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pycrate/pycrate_mobile/TS29281_GTPU.py

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# -*- coding: UTF-8 -*-
#/**
# * Software Name : pycrate
# * Version : 0.5
# *
# * Copyright 2019. Benoit Michau. P1Sec.
# *
# * This library is free software; you can redistribute it and/or
# * modify it under the terms of the GNU Lesser General Public
# * License as published by the Free Software Foundation; either
# * version 2.1 of the License, or (at your option) any later version.
# *
# * This library is distributed in the hope that it will be useful,
# * but WITHOUT ANY WARRANTY; without even the implied warranty of
# * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# * Lesser General Public License for more details.
# *
# * You should have received a copy of the GNU Lesser General Public
# * License along with this library; if not, write to the Free Software
# * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# * MA 02110-1301 USA
# *
# *--------------------------------------------------------
# * File Name : pycrate_mobile/TS29281_GTPU.py
# * Created : 2019-07-08
# * Authors : Benoit Michau
# *--------------------------------------------------------
#*/
__all__ = [
# GTPU Messages
'GTPUEchoRequest',
'GTPUEchoResponse',
'GTPUErrorInd',
'GTPUSuppExtHdrNotif',
'GTPUEndMarker',
'GTPUTunnelStatus',
'GPDU',
# GTPU Message parser and associated errors
'GTPUDispatcher',
'parse_GTPU',
'ERR_GTPU_BUF_TOO_SHORT',
'ERR_GTPU_BUF_INVALID',
'ERR_GTPU_TYPE_NONEXIST'
]
#------------------------------------------------------------------------------#
# 3GPP TS 29.281: General Packet Radio System (GPRS) Tunnelling Protocol
# User Plane (GTPv1-U)
# release 16 (h10)
#------------------------------------------------------------------------------#
from enum import IntEnum
from pycrate_core.utils import *
from pycrate_core.elt import *
from pycrate_core.base import *
from pycrate_mobile.TS29060_GTP import (
# extension header
BufAligned,
GTPHdrExtCont,
GTPHdrExt,
# header
GTPHdrExtList,
GTPHdrOpt,
ProtType_dict,
GTPHdr
)
from pycrate_mobile.TS38415_PDUSess import *
#------------------------------------------------------------------------------#
# GTP-U Extension Header
# TS 29.281, section 5.2
#------------------------------------------------------------------------------#
GTPUNextExtHeader_dict = {
0 : 'No more extension headers',
1 : 'Reserved - Control Plane only',
2 : 'Reserved - Control Plane only',
3 : 'Long PDCP PDU Number',
32 : 'Service Class Indicator',
64 : 'UDP source port of the triggering message',
129 : 'RAN Container',
130 : 'Long PDCP PDU Number',
131 : 'Xw RAN Container',
132 : 'NR RAN Container',
133 : 'PDU Session Container',
192 : 'PDCP PDU Number',
193 : 'Reserved - Control Plane only',
194 : 'Reserved - Control Plane only'
}
class _LongPDCPPDUNumber(GTPHdrExtCont):
_GEN = (
Uint('spare', bl=6, rep=REPR_HEX),
Uint('Value', bl=18),
Uint24('spare', rep=REPR_HEX),
)
# All defined Ext Header
GTPUHdrExtCont_dict = {
3 : _LongPDCPPDUNumber('LongPDCPPDUNumber',
ID=3),
32 : GTPHdrExtCont('ServiceClassInd', GEN=(
Uint8('Value'),
Uint8('spare', rep=REPR_HEX),
), ID=32),
64 : GTPHdrExtCont('UDPPort', GEN=(
Uint16('Value'),
), ID=64),
129 : GTPHdrExtCont('RANContainer',
ID=129),
130 : _LongPDCPPDUNumber('LongPDCPPDUNumber',
ID=130),
131 : GTPHdrExtCont('XwRANContainer',
ID=131),
132 : GTPHdrExtCont('NRRANContainer',
ID=132),
133 : GTPHdrExtCont('PDUSessionContainer', GEN=PDUSessInfo._GEN,
ID=133),
192 : GTPHdrExtCont('PDCPPDUNumber', GEN=(
Uint('Value', bl=15),
Uint('spare', bl=1, rep=REPR_HEX),
), ID=192)
}
# define a dedicated class for GTPU
class GTPUHdrExt(GTPHdrExt):
_ExtCont = GTPUHdrExtCont_dict
# patch the next extension field dict
GTPUHdrExt._GEN[2]._dic = GTPUNextExtHeader_dict
#------------------------------------------------------------------------------#
# GTP-U header
# TS 29.281, section 5.1
#------------------------------------------------------------------------------#
# define a dedicated class for GTPU
class GTPUHdrExtList(GTPHdrExtList):
_GEN = GTPUHdrExt()
class GTPUType(IntEnum):
EchoReq = 1
EchoResp = 2
ErrorInd = 26
SupportedExtensionHeadersNotif = 31
TunnelStatus = 253
EndMarker = 254
GPDU = 255
GTPUType_dict = {e.value: str(e) for e in GTPUType}
class GTPUHdr(GTPHdr):
_GEN = (
Uint('Version', val=1, bl=3), # 1 for GTP 29.060
Uint('PT', val=1, bl=1, dic=ProtType_dict), # 1 for GTP 29.060
Uint('spare', bl=1),
Uint('E', bl=1),
Uint('S', bl=1),
Uint('PN', bl=1),
Uint8('Type', val=GTPUType.EchoReq.value, dic=GTPUType_dict),
Uint16('Len'),
Uint32('TEID', rep=REPR_HEX),
GTPHdrOpt('GTPUHdrOpt'), # optional
GTPUHdrExtList() # optional
)
def __init__(self, *args, **kwargs):
Envelope.__init__(self, *args, **kwargs)
self['Len'].set_valauto(lambda: self._get_len())
self['GTPUHdrOpt'].set_transauto(lambda: False if (self[3]() or self[4]() or self[5]()) else True)
self['GTPUHdrExtList'].set_transauto(lambda: False if self[3]() else True)
#------------------------------------------------------------------------------#
# Information Element Types
# TS 29.281, section 8.1
#------------------------------------------------------------------------------#
class GTPUIE(Envelope):
pass
#------------------------------------------------------------------------------#
# Recovery
# TS 29.281, section 8.2
#------------------------------------------------------------------------------#
class GTPUIERecovery(GTPUIE):
_GEN = (
Uint8('Type', val=14),
Uint8('RestartCounter')
)
#------------------------------------------------------------------------------#
# Tunnel Endpoint Identifier Data I
# TS 29.281, section 8.3
#------------------------------------------------------------------------------#
class GTPUIETEID(GTPUIE):
_GEN = (
Uint8('Type', val=16),
Uint32('TEID', rep=REPR_HEX),
)
#------------------------------------------------------------------------------#
# GTP-U Peer Address
# TS 29.281, section 8.4
#------------------------------------------------------------------------------#
class GTPUIEPeerAddr(GTPUIE):
_GEN = (
Uint8('Type', val=133),
Uint16('Len', dic={4: 'IPv4', 16: 'IPv6'}),
Buf('IP', rep=REPR_HEX),
)
def __init__(self, *args, **kwargs):
GTPUIE.__init__(self, *args, **kwargs)
self[1].set_valauto(lambda: self[2].get_len())
self[2].set_blauto(lambda: self[1].get_val()<<3)
#------------------------------------------------------------------------------#
# Extension Header Type List
# TS 29.281, section 8.5
#------------------------------------------------------------------------------#
class GTPUIEExtHdrList(GTPUIE):
_GEN = (
Uint8('Type', val=141),
Uint8('Num'),
Array('SupportedExtHdr', GEN=Uint8('ExtHdrType'))
)
def __init__(self, *args, **kwargs):
GTPUIE.__init__(self, *args, **kwargs)
self[1].set_valauto(lambda: self[2].get_num())
self[2].set_numauto(lambda: self[1].get_val())
#------------------------------------------------------------------------------#
# Private extension
# TS 29.281, section 8.6
#------------------------------------------------------------------------------#
class GTPUIEPrivateExt(GTPUIE):
_GEN = (
Uint8('Type', val=255),
Uint16('Len'),
Uint16('ExtId'),
Buf('ExtVal', rep=REPR_HEX)
)
def __init__(self, *args, **kwargs):
GTPUIE.__init__(self, *args, **kwargs)
# WARNING: specification does not say how the length prefix is computed
self[1].set_valauto(lambda: 2 + self[3].get_len())
self[3].set_blauto(lambda: max(0, self[1].get_val()-2)<<3)
#------------------------------------------------------------------------------#
# GTP-U Messages
# TS 29.281, section 7
#------------------------------------------------------------------------------#
class _GTPUMsg(Envelope):
ENV_SEL_TRANS = False
def __init__(self, *args, **kwargs):
Envelope.__init__(self, *args, **kwargs)
if 'val' in kwargs:
# in case some values target optional IE, make them non transparent
for vid in kwargs['val'].keys():
elt = self[vid]
if elt and elt.get_trans():
elt.set_trans(False)
def _from_char(self, char):
if self.get_trans():
return
self.__init__()
# decode header
self[0]._from_char(char)
# decode IE(s)
for ie in self._content[1:]:
if not ie.get_trans():
# mandatory IE
ie._from_char(char)
elif char.len_bit() >= 16:
# optional IE
ie.set_trans(False)
ie._from_char(char)
#------------------------------------------------------------------------------#
# Echo Request
# TS 29.281, section 7.2.1
#------------------------------------------------------------------------------#
class GTPUEchoRequest(_GTPUMsg):
_GEN = (
GTPUHdr(val={'Type': GTPUType.EchoReq.value}),
GTPUIEPrivateExt(hier=1, trans=True) # optional
)
#------------------------------------------------------------------------------#
# Echo Response
# TS 29.281, section 7.2.2
#------------------------------------------------------------------------------#
class GTPUEchoResponse(_GTPUMsg):
_GEN = (
GTPUHdr(val={'Type': GTPUType.EchoResp.value}),
GTPUIERecovery(hier=1),
GTPUIEPrivateExt(hier=1, trans=True) # optional
)
#------------------------------------------------------------------------------#
# Supported Extension Headers Notification
# TS 29.281, section 7.2.3
#------------------------------------------------------------------------------#
class GTPUSuppExtHdrNotif(_GTPUMsg):
_GEN = (
GTPUHdr(val={'Type': GTPUType.SupportedExtensionHeadersNotif.value}),
GTPUIEExtHdrList(hier=1)
)
#------------------------------------------------------------------------------#
# Error Indication
# TS 29.281, section 7.3.1
#------------------------------------------------------------------------------#
class GTPUErrorInd(_GTPUMsg):
_GEN = (
GTPUHdr(val={'Type': GTPUType.ErrorInd.value}),
GTPUIETEID(hier=1),
GTPUIEPeerAddr(hier=1),
GTPUIEPrivateExt(hier=1, trans=True) # optional
)
#------------------------------------------------------------------------------#
# End Marker
# TS 29.281, section 7.3.2
#------------------------------------------------------------------------------#
class GTPUEndMarker(_GTPUMsg):
_GEN = (
GTPUHdr(val={'Type': GTPUType.EndMarker.value}),
GTPUIEPrivateExt(hier=1, trans=True) # optional
)
#------------------------------------------------------------------------------#
# Tunnel Status
# TS 29.281, section 7.3.3
#------------------------------------------------------------------------------#
class GTPUTunnelStatus(_GTPUMsg):
_GEN = (
GTPUHdr(val={'Type': GTPUType.TunnelStatus.value}),
GTPUIEPrivateExt(hier=1, trans=True) # optional
)
#------------------------------------------------------------------------------#
# General
# TS 29.281, section 7.1
#------------------------------------------------------------------------------#
class GPDU(Envelope):
_GEN = (
GTPUHdr(val={'Type': GTPUType.GPDU.value}),
Buf('TPDU', hier=1, rep=REPR_HEX)
)
GTPUDispatcher = {
1 : GTPUEchoRequest,
2 : GTPUEchoResponse,
26 : GTPUErrorInd,
31 : GTPUSuppExtHdrNotif,
253 : GTPUTunnelStatus,
254 : GTPUEndMarker,
255 : GPDU,
}
ERR_GTPU_BUF_TOO_SHORT = 1
ERR_GTPU_BUF_INVALID = 2
ERR_GTPU_TYPE_NONEXIST = 3
def parse_GTPU(buf):
"""parses the buffer `buf' for GTP-U message and returns a 2-tuple:
- GTP-U message structure, or None if parsing failed
- parsing error code, 0 if parsing succeeded, > 0 otherwise
"""
if len(buf) < 8:
return None, ERR_GTPU_BUF_TOO_SHORT
if python_version < 3:
type = ord(buf[1])
else:
type = buf[1]
try:
Msg = GTPUDispatcher[type]()
except KeyError:
return None, ERR_GTPU_TYPE_NONEXIST
try:
Msg.from_bytes(buf)
except Exception:
return None, ERR_GTPU_BUF_INVALID
else:
return Msg, 0
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