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WhenWhere Server

The repository provides an API and implementation for the Nerves Project's Internet connectivity check server, whenwhere.nerves-project.org. The server provides a highly available endpoint that is inexpensive to maintain. Of course, this is an open source project and no uptime guarantees are being made. Luckily, the source is available here so that you can set one up yourself.

Why does this project exist? We were defeated by captive portals tricking devices that they had Internet when they didn't.

The reference implementation uses AWS CloudFront Functions. It's certainly possible to replicate the API elsewhere. Please send a PR or repository pointer if you'd like to share another way.

Features include:

  • Multiple ways to avoid being tricked by overly aggressive HTTP caches
  • Millisecond timestamp for setting clocks
  • JSON and Erlang Term Format responses
  • Optional device geo-location
  • Optional public IP address and port used to make the request

Examples

If you're not using Elixir, run this:

$ curl https://whenwhere.nerves-project.org | jq .
{
  "now": "2024-06-20T02:19:59.878Z",
  "time_zone": "Australia/Brisbane",
  "latitude": "-27.46790",
  "longitude": "153.03250",
  "country": "AU",
  "country_region": "QLD",
  "city": "Brisbane",
  "address": "103.216.220.102:11591"
}

In Elixir, here's an example using Req:

Mix.install([
  {:req, "~> 0.5.0"}
])

Req.get!("http://whenwhere.nerves-project.org/").body
#=> %{
#     "now" => "2024-05-29T00:43:08.383Z",
#     "time_zone" => "Australia/Brisbane",
#     "latitude" => "-27.46790",
#     "longitude" => "153.03250",
#     "country" => "AU",
#     "city" => "Brisbane",
#     "address" => "144.48.39.229:1403"
#   }

Here's a minimal :httpc example that requests an Erlang binary term instead:

Application.ensure_all_started(:inets)

{:ok, {_, _, body}} = :httpc.request(:get, {"http://whenwhere.nerves-project.org/", [{~c"content-type", "application/x-erlang-binary"}]}, [], [])
body |> IO.iodata_to_binary() |> :erlang.binary_to_term([:safe])
#=> %{
#     "now" => "2024-05-29T00:43:08.383Z",
#     "time_zone" => "Australia/Brisbane",
#     "latitude" => "-27.46790",
#     "longitude" => "153.03250",
#     "country" => "AU",
#     "city" => "Brisbane",
#     "address" => "144.48.39.229:1403"
#   }

API

There's only one endpoint and the path to it isn't specified.

Only HTTP GET and HEAD methods are supported. Clients should make HEAD requests when they don't need any information in the body of the response.

One query parameter is supported:

  • nonce - an up to 32 alphanumeric string. Non-alphanumeric or longer strings result in an error response.

Both HTTP GET and HEAD methods return the following headers:

  • x-now - ISO 8601 date/time string with millisecond precision in UTC (e.g., 2024-05-29T00:22:09.890Z)
  • x-nonce - The value of the nonce query parameter if specified

The content-type request header selects JSON-encoded (applictaion/json) or Erlang Term Format-encoded (application/x-erlang-binary) results. JSON is the default. The contents will be a map with the following fields. Note that many are optional.

  • "now" - ISO 8601 data/time string with millisecond precision in UTC
  • "time_zone" - Optional geo-located time zone in IANA time zone database format
  • "latitude" - Optional approximate latitude
  • "longitude" - Optional approximate longitude
  • "country" - Optional ISO 3166-1 alpha-2 country code
  • "country_region" - Optional ISO 3166-1 alpha-2 country code
  • "city" - Optional name of the nearest city
  • "address" - Optional IP address and port that made the request

CloudFront Function setup

Consult the AWS CloudFront Function setup and use the provided index.js.

For geo-location support, attach the AllViewerAndCloudFrontHeaders-2022-06 origin request policy.

Tests

This project comes with simple tests to verify that the server is responding correctly. Make sure Elixir is installed and then run:

./validate.exs

Modify the script if your installation differs.