Snap.Snaplet.ReCaptcha

This is a snaplet for google's ReCaptcha verification api. This library uses `http-conduit` and keeps connections alive (a maximum of 10). This is an important point in order to avoid denial of service attacks.

See Example and the docs provided here for example usage.

Snaplet and Initialization

data ReCaptcha

Instances

HasReCaptcha ReCaptcha

Typeable * ReCaptcha

class HasReCaptcha b where

Methods

captchaLens :: SnapletLens (Snaplet b) ReCaptcha

Instances

HasReCaptcha ReCaptcha

initReCaptcha :: Maybe (Snaplet (Heist b)) -> SnapletInit b ReCaptcha

Initialise the ReCaptcha snaplet. You are required to have "site_key" and "secret_key" set in the snaplet's configuration file. See 'initReCaptcha\'' if you don't want to use Snap's snaplet configuration mechanism.

This provides optional Heist support, which is implemented using recaptchaScript and recaptchaDiv.

initReCaptcha' :: Maybe (Snaplet (Heist b)) -> (SiteKey, PrivateKey) -> SnapletInit b ReCaptcha

Same as initReCaptcha, but passing the site key and private key explicitly - no configuration on the filesystem is required.

Handlers

checkCaptcha :: HasReCaptcha b => Handler b c ()

pass if the cstate failed. Logs errors (not incorrect captchas) with logError.

 checkCaptcha <|> writeText "Captcha failed!"

See getCaptcha

withCaptcha

Arguments

:: HasReCaptcha b

=> Handler b c ()

Ran on failure

-> Handler b c ()

Ran on success

-> Handler b c ()

Run one of two handlers on either failing or succeeding a captcha.

withCaptcha banForever $ do
  postId <- getParam "id"
  thing  <- getPostParam thing
  addCommentToDB postId thing

See getCaptcha

getCaptcha :: HasReCaptcha b => Handler b c Captcha

Get the ReCaptcha result by querying Google's API.

This requires a "g-recaptcha-response" (POST) parameter to be set in the current request.

See ReCaptchaResult for possible failure types.

cstate <- getCaptcha
case cstate of
  Success               -> writeText "Congratulations! You won."
  Failure               -> writeText "Incorrect cstate answer."
  MissingResponseParam  -> writeText "No g-recaptcha-response in POST"
  InvalidServerResponse -> writeText "Did Google change their API?"
  Errors errs           -> writeText ("Errors: " <> pack (show errs))

This may throw a HttpException if there is a connection-related error.

Types

data Captcha

Constructors

Success

Failure

Errors [Text]

Errors returned by the Captcha. See https://developers.google.com/recaptcha/docs/verify for possible error codes. Note that Failure is used for the case that the only error code returned is "invalid-input-response".

InvalidServerResponse

The server didn't respond with the JSON object required as per https://developers.google.com/recaptcha/docs/verify

MissingResponseParam

There was no "recaptcha_response_field" parameter set in the user request.

Instances

Show Captcha

ToJSON Captcha

FromJSON Captcha

Typeable * Captcha

type PrivateKey = ByteString

type SiteKey = ByteString

Extra

cstate :: Lens' ReCaptcha Captcha

recaptchaScript :: Builder

src='https://www.google.com/recaptcha/api.js' async defer/script

recaptchaDiv :: ByteString -> Builder

For use in a HTML form.