# locus
[](https://hex.pm/packages/locus)
[](https://travis-ci.org/g-andrade/locus)
`locus` is library for Erlang/OTP and Elixir that allows you to pinpoint
the country, city or ASN of IP addresses using MaxMind GeoIP2.
The free [MaxMind
databases](https://dev.maxmind.com/geoip/geoip2/geolite2/) you choose
are loaded on-demand and, if using HTTP, 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.
#### Usage
Clone the repository and run `make console` to bring up a
shell.
##### 1\. Start the database loader
``` erlang
URL = "https://geolite.maxmind.com/download/geoip/database/GeoLite2-Country.tar.gz",
ok = locus:start_loader(country, URL).
% URL can also be a local path, e.g. "/opt/MaxMind/GeoLite2-Country.tar.gz"
```
##### 2\. Wait for the database to load (optional)
``` erlang
% Give up after 30 seconds
{ok, _DatabaseVersion} = locus:wait_for_loader(country, 30000). % {error,timeout}
```
##### 3\. Lookup IP addresses
``` erlang
% > locus:lookup(country, "93.184.216.34").
% > locus:lookup(country, "2606:2800:220:1:248:1893:25c8:1946").
{ok,#{prefix => {{93,184,216,0},24},
<<"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>>}}}}
```
#### Documentation
1. [File Formats](#file-formats)
2. [Database Types and Loading](#database-types-and-loading)
3. [Database Validation](#database-validation)
4. [HTTP URLs: Downloading and
Updating](#http-urls-downloading-and-updating)
5. [HTTP URLs: Caching](#http-urls-caching)
6. [Filesystem URLs: Loading and
Updating](#filesystem-urls-loading-and-updating)
7. [Logging](#logging)
8. [Event Subscriptions](#event-subscriptions)
9. [API Reference](#api-reference)
10. [Tested Setup](#tested-setup)
11. [License](#license)
12. [Alternative Libraries (Erlang)](#alternative-libraries-erlang)
13. [Alternative Libraries (Elixir)](#alternative-libraries-elixir)
##### File Formats
- Only gzip-compressed tarballs are supported as of 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
##### Database Types and Loading
- 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
2.x 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.
##### Database Validation
Databases, local or remote, can have their compatibility validated
through the `locus:analyze/1` function after they've been loaded (see
[function reference](#api-reference).)
Alternatively, they can also be checked from the command line by use of
the `locus` CLI utility:
1. Run `make cli` to build the script, named `locus`, which will be
deployed to the current directory.
2. Run
analysis:
``` shell
./locus analyze https://geolite.maxmind.com/download/geoip/database/GeoLite2-ASN.tar.gz
# Loading database from "https://geolite.maxmind.com/download/geoip/database/GeoLite2-ASN.tar.gz"...
# Database version {{2019,1,22},{11,42,28}} successfully loaded
# Analyzing database for flaws...
# Database is wholesome.
```
The script will exit with code 1 in case of failure, and 0 otherwise.
Run `./locus analyze --help` for a description of supported options and
arguments.
##### HTTP URLs: Downloading and Updating
- 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 a HTTP 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. These can be
tweaked using the `pre_readiness_update_period` and
`post_readiness_update_period` loader settings (in milliseconds.)
- When downloading from a HTTPS URL, the remote certificate will be
authenticated against a [list of known Certificate
Authorities](https://github.com/certifi/erlang-certifi) and
connection negotiation will fail in case of an expired certificate,
mismatched hostname, self-signed certificate or unknown certificate
authority. These checks can be disabled by specifying the `insecure`
loader option.
##### HTTP URLs: Caching
- 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`
##### Filesystem URLs: Loading and Updating
- The loaded tarballs are uncompressed in memory
- Until a filesystem database loader achieves readiness, load attempts
are made every 5 seconds; once readiness is achieved, this interval
increases to every 30 seconds and load attempts are dismissed as
long as the tarball modification timestamp keeps unchanged
##### Logging
- 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`
##### Event Subscriptions
- 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.)
##### API Reference
The API reference can be found on [HexDocs](https://hexdocs.pm/locus/).
##### Tested setup
- Erlang/OTP 17.4 or newer
- rebar3
##### License
MIT License
Copyright (c) 2017-2019 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.
##### Alternative Libraries (Erlang)
- [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
##### Alternative Libraries (Elixir)
- [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
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