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Hcaptcha

Hex.pm

A simple Elixir package for implementing hCAPTCHA in Elixir applications.

The package is fork of the recaptcha package which uses the same flow as needed for hCaptcha. It would also be possible to integrate hCaptcha in this package but I was not able to wait for PRs to be merged so I just forked the repo.

Important Notice

The repo works for me but is not tested that all configuration options or callbacks given by hCaptcha are processed correctly. Feel free to open PRs to resolve dependencies on the recaptcha API.

Installation

  1. Add hcaptcha to your mix.exs dependencies
  defp deps do
    [
      {:hcaptcha, "~> 0.0.2"},
    ]
  end
  1. List :hcaptcha as an application dependency
  def application do
    [ extra_applications: [:hcaptcha] ]
  end
  1. Run mix do deps.get, compile

Config

By default the public and private keys are loaded via the HCAPTCHA_PUBLIC_KEY and HCAPTCHA_PRIVATE_KEY environment variables.

  config :hcaptcha,
    public_key: {:system, "HCAPTCHA_PUBLIC_KEY"},
    secret: {:system, "HCAPTCHA_PRIVATE_KEY"}

JSON Decoding

By default hCaptcha will use Jason to decode JSON responses, this can be changed as such:

  config :hcaptcha, :json_library, Poison

Usage

Render the Widget

Use raw (if you're using Phoenix.HTML) and Hcaptcha.Template.display/1 methods to render the captcha widget.

For hcaptcha with checkbox

<form name="someform" method="post" action="/somewhere">
  ...
  <%= raw Hcaptcha.Template.display %>
  ...
</form>

For invisible hcaptcha

<form name="someform" method="post" action="/somewhere">
  ...
  <%= raw Hcaptcha.Template.display(size: "invisible") %>
</form>
  ...

Since hcaptcha loads Javascript code asynchronously, you cannot immediately submit the captcha form. If you have logic that needs to know if the captcha code has already been loaded (for example disabling submit button until fully loaded), it is possible to pass in a JS-callback that will be called once the captcha has finished loading. This can be done as follows:

<form name="someform" method="post" action="/somewhere">
  ...
  <%= raw Hcaptcha.Template.display(onload: "myOnLoadCallback") %>
</form>
  ...

And then in your JS code:

function myOnLoadCallback() {
  // perform extra actions here
}

display method accepts additional options as a keyword list, the options are:

Option Action Default
noscript Renders default noscript code provided by google false
public_key Sets key to the data-sitekey hCaptcha div attribute Public key from the config file
hl Sets the language of the hCaptcha en

Verify API

Hcaptcha provides the verify/2 method. Below is an example using a Phoenix controller action:

  def create(conn, params) do
    case Hcaptcha.verify(params["h-captcha-response"]) do
      {:ok, response} -> do_something
      {:error, errors} -> handle_error
    end
  end

verify method sends a POST request to the hCAPTCHA API and returns 2 possible values:

{:ok, %Hcaptcha.Response{challenge_ts: timestamp, hostname: host}} -> The captcha is valid, see the documentation for more details.

{:error, errors} -> errors contains atomised versions of the errors returned by the API, See the error documentation for more details. Errors caused by timeouts in HTTPoison or Jason encoding are also returned as atoms. If the hcaptcha request succeeds but the challenge is failed, a :challenge_failed error is returned.

verify method also accepts a keyword list as the third parameter with the following options:

Option Action Default
timeout Time to wait before timeout 5000 (ms)
secret Private key to send as a parameter of the API request Private key from the config file
remote_ip Optional. The user's IP address, used by hCaptcha no default

Testing

In order to test your endpoints you should set the secret key to the following value in order to receive a positive result from all queries to the Hcaptcha engine.

config :hcaptcha,
  secret: "6LeIxAcTAAAAAGG-vFI1TnRWxMZNFuojJ4WifJWe"

Setting up tests without network access can be done also. When configured as such a positive or negative result can be generated locally.

config :hcaptcha,
  http_client: Hcaptcha.Http.MockClient,
  secret: "6LeIxAcTAAAAAGG-vFI1TnRWxMZNFuojJ4WifJWe"


  {:ok, _details} = Hcaptcha.verify("valid_response")

  {:error, _details} = Hcaptcha.verify("invalid_response")

Contributing

Check out CONTRIBUTING.md if you want to help.

License

MIT License.

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A simple hCaptcha library for Elixir applications.

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