unrar / midb

require 'base64'

require 'cgi'

module MIDB

  module API

    # Controller that handles API HMAC authentication.

    # 

    # @note This will probably become a separate project soon.

    class Security

      # Checks if an HTTP header is the authorization one

      #

      # @deprecated It's no longer used but kept for historical reasons.

      # @param header [String] A line of an HTTP header.

      # Parses an authentication header so to get the HMAC digest.

      #

      # @param header [String] A line of an HTTP header (should have been checked

      #                         to be an auth header)

      # @return [String] The HMAC digest as a string.

      def self.parse_auth(header)

        return header.split(" ")[1]

      end

      # Checks if an HMAC digest is properly authenticated.

      # 

      # @param header [String] A line of an HTTP header (see #parse_auth)

      # @param params [String] The data passed via the HTTP request.

      # @param key [String] The private API key.

      #

      # @return [Boolean] Whether the given digest matches the correct one or not.

      def self.check?(header, params, key)

        hmac = HMAC::SHA1.new(key)

        hmac.update(params)

        return self.parse_auth(header) == CGI.escape(Base64.encode64("#{hmac.digest}"))

      end

    end

  end

end