Add hCaptcha support (#25019)

app/controllers/auth/confirmations_controller.rb

@@ -1,21 +1,63 @@
 # frozen_string_literal: true
 
 class Auth::ConfirmationsController < Devise::ConfirmationsController
+  include CaptchaConcern
+
   layout 'auth'
 
   before_action :set_body_classes
+  before_action :set_confirmation_user!, only: [:show, :confirm_captcha]
   before_action :require_unconfirmed!
 
+  before_action :extend_csp_for_captcha!, only: [:show, :confirm_captcha]
+  before_action :require_captcha_if_needed!, only: [:show]
+
   skip_before_action :require_functional!
 
+  def show
+    old_session_values = session.to_hash
+    reset_session
+    session.update old_session_values.except('session_id')
+
+    super
+  end
+
   def new
     super
 
     resource.email = current_user.unconfirmed_email || current_user.email if user_signed_in?
   end
 
+  def confirm_captcha
+    check_captcha! do |message|
+      flash.now[:alert] = message
+      render :captcha
+      return
+    end
+
+    show
+  end
+
   private
 
+  def require_captcha_if_needed!
+    render :captcha if captcha_required?
+  end
+
+  def set_confirmation_user!
+    # We need to reimplement looking up the user because
+    # Devise::ConfirmationsController#show looks up and confirms in one
+    # step.
+    confirmation_token = params[:confirmation_token]
+    return if confirmation_token.nil?
+
+    @confirmation_user = User.find_first_by_auth_conditions(confirmation_token: confirmation_token)
+  end
+
+  def captcha_user_bypass?
+    return true if @confirmation_user.nil? || @confirmation_user.confirmed?
+  end
+
   def require_unconfirmed!
     if user_signed_in? && current_user.confirmed? && current_user.unconfirmed_email.blank?
       redirect_to(current_user.approved? ? root_path : edit_user_registration_path)

app/controllers/concerns/captcha_concern.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+module CaptchaConcern
+  extend ActiveSupport::Concern
+  include Hcaptcha::Adapters::ViewMethods
+
+  included do
+    helper_method :render_captcha
+  end
+
+  def captcha_available?
+    ENV['HCAPTCHA_SECRET_KEY'].present? && ENV['HCAPTCHA_SITE_KEY'].present?
+  end
+
+  def captcha_enabled?
+    captcha_available? && Setting.captcha_enabled
+  end
+
+  def captcha_user_bypass?
+    false
+  end
+
+  def captcha_required?
+    captcha_enabled? && !captcha_user_bypass?
+  end
+
+  def check_captcha!
+    return true unless captcha_required?
+
+    if verify_hcaptcha
+      true
+    else
+      if block_given?
+        message = flash[:hcaptcha_error]
+        flash.delete(:hcaptcha_error)
+        yield message
+      end
+      false
+    end
+  end
+
+  def extend_csp_for_captcha!
+    policy = request.content_security_policy
+    return unless captcha_required? && policy.present?
+
+    %w(script_src frame_src style_src connect_src).each do |directive|
+      values = policy.send(directive)
+      values << 'https://hcaptcha.com' unless values.include?('https://hcaptcha.com') || values.include?('https:')
+      values << 'https://*.hcaptcha.com' unless values.include?('https://*.hcaptcha.com') || values.include?('https:')
+      policy.send(directive, *values)
+    end
+  end
+
+  def render_captcha
+    return unless captcha_required?
+
+    hcaptcha_tags
+  end
+end

app/helpers/admin/settings_helper.rb

@@ -1,4 +1,7 @@
 # frozen_string_literal: true
 
 module Admin::SettingsHelper
+  def captcha_available?
+    ENV['HCAPTCHA_SECRET_KEY'].present? && ENV['HCAPTCHA_SITE_KEY'].present?
+  end
 end

app/javascript/styles/mastodon/forms.scss

@@ -136,6 +136,10 @@ code {
     line-height: 22px;
     color: $secondary-text-color;
     margin-bottom: 30px;
+
+    a {
+      color: $highlight-text-color;
+    }
   }
 
   .rules-list {
@@ -1039,6 +1043,10 @@ code {
   }
 }
 
+.simple_form .h-captcha {
+  text-align: center;
+}
+
 .permissions-list {
   &__item {
     padding: 15px;

app/models/form/admin_settings.rb

@@ -33,6 +33,7 @@ class Form::AdminSettings
     content_cache_retention_period
     backups_retention_period
     status_page_url
+    captcha_enabled
   ).freeze
 
   INTEGER_KEYS = %i(
@@ -52,6 +53,7 @@ class Form::AdminSettings
     trendable_by_default
     noindex
     require_invite_text
+    captcha_enabled
   ).freeze
 
   UPLOAD_KEYS = %i(

app/views/admin/settings/registrations/show.html.haml

@@ -20,6 +20,10 @@
     .fields-row__column.fields-row__column-6.fields-group
       = f.input :require_invite_text, as: :boolean, wrapper: :with_label, disabled: !approved_registrations?
 
+  - if captcha_available?
+    .fields-group
+      = f.input :captcha_enabled, as: :boolean, wrapper: :with_label, label: t('admin.settings.captcha_enabled.title'), hint: t('admin.settings.captcha_enabled.desc_html')
+
   .fields-group
     = f.input :closed_registrations_message, as: :text, wrapper: :with_block_label, input_html: { rows: 2 }
 

app/views/auth/confirmations/captcha.html.haml

@@ -0,0 +1,15 @@
+- content_for :page_title do
+  = t('auth.captcha_confirmation.title')
+
+= form_tag auth_captcha_confirmation_url, method: 'POST', class: 'simple_form' do
+  = render 'auth/shared/progress', stage: 'confirm'
+
+  = hidden_field_tag :confirmation_token, params[:confirmation_token]
+
+  %p.lead= t('auth.captcha_confirmation.hint_html')
+
+  .field-group
+    = render_captcha
+
+  .actions
+    %button.button= t('challenge.confirm')