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# -*- coding: binary -*-
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module Rex::Proto::Kerberos::Model
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  # This class provides a representation of a Kerberos ticket that helps
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  # a client authenticate to a service.
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  class TransitedEncoding < Element
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    # @return [Integer] [0] Int32 -- must be registered --
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    attr_accessor :tr_type
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    # @return [String] [1] OCTET STRING
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    attr_accessor :contents
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    # Decodes the Rex::Proto::Kerberos::Model::TransitedEncoding from an input
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    #
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    # @param input [String, OpenSSL::ASN1::ASN1Data] the input to decode from
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    # @return [self] if decoding succeeds
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    # @raise [Rex::Proto::Kerberos::Model::Error::KerberosDecodingError] if decoding doesn't succeed
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    def decode(input)
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      case input
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      when String
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        decode_string(input)
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      when OpenSSL::ASN1::ASN1Data
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        decode_asn1(input)
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      else
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        raise ::Rex::Proto::Kerberos::Model::Error::KerberosDecodingError, 'Failed to decode TransitedEncoding, invalid input'
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      end
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      self
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    end
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    # Encodes a Rex::Proto::Kerberos::Model::TransitedEncoding into an ASN.1 String
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    #
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    # @return [String]
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    def encode
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      to_asn1.to_der
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    end
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    # Encodes a Rex::Proto::Kerberos::Model::TransitedEncoding into ASN.1
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    #
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    # @return [OpenSSL::ASN1::ASN1Data] The TransitedEncoding ASN1Data
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    def to_asn1
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      elems = []
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      elems << OpenSSL::ASN1::ASN1Data.new([encode_tr_type], 0, :CONTEXT_SPECIFIC)
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      elems << OpenSSL::ASN1::ASN1Data.new([encode_contents], 1, :CONTEXT_SPECIFIC)
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      OpenSSL::ASN1::Sequence.new(elems)
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    end
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    private
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    # Decodes a Rex::Proto::Kerberos::Model::TicketEncPart from an String
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    #
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    # @param input [String] the input to decode from
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    def decode_string(input)
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      asn1 = OpenSSL::ASN1.decode(input)
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      decode_asn1(asn1)
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    end
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    # Decodes a Rex::Proto::Kerberos::Model::TransitedEncoding
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    #
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    # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
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    # @raise [Rex::Proto::Kerberos::Model::Error::KerberosDecodingError] if decoding doesn't succeed
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    #
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    #    TransitedEncoding       ::= SEQUENCE {
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    #            tr-type         [0] Int32 -- must be registered --,
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    #            contents        [1] OCTET STRING
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    #    }
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    def decode_asn1(input)
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      input.value.each do |val|
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        case val.tag
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        when 0  # tr-type         [0] Int32 -- must be registered --,
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          self.tr_type = decode_tr_type(val)
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        when 1  # contents        [1] OCTET STRING
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          self.contents = decode_contents(val)
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        else
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          raise ::Rex::Proto::Kerberos::Model::Error::KerberosDecodingError, 'Failed to decode TransitedEncoding SEQUENCE'
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        end
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      end
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    end
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    # Decodes the type from an OpenSSL::ASN1::ASN1Data
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    #
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    # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
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    # @return [Integer]
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    def decode_tr_type(input)
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      input.value[0].value.to_i
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    end
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    # Encodes the type
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    #
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    # @return [OpenSSL::ASN1::Integer]
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    def encode_tr_type
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      bn = OpenSSL::BN.new(tr_type.to_s)
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      OpenSSL::ASN1::Integer.new(bn)
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    end
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    # Decodes the address from an OpenSSL::ASN1::ASN1Data
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    #
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    # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
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    # @return [String]
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    def decode_contents(input)
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      input.value[0].value
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    end
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    # Encodes the contents
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    #
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    # @return [OpenSSL::ASN1::OctetString]
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    def encode_contents
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      OpenSSL::ASN1::OctetString.new(contents)
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    end
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  end
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end
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