97 lines
3 KiB
Python
97 lines
3 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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# 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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# Original PPI author: <jellch@harris.com>
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# scapy.contrib.description = CACE Per-Packet Information (PPI) header
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# scapy.contrib.status = loads
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"""
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CACE Per-Packet Information (PPI) header.
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A method for adding metadata to link-layer packets.
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For example, one can tag an 802.11 packet with GPS co-ordinates of where it
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was captured, and include it in the PCAP file.
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New PPI types should:
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* Make their packet a subclass of ``PPI_Element``
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* Call ``bind_layers(PPI_Hdr, ExamplePPI, pfh_type=0xffff)``
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See ``layers/contrib/ppi_cace.py`` for an example.
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"""
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from scapy.config import conf
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from scapy.data import DLT_PPI, PPI_TYPES
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from scapy.error import warning
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from scapy.packet import Packet
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from scapy.fields import ByteField, FieldLenField, LEIntField, \
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PacketListField, LEShortEnumField, LenField
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class PPI_Hdr(Packet):
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name = 'PPI Header'
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fields_desc = [
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LEShortEnumField('pfh_type', 0, PPI_TYPES),
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LenField('pfh_length', None, fmt='<H'),
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]
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def mysummary(self):
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return self.sprintf('PPI %pfh_type%')
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class PPI_Element(Packet):
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"""Superclass for all PPI types."""
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name = 'PPI Element'
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def extract_padding(self, s):
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return b'', s
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@staticmethod
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def length_from(pkt):
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if not pkt.underlayer:
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warning('Missing under-layer')
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return 0
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return pkt.underlayer.len
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class PPI(Packet):
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name = 'Per-Packet Information header (PPI)'
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fields_desc = [
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ByteField('version', 0),
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ByteField('flags', 0),
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FieldLenField('len', None, length_of='headers', fmt='<H',
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adjust=lambda p, x: x + 8), # length of this packet
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LEIntField('dlt', None),
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PacketListField('headers', [], PPI_Hdr,
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length_from=lambda p: p.len - 8),
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]
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def add_payload(self, payload):
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Packet.add_payload(self, payload)
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# Update the DLT if not set
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if self.getfieldval('dlt') is None and isinstance(payload, Packet):
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self.setfieldval('dlt', conf.l2types.get(payload.__class__))
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def guess_payload_class(self, payload):
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# Pass DLT handling to conf.l2types.
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return conf.l2types.get(
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self.getfieldval('dlt'), Packet.guess_payload_class(self, payload))
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conf.l2types.register(DLT_PPI, PPI)
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