373 lines
14 KiB
Python
373 lines
14 KiB
Python
# Copyright (c) 2003-2016 CORE Security Technologies
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#
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# This software is provided under under a slightly modified version
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# of the Apache Software License. See the accompanying LICENSE file
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# for more information.
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#
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# Author: Alberto Solino (beto@coresecurity.com)
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#
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# Description:
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# SPNEGO functions used by SMB, SMB2/3 and DCERPC
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#
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from struct import pack, unpack, calcsize
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############### GSS Stuff ################
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GSS_API_SPNEGO_UUID = '\x2b\x06\x01\x05\x05\x02'
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ASN1_SEQUENCE = 0x30
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ASN1_AID = 0x60
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ASN1_OID = 0x06
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ASN1_OCTET_STRING = 0x04
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ASN1_MECH_TYPE = 0xa0
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ASN1_MECH_TOKEN = 0xa2
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ASN1_SUPPORTED_MECH = 0xa1
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ASN1_RESPONSE_TOKEN = 0xa2
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ASN1_ENUMERATED = 0x0a
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MechTypes = {
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'+\x06\x01\x04\x01\x827\x02\x02\x1e': 'SNMPv2-SMI::enterprises.311.2.2.30',
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'+\x06\x01\x04\x01\x827\x02\x02\n': 'NTLMSSP - Microsoft NTLM Security Support Provider',
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'*\x86H\x82\xf7\x12\x01\x02\x02': 'MS KRB5 - Microsoft Kerberos 5',
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'*\x86H\x86\xf7\x12\x01\x02\x02': 'KRB5 - Kerberos 5',
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'*\x86H\x86\xf7\x12\x01\x02\x02\x03': 'KRB5 - Kerberos 5 - User to User'
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}
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TypesMech = dict((v,k) for k, v in MechTypes.iteritems())
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def asn1encode(data = ''):
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#res = asn1.SEQUENCE(str).encode()
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#import binascii
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#print '\nalex asn1encode str: %s\n' % binascii.hexlify(str)
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if 0 <= len(data) <= 0x7F:
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res = pack('B', len(data)) + data
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elif 0x80 <= len(data) <= 0xFF:
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res = pack('BB', 0x81, len(data)) + data
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elif 0x100 <= len(data) <= 0xFFFF:
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res = pack('!BH', 0x82, len(data)) + data
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elif 0x10000 <= len(data) <= 0xffffff:
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res = pack('!BBH', 0x83, len(data) >> 16, len(data) & 0xFFFF) + data
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elif 0x1000000 <= len(data) <= 0xffffffff:
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res = pack('!BL', 0x84, len(data)) + data
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else:
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raise Exception('Error in asn1encode')
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return str(res)
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def asn1decode(data = ''):
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len1 = unpack('B', data[:1])[0]
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data = data[1:]
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if len1 == 0x81:
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pad = calcsize('B')
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len2 = unpack('B',data[:pad])[0]
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data = data[pad:]
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ans = data[:len2]
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elif len1 == 0x82:
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pad = calcsize('H')
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len2 = unpack('!H', data[:pad])[0]
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data = data[pad:]
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ans = data[:len2]
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elif len1 == 0x83:
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pad = calcsize('B') + calcsize('!H')
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len2, len3 = unpack('!BH', data[:pad])
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data = data[pad:]
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ans = data[:len2 << 16 + len3]
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elif len1 == 0x84:
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pad = calcsize('!L')
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len2 = unpack('!L', data[:pad])[0]
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data = data[pad:]
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ans = data[:len2]
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# 1 byte length, string <= 0x7F
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else:
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pad = 0
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ans = data[:len1]
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return ans, len(ans)+pad+1
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class GSSAPI:
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# Generic GSSAPI Header Format
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def __init__(self, data = None):
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self.fields = {}
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self['UUID'] = GSS_API_SPNEGO_UUID
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if data:
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self.fromString(data)
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pass
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def __setitem__(self,key,value):
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self.fields[key] = value
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def __getitem__(self, key):
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return self.fields[key]
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def __delitem__(self, key):
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del self.fields[key]
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def __len__(self):
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return len(self.getData())
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def __str__(self):
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return len(self.getData())
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def fromString(self, data = None):
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# Manual parse of the GSSAPI Header Format
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# It should be something like
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# AID = 0x60 TAG, BER Length
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# OID = 0x06 TAG
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# GSSAPI OID
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# UUID data (BER Encoded)
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# Payload
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next_byte = unpack('B',data[:1])[0]
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if next_byte != ASN1_AID:
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raise Exception('Unknown AID=%x' % next_byte)
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data = data[1:]
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decode_data, total_bytes = asn1decode(data)
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# Now we should have a OID tag
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next_byte = unpack('B',decode_data[:1])[0]
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if next_byte != ASN1_OID:
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raise Exception('OID tag not found %x' % next_byte)
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decode_data = decode_data[1:]
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# Now the OID contents, should be SPNEGO UUID
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uuid, total_bytes = asn1decode(decode_data)
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self['OID'] = uuid
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# the rest should be the data
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self['Payload'] = decode_data[total_bytes:]
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#pass
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def dump(self):
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for i in self.fields.keys():
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print "%s: {%r}" % (i,self[i])
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def getData(self):
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ans = pack('B',ASN1_AID)
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ans += asn1encode(
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pack('B',ASN1_OID) +
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asn1encode(self['UUID']) +
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self['Payload'] )
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return ans
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class SPNEGO_NegTokenResp:
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# http://tools.ietf.org/html/rfc4178#page-9
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# NegTokenResp ::= SEQUENCE {
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# negState [0] ENUMERATED {
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# accept-completed (0),
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# accept-incomplete (1),
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# reject (2),
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# request-mic (3)
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# } OPTIONAL,
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# -- REQUIRED in the first reply from the target
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# supportedMech [1] MechType OPTIONAL,
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# -- present only in the first reply from the target
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# responseToken [2] OCTET STRING OPTIONAL,
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# mechListMIC [3] OCTET STRING OPTIONAL,
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# ...
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# }
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# This structure is not prepended by a GSS generic header!
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SPNEGO_NEG_TOKEN_RESP = 0xa1
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SPNEGO_NEG_TOKEN_TARG = 0xa0
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def __init__(self, data = None):
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self.fields = {}
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if data:
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self.fromString(data)
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pass
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def __setitem__(self,key,value):
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self.fields[key] = value
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def __getitem__(self, key):
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return self.fields[key]
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def __delitem__(self, key):
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del self.fields[key]
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def __len__(self):
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return len(self.getData())
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def __str__(self):
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return len(self.getData())
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def fromString(self, data = 0):
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payload = data
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next_byte = unpack('B', payload[:1])[0]
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if next_byte != SPNEGO_NegTokenResp.SPNEGO_NEG_TOKEN_RESP:
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raise Exception('NegTokenResp not found %x' % next_byte)
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payload = payload[1:]
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decode_data, total_bytes = asn1decode(payload)
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next_byte = unpack('B', decode_data[:1])[0]
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if next_byte != ASN1_SEQUENCE:
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raise Exception('SEQUENCE tag not found %x' % next_byte)
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decode_data = decode_data[1:]
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decode_data, total_bytes = asn1decode(decode_data)
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next_byte = unpack('B',decode_data[:1])[0]
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if next_byte != ASN1_MECH_TYPE:
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# MechType not found, could be an AUTH answer
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if next_byte != ASN1_RESPONSE_TOKEN:
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raise Exception('MechType/ResponseToken tag not found %x' % next_byte)
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else:
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decode_data2 = decode_data[1:]
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decode_data2, total_bytes = asn1decode(decode_data2)
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next_byte = unpack('B', decode_data2[:1])[0]
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if next_byte != ASN1_ENUMERATED:
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raise Exception('Enumerated tag not found %x' % next_byte)
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item, total_bytes2 = asn1decode(decode_data)
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self['NegResult'] = item
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decode_data = decode_data[1:]
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decode_data = decode_data[total_bytes:]
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# Do we have more data?
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if len(decode_data) == 0:
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return
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next_byte = unpack('B', decode_data[:1])[0]
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if next_byte != ASN1_SUPPORTED_MECH:
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if next_byte != ASN1_RESPONSE_TOKEN:
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raise Exception('Supported Mech/ResponseToken tag not found %x' % next_byte)
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else:
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decode_data2 = decode_data[1:]
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decode_data2, total_bytes = asn1decode(decode_data2)
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next_byte = unpack('B', decode_data2[:1])[0]
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if next_byte != ASN1_OID:
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raise Exception('OID tag not found %x' % next_byte)
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decode_data2 = decode_data2[1:]
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item, total_bytes2 = asn1decode(decode_data2)
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self['SupportedMech'] = item
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decode_data = decode_data[1:]
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decode_data = decode_data[total_bytes:]
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next_byte = unpack('B', decode_data[:1])[0]
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if next_byte != ASN1_RESPONSE_TOKEN:
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raise Exception('Response token tag not found %x' % next_byte)
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decode_data = decode_data[1:]
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decode_data, total_bytes = asn1decode(decode_data)
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next_byte = unpack('B', decode_data[:1])[0]
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if next_byte != ASN1_OCTET_STRING:
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raise Exception('Octet string token tag not found %x' % next_byte)
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decode_data = decode_data[1:]
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decode_data, total_bytes = asn1decode(decode_data)
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self['ResponseToken'] = decode_data
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def dump(self):
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for i in self.fields.keys():
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print "%s: {%r}" % (i,self[i])
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def getData(self):
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ans = pack('B',SPNEGO_NegTokenResp.SPNEGO_NEG_TOKEN_RESP)
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if self.fields.has_key('NegResult') and self.fields.has_key('SupportedMech'):
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# Server resp
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ans += asn1encode(
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pack('B', ASN1_SEQUENCE) +
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asn1encode(
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pack('B',SPNEGO_NegTokenResp.SPNEGO_NEG_TOKEN_TARG) +
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asn1encode(
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pack('B',ASN1_ENUMERATED) +
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asn1encode( self['NegResult'] )) +
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pack('B',ASN1_SUPPORTED_MECH) +
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asn1encode(
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pack('B',ASN1_OID) +
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asn1encode(self['SupportedMech'])) +
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pack('B',ASN1_RESPONSE_TOKEN ) +
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asn1encode(
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pack('B', ASN1_OCTET_STRING) + asn1encode(self['ResponseToken']))))
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elif self.fields.has_key('NegResult'):
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# Server resp
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ans += asn1encode(
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pack('B', ASN1_SEQUENCE) +
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asn1encode(
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pack('B', SPNEGO_NegTokenResp.SPNEGO_NEG_TOKEN_TARG) +
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asn1encode(
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pack('B',ASN1_ENUMERATED) +
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asn1encode( self['NegResult'] ))))
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else:
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# Client resp
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ans += asn1encode(
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pack('B', ASN1_SEQUENCE) +
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asn1encode(
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pack('B', ASN1_RESPONSE_TOKEN) +
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asn1encode(
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pack('B', ASN1_OCTET_STRING) + asn1encode(self['ResponseToken']))))
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return ans
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class SPNEGO_NegTokenInit(GSSAPI):
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# http://tools.ietf.org/html/rfc4178#page-8
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# NegTokeInit :: = SEQUENCE {
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# mechTypes [0] MechTypeList,
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# reqFlags [1] ContextFlags OPTIONAL,
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# mechToken [2] OCTET STRING OPTIONAL,
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# mechListMIC [3] OCTET STRING OPTIONAL,
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# }
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SPNEGO_NEG_TOKEN_INIT = 0xa0
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def fromString(self, data = 0):
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GSSAPI.fromString(self, data)
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payload = self['Payload']
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next_byte = unpack('B', payload[:1])[0]
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if next_byte != SPNEGO_NegTokenInit.SPNEGO_NEG_TOKEN_INIT:
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raise Exception('NegTokenInit not found %x' % next_byte)
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payload = payload[1:]
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decode_data, total_bytes = asn1decode(payload)
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# Now we should have a SEQUENCE Tag
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next_byte = unpack('B', decode_data[:1])[0]
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if next_byte != ASN1_SEQUENCE:
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raise Exception('SEQUENCE tag not found %x' % next_byte)
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decode_data = decode_data[1:]
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decode_data, total_bytes2 = asn1decode(decode_data)
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next_byte = unpack('B',decode_data[:1])[0]
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if next_byte != ASN1_MECH_TYPE:
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raise Exception('MechType tag not found %x' % next_byte)
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decode_data = decode_data[1:]
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remaining_data = decode_data
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decode_data, total_bytes3 = asn1decode(decode_data)
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next_byte = unpack('B', decode_data[:1])[0]
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if next_byte != ASN1_SEQUENCE:
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raise Exception('SEQUENCE tag not found %x' % next_byte)
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decode_data = decode_data[1:]
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decode_data, total_bytes4 = asn1decode(decode_data)
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# And finally we should have the MechTypes
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self['MechTypes'] = []
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while decode_data:
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next_byte = unpack('B', decode_data[:1])[0]
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if next_byte != ASN1_OID:
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# Not a valid OID, there must be something else we won't unpack
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break
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decode_data = decode_data[1:]
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item, total_bytes = asn1decode(decode_data)
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self['MechTypes'].append(item)
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decode_data = decode_data[total_bytes:]
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# Do we have MechTokens as well?
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decode_data = remaining_data[total_bytes3:]
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if len(decode_data) > 0:
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next_byte = unpack('B', decode_data[:1])[0]
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if next_byte == ASN1_MECH_TOKEN:
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# We have tokens in here!
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decode_data = decode_data[1:]
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decode_data, total_bytes = asn1decode(decode_data)
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next_byte = unpack('B', decode_data[:1])[0]
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if next_byte == ASN1_OCTET_STRING:
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decode_data = decode_data[1:]
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decode_data, total_bytes = asn1decode(decode_data)
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self['MechToken'] = decode_data
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def getData(self):
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mechTypes = ''
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for i in self['MechTypes']:
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mechTypes += pack('B', ASN1_OID)
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mechTypes += asn1encode(i)
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mechToken = ''
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# Do we have tokens to send?
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if self.fields.has_key('MechToken'):
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mechToken = pack('B', ASN1_MECH_TOKEN) + asn1encode(
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pack('B', ASN1_OCTET_STRING) + asn1encode(
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self['MechToken']))
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ans = pack('B',SPNEGO_NegTokenInit.SPNEGO_NEG_TOKEN_INIT)
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ans += asn1encode(
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pack('B', ASN1_SEQUENCE) +
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asn1encode(
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pack('B', ASN1_MECH_TYPE) +
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asn1encode(
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pack('B', ASN1_SEQUENCE) +
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asn1encode(mechTypes)) + mechToken ))
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self['Payload'] = ans
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return GSSAPI.getData(self)
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