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# Copyright (C) 2013, Red Hat, Inc.
# All rights reserved.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
from pyasn1 import error
from pyasn1.codec.der import decoder, encoder
from pyasn1.type import char, namedtype, tag, univ
from kdcproxy.exceptions import ASN1ParsingError, ParsingError
class ProxyMessageKerberosMessage(univ.OctetString):
tagSet = univ.OctetString.tagSet.tagExplicitly(
tag.Tag(tag.tagClassContext, tag.tagFormatConstructed, 0)
)
class ProxyMessageTargetDomain(char.GeneralString):
tagSet = char.GeneralString.tagSet.tagExplicitly(
tag.Tag(tag.tagClassContext, tag.tagFormatConstructed, 1)
)
class ProxyMessageDCLocateHint(univ.Integer):
tagSet = univ.Integer.tagSet.tagExplicitly(
tag.Tag(tag.tagClassContext, tag.tagFormatSimple, 2)
)
class ProxyMessage(univ.Sequence):
pretty_name = 'KDC-PROXY-MESSAGE'
componentType = namedtype.NamedTypes(
namedtype.NamedType('message', ProxyMessageKerberosMessage()),
namedtype.OptionalNamedType('realm', ProxyMessageTargetDomain()),
namedtype.OptionalNamedType('flags', ProxyMessageDCLocateHint())
)
class ASREQ(univ.Sequence):
pretty_name = 'AS-REQ'
tagSet = univ.Sequence.tagSet.tagExplicitly(
tag.Tag(tag.tagClassApplication, tag.tagFormatSimple, 10)
)
class TGSREQ(univ.Sequence):
pretty_name = 'TGS-REQ'
tagSet = univ.Sequence.tagSet.tagExplicitly(
tag.Tag(tag.tagClassApplication, tag.tagFormatSimple, 12)
)
class APREQ(univ.Sequence):
pretty_name = 'AP-REQ'
tagSet = univ.Sequence.tagSet.tagExplicitly(
tag.Tag(tag.tagClassApplication, tag.tagFormatSimple, 14)
)
class KRBPriv(univ.Sequence):
pretty_name = 'KRBPRiv'
tagSet = univ.Sequence.tagSet.tagExplicitly(
tag.Tag(tag.tagClassApplication, tag.tagFormatSimple, 21)
)
def decode_proxymessage(data):
try:
req, tail = decoder.decode(data, asn1Spec=ProxyMessage())
except error.PyAsn1Error as e:
raise ASN1ParsingError(e)
if tail:
raise ParsingError("Invalid request.")
message = req.getComponentByName('message').asOctets()
realm = req.getComponentByName('realm')
if realm.hasValue():
try: # Python 3.x
realm = str(realm, "utf-8")
except TypeError: # Python 2.x
realm = str(realm)
else:
realm = None
flags = req.getComponentByName('flags')
flags = int(flags) if flags.hasValue() else None
return message, realm, flags
def encode_proxymessage(data):
rep = ProxyMessage()
rep.setComponentByName('message', data)
return encoder.encode(rep)
def try_decode(data, cls):
try:
req, tail = decoder.decode(data, asn1Spec=cls())
except error.PyAsn1Error as e:
raise ASN1ParsingError(e)
if tail:
raise ParsingError("%s request has %d extra bytes." %
(cls.pretty_name, len(tail)))
return cls.pretty_name
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