105 lines
3.7 KiB
Python
105 lines
3.7 KiB
Python
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# This file is part of Scapy
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# See http://www.secdev.org/projects/scapy for more information
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# Copyright (C) Philippe Biondi <phil@secdev.org>
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# Copyright (C) 6WIND <olivier.matz@6wind.com>
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# This program is published under a GPLv2 license
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"""
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VRRP (Virtual Router Redundancy Protocol).
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"""
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from scapy.packet import Packet, bind_layers
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from scapy.fields import BitField, ByteField, FieldLenField, FieldListField, \
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IPField, IP6Field, IntField, MultipleTypeField, StrField, XShortField
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from scapy.compat import chb, orb
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from scapy.layers.inet import IP, in4_chksum, checksum
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from scapy.layers.inet6 import IPv6, in6_chksum
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from scapy.error import warning
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IPPROTO_VRRP = 112
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# RFC 3768 - Virtual Router Redundancy Protocol (VRRP)
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class VRRP(Packet):
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fields_desc = [
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BitField("version", 2, 4),
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BitField("type", 1, 4),
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ByteField("vrid", 1),
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ByteField("priority", 100),
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FieldLenField("ipcount", None, count_of="addrlist", fmt="B"),
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ByteField("authtype", 0),
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ByteField("adv", 1),
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XShortField("chksum", None),
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FieldListField("addrlist", [], IPField("", "0.0.0.0"),
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count_from=lambda pkt: pkt.ipcount),
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IntField("auth1", 0),
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IntField("auth2", 0)]
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def post_build(self, p, pay):
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if self.chksum is None:
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ck = checksum(p)
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p = p[:6] + chb(ck >> 8) + chb(ck & 0xff) + p[8:]
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return p
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@classmethod
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def dispatch_hook(cls, _pkt=None, *args, **kargs):
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if _pkt and len(_pkt) >= 9:
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ver_n_type = orb(_pkt[0])
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if ver_n_type >= 48 and ver_n_type <= 57: # Version == 3
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return VRRPv3
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return VRRP
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# RFC 5798 - Virtual Router Redundancy Protocol (VRRP) Version 3
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class VRRPv3(Packet):
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fields_desc = [
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BitField("version", 3, 4),
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BitField("type", 1, 4),
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ByteField("vrid", 1),
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ByteField("priority", 100),
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FieldLenField("ipcount", None, count_of="addrlist", fmt="B"),
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BitField("res", 0, 4),
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BitField("adv", 100, 12),
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XShortField("chksum", None),
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MultipleTypeField(
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[
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(FieldListField("addrlist", [], IPField("", "0.0.0.0"),
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count_from=lambda pkt: pkt.ipcount),
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lambda p: isinstance(p.underlayer, IP)),
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(FieldListField("addrlist", [], IP6Field("", "::"),
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count_from=lambda pkt: pkt.ipcount),
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lambda p: isinstance(p.underlayer, IPv6)),
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],
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StrField("addrlist", "")
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)
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]
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def post_build(self, p, pay):
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if self.chksum is None:
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if isinstance(self.underlayer, IP):
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ck = in4_chksum(112, self.underlayer, p)
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elif isinstance(self.underlayer, IPv6):
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ck = in6_chksum(112, self.underlayer, p)
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else:
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warning("No IP(v6) layer to compute checksum on VRRP. Leaving null") # noqa: E501
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ck = 0
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p = p[:6] + chb(ck >> 8) + chb(ck & 0xff) + p[8:]
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return p
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@classmethod
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def dispatch_hook(cls, _pkt=None, *args, **kargs):
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if _pkt and len(_pkt) >= 16:
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ver_n_type = orb(_pkt[0])
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if ver_n_type < 48 or ver_n_type > 57: # Version != 3
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return VRRP
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return VRRPv3
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# IPv6 is supported only on VRRPv3
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# Warning: those layers need to be un-binded in the CARP contrib module.
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# If you add/remove any, remember to also edit the one in CARP.py
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bind_layers(IP, VRRP, proto=IPPROTO_VRRP)
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bind_layers(IP, VRRPv3, proto=IPPROTO_VRRP)
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bind_layers(IPv6, VRRPv3, nh=IPPROTO_VRRP)
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