require 'brakeman/checks/base_check'

class Brakeman::CheckNumberToCurrency < Brakeman::BaseCheck
  Brakeman::Checks.add self

  @description = "Checks for number helpers XSS vulnerabilities in certain versions"

  def run_check
    if version_between? "2.0.0", "2.3.18" or
      version_between? "3.0.0", "3.2.16" or
      version_between? "4.0.0", "4.0.2"

      return if lts_version? "2.3.18.8"

      check_number_helper_usage
      generic_warning unless @found_any
    end
  end

  def generic_warning
    message = "Rails #{rails_version} has a vulnerability in number helpers (CVE-2014-0081). Upgrade to Rails version "

    if version_between? "2.3.0", "3.2.16"
      message << "3.2.17"
    else
      message << "4.0.3"
    end

    warn :warning_type => "Cross Site Scripting",
      :warning_code => :CVE_2014_0081,
      :message => message,
      :confidence => CONFIDENCE[:med],
      :gem_info => gemfile_or_environment,
      :link_path => "https://groups.google.com/d/msg/ruby-security-ann/9WiRn2nhfq0/2K2KRB4LwCMJ"
  end

  def check_number_helper_usage
    number_methods = [:number_to_currency, :number_to_percentage, :number_to_human] 
    tracker.find_call(:target => false, :methods => number_methods).each do |result|
      arg = result[:call].second_arg
      next unless arg

      if not check_helper_option(result, arg) and hash? arg
        hash_iterate(arg) do |key, value|
          break if check_helper_option(result, value)
        end
      end
    end
  end

  def check_helper_option result, exp
    if match = (has_immediate_user_input? exp or has_immediate_model? exp)
      match = match.match if match.is_a? Match
      warn_on_number_helper result, match
      @found_any = true
    else
      false
    end
  end

  def warn_on_number_helper result, match
    warn :result => result,
      :warning_type => "Cross Site Scripting",
      :warning_code => :CVE_2014_0081_call,
      :message => "Format options in #{result[:call].method} are not safe in Rails #{rails_version}",
      :confidence => CONFIDENCE[:high],
      :link_path => "https://groups.google.com/d/msg/ruby-security-ann/9WiRn2nhfq0/2K2KRB4LwCMJ",
      :user_input => match
  end
end