):
    Uses IP2Location geolocation database

#### <span id="Alternatives_(Elixir)">Alternatives (Elixir)</span>

  - [asn](https://hex.pm/packages/asn): IP-to-AS-to-ASname lookup
  - [freegeoip](https://hex.pm/packages/freegeoip): Simple wrapper for
    freegeoip.net HTTP API
  - [freegeoipx](https://hex.pm/packages/freegeoipx): API Client for
    freegeoip.net
  - [geoip](https://hex.pm/packages/geoip): Lookup the geo location for
    a given IP address, hostname or Plug.Conn instance
  - [geolix](https://hex.pm/packages/geolix): MaxMind GeoIP2 database
    reader/decoder
  - [plug\_geoip2](https://hex.pm/packages/plug_geoip2): Adds geo
    location to a Plug connection based upon the client IP address by
    using MaxMind's GeoIP2 database
  - [tz\_world](https://hex.pm/packages/tz_world): Resolve timezones
    from a location efficiently using PostGIS and Ecto

#### <span id="License">License</span>

MIT License

Copyright (c) 2017-2018 Guilherme Andrade

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

`locus` is an independent project and has not been authorized,
sponsored, or otherwise approved by MaxMind.

`locus` includes code extracted from OTP source code, by Ericsson AB,
released under the Apache License
2.0.

-----

*Generated by EDoc, Feb 11 2018, 20:15:04.*