82 lines
2.8 KiB
Python
82 lines
2.8 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 = Common Address Redundancy Protocol (CARP)
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# scapy.contrib.status = loads
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import struct
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import hmac
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import hashlib
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from scapy.packet import Packet, split_layers, bind_layers
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from scapy.layers.inet import IP
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from scapy.fields import BitField, ByteField, XShortField, XIntField
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from scapy.layers.vrrp import IPPROTO_VRRP, VRRP, VRRPv3
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from scapy.utils import checksum, inet_aton
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from scapy.error import warning
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class CARP(Packet):
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name = "CARP"
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fields_desc = [BitField("version", 4, 4),
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BitField("type", 4, 4),
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ByteField("vhid", 1),
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ByteField("advskew", 0),
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ByteField("authlen", 0),
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ByteField("demotion", 0),
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ByteField("advbase", 0),
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XShortField("chksum", None),
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XIntField("counter1", 0),
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XIntField("counter2", 0),
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XIntField("hmac1", 0),
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XIntField("hmac2", 0),
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XIntField("hmac3", 0),
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XIntField("hmac4", 0),
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XIntField("hmac5", 0)
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]
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def post_build(self, pkt, pay):
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if self.chksum is None:
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pkt = pkt[:6] + struct.pack("!H", checksum(pkt)) + pkt[8:]
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return pkt
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def build_hmac_sha1(self, pw=b'\x00' * 20, ip4l=[], ip6l=[]):
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h = hmac.new(pw, digestmod=hashlib.sha1)
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# XXX: this is a dirty hack. it needs to pack version and type into a single 8bit field # noqa: E501
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h.update(b'\x21')
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# XXX: mac addy if different from special link layer. comes before vhid
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h.update(struct.pack('!B', self.vhid))
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sl = []
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for i in ip4l:
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# sort ips from smallest to largest
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sl.append(inet_aton(i))
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sl.sort()
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for i in sl:
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h.update(i)
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# XXX: do ip6l sorting
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return h.digest()
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warning("CARP overwrites VRRP !")
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# This cancel the bindings done in vrrp.py
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split_layers(IP, VRRP, proto=IPPROTO_VRRP)
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split_layers(IP, VRRPv3, proto=IPPROTO_VRRP)
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# CARP bindings
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bind_layers(IP, CARP, proto=112, dst='224.0.0.18')
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