96 lines
3.5 KiB
Python
96 lines
3.5 KiB
Python
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# This file is part of Scapy
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# Scapy is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 2 of the License, or
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# any later version.
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#
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# Scapy is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Scapy. If not, see <http://www.gnu.org/licenses/>.
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# scapy.contrib.description = Network Services Headers (NSH)
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# scapy.contrib.status = loads
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from scapy.all import bind_layers
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from scapy.fields import BitField, ByteField, ByteEnumField, BitEnumField, \
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ShortField, X3BytesField, XIntField, XStrFixedLenField, \
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ConditionalField, PacketListField, BitFieldLenField
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from scapy.layers.inet import Ether, IP
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from scapy.layers.inet6 import IPv6
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from scapy.layers.vxlan import VXLAN
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from scapy.packet import Packet
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from scapy.layers.l2 import GRE
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from scapy.contrib.mpls import MPLS
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#
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# NSH Support
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# https://www.rfc-editor.org/rfc/rfc8300.txt January 2018
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#
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class NSHTLV(Packet):
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"NSH MD-type 2 - Variable Length Context Headers"
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name = "NSHTLV"
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fields_desc = [
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ShortField('class', 0),
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BitField('type', 0, 8),
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BitField('reserved', 0, 1),
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BitField('length', 0, 7),
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PacketListField('metadata', None, XIntField, count_from='length')
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]
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class NSH(Packet):
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"""Network Service Header.
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NSH MD-type 1 if there is no ContextHeaders"""
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name = "NSH"
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fields_desc = [
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BitField('ver', 0, 2),
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BitField('oam', 0, 1),
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BitField('unused1', 0, 1),
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BitField('ttl', 63, 6),
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BitFieldLenField('length', None, 6,
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count_of='vlch',
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adjust=lambda pkt, x: 6 if pkt.mdtype == 1
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else x + 2),
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BitField('unused2', 0, 4),
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BitEnumField('mdtype', 1, 4, {0: 'Reserved MDType',
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1: 'Fixed Length',
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2: 'Variable Length',
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0xF: 'Experimental MDType'}),
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ByteEnumField('nextproto', 3, {1: 'IPv4',
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2: 'IPv6',
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3: 'Ethernet',
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4: 'NSH',
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5: 'MPLS',
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0xFE: 'Experiment 1',
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0xFF: 'Experiment 2'}),
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X3BytesField('spi', 0),
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ByteField('si', 0xFF),
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ConditionalField(XStrFixedLenField("context_header", "", 16),
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lambda pkt: pkt.mdtype == 1),
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ConditionalField(PacketListField("vlch", None, NSHTLV,
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count_from="length"),
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lambda pkt: pkt.mdtype == 2)
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]
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def mysummary(self):
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return self.sprintf("SPI: %spi% - SI: %si%")
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bind_layers(Ether, NSH, {'type': 0x894F}, type=0x894F)
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bind_layers(VXLAN, NSH, {'flags': 0xC, 'nextproto': 4}, nextproto=4)
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bind_layers(GRE, NSH, {'proto': 0x894F}, proto=0x894F)
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bind_layers(NSH, IP, nextproto=1)
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bind_layers(NSH, IPv6, nextproto=2)
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bind_layers(NSH, Ether, nextproto=3)
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bind_layers(NSH, NSH, nextproto=4)
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bind_layers(NSH, MPLS, nextproto=5)
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