1
module Rex::Proto::Gss::Asn1
2
  #
3
  # GSS has some "pseudo-asn1" to wrap up tokens. This function parses that wrapping, extracts
4
  # the mechanism specified, and returns it and the token following it
5
  def unwrap_pseudo_asn1(token)
6
    start_of_token = nil
7
    mech_id = nil
8
    # This bit is pseudo-ASN1 - we parse up until the OID, then take note of where we got up 
9
    # to, and continue parsing from there.
10
    OpenSSL::ASN1.traverse(token) do | depth, offset, header_len, length, constructed, tag_class, tag|
11
      component = token[offset, header_len+length]
12
      if depth == 1 && tag_class == :UNIVERSAL && tag == 6
13
        mech_id = OpenSSL::ASN1.decode(component)
14
        start_of_token = offset+header_len+length
15
        break
16
      end
17
    end
18

19
    [mech_id, token[start_of_token, token.length - start_of_token]]
20
  end
21

22
  def wrap_pseudo_asn1(mech_id, token)
23
    OpenSSL::ASN1::ASN1Data.new(
24
      [
25
        mech_id,
26
        token
27
      ],
28
      0,
29
      :APPLICATION
30
    ).to_der
31
  end
32
end
33

34