# -*- coding: binary -*-

module Rex
  module Proto
    module Kerberos
      module Model
        # This class provides a representation of a Kerberos KRB-ERROR (response error)
        # message definition.
        class KrbError < Element
          # @!attribute pvno
          #   @return [Integer] The protocol version number
          attr_accessor :pvno
          # @!attribute msg_type
          #   @return [Integer] The type of a protocol message
          attr_accessor :msg_type
          # @!attribute ctime
          #   @return [Time] The current time of the client's host
          attr_accessor :ctime
          # @!attribute cusec
          #   @return [Integer] The microseconds part of the client timestamp
          attr_accessor :cusec
          # @!attribute stime
          #   @return [Time] The current time of the server
          attr_accessor :stime
          # @!attribute susec
          #   @return [Integer] The microseconds part of the server timestamp
          attr_accessor :susec
          # @!attribute error_code
          #   @return [Rex::Proto::Kerberos::Model::Error::ErrorCode] The error request returned by kerberos or the server when a request fails
          attr_accessor :error_code
          # @!attribute crealm
          #   @return [String] The realm part of the client's principal identifier
          attr_accessor :crealm
          # @!attribute cname
          #   @return [Rex::Proto::Kerberos::Model::PrincipalName] The name part of the client's principal identifier
          attr_accessor :cname
          # @!attribute realm
          #   @return [String] The realm part of the server's principal identifier
          attr_accessor :realm
          # @!attribute sname
          #   @return [Rex::Proto::Kerberos::Model::PrincipalName] The name part of the server's identity
          attr_accessor :sname
          # @!attribute etext
          #   @return [String] Additional text to help explain the error code
          attr_accessor :etext
          # @!attribute e_data
          #   @return [String] additional data about the error (ASN.1 encoded data)
          attr_accessor :e_data

          # Decodes the Rex::Proto::Kerberos::Model::KrbError from an input
          #
          # @param input [String, OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [self] if decoding succeeds
          # @raise [Rex::Proto::Kerberos::Model::Error::KerberosDecodingError] if decoding doesn't succeed
          def decode(input)
            case input
            when String
              decode_string(input)
            when OpenSSL::ASN1::ASN1Data
              decode_asn1(input)
            else
              raise ::Rex::Proto::Kerberos::Model::Error::KerberosDecodingError, 'Failed to decode KrbError, invalid input'
            end

            self
          end

          # Rex::Proto::Kerberos::Model::KrbError encoding isn't supported
          #
          # @raise [NotImplementedError]
          def encode
            raise ::NotImplementedError, 'KrbError encoding not supported'
          end

          # Decodes the e_data field as an Array<PreAuthDataEntry>
          #
          # @return [Array<Rex::Proto::Kerberos::Model::PreAuthDataEntry>]
          def e_data_as_pa_data
            pre_auth = []
            decoded = OpenSSL::ASN1.decode(self.e_data)
            decoded.each do |pre_auth_data|
              pre_auth << Rex::Proto::Kerberos::Model::PreAuthDataEntry.decode(pre_auth_data)
            end

            pre_auth
          end

          # Decodes the e_data field as a PreAuthData
          #
          # @return [Rex::Proto::Kerberos::Model::PreAuthData]
          def e_data_as_pa_data_entry
            if self.e_data
              decoded = OpenSSL::ASN1.decode(self.e_data)
              Rex::Proto::Kerberos::Model::PreAuthDataEntry.decode(decoded)
            else
              # This is implementation-defined, so may be different in some cases
              nil
            end
          end

          private

          # Decodes a Rex::Proto::Kerberos::Model::KrbError from an String
          #
          # @param input [String] the input to decode from
          def decode_string(input)
            asn1 = OpenSSL::ASN1.decode(input)

            decode_asn1(asn1)
          end

          # Decodes a Rex::Proto::Kerberos::Model::KrbError
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @raise [Rex::Proto::Kerberos::Model::Error::KerberosDecodingError] if decoding doesn't succeed
          def decode_asn1(input)
            input.value[0].value.each do |val|
              case val.tag
              when 0
                self.pvno = decode_pvno(val)
              when 1
                self.msg_type = decode_msg_type(val)
              when 2
                self.ctime = decode_ctime(val)
              when 3
                self.cusec = decode_cusec(val)
              when 4
                self.stime = decode_stime(val)
              when 5
                self.susec = decode_susec(val)
              when 6
                self.error_code = decode_error_code(val)
              when 7
                self.crealm = decode_crealm(val)
              when 8
                self.cname = decode_cname(val)
              when 9
                self.realm = decode_realm(val)
              when 10
                self.sname = decode_sname(val)
              when 11
                self.etext = decode_etext(val)
              when 12
                self.e_data = decode_e_data(val)
              else
                raise ::Rex::Proto::Kerberos::Model::Error::KerberosDecodingError, "Failed to decode KRB-ERROR SEQUENCE (#{val.tag})"
              end
            end
          end

          # Decodes the pvno from an OpenSSL::ASN1::ASN1Data
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [Integer]
          def decode_pvno(input)
            input.value[0].value.to_i
          end

          # Decodes the msg_type from an OpenSSL::ASN1::ASN1Data
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [Integer]
          def decode_msg_type(input)
            input.value[0].value.to_i
          end

          # Decodes the ctime field
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [Time]
          def decode_ctime(input)
            input.value[0].value
          end

          # Decodes the cusec field
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [Integer]
          def decode_cusec(input)
            input.value[0].value
          end

          # Decodes the stime field
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [Time]
          def decode_stime(input)
            input.value[0].value
          end

          # Decodes the susec field
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [Integer]
          def decode_susec(input)
            input.value[0].value.to_i
          end

          # Decodes the error_code field
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [Rex::Proto::Kerberos::Model::Error::ErrorCode]
          def decode_error_code(input)
            value = input.value[0].value.to_i

            Error::ErrorCodes::ERROR_MAP[value] || Error::ErrorCode.new('UNKNOWN', value, 'Unknown error')
          end

          # Decodes the crealm field
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [String]
          def decode_crealm(input)
            input.value[0].value
          end

          # Decodes the cname field
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [Rex::Proto::Kerberos::Model::PrincipalName]
          def decode_cname(input)
            Rex::Proto::Kerberos::Model::PrincipalName.decode(input.value[0])
          end

          # Decodes the realm field
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [String]
          def decode_realm(input)
            input.value[0].value
          end

          # Decodes the sname field
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [Rex::Proto::Kerberos::Model::PrincipalName]
          def decode_sname(input)
            Rex::Proto::Kerberos::Model::PrincipalName.decode(input.value[0])
          end

          # Decodes the e-text field
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [String]
          def decode_etext(input)
            input.value[0].value
          end

          # Decodes the e_data from an OpenSSL::ASN1::ASN1Data
          #
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
          # @return [String]
          def decode_e_data(input)
            input.value[0].value
          end
        end
      end
    end
  end
end
