mastodon/app/controllers/auth/sessions_controller.rb

# frozen_string_literal: true

class Auth::SessionsController < Devise::SessionsController
  include Redisable

  MAX_2FA_ATTEMPTS_PER_HOUR = 10

  layout 'auth'

  skip_before_action :check_self_destruct!
  skip_before_action :require_no_authentication, only: [:create]
  skip_before_action :require_functional!
  skip_before_action :update_user_sign_in

  prepend_before_action :check_suspicious!, only: [:create]

  include Auth::TwoFactorAuthenticationConcern

  content_security_policy only: :new do |p|
    p.form_action(false)
  end

  def check_suspicious!
    user = find_user
    @login_is_suspicious = suspicious_sign_in?(user) unless user.nil?
  end

  def create
    super do |resource|
      # We only need to call this if this hasn't already been
      # called from one of the two-factor or sign-in token
      # authentication methods

      on_authentication_success(resource, :password) unless @on_authentication_success_called
    end
  end

  def destroy
    tmp_stored_location = stored_location_for(:user)
    super
    session.delete(:challenge_passed_at)
    flash.delete(:notice)
    store_location_for(:user, tmp_stored_location) if continue_after?
  end

  def webauthn_options
    user = User.find_by(id: session[:attempt_user_id])

    if user&.webauthn_enabled?
      options_for_get = WebAuthn::Credential.options_for_get(
        allow: user.webauthn_credentials.pluck(:external_id),
        user_verification: 'discouraged'
      )

      session[:webauthn_challenge] = options_for_get.challenge

      render json: options_for_get, status: 200
    else
      render json: { error: t('webauthn_credentials.not_enabled') }, status: 401
    end
  end

  protected

  def find_user
    if user_params[:email].present?
      find_user_from_params
    elsif session[:attempt_user_id]
      User.find_by(id: session[:attempt_user_id])
    end
  end

  def find_user_from_params
    user   = User.authenticate_with_ldap(user_params) if Devise.ldap_authentication
    user ||= User.authenticate_with_pam(user_params) if Devise.pam_authentication
    user ||= User.find_for_authentication(email: user_params[:email])
    user
  end

  def user_params
    params.require(:user).permit(:email, :password, :otp_attempt, credential: {})
  end

  def after_sign_in_path_for(resource)
    last_url = stored_location_for(:user)

    if home_paths(resource).include?(last_url)
      root_path
    else
      last_url || root_path
    end
  end

  def require_no_authentication
    super

    # Delete flash message that isn't entirely useful and may be confusing in
    # most cases because /web doesn't display/clear flash messages.
    flash.delete(:alert) if flash[:alert] == I18n.t('devise.failure.already_authenticated')
  end

  private

  def home_paths(resource)
    paths = [about_path, '/explore']

    paths << short_account_path(username: resource.account) if single_user_mode? && resource.is_a?(User)

    paths
  end

  def continue_after?
    truthy_param?(:continue)
  end

  def restart_session
    clear_attempt_from_session
    redirect_to new_user_session_path, alert: I18n.t('devise.failure.timeout')
  end

  def register_attempt_in_session(user)
    session[:attempt_user_id]         = user.id
    session[:attempt_user_updated_at] = user.updated_at.to_s
  end

  def clear_attempt_from_session
    session.delete(:attempt_user_id)
    session.delete(:attempt_user_updated_at)
  end

  def clear_2fa_attempt_from_user(user)
    redis.del(second_factor_attempts_key(user))
  end

  def check_second_factor_rate_limits(user)
    attempts, = redis.multi do |multi|
      multi.incr(second_factor_attempts_key(user))
      multi.expire(second_factor_attempts_key(user), 1.hour)
    end

    attempts >= MAX_2FA_ATTEMPTS_PER_HOUR
  end

  def on_authentication_success(user, security_measure)
    @on_authentication_success_called = true

    clear_2fa_attempt_from_user(user)
    clear_attempt_from_session

    user.update_sign_in!(new_sign_in: true)
    sign_in(user)
    flash.delete(:notice)

    LoginActivity.create(
      user: user,
      success: true,
      authentication_method: security_measure,
      ip: request.remote_ip,
      user_agent: request.user_agent
    )

    UserMailer.suspicious_sign_in(user, request.remote_ip, request.user_agent, Time.now.utc).deliver_later! if @login_is_suspicious
  end

  def suspicious_sign_in?(user)
    SuspiciousSignInDetector.new(user).suspicious?(request)
  end

  def on_authentication_failure(user, security_measure, failure_reason)
    LoginActivity.create(
      user: user,
      success: false,
      authentication_method: security_measure,
      failure_reason: failure_reason,
      ip: request.remote_ip,
      user_agent: request.user_agent
    )

    # Only send a notification email every hour at most
    return if redis.get("2fa_failure_notification:#{user.id}").present?

    redis.set("2fa_failure_notification:#{user.id}", '1', ex: 1.hour)

    UserMailer.failed_2fa(user, request.remote_ip, request.user_agent, Time.now.utc).deliver_later!
  end

  def second_factor_attempts_key(user)
    "2fa_auth_attempts:#{user.id}:#{Time.now.utc.hour}"
  end

  def respond_to_on_destroy
    respond_to do |format|
      format.json do
        render json: {
          redirect_to: after_sign_out_path_for(resource_name),
        }, status: 200
      end
      format.all { super }
    end
  end
end